Добірка наукової літератури з теми "Synoptic anomalies"

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Статті в журналах з теми "Synoptic anomalies":

1

Nastos, P. T., and I. T. Matsangouras. "Analysis of synoptic conditions for tornadic days over Western Greece." Natural Hazards and Earth System Sciences Discussions 2, no. 3 (March 2014): 2215–43. http://dx.doi.org/10.5194/nhessd-2-2215-2014.

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Abstract. Tornadoes have been reported in Greece during the last decades and recent studies have given evidence that west Greece is a vulnerable area for tornadoes, waterspouts and funnel clouds to occur. In this study, the composite means and anomalies of synoptic conditions for tornadic events (tornadoes, waterspouts and funnel clouds) over west Greece are analyzed and discussed. The daily composite means of synoptic conditions were based on National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP/NCAR) reanalysis datasets, for the period 12 August 1953 to 31 December 2012. The daily composite anomalies were calculated with respect to 30 years climatology (1981–2010) of the synoptic conditions. The analysis was carried out in terms of seasonal and monthly variability of composite means and anomalies of synoptic conditions for specific isobaric levels of 500, 700, 850, 925 hPa and the sea level pressure (SLP). In addition, an analysis and discussion about the dynamic Lifted Index from NCEP/NCAR Reanalysis datasets is presented.
2

Wu, Renguang, Yuqi Wang, and Xi Cao. "What Modulates the Intensity of Synoptic-Scale Variability over the Western North Pacific during Boreal Summer and Fall?" Journal of Climate 34, no. 9 (May 2021): 3645–62. http://dx.doi.org/10.1175/jcli-d-20-0477.1.

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AbstractThe present study investigates the factors that affect the year-to-year change in the intensity of synoptic-scale variability (SSV) over the tropical western North Pacific (TWNP) during boreal summer and fall. It is found that the intensity of the TWNP SSV in summer is associated with the equatorial central-eastern Pacific sea surface temperature (SST) anomalies that modulate the background fields through a Rossby wave response both in the source region and along the propagation path of the synoptic-scale disturbances. In fall, the intensity of the TWNP SSV is related to an SST anomaly pattern with opposite anomalies in the equatorial central Pacific and TWNP that modulates the background fields from the equatorial central Pacific to TWNP. However, the equatorial central Pacific SST anomalies alone fail to change the intensity of the TWNP SSV as the induced background field changes are limited to the equatorial central Pacific. It is shown that tropical western Pacific SST anomalies may induce notable changes in the intensity of the TWNP SSV. The relation of the TWNP SSV to the equatorial eastern Pacific SST is weak due to opposite SST anomalies in different types of years. Both seasonal mean and intraseasonal flows provide sources of barotropic energy for the change in the intensity of the TWNP synoptic-scale disturbances in summer. Seasonal mean flow has a main contribution to the barotropic energy conversion for the change in the intensity of the TWNP synoptic-scale disturbances in fall.
3

Kaspar, M., and M. Müller. "Cyclogenesis in the Mediterranean basin: a diagnosis using synoptic-dynamic anomalies." Natural Hazards and Earth System Sciences 9, no. 3 (June 2009): 957–65. http://dx.doi.org/10.5194/nhess-9-957-2009.

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Abstract. This work deals with the hypothesis that synoptically-driven heavy rains in the Mediterranean region are connected with the occurrence of synoptic-dynamic anomalies. We investigate this hypothesis by conducting a diagnostic study of a cyclogenesis event from 18–21 July 2001. Cyclogenesis started over the western Mediterranean Sea and was triggered by the approach of a pre-existing upper trough over a lower frontal zone. The event was first accompanied by heavy convective rains in northern Italy and later by heavy, widespread and steady rains of non-convective character in Central Europe. Using re-analyses from the database ERA-40, we evaluate the synoptic-dynamic anomalies by the cumulative distribution function relatively to July–August area-related climatology over the reference period from 1958 to 2002. For the duration of cyclogenesis, we detect significant anomalies associated with the processes that support the completion of vertical coupling between the lower frontal zone and the upper vorticity maximum. The periods of heavy rains in both the Mediterranean region and Central Europe were characterised by the occurrence of anomalies that created synoptic-scale conditions favourable for triggering and sustaining heavy rains. Although these anomalies were somewhat weaker in the period of heavy rains in Central Europe than in the Mediterranean region, the analysis of their spatio-temporal correspondence over the reference rainfall events in the Czech Republic shows that they are typical of heavy rains there. Due to the relatively high variability of the causal synoptic-scale conditions, this study would benefit post-processing procedures aimed at improving warning about this hazardous weather phenomenon to further investigate which anomalies generally occur during synoptically-driven heavy rains in the Mediterranean region and the strengths of these anomalies.
4

