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The current study looks at how the characteristics of Arabian Sea tropical cyclones (TCs) change over time. The results show that in the pre-monsoon (April–June) and the post-monsoon (October–December), the activity of TCs > 34 knots, including cyclonic storm (CS), severe cyclonic storm (SCS), very severe cyclonic storm (VSCS), extreme severe cyclonic storm (ESCS), and super cyclonic storm (Sup. CS), has significantly increased, while the tendency of TCs < 34 knots, depressions and deep depressions (Ds) over the Arabian Sea has only slightly increased. Most of the TC activity in the first two decades (1982–2001) over the Arabian Sea activated on the eastern side, while in the last two decades (2002–2021), there was an expansion toward the southwest region of the Arabian Sea, especially in the post-monsoon season. The composite analysis of environmental parameters over the Arabian Sea reveals that the negative anomalies of outgoing longwave radiation (OLR) and the positive anomalies of relative humidity at 500 hPa (RH–500 hPa) in the first decade (1982–1991) and the second decade (1992–2001) are more concentrated on the eastern side of the Arabian Sea, leading to increased activity for TCs. Decades three (2002–2011) and four (2012–2021) demonstrated a wide distribution of weak vertical wind shear (VWS) and strong convection (OLR and RH–500 hPa) over the Arabian Sea basin. This led to TCs occurring more frequently and stronger, especially in the post-monsoon season. SST over the Arabian Sea was sufficient for tropical storm activity (≥26.5 °C) for both typical seasons. [ABSTRACT FROM AUTHOR]

Based on the conventional observation， the cloud top blackbody brightness temperature data of Fengyun satellite， and the European Centre for Medium-Range Weather Forecasts 0.25°×0.25° ERA5 reanalysis data from 2006 to 2021， we have conducted a statistical analysis on the heavy precipitation events caused by extratropical cyclones over northern and northeastern China during the cold season.The results show that： （1） Most of the extratropical cyclones occluded during the explosive development phase， but the development process is different， with the Shapiro-Keyser （SK-type） and the classical Norwegian （NW-type） cyclones each accounting for half.The SK-type cyclone has a deep trough at 500 hPa， strong baroclinicity， and steering airflow in the north-northeast-orientation， resulting in westerly cyclone path， and northward， widespread precipitation； the NW-type cyclone has a shallow trough at 500 hPa， with weak cold advection behind the trough， and the steering airflow in the east-northeast orientation， resulting in an easterly cyclone path， more to the south and more intense precipitation.（2） The atmospheric rivers of the NW-type cyclone are more intensethan those of the SK-type cyclone， and the corresponding heavy precipitation is extensive and more intense.With the development of the cyclones， the atmospheric rivers of the SK-type cyclone gradually turn to a north-south orientation， and there is a clear backward-turning feature on the north side of the atmospheric river， resulting in a warm front precipitation center of the SK-type cyclone located in the northwest quadrant of the cyclone， and the warm front precipitation center of the NW-type cyclone is close to the center of the cyclones.（3） The warm front frontogenesis in the northwest quadrant of the SK-type cyclone is significantly more intense than that of the NW-type cyclone， and the intense lifting forced by the front is conducive to heavy snowfall.（4） The SK-type cyclone has an intense potential vorticity structure in the shape of treble-clef at 300 hPa， while the NW-type cyclone has weaker potential vorticity in the upper levels.The stratospheric potential vorticity over the SK-type cyclone extends downwards， connecting with the low-level potential vorticity to form a potential vorticity tower， with a deep warm occluded structure nearby； while， the upper-level potential vorticity of the NW-type cyclone does not extend downward significantly， and there is no potential vorticity tower generated.The SK-type cyclone first develops in the middle troposphere， and then reachesthe surface， while the NW-type cyclone develops from the lower troposphere.

This study aims to characterize how eddies shape the biogeochemistry of the Mozambique Channel using a physical-biogeochemical model that realistically simulates its interannual dynamics. The 20-year-long numerical simulation provides a comprehensive dataset for robust statistical analysis of thousands of mesoscale features using an eddy detection method. We show that all eddy types significantly shape the biogeochemical landscape over the Mozambique Channel, with varying effects across different areas: (1) Sofala Bank and Delagoa Bay: Cyclonic eddies enhance diatom production. (2) Comoros Basin: Cyclonic eddies favor diatom growth via nutrient-rich waters from the NEMC. (3) Central Mozambique Channel: Anticyclonic eddies and rings promote nanophytoplankton through eddy-topography interactions. (4) Southern Mozambique Channel: A mix of eddies from the MC and South Madagascar influences diverse responses due to coastal upwelling. This diversity of processes results in distinct biological signatures of eddy types, leading to diverse ecosystem assemblages with a clear oligotrophic signature. [ABSTRACT FROM AUTHOR]

Conventional wisdom about mesoscale eddies is that cyclonic (anticyclonic) eddies are commonly associated with cold(warm) surface cores. Nevertheless, plenties of surface warm cyclonic eddies (WCEs) and cold anticyclonic eddies (CAEs) in the North Pacific Subtropical Countercurrent (STCC) region are observed by a synergistic investigation based on data from satellite altimetry, microwave radiometer, and Argo float profiles in this study. The results indicate that these two types of abnormal eddies (WCEs and CAEs) are prevalent in the STCC region, comprising approximately 30% of all eddies detected via satellite observations. We then analyze their spatial-temporal distribution characteristics and composite vertical structures. A statistical comparison with surface cold cyclonic eddies (CCEs) and warm anticyclonic eddies (WAEs) reveals notable differences between the anomalous and typical eddies. Additionally, we present the composite vertical structures of temperature and salinity anomalies for the anomalous eddies across five delineated subregions within an eddy-coordinate system. Furthermore, the close relationship between these abnormal eddies and subsurface-intensified mesoscale eddies are discussed. [ABSTRACT FROM AUTHOR]

Copyright of Plateau Meteorology is the property of Plateau Meteorology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

For the first time, the relationships between large-scale weather types and local stroke events in the urban area of Augsburg, Germany are analyzed. Over 23,000 stroke cases (2006 – 2020) were standardized to account for long-term trends and seasonality. Using ERA5 reanalysis data, a composite analysis identified stroke-related atmospheric variables, while seasonal weather types were classified via the neural network algorithm of self-organizing maps. Cyclonic westerlies during the cold season, which transport warm air masses from the Atlantic Ocean to Germany, were a major risk factor for ischemic stroke, while colder easterly conditions reduced stroke incidence. In the warm season, both anticyclonic conditions and westerly/northerly air advection, leading to slightly warmer or distinctly colder temperatures, were linked to increased ischemic stroke risk. Additionally, hemorrhagic strokes in the cold season were triggered by weather conditions contrary to those associated with ischemic strokes and transitory ischemic attacks. [ABSTRACT FROM AUTHOR]

