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Journal articles on the topic 'Storm morphology'
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1
Stein, Thorwald H. M., Robin J. Hogan, Kirsty E. Hanley, John C. Nicol, Humphrey W. Lean, Robert S. Plant, Peter A. Clark, and Carol E. Halliwell. "The Three-Dimensional Morphology of Simulated and Observed Convective Storms over Southern England." Monthly Weather Review 142, no. 9 (September 2014): 3264–83. http://dx.doi.org/10.1175/mwr-d-13-00372.1.
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A set of high-resolution radar observations of convective storms has been collected to evaluate such storms in the Met Office Unified Model during the Dynamical and Microphysical Evolution of Convective Storms (DYMECS) project. The 3-GHz Chilbolton Advanced Meteorological Radar was set up with a scan-scheduling algorithm to automatically track convective storms identified in real time from the operational rainfall radar network. More than 1000 storm observations gathered over 15 days in 2011 and 2012 are used to evaluate the model under various synoptic conditions supporting convection. In terms of the detailed three-dimensional morphology, storms in the 1500-m grid length simulations are shown to produce horizontal structures a factor of 1.5–2 wider compared to radar observations. A set of nested model runs at grid lengths down to 100 m show that the models converge in terms of storm width, but the storm structures in the simulations with the smallest grid lengths are too narrow and too intense compared to the radar observations. The modeled storms were surrounded by a region of drizzle without ice reflectivities above 0 dBZ aloft, which was related to the dominance of ice crystals and was improved by allowing only aggregates as an ice particle habit. Simulations with graupel outperformed the standard configuration for heavy-rain profiles, but the storm structures were a factor of 2 too wide and the convective cores 2 km too deep.
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Marmoush, Ramy Y., and Ryan P. Mulligan. "OBSERVATIONS OF BEACH-DUNE MORPHOGOLICAL RESPONSE TO STORM WAVES USING LIDAR BATHYMETRIC MAPPING IN A WAVE BASIN." Coastal Engineering Proceedings, no. 36 (December 30, 2018): 5. http://dx.doi.org/10.9753/icce.v36.sediment.5.
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Waves during major storms can cause significant changes to coastal morphology (Lee et al., 1998). The beach-dune system is known to be highly vulnerable to erosion when the wave run-up exceeds the threshold of the base of the dune in the collision regime, according to the Storm Impact scale defined by Sallenger (2000). Detailed bathymetric measurements are very difficult to obtain during storms due to the hazardous wave conditions. However, bathymetric surveys can be easily and intermittently performed during smaller scale physical model experiments (e.g., Hamilton et al., 2001) and high resolution can be achieved using laser scanning with Light Detection and Ranging (LIDAR) sensors (Smith et al., 2017). In the present study, a laboratory experiment of beach-dune morphology change is conducted in a rectangular wave basin that has recently been used to simulate erosion of a 2-dimensional sand dune (Berard et al., 2017). The objective of the present study is to investigate the 3-dimensional morphologic response of a sand beach-dune system to storm waves approaching at an oblique angle.
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Markowski, Paul, and Yvette Richardson. "On the Classification of Vertical Wind Shear as Directional Shear versus Speed Shear." Weather and Forecasting 21, no. 2 (April 1, 2006): 242–47. http://dx.doi.org/10.1175/waf897.1.
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Abstract Vertical wind shear is commonly classified as “directional” or “speed” shear. In this note, these classifications are reviewed and their relevance discussed with respect to the dynamics of convective storms. In the absence of surface drag, storm morphology and evolution only depend on the shape and length of a hodograph, on which the storm-relative winds depend; that is, storm characteristics are independent of the translation and rotation of a hodograph. Therefore, traditional definitions of directional and speed shear are most relevant when applied to the storm-relative wind profile.
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Li, Honghai, Lihwa Lin, and Kelly A. Burks-Copes. "NUMERICAL MODELING OF COASTAL INUNDATION AND SEDIMENTATION BY STORM SURGE, TIDES, AND WAVES AT NORFOLK, VIRGINIA, USA." Coastal Engineering Proceedings 1, no. 33 (December 15, 2012): 54. http://dx.doi.org/10.9753/icce.v33.sediment.54.
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A nearshore hydrodynamic and sediment transport model was developed to simulate synthetic storms with design SLR scenarios surrounding the military installations in Norfolk, Virginia. Foreseeable risk and effect of storm surge damage accompanied by waves, tides, and Sea Level Rise (SLR) were examined. The final results include the evaluation of impacts for five SLR (0.0, 0.5, 1.0, 1.5, and 2.0 m) and three storm conditions (50-yr, 100-yr return tropical storms, and a winter storm). Associated with the storm surge and SLR, extensive inundation will occur at the Naval Station Norfolk, approximately 70-80% of the Naval Station Norfolk under the 2-m SLR scenario. The calculated morphology changes indicate that the sediment movement mostly occurs in the navigation channels and the maximum depth changes are more than 3.0 m along the channels. The bed volume changes show that the storms induce a net volume loss within the channel area, an indication of channel flushing in the study area.
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Burns, A. G., T. L. Killeen, and R. G. Roble. "Thermospheric heating away from the auroral oval during geomagnetic storms." Canadian Journal of Physics 70, no. 7 (July 1, 1992): 544–52. http://dx.doi.org/10.1139/p92-089.
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Model predictions indicate that the high-latitude thermosphere near the F2 peak undergoes strong heating during geomagnetic storms. Experimental studies at middle and equatorial latitudes have indicated that heating occurs during geomagnetic storms, although the overall morphology of these temperature changes is not clear. In this paper we use data from the DE-2 (dynamics explorer) satellite to study this morphology at middle and high latitudes, and then use a simulation of the November 24, 1982 storm, by the NCAR–TIGCM, to compare model output and data on a "one-on-one" basis for an individual orbit in the middle of this storm. Agreement between model and data is good in the winter hemisphere, so we use a thermodynamic diagnostic processor to make a preliminary investigation of the mechanisms by which geomagnetic storms cause temperature increases at lower latitudes. The major conclusions from this work are (i) unlike compositional changes, thermospheric temperature changes do not display a long "tail" into the post-midnight, mid-latitude region; (ii) the pattern of heating during geomagnetic storms is complex, a result of the complicated physical processes that occur during geomagnetic storms; (iii) heating due to advection is approximately balanced by expansion of the gas and downward heat conduction in the postmidnight region; (iv) model predictions for this storm indicate that the greatest temperature increase at 40° N is seen in the dawn sector; (v) early in the storm the strongest compressional heating at latitudes near 40° N is found in the premidnight region, where parcels of air are slowed by sunward ion convection, and consequently converge causing downward winds; (vi) compressional heating also occurs in the afternoon, in a region where expansion of the gas, and hence cooling, occurs during quiet geomagnetic times.
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Palermo, Rose V., Anastasia Piliouras, Travis E. Swanson, Andrew D. Ashton, and David Mohrig. "The effects of storms and a transient sandy veneer on the interannual planform evolution of a low-relief coastal cliff and shore platform at Sargent Beach, Texas, USA." Earth Surface Dynamics 9, no. 5 (September 8, 2021): 1111–23. http://dx.doi.org/10.5194/esurf-9-1111-2021.
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Abstract. Coastal cliff erosion is alongshore-variable and episodic, with retreat rates that depend upon sediment as either tools of abrasion or protective cover. However, the feedbacks between coastal cliff planform morphology, retreat rate, and sediment cover are poorly quantified. This study investigates Sargent Beach, Texas, USA, at the annual to interannual scale to explore (1) the relationship between temporal and spatial variability in cliff retreat rate, roughness, and sinuosity and (2) the response of retreat rate and roughness to changes in sand and shell hash cover of the underlying mud substrate as well as the impact of major storms using field measurements of sediment cover, erosion, and aerial images to measure shore platform morphology and retreat. A storm event in 2009 increased the planform roughness and sinuosity of the coastal cliff at Sargent Beach. Following the storm, aerial-image-derived shorelines with annual resolution show a decrease in average alongshore erosion rates from 12 to 4 m yr−1, coincident with a decrease in shoreline roughness and sinuosity (smoothing). Like the previous storm, a storm event in 2017 increased the planform roughness and sinuosity of the cliff. Over shorter timescales, monthly retreat of the sea cliff occurred only when the platform was sparsely covered with sediment cover on the shore platform, indicating that the tools and cover effects can significantly affect short-term erosion rates. The timescale to return to a smooth shoreline following a storm or roughening event, given a steady-state erosion rate, is approximately 24 years, with the long-term rate suggesting a maximum of ∼107 years until Sargent Beach breaches, compromising the Gulf Intracoastal Waterway (GIWW) under current conditions and assuming no future storms or intervention. The observed retreat rate varies, both spatially and temporally, with cliff face morphology, demonstrating the importance of multi-scale measurements and analysis for interpretation of coastal processes and patterns of cliff retreat.