Nastos, P. T., and I. T. Matsangouras. "Analysis of synoptic conditions for tornadic days over western Greece." Natural Hazards and Earth System Sciences 14, no. 9 (September 2014): 2409–21. http://dx.doi.org/10.5194/nhess-14-2409-2014.

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Abstract. Tornadoes have been reported in Greece during the last few decades and recent studies have given evidence that western Greece is an area vulnerable to tornadoes, waterspouts and funnel clouds In this study, the composite means and anomalies of synoptic conditions for tornadic events (tornadoes, waterspouts and funnel clouds) over western Greece are analyzed and discussed. The daily composite means of synoptic conditions were based on the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis data sets, for the period 12 August 1953 to 31 December 2012. The daily composite anomalies were calculated with respect to 30 years of climatological study (1981–2010) of the synoptic conditions. The analysis was carried out in terms of seasonal and monthly variability of composite means and anomalies of synoptic conditions for specific isobaric levels of 500, 700, 850, 925 hPa and the sea level pressure (SLP). In addition, an analysis and discussion about the dynamic lifted index from NCEP–NCAR reanalysis data sets is presented. The daily composite mean analysis of 500 hPa revealed a trough line across the northern Adriatic Sea and central Italy, associated with a SW upper-air stream over western Greece. The maximum composite anomalies were depicted at the isobaric level of 500 hPa during autumn, spring and summer, against winter when the anomaly appeared at 925 hPa isobaric level. In addition, 48% of tornado events during the autumn season occurred in pre-frontal weather conditions (cold fronts) and 27% developed after the passage of the cold front. Furthermore, the main difference in synoptic patterns between tornado and waterspout days along western Greece during the autumn season is the maximum daily composite anomaly over the Gulf of Taranto.
5

Naumenko, M. A., and L. A. Timofeeva. "Synoptic-scale anomalies of Lake Ladoga surface temperature fields." Russian Meteorology and Hydrology 34, no. 12 (December 2009): 828–34. http://dx.doi.org/10.3103/s1068373909120085.

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6

Jaffe, Sharon C., Jonathan E. Martin, Daniel J. Vimont, and David J. Lorenz. "A Synoptic Climatology of Episodic, Subseasonal Retractions of the Pacific Jet." Journal of Climate 24, no. 11 (June 2011): 2846–60. http://dx.doi.org/10.1175/2010jcli3995.1.

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Abstract Twenty-eight years of NCEP–NCAR reanalysis data are employed in a composite analysis of the structure and evolution of the large-scale circulation associated with rapid, subseasonal, westward retractions of the Northern Hemisphere Pacific jet. Nineteen Pacific jet retractions are identified in the dataset. The salient characteristics of these transitions are presented, emphasizing the structure and evolution of anomalies in the zonal wind, upper-tropospheric geopotential height, sea level pressure (SLP), and tropopause potential vorticity (PV). The composite analysis demonstrates that as the jet retracts, a transition from a dominant negative anomaly to a dominant positive anomaly across the North Pacific in both the 500-hPa geopotential height and SLP fields occurs in ~10 days. The resulting anticyclonic anomalies are sprawling and intense with SLP anomalies of nearly 20 hPa and 500-hPa geopotential height anomalies of more than 200 m. The vertical superposition of these upper- and lower-level anomalies indicates that these composite structures are equivalent barotropic. These results are also consistent with the composite 200–250-hPa Ertel PV anomaly field, in which a jet retraction event is characterized by the formation of a zonally elongated, meridionally oriented PV anomaly couplet in the central North Pacific that becomes increasingly isotropic in the jet exit region simultaneous with the retraction of the jet. Because of the large spatial scale of these events, the results are also discussed in the context of storm-track variability, the East Asian winter monsoon, and tropical diabatic heating anomalies.
7

Lee, Min-Hee, and Joo-Hong Kim. "The Role of Synoptic Cyclones for the Formation of Arctic Summer Circulation Patterns as Clustered by Self-Organizing Maps." Atmosphere 10, no. 8 (August 2019): 474. http://dx.doi.org/10.3390/atmos10080474.