Mesoscale eddies are known to enhance diapycnal mixing in the ocean, yet direct observation of this effect remains a significant challenge, especially in the robust Antarctic Circumpolar Current (ACC). To quantify the diapycnal mixing induced by mesoscale eddies in the standing meander of the ACC, satellite altimeter and Argo profile data were combined to composite eddies, where the 1.6 m dynamic height contour was used for the first time instead of the climatological Northern Sub-Antarctic Front (SAFN) to define the northern boundary of the ACC to eliminate the influence of frontal shift. The 3D structures of the composite anticyclonic/cyclonic eddy (CAE/CCE) were obtained. Both the CAE and CCE were similar in shape to Taylor columns, from sea surface to the neutral surface of 28.085 kgm − 3 (1689 ± 66 dbar) for the CAE, and from sea surface to 28.01 kgm − 3 (1491 ± 202 dbar) for the CCE. On the same neutral surface, the diffusivity (κ) inside the CCE was one to two orders of magnitude higher than that inside the CAE. Vertically, the maximum influence depth of the CCE on κ reached 1200 dbar, while for the CAE, it reached 800 dbar, where κ exceeded O (10 − 4)   m 2 s − 1 , and κ gradually decreased from these depths downwards. [ABSTRACT FROM AUTHOR]

This study aims to characterize how eddies shape the biogeochemistry of the Mozambique Channel using a physical-biogeochemical model that realistically simulates its interannual dynamics. The 20-year-long numerical simulation provides a comprehensive dataset for robust statistical analysis of thousands of mesoscale features using an eddy detection method. We show that all eddy types significantly shape the biogeochemical landscape over the Mozambique Channel, with varying effects across different areas: (1) Sofala Bank and Delagoa Bay: Cyclonic eddies enhance diatom production. (2) Comoros Basin: Cyclonic eddies favor diatom growth via nutrient-rich waters from the NEMC. (3) Central Mozambique Channel: Anticyclonic eddies and rings promote nanophytoplankton through eddy-topography interactions. (4) Southern Mozambique Channel: A mix of eddies from the MC and South Madagascar influences diverse responses due to coastal upwelling. This diversity of processes results in distinct biological signatures of eddy types, leading to diverse ecosystem assemblages with a clear oligotrophic signature.

Mesoscale eddies are omnipresent and play an important role in regulating Earth's climate and ocean circulation in the global ocean. Here using the combination of satellite altimetry products and Argo float profile data, two types of abnormal eddies are investigated: WCEs(warm cyclonic eddies) and CAEs(cold anticyclonic eddies) with different cores than conventional eddies in the Japan/East Sea. By applying a classification method based on the calculation of the heat content anomalies in the upper ocean, it was found that 10% of the eddies that captured the Argo float profiles exhibited obvious abnormal features. Subsequently, their spatiotemporal distributions and characteristics were analyzed statistically. Three-dimensional structures of abnormal eddies were obtained via the composite analysis method, showing that the warm/cold and light/dense core of the composite WCE/CAE is confined to the upper 100 m of the ocean with a maximum temperature anomaly of approximately +1.0(-1.1)°C. The composite WCE had a double-core salinity structure with a salty core above 50 m and an inferior fresh core. Meanwhile composite CAE had a fresh singlecore with a maximum magnitude of -0.05 psu. Abnormal eddies are pervasive in the Japan/East sea, a revaluation of the role of these eddies in ocean circulation and climate systems, such as heat and salt transport, air and sea interaction, and variability in mixed layer depth, is of great importance. [ABSTRACT FROM AUTHOR]

Conventional wisdom about mesoscale eddies is that cyclonic (anticyclonic) eddies are commonly associated with cold(warm) surface cores. Nevertheless, plenties of surface warm cyclonic eddies (WCEs) and cold anticyclonic eddies (CAEs) in the North Pacific Subtropical Countercurrent (STCC) region are observed by a synergistic investigation based on data from satellite altimetry, microwave radiometer, and Argo float profiles in this study. The results indicate that these two types of abnormal eddies (WCEs and CAEs) are prevalent in the STCC region, comprising approximately 30% of all eddies detected via satellite observations. We then analyze their spatial-temporal distribution characteristics and composite vertical structures. A statistical comparison with surface cold cyclonic eddies (CCEs) and warm anticyclonic eddies (WAEs) reveals notable differences between the anomalous and typical eddies. Additionally, we present the composite vertical structures of temperature and salinity anomalies for the anomalous eddies across five delineated subregions within an eddy-coordinate system. Furthermore, the close relationship between these abnormal eddies and subsurface-intensified mesoscale eddies are discussed.

Extended Abstract Introduction and Objective:The soybean genotype's stability and high performance are essential factors for long-term development and food security. That the occurrence of various stresses, including drought stress, can cause high losses in the production and supply of this product. This factor has caused the wide attention of researchers to evaluate the stable and tolerant genotypes to drought stress in different environments to introduce the best variety. Materials and Methods: This research investigated the interaction effects of G × E on yield stability in 12 soybean genotypes in four different northern Iran environments. This experiment was conducted as a randomized complete block design with three replications in each environment. During several harvests, yield component traits such as plant height, number of pods, number of seeds per pod, the weight of 1000 seeds, biological yield, harvest index, seed yield, oil percentage, oil yield, and seed protein content were evaluated in 1400 and 1401. Stability tests for multivariate stability parameters were performed based on AMMI and GGE biplot analysis. Results: Among the investigated cultivars, the Sari variety had the highest yield in all three studied regions, and the Hill variety had the lowest yield among the cultivars. The variety Sari in the two environments of Karakhil and Kapik and the varieties Tapur and SBA2 were more compatible with the Bai-Kola region than the rest of the varieties. Sari, Tapur, Caspian, and SBA3 cultivars were in this range. And Telar, Nekader, SBA2, and SBA4 cultivars are in the field of TOL and SSI indices, these cultivars were also identified as drought-sensitive cultivars. Conclusion: In addition to yield stability in the two regions, the Sari variety was tolerant to drought stress and had a higher yield than the rest of the studied varieties. This variety has drought-tolerance genes and is the best parent for transferring these genes. Based on the results of cluster analysis, Hill and SBA6 cultivars had the furthest distance from SBA2. The best parents to improve the generation are crossed to create a diverse population to produce superior cultivars or genotypes.

