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1
Scherrmann, Alexander, Heini Wernli, and Emmanouil Flaounas. "Origin of low-tropospheric potential vorticity in Mediterranean cyclones." Weather and Climate Dynamics 4, no. 1 (January 25, 2023): 157–73. http://dx.doi.org/10.5194/wcd-4-157-2023.
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Abstract. Mediterranean cyclones are extratropical cyclones, typically of smaller size and weaker intensity than other cyclones that develop over the main open ocean storm tracks. Nevertheless, Mediterranean cyclones can attain high intensities, even comparable to the ones of tropical cyclones, and thus cause large socioeconomic impacts in the densely populated coasts of the region. After cyclogenesis takes place, a large variety of processes are involved in the cyclone’s development, contributing with positive and negative potential vorticity (PV) changes to the lower-tropospheric PV anomalies in the cyclone center. Although the diabatic processes that produce these PV anomalies in Mediterranean cyclones are known, it is still an open question whether they occur locally within the cyclone itself or remotely in the environment (e.g., near high orography) with a subsequent transport of high-PV air into the cyclone center. This study introduces a Lagrangian method to determine the origin of the lower-tropospheric PV anomaly, which is applied climatologically to ERA5 reanalysis and to 12 monthly simulations, performed with the integrated forecasting system (IFS) model. We define and quantify so-called “cyclonic” and “environmental” PV and find that the main part of the lower-tropospheric PV anomaly (60 %) is produced within the cyclone, shortly prior (−12 h) to the cyclones' mature stage. Nevertheless, in 19.5 % of the cyclones the environmental PV production near the mountains surrounding the Mediterranean Basin plays a significant role in forming the low-tropospheric PV anomaly and therefore in determining the intensity of these cyclones. The analysis of PV tendencies from the IFS simulations reveals that the major PV production inside the cyclone is typically due to convection and microphysics, whereas convection and turbulent momentum tendencies cause most of the positive PV changes in the environment.
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Oruba, Ludivine, Guillaume Lapeyre, and Gwendal Rivière. "On the Northward Motion of Midlatitude Cyclones in a Barotropic Meandering Jet." Journal of the Atmospheric Sciences 69, no. 6 (June 1, 2012): 1793–810. http://dx.doi.org/10.1175/jas-d-11-0267.1.
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Abstract The combined effects of the deformation (horizontal stretching and shearing) and nonlinearities on the beta drift of midlatitude cyclones are studied using a barotropic quasigeostrophic model on the beta plane. It is found that, without any background flow, a cyclonic vortex moves more rapidly northward when it is initially strongly stretched along a mostly north–south direction. This meridional stretching is more efficient at forming an anticyclone to the east of the cyclone through Rossby wave radiation. The cyclone–anticyclone couple then forms a nonlinear vortex dipole that propagates mostly northward. The case of a cyclone embedded in uniformly sheared zonal flows is then studied. A cyclone evolving in an anticyclonic shear is stretched more strongly, develops a stronger anticyclone, and moves faster northward than a cyclone embedded in a cyclonic shear, which remains almost isotropic. Similar results are found in the general case of uniformly sheared nonzonal flows. The evolution of cyclones is also investigated in the case of a more realistic meandering jet whose relative vorticity gradient creates an effective beta and whose deformation field is spatially varying. A statistical study reveals a strong correlation among the cyclone’s stretching, the anticyclone strength, and the velocity toward the jet center. These different observations agree with the more idealized cases. Finally, these results provide a rationale for the existence of preferential zones for the jet-crossing phase: that is, the phase when a cyclone crosses a jet from its anticyclonic to its cyclonic side.
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Chaudhuri, Sutapa, and Anindita De Sarkar. "Severity of Tropical Cyclones atypical during El Nino – A Statistical Elucidation." Asian Journal of Water, Environment and Pollution 6, no. 4 (January 2009): 79–85. http://dx.doi.org/10.3233/ajw-2009-6_4_11.
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Tropical cyclones are one of nature's most violent manifestations and potentially the deadliest of all meteorological phenomena. The casualty associated with major cyclones in the Indian sub-continent gives an idea about its enormous destructive capability. The effect of El Nino over Indian Ocean is not fully understood yet. The present study is an attempt to establish a relationship between El Nino and severity of tropical cyclones. The rationale of the present study is to view whether a persistent cyclonic disturbance leads to the development of a tropical cyclone or severe tropical cyclone during an El Nino year. Statistical techniques are adopted to attain the objectives. The results of the study reveal that in the El Nino year cyclonic disturbances may turn to tropical cyclones but turning to its severity is absolutely unusual.
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Binder, Hanin, Maxi Boettcher, Hanna Joos, and Heini Wernli. "The Role of Warm Conveyor Belts for the Intensification of Extratropical Cyclones in Northern Hemisphere Winter." Journal of the Atmospheric Sciences 73, no. 10 (September 21, 2016): 3997–4020. http://dx.doi.org/10.1175/jas-d-15-0302.1.
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Abstract The role of warm conveyor belts (WCBs) and their associated positive low-level potential vorticity (PV) anomalies are investigated for extratropical cyclones in Northern Hemisphere winter, using ERA-Interim and composite techniques. The Spearman correlation coefficient of 0.68 implies a moderate to strong correlation between cyclone intensification and WCB strength. Hereby, cyclone intensification is quantified by the normalized maximum 24-h central sea level pressure deepening and WCB strength by the WCB air mass associated with the cyclone’s 24-h period of strongest deepening. Explosively intensifying cyclones typically have strong WCBs and pronounced WCB-related PV production in the cyclone center; they are associated with a WCB of type W2, which ascends close to the cyclone center. Cyclones with similar WCB strength but weak intensification are either diabatic Rossby waves, which do not interact with an upper-level disturbance, or cyclones where much of the WCB-related PV production occurs far from the cyclone center and thereby does not contribute strongly to cyclone deepening (WCB of type W1, which ascends mainly along the cold front). The category of explosively intensifying cyclones with weak WCBs is inhomogeneous but often characterized by a very low tropopause or latent heating independent of WCBs. These findings reveal that (i) diabatic PV production in WCBs is essential for the intensification of many explosive cyclones, (ii) the importance of WCBs for cyclone development strongly depends on the location of the PV production relative to the cyclone center, and (iii) a minority of explosive cyclones is not associated with WCBs.
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Dacre, H. F., O. Martínez-Alvarado, and C. O. Mbengue. "Linking Atmospheric Rivers and Warm Conveyor Belt Airflows." Journal of Hydrometeorology 20, no. 6 (June 1, 2019): 1183–96. http://dx.doi.org/10.1175/jhm-d-18-0175.1.
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Abstract Extreme precipitation associated with extratropical cyclones can lead to flooding if cyclones track over land. However, the dynamical mechanisms by which moist air is transported into cyclones is poorly understood. In this paper we analyze airflows within a climatology of cyclones in order to understand how cyclones redistribute moisture stored in the atmosphere. This analysis shows that within a cyclone’s warm sector the cyclone-relative airflow is rearwards relative to the cyclone propagation direction. This low-level airflow (termed the feeder airstream) slows down when it reaches the cold front, resulting in moisture flux convergence and the formation of a band of high moisture content. One branch of the feeder airstream turns toward the cyclone center, supplying moisture to the base of the warm conveyor belt where it ascends and precipitation forms. The other branch turns away from the cyclone center exporting moisture from the cyclone. As the cyclone travels, this export results in a filament of high moisture content marking the track of the cyclone (often used to identify atmospheric rivers). We find that both cyclone precipitation and water vapor transport increase when moisture in the feeder airstream increases, thus explaining the link between atmospheric rivers and the precipitation associated with warm conveyor belt ascent. Atmospheric moisture budgets calculated as cyclones pass over fixed domains relative to the cyclone tracks show that continuous evaporation of moisture in the precyclone environment moistens the feeder airstream. Evaporation behind the cold front acts to moisten the atmosphere in the wake of the cyclone passage, potentially preconditioning the environment for subsequent cyclone development.
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Zy Misa Harivelo, Rakotoarimanana, Rakotoarimanana Zy Harifidy, Pandin Moses Glorino Rumambo, and Waloejo Christrijogo Sumartono. "Analysis of tropical cyclones 2000-2020 in Madagascar." Disaster Advances 15, no. 3 (February 25, 2022): 13–20. http://dx.doi.org/10.25303/1503da1320.
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Madagascar is among the ten countries most exposed to cyclonic disasters in the world due to its geographical position. The country faces serious problems directly related to tropical cyclones every year. This research aims to analyze the cyclones in Madagascar from 2000 to 2020 focusing on the impact of the cyclone based on human losses and costs. The findings showed that during the past 20 years, 39 significant cyclones have affected Madagascar. On an average, 02 cyclones per year hit the country but its frequency has been decreasing since 2014. Cyclone Eline, Gafilo and Ivan were considered the most dangerous and have caused serious damages to the country. The number of victims caused by the cyclone, Eline, in 2000 were numerous while the cyclone Ivan in 2008 led many people to homelessness. In addition, the cyclone Gafilo in 2004 was recorded as the deadliest, costliest and has provoked many injuries including missing people. The number of victims, homeless, injured, missing and the cost of damage increase depending on the intensity of the cyclone. The East, North-East, West and Southwest coasts are most often hit by cyclones. Despite the frequency and damage of cyclones in the country, the actions carried out to reduce or mitigate the impacts of cyclones are still not sustainable, which makes the populations more vulnerable.
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Knowland, K. Emma, Ruth M. Doherty, Kevin I. Hodges, and Lesley E. Ott. "The influence of mid-latitude cyclones on European background surface ozone." Atmospheric Chemistry and Physics 17, no. 20 (October 19, 2017): 12421–47. http://dx.doi.org/10.5194/acp-17-12421-2017.
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Abstract. The relationship between springtime mid-latitude cyclones and background ozone (O3) is explored using a combination of observational and reanalysis data sets. First, the relationship between surface O3 observations at two rural monitoring sites on the west coast of Europe – Mace Head, Ireland, and Monte Velho, Portugal – and cyclone track frequency in the surrounding regions is examined. Second, detailed case study examination of four individual mid-latitude cyclones and the influence of the associated frontal passage on surface O3 is performed. Cyclone tracks have a greater influence on the O3 measurements at the more northern coastal European station, Mace Head, located within the main North Atlantic (NA) storm track. In particular, when cyclones track north of 53° N, there is a significant relationship with high levels of surface O3 (> 75th percentile). The further away a cyclone is from the NA storm track, the more likely it will be associated with both high and low (< 25th percentile) levels of O3 at the observation site during the cyclone's life cycle. The results of the four case studies demonstrate (a) the importance of the passage of a cyclone's cold front in relation to surface O3 measurements, (b) the ability of mid-latitude cyclones to bring down high levels of O3 from the stratosphere, and (c) that accompanying surface high-pressure systems and their associated transport pathways play an important role in the temporal variability of surface O3. The main source of high O3 to these two sites in springtime is from the stratosphere, either from direct injection into the cyclone or associated with aged airstreams from decaying downstream cyclones that can become entrained and descend toward the surface within new cyclones over the NA region.