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Mendillo, M., and C. Narvaez. "Ionospheric storms at geophysically-equivalent sites – Part 1: Storm-time patterns for sub-auroral ionospheres." Annales Geophysicae 27, no. 4 (April 7, 2009): 1679–94. http://dx.doi.org/10.5194/angeo-27-1679-2009.
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Abstract. The systematic study of ionospheric storms has been conducted primarily with groundbased data from the Northern Hemisphere. Significant progress has been made in defining typical morphology patterns at all latitudes; mechanisms have been identified and tested via modeling. At higher mid-latitudes (sites that are typically sub-auroral during non-storm conditions), the processes that change significantly during storms can be of comparable magnitudes, but with different time constants. These include ionospheric plasma dynamics from the penetration of magnetospheric electric fields, enhancements to thermospheric winds due to auroral and Joule heating inputs, disturbance dynamo electrodynamics driven by such winds, and thermospheric composition changes due to the changed circulation patterns. The ~12° tilt of the geomagnetic field axis causes significant longitude effects in all of these processes in the Northern Hemisphere. A complementary series of longitude effects would be expected to occur in the Southern Hemisphere. In this paper we begin a series of studies to investigate the longitudinal-hemispheric similarities and differences in the response of the ionosphere's peak electron density to geomagnetic storms. The ionosonde stations at Wallops Island (VA) and Hobart (Tasmania) have comparable geographic and geomagnetic latitudes for sub-auroral locations, are situated at longitudes close to that of the dipole tilt, and thus serve as our candidate station-pair choice for studies of ionospheric storms at geophysically-comparable locations. They have an excellent record of observations of the ionospheric penetration frequency (foF2) spanning several solar cycles, and thus are suitable for long-term studies. During solar cycle #20 (1964–1976), 206 geomagnetic storms occurred that had Ap≥30 or Kp≥5 for at least one day of the storm. Our analysis of average storm-time perturbations (percent deviations from the monthly means) showed a remarkable agreement at both sites under a variety of conditions. Yet, small differences do appear, and in systematic ways. We attempt to relate these to stresses imposed over a few days of a storm that mimic longer term morphology patterns occurring over seasonal and solar cycle time spans. Storm effects versus season point to possible mechanisms having hemispheric differences (as opposed to simply seasonal differences) in how solar wind energy is transmitted through the magnetosphere into the thermosphere-ionosphere system. Storm effects versus the strength of a geomagnetic storm may, similarly, be related to patterns seen during years of maximum versus minimum solar activity.
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Ellis, Jean T., Michelle E. Harris, Mayra A. Román-Rivera, J. Brianna Ferguson, Peter A. Tereszkiewicz, and Sean P. McGill. "Application of the Saffir-Simpson Hurricane Wind Scale to Assess Sand Dune Response to Tropical Storms." Journal of Marine Science and Engineering 8, no. 9 (September 1, 2020): 670. http://dx.doi.org/10.3390/jmse8090670.
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Over one-third of the Earth’s population resides or works within 200 km of the coast. The increasing threat of coastal hazards with predicted climate change will impact many global citizens. Coastal dune systems serve as a natural first line of defense against rising sea levels and coastal storms. This study investigated the volumetric changes of two dune systems on Isle of Palms, South Carolina, USA prior to and following Hurricanes Irma (2017) and Florence (2018), which impacted the island as tropical storms with different characteristics. Irma had relatively high significant wave heights and precipitation, resulting in an average 39% volumetric dune loss. During Florence, a storm where precipitation was low and winds were moderate, net volumetric dune loss averaged 3%. The primary driving force causing dune change during Irma was water (precipitation and storm surge), and during Florence, it was wind (aeolian transport). We suggest that the application of the Saffir-Simpson Hurricane Wind Scale classifications should be reconsidered because different geomorphic responses were measured, despite Irma and Florence both being designated as tropical storms. Site-specific pre- and post-storm studies of the dune morphology and site-specific meteorological measurements of the storm (wind characteristics, storm surge, precipitation) are critically needed.
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Mickey, Rangley C., Patricia S. Dalyander, Robert McCall, and Davina L. Passeri. "Sensitivity of Storm Response to Antecedent Topography in the XBeach Model." Journal of Marine Science and Engineering 8, no. 10 (October 21, 2020): 829. http://dx.doi.org/10.3390/jmse8100829.
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Antecedent topography is an important aspect of coastal morphology when studying and forecasting coastal change hazards. The uncertainty in morphologic response of storm-impact models and their use in short-term hazard forecasting and decadal forecasting is important to account for when considering a coupled model framework. This study provided a methodology to investigate uncertainty of profile response within the storm impact model XBeach related to varying antecedent topographies. A parameterized island Gaussian fit (PIGF) model generated an idealized baseline profile and a suite of idealized profiles that vary specific characteristics based on collated observed LiDAR data from Dauphin Island, AL, USA. Six synthetic storm scenarios were simulated on each of the idealized profiles with XBeach in both 1- and 2-dimensional setups and analyzed to determine the morphological response and uncertainty related to the varied antecedent topographies. Profile morphologic response tends to scale with storm magnitude but among the varied profiles there is greater uncertainty in profile response to the medium range storm scenarios than to the low and high magnitude storm scenarios. XBeach can be highly sensitive to morphologic thresholds, both antecedent and time-varying, especially with regards to beach slope.
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Lucrezi, Serena, Thomas A. Schlacher, and Wayne Robinson. "Can storms and shore armouring exert additive effectson sandy-beach habitats and biota?" Marine and Freshwater Research 61, no. 9 (2010): 951. http://dx.doi.org/10.1071/mf09259.
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Increased storminess is a likely consequence of global climate change; its effects may be most dramatic on coasts dominated by sandy beaches. This scenario demands that the impacts of storms and the role of armouring structures, constructed as storm defences, are better understood. Here, we assess how a relatively small storm affected beach morphology and macrobenthos, and whether a seawall can modulate such impacts. The study system was a small (<1.5 km long) beach, bisected into parts with and without a seawall. The beach became narrower and steeper during the storm, when 26% of the subaerial sediment prism eroded from the armoured section; sand losses on the unarmoured part were one-fifth of those on the armoured part. Densities of ghost crabs (Ocypode) dropped significantly (36%) and were to some extent modulated by shore armouring; losses were high (62%) just seawards of the seawall where post-storm densities remained consistently lower. There was no ecological recovery in the short term, with most (83%) post-storm density values of crabs being lower, and crab counts in front of the seawall being depressed up to 3 months after the storm. Seawalls can change the resilience of beaches to storms, which may result in stronger ecological effects on armoured coasts.
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Xuan Tinh, Nguyen, Magnus Larson, Chantal Donnelly, and Hitoshi Tanaka. "LABORATORY EXPERIMENT ON CROSS-SHORE BARRIER SPIT EVOLUTION BY STORM DYNAMICS." Coastal Engineering Proceedings 1, no. 32 (January 19, 2011): 32. http://dx.doi.org/10.9753/icce.v32.sediment.32.
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Every year there are many severe storms occurring around the world, in general, and in Japan, in particular. The occurrence of storms is expected to increase because of the global warming effects. An increasing wave height together with a rising mean water level during a storm create a high possibility for waves to overtop the beach crest causing a lot of sediment to be eroded to offshore areas or deposited in the inland direction. The study of the barrier island response to storms has therefore become very important in terms of sediment transport and beach morphology change, as well as damage to nearshore structures due to runup overwash and inundation overwash. However, changes in the beach profile and prevailing sediment transport mechanisms during a real event are difficult to obtain. Thus, laboratory studies are necessary to conduct. This study presents a laboratory experiment on the impact of storms on a sandy barrier islands. The main aim is to investigate the entire barrier island (or sand spit) response due to storm conditions considering the increase in water level due to storm surge. Also, further development of an analytical model for barrier profile change caused by runup overwash is presented and obtained results overall captured order-of-magnitude barrier face retreat and volume changes after the storm.
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Ghofrani, Zahra, Victor Sposito, and Robert Faggian. "Designing a Pond and Evaluating its Impact Upon Storm-Water Quality and Flow: A Case Study in Rural Australia." Ecological Chemistry and Engineering S 26, no. 3 (September 1, 2019): 475–91. http://dx.doi.org/10.1515/eces-2019-0036.
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Abstract Storm-water management is a common concern in rural catchments where development-related growth causes increases of storm-water flows. Greater magnitude and frequency of storm-water create greater challenges for mitigating storm-water damage and improving water quality. The concept of Blue-Green Infrastructure (BGI) as a solution incorporates a wide range of applicable components with the aim of minimizing the effect of catchment development on flow regimes without changing the watershed morphology. BGI components manage storm-water by decreasing impermeable cover and expanding natural and semi-natural systems to store water or recharge and filter storm-water into the ground. In this paper, guidelines for designing a pond as a component of BGI are provided and, configuration and size of the pond are determined. Moreover, the impacts of the designed pond on storm-water peak flow and quality are assessed for the Tarwin catchment, State of Victoria, Australia. The results indicate that the introduction of the pond would have reduced outfall inflow by 94 % and would have achieved the reduction of 88.3, 75.5 and 50.7 % for total suspended solids, total phosphorus, and total nitrogen respectively, during the extreme weather event in June 2012.