Using meteorological analysis, composite analysis and water vapor trajectory analysis, the extreme value rainstorm process in northwest Hunan was analyzed. The results show that three types are summarized: the Southwest Vortex and Warm Shear Line Pattern (SVWSLP), the Subtropical High Edge Pattern (SHEP) and the Cold Trough and Shear Line Pattern (CTSLP). The main influence systems are upper trough, southwest vortex, shear line, low-level jet and subtropical high edge. For SVWSLP, the water vapor transport channels are only from the low-latitude ocean whether it is affected by long-distance typhoons. For SHEP, the main water vapor channel comes from the long-distance ocean and is finally transported to northwestern Hunan around 650 hPa in the form of warm and wet airflow, whether it is affected by long-distance typhoons. The CTSLP appears a significant water vapor confrontation between the north and the south and the baroclinicity of the atmosphere in the rainstorm area. The southern and western boundaries are the input boundary, while the eastern and northern boundaries are the outflow boundary. Therefore, one of the three types of weather systems appears in northwestern Hunan in May–August, with strong water vapor transport from the ocean surface, which is likely to cause extreme rainstorm. HIGHLIGHTS Climatic characteristics of extreme precipitation in northwest Hunan.; The terrain of northwest Hunan is complex, and the system extreme value is analyzed for the first time.; The influence of water vapor in northwest Hunan is analyzed by HYSPLT for the first time.; No one has ever studied the influence of long-distance typhoons in northwestern Hunan.; The results are of great significance to the prediction of extreme value rainstorms in northwest Hunan.;

Study region: The arid area of Northwest China. Study focus: This study aims to explore the lagged effects of snow on extreme precipitation and the associated mechanisms by using composite analysis and extracting significant areas. Due to the complex terrain of the study area, we have explored the response of soil temperature, soil moisture, and various energy changes in different sub-regions, these explorations are conducted in conjunction with the study of lagged effects of snow on extreme precipitation and provide a reference for future climate prediction. New hydrological insights for the region: The response pathways of soil and energy are explored during the impact of snow on extreme precipitation in different significant areas. Latent heat flux is the main energy source, but sensible heat flux and effective radiation can also become the local dominant energy sources due to the influence of many environmental factors. Differences in the paths of influence in different regions will result in different atmospheric circulation anomalies. When the low-value system appears, it is more likely to cause extreme precipitation.

A statistical study on snowstorms in northeastern China caused by extratropical cyclones with and without the support of atmospheric rivers （ARs） was conducted using conventional observations， 6-hour and 24-hour precipitation data， as well as ERA5 reanalysis data from the European Center for Medium-Range Weather Forecasts from 2007 to 2020.In addition， the environmental fields in snowstorms with and without ARs support were compared.According to the findings， ARs occurred in 83 percent of snowstorms associated with extratropical cyclones， with 59% of ARs landing in northeastern China.ARs were most common in November and March， with nearly no ARs in December and January.On the one hand， the frequency and intensity of ARs were high during the snowstorms involving the southern and Huanghuai cyclones， and the associated precipitation was heavy.Snowstorms associated with Mongolia cyclones， on the other hand， had a low frequency of ARs and light precipitation.There were two branches of upper-level jets and strong low-level jets for the snowstorms with ARs.And a cold vortex was located at 500 hPa， forming the interaction between the cut-off low and the ARs， which was conducive to heavy rainfall.An obvious warm tongue and strong frontal zones were located at 850 hPa， which was favorable for water vapor transport and dynamic lifting with the support of ARs.And then it rained associated with the cold front and snowed associated with the warm front during snowstorms accompanied by ARs.Compared with snowstorms accompanied by ARs， there was one branch of upper-level jets and weak low-level jets for the snowstorms without ARs.And there was no cold vortex and a weak westerly trough at 500 hPa.The frontal zones and low vortex were weak at 850 hPa without the support of ARs.The upper-level divergence was weak and water vapor was poor， and it mostly snowed associated with the warm front in snowstorm events without ARs support.Water vapor during snowstorms with the support of ARs originated from the East China Sea， the Yellow and Bohai Seas， and the water vapor convergence in the boundary layer was wide and intense， and upward movement was strong with a thick low-level unstable layer.Water vapor during snowstorms without ARs support mainly originated from the Sea of Japan， where unstable stratification and upward movement were weak， and the boundary layer moisture convergence area was narrow and weak.ARs reflect not only strong water vapour transport but also better dynamic lifting.

Heatwaves are among the deadliest weather-related disasters. They are not only seen in summer but also may appear in spring and autumn, especially under climate warming. Although the mechanisms of summertime heatwaves have been extensively studied, how they differ from spring and autumn seasons and possibly season-dependent mechanisms of heatwaves are poorly understood. Here we examine the specific processes associated with spring, summer, and autumn heatwaves in southern China during 1961–2020. We show that heatwaves in all three seasons are intensifying in frequency, duration, and intensity, and they exhibit distinctly season-dependent circulation changes. Summer heatwaves are characterized by a warm-core high-pressure structure, while spring and autumn heatwaves exhibit a warm low pattern. Summer heatwaves are mainly triggered by the westward (eastward) extension of the western North Pacific subtropical high (South Asian high), and are accompanied by anomalous lower-level anticyclone and positive pressure anomalies. In contrast, spring and autumn heatwaves coincide with lower-than-normal pressure and anomalous southwesterly over East Asia, indicative of a weakening of the East Asian winter monsoon circulation and the Siberian high. Their developments are linked to the eastward movement of an upper-tropospheric wave-like pattern over the mid-latitudes. It is also found that autumn heatwaves are largely contributed by local preceding soil moisture deficit, in comparison to spring and summer heatwaves. Our findings contribute to a better understanding of the heatwave characteristics in different seasons and provide insights into their mitigation strategies.

Using an index of tropical easterly wave (TEW) activity derived from spacetime‐filtered outgoing longwave radiation, we construct composites of long‐term hourly surface meteorological observations and morningtime sounding data collected near San José, Costa Rica to investigate how TEWs affect the diurnal cycle of rainfall over land. Our results indicate that TEWs enhance the frequency of occurrence of rain during convectively active conditions over the course of the diurnal cycle. By contrast, rainfall conditional intensity sensitivity to TEW phase appears more nuanced, with indications that active conditions induce a slight delay in the timing of the diurnal peak intensity but a longer duration of heavier rainfall. Analysis of associated hourly surface meteorology along with sounding profiles and derived thermodynamic parameters points to both initial vertical and time‐evolving surface conditions regulating diurnal behavior, such as greater instability and higher precipitable water in morningtime profiles under active phase conditions. Plain Language Summary: Over tropical land, rainfall often follows a characteristic daily (or diurnal) cycle, with a peak in the late afternoon. This study explores how tropical easterly waves, westward‐propagating weather disturbances known to impact rainfall over many parts of the Tropics, affect the rainfall diurnal cycle at a long‐term observation site near San José, Costa Rica. Using an index of tropical easterly wave activity, and considering the diurnal cycle in terms of rainfall occurrence frequency and intensity, the results presented here indicate generally enhanced occurrence frequency over the course of the diurnal cycle during active conditions of tropical easterly waves, while intensity shows a more nuanced behavior, with active phases showing a slight lag in peak diurnal intensity with an overall lengthening of the highest intensities. Such diurnal rainfall sensitivity to tropical easterly waves is interpreted in terms of hourly surface meteorological observations and vertical profiles from morningtime soundings. Key Points: Tropical easterly wave (TEW) impact on the rainfall diurnal cycle over Costa Rica is documented in surface meteorological and sounding dataConvectively active phases of tropical easterly waves are associated with increased hourly rainfall frequency of occurrenceRainfall intensity sensitivity to TEW phase is more subtle, with indications of delayed active phase peak intensity [ABSTRACT FROM AUTHOR]