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Rudeva, Irina, and Sergey K. Gulev. "Composite Analysis of North Atlantic Extratropical Cyclones in NCEP–NCAR Reanalysis Data." Monthly Weather Review 139, no. 5 (May 2011): 1419–46. http://dx.doi.org/10.1175/2010mwr3294.1.
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Composite analysis of North Atlantic midlatitudinal winter cyclones is performed using NCEP–NCAR reanalysis data for the 60-yr period from 1948 to 2007. The composites were developed using an advanced methodology involving the coordinate transform of cyclones into a nondimensional azimuthal coordinate system and the further collocation of fields. Composite analysis is performed for air–sea turbulent fluxes, heat content, precipitable water, and precipitation for 576 oceanic cyclones generated in the Gulf Stream area in winter (January–March) from 1948 to 2007. For the region of cyclone generation over the Gulf Stream, composites were analyzed for different cyclone intensities. Over the whole North Atlantic, composites were developed throughout the life cycle and for different cyclone types classified by the regions of their migration. These classifications allow the case-to-case variability to be minimized and the robustness of the composite to be boosted. In the region of cyclone generation over the Gulf Stream, characteristics of the composites strongly depend on the cyclone intensity quantified through the radial sea level pressure difference between the cyclone’s edge and its center. Stronger cyclone intensity implies larger turbulent fluxes in the rear of a cyclone and stronger precipitation in the forward part. Cyclones gradually dry with the water content and precipitation rate decreasing by about 40% and 50%–70%, respectively, during the lifetime. Although composites of air–sea turbulent fluxes show locally very strong positive fluxes in the rear part of the cyclone, the total air–sea turbulent fluxes provided by cyclones are not significantly different from the averaged background fluxes. This shows that the formation of extreme air–sea fluxes by cyclones is connected to the larger-scale circulation conditions, particularly to the cyclone–anticyclone transition zones.
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Sahoo, Umesh Chandra, Suresh Ranjan Dash, and Chandra Sekhar Sahu. "Climate-resilient road design in coastal areas subjected to cyclones and associated floods." Infrastructure Asset Management 8, no. 4 (December 1, 2021): 209–18. http://dx.doi.org/10.1680/jinam.21.00010.
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Cyclones and the associated floods have recently become a regular problem for many states of India, particularly on its west and east coasts. Odisha (renamed from Orissa in 2011) is a state located along the eastern coast of India that experiences tropical cyclones mainly from the Bay of Bengal. Some of the recent severe cyclonic storms that caused large-scale devastation in Odisha in the last decade include cyclone Amphan in May 2020, cyclone Fani in May 2019, cyclone Titli in October 2018, cyclone Hudhud in October 2014 and cyclone Phailin in October 2013. The roads, being one of the essential lifeline infrastructure facilities, commonly get damaged during these cyclonic floods in terms of floodwater overtopping, erosion of road surfaces, shoulders and embankment slopes, and even the washing out of the whole roadway section. These recent events have indicated that special attention is needed to minimise damage to this vital lifeline infrastructure by developing and adopting climate-resilient road infrastructure. This paper focuses on the damage assessment of transportation infrastructure during the recent cyclones and associated floods in Odisha, and advances some recommendations for possible measures to be taken for the design of cyclone- and flood-resilient road infrastructure.
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Lim, Eun-Pa, and Ian Simmonds. "Southern Hemisphere Winter Extratropical Cyclone Characteristics and Vertical Organization Observed with the ERA-40 Data in 1979–2001." Journal of Climate 20, no. 11 (June 1, 2007): 2675–90. http://dx.doi.org/10.1175/jcli4135.1.
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Abstract The mean characteristics and trends of Southern Hemisphere (SH) winter extratropical cyclones occurring at six levels of the troposphere over the period 1979–2001 have been investigated using the 40-yr ECMWF Re-Analysis (ERA-40) data. Cyclonic systems were identified with the Melbourne University cyclone finding and tracking scheme. This study shows that mean sea level pressure (MSLP) cyclones are more numerous, more intense, smaller, deeper, and slower moving than higher-level cyclones. The novel vertical tracing scheme devised for this research revealed that about 52% of SH winter MSLP cyclones have a vertically well organized structure, extending through to the 500-hPa level. About 80% of these vertically coherent SH cyclones keep their westward tilt until the surface cyclones reach their maximum depths, and the mean distance is 300 km between the surface and the 500-hPa level cyclone centers when the surface cyclones obtain their maturity. According to the authors’ definition of vertical organization, explosively developing cyclones are vertically very well organized systems, whose surface development is antecedent to their 500-hPa level counterpart. Over 1979–2001 cyclones have increased in their system density, intensity, and translational velocity but decreased in their scale at almost all levels. However, some of the trends are not statistically significant. The proportion of vertically well organized systems in the entire population of SH winter extratropical cyclones has considerably increased over the last 23 yr, and the mean distance between the surface and the 500-hPa- level cyclone centers has decreased. Such changes in vertical organization of extratropical cyclones are statistically significant at the 95% confidence level.
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Flaounas, Emmanouil, Suzanne L. Gray, and Franziska Teubler. "A process-based anatomy of Mediterranean cyclones: from baroclinic lows to tropical-like systems." Weather and Climate Dynamics 2, no. 1 (March 29, 2021): 255–79. http://dx.doi.org/10.5194/wcd-2-255-2021.
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Abstract. In this study, we address the question of the atmospheric processes that turn Mediterranean cyclones into severe storms. Our approach applies online potential vorticity (PV) budget diagnostics and piecewise PV inversion to WRF model simulations of the mature stage of 100 intense Mediterranean cyclones. We quantify the relative contributions of different processes to cyclone development and therefore deliver, for the first time, a comprehensive insight into the variety of cyclonic systems that develop in the Mediterranean from the perspective of cyclone dynamics. In particular, we show that all 100 cyclones are systematically influenced by two main PV anomalies: a major anomaly in the upper troposphere, related to the baroclinic forcing of cyclone development, and a minor anomaly in the lower troposphere, related to diabatic processes and momentum forcing of wind. Among the diabatic processes, latent heat is shown to act as the main PV source (reinforcing cyclones), being partly balanced by PV sinks of temperature diffusion and radiative cooling (weakening cyclones). Momentum forcing is shown to have an ambiguous feedback, able to reinforce and weaken cyclones while in certain cases playing an important role in cyclone development. Piecewise PV inversion shows that most cyclones develop due to the combined effect of both baroclinic and diabatic forcing, i.e. due to both PV anomalies. However, the stronger the baroclinic forcing, the less a cyclone is found to develop due to diabatic processes. Several pairs of exemplary cases are used to illustrate the variety of contributions of atmospheric processes to the development of Mediterranean cyclones: (i) cases where both baroclinic and diabatic processes contribute to cyclone development; (ii) cases that mainly developed due to latent-heat release; (iii) cases developing in the wake of the Alps; and (iv) two unusual cases, one where momentum forcing dominates cyclone development and the other presenting a dual-surface pressure centre. Finally, we focus on 10 medicane cases (i.e. tropical-like cyclones). In contrast to their tropical counterparts – but in accordance with most intense Mediterranean cyclones – most medicanes are shown to develop under the influence of both baroclinic and diabatic processes. In discussion of medicane-driving processes, we highlight the need for a physical definition of these systems.
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Surinati, Dewi, and Dwi Ayu Kusuma. "KARAKTERISTIK DAN DAMPAK SIKLON TROPIS YANG TUMBUH DI SEKITAR WILAYAH INDONESIA." OSEANA 43, no. 2 (October 30, 2018): 1–12. http://dx.doi.org/10.14203/oseana.2018.vol.43no.2.16.
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CHARACTERISTICS AND IMPACTS OF TROPICAL CYCLONES GROWING AROUND INDONESIAN TERRITORY. Tropical cyclone is a cyclonic originates from tropical oceans and driven principally by heat transfer from the ocean. Tropical cyclone is an atmospheric phenomenon characterized by the emergence of low air pressure that triggers the occurrence of strong winds due to the process of heat transfer from the equator to the latitude. This phenomenon can not be prevented, so that it has great potential to impact on the damage in the area it through. Tropical cyclones can be characterized through their life cycle, scale of power and how it impacts in the area it through. The Cempaka and Dahlia tropical cyclone occuring in 2017 greatly influenced territory of Indonesia. The effect of the cyclone causes extreme weather in Indonesia, especially in areas close to where cyclones are formed.
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DZIUBAK, Tadeusz. "The problems of dust extraction from air intake cyclonic dedusters of special vehicle engines." Combustion Engines 139, no. 4 (November 1, 2009): 34–44. http://dx.doi.org/10.19206/ce-117166.
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An ejective system of dust extraction from a cyclonic deduster has been discussed. The influence of rate of extraction m0 on the characteristics of purification efficiency and flow drag of cyclonic dedusters and individual cyclones has been presented. The values of optimum extraction rate have been given. The authors have analyzed the reasons for lower efficiency of multicyclone extraction versus the extraction of an individual cyclone, from which mutlicyclones are composed. A methodology of experimental research of extraction uniformity from individual cyclones of a multicyclone has been presented. Streams QSC have been measured from individual cyclones of a multicyclone in the air cleaner. The authors have analyzed the performed investigations.
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Wang, Yanchao, Peiyang Li, Zhitao Liang, Huanbo Yang, and Feng Li. "Characterisation of the Overflow Pipe Structure on the Internal Flow Field of a Hydrocyclone." Processes 13, no. 1 (January 16, 2025): 248. https://doi.org/10.3390/pr13010248.