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Contribution of extra-tropical synoptic cyclones to the formation of mean summer atmospheric circulation patterns in the Arctic domain (≥60° N) was investigated by clustering dominant Arctic circulation patterns based on daily mean sea-level pressure using self-organizing maps (SOMs). Three SOM patterns were identified; one pattern had prevalent low-pressure anomalies in the Arctic Circle (SOM1), while two exhibited opposite dipoles with primary high-pressure anomalies covering the Arctic Ocean (SOM2 and SOM3). The time series of their occurrence frequencies demonstrated the largest inter-annual variation in SOM1, a slight decreasing trend in SOM2, and the abrupt upswing after 2007 in SOM3. Analyses of synoptic cyclone activity using the cyclone track data confirmed the vital contribution of synoptic cyclones to the formation of large-scale patterns. Arctic cyclone activity was enhanced in the SOM1, which was consistent with the meridional temperature gradient increases over the land–Arctic ocean boundaries co-located with major cyclone pathways. The composite daily synoptic evolution of each SOM revealed that all three SOMs persisted for less than five days on average. These evolutionary short-term weather patterns have substantial variability at inter-annual and longer timescales. Therefore, the synoptic-scale activity is central to forming the seasonal-mean climate of the Arctic.
8

Udy, Danielle G., Tessa R. Vance, Anthony S. Kiem, Neil J. Holbrook, and Mark A. J. Curran. "Links between Large-Scale Modes of Climate Variability and Synoptic Weather Patterns in the Southern Indian Ocean." Journal of Climate 34, no. 3 (February 2021): 883–99. http://dx.doi.org/10.1175/jcli-d-20-0297.1.

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AbstractWeather systems in the southern Indian Ocean (SIO) drive synoptic-scale precipitation variability in East Antarctica and southern Australia. Improved understanding of these dynamical linkages is beneficial to diagnose long-term climate changes from climate proxy records as well as informing regional weather and climate forecasts. Self-organizing maps (SOMs) are used to group daily 500-hPa geopotential height (z500; ERA-Interim) anomalies into nine regional synoptic types based on their dominant patterns over the SIO (30°–75°S, 40°–180°E) from January 1979 to October 2018. The pattern anomalies represented include four meridional, three mixed meridional–zonal, one zonal, and one transitional node. The frequency of the meridional nodes shows limited association with the phase of the southern annular mode (SAM), especially during September–November. The zonal and mixed patterns were nevertheless strongly and significantly correlated with SAM, although the regional synoptic representation of SAM+ conditions was not zonally symmetric and was represented by three separate nodes. We recommend consideration of how different synoptic conditions vary the atmospheric representation of SAM+ in any given season in the SIO. These different types of SAM+ mean a hemispheric index fails to capture the regional variability in surface weather conditions that is primarily driven by the synoptic variability rather than the absolute polarity of the SAM.
9

Kim, Jineun, Donghyuck Yoon, Dong-Hyun Cha, Yonghan Choi, Joowan Kim, and Seok-Woo Son. "Impacts of the East Asian Winter Monsoon and Local Sea Surface Temperature on Heavy Snowfall over the Yeongdong Region." Journal of Climate 32, no. 20 (September 2019): 6783–802. http://dx.doi.org/10.1175/jcli-d-18-0411.1.