Warm conveyor belts (WCBs) are rapidly ascending air streams associated with extratropical cyclones. WCBs exert a substantial influence on the evolution of the large‐scale midlatitude flow and have previously been related to increased forecast uncertainty in case studies. This study provides a first systematic investigation of the role of WCBs for errors in medium‐range ensemble forecasts in the Atlantic–European region. The study is enabled through a unique data set, allowing for a Lagrangian detection of WCBs in three years of operational ensemble forecasts from the European Centre for Medium‐Range Weather Forecasts. By analysing the relationship between commonly used error metrics of variables that characterise the large‐scale flow and WCBs, the study aims to shed light on the question of the extent to which WCBs act as a source of forecast errors and as an amplifier of pre‐existing errors in a state‐of‐the‐art global operational numerical weather prediction model. We show that forecasts with high WCB activity are on average characterised by an amplified Rossby‐wave pattern and anticyclonic flow anomalies downstream. We find that the forecast skill is generally reduced when the WCB activity is high, and that WCB activity is particularly increased when the error growth is largest. To establish a causal relationship, we employ two composite approaches. The first focuses on the time of largest error growth and the second calculates normalised forecast error fields centered on WCB objects. Both approaches yield a consistent picture: anomalously high errors are initially associated with misrepresentations of an upstream trough. In regions of WCB ascent and outflow, the errors grow rapidly in terms of magnitude and scale and are projected onto the upper‐level large‐scale circulation. We also find indications that WCBs can cause errors even when the upstream flow is well represented. Notwithstanding, evidence is robust for WCBs acting as an amplifier of forecast uncertainty. [ABSTRACT FROM AUTHOR]

This study uses the empirical orthogonal function (EOF) analysis to identify and describe continental‐scale seasonal (MAM, JJA, SON and DJF) precipitation modes over Africa based on observation (Global Precipitation Climatology Centre; GPCC) and reanalysis (ERA5) data from 1982 to 2014. Using composite analysis, we attempt to identify the atmospheric circulations (wind and relative humidity) associated with each precipitation mode. Precipitation from ERA5 has a good agreement with that of GPCC, as observed in the good spatial congruence in the EOF analysis and precipitation composites. The EOF results for each season show that the loading patterns of Mode 1 (variance >20% for all seasons) match the long‐term mean precipitation distribution. Atmospheric conditions across the continent are primarily driven by the four main high‐pressure systems (Azores, St. Helena, Arabian and Mascarene High) that influence moisture distribution and subsequently modulate the seasonal rain belt distribution. Modes 2 (variance >11% for all seasons) and 3 (variance >10% for all seasons) are deviations of the leading mode associated with smaller‐scale atmospheric systems. However, large‐scale factors still dominate the overall precipitation pattern by modulating the seasonal energy transfer between the hemispheres. The results provide a comprehensive understanding of the continental‐wide African seasonal precipitation modes and the associated atmospheric circulation from observations. The findings can be used as a reference for future work using model data for historical and projection studies. [ABSTRACT FROM AUTHOR]

Introduction and Objective:The soybean genotype's stability and high performance are essential factors for long-term development and food security. That the occurrence of various stresses, including drought stress, can cause high losses in the production and supply of this product. This factor has caused the wide attention of researchers to evaluate the stable and tolerant genotypes to drought stress in different environments to introduce the best variety. Materials and Methods: This research investigated the interaction effects of G × E on yield stability in 12 soybean genotypes in four different northern Iran environments. This experiment was conducted as a randomized complete block design with three replications in each environment. During several harvests, yield component traits such as plant height, number of pods, number of seeds per pod, the weight of 1000 seeds, biological yield, harvest index, seed yield, oil percentage, oil yield, and seed protein content were evaluated in 1400 and 1401. Stability tests for multivariate stability parameters were performed based on AMMI and GGE biplot analysis. Results: Among the investigated cultivars, the Sari variety had the highest yield in all three studied regions, and the Hill variety had the lowest yield among the cultivars. The variety Sari in the two environments of Karakhil and Kapik and the varieties Tapur and SBA2 were more compatible with the Bai-Kola region than the rest of the varieties. Sari, Tapur, Caspian, and SBA3 cultivars were in this range. And Telar, Nekader, SBA2, and SBA4 cultivars are in the field of TOL and SSI indices, these cultivars were also identified as drought-sensitive cultivars. Conclusion: In addition to yield stability in the two regions, the Sari variety was tolerant to drought stress and had a higher yield than the rest of the studied varieties. This variety has drought-tolerance genes and is the best parent for transferring these genes. Based on the results of cluster analysis, Hill and SBA6 cultivars had the furthest distance from SBA2. The best parents to improve the generation are crossed to create a diverse population to produce superior cultivars or genotypes. [ABSTRACT FROM AUTHOR]

Sea surface height anomaly (SSHA) induced by tropical cyclones (TCs) is closely associated with oscillations and is a crucial proxy for thermocline structure and ocean heat content in the upper ocean. The prediction of TC-induced SSHA, however, has been rarely investigated. This study presents a new composite analysis-based random forest (RF) approach to predict daily TC wind pump induced SSHA. The proposed method utilizes TC's characteristics and prestorm upper oceanic parameters as input features to predict TC-induced SSHA up to 30 days after TC passage. Simulation results suggest that the proposed method is skillful at inferring both the amplitude and temporal evolution of SSHA induced by TCs of different intensity groups. Using a TC-centered 5° × 5° box, the proposed method achieves highly accurate prediction of TC-induced SSHA over the Western North Pacific with root mean square error of 0.024 m, outperforming alternative machine learning methods and the numerical model. Moreover, the proposed method also demonstrated good prediction performance in different geographical regions, i.e., the South China Sea and the Western North Pacific subtropical ocean. The study provides insight into the application of machine learning in improving the prediction of SSHA influenced by extreme weather conditions. Accurate prediction of TC-induced SSHA allows for better preparedness and response, reducing the impact of extreme events (e.g., storm surge) on people and property.