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The application of cyclones can be traced back to 100 years ago. Salt, an important carrier of energy exchange in the human body, is one of the essential substances. Currently, salt surface impurities are mostly removed manually, resulting in low sorting efficiency. Cyclones, as important physical separation equipment, are widely used in separating different substances. This paper focuses on using cyclones for salt decontamination. However, due to the limitations of the cyclone’s structure, ensuring grading accuracy is challenging. The flow field, as the main power source in the cyclone grading process, significantly impacts the grading effect. The overflow pipe, where fine particles exit, has a significant effect on the internal flow field. To explore the impact of the overflow pipe structure on the cyclone’s internal flow field, five overflow pipe structures were designed and numerically analyzed. The results indicate that the improved overflow tube structure has higher static pressure than the conventional linear structure. Type 2 (Parabolic) has the highest tangential velocity, which is 27.7 percentage points higher than that of the conventional cyclone, while Type 3 (hyperbola) has the lowest axial velocity(minimum value is only 0.3 m/s) and turbulence intensity(minimum value of the cone segment is only 0.2), resulting in longer particle residence time in the cyclone for better separation. Additionally, vortices are effectively avoided, improving the stability of the flow field to some extent. The obtained data provide a theoretical basis and support for the structural design of new cyclones.
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Venkat Ratnam, M., S. Ravindra Babu, S. S. Das, G. Basha, B. V. Krishnamurthy, and B. Venkateswararao. "Effect of tropical cyclones on the stratosphere–troposphere exchange observed using satellite observations over the north Indian Ocean." Atmospheric Chemistry and Physics 16, no. 13 (July 15, 2016): 8581–91. http://dx.doi.org/10.5194/acp-16-8581-2016.
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Abstract. Tropical cyclones play an important role in modifying the tropopause structure and dynamics as well as stratosphere–troposphere exchange (STE) processes in the upper troposphere and lower stratosphere (UTLS) region. In the present study, the impact of cyclones that occurred over the north Indian Ocean during 2007–2013 on the STE processes is quantified using satellite observations. Tropopause characteristics during cyclones are obtained from the Global Positioning System (GPS) radio occultation (RO) measurements, and ozone and water vapour concentrations in the UTLS region are obtained from Aura Microwave Limb Sounder (MLS) satellite observations. The effect of cyclones on the tropopause parameters is observed to be more prominent within 500 km of the centre of the tropical cyclone. In our earlier study, we observed a decrease (increase) in the tropopause altitude (temperature) up to 0.6 km (3 K), and the convective outflow level increased up to 2 km. This change leads to a total increase in the tropical tropopause layer (TTL) thickness of 3 km within 500 km of the centre of cyclone. Interestingly, an enhancement in the ozone mixing ratio in the upper troposphere is clearly noticed within 500 km from the cyclone centre, whereas the enhancement in the water vapour in the lower stratosphere is more significant on the south-east side, extending from 500 to 1000 km away from the cyclone centre. The cross-tropopause mass flux for different intensities of cyclones is estimated and it is found that the mean flux from the stratosphere to the troposphere for cyclonic storms is 0.05 ± 0.29 × 10−3 kg m−2, and for very severe cyclonic storms it is 0.5 ± 1.07 × 10−3 kg m−2. More downward flux is noticed on the north-west and south-west side of the cyclone centre. These results indicate that the cyclones have significant impact in effecting the tropopause structure, ozone and water vapour budget, and consequentially the STE in the UTLS region.
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Portal, Alice, Shira Raveh-Rubin, Jennifer L. Catto, Yonatan Givon, and Olivia Martius. "Linking compound weather extremes to Mediterranean cyclones, fronts, and airstreams." Weather and Climate Dynamics 5, no. 3 (August 19, 2024): 1043–60. http://dx.doi.org/10.5194/wcd-5-1043-2024.
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Abstract. Mediterranean cyclones are the primary driver of many types of surface weather extremes in the Mediterranean region, the association with extreme rainfall being the most established. The large-scale characteristics of a Mediterranean cyclone, the properties of the associated airflows and temperature fronts, the interaction with the Mediterranean Sea and with the topography around the basin, and the season of occurrence all contribute to determining its surface impacts. Here, we take these factors into account to interpret the statistical links between Mediterranean cyclones and compound extremes of two types, namely co-occurring rain–wind and wave–wind extremes. Compound extremes are attributed to a cyclone if they fall within a specially defined Mediterranean cyclone impact area. Our results show that the majority of Mediterranean rain–wind and wave–wind extremes occur in the neighbourhood of a Mediterranean cyclone, with local peaks exceeding 80 %. The fraction of compounds happening within a cyclone's impact area is highest when considering transition seasons and for rain–wind events compared with wave–wind events. Winter cyclones, matching with the peak occurrence of large and distinctively baroclinic cyclones, are associated with the highest compound frequency. A novel deconstruction of cyclones' impact areas based on the presence of objectively identified airstreams and fronts reveals a high incidence of both types of compound extremes below warm conveyor belt ascent regions and of wave–wind extremes below regions of dry intrusion outflow.
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Sondermann, Marcely, Sin Chan Chou, Renata Genova Martins, Lucas Costa Amaro, and Rafael de Oliveira Gomes. "Explosive Cyclone Impact on the Power Distribution Grid in Rio Grande do Sul, Brazil." Climate 12, no. 3 (February 24, 2024): 29. http://dx.doi.org/10.3390/cli12030029.
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Southern Brazil is a region strongly influenced by the occurrence of extratropical cyclones. Some of them go through a rapid and intense deepening and are known as explosive cyclones. These cyclones are associated with severe weather conditions such as heavy rainfall, strong winds, and lightning, leading to various natural disasters and causing socioeconomic losses. This study investigated the interaction between atmospheric and oceanic conditions that contributed to the rapid intensification of the cyclone that occurred near the coast of South Brazil from 29 June to 3 July 2020, causing significant havoc. Hourly atmospheric and oceanic data from the ERA5 reanalysis were employed in this analysis. The results showed that warm air and moisture transportation were key contributors to these phenomena. In addition, the interaction between the jet stream and the cyclone’s movement played a crucial role in cyclone formation and intensification. Positive sea surface temperature anomalies also fueled the cyclone’s intensification. These anomalies increased the surface heat fluxes, making the atmosphere more unstable and promoting a strong upward motion. Due to the strong winds and the heavy rainfall, the explosive cyclone caused substantial impacts on the power services, resulting in widespread power outages, damaged infrastructure, and interruptions in energy distribution. This work describes in detail the cyclone development and intensification and aims at the understanding of these storms, which is crucial for minimizing their aftermaths, especially on energy distribution.
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Basheer Ahammed, K. K., Arvind Chandra Pandey, Bikash Ranjan Parida, Wasim, and Chandra Shekhar Dwivedi. "Impact Assessment of Tropical Cyclones Amphan and Nisarga in 2020 in the Northern Indian Ocean." Sustainability 15, no. 5 (February 22, 2023): 3992. http://dx.doi.org/10.3390/su15053992.
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The Northern Indian Ocean (NIO) is one of the most vulnerable coasts to tropical cyclones (TCs) and is frequently threatened by global climate change. In the year 2020, two severe cyclones formed in the NIO and devastated the Indian subcontinent. Super cyclone Amphan, which formed in the Bay of Bengal (BOB) on 15 May 2020, made landfall along the West Bengal coast with a wind speed of above 85 knots (155 km/h). The severe cyclone Nisarga formed in the Arabian Sea (ARS) on 1 June 2020 and made landfall along the Maharashtra coast with a wind speed above 60 knots (115 km/h). The present study has characterized both TCs by employing past cyclonic events (1982–2020), satellite-derived sea surface temperature (SST), wind speed and direction, rainfall dataset, and regional elevation. Long-term cyclonic occurrences revealed that the Bay of Bengal encountered a higher number of cyclones each year than the ARS. Both cyclones had different intensities when making landfall; however, the regional elevation played a significant role in controlling the cyclonic wind and associated hazards. The mountain topography on the east coast weakened the wind, while the deltas on the west coast had no control over the wind. Nisarga weakened to 30 knots (56 km/h) within 6 h from making landfall, while Amphan took 24 h to weaken to 30 knots (56 km/h). We analyzed precipitation patterns during the cyclones and concluded that Amphan had much more (1563 mm) precipitation than Nisarga (684 mm). Furthermore, the impact on land use land cover (LULC) was examined in relation to the wind field. The Amphan wind field damaged 363,837 km2 of land, whereas the Nisarga wind field affected 167,230 km2 of land. This research can aid in the development of effective preparedness strategies for disaster risk reduction during cyclone impacts along the coast of India.
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McCoy, Daniel T., Paul R. Field, Gregory S. Elsaesser, Alejandro Bodas-Salcedo, Brian H. Kahn, Mark D. Zelinka, Chihiro Kodama, et al. "Cloud feedbacks in extratropical cyclones: insight from long-term satellite data and high-resolution global simulations." Atmospheric Chemistry and Physics 19, no. 2 (January 30, 2019): 1147–72. http://dx.doi.org/10.5194/acp-19-1147-2019.
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Abstract. A negative extratropical shortwave cloud feedback driven by changes in cloud optical depth is a feature of global climate models (GCMs). A robust positive trend in observed liquid water path (LWP) over the last two decades across the warming Southern Ocean supports the negative shortwave cloud feedback predicted by GCMs. This feature has been proposed to be due to transitions from ice to liquid with warming. To gain insight into the shortwave cloud feedback we examine extratropical cyclone variability and the response of extratropical cyclones to transient warming in GCM simulations. Multi-Sensor Advanced Climatology Liquid Water Path (MAC-LWP) microwave observations of cyclone properties from the period 1992–2015 are contrasted with GCM simulations, with horizontal resolutions ranging from 7 km to hundreds of kilometers. We find that inter-cyclone variability in LWP in both observations and models is strongly driven by the moisture flux along the cyclone's warm conveyor belt (WCB). Stronger WCB moisture flux enhances the LWP within cyclones. This relationship is replicated in GCMs, although its strength varies substantially across models. It is found that more than 80 % of the enhancement in Southern Hemisphere (SH) extratropical cyclone LWP in GCMs in response to a transient 4 K warming can be predicted based on the relationship between the WCB moisture flux and cyclone LWP in the historical climate and their change in moisture flux between the historical and warmed climates. Further, it is found that that the robust trend in cyclone LWP over the Southern Ocean in observations and GCMs is consistent with changes in the moisture flux. We propose two cloud feedbacks acting within extratropical cyclones: a negative feedback driven by Clausius–Clapeyron increasing water vapor path (WVP), which enhances the amount of water vapor available to be fluxed into the cyclone, and a feedback moderated by changes in the life cycle and vorticity of cyclones under warming, which changes the rate at which existing moisture is imported into the cyclone. Both terms contribute to increasing LWP within the cyclone. While changes in moisture flux predict cyclone LWP trends in the current climate and the majority of changes in LWP in transient warming simulations, a portion of the LWP increase in response to climate change that is unexplained by increasing moisture fluxes may be due to phase transitions. The variability in LWP within cyclone composites is examined to understand what cyclonic regimes the mixed-phase cloud feedback is relevant to. At a fixed WCB moisture flux cyclone LWP increases with increasing sea surface temperature (SST) in the half of the composite poleward of the low and decreases in the half equatorward of the low in both GCMs and observations. Cloud-top phase partitioning observed by the Atmospheric Infrared Sounder (AIRS) indicates that phase transitions may be driving increases in LWP in the poleward half of cyclones.