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Abstract This research investigates the impact of local sea surface temperature (SST) on the 2-month (January and February) accumulated snowfall over the Yeongdong (YD) region. The YD region is strongly affected by synoptic-scale factors such as the East Asian winter monsoon (EAWM). The relationships of snowfall over the YD region to the EAWM and local SST are examined based on observational analyses and sensitivity experiments using a regional climate model. In the sensitivity experiments, local SST is replaced with the 33-yr mean winter SST (1982–2014). The observational analysis shows that both the synoptic environment and local SST are important factors for the occurrence of anomalous heavy snowfall over the YD region. The favorable synoptic environments can be characterized by eastward expansion of the Siberian high over Manchuria and corresponding enhancement of easterly anomalies over the YD region. These conditions are more frequently observed during the weak EAWM years than during the strong EAWM. Furthermore, warm SST over the East Sea contributes to heavy snowfall over the YD region by providing heat and moisture in the lower troposphere, which are important sources of energy for the formation of heavy snowfall. Warm SST anomalies over the East Sea enhance low-level moisture convergence over the YD region, while cold SST anomalies lead to reduced moisture convergence. Sensitivity experiments indicate that local SST can significantly affect snowfall amount over the YD region when the synoptic environments are favorable. However, without these synoptic conditions (expansion of the Siberian high and easterly inflow), the impact of local SST on the snowfall over the YD region is not significant.
10

Plu, Matthieu, Philippe Arbogast, and Alain Joly. "A Wavelet Representation of Synoptic-Scale Coherent Structures." Journal of the Atmospheric Sciences 65, no. 10 (October 2008): 3116–38. http://dx.doi.org/10.1175/2008jas2618.1.

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Midlatitude cyclogenesis as interpreted in the framework of either baroclinic development or potential vorticity thinking heavily relies on the concept of synoptic-scale anomaly. Given the existence of potential vorticity inversion and attribution, what is at stake to provide a mathematical definition for this concept is a complete finite-amplitude alternative to the linear-based theory of cyclogenesis. The existence of a reasonably objective way to represent anomalies in both real and idealized flows would not only help understanding cyclogenesis, it would also have many other applications for both theory and in practical forecasts. Inspired by the recent theory of wavelet representation of coherent structures in two-dimensional fluid mechanics, a wavelet representation of three-dimensional potential vorticity anomalies is built. This algorithm relies on the selection of the appropriate two-dimensional wavelet coefficients from the stationary wavelet transform in order to guarantee the critical translation-invariance property. The sensitivity of the algorithm to the position, size, and shape of the structures is assessed. The wavelet extraction is then applied to the upper-level precursor of a real-case storm of December 1999 and is compared to a basic monopolar extraction. Using potential vorticity inversion and forecasts with a primitive-equation model, it is found that both anomalies have similar implications on the development of the surface cyclone. However, the coherence in time of the extracted wavelet structure in the forecast and analysis sequence is more satisfactory than the extracted monopole: this suggests that the underlying mathematical description of an anomaly proposed here does, indeed, point toward the direction of an actual physical reality of the concept.

Дисертації з теми "Synoptic anomalies":

1

Evans, Katherine J. "A quantitative analysis of the physical mechanisms governing the life cycles of persistent flow anomalies." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/26013.

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2

Neilley, Peter Paul. "Interactions between synoptic-scale eddies and the large-scale flow during the life cycles of persistent flow anomalies." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/54966.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1990.
Includes bibliographical references (p. 259-267).
by Peter Paul Neilley.
Ph.D.
3

Ballinger, Thomas J. "A Synoptic Climatological Assessment of the Relationship between Arctic Sea Ice Variability and Climate Anomalies over North America." Text, Kent State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=kent1428419284.

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4

Rousseau, Victor. "Étude des interactions océan-atmosphère sur le Gulf Stream : apport de la haute résolution sur la représentation des mécanismes physiques et des impacts climatiques." Electronic Thesis or Diss., Toulouse 3, 2020. http://www.theses.fr/2020TOU30318.