As a natural disaster, drought affects many sectors such as agriculture and hydrology, as well as having an effect on air quality. In terms of air pollution, drought can reduce wet scavenging of pollutants and change their chemical production/loss and lifetime. This study investigates the relationship between drought events and air pollutants in Turkey. As a drought indicator, the Standardized Precipitation‐Evapotranspiration Index (SPEI)‐1 monthly values for dry (SPEI < −0.99), normal (−0.99 < SPEI < 0.99) and wet (SPEI < 0.99) conditions were used to investigate the changes in PM10, PM2.5, O3 concentration levels. Monthly mean PM10 values of 80 stations for the period 2010–2018, PM2.5 and O3 values of 10 and 12 stations, respectively, were used for the analysis throughout the 2014–2018 period. According to the results, while frequency occurrence of normal conditions decreased in the last period (2010–2018) when compared to the first (1901–2009), drought conditions have significantly increased in each region of Turkey in the last decade. Highest increase in drought events occurred in the inner/southern parts of Turkey. In dry events, while PM10 levels of the stations show above‐normal values, highest regional increase in PM10 was found in the Central Anatolia (CAR), Mediterranean (MeR), Aegean (AR) and Marmara (MR) regions of the country. In fall, high daily temperatures and cloudless days in CAR and MeR regions are seen under deep surface low over continental Europe and surface high over Caspian Sea, which result in severe dryness events and associated high PM10 values in the air quality stations. On the other hand, as a consequence of the expanding Asiatic monsoon low to the eastern part of Turkey, significant amount of moisture is transferred from the Eastern Mediterranean Sea surface to the CAR and MeR regions by southerly flows (wetness SPEI conditions in fall) and cause to appear below‐normal PM10 values in the southern stations. [ABSTRACT FROM AUTHOR]

In order to figure out the associated underlying dynamical processes of the 2014–2015 warming event, we used the ECCO (Estimating the Circulation and Climate of the Ocean) reanalysis from 1993 to 2016 and two combined scatterometers, QuikSCAT and ASCAT, to analysis hydrodynamic condition and ocean heat budget balance process in the equatorial tropical pacific. The spatiotemporal characteristics of that warming event were revealed by comparing the results with a composite El Niño. The results showed that the significant differences between the 2014 and 2015 warming periods were the magnitudes and positions of the equatorial easterly wind anomalies during the summer months. The abruptly easterly wind anomalies of 2014 that spread across the entire equatorial Pacific triggered the upwelling of the equatorial Kelvin waves and pushed the eastern edge of the warm pool back westward. These combined effects caused abrupt decreases in the sea surface temperatures (SST) and upper ocean heat content (OHC) and damped the 2014 warming process into an El Niño. In addition, the ocean budget of the upper 300 m of the El Niño 3.4 region showed that different dynamical processes were responsible for different warming phases. For example, at the beginning of 2014 and 2015, the U advection and subsurface processes played dominant roles in the positive ocean heat content tendency. During the easterly wind anomalies period of 2014, the U advection process mainly caused a negative tendency and halted the development of the warming phase. In regard to the easterly wind anomalies of 2015, the U advection and subsurface processes were weaker negatively when compared with that in 2014. However, the V advection processes were consistently positive, taking a leading role in the positive trends observed in the middle of 2015. [ABSTRACT FROM AUTHOR]

Copyright of Plateau Meteorology is the property of Plateau Meteorology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The global impacts of El Niño on precipitation have been long‐recognized, but more understanding of the mechanisms behind this influence is needed. For instance, previous studies have largely overlooked the potential impacts of El Niño on terrestrial moisture recycling (TMR). We perform a 40‐year forward tracking simulation to derive a global climatology of recycled precipitation and use a composite analysis to investigate how El Niño affects TMR. We identify seven regions where the El Niño impact on TMR is most significant and find that, in these regions, changes in precipitation and TMR are directly related: they increase or decrease together. In addition, we find a marked latitudinal contrast between the Southern Hemisphere, where TMR increases during El Niño, and the Northern Hemisphere and the tropics, where it decreases. Our results indicate that the weakening and strengthening of TMR can be behind precipitation changes caused by El Niño globally. Plain Language Summary: El Niño is recognized as a climate variability phenomenon with significant impacts on precipitation worldwide. However, the mechanisms behind these impacts are not fully understood. Here we use model simulations to argue that one of those mechanisms is the effect of El Niño on terrestrial moisture recycling (TMR), that is, the fraction of precipitation fed by atmospheric moisture originating not in the ocean but on the continents. We show that El Niño significantly affects TMR globally, especially in seven regions of South America, Africa, North America, Europe, and Asia. In these regions, precipitation and TMR increase or decrease together. We find a contrast between the South and North of the planet: during El Niño, TMR increases in the Southern Hemisphere while decreasing in the Northern Hemisphere and the tropics. Overall, our results indicate that TMR weakening or strengthening are previously overlooked mechanisms behind precipitation changes caused by El Niño globally. Key Points: El Niño exerts significant effects on terrestrial moisture recycling worldwideEl Niño's impacts on terrestrial moisture recycling are most significant in seven regions worldwidePrecipitation and terrestrial moisture recycling increase or decrease together due to El Niño [ABSTRACT FROM AUTHOR]

Study region: The natural river basins of Chile. Study focus: Drought effects on terrestrial ecosystems produce hydroclimatic stress with variable extensions. Particularly, hydrological drought duration can provide a better understanding of recovery together with catchment characteristics and climatology. This study focuses on the impacts of the multi-year drought experienced in Chile for more than a decade.The recovery of relevant catchment variables to quantify the drought termination (DT) and drought termination duration (DTD) after the hydrological drought is presented. A composite analysis of natural catchments using the CAMELS-CL data set discharge (1988–2020), k-NDVI (2000–2020), and soil moisture (1991–2020) provides the average response of the recovery after severe droughts. New hydrological insights for the region: This study demonstrates that local catchment properties can explain the recovery of studied variables after a hydrological drought.Explanatory variables from CAMELS-CL to derive the DT using random forest regression (RFR) were used with a strong correlation of 0.92, 0.84, and 0.89 for discharge, vegetation productivity, and soil moisture, respectively.The discharge patterns show longer recovery over environments dominated by shrublands with less precipitation and higher temperatures, in central Chile, while higher latitudes with higher vegetation cover, increasing precipitation, and lower temperatures present shorter recovery times. The vegetation productivity shows longer recovery over highly vegetated mountains in central Chile. The soil moisture recovery spatial distribution presented patterns that connect them with the discharge recovery. This work enables the identification of drought vulnerability, which is valuable for managing water resources and ecosystems and is helping to predict drought recovery periods in regions with a lack of observations.