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Troch, Peter A., Francois P. De Troch, Marco Mancini, and Eric F. Wood. "Stream network morphology and storm response in humid catchments." Hydrological Processes 9, no. 5-6 (June 1995): 575–87. http://dx.doi.org/10.1002/hyp.3360090508.
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Nesbitt, Stephen W., Robert Cifelli, and Steven A. Rutledge. "Storm Morphology and Rainfall Characteristics of TRMM Precipitation Features." Monthly Weather Review 134, no. 10 (October 1, 2006): 2702–21. http://dx.doi.org/10.1175/mwr3200.1.
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Abstract Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR), TRMM Microwave Imager (TMI), and Visible and Infrared Scanner (VIRS) observations within the Precipitation Feature (PF) database have been analyzed to examine regional variability in rain area and maximum horizontal extent of rainfall features, and role of storm morphology on rainfall production (and thus modes where vertically integrated heating occurs). Particular attention is focused on the sampling geometry of the PR and the resulting impact on PF statistics across the global Tropics. It was found that 9% of rain features extend to the edge of the PR swath, with edge features contributing 42% of total rainfall. However, the area (maximum dimension) distribution of PR features is similar to the wider-swath TMI up until a truncation point of nearly 30 000 km2 (250 km), so a large portion of the feature size spectrum may be examined using the PR as with past ground-based studies. This study finds distinct differences in land and ocean storm morphology characteristics, which lead to important differences in rainfall modes regionally. A larger fraction of rainfall comes from more horizontally and vertically developed PFs over land than ocean due to the lack of shallow precipitation in both relative and absolute frequency of occurrence, with a trimodal distribution of rainfall contribution versus feature height observed over the ocean. Mesoscale convective systems (MCSs) are found to be responsible for up to 90% of rainfall in selected land regions. Tropicswide, MCSs are responsible for more than 50% of rainfall in almost all regions with average annual rainfall exceeding 3 mm day−1. Characteristic variability in the contribution of rainfall by feature type is shown over land and ocean, which suggests new approaches for improved convective parameterizations.
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Falk, Nicholas M., Adele L. Igel, and Matthew R. Igel. "The Relative Impact of Ice Fall Speeds and Microphysics Parameterization Complexity on Supercell Evolution." Monthly Weather Review 147, no. 7 (June 14, 2019): 2403–15. http://dx.doi.org/10.1175/mwr-d-18-0417.1.
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Abstract The use of bin or bulk microphysics schemes in model simulations frequently produces large changes in the simulated storm and precipitation characteristics, but it is still unclear which aspects of these schemes give rise to these changes. In this study, supercell simulations using either a bin or a double-moment bulk microphysics scheme are conducted with the Regional Atmospheric Modeling System (RAMS). The two simulations produce very different storm morphologies. An additional simulation is run for each scheme in which the diameter–fall speed relationships for ice hydrometeors are modified to be similar to those used by the other scheme. When fall speed relationships are homogenized, the two parameterization schemes simulate similar storm morphology. Therefore, despite the use of largely dissimilar approaches to parameterizing microphysics, the difference in storm morphology is found to be related to the choice of diameter–fall speed relationships for ice hydrometeors. This result is investigated further to understand why. Higher fall speeds lead to higher mixing ratios of hydrometeors at low levels and thus more melting. Consequently, stronger downdrafts and cold pools exist in the high fall speed storms, and these stronger cold pools lead to storm splitting and the intensification of a left mover. The results point to the importance of hydrometeor fall speed on the evolution of supercells. It is also suggested that caution be used when comparing the response of a cloud model to different classes of microphysics schemes since the assumptions made by the schemes may be more important than the scheme class itself.
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Biqiang, Zhao, Wan Weixing, Liu Libo, and Mao Tian. "Morphology in the total electron content under geomagnetic disturbed conditions: results from global ionosphere maps." Annales Geophysicae 25, no. 7 (July 30, 2007): 1555–68. http://dx.doi.org/10.5194/angeo-25-1555-2007.
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Abstract. Using 8-year global ionosphere maps (GIMs) of TEC products from the Jet Propulsion Laboratory (JPL), we make a statistical study on the morphology of the global ionospheric behaviors with respect to the geomagnetic disturbances. Results show that the behaviors of TEC during geomagnetic storm present clear seasonal and local time variations under geomagnetic control in a similar way as those of NmF2 (Field and Rishbeth, 1997). A negative phase of TEC occurs with high probability in the summer hemisphere and most prominent near the geomagnetic poles, while a positive phase is obvious in the winter hemisphere and in the far pole region. A negative storm effect toward lower latitudes tends to occur from post-midnight to the morning sector and recedes to high latitude in the afternoon. A positive storm effect is separated by geomagnetic latitudes and magnetic local time. Furthermore, ionospheric responses at different local time sectors with respect to the storm commencement shows very different developing processes corresponding to the evolution of the geomagnetic storm. A daytime positive storm effect is shown to be more prominent in the American region than those in the Asian and European regions, which may suggest a longitudinal effect of the ionospheric storm.
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Han, Lei, Shengxue Fu, Lifeng Zhao, Yongguang Zheng, Hongqing Wang, and Yinjing Lin. "3D Convective Storm Identification, Tracking, and Forecasting—An Enhanced TITAN Algorithm." Journal of Atmospheric and Oceanic Technology 26, no. 4 (April 1, 2009): 719–32. http://dx.doi.org/10.1175/2008jtecha1084.1.
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Abstract Storm identification, tracking, and forecasting make up an essential part of weather radar and severe weather surveillance operations. Existing nowcasting algorithms using radar data can be generally classified into two categories: centroid and cross-correlation tracking. Thunderstorm Identification, Tracking, and Nowcasting (TITAN) is a widely used centroid-type nowcasting algorithm based on this paradigm. The TITAN algorithm can effectively identify, track, and forecast individual convective storm cells, but TITAN tends to provide incorrect identification, tracking, and forecasting in cases where there are dense cells whose shape changes rapidly or where clusters of storm cells occur frequently. Aiming to improve the performance of TITAN in such scenarios, an enhanced TITAN (ETITAN) algorithm is presented. The ETITAN algorithm provides enhancements to the original TITAN algorithm in three aspects. First, in order to handle the false merger problem when two storm cells are adjacent, and to isolate individual storm cells from a cluster of storms, ETITAN uses a multithreshold identification method based on mathematical morphology. Second, in the tracking phase, ETITAN proposes a dynamic constraint-based combinatorial optimization method to track storms. Finally, ETITAN uses the motion vector field calculated by the cross-correlation method to forecast the position of the individual isolated storm cells. Thus, ETITAN combines aspects of the two general classes of nowcasting algorithms, that is, cross-correlation and centroid-type methods, to improve nowcasting performance. Results of experiments presented in this paper show the performance improvements of the ETITAN algorithm.
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Charbonneau, Bianca, and Brenda Casper. "WIND TUNNEL TESTS OF HOW COASTAL PLANTS FEEDBACK ON DUNE SHAPE." Coastal Engineering Proceedings, no. 36 (December 30, 2018): 71. http://dx.doi.org/10.9753/icce.v36.sediment.71.
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Theoretical evolution of a coastal dune system starts at the individual plant level with the formation of bedforms, nebkha and shadow dunes, around plants. Over time, these initial bedforms can evolve into a fully developed foredune and eventually a complex dune system capable of buffering upland coastal areas against high tides and storms. Recent studies suggest that dunebuilding plant species may differ in their sand trapping efficiency and they may support different topographies, building dunes morphologically similar to their own stature – i.e. a taller steeper plant would build a taller and steeper dune. We believe that the bedforms created at the onset of dune evolution, i.e. after a storm or at the backbeach, may carry over through the life of the dune, such that understanding how plant morphology and density affects the initial formation stages of dune morphology is key to optimizing dune management, maintenance, and creation. With ERDC and USGS funding, we built a removable bed unilateral flow wind tunnel to test how the morphology among and within dominant US East coast foredune plants feeds back on bedform creation around individual plants at a baseline of zero (i.e. flat back beach or post storm).
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Klimenko, Maxim V., Vladimir V. Klimenko, Irina E. Zakharenkova, Konstantin G. Ratovsky, Nina A. Korenkova, Yury V. Yasyukevich, Anna A. Mylnikova, and Iurii V. Cherniak. "Similarity and differences in morphology and mechanisms of the <i>fo</i>F2 and TEC disturbances during the geomagnetic storms on 26–30 September 2011." Annales Geophysicae 35, no. 4 (August 9, 2017): 923–38. http://dx.doi.org/10.5194/angeo-35-923-2017.