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Le but de cette thèse est de comprendre le rôle des fronts de température de surface de l'océan (SST) dans les interactions océan-atmosphère sur la région du Gulf Stream (GS). Nous étudions la réponse de l'atmosphère aux fronts de SST localement, au sein de la couche limite atmosphérique marine (MABL), mais également dans la troposphère libre. Par ailleurs, nous quantifions l'impact des fronts de SST sur la circulation atmosphérique en Atlantique Nord et en Europe. Nous nous focalisons sur la saison d'hiver (Décembre-Janvier-Février), les contrastes de température entre l'océan et l'atmosphère étant les plus marqués durant cette saison, ce qui induit de forts échanges en termes de flux de chaleur turbulents. Dans cette optique, nous réalisons et analysons des expériences numériques basées sur le modèle atmosphérique global ARPEGEv6, forcé en surface par des données de SSTs observées à haute résolution (1/4°). Dans la première partie de cette thèse, nous étudions les deux mécanismes principaux proposés dans la littérature pour expliquer la réponse de l'atmosphère aux fronts de SST dans la région du Gulf Stream. Ces mécanismes sont ceux du mélange vertical et de l'ajustement de pression. Dans cette étude, nous utilisons deux ensembles de simulations réalisées avec deux configurations du modèle d'atmosphère ARPEGEv6 : une configuration basse résolution (140 km) et une configuration haute résolution (50 km). Nous étudions spécifiquement la réponse de la divergence du vent en surface, un prédicteur important de l'influence des fronts de SST sur la MABL. Là où les études antérieures utilisaient majoritairement des moyennes mensuelles pour étudier la réponse de la divergence du vent aux fronts de SST, nos résultats montrent le rôle clé des perturbations synoptiques atmosphériques pour moduler la contribution relative de chacun de ces deux mécanismes de la MABL, et pour générer de la divergence du vent de surface en hiver. Nous montrons plus particulièrement qu’une grande partie de la divergence du vent simulée en moyenne sur l’hiver est due aux épisodes cycloniques qui ont lieu au cours de situations extrêmes au-dessus de la région du GS. La comparaison des résultats entre la version haute et la version basse résolution du modèle atmosphérique, montre que l'impact de l'augmentation de la résolution du modèle est faible comparée à la variabilité interne climatique et aux incertitudes observationnelles. Afin de mieux isoler l'influence des fronts de SST sur l’atmosphère, nous avons réalisé des expériences idéalisées dans lesquelles les SSTs de la région du GS sont spatialement filtrées. Cette expérience « lissée » ("smooth") est comparée à une expérience de contrôle dans laquelle le même modèle d'atmosphère est forcé à l'échelle globale par des SSTs à très haute résolution (1/12°). La comparaison entre ces deux expériences montre que la variabilité liée à la zone de fronts de SST influence localement les mécanismes de la MABL, mais également la troposphère libre dans son ensemble. En particulier, la bande de précipitations sur le GS est atténuée dans l'expérience smooth. Un gradient de SST mieux résolu dans la région du GS affecte également les routes dépressionnaires et les transports de chaleur et d'humidité par les tourbillons atmosphériques. En particulier, on montre que les fronts de SST provoquent un décalage vers le nord des transports de chaleur et d'humidité par les tourbillons atmosphériques. Ceci est en accord avec un élargissement du courant jet. La réponse du jet la plus intense est située sur l'Atlantique Nord, mais est également visible sur le bassin Pacifique. On montre ensuite qu'en accord avec la réponse du courant jet, les régimes de temps en Atlantique Nord sont également influencés par la présence des fronts de SST [...]
This thesis aims at understanding the role of sea surface temperature (SST) fronts on air-sea interactions in the Gulf Stream region. We study the local response of the atmosphere to the SST mesoscale variability, not only within the marine atmospheric boundary layer (MABL), but also in the free troposphere. We also evaluate the impact of SST fronts beyond the Gulf Stream region, in particular on the North Atlantic atmospheric circulation and climate over Europe. We focus on the winter season (December-January-February), when air-sea contrasts and hence air-sea exchanges are the strongest. On this purpose, we perform and analyze numerical experiments, using the global atmospheric model ARPEGEv6 forced by observed daily SSTs at high resolution (1/4°). In the first part of this thesis we investigate two major MABL mechanisms responsible for the atmospheric response to the SST fronts over the Gulf Stream region. These mechanisms are the vertical mixing and the pressure adjustment mechanisms. Two sets of atmospheric simulations performed with two ARPEGEv6 configurations are considered: a low-resolution version (140 km) and a high resolution version (50 km). We analyze the response of the divergence of the near surface wind, because this is one of the main imprint of the MABL response to the SST front. While in most of previous studies monthly averages were used to study the response of the wind divergence to the SST fronts, our results highlight the key role of synoptic atmospheric perturbations on modulating the contribution of these two MABL mechanisms and hence on shaping the time-mean divergence of near surface wind. We show in particular that most of the winter-mean wind divergence simulated above the Gulf Stream region can be explained by the cyclonic anomalous circulation that occurs during extreme conditions of heat flux exchanges. The comparison of the results obtained with the high and low resolution versions of the atmospheric model shows that the impact of model resolution is small compared to internal climate variability and observational uncertainties in the Gulf Stream region. In order to better isolate the influence of the SST fronts on the atmosphere, we then performed idealized numerical experiments in which the SSTs are spatially filtered only over the Gulf Stream region. This "smooth" experiment is compared with a control experiment in which the atmospheric model is globally forced by very high resolution observed SSTs (1/12°). The comparison between these two experiments shows that SST fronts variability locally influence not only the MABL mechanisms, but also the free troposphere. In particular, the precipitation band over the Gulf Stream is decreased in the smooth experiment. A better resolved SST gradient in the Gulf Stream also yields changes in the storm-tracks and in the associated heat and humidity eddy transports. In particular, we find that the Gulf Stream SST front induces a northward shift of the eddy heat and humidity transports. This shift is consistent with a poleward shift of the jet stream. The jet response is maximum over the North Atlantic, but it is also noticeable over the Pacific basin. We show that together with the jet stream changes, weather regimes in the North Atlantic are also influenced by the SST fronts. As a result, the response of the large scale atmospheric circulation yields changes in temperature and precipitation over Europe, suggesting a non negligible influence of the Gulf Stream SST fronts downstream