Substantial range, handling and acceleration improvements in high-performance vehicles can be achieved by weight reduction. An important area for weight reduction on a car is the wheels. A novel prototype carbon fibre/epoxy wheel has been developed using a combination of automated fibre placement (AFP) and hand layup for the Sunswift 7 solar car. A three-piece wheel design that utilises each process where best suited has been analysed and optimised using the ANSYS ACP PrepPost suite, manufactured, and mechanically tested. The wheel disc was produced using AFP and featured selective reinforcement in the form of spokes. The AFP fibre paths for the disc have been optimised using CGTech's VERICUT VCP and VCS to minimise gaps and overlaps, resulting in a 98.9% reduction in overlaps when compared with the unoptimised layup. The rim and tyre mounting region of the wheel have been manufactured using hand layup and adhesively bonded to the disc. This hybrid manufacturing approach has demonstrated an advancement in the feasibility of combining traditional and automated composite manufacturing. The final wheel weighed 3352 g, and the wheel deflection under a compressive load has been experimentally verified within 3% of the theoretical value. [ABSTRACT FROM AUTHOR]

The total column ozone (TCO) at northern high latitudes is increased over a course of 1–2 months after a major sudden stratospheric warming as a consequence of enhanced ozone eddy transport and diffusive ozone fluxes. We analyzed ground-based measurements of TCO from Oslo, Andøya and Ny Ålesund from 2000 to 2020. During this time interval, 15 major sudden stratospheric warmings (SSWs) occurred. The observed TCO variations are in a good agreement with those of ECMWF Reanalysis v5 (ERA5), showing that TCO from ERA5 is reliable, even during dynamically active periods. ERA5 has the advantage that it has no data gaps during the polar night. We found that TCO was increased by up to 190 DU after the SSW of February 2010, over one month. The composite analysis of the 15 SSWs provided the result that TCO is increased on average by about 50 DU over one month after the central date of the SSW. [ABSTRACT FROM AUTHOR]

Based on the hourly precipitation data at 176 observational stations over south China and the hourly ERA5 reanalysis data during the 40-yr period of 1981-2020, we analyzed the universal characteristics of moisture transport and their associated background circulations for four types of regional extreme precipitation events (REPEs) over south China. Main findings are shown as follow. (i) The wind that transported moisture for the REPEs over south China featured a notable diurnal variation, which was consistent with the variations of the precipitation. (ii) Four types of REPEs could be determined, among which the southwest type (SWT) and the southeast type (SET) accounted for ~92% and ~5.7%, respectively, ranking the first and second, respectively. (iii) Trajectory analyses showed that the air particles of the SWT-REPEs had the largest specific humidity and experienced the most intense ascending motion, and therefore their precipitation was the strongest among the four types. (iv) South China was dominated by notable moisture flux convergence for the four types of REPEs, but their moisture transport was controlled by different flow paths. (v) Composite analyses indicated that the background circulation of the four types of REPEs showed different features, particularly for the intensity, location and coverage of a western Pacific subtropical high. For the SWT-REPEs, their moisture transport was mainly driven by a lower-tropospheric strong southwesterly wind band in the low-latitude regions. Air particles for this type of REPEs mainly passed over the Indochina Peninsula and South China Sea. For the SET-REPEs, their moisture transport was mainly steered by a strong low-tropospheric southeasterly wind northeast of a transversal trough. Air particles mainly passed over the South China Sea for this type of REPEs. [ABSTRACT FROM AUTHOR]

Based on the hourly rainfall data and other conventional data from 52 surface weather stations， and the National Centers for Environmental Prediction （NCEP） Final Analysis （FNL） data， the synoptic circulation patterns for the short-time heavy rainfall over the Qinghai Plateau are classified into three categories， namely the westerly airflow pattern， the subtropical high pattern， and the plateau low vortex-shear line pattern.Results show that the short-time heavy rainfall over the Qinghai Plateau occurs in the area east of 95°E， with the center in the southeast of the plateau.It mainly occurs from May to September， with the maximum in August， followed by July.For the diurnal variation， the short-time heavy rainfall occurs most from 17:00 to 22:00 （Beijing Time）， i.e.， the nightfall to midnight.The influence systems of the westerly airflow pattern are the high-level trough and the straight westerly short-wave trough.The dynamical instability caused by the vertical wind shear induces the short-time heavy rainfall.For the subtropical high pattern， the thermal instability caused by the low-level southerly or easterly warm-humid airflows results in the short-time heavy rainfall.For the plateau low vortex-shear line pattern， the plateau heating， and the weak cold airflow strenthen the low-level frontal area and trigger the short-time heavy rainfall.The composite analysis shows that the South Asian high， the subtropical westerly jet in the upper troposphere， the short-wave trough in the middle-lower troposphere， the shear line， the southerly warm-humid airflow， and the plateau heating field are the main influence systems for the short-time heavy rainfall.The convergence of water vapor from the Indian monsoon， the southeast of the western Pacific subtropical high and the northwest of the westerly trough is conducive to the short-time heavy rainfall in eastern Qinghai.

Composites were manufactured from glass fiber, bagasse fly ash, and epoxy matrix and examined their mechanical and physical properties. The percentages of bagasse fine ash, glass fiber, and matrix were designed at 10%, 15%, 20%, 25%, and 30% with 30% glass fiber and conducted density, flexural strength, hardness, absorption of water, and swelling properties of thickness. Composites were prepared by manual layering. ASTM standards were followed in preparing the samples. According to the results, the bagasse fine ash percentage variation was significant in the composite but had no linear effects on its hardness and flexural strength. A 20% bagasse fine ash composite had the highest flexural strength and hardness at 27.65 MPa and 52.86 HRA, respectively, which are significantly (>0.002) higher than composites of 30% bagasse fine ash, along with the highest density. This study measured water absorption and swelling of composite samples immersed in distilled water for 192 h. As the bagasse ash content increases, these values were linearly increased until saturation occurs. [ABSTRACT FROM AUTHOR]

According to a 10-year (from 2007 to 2016) statistical analysis on the tornadoes in China, Jiangsu Province and Zhejiang Province, which share many similar geographical characteristics, experienced 159 (ranked first) and 59 (ranked fifth) tornadoes, respectively. Tornadoes within Jiangsu [i.e., the Jiangsu type (JST)] and those within Zhejiang [i.e., the Zhejiang type (ZJT)] featured notable annual, monthly and diurnal variations, which were remarkably different from each other. Both JST and ZJT showed the largest occurrence frequency (~50% on average) in the afternoon of summer, and the background environments before the formation of these tornadoes were composited to focus on their respective universal features. For the JST, it is found that, the upper-tropospheric divergence and positive geopotential-height anomaly, the middle-tropospheric shortwave trough, warm temperature advection and positive temperature anomaly, and the lower-tropospheric strong southwesterly wind, convergence and cyclonic vorticity all acted as favorable conditions for the convective activities within Jiangsu. For the ZJT, their background environment differed from that of the Jiangsu notably, and the conditions for the tornadoes' formation were overall more favorable for the JST. Linear trend analyses indicated that, both the annual and seasonal (summer) occurrence of the JST tended to decrease significantly, whereas, those of the ZJT were not significant. For the JST, its occurrence frequency showed a low linear correlation to the variation of the surface temperature, instead, its decreasing frequency was more closely related to the significant weakening in the intensity of the vertical shear of the zonal wind and the updraft helicity within Jiangsu. [ABSTRACT FROM AUTHOR]