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Nigro, Melissa A., John J. Cassano, and Shelley L. Knuth. "Evaluation of Antarctic Mesoscale Prediction System (AMPS) cyclone forecasts using infrared satellite imagery." Antarctic Science 24, no. 2 (October 17, 2011): 183–92. http://dx.doi.org/10.1017/s0954102011000745.
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AbstractThe Antarctic coast is an area of high cyclonic activity. Specifically, the regions of Terra Nova Bay, in the western Ross Sea, and Byrd Glacier, in the western Ross Ice Shelf, are prone to cyclone development. The United States, New Zealand, and Italian Antarctic programmes conduct extensive research activities in the region of the western Ross Sea. Due to the harsh weather conditions associated with the cyclonic systems that occur in this region and the abundant research activities in the area, it is important to be able to accurately predict the timing, location and strength of cyclones in this sector of Antarctica. This study evaluates the ability of the Antarctic Mesoscale Prediction System (from 2006–09) to accurately forecast cyclones in the region of the western Ross Sea by comparing the Antarctic Mesoscale Prediction System forecasts to cyclones identified in infrared satellite imagery. The results indicate that the Antarctic Mesoscale Prediction System is able to accurately predict the presence of cyclones about 40% of the time (at a minimum) and the presence of no cyclones about 70% of the time.
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Büeler, Dominik, and Stephan Pfahl. "Potential Vorticity Diagnostics to Quantify Effects of Latent Heating in Extratropical Cyclones. Part I: Methodology." Journal of the Atmospheric Sciences 74, no. 11 (October 27, 2017): 3567–90. http://dx.doi.org/10.1175/jas-d-17-0041.1.
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Abstract Extratropical cyclones develop because of baroclinic instability, but their intensification is often substantially amplified by diabatic processes, most importantly, latent heating (LH) through cloud formation. Although this amplification is well understood for individual cyclones, there is still need for a systematic and quantitative investigation of how LH affects cyclone intensification in different, particularly warmer and moister, climates. For this purpose, the authors introduce a simple diagnostic to quantify the contribution of LH to cyclone intensification within the potential vorticity (PV) framework. The two leading terms in the PV tendency equation, diabatic PV modification and vertical advection, are used to derive a diagnostic equation to explicitly calculate the fraction of a cyclone’s positive lower-tropospheric PV anomaly caused by LH. The strength of this anomaly is strongly coupled to cyclone intensity and the associated impacts in terms of surface weather. To evaluate the performance of the diagnostic, sensitivity simulations of 12 Northern Hemisphere cyclones with artificially modified LH are carried out with a numerical weather prediction model. Based on these simulations, it is demonstrated that the PV diagnostic captures the mean sensitivity of the cyclones’ PV structure to LH as well as parts of the strong case-to-case variability. The simple and versatile PV diagnostic will be the basis for future climatological studies of LH effects on cyclone intensification.
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Ignatyeva, Y. I., and N. I. Tananaev. "Recurrence of cyclonic events over the Sakha Republic (Yakutia) in summer months." Vestnik of North-Eastern Federal University Series "Earth Sciences", no. 2 (June 26, 2024): 46–53. http://dx.doi.org/10.25587/2587-8751-2024-2-46-53.
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Extratropical cyclones over the Sakha Republic (Yakutia) bring rains and reduce the probability of forest fires, but can cause fast rainflood events caused by heavy precipitation. In this study, recurrence of cyclonic events over the Sakha Republic (Yakutia) in summer months between 1950 and 2022 is considered. Recurrence of cyclonic events was defined as the count of cyclone centers over Yakutia or subregions at a standard time of observations. Extratropical cyclone centers database from University of Manitoba (Canada) based on ERA5 reanalysis was used in this study. Cyclonic weather over the territory of the Sakha Republic (Yakutia) persists for 27.5 days on average. The largest count of cyclonic events is noted in the North-Eastern and North-Western sub-regions, while the smallest is in the Southern and Central sub-regions. Across summer months, cyclones are most active in June in all regions except for the Southern sub-region. Here, increased July cyclonic activity is determined by conditions favorable for atmospheric blocking, limited zonal transport promoting the northward intrusion of southern cyclones. There is no pronounced trend in the frequency of occurrence of cyclones except for some regions and months: Western Area, June, increasing; the Sakha Republic (Yakutia), August, decreasing. An absolute minimum in the number of cyclonic events was established for 2019-2021, which, as we believe, was one of the main reasons for the maximum of forest fire activity in the Sakha Republic (Yakutia) observed in these years, along with the Lena River extremely low flows of 2019. An analysis of the circulation conditions leading to such extremes will make it possible to assess the risk of recurrence of similar situations under the future climate.
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Stanković, Aleksa, Gabriele Messori, Joaquim G. Pinto, and Rodrigo Caballero. "Large-scale perspective on extreme near-surface winds in the central North Atlantic." Weather and Climate Dynamics 5, no. 2 (June 14, 2024): 821–37. http://dx.doi.org/10.5194/wcd-5-821-2024.
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Abstract. This study investigates the role of large-scale atmospheric processes in the development of cyclones causing extreme surface winds over the central North Atlantic basin (30 to 60° N, 10 to 50° W), focusing on the extended winter period (October–March) from 1950 until 2020 in the ERA5 reanalysis product. Extreme surface wind events are identified as footprints of spatio-temporally contiguous 10 m wind exceedances over the local 98th percentile. Cyclones that cause the top 1 % most intense wind footprints are identified. After excluding 16 (14 %) of cyclones that originated as tropical cyclones, further analysis is done on the remaining 99 extratropical cyclones (“top extremes”). These are compared to a set of cyclones yielding wind footprints with exceedances marginally above the 98th percentile (“moderate extremes”). Cyclones leading to top extremes are, from their time of cyclogenesis, characterised by the presence of pre-existing downstream cyclones, a strong polar jet, and positive upper-level potential vorticity anomalies to the north. All these features are absent or much weaker in the case of moderate extremes, implying that they play a key role in the explosive development of top extremes and in the generation of spatially extended wind footprints. There is also an indication of cyclonic Rossby wave breaking preceding the top extremes. Furthermore, analysis of the pressure tendency equation over the cyclones' evolution reveals that, although the leading contributions to surface pressure decrease vary from cyclone to cyclone, top extremes have on average a larger diabatic contribution than moderate extremes.
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Zhu, Jiong, and Jian Cheng Kang. "Relationship between Sea Temperature Change and Tropical Cyclones Based on Argo." Advanced Materials Research 250-253 (May 2011): 2782–86. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.2782.
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The relationship between sea water temperature with depth and the maximum cyclone wind speed was analyzed, the temperature was acquired before 24h of the cyclones occurred by using of data of Argo floats and cyclones in 2005, and taking advantage of inverse distance weighted interpolation method. The results showed that: (1) the Tropical Cyclone’s intensity had a strong correlation with the sea water temperature in the depth of about 42m or so. (2) Under the conditions of similar latitude, according to the energy conservation law, the maximum intensity of cyclones wind was a linear function of sea water temperature, depth, and continuous change in the overall rate, which was verified through the actual observation data.
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Gong, Qinglong, Yina Diao, Ruipeng Sun, Xuejun Xiong, and Jilin Sun. "Diagnostic Analysis of the Generative Mechanism of Extratropical Cyclones in the Northwest Pacific and Northwest Atlantic." Atmosphere 12, no. 10 (October 11, 2021): 1326. http://dx.doi.org/10.3390/atmos12101326.
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We investigated the early-stage development of cyclones occurring in the strong baroclinic regions in the Northwest Pacific and the Northwest Atlantic based on European Center for Medium-range Weather Forecasts Re-Analysis-Interim (ERA-Interim) data. The composite background conditions corresponding to the cyclones on the onset day are characterized by upper troposphere divergence of westerly jet ahead of a trough, low troposphere convergence of westerly jet behind a trough, and strong meridional air temperature gradient (baroclinicity) both in the Northwest Pacific and the Northwest Atlantic, but with stronger baroclinicity in the Northwest Pacific. The composite velocity and temperature fields of the cyclone on the onset day show a clear horizontal front and a westward and northward vertical tilting of cyclonic circulation to the cold zone. The composite Northwest Pacific cyclone filed on the onset day has a warm core, whereas the composite Northwest Atlantic cyclone field has a cold core in the low troposphere. The leading adiabatic processes that contribute to the developing of the cold core cyclone in the Northwest Atlantic on the onset day is the temperature advection, while stronger vertical motion induces stronger adiabatic warming in the Northwest Pacific cyclones, which has a significant contribution to the development of warm core cyclones on the onset day.
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Farukh, MA, MAM Hossen, and S. Ahmed. "Impact of extreme cyclone events on coastal agriculture in Bangladesh." Progressive Agriculture 30 (May 29, 2019): 33–41. http://dx.doi.org/10.3329/pa.v30i0.41555.
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Extreme cyclone events are now occurring more frequently in Bangladesh. Bangladesh experiences severe 52 cyclones from 1960 to 2010 where, the approximate percentage of storm surge impact is 40%, the largest in the world. A severe cyclone in 1970 and 1991 caused loss of 300,000 and 200,000 lives. It is reported that 210000, 36000, and 3500 tonnes of boro rice, aus rice, and other food crops (e.g. potatoes and vegetables) were totally destroyed by 1991 cyclone. The storm surge killed huge livestock and caused loss of 100% of freshwater fish. Recently, the super cyclonic storm SIDR (2007) and AILA (2009) affected 10,000 and 300,000 people, respectively. Apart from these, cyclones NARGIS (2008) and MOHASEN (2013) are also mentionable. The crop production in the coastal regions of Bangladesh is most vulnerable by cyclones while, sea level rise by 2050 will inundate 17.7% of southern coastal areas. Tropical cyclones could become more frequent with more strength under recent climate change conditions. In this research, a new dimension of extreme weather assessment is done combining GCM and GIS technology and using tropospheric instability indices. The thermodynamic environment, vertical instability characteristics of severe cyclones are indispensable to cope with climate change conditions, and for planning, disaster management, and to reduce the risk of food insufficiency.