Книги з теми "Synoptic anomalies":

1

Tibaldi, Stefano, and Franco Molteni. Atmospheric Blocking in Observation and Models. Oxford University Press, 2018. http://dx.doi.org/10.1093/acrefore/9780190228620.013.611.

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The atmospheric circulation in the mid-latitudes of both hemispheres is usually dominated by westerly winds and by planetary-scale and shorter-scale synoptic waves, moving mostly from west to east. A remarkable and frequent exception to this “usual” behavior is atmospheric blocking. Blocking occurs when the usual zonal flow is hindered by the establishment of a large-amplitude, quasi-stationary, high-pressure meridional circulation structure which “blocks” the flow of the westerlies and the progression of the atmospheric waves and disturbances embedded in them. Such blocking structures can have lifetimes varying from a few days to several weeks in the most extreme cases. Their presence can strongly affect the weather of large portions of the mid-latitudes, leading to the establishment of anomalous meteorological conditions. These can take the form of strong precipitation episodes or persistent anticyclonic regimes, leading in turn to floods, extreme cold spells, heat waves, or short-lived droughts. Even air quality can be strongly influenced by the establishment of atmospheric blocking, with episodes of high concentrations of low-level ozone in summer and of particulate matter and other air pollutants in winter, particularly in highly populated urban areas.Atmospheric blocking has the tendency to occur more often in winter and in certain longitudinal quadrants, notably the Euro-Atlantic and the Pacific sectors of the Northern Hemisphere. In the Southern Hemisphere, blocking episodes are generally less frequent, and the longitudinal localization is less pronounced than in the Northern Hemisphere.Blocking has aroused the interest of atmospheric scientists since the middle of the last century, with the pioneering observational works of Berggren, Bolin, Rossby, and Rex, and has become the subject of innumerable observational and theoretical studies. The purpose of such studies was originally to find a commonly accepted structural and phenomenological definition of atmospheric blocking. The investigations went on to study blocking climatology in terms of the geographical distribution of its frequency of occurrence and the associated seasonal and inter-annual variability. Well into the second half of the 20th century, a large number of theoretical dynamic works on blocking formation and maintenance started appearing in the literature. Such theoretical studies explored a wide range of possible dynamic mechanisms, including large-amplitude planetary-scale wave dynamics, including Rossby wave breaking, multiple equilibria circulation regimes, large-scale forcing of anticyclones by synoptic-scale eddies, finite-amplitude non-linear instability theory, and influence of sea surface temperature anomalies, to name but a few. However, to date no unique theoretical model of atmospheric blocking has been formulated that can account for all of its observational characteristics.When numerical, global short- and medium-range weather predictions started being produced operationally, and with the establishment, in the late 1970s and early 1980s, of the European Centre for Medium-Range Weather Forecasts, it quickly became of relevance to assess the capability of numerical models to predict blocking with the correct space-time characteristics (e.g., location, time of onset, life span, and decay). Early studies showed that models had difficulties in correctly representing blocking as well as in connection with their large systematic (mean) errors.Despite enormous improvements in the ability of numerical models to represent atmospheric dynamics, blocking remains a challenge for global weather prediction and climate simulation models. Such modeling deficiencies have negative consequences not only for our ability to represent the observed climate but also for the possibility of producing high-quality seasonal-to-decadal predictions. For such predictions, representing the correct space-time statistics of blocking occurrence is, especially for certain geographical areas, extremely important.