Copyright of Arid Zone Research / Ganhanqu Yanjiu is the property of Arid Zone Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study reexamines the correlation between the size and intensity of tropical cyclones (TCs) over the western North Pacific from the perspective of individual TCs, rather than the previous large-sample framework mixing up all TC records. Statistics show that the positive size-intensity correlation based on individual TCs is relatively high. However, this correlation is obscured by mixing large samples. The weakened correlation based on all TC records is primarily due to the diversity in the size change relative to the same intensity change among TCs, which can be quantitatively measured by the linear regression coefficient (RC) of size against intensity. To further explore the factors that cause the variability in RCs that weakens the size-intensity correlation when considering all TC records, the TCs from 2001 to 2020 are classified into two groups according to their RC magnitudes, within which the high-RC TCs have a larger size expansion than the low-RC TCs given the same intensity change. Two key mechanisms responsible for the RC differences are proposed. First, the high-RC TCs are generally located at higher latitudes than the low-RC TCs, resulting in higher planetary vorticity and thus higher planetary angular momentum import at low levels. Second, the high-RC TCs are susceptible to stronger environmental vertical wind shear, leading to more prolific outer convection than the low-RC TCs. The positive feedback between outer diabatic heating and boundary layer inflow favors the inward import of absolute angular momentum in the outer region, thereby contributing to a larger size expansion in the high-RC TCs. [ABSTRACT FROM AUTHOR]

The present study used composite analysis and rainy season definition to investigate rainfall patterns in The Gambia from 1981 to 2020. Rainfall dataset as observed by 10 meteorological stations scattered across The Gambia was used. Results showed that the highest single month rainfall ever recorded in The Gambia during the study period was observed in Sapu, in the eastern sector of the country. The station recorded a total rainfall amount of 767 mm in August, 1999, while the lowest single month rainfall ever recorded was 463 mm in September 2012. It was observed in Jenoi, a station situated in the western sector of the country. Climatological results showed that the study area experienced monomodal rainfall regime during the West African Monsoon, and that the southern part of the western sector region such as Sibanor tend to receive more rainfall compared to other regions of the study area. Part of the central region receives the least annual rainfall. The eastern sector of The Gambia received much of its rain from May to October with July - September as the peak of the rain season. During May - October, Sapu received the heaviest rainfall while Fatoto received the least amount. Results also show that July - September is the period when significant amounts of rainfall are received over the eastern sector of the study area. While May and October are both transitional months, the eastern sector of the study area receives more rains in October than in May. The western sector of the study area, on the other hand, received much of its rain from June to October with July - September as the peak of the rain season. During June - October, Sibanor received the heaviest rainfall while Jenoi received the least amount. The results also show that July - September is the period when significant amounts of rainfall are received over the western sector of the study area. Although June and October are both transitional months, the western sector receives more or less the same rain amounts in June and October. Results further found that, to avert losses associated with excess or deficit in crop water requirement, in the eastern sector, crops with high water requirement should be grown before August as maximum rainfall is observed in August, whereas crops with minimum water requirement should be grown in May or October, that is when minimum rainfall is experienced. In the western sector, on the other hand, crops requiring high water amount should be grown before August or September when maximum rainfall is recorded in the sector, whereas crops with minimum water requirement should be grown in June or October. This study will help create awareness on the erratic rain seasons due to Climate Change, and to provide farmers with information on rainfall distribution in The Gambia to avert losses and impacts associated with water deficit or excess on society, agriculture, and the environment.

This study performs a comprehensive analysis of the influence of low-frequency variability modes (LFVMs) on the average and extreme temperature and precipitation in the extended winter (November–February) over Northwestern North America (NWNA). Maximum covariance analysis is applied to quantify the covariability between LFVMs and regional climate variables, followed by composite analysis to assess the influence of each LFVM on extremes at local scales using high-resolution gridded observations. This study extends previous analyses by characterizing the spatial patterns of regional climate variations associated with a suite of LFVMs. This includes the associations between negative phases of North Atlantic Oscillation (NAO) and extreme precipitation over western NWNA and the central Columbia basin and the positive phase of the North Tropical Atlantic (NTA) with increases in the minimum and maximum temperature of NWNA except for the western Fraser basin. Overall, the analyses show that LFVM effects are more pronounced over the eastern and southcentral parts of NWNA during extended winter. [ABSTRACT FROM AUTHOR]

As wind‐borne migration of insects is strongly influenced by atmospheric circulation and weather systems, the relationships between insect population abundance and meteorological conditions are substantial. The brown planthopper (BPH), Nilaparvata lugens (Stål), is one of the major wind‐borne insects hampering rice production in Asia, and its migration is significantly influenced by the Asian monsoon, a main component of the Asian climate system. However, the degree and mechanisms of the effects of monsoon on BPH migration have been little studied. In this paper, the effect of the Asian monsoon on the northward migration of BPH from the Indochina Peninsula to northern South China (NSC) was investigated based on the BPH light‐trap data and meteorological data for 39 years. The results show that the level of BPH migration in May could indicate the degree of annual pest outbreaks in NSC and that the southeast monsoon was more critical in this northward migration than the previously recognized southwest monsoon. The significance of the southeast monsoon stemmed from the strong effect of South China Sea subtropical high on BPH migration under a unique weather system distribution, the Polar low–Continental low–West Pacific subtropical high pattern. Furthermore, based on the key areas of migration obtained from the composite analysis, the multivariable linear regression prediction model could effectively predict the occurrence of BPH in NSC. These results indicate the importance of interactions between monsoons during BPH northward migration, which reflects the complex relationship between BPH migration and atmospheric motion. [ABSTRACT FROM AUTHOR]

Characteristics of marine heatwaves (MHWs) in the East Asian Marginal Seas (EAMS) were investigated using the daily Optimum Interpolation Sea Surface Temperature for 37 years (1982–2018), focusing on seasonal changes and regional differences. The summer MHWs occur 54% more frequently (2.7 events/decade) in a relatively wide area than in other seasons. The strong (up to 3.7 °C) and long-lasting (up to 38 days/event) winter MHWs are concentrated along the subpolar front (SPF) in the East/Japan Sea (EJS) where the MHWs are 20% longer (2.2 days/event) than in the Yellow and East China Seas (YECS). The summer MHWs are primarily driven by increased shortwave radiation associated with reduced cloud cover and latent cooling from the weakened wind over the western flank of developing subtropical highs. Driving mechanisms of the winter MHWs differ by region. The YECS MHWs occur mainly due to the atmospheric processes associated with weakening continental highs, while the EJS MHWs are largely driven by the northward shift of the SPF. Although large-scale atmospheric processes primarily drive the summer MHWs occurring in a wide area in the EAMS, our findings suggest that ocean processes can be major contributors to intensified MHW generation in limited areas, especially in winter. [ABSTRACT FROM AUTHOR]