Progressive Agriculture, Vol. 30, Suppl. 1: 33-41, 2019
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Binder, Hanin, Hanna Joos, Michael Sprenger, and Heini Wernli. "Warm conveyor belts in present-day and future climate simulations – Part 2: Role of potential vorticity production for cyclone intensification." Weather and Climate Dynamics 4, no. 1 (January 3, 2023): 19–37. http://dx.doi.org/10.5194/wcd-4-19-2023.
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Abstract. Warm conveyor belts (WCBs) are strongly ascending, cloud- and precipitation-forming airstreams in extratropical cyclones. The intense cloud-diabatic processes produce low-level cyclonic potential vorticity (PV) along the ascending airstreams, which often contribute to the intensification of the associated cyclone. This study investigates how climate change affects the cyclones' WCB strength and the importance of WCB-related diabatic PV production for cyclone intensification, based on present-day (1990–1999) and future (2091–2100) climate simulations of the Community Earth System Model Large Ensemble (CESM-LE). In each period, a large number of cyclones and their associated WCB trajectories have been identified in both hemispheres during the winter season. WCB trajectories are identified as strongly ascending air parcels that rise at least 600 hPa in 48 h. Compared to ERA-Interim reanalyses, the present-day climate simulations are able to capture the cyclone structure and the associated WCBs reasonably well, which gives confidence in future projections with CESM-LE. However, the amplitude of the diabatically produced low-level PV anomaly in the cyclone centre is underestimated in the climate simulations, most likely because of reduced vertical resolution compared to ERA-Interim. The comparison of the simulations for the two climates reveals an increase in the WCB strength and the cyclone intensification rate in the Southern Hemisphere (SH) in the future climate. The WCB strength also increases in the Northern Hemisphere (NH) but to a smaller degree, and the cyclone intensification rate is not projected to change considerably. Hence, in the two hemispheres cyclone intensification responds differently to an increase in WCB strength. Cyclone deepening correlates positively with the intensity of the associated WCB, with a Spearman correlation coefficient of 0.68 (0.66) in the NH in the present-day (future) simulations and a coefficient of 0.51 (0.55) in the SH. The number of explosive cyclones with strong WCBs, referred to as C1 cyclones, is projected to increase in both hemispheres, while the number of explosive cyclones with weak WCBs (C3 cyclones) is projected to decrease. A composite analysis reveals that in the future climate C1 cyclones will be associated with even stronger WCBs, more WCB-related diabatic PV production, the formation of a more intense PV tower, and an increase in precipitation. They will become warmer, moister, and slightly more intense. The findings indicate that (i) latent heating associated with WCBs (as identified with our method) will increase, (ii) WCB-related PV production will be even more important for explosive cyclone intensification than in the present-day climate, and (iii) the interplay between dry and moist dynamics is crucial to understand how climate change affects cyclone intensification.
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Spicer, Chrystopher J. "‘Touching the edges of cyclones’: Thea Astley and the winds of revelation." Queensland Review 25, no. 1 (June 2018): 137–48. http://dx.doi.org/10.1017/qre.2018.12.
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AbstractThea Astley once commented that, ‘everybody is living on a cyclonic edge’, and that many of her characters were ‘always touching on the edges of cyclones’. In Queensland literature, cyclones often appear as tropes of apocalypse: new worlds of person and place are revealed out of the destruction of the old. In Astley's novelA Boat Load of Home Folk(1968), the tempestuous forces of personal cyclones, as well as those of the cyclone destroying the island around them, overtake a group of stranded cruise passengers, and consequently place and person assume unique meanings as the characters try to survive. Although one of her least-known works,A Boat Load of Home Folkis a profound novel of human experience in which Astley uses the elemental cyclone as a trope of apocalypse that is both an instrument of destruction and a catalyst of revelation.
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SINGH, CHARAN, SUNIT DAS, R. B. VERMA, B. L. VERMA, and B. K. BANDYOPADHYAY. "Rainfall estimation of landfalling tropical cyclones over Indian coasts through satellite imagery." MAUSAM 63, no. 2 (December 16, 2021): 193–202. http://dx.doi.org/10.54302/mausam.v63i2.1377.
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One of the most significant impacts of landfalling tropical cyclones is caused by the copiousrainfall associated with it. The main emphasis of present study is to provide some guidance to the operational forecastersfor indicating the possible rainfall over the areas likely to be affected by the cyclones after landfall. Study of 14 pastlandfalling cyclones reveals that the maximum rainfall occurred in the first forward quadrant of tropical cyclonemovement, followed by the second quadrant and the areas near the track of the cyclones. Isohyetal analysis of 24 hoursrainfall for each cyclone reveals that occurrence of heavy rainfall is generally confined up to 150 kms radius from thestorm centre and rainfall is found to generally extend up to 300 kms with gradual decrease in amount. The rainfallreceiving areas are mostly covered with convective clouds with cloud top temperatures of -80 to -60 ºC, prior to and afterthe landfall of the systems. In 93% of tropical cyclones out of the 14 cases studied, 70 % convection lay to the right of thetrack. To examine the rainfall asymmetry due to asymmetry in distribution of convection, cloud top temperatures derivedfrom satellite infrared imagery data have been taken as the proxy of strong convection. It is also revealed in the study thatthe slow moving tropical cyclones cause heavy rain rather than fast moving tropical cyclones. The Bay of Bengalcyclones which crossed coast as cyclonic storm and very severe cyclonic storm caused 71.4% rainfall within the range 0-10 cm, 22.8% rainfall in the range 11-20 cm and 4.3% rainfall within the range 21-30 cm in the area of radius of 300 kmsfrom the centre of the cyclonic storms. For the Arabian Sea tropical cyclones, in general, about 70% rainfall occurredwithin the range 16-25 cm in 24 hours.
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Cavicchia, Leone, Acacia Pepler, Andrew Dowdy, and Kevin Walsh. "A Physically Based Climatology of the Occurrence and Intensification of Australian East Coast Lows." Journal of Climate 32, no. 10 (April 26, 2019): 2823–41. http://dx.doi.org/10.1175/jcli-d-18-0549.1.
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Abstract The subtropical part of the eastern Australian seaboard experiences intense cyclonic activity. The severe damage caused by the intense storms in the region, known as east coast lows (ECLs), has motivated a number of recent studies. Cyclones in this region appear to be driven by a combination of different (barotropic and baroclinic) formation mechanisms, consistent with the view emerging in the last decades that cyclones span a continuous spectrum of dynamical structures, with the barotropically driven tropical cyclone and the baroclinically driven extratropical cyclone being only the extremes of such a spectrum. In this work we revisit the climatology of cyclone occurrence in the subtropical east coast of Australia as seen in a global reanalysis, systematically applying classification criteria based on the cyclone vertical structure and thermal core. Moreover, we investigate the underlying processes driving the cyclone rapid intensification by means of an atmospheric limited-area energetics analysis. We show that ECLs have different spatial patterns according to the cyclone thermal structure, with the fraction of hybrid cyclones being larger toward the tropics and closer to the coast. Moreover, we find that explosively deepening cyclones in this region are driven by a different combination of processes with respect to the global case, with barotropic processes in the surrounding environment having a more dominant role in the energetics of cyclone rapid intensification. The findings of this work contribute to understanding the physical processes underlying the formation and intensification of Australian east coast lows and the associated coastal damage and risk.
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Rashid, Md Bazlar, Md Rubbel Sheikh, A. J. M. Emadul Haque, and Muhammad Abdul Aziz Patwari. "Climate Change Impact and Frequency of Cyclone Surge in Bangladesh Coast: Proper Plan to Address Sustainably." International Journal of Economic and Environmental Geology 13, no. 2 (July 22, 2022): 15–20. https://doi.org/10.46660/ijeeg.vol13.iss2.2022.699.
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The Bay of Bengal (BoB) is a familiar ground for tropical cyclones. Consequently, cyclone surge and tidal inundation are very common in the Bangladesh coast which causes massive loss of human lives and properties. The present paper is an attempt to delineate the frequency of cyclones in the BoB, and loss of human lives and properties of Bangladesh coast on the basis of published reports, open source data and field checking, and finally to propose an effective way out to protect the area from cyclone surge. This study exposes that the frequency of cyclones in the area increased recently due to rise of global temperature. It further reveals that though the frequency of cyclones is increased, the loss of human lives is significantly decreased. Death toll in the last two decades decreased a lot for similar strength of cyclones comparing to the toll in last thirty or fifty years. Improvement in the early warning system, evacuation plan with proper training and construction of good number of cyclone shelter all over the coastal region are the main reason for this improvement. Though the loss of human lives is significantly reduced, the loss of economic resources in the coastal areas of the country is enormous as in earlier episodes. Therefore, adaptation for the Climate Change effect is needed to expedite with afforestation in the coastal region. Economic loss might also be reduced obstructing the cyclonic surge in the coastal region. Considering the cyclone path and tidal amplitude of cyclonic surge, upgradation or reconstruction of the coastal embankments all along the coast is essential. In this process, it is important to ensure that the tidal channels act as an inlet and outlets all over the coast to keep the natural processes active. An integrated approach including geoscientists, engineers, planners, policy makers, etc. is required to protect the resources as well as proper management of the coastal areas of the country.
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Rashida, Md Bazlar, Md Rubel Sheika, A. J. M. Emdadul Haquea, and Mohammad Abdul Aziz Patwarya. "Climate Change Impact and Frequency of Cyclone Surge in Bangladesh Coast: Proper Plan to Address Sustainably." International Journal of Economic and Environmental Geology 13, no. 2 (June 20, 2022): 15–20. http://dx.doi.org/10.46660/ijeeg.v13i2.25.