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Abstract. This study presents an analysis of the ground-based observations and model simulations of ionospheric electron density disturbances at three longitudinal sectors (eastern European, Siberian and American) during geomagnetic storms that occurred on 26–30 September 2011. We use the Global Self-consistent Model of the Thermosphere, Ionosphere and Protonosphere (GSM TIP) to reveal the main mechanisms influencing the storm-time behavior of the total electron content (TEC) and the ionospheric F2 peak critical frequency (foF2) during different phases of geomagnetic storms. During the storm's main phase the long-lasting positive disturbances in TEC and foF2 at sunlit mid-latitudes are mainly explained by the storm-time equatorward neutral wind. The effects of eastward electric field can only explain the positive ionospheric storm in the first few hours of the initial storm phase. During the main phase the ionosphere was more changeable than the plasmasphere. The positive disturbances in the electron content at the plasmaspheric heights (800–20 000 km) at high latitudes can appear simultaneously with the negative disturbances in TEC and foF2. The daytime positive disturbances in foF2 and TEC occurred at middle and low latitudes and at the Equator due to n(O) ∕ n(N2) enhancement during later stage of the main phase and during the recovery phase of the geomagnetic storm. The plasma tube diffusional depletion and negative disturbances in electron and neutral temperature were the main formation mechanisms of the simultaneous formation of the positive disturbances in foF2 and negative disturbances in TEC at low latitudes during the storm's recovery phase.
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Romine, Glen S., Donald W. Burgess, and Robert B. Wilhelmson. "A Dual-Polarization-Radar-Based Assessment of the 8 May 2003 Oklahoma City Area Tornadic Supercell." Monthly Weather Review 136, no. 8 (August 1, 2008): 2849–70. http://dx.doi.org/10.1175/2008mwr2330.1.
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Abstract On 8 May 2003, a tornadic supercell tracked through portions of the Oklahoma City, Oklahoma, metropolitan area and produced violent damage along portions of its path. This storm passed through the dense in situ radar network in central Oklahoma and provided close-range operational, prototype polarimetric and terminal Doppler weather radar observations of the storm as it made the transition into the tornadic phase. The time-evolving polarimetric features were scrutinized with regard to storm morphology, particularly as related to the development of a rear-flank downdraft pulse within the storm immediately preceding the long-track tornado event. Two new polarimetric terms are introduced, the Zdr shield and Kdp foot, along with a discussion of the orientation of the Zdr and Kdp columns relative to midlevel rotation signatures. Storm downdraft and gust front characteristics are discussed relative to polarimetric fields and background environment characteristics. Highlighted for this event are a “warm” forward-flank downdraft and a particularly cold rear-flank downdraft. Emphasis is also placed on demonstrating key polarimetric field characteristics relative to traditional features at low and midlevels defined in familiar conceptual models of severe storms.
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Li, Honghai, Mitch Brown, Nicholas Kraus, Thomas Smith, and Jessica Podoski. "EVALUATION OF A PROPOSED CHANNEL ON CIRCULATION AND MORPHOLOGY CHANGE AT KAWAIHAE HARBOR AND PELEKANE BAY, HAWAII, USA." Coastal Engineering Proceedings 1, no. 32 (February 1, 2011): 79. http://dx.doi.org/10.9753/icce.v32.sediment.79.
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In an effort to improve the water quality and restore marine habitats in Pelekane Bay (PB), installation of a circulation channel was proposed with the intent of enhancing water circulation in PB through Kawaihae Deep Draft Harbor (KDDH) and flushing accumulated sediment out of PB. This study was conducted to investigate the hydraulics and sediment transport consequences of dredging such a channel. The coupled wave, flow, and sediment transport Coastal Modeling System (CMS) was applied during a non-storm and a typical winter (storms) time interval. CMS results were analyzed and compared between existing condition and channel alternatives. It was found that upon reaching PB, incident waves breaking induces higher water level from wave setup, whereas the breakwater at KDDH inhibits depth-limited breaking and setup, creating a differential in water surface elevation (WSE). The water level rise along the channel was calculated to be 0.01-0.03 m, with WSE in PB being higher. The differential wave setup, found for almost all wave conditions, produces water flow from PB to KDDH in the proposed channel. The temporally averaged along-channel current speed is calculated from 0.07 to 0.2 m/sec for the non-storm and storm conditions, respectively. Bay-to-harbor flows will move sediment into the channel, most of which is deposited within 120 m from PB. For the winter storm conditions, the maximum deposition in the channel was calculated to be approximately between 0.7 and 2.0 m among the different alternatives. More sand is deposited under the deeper channel alternatives. The channel or bay blockage appears under all channel alternatives before reaching the end of the simulation.
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Ma, Q., Y. Liu, C. Liu, J. Ma, and H. He. "A comprehensive characterisation of Asian dust storm particles: chemical composition, reactivity to SO<sub>2</sub>, and hygroscopic property." Atmospheric Chemistry and Physics Discussions 10, no. 4 (April 7, 2010): 8899–925. http://dx.doi.org/10.5194/acpd-10-8899-2010.
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Abstract. Mineral dust comprises of a significant fraction of the globe's aerosol loading. Yet it remains the largest uncertainty in future climate predictions due to the complexity in its components and physico-chemical properties. Multi-analysis methods, including SEM-EDX, FTIR, BET, TPD/mass, and Knudsen cell/mass, were used in the present study to characterise Asian dust storm particles. The morphology, element fraction, source distribution, true uptake coefficient of SO2 and hygroscopic behaviour were studied. The major components of Asian dust storm particles were found to consist of aluminosilicate, SiO2, and CaCO3, which were coated with organic compounds and inorganic nitrate. The dust storm particles have a low reactivity to SO2 (true uptake coefficient of 5.767×10−6) which limits the conversion of SO2 to sulfate during a dust storm period. The low reactivity also demonstrated that the heterogeneous reaction of SO2, in both dry and humid air conditions, had little effect on the hygroscopic behaviour of the dust particles. These results indicate that the impact of dust storms on atmospheric SO2 removal should not be overestimated.
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Mendillo, M., and C. Narvaez. "Ionospheric storms at geophysically-equivalent sites – Part 2: Local time storm patterns for sub-auroral ionospheres." Annales Geophysicae 28, no. 7 (July 15, 2010): 1449–62. http://dx.doi.org/10.5194/angeo-28-1449-2010.
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Abstract. The response of the mid-latitude ionosphere to geomagnetic storms depends upon several pre-storm conditions, the dominant ones being season and local time of the storm commencement (SC). The difference between a site's geographic and geomagnetic latitudes is also of major importance since it governs the blend of processes linked to solar production and magnetospheric input, respectively. Case studies of specific storms using ionospheric data from both hemispheres are inherently dominated by seasonal effects and the various local times versus longitude of the SCs. To explore inter-hemispheric consistency of ionospheric storms, we identify "geophysically-equivalent-sites" as locations where the geographic and geomagnetic latitudes have the same relationship to each other in both hemispheres. At the longitudes of the dipole tilt, the differences between geographic and geomagnetic latitudes are at their extremes, and thus these are optimal locations to see if pre-conditioning and/or storm-time input are the same or differ between the hemispheres. In this study, we use ionosonde values of the F2-layer maximum electron density (NmF2) to study geophysical equivalency at Wallops Island (VA) and Hobart (Tasmania), using statistical summaries of 206 events during solar cycle #20. We form average patterns of ΔNmF2 (%) versus local time over 7-day storm periods that are constructed in ways that enhance the portrayal of the average characteristic features of the positive and negative phases of ionospheric storms. The results show a consistency between four local time characteristic patterns of storm-induced perturbations, and thus for the average magnitudes and time scales of the processes that cause them in each hemisphere. Subtle differences linked to small departures from pure geophysical equivalency point to a possible presence of hemispheric asymmetries governed by the non-mirror-image of geomagnetic morphology in each hemisphere.
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Cander, Ljiljana R. "Mid-Latitude Single Station F region Storm Morphology and Forecast." Acta Geophysica 64, no. 2 (April 2016): 541–66. http://dx.doi.org/10.1515/acgeo-2016-0007.
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Morales-Márquez, Verónica, Alejandro Orfila, Gonzalo Simarro, Lluís Gómez-Pujol, Amaya Álvarez-Ellacuría, Daniel Conti, Álvaro Galán, Andrés F. Osorio, and Marta Marcos. "Numerical and remote techniques for operational beach management under storm group forcing." Natural Hazards and Earth System Sciences 18, no. 12 (December 3, 2018): 3211–23. http://dx.doi.org/10.5194/nhess-18-3211-2018.