Частини книг з теми "Synoptic anomalies":

1

Brazel, Anthony J., and Andrew W. Ellis. "The Climate of the Central Arizona and Phoenix Long-Term Ecological Research Site (CAP LTER) and Links to ENSO." In Climate Variability and Ecosystem Response in Long-Term Ecological Research Sites. Oxford University Press, 2003. http://dx.doi.org/10.1093/oso/9780195150599.003.0016.

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The Central Arizona and Phoenix LTER (CAP LTER) is one of two urban LTERs in the world network (Grimm et al. 2000; see http://caplter.asu.edu). Many LTER sites display a detectable climatic signal related to the El Niño–Southern Oscillation (ENSO) phenomenon (Greenland 1999). The purpose of this chapter is twofold: (1) to provide some insight into the role of the tropical Pacific Ocean as a driver of several climatic (and thus, ecologically related) variables in the CAP LTER location of central Arizona, and (2) to suggest the linkages of ENSO events to selected ecosystem processes near and within the geographical region of CAP LTER (figure 7.1a). From past studies, it is clear that the seasonal and annual climate regimes of the southwestern United States, particularly water-related parameters, are linked to the periodicities and anomalies of what is known as the Multivariate ENSO Index (MEI) and Southern Oscillation Index (SOI) (e.g., Wolter 1987; Molles and Dahm 1990; Redmond and Koch 1991; Woolhiser and Keefer 1993; Wolter and Timlin 1993; Cayan and Redmond 1994; Redmond and Cayan 1994; Cayan et al. 1999; Redmond and Cayan 1999; Simpson and Colodner 1999; Redmond 2000; and Mason and Goddard 2001). In Arizona, and especially in the CAP LTER region, precipitation is bimodal during the year with peaks in winter (mostly midlatitudederived frontal storms) and in mid-to-late summer, mostly in the form of convective thunderstorms during the North American monsoon season. Recent studies show a strong connection between ENSO and winter moisture in Arizona, such that it is even possible to forecast impending conditions in advance (Pagano et al. 1999). These studies have established relationships between the climate of the southwest ern United States and ENSO by demonstrating monthly and daily timescale effects on inputs of moisture and resultant streamflow in Arizona (e.g., Molles and Dahm 1990; Cayan et al. 1999; and Simpson and Colodner 1999). The synoptic- and largescale circulation patterns associated with anomalies of MEI/SOI in the southwestern United States provide additional insight into regional forces that drive the CAPLTER climate (e.g., Redmond and Koch 1991). Generally, when the warm phase of the tropical Pacific Ocean occurs (El Niño, thus negative SOI, positive MEI), across the Southwest precipitation is generally anomalously high.
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Kanski, Jack J. "Developmental Malformations and Anomalies." In Clinical Ophthalmology: A Synopsis, 35–52. Elsevier, 2009. http://dx.doi.org/10.1016/b978-0-7020-3135-9.50008-2.

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MARTIN-DOYLE, J. L. C. "ANOMALIES OF OCULAR MOVEMENTS." In A Synopsis of Ophthalmology, 170–84. Elsevier, 2013. http://dx.doi.org/10.1016/b978-1-4832-3103-7.50020-2.

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MARTIN-DOYLE, J. L. C. "OPTICAL ANOMALIES OF THE EYE." In A Synopsis of Ophthalmology, 162–69. Elsevier, 2013. http://dx.doi.org/10.1016/b978-1-4832-3103-7.50019-6.

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Rendle-Short, John, O. P. Gray, and J. A. Dodge. "CONGENITAL ANOMALIES OF THE RENAL TRACT." In A Synopsis of Children's Diseases, 392–95. Elsevier, 1985. http://dx.doi.org/10.1016/b978-1-4831-8407-4.50128-0.

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