Full textAbstract:
The Bay of Bengal (BoB) is a familiar ground for tropical cyclones. Consequently, cyclone surge and tidal inundation are very common in the Bangladesh coast which causes massive loss of human lives and properties. The present paper is an attempt to delineate the frequency of cyclones in the BoB, and loss of human lives and properties of Bangladesh coast on the basis of published reports, open source data and field checking, and finally to propose an effective way out to protect the area from cyclone surge. This study exposes that the frequency of cyclones in the area increased recently due to rise of global temperature. It further reveals that though the frequency of cyclones is increased, the loss of human lives is significantly decreased. Death toll in the last two decades decreased a lot for similar strength of cyclones comparing to the toll in last thirty or fifty years. Improvement in the early warning system, evacuation plan with proper training and construction of good number of cyclone shelter all over the coastal region are the main reason for this improvement. Though the loss of human lives is significantly reduced, the loss of economic resources in the coastal areas of the country is enormous as in earlier episodes. Therefore, adaptation for the Climate Change effect is needed to expedite with afforestation in the coastal region. Economic loss might also be reduced obstructing the cyclonic surge in the coastal region. Considering the cyclone path and tidal amplitude of cyclonic surge, upgradation or reconstruction of the coastal embankments all along the coast is essential. In this process, it is important to ensure that the tidal channels act as an inlet and outlets all over the coast to keep the natural processes active. An integrated approach including geoscientists, engineers, planners, policy makers, etc. is required to protect the resources as well as proper management of the coastal areas of the country.
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Swee, Hannah. "Assembling Local Cyclone Knowledge in the Australian Tropics." Nature and Culture 12, no. 1 (March 1, 2017): 8–26. http://dx.doi.org/10.3167/nc.2017.120102.
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In Far North Queensland, a region in the northeast of Australia, cyclones are an annual risk. As a result of this frequency of cyclonic activity, different forms of cyclone knowledge exist ranging from disaster management information to local conceptualizations. For the people that inhabit this region, cyclones are a lived reality that are known in different, seemingly contradictory ways. Drawing on fifteen months of ethnographic fieldwork conducted in Far North Queensland from 2012 to 2015, this article explores how local cyclone knowledge is assembled from a variety of heterogeneous factors that change and fluctuate through time, and are subject to an ongoing process of evaluation.
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Tang, Brian, and Kerry Emanuel. "A Ventilation Index for Tropical Cyclones." Bulletin of the American Meteorological Society 93, no. 12 (December 1, 2012): 1901–12. http://dx.doi.org/10.1175/bams-d-11-00165.1.
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An important environmental control of both tropical cyclone intensity and genesis is vertical wind shear. One hypothesized pathway by which vertical shear affects tropical cyclones is midlevel ventilation—or the flux of low-entropy air into the center of the tropical cyclone. Based on a theoretical framework, a ventilation index is introduced that is equal to the environmental vertical wind shear multiplied by the nondimensional midlevel entropy deficit divided by the potential intensity. The ventilation index has a strong influence on tropical cyclone climatology. Tropical cyclogenesis preferentially occurs when and where the ventilation index is anomalously low. Both the ventilation index and the tropical cyclone's normalized intensity, or the intensity divided by the potential intensity, constrain the distribution of tropical cyclone intensification. The most rapidly intensifying storms are characterized by low ventilation indices and intermediate normalized intensities, while the most rapidly weakening storms are characterized by high ventilation indices and high normalized intensities. Since the ventilation index can be derived from large-scale fields, it can serve as a simple and useful metric for operational forecasts of tropical cyclones and diagnosis of model errors.
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De, Somnath, Shraddha Gupta, Vishnu R. Unni, Rewanth Ravindran, Praveen Kasthuri, Norbert Marwan, Jürgen Kurths, and R. I. Sujith. "Study of interaction and complete merging of binary cyclones using complex networks." Chaos: An Interdisciplinary Journal of Nonlinear Science 33, no. 1 (January 2023): 013129. http://dx.doi.org/10.1063/5.0101714.
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Cyclones are among the most hazardous extreme weather events on Earth. In certain scenarios, two co-rotating cyclones in close proximity to one another can drift closer and completely merge into a single cyclonic system. Identifying the dynamic transitions during such an interaction period of binary cyclones and predicting the complete merger (CM) event are challenging for weather forecasters. In this work, we suggest an innovative approach to understand the evolving vortical interactions between the cyclones during two such CM events (Noru–Kulap and Seroja–Odette) using time-evolving induced velocity-based unweighted directed networks. We find that network-based indicators, namely, in-degree and out-degree, quantify the changes in the interaction between the two cyclones and are excellent candidates to classify the interaction stages before a CM. The network indicators also help to identify the dominant cyclone during the period of interaction and quantify the variation of the strength of the dominating and merged cyclones. Finally, we show that the network measures also provide an early indication of the CM event well before its occurrence.
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Rivière, Gwendal, Jean-Baptiste Gilet, and Ludivine Oruba. "Understanding the Regeneration Stage Undergone by Surface Cyclones Crossing a Midlatitude Jet in a Two-Layer Model." Journal of the Atmospheric Sciences 70, no. 9 (September 1, 2013): 2832–53. http://dx.doi.org/10.1175/jas-d-12-0345.1.
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Abstract The present paper provides a rationale for the regeneration stage undergone by surface cyclones when they cross a baroclinic jet from its anticyclonic-shear (warm) side to its cyclonic-shear (cold) side in a two-layer quasigeostrophic model. To do so, the evolution of finite-amplitude synoptic cyclones in various baroclinic zonal flows is analyzed. Baroclinic zonal flows with uniform horizontal shears are first considered. While the anticyclonic shear allows a much more efficient and sustainable extraction of potential energy than the cyclonic shear, the growth of the lower-layer eddy kinetic energy (EKE) is shown to be highly dependent on the choice of the parameter values. An increased vertical shear leads to a more rapid EKE increase in the anticyclonic shear than in the cyclonic shear whereas increasing the vertically averaged potential vorticity gradient or the barotropic shear stabilizes the EKE more in the former shear than in the latter. Finally, vertical velocities arising from the nonlinear interaction between synoptic cyclones are shown to favor EKE growth in the cyclonic shear rather than in the anticyclonic one. The evolution of cyclones initialized on the warm side of a meridionally confined baroclinic jet is then investigated. The lower-layer cyclone crosses the jet axis and undergoes two distinct growth stages. The first growth stage results from the classical baroclinic interaction and is mainly driven by linear interaction between the cyclones and the jet. The second growth stage is mainly a nonlinear process. It is triggered by the vertical velocities created by the three-dimensional structure of the cyclonic disturbances when they reach the cyclonic side of the jet.
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Aragão, Leonardo, and Federico Porcù. "Cyclonic activity in the Mediterranean region from a high-resolution perspective using ECMWF ERA5 dataset." Climate Dynamics 58, no. 5-6 (October 15, 2021): 1293–310. http://dx.doi.org/10.1007/s00382-021-05963-x.
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AbstractThis study focuses on developing a new Cyclone Detection and Tracking Method (CDTM) to take advantage of the recent availability of a high-resolution reanalysis dataset of ECMWF ERA5. The proposed algorithm is used to perform a climatological analysis of the cyclonic activity in the Mediterranean Region (MR) into a 40-year window (1979–2018). The tuning of the new CDTM was based on the comparison with currently available CDTMs and verified through careful subjective analysis to fully exploit the finer details of MR cyclones features. The application of the new CDTM to the ERA5 high-resolution dataset resulted in an increase of 40% in the annual number of cyclones, mainly associated with subsynoptic and baroclinic driven lows. The main cyclogenetic areas and seasonal cycle were properly identified into the MR context, including areas often underestimated, such as the Aegean Sea, and emerging new ones with cyclogenetic potential such as the coast of Tunisia and Libya. The better cyclone features description defined three distinct periods of cyclonic activity in the MR with peculiar and persistent characteristics. In the first period (Apr–Jun), cyclones develop more frequently and present higher velocities and deepening rates. In the second (Jul–Sep), the cyclonic activity is governed by thermal lows spreading slowly over short tracks without reaching significant depths. In the last and longest season (Oct–Mar), cyclones become less frequent, but with the highest deepening rates and the lowest MSLP values, ranking this period as the most favourable to intense storms.
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Yanase, Wataru, and Hiroshi Niino. "Parameter Sweep Experiments on a Spectrum of Cyclones with Diabatic and Baroclinic Processes." Journal of the Atmospheric Sciences 76, no. 7 (June 18, 2019): 1917–35. http://dx.doi.org/10.1175/jas-d-18-0232.1.
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Abstract A wide range of environments that prevail over the globe generate various types of cyclones such as tropical, extratropical, and hybrid cyclones. In this paper, idealized numerical experiments are used to explore a spectrum of cyclones ranging from the diabatic type to the baroclinic type in a parameter space consisting of three environmental factors: temperature, vertical shear, and planetary vorticity. The experiments reproduce not only typical dynamics of tropical and extratropical cyclones but also their modified dynamics, which are consistent with theoretical studies; tropical cyclones are suppressed by vertical shear, while extratropical cyclones are intensified by condensational heating. The experiments also reproduce hybrid cyclones in environments with high temperature and large baroclinicity. The hybrid cyclones show multiscale dynamics in which synoptic-scale baroclinic systems spawn smaller-scale tropical cyclone–like convective cores. The spectrum of cyclones is found to be nonmonotonic in the parameter space because of a two-sided effect of the vertical shear: moderate shear weakens a tropical cyclone by tilting the small-scale vortex to the downshear, while strong shear develops a large-scale vortex of an extratropical cyclone or a hybrid cyclone through warm-air advection from the south. The indices based on the energetics and the symmetric and asymmetric structures overview the different types of cyclones in the parameter space. These parameter sweep experiments provide useful information on what environment is favorable for cyclones, particularly for intermediate environments where cyclone mechanisms are yet to be fully defined.
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Breeden, Melissa L., Ryan Clare, Jonathan E. Martin, and Ankur R. Desai. "Diagnosing the Influence of a Receding Snow Boundary on Simulated Midlatitude Cyclones Using Piecewise Potential Vorticity Inversion." Monthly Weather Review 148, no. 11 (November 1, 2020): 4479–95. http://dx.doi.org/10.1175/mwr-d-20-0056.1.
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AbstractPrevious research has found a relationship between the equatorward extent of snow cover and low-level baroclinicity, suggesting a link between the development and trajectory of midlatitude cyclones and the extent of preexisting snow cover. Midlatitude cyclones are more frequent 50–350 km south of the snow boundary, coincident with weak maxima in the environmental Eady growth rate. The snow line is projected to recede poleward with increasing greenhouse gas emissions, possibly affecting the development and track of midlatitude cyclones during Northern Hemisphere winter. Detailed examination of the physical implications of a modified snow boundary on the life cycle of individual storms has, to date, not been undertaken. This study investigates the impact of a receding snow boundary on two cyclogenesis events using Weather Research and Forecasting Model simulations initialized with observed and projected future changes to snow extent as a surface boundary condition. Potential vorticity diagnosis of the modified cyclone simulations isolates how changes in surface temperature, static stability, and relative vorticity arising from the altered boundary affect the developing cyclone. We find that the surface warm anomaly associated with snow removal lowered heights near the center of the two cyclones investigated, strengthening their cyclonic circulation. However, the direct effect of snow removal is mitigated by the stability response and an indirect relative vorticity response to snow removal. Because of these opposing effects, it is suggested that the immediate effect of receding snow cover on midlatitude cyclones is likely minimal and depends on the stage of the cyclone life cycle.