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Abstract. The morphodynamic response of a microtidal beach under a storm group is analyzed, and the effects of each individual event are inferred from a numerical model, in situ measurements and video imaging. The combination of these approaches represents a multiplatform tool for beach management, especially during adverse conditions. Here, the morphodynamic response is examined during a period with a group of three storms. The first storm, with moderate conditions (Hs∼1 m during 6 h), eroded the aerial beach and generated a submerged sandbar in the breaking zone. The bar was further directed offshore during the more energetic second event (Hs=3.5 m and 53 h). The third storm, similar to the first one, hardly affected the beach morphology, which stresses the importance of the beach configuration previous to a storm. The volume of sand mobilized during the storm group is around 17.65 m3 m−1. During the following months, which are characterized by mild wave conditions, the aerial beach recovered half of the volume of sand that is transported offshore during the storm group (∼9.27m3m-1). The analysis of beach evolution shows two different characteristic timescales for the erosion and recovery processes associated with the storm and mild conditions, respectively. In addition, the response depends largely on the previous beach morphological state. The work also stresses the importance of using different tools (video monitoring, modeling, and field campaign) to analyze beach morphodynamics.
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Oliver, Thomas S. N., and Toru Tamura. "Sub-centennially resolved behavior of an accreting sandy shoreline over the past ∼ 1000 years." Journal of Sedimentary Research 91, no. 2 (February 28, 2021): 211–18. http://dx.doi.org/10.2110/jsr.2020.074.
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ABSTRACT Coastal ridge plains represent a valuable record of past shoreline deposition. However, there remain questions regarding shoreline behavior on intermediate timescales (sub-centennial), the impact of storms, and process of ridge genesis. We address these questions through high-resolution reconstruction of the sandy-beach progradation at Boydtown Beach in Twofold Bay, southeastern Australia, over the past 1000 years using ground-penetrating radar (GPR) and optically stimulated luminescence (OSL) dating. GPR profiles are dominated by seaward-dipping reflections that result from beach and dune progradation. Prominent reflections with heavy-mineral concentrations are also preserved resulting from storm erosion. OSL ages reveal alternative phases of steady and episodic accretion, rather than a constant progradation. We hypothesize that steady phases may result from moderate storm events where each successive storm only partially erodes the recovery of the previous event. This results in incremental seaward accretion of the active beach. Phases of episodic accretion could be the result of larger storm events or storm clusters when large post-storm recovery rapidly shifts the active shoreline seaward. The two modes of shoreline progradation (steady and episodic) appear broadly associated with a change in ridge-and-swale morphology whereby subdued ridge swale topography is associated with steady or incremental progradation and higher, better-defined ridges with episodic accretion. These results suggest that a single coastal ridge plain experiences variable intermediate-scale shoreline behavior in response to storm events which then lead to multiple modes of ridge genesis.
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Grases, Albert, Vicente Gracia, Manuel García-León, Jue Lin-Ye, and Joan Pau Sierra. "Coastal Flooding and Erosion under a Changing Climate: Implications at a Low-Lying Coast (Ebro Delta)." Water 12, no. 2 (January 25, 2020): 346. http://dx.doi.org/10.3390/w12020346.
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Episodic coastal hazards associated to sea storms are responsible for sudden and intense changes in coastal morphology. Climate change and local anthropogenic activities such as river regulation and urban growth are raising risk levels in coastal hotspots, like low-lying areas of river deltas. This urges to revise present management strategies to guarantee their future sustainability, demanding a detailed diagnostic of the hazard evolution. In this paper, flooding and erosion under current and future conditions have been assessed at local scale at the urban area of Riumar, a touristic enclave placed at the Ebro Delta (Spain). Process-based models have been used to address the interaction between beach morphology and storm waves, as well as the influence of coastal environment complexity. Storm waves have been propagated with SWAN wave model and have provided the forcings for XBeach, a 2DH hydro-morphodynamic model. Results show that future trends in sea level rise and wave forcing produce non-linear variations of the flooded area and the volume of mobilized sediment resulting from marine storms. In particular, the balance between flooding and sediment transport will shift depending on the relative sea level. Wave induced flooding and long-shore sand transport seem to be diminished in the future, whereas static sea level flooding and cross-shore sediment transport are exacerbated. Therefore, the characterization of tipping points in the coastal response can help to develop robust and adaptive plans to manage climate change impact in sandy wave dominated coasts with a low-lying hinterland and a complex shoreline morphology.
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Potvin, Corey K., Patrick S. Skinner, Kimberly A. Hoogewind, Michael C. Coniglio, Jeremy A. Gibbs, Adam J. Clark, Montgomery L. Flora, Anthony E. Reinhart, Jacob R. Carley, and Elizabeth N. Smith. "Assessing Systematic Impacts of PBL Schemes on Storm Evolution in the NOAA Warn-on-Forecast System." Monthly Weather Review 148, no. 6 (May 27, 2020): 2567–90. http://dx.doi.org/10.1175/mwr-d-19-0389.1.
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Abstract The NOAA Warn-on-Forecast System (WoFS) is an experimental rapidly updating convection-allowing ensemble designed to provide probabilistic operational guidance on high-impact thunderstorm hazards. The current WoFS uses physics diversity to help maintain ensemble spread. We assess the systematic impacts of the three WoFS PBL schemes—YSU, MYJ, and MYNN—using novel, object-based methods tailored to thunderstorms. Very short forecast lead times of 0–3 h are examined, which limits phase errors and thereby facilitates comparisons of observed and model storms that occurred in the same area at the same time. This evaluation framework facilitates assessment of systematic PBL scheme impacts on storms and storm environments. Forecasts using all three PBL schemes exhibit overly narrow ranges of surface temperature, dewpoint, and wind speed. The surface biases do not generally decrease at later forecast initialization times, indicating that systematic PBL scheme errors are not well mitigated by data assimilation. The YSU scheme exhibits the least bias of the three in surface temperature and moisture and in many sounding-derived convective variables. Interscheme environmental differences are similar both near and far from storms and qualitatively resemble the differences analyzed in previous studies. The YSU environments exhibit stronger mixing, as expected of nonlocal PBL schemes; are slightly less favorable for storm intensification; and produce correspondingly weaker storms than the MYJ and MYNN environments. On the other hand, systematic interscheme differences in storm morphology and storm location forecast skill are negligible. Overall, the results suggest that calibrating forecasts to correct for systematic differences between PBL schemes may modestly improve WoFS and other convection-allowing ensemble guidance at short lead times.
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Lee, Bruce D., Brian F. Jewett, and Robert B. Wilhelmson. "The 19 April 1996 Illinois Tornado Outbreak. Part I: Cell Evolution and Supercell Isolation." Weather and Forecasting 21, no. 4 (August 1, 2006): 433–48. http://dx.doi.org/10.1175/waf944.1.
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Abstract In this study of the 19 April 1996 Illinois tornado outbreak, 109 cells were tracked using radar data to understand the transition of the cell configuration from a considerable number of initial cells to a small subset of supercells after several hours of evolution. Of these 109 cells, 85 developed along three synoptic boundaries (dryline, warm front, and dryline–warm front occlusion) between 1940 and 2230 UTC. A large majority of these 85 cells formed in a 1-h period between 2040 and 2140 UTC. With a considerable number of cells initiating within a short time period, the early stages of cell organization were marked by cell merger interactions and cell attrition that led to a pattern of isolated tornadic supercells. Cell-type initiation analysis revealed that storms that would become supercells were initiated, on average, 17 min before nonsupercell storms. Cyclonic supercells, with mean storm life spans of 214 min, had much longer lives than nonsupercell storms. Anticyclonic supercells resulting from storm splits were the second longest lived at 166 min. In comparison, the largest nonsupercell category, those cells that dissipated in relative isolation, only had 35-min life spans. Supercell isolation resulted from storm mergers due to differential cell propagation and the frequent attrition of cells that formed along a common boundary. The varying rotational properties of individual cells enhanced the probability for numerous mergers while fostering a scenario where, after a few hours, the supercells became increasingly isolated. Suggestions are presented to raise the awareness level of forecasters to key aspects of cell evolution and interaction in nowcasting severe convection. In Part II of this study, storm interactions are examined in the context of merger morphology, merged cell intensity changes, and the association between storm mergers and tornadogenesis.
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Mikhailov, A. V., and K. Schlegel. "Geomagnetic storm effects at F1-layer heights from incoherent scatter observations." Annales Geophysicae 21, no. 2 (February 28, 2003): 583–96. http://dx.doi.org/10.5194/angeo-21-583-2003.