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Horvath, Kristian, Yuh-Lang Lin, and Branka Ivančan-Picek. "Classification of Cyclone Tracks over the Apennines and the Adriatic Sea." Monthly Weather Review 136, no. 6 (June 1, 2008): 2210–27. http://dx.doi.org/10.1175/2007mwr2231.1.
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Abstract Cyclones that appear in the Adriatic Sea basin strongly influence the climate and weather conditions in the area. In particular, apart from the usually mild climate, cyclone activity in the Adriatic and the central Mediterranean Sea provide both the main hydrological forcing and the trigger mechanisms for a range of extreme weather phenomena. Therefore, a basic understanding of the cyclogenesis over the Adriatic Sea is essential. In particular, the classification of different types of cyclogenesis in the area is fundamental because it will help the understanding and prediction of the relevant weather phenomena. In this study, based on the analysis of the 4-yr (2002–05) operational European Centre for Medium-Range Weather Forecasts T511 dataset, various types of cyclone tracks are classified and the mesocyclogenesis areas in the vicinity of the Adriatic Basin are isolated. This analysis indicates that the following four types of cyclogenesis over the Adriatic Sea can be identified: 1) type A: cyclones connected with preexisting Genoa cyclones [with two subcategories, (A-I) continuous track: Genoa cyclones crossing over the Apennines to the Adriatic Sea, and (A-II) discontinuous track: new surface cyclones generated over the Adriatic Sea under the influence of a parent cyclone generated in the Gulf of Genoa (Genoa cyclones) and moving toward the Adriatic but blocked by the Apennines]; 2) type B: cyclones developed in situ over the Adriatic Sea without any connections with other preexisting cyclones in the surrounding area; 3) type AB: mixed types A and B cyclones, including cases where two cyclones coexist and stride over the Apennines (twin or eyeglass cyclones); and 4) type C: cyclones moving from the Mediterranean Sea, but not from the Gulf of Genoa (non-Genoa cyclones) [with 2 subcategories: (C-I) continuous track: a non-Genoa cyclone is able to cross over the Apennines to the Adriatic Sea continuously, and (C-II) discontinuous track: a non-Genoa cyclone is blocked by the Apennines and a new surface cyclone is generated over the Adriatic Sea]. The relevant dynamics of the above types of cyclones are discussed along with characteristics of the cyclones and their synoptic situations at the lower and upper troposphere.
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Hulme, Andrew L., and Jonathan E. Martin. "Synoptic- and Frontal-Scale Influences on Tropical Transition Events in the Atlantic Basin. Part II: Tropical Transition of Hurricane Karen." Monthly Weather Review 137, no. 11 (November 1, 2009): 3626–50. http://dx.doi.org/10.1175/2009mwr2803.1.
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Abstract A finescale simulation of the tropical transition of Atlantic Hurricane Karen in October 2001 is examined to determine the processes leading to the development of upshear convection and its effects on the process of tropical transition. The analysis shows that, as in marine extratropical cyclones, the area upshear of the pretransition cyclone is characterized by reduced stability. Lower-tropospheric frontogenesis leads to an intense burst of convection there and instigates three important processes that combine to produce a full-fledged tropical cyclone. First, the convection generates intense low-level vorticity on the western half of the cyclone, which quickly dominates the cyclone’s vorticity field eventually organizing the circulation into a small-scale, intense vortex. Second, the diabatically enhanced circulation hastens the isolation of the cyclone’s developing warm core by intensifying cold air advection on the northern and western sides of the storm and by placing evaporatively cooled air into the boundary layer to the south of the cyclone. Third, upshear convection vertically redistributes potential vorticity (PV) from the tropopause to the surface and introduces a component to the upper-level winds, which advects strong, shear-inducing PV gradients away from the column above the cyclone. These three processes transform the initial extratropical cyclone into a frontless vortex with tropical storm–force winds and a warm core in a low-shear environment. These features are sufficient, given a warm enough ocean surface, to allow self-amplification of the storm as a tropical cyclone. The results further blur the distinction between tropical and extratropical cyclones as many of the processes identified as important to transition are similar to those that characterize ordinary marine cyclones and the extratropical occlusion process with the key distinctions being that here the convection is stronger and the initial upper-level feature is weaker. Thus, tropical transition of strong extratropical precursors follows the canonical midlatitude cyclone life cycle with upshear convection serving as the catalyst that both induces and organizes processes that favor tropical cyclogenesis in the postmature phase.
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Mizuta, Ryo, Mio Matsueda, Hirokazu Endo, and Seiji Yukimoto. "Future Change in Extratropical Cyclones Associated with Change in the Upper Troposphere." Journal of Climate 24, no. 24 (December 15, 2011): 6456–70. http://dx.doi.org/10.1175/2011jcli3969.1.
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Abstract Future changes in Northern Hemisphere wintertime storm activity as a consequence of global warming are investigated using the AGCM of Meteorological Research Institute (MRI-AGCM) with horizontal grid sizes of 60 and 20 km. A future (2075–99) climate experiment, in which the change in sea surface temperature (SST) derived from the Coupled Model Intercomparison Project phase 3 (CMIP3) multimodel ensemble mean is added to observed SST, is compared with a present-day (1979–2003) climate experiment. Results of three-member simulations using the 60-km model are presented. A single simulation using the 20-km model is also presented, showing that similar results are obtained. In the future climate experiment, the number of intense cyclones (sea level pressure below 980 hPa) shows a significant increase whereas the number of total cyclones shows a significant decrease, similar to the results obtained from the CMIP3 models themselves. The increase in intense cyclones is seen on the polar side and downstream side of Atlantic and Pacific storm tracks. At the same time, the growth rate of the cyclones increases in areas upstream of these regions. For the regions with the increasing growth rate, a high correlation is seen between the growth rate of the surface cyclones and upper-tropospheric zonal wind at a monthly-mean time scale. Months of high cyclone growth rate with strong zonal wind in these regions become more frequent, and months of low cyclone growth rate with weak zonal wind become less frequent. One of the possibilities that can explain this relationship is changes in the wave-breaking pattern, that is, a decrease in wave breakings in areas of cyclonic shear and an increase in wave breakings in areas of anticyclonic shear. Associated with these changes, rapid cyclone developments are more commonly seen, and weak, long-lived cyclones become less frequent.
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Picornell, M. A., J. Campins, and A. Jansà. "Detection and thermal description of medicanes from numerical simulation." Natural Hazards and Earth System Sciences Discussions 1, no. 6 (December 12, 2013): 7417–47. http://dx.doi.org/10.5194/nhessd-1-7417-2013.
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Abstract. Tropical-like cyclones rarely affect the Mediterranean region and they can produce strong winds and heavy precipitations. These warm-core cyclones, called MEDICANES (MEDIterranean hurriCANES), are small size, develop over the sea and are infrequent. For these reasons, the detection and forecast of medicanes are a difficult task and many efforts have been devoted to identify them. The goals of this work are to contribute to a proper description of these structures and to develop some criteria to identify medicanes from numerical weather prediction (NWP) model outputs. To do that, existing methodologies for detecting, characterizating and tracking cyclones have been adapted to small-scale intense cyclonic perturbations. First, a mesocyclone detection and tracking algorithm has been modified to select intense cyclones. Next, the parameters that define the Hart's cyclone phase diagram are tuned and calculated to examine their thermal structure. Four well-known medicane events have been described from numerical simulation outputs of the ECMWF model. The predicted cyclones and their evolution have been validated against available observational data and numerical analyses from literature.
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Gray, Suzanne L., Kevin I. Hodges, Jonathan L. Vautrey, and John Methven. "The role of tropopause polar vortices in the intensification of summer Arctic cyclones." Weather and Climate Dynamics 2, no. 4 (December 23, 2021): 1303–24. http://dx.doi.org/10.5194/wcd-2-1303-2021.
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Abstract. Human activity in the Arctic is increasing as new regions become accessible, with a consequent need for improved understanding of hazardous weather there. Arctic cyclones are the major weather systems affecting the Arctic environment during summer, including the sea ice distribution. Mesoscale to synoptic-scale tropopause polar vortices (TPVs) frequently occur in polar regions and are a proposed mechanism for Arctic cyclone genesis and intensification. However, while the importance of pre-existing tropopause-level features for cyclone development, as well as being an integral part of the three-dimensional mature cyclone structure, is well established in the mid-latitudes, evidence of the importance of pre-existing TPVs for Arctic cyclone development is mainly limited to a few case studies. Here we examine the extent to which Arctic cyclone growth is coupled to TPVs by analysing a climatology of summer Arctic cyclones and TPVs produced by tracking both features in the latest ECMWF reanalysis (ERA5). The annual counts of Arctic cyclones and TPVs are significantly correlated for features with genesis either within or outside the Arctic, implying that TPVs have a role in the development of Arctic cyclones. However, only about one-third of Arctic cyclones have their genesis or intensify while a TPV of Arctic origin is (instantaneously) within about twice the Rossby radius of the cyclone centre. Consistent with the different track densities of the full sets of Arctic cyclones and TPVs, cyclones with TPVs within range throughout their intensification phase (matched cyclones) track preferentially over the Arctic Ocean along the North American coastline and Canadian Arctic Archipelago. In contrast, cyclones intensifying distant from any TPV (unmatched cyclones) track preferentially along the northern coast of Eurasia. Composite analysis reveals the presence of a distinct relative vorticity maximum at and above the tropopause level associated with the TPV throughout the intensification period for matched cyclones and that these cyclones have a reduced upstream tilt compared to unmatched cyclones. Interaction of cyclones with TPVs has implications for the predictability of Arctic weather, given the long lifetime but relatively small spatial scale of TPVs compared with the density of the polar observation network.
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Reutter, P., B. Škerlak, M. Sprenger, and H. Wernli. "Stratosphere–troposphere exchange (STE) in the vicinity of North Atlantic cyclones." Atmospheric Chemistry and Physics Discussions 15, no. 2 (January 27, 2015): 2535–75. http://dx.doi.org/10.5194/acpd-15-2535-2015.