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Abstract. Storm effects at F1-layer heights (160–200 km) were analyzed for the first time using Millstone Hill (mid-latitudes) and EISCAT (auroral zone) incoherent scatter (IS) observations. The morphological study has shown both increases (positive effect) and decreases (negative effect) in electron concentration. Negative storm effects prevail for all seasons and show a larger magnitude than positive ones, the magnitude of the effect normally increasing with height. At Millstone Hill the summer storm effects are small compared to other seasons, but they are well detectable. At EISCAT this summer decrease takes place only with respect to the autumnal period and the autumn/spring asymmetry in the storm effects is well pronounced. Direct and significant correlation exists between deviations in electron concentration at the F1-layer heights and in the F2-layer maximum. Unlike the F2-layer the F1-region demonstrates a relatively small reaction to geomagnetic disturbances despite large perturbations in thermospheric parameters. Aeronomic parameters extracted from IS observations are used to explain the revealed morphology. A competition between atomic and molecular ion contributions to Ne variations was found to be the main physical mechanism controlling the F1-layer storm effect. The revealed morphology is shown to be related with neutral composition (O, O2, N2) seasonal and storm-time variations. The present day understanding of the F1-region formation mechanisms is sufficient to explain the observed storm effects.Key words. Atmospheric composition and structure (thermosphere-composition and chemistry); ionosphere (ion chemistry and composition; ionospheric disturbances)
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Ashley, Sharon T., and Walker S. Ashley. "The storm morphology of deadly flooding events in the United States." International Journal of Climatology 28, no. 4 (2008): 493–503. http://dx.doi.org/10.1002/joc.1554.
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Adeniyi, J. O. "Magnetic storm effects on the morphology of the equatorial F2-layer." Journal of Atmospheric and Terrestrial Physics 48, no. 8 (August 1986): 695–702. http://dx.doi.org/10.1016/0021-9169(86)90019-x.
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Medellín, Gabriela, Martí Mayor, Christian M. Appendini, Ruth Cerezo-Mota, and José A. Jiménez. "The Role of Beach Morphology and Mid-Century Climate Change Effects on Wave Runup and Storm Impact on the Northern Yucatan Coast." Journal of Marine Science and Engineering 9, no. 5 (May 11, 2021): 518. http://dx.doi.org/10.3390/jmse9050518.
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Wave runup is a relevant parameter to determine the storm impact on barrier islands. Here, the role of the beach morphology on wave runup and storm impact was investigated at four coastal communities located on the northern Yucatan coast. Current wave conditions based on regional wind simulations, topo-bathymetric transects measured at each location, and a nonlinear wave transformation model were employed to reconstruct multi-year runup time series. Dune morphology features and extreme water levels (excluding storm surge contributions) were further employed to determine the storm impact at each site for different return periods. Despite the similar offshore conditions along the coast, extreme water levels (i.e., runup and setup) showed intersite differences that were mainly ascribed to subaerial and submerged morphological features. Numerical results showed that the average surf zone beach slope, sandbars, berm, and dune elevation played an important role in controlling extreme water levels and storm impact at the study sites under the present climate. Moreover, in order to assess the potential effect of climate change on coastal flooding, we analyzed wave runup and storm impact in the best-preserved site by considering wave conditions and sea level rise (SLR) projections under the RCP 8.5 scenario. Modelling results suggest no significant increase in the storm impact regime between the present and future conditions in the study area unless SLR is considered. It was found that to accurately estimate SLR contribution, it should be incorporated into mean sea level prior to performing numerical wave runup simulations, rather than simply adding it to the resulting wave-induced water levels.
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Gagne, David John, Amy McGovern, and Jerry Brotzge. "Classification of Convective Areas Using Decision Trees." Journal of Atmospheric and Oceanic Technology 26, no. 7 (July 1, 2009): 1341–53. http://dx.doi.org/10.1175/2008jtecha1205.1.
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Abstract This paper presents an automated approach for classifying storm type from weather radar reflectivity using decision trees. Recent research indicates a strong relationship between storm type (morphology) and severe weather, and such information can aid in the warning process. Furthermore, new adaptive sensing tools, such as the Center for Collaborative Adaptive Sensing of the Atmosphere’s (CASA’s) weather radar, can make use of storm-type information in real time. Given the volume of weather radar data from those tools, manual classification of storms is not possible when dealing with real-time data streams. An automated system can more quickly and efficiently sort through real-time data streams and return value-added output in a form that can be more easily manipulated and understood. The method of storm classification in this paper combines two machine learning techniques: K-means clustering and decision trees. K-means segments the reflectivity data into clusters, and decision trees classify each cluster. The K means was used to separate isolated cells from linear systems. Each cell received labels such as “isolated pulse,” “isolated strong,” or “multicellular.” Linear systems were labeled as “trailing stratiform,” “leading stratiform,” and “parallel stratiform.” The classification scheme was tested using both simulated and observed storms. The simulated training and test datasets came from the Advanced Regional Prediction System (ARPS) simulated reflectivity data, and observed data were collected from composite reflectivity mosaics from the CASA Integrative Project One (IP1) network. The observations from the CASA network showed that the classification scheme is now ready for operational use.
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Alfaro, Diego A., and Marat Khairoutdinov. "Thermodynamic Constraints on the Morphology of Simulated Midlatitude Squall Lines." Journal of the Atmospheric Sciences 72, no. 8 (August 1, 2015): 3116–37. http://dx.doi.org/10.1175/jas-d-14-0295.1.
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Abstract This study examines how environmental thermodynamics constrain the morphology of simulated idealized midlatitude squall lines (SLs). The thermodynamic soundings used for simulating various SLs are specified primarily by prescribed vertical profiles of the convective available potential energy (CAPE) and the level of free convection. This framework, which contemplates the latent instability properties of both low- and midtropospheric air, is considered to be convenient for investigating layer-lifting convective phenomena. Results show that frequently used CAPE indices are unsuitable for diagnosing SL characteristics, while integrated CAPE (ICAPE) discriminates the amplitude of the storm-induced heating for a given value of environmental shear. The skill of ICAPE follows from its relation to the buoyancy attained by low- and midtropospheric parcels as they ascend over the cold pool under layer-lifting convection. Environmental kinematics also affect the storm-induced heating, with stronger low-level shear leading to a greater proportion of inflowing latent unstable air among total storm-relative inflow, thus producing higher temperatures aloft. The precipitable water accounts for much of the precipitation-rate variation for a given value of shear. The precipitation efficiency is lower in environments with weaker shear and dryer midtropospheric conditions. Cold pool temperatures are slightly affected by environmental variations beneath the layer of minimum moist static energy, with drier midtropospheric conditions and weaker shear leading to warmer cold pools. SLs with a small vertical gradient of cold pool buoyancy propagate less rapidly and produce small surface wind speeds. Cold pool properties could be affected by a descending branch of the front-to-rear flow, which crosses over with the rear inflow jet.
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Montreuil, A. L., M. Chen, A. Esquerré, R. Houthuys, R. Moelans, and P. Bogaert. "PRE- and POST-STORM LiDAR SURVEYS FOR ASSESSMENT OF IMPACT ON COASTAL EROSION." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-3/W8 (August 21, 2019): 261–66. http://dx.doi.org/10.5194/isprs-archives-xlii-3-w8-261-2019.
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<p><strong>Abstract.</strong> Sustainable management of the coastal resources requires a better understanding of the processes that drive coastline change. The coastline is a highly dynamic sea-terrestrial interface. It is affected by forcing factors such as water levels, waves, winds, and the highest and most severe changes occur during storm surges. Extreme storms are drivers responsible for rapid and sometimes dramatic changes of the coastline. The consequences of the impacts from these events entail a broad range of social, economic and natural resource considerations from threats to humans, infrastructure and habitats. This study investigates the impact of a severe storm on coastline response on a sandy multi-barred beach at the Belgian coast. Airborne LiDAR surveys acquired pre- and post-storm covering an area larger than 1 km<sup>2</sup> were analyzed and reproducible monitoring solutions adapted to assess beach morphological changes were applied. Results indicated that the coast retreated by a maximum of 14.7 m where the embryo dunes in front of the fixed dunes were vanished and the foredune undercut. Storm surge and wave attacks were probably the most energetic there. However, the response of the coastline proxies associated with the mean high water line (MHW) and dunetoe (DuneT) was spatially variable. Based on the extracted beach features, good correlations (r>0.73) were found between coastline, berm and inner intertidal bar morphology, while it was weak with the most seaward bars covered in the surveys. This highlights the role of the upper features on the beach to protect the coastline from storm erosion by reducing wave energy. The findings are of critical importance in improving our knowledge and forecasting of coastline response to storms, and also in its translation into management practices.</p>
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Golladay, S. W., J. R. Webster, and E. F. Benfield. "Changes in Stream Morphology and Storm Transport of Seston Following Watershed Disturbance." Journal of the North American Benthological Society 6, no. 1 (March 1987): 1–11. http://dx.doi.org/10.2307/1467519.
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Shariful, Fatihah, Mouncef Sedrati, Effi Helmy Ariffin, Syazana Md Shubri, and Mohd Fadzil Akhir. "Impact of 2019 Tropical Storm (Pabuk) on Beach Morphology, Terengganu Coast (Malaysia)." Journal of Coastal Research 95, sp1 (May 26, 2020): 346. http://dx.doi.org/10.2112/si95-067.1.
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Houser, Chris. "Alongshore variation in the morphology of coastal dunes: Implications for storm response." Geomorphology 199 (October 2013): 48–61. http://dx.doi.org/10.1016/j.geomorph.2012.10.035.
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Catto, Norm R. "More than 16 Years, More than 16 Stressors: Evolution of a Reflective Gravel Beach, 1989-2005." Géographie physique et Quaternaire 60, no. 1 (September 19, 2007): 49–62. http://dx.doi.org/10.7202/016364ar.
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Abstract Mobile Beach, a reflective, moderate-to-high energy, gravel bayhead bar system in eastern Newfoundland, has been influenced by 15 hurricanes and strong winter storms, and at least 9 significant autumn and winter storms between July 1989 and December 2005. Yearly variations in the extent of seasonal ice cover offshore, and snow cover, ice foot development, and freezing of beach sediment, also have shaped Mobile Beach. Vehicle activity and foot traffic have resulted in coarsening, compaction, and steepening. Excavation of a drainage channel through the beach affected sediment supply and transport. Changes in hurricane activity, in the occurrence and impact of northeast winds, and in seasonal ice cover, play a major role in shaping coastal morphology, in conjunction with sea level rise. Variations in the North Atlantic Oscillation are reflected in storm effectiveness and snow and ice influence. Tropical storm and hurricane activity results in substantial modifications to the beach, but the erosional events cannot be correlated with overall variations in hurricane activity. Although Mobile Beach does respond to large-scale regional to hemispheric factors, local factors, including the angle of wave attack, the number of previous events, and anthropogenic activity, play the dominant role here.
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Li, Xiaofeng, Jun A. Zhang, Xiaofeng Yang, William G. Pichel, Mark DeMaria, David Long, and Ziwei Li. "Tropical Cyclone Morphology from Spaceborne Synthetic Aperture Radar." Bulletin of the American Meteorological Society 94, no. 2 (February 1, 2013): 215–30. http://dx.doi.org/10.1175/bams-d-11-00211.1.
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In 2008, the Canadian Space Agency sponsored the Radarsat Hurricane Applications Project (RHAP), for researching new developments in the application of Radarsat-1 synthetic aperture radar (SAR) data and innovative mapping approaches to better understand the dynamics of tropical cyclone genesis, morphology, and movement. Although tropical cyclones can be detected by many remote sensors, SAR can yield high-resolution (subkilometer) and low-level storm information that cannot be seen below the clouds by other sensors. In addition to the wind field and tropical cyclone eye information, structures associated with atmospheric processes can also be detected by SAR. We have acquired 161 Radarsat-1 SAR images through RHAP between 2001 and 2007. Among these, 73 images show clear tropical cyclone eye structure. In addition, we also acquired 10 images from the European Space Agency's Envisat SAR between 2004 and 2010. Both Atlantic hurricanes and Pacific typhoons are included. In this study, we analyze these 83 (73 Radarsat-1 and 10 Envisat) images with tropical cyclone eye information along with ancillary tropical cyclone intensity information from the archive to generate tropical cyclone morphology statistics. Histograms of wave-number asymmetry and intensity are presented. The statistics show that when the storm has higher intensity, the tropical cyclone eye tends to become more symmetric, and the area of the tropical cyclone eye, defined by the minimum wind area, tends to be smaller. Examples of finescale structures within the tropical cyclone (i.e., eye/eyewall mesovortices, arc clouds, double eyewalls, and abnormally high wind or rain within eyes) are presented and discussed.
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Gagne II, David John, Sue Ellen Haupt, Douglas W. Nychka, and Gregory Thompson. "Interpretable Deep Learning for Spatial Analysis of Severe Hailstorms." Monthly Weather Review 147, no. 8 (July 17, 2019): 2827–45. http://dx.doi.org/10.1175/mwr-d-18-0316.1.
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Abstract Deep learning models, such as convolutional neural networks, utilize multiple specialized layers to encode spatial patterns at different scales. In this study, deep learning models are compared with standard machine learning approaches on the task of predicting the probability of severe hail based on upper-air dynamic and thermodynamic fields from a convection-allowing numerical weather prediction model. The data for this study come from patches surrounding storms identified in NCAR convection-allowing ensemble runs from 3 May to 3 June 2016. The machine learning models are trained to predict whether the simulated surface hail size from the Thompson hail size diagnostic exceeds 25 mm over the hour following storm detection. A convolutional neural network is compared with logistic regressions using input variables derived from either the spatial means of each field or principal component analysis. The convolutional neural network statistically significantly outperforms all other methods in terms of Brier skill score and area under the receiver operator characteristic curve. Interpretation of the convolutional neural network through feature importance and feature optimization reveals that the network synthesized information about the environment and storm morphology that is consistent with our understanding of hail growth, including large lapse rates and a wind shear profile that favors wide updrafts. Different neurons in the network also record different storm modes, and the magnitude of the output of those neurons is used to analyze the spatiotemporal distributions of different storm modes in the NCAR ensemble.
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Flournoy, Matthew D., Michael C. Coniglio, and Erik N. Rasmussen. "Examining Relationships between Environmental Conditions and Supercell Motion in Time." Weather and Forecasting 36, no. 3 (June 2021): 737–55. http://dx.doi.org/10.1175/waf-d-20-0192.1.
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AbstractAlthough environmental controls on bulk supercell potential and hazards have been studied extensively, relationships between environmental conditions and temporal changes to storm morphology remain less explored. These relationships are examined in this study using a compilation of sounding data collected during field campaigns from 1994 to 2019 in the vicinity of 216 supercells. Environmental parameters are calculated from the soundings and related to storm-track characteristics like initial cell motion and the time of the right turn (i.e., the time elapsed between the cell initiation and the first time when the supercell obtains a quasi-steady motion that is directed clockwise from its initial motion.). We do not find any significant associations between environmental parameters and the time of the right turn. Somewhat surprisingly, no relationship is found between storm-relative environmental helicity and the time elapsed between cell initiation and the onset of deviant motion. Initial cell motion is best approximated by the direction of the 0–6-km mean wind at two-thirds the speed. This is a result of advection and propagation in the 0–4- and 0–2-km layers, respectively. Unsurprisingly, Bunkers-right storm motion is a good estimate of post-turn motion, but storms that exhibit a post-turn motion left of Bunkers-right are less likely to be tornadic. These findings are relevant for real-time forecasting efforts in predicting the path and tornado potential of supercells up to hours in advance.
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Li, Jie, Longyi Shao, Lingli Chang, Jiaoping Xing, Wenhua Wang, Wenjun Li, and Daizhou Zhang. "Physicochemical Characteristics and Possible Sources of Individual Mineral Particles in a Dust Storm Episode in Beijing, China." Atmosphere 9, no. 7 (July 16, 2018): 269. http://dx.doi.org/10.3390/atmos9070269.
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Beijing frequently experiences dust storms during spring, which result in deteriorated visibility and cause negative health impacts. In this paper, the dust particles were collected during a dust storm episode on 4–5 May 2017 in Beijing, and the samples before and after the dust storm were also collected. The morphology and elemental and mineralogical compositions of the dust samples were investigated using a transmission electron microscope equipped with an energy-dispersive X-ray spectrometer (TEM-EDX) and X-ray diffraction (XRD). The TEM-EDX results showed that the particles in the dust samples were mainly Si-rich, Ca-rich, S-rich, Fe-rich, Al-rich, Ti-rich, K-rich, Na-rich and Mg-rich particles. The XRD results demonstrated that the minerals in PM10 samples were mainly clay, calcite, quartz, dolomite, plagioclase, potassium feldspar and hematite, in descending order of their contents. The clay minerals, having the highest content, were mainly kaolinite, chlorite and illite. The mixing state and aging degree of mineral particles before, during and after the dust storm episode behaved very differently. The mineral particles collected before and after the dust storm tended to have an internal mixing state, dominated by the S-rich particles internally mixed with alkaline mineral particles, revealing a more serious ageing degree. The mineral particles collected during the dust storm did not show clear internal mixing, revealing a less serious ageing degree. The amount of the Si-rich, Al-rich, Ca-rich and Ti-rich particles was highest during the dust storm, indicating that these particles mainly originated from long-distance transportation. The S-rich, Fe-rich, K-rich, Na-rich and Mg-rich particles were mainly enriched in the samples before and after the dust storm episode, indicating that they mainly originated from local sources. A comparison of the values of S/(Si + Al) in the individual particles with the particle sizes revealed that the finer mineral particles were associated with higher S contents before and after the dust storm, while the coarse particles were associated with lower S contents during the dust storm.
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Nowotarski, Christopher J., Paul M. Markowski, Yvette P. Richardson, and George H. Bryan. "Supercell Low-Level Mesocyclones in Simulations with a Sheared Convective Boundary Layer." Monthly Weather Review 143, no. 1 (January 1, 2015): 272–97. http://dx.doi.org/10.1175/mwr-d-14-00151.1.