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Abstract. It is well known that the storm tracks are a preferred region of stratosphere–troposphere exchange (STE), but a systematic and climatological investigation of the connection between cyclones and STE has not yet been performed. We use two established ERA-Interim climatologies of STE and cyclones for the years 1979–2011 to quantify the amount of STE that occurs during the life cycle of North Atlantic cyclones. A Lagrangian method serves to identify individual STE events, and a sophisticated cyclone identification tool detects cyclones, their shape and size from the sea-level pressure field. Combining the two data sets reveals that roughly half of the total STE in the North Atlantic occurs in the vicinity of cyclones and that both downward and upward fluxes of mass across the tropopause (STT and TST, respectively) are more intense in deeper cyclones (lower minimum pressure) compared to less intense cyclones. In summer, STT and TST in the vicinity of cyclones are almost equal; in the other seasons, STT is larger by 15–45%. Cross-tropopause mass fluxes are enhanced by a factor of about two compared to climatology when a cyclone is present. On average, STE is strongest during the mature phase of cyclones, i.e., in a 24 h time window around the time of maximum intensity. Systematic patterns of exchange locations relative to the cyclone centre are identified via composite analysis and shed light on the different characteristics of STT and TST. During cyclone intensification and in the mature stage, TST is mainly confined to the cyclone centre, whereas STT occurs mainly in a region further southwest. During the decay of the cyclones, both STT and TST are most frequent close the cyclone centre, in a region with a~fairly low tropopause.
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Reutter, P., B. Škerlak, M. Sprenger, and H. Wernli. "Stratosphere–troposphere exchange (STE) in the vicinity of North Atlantic cyclones." Atmospheric Chemistry and Physics 15, no. 19 (October 2, 2015): 10939–53. http://dx.doi.org/10.5194/acp-15-10939-2015.
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Abstract. It is well known that the storm tracks are a preferred region of stratosphere–troposphere exchange (STE), but a systematic and climatological investigation of the connection between cyclones and STE has not yet been performed. We use two ERA-Interim climatologies of STE and cyclones for the years 1979–2011 to quantify the amount of STE that occurs during the life cycle of North Atlantic cyclones. A Lagrangian method serves to identify individual STE events, and a sophisticated cyclone identification tool detects cyclones, their shape and size from the sea-level pressure (SLP) field and from geopotential height anomalies at 300–700 hPa. Combining the two data sets reveals that roughly 50–60 % of the total STE in the North Atlantic occurs in the vicinity of cyclones and that both downward and upward fluxes of mass across the tropopause (STT and TST, respectively) are more intense in deeper cyclones (lower minimum SLP) compared to less intense cyclones. In summer, STT and TST in the vicinity of cyclones are almost equal; in the other seasons, STT is larger by 25–60 %. Compared to climatology, cross-tropopause mass fluxes are enhanced by a factor of about 1.29 and 1.06 for STT and TST, respectively, when a cyclone is present. On average, STE is strongest during the mature phase of cyclones, i.e., in a 24 h time window around the time of maximum intensity. Systematic patterns of exchange locations relative to the cyclone centre are identified via composite analysis and shed light on the different characteristics of STT and TST. During cyclone intensification and in the mature stage, TST is mainly confined to the cyclone centre, whereas STT occurs mainly in a region further southwest. During the decay of the cyclones, both STT and TST are most frequent close to the cyclone centre, in a region with a fairly low tropopause.
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Lloyd, Ian D., and Gabriel A. Vecchi. "Observational Evidence for Oceanic Controls on Hurricane Intensity." Journal of Climate 24, no. 4 (February 15, 2011): 1138–53. http://dx.doi.org/10.1175/2010jcli3763.1.
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Abstract The influence of oceanic changes on tropical cyclone activity is investigated using observational estimates of sea surface temperature (SST), air–sea fluxes, and ocean subsurface thermal structure during the period 1998–2007. SST conditions are examined before, during, and after the passage of tropical cyclones, through Lagrangian composites along cyclone tracks across all ocean basins, with particular focus on the North Atlantic. The influence of translation speed is explored by separating tropical cyclones according to the translation speed divided by the Coriolis parameter. On average for tropical cyclones up to category 2, SST cooling becomes larger as cyclone intensity increases, peaking at 1.8 K in the North Atlantic. Beyond category 2 hurricanes, however, the cooling no longer follows an increasing monotonic relationship with intensity. In the North Atlantic, the cooling for stronger hurricanes decreases, while in other ocean basins the cyclone-induced cooling does not significantly differ from category 2 to category 5 tropical cyclones, with the exception of the South Pacific. Since the SST response is nonmonotonic, with stronger cyclones producing more cooling up to category 2, but producing less or approximately equal cooling for categories 3–5, the observations indicate that oceanic feedbacks can inhibit intensification of cyclones. This result implies that large-scale oceanic conditions are a control on tropical cyclone intensity, since they control oceanic sensitivity to atmospheric forcing. Ocean subsurface thermal data provide additional support for this dependence, showing weaker upper-ocean stratification for stronger tropical cyclones. Intensification is suppressed by strong ocean stratification since it favors large SST cooling, but the ability of tropical cyclones to intensify is less inhibited when stratification is weak and cyclone-induced SST cooling is small. Thus, after accounting for tropical cyclone translation speeds and latitudes, it is argued that reduced cooling under extreme tropical cyclones is the manifestation of the impact of oceanic conditions on the ability of tropical cyclones to intensify.
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D. P, Poojith K., Somashekhara ., and Dasharatha P. Angadi. "Assessing the impact of cyclonic storm Tauktae on shoreline change in Mangaluru coast using geospatial technology." Scientific Temper 15, no. 01 (March 15, 2024): 1685–88. http://dx.doi.org/10.58414/scientifictemper.2024.15.1.16.
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Cyclones are natural events that occur with atmospheric pressure variations. Compared to the eastern coast of India, the western coast has less cyclonic activity. Even though some of the cyclonic events turn into severe cyclonic storms and cause a huge impact on ecological and anthropogenic activities. This research focuses on the impact of cyclone Tauktae on the Mangalore coast. Cyclone Tauktae, one of the most powerful to pass through coastal Karnataka, caused significant damages, affecting 121 villages and resulting in four casualties. Utilizing geospatial techniques, this study employs Sentinel-2 satellite images to analyze shoreline changes during pre and post-cyclone Tauktae. A GIS technique involves the extraction of shorelines using 10-meter resolution images, with manual digitization excluding natural and man-made structures. Transect lines are generated with the help of DSAS to measure shoreline movement, distinguishing accretion and erosion. Rainfall conditions during the cyclone period are mapped using gridded rainfall data. The study area, encompassing ten coastal villages from Someshwara to Sasihithlu, is characterized by its vulnerability to cyclones. Results reveal substantial shoreline changes, with notable erosion in central and northern Mangaluru, Tannirbavi, and Hosabettu. Accretion is observed in south Someshwara and north Sashihitlu. Rainfall patterns are analyzed using Persian CCS gridded data, depicting the dynamic nature of precipitation during the cyclonic event. This research contributes valuable insights into the short-term effects of cyclonic storms on shorelines, emphasizing the importance of geospatial techniques for coastal management. The findings serve as a foundation for mitigating cyclonic impacts and enhancing resilience in the Mangalore coast, aiding future coastal management strategies
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Pfahl, Stephan, Paul A. O’Gorman, and Martin S. Singh. "Extratropical Cyclones in Idealized Simulations of Changed Climates." Journal of Climate 28, no. 23 (December 1, 2015): 9373–92. http://dx.doi.org/10.1175/jcli-d-14-00816.1.
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Abstract Cyclones are a key element of extratropical weather and frequently lead to extreme events like wind storms and heavy precipitation. Understanding potential changes of cyclone frequency and intensity is thus essential for a proper assessment of climate change impacts. Here the behavior of extratropical cyclones under strongly varying climate conditions is investigated using idealized climate model simulations in an aquaplanet setup. A cyclone tracking algorithm is applied to assess various statistics of cyclone properties such as intensity, size, lifetime, displacement velocity, and deepening rates. In addition, a composite analysis of intense cyclones is performed. In general, the structure of extratropical cyclones in the idealized simulations is very robust, and changes in major cyclone characteristics are relatively small. Median cyclone intensity, measured in terms of minimum sea level pressure and lower-tropospheric relative vorticity, has a maximum in simulations with global mean temperature slightly warmer than present-day Earth, broadly consistent with the behavior of the eddy kinetic energy analyzed in previous studies. Maximum deepening rates along cyclone tracks behave similarly and are in agreement with linear quasigeostrophic growth rates if the effect of latent heat release on the stratification is taken into account. In contrast to moderate cyclones, the relative vorticity of intense cyclones continues to increase with warming to substantially higher temperatures, and this is associated with enhanced lower-tropospheric potential vorticity anomalies likely caused by increased diabatic heating. Moist processes may, therefore, lead to the further strengthening of intense cyclones in warmer climates even if cyclones weaken on average.
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Hakim, Gregory J., and Amelia K. Canavan. "Observed Cyclone–Anticyclone Tropopause Vortex Asymmetries." Journal of the Atmospheric Sciences 62, no. 1 (January 1, 2005): 231–40. http://dx.doi.org/10.1175/jas-3353.1.
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Abstract Relatively little is known about coherent vortices near the extratropical tropopause, even with regard to basic facts about their frequency of occurrence, longevity, and structure. This study addresses these issues through an objective census of observed tropopause vortices. The authors test a hypothesis regarding vortex-merger asymmetry where cyclone pairs are repelled and anticyclone pairs are attracted by divergent flow due to frontogenesis. Emphasis is placed on arctic vortices, where jet stream influences are weaker, in order to facilitate comparisons with earlier idealized numerical simulations. Results show that arctic cyclones are more numerous, persistent, and stronger than arctic anticyclones. An average of 15 cyclonic vortices and 11 anticyclonic vortices are observed per month, with maximum frequency of occurrence for cyclones (anticyclones) during winter (summer). There are are about 47% more cyclones than anticyclones that survive at least 4 days, and for longer lifetimes, 1-day survival probabilities are nearly constant at 65% for cyclones, and 55% for anticyclones. Mean tropopause potential-temperature amplitude is 13 K for cyclones and 11 K for anticyclones, with cyclones exhibiting a greater tail toward larger values. An analysis of close-proximity vortex pairs reveals divergence between cyclones and convergence between anticyclones. This result agrees qualitatively with previous idealized numerical simulations, although it is unclear to what extent the divergent circulations regulate vortex asymmetries.