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Abstract Simulations of supercell thunderstorms in a sheared convective boundary layer (CBL), characterized by quasi-two-dimensional rolls, are compared with simulations having horizontally homogeneous environments. The effects of boundary layer convection on the general characteristics and the low-level mesocyclones of the simulated supercells are investigated for rolls oriented either perpendicular or parallel to storm motion, as well as with and without the effects of cloud shading. Bulk measures of storm strength are not greatly affected by the presence of rolls in the near-storm environment. Though boundary layer convection diminishes with time under the anvil shadow of the supercells when cloud shading is allowed, simulations without cloud shading suggest that rolls affect the morphology and evolution of supercell low-level mesocyclones. Initially, CBL vertical vorticity perturbations are enhanced along the supercell outflow boundary, resulting in nonnegligible near-ground vertical vorticity regardless of roll orientation. At later times, supercells that move perpendicular to the axes of rolls in their environment have low-level mesocyclones with weaker, less persistent circulation compared to those in a similar horizontally homogeneous environment. For storms moving parallel to rolls, the opposite result is found: that is, low-level mesocyclone circulation is often enhanced relative to that in the corresponding horizontally homogeneous environment.
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Schumann, Melissa R., and Paul J. Roebber. "The Influence of Upper-Tropospheric Potential Vorticity on Convective Morphology." Monthly Weather Review 138, no. 2 (February 1, 2010): 463–74. http://dx.doi.org/10.1175/2009mwr3091.1.
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Abstract Extensive research has illuminated the roles that buoyancy and vertical wind shear have in determining convective mode. The goal of this study is to examine synoptic forcing, as measured by the form of the waves on the dynamic tropopause and the strength of the resultant temperature advection, together with the environmental variables that are currently used to differentiate storm type. Logistic regression is used to make this discrimination and provides the preliminary results. First, multicellular lines and isolated rotating cells are associated with weaker synoptic forcing. Second, where an upper-level feature is present, multicellular convection (lines and clusters combined) is favored relative to isolated storms when there is stronger synoptic forcing, the shape of the upper-level potential vorticity (PV) feature is elongated, and there is a more southerly component in the deep-layer (0–6 km) mean wind. Third, when an upper-level feature is present and the convection is multicellular, clusters are favored relative to lines when the upper wave is not cut off (i.e., a wave structure promoting advection), provided that the deep-layer shear is not oriented at an optimal angle relative to a preexisting meridional boundary (as shown by prior research). Finally, if the convection is isolated, rotating storms may be favored for a broad area of PV advection, as measured by the relative equality of the zonal and meridional axes of the advection area, suggesting the importance of broader-scale destabilization. These findings are used to formulate testable hypotheses. Future model-based experiments using PV surgery or PV regression methods are proposed to clearly elucidate the dynamics behind these relationships.
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Zoccatelli, D., M. Borga, A. Viglione, G. B. Chirico, and G. Blöschl. "Spatial moments of catchment rainfall: rainfall spatial organisation, basin morphology, and flood response." Hydrology and Earth System Sciences 15, no. 12 (December 20, 2011): 3767–83. http://dx.doi.org/10.5194/hess-15-3767-2011.
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Abstract. This paper describes a set of spatial rainfall statistics (termed "spatial moments of catchment rainfall") quantifying the dependence existing between spatial rainfall organisation, basin morphology and runoff response. These statistics describe the spatial rainfall organisation in terms of concentration and dispersion statistics as a function of the distance measured along the flow routing coordinate. The introduction of these statistics permits derivation of a simple relationship for the quantification of catchment-scale storm velocity. The concept of the catchment-scale storm velocity takes into account the role of relative catchment orientation and morphology with respect to storm motion and kinematics. The paper illustrates the derivation of the statistics from an analytical framework recently proposed in literature and explains the conceptual meaning of the statistics by applying them to five extreme flash floods occurred in various European regions in the period 2002–2007. High resolution radar rainfall fields and a distributed hydrologic model are employed to examine how effective are these statistics in describing the degree of spatial rainfall organisation which is important for runoff modelling. This is obtained by quantifying the effects of neglecting the spatial rainfall variability on flood modelling, with a focus on runoff timing. The size of the study catchments ranges between 36 to 982 km2. The analysis reported here shows that the spatial moments of catchment rainfall can be effectively employed to isolate and describe the features of rainfall spatial organization which have significant impact on runoff simulation. These statistics provide useful information on what space-time scales rainfall has to be monitored, given certain catchment and flood characteristics, and what are the effects of space-time aggregation on flood response modeling.
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Tyrlis, E., and B. J. Hoskins. "The Morphology of Northern Hemisphere Blocking." Journal of the Atmospheric Sciences 65, no. 5 (May 1, 2008): 1653–65. http://dx.doi.org/10.1175/2007jas2338.1.
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Abstract The morphology of regional blocking in the Northern Hemisphere is discussed using the 40-yr ECMWF Re-Analysis (ERA-40) dataset and a measure of blocking based on the reversal at storm-track latitudes of meridional θ contrasts on a potential vorticity (PV) surface representative of the tropopause. The focus is on cyclonic and anticyclonic Rossby wave breaking that is inherent to the blocking development, and the extent to which this is determined by the climatological jet position and the ambient shears. More generally, the importance of the climatological planetary scale is discussed. The approach is mainly through composite behavior, but informed by consideration of many individual events. A diversity of behavior is found with longitude in both winter and summer, and there is a striking reversal of the sense of the wave breaking between the two seasons that is generally consistent with the difference in the jet locations. Preferred behaviors are found in various regions and seasons, and retrogression of blocking is discussed.
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Miller, Steven D., William C. Straka, Jia Yue, Curtis J. Seaman, Shuang Xu, Christopher D. Elvidge, Lars Hoffmann, and Irfan Azeem. "The Dark Side of Hurricane Matthew: Unique Perspectives from the VIIRS Day/Night Band." Bulletin of the American Meteorological Society 99, no. 12 (December 2018): 2561–74. http://dx.doi.org/10.1175/bams-d-17-0097.1.
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AbstractHurricane Matthew (28 September–9 October 2016) was perhaps the most infamous storm of the 2016 Atlantic hurricane season, claiming over 600 lives and causing over $15 billion (U.S. dollars) in damages across the central Caribbean and southeastern U.S. seaboard. Research surrounding Matthew and its many noteworthy meteorological characteristics (e.g., rapid intensification into the southernmost category 5 hurricane in the Atlantic basin on record, strong lightning and sprite production, and unusual cloud morphology) is ongoing. Satellite remote sensing typically plays an important role in the forecasting and study of hurricanes, providing a top-down perspective on storms developing over the remote and inherently data-sparse tropical oceans. In this regard, a relative newcomer among the suite of satellite observations useful for tropical cyclone monitoring and research is the Visible Infrared Imaging Radiometer Suite (VIIRS) day/night band (DNB), a sensor flying on board the NOAA–NASA Suomi National Polar-Orbiting Partnership (SNPP) satellite. Unlike conventional instruments, the DNB’s sensitivity to extremely low levels of visible and near-infrared light offers new insight into storm properties and impacts. Here, we chronicle Matthew’s path of destruction and peer through the DNB’s looking glass of low-light visible observations, including lightning connected to sprite formation, modulation of the atmospheric nightglow by storm-generated gravity waves, and widespread power outages. Collected without moonlight, these examples showcase the wealth of unique information present in DNB nocturnal low-light observations without moonlight, and their potential to complement traditional satellite measurements of tropical storms worldwide.
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Mikhailov, A. V., A. H. Depueva, and V. H. Depuev. "Daytime F2-layer negative storm effect: what is the difference between storm-induced and Q-disturbance events?" Annales Geophysicae 25, no. 7 (July 30, 2007): 1531–41. http://dx.doi.org/10.5194/angeo-25-1531-2007.
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Abstract. Negative F2-layer storms related to geomagnetic activity and quiet-time disturbances (Q-disturbances) belong to different classes of events and exhibit different morphology. Mid-latitude daytime Q-disturbances, unlike the usual negative F2-layer storms, demonstrate NmF2 and hmF2 in-phase variations. An analysis of Millstone Hill ISR observations for usual and Q-disturbances has shown the difference in the controlling aeronomic parameter variations for the two classes of events. The decrease in atomic oxygen concentration provides the main contribution to the hmF2 decrease below the monthly median level during Q-disturbance events. Unlike the usual negative storms, the negative effect takes place in the whole topside ionosphere under Q-disturbance conditions. The difference is due to different effective plasma scale heights in the two cases. Clustering of the usual negative F2-layer disturbances around equinoxes and Q-disturbances around winter solstice, as well as different latitudinal variations for the occurrence of the two types of disturbances is due to their different formation mechanisms.