Abstract As wind‐borne migration of insects is strongly influenced by atmospheric circulation and weather systems, the relationships between insect population abundance and meteorological conditions are substantial. The brown planthopper (BPH), Nilaparvata lugens (Stål), is one of the major wind‐borne insects hampering rice production in Asia, and its migration is significantly influenced by the Asian monsoon, a main component of the Asian climate system. However, the degree and mechanisms of the effects of monsoon on BPH migration have been little studied. In this paper, the effect of the Asian monsoon on the northward migration of BPH from the Indochina Peninsula to northern South China (NSC) was investigated based on the BPH light‐trap data and meteorological data for 39 years. The results show that the level of BPH migration in May could indicate the degree of annual pest outbreaks in NSC and that the southeast monsoon was more critical in this northward migration than the previously recognized southwest monsoon. The significance of the southeast monsoon stemmed from the strong effect of South China Sea subtropical high on BPH migration under a unique weather system distribution, the Polar low–Continental low–West Pacific subtropical high pattern. Furthermore, based on the key areas of migration obtained from the composite analysis, the multivariable linear regression prediction model could effectively predict the occurrence of BPH in NSC. These results indicate the importance of interactions between monsoons during BPH northward migration, which reflects the complex relationship between BPH migration and atmospheric motion.

Irregular shapes of atmospheric rivers (ARs) hamper easy AR composite analyses and understandings of AR's moisture transport mechanisms. We develop a method to composite AR‐related variables from a reanalysis data set. By averaging a large number of samples, the three‐dimensional structure and some evolutionary features of a typical North Pacific AR are revealed. An AR is typically located along and in advance of the surface cold front of an extratropical cyclone. A mesoscale secondary circulation is observed in the cross sections of the AR corridor, where both geostrophic and ageostrophic winds make indispensable contributions to the moisture fluxes. Geostrophic moisture advection across the cold front within the Equatorward half of the AR is created by baroclinicity of the system and serves as the primary moisture source for the AR. Moisture fluxes from the warm sector of the cyclone are primarily due to boundary layer ageostrophic winds and are more important within the poleward half of the AR, particularly during the genesis stage. Faster AR movement compared with low‐level winds enables the AR to collect downwind moisture. In an AR‐relative view, this is represented as an easterly flow, consistent with the "feeder‐airstream" concept, and emphasizes the role of local moisture recycling. Moisture transport within the Equatorward half is mostly due to geostrophic advection of the propagating AR‐cyclone couple in an Earth‐relative view. Driven by intensifying geostrophic winds, ARs tend to reach peak moisture transport intensity about 2 days after genesis. Then, reduced moisture level and influxes from lateral boundaries prevent further intensification. Plain Language Summary: Atmospheric rivers (ARs) are "river‐like" plumes of airborne horizontal moisture transport that play a crucial role in atmospheric water cycle. Unlike terrestrial rivers, ARs are highly transient and with constantly changing shapes, making it difficult to summarize their structural and dynamical features using a composite analysis. We attack this problem by straightening the irregular ARs using a two‐dimensional interpolation, thus allowing us to create composites from a large number of AR samples. The results reveal the typical structure of a North Pacific AR, its relationship with an accompanying cyclone, the manner in which AR collects moisture from its lateral boundaries, and the changes in different contributing factors following its lifetime evolution. Thanks to its faster propagation speed compared with low‐level winds, an AR collects downwind atmospheric moisture on its poleward‐facing half, a mechanism that is particularly important during its early development stage. The large‐scale circulation associated with the accompanying cyclone accounts for most of the vapor plumes toward the Equatorward‐facing half of the AR. Key Points: Develops a new method to composite atmospheric rivers with irregular shapes and orientationsReveals the meso‐scale secondary circulation across an atmospheric river and highlights the relationship with frontogenesis processesDepicts the 3D structure of moisture transport within an atmospheric river and different geostrophic and ageostrophic contributions [ABSTRACT FROM AUTHOR]

In this study, we investigate the characteristics of atmospheric parameters before, during, and after rain events in Bern, Switzerland. Ground-based microwave radiometer data of the TROpospheric WAter RAdiometer (TROWARA) with a time resolution of 7 s, observations of a weather station, and the composite analysis method are used to derive the temporal evolution of rain events and to identify possible rainfall precursors during a 10-year period (1199 available rain events). A rainfall climatology is developed using parameters integrated water vapor (IWV), integrated liquid water (ILW), rain rate, infrared brightness temperature (T IR ), temperature, pressure, relative humidity, wind speed, and air density. It was found that the IWV is reduced by about 2.2 mm at the end of rain compared to the beginning. IWV and T IR rapidly increase to a peak at the onset of the rainfall. Precursors of rainfall are that the temperature reaches its maximum around 30 to 60 min before rain, while the pressure and relative humidity are minimal. IWV fluctuates the most before rain (obtained with a 10 min bandpass). In 60% of rain events, the air density decreases 2 to 6 h before the onset of rain. The seasonality and the duration of rain events as well as the diurnal cycle of atmospheric parameters are also considered. Thus, a prediction of rainfall is possible with a true detection rate of 60% by using the air density as a precursor. Further improvements in the nowcasting of rainfall are possible by using a combination of various atmospheric parameters which are monitored by a weather station and a ground-based microwave radiometer. [ABSTRACT FROM AUTHOR]

For the plasma generated as a stationary wave in a vacuum vessel, the propagation velocity of the plasma was derived by a simple composite analysis consisting of a plasma emission image and a time fluctuation of the plasma current. The propagation wavelength of the plasma was derived from the shading interval length of the plasma emission intensity obtained by the digital camera in the visual analysis, and the propagation frequency of the plasma was derived from the time variation of the plasma current measured by a current probe in the electrical analysis. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In the recent few decades, climate variability had severely affected the socio-economic and environmental conditions worldwide. Frequent shifts in the atmospheric circulation patterns affect large parts of the globe, predominantly the arid and semi-arid regions facing severe to moderate droughts. Therefore, precursors of drought events and their associated mechanisms are important to understand. This study explores the possible cycles and precursor conditions that might be employed for predicting upcoming droughts in Pakistan. Standardize precipitation index and the single Z-index are used to detect and rank the drought years. Moreover, composite analysis is carried out to explore the large-scale circulation anomalies related to extreme drought events. Results demonstrate that extreme drought events are highly correlated with wind patterns and intrinsic weather system in the Pacific and Indian Oceans. This study analyzed air temperature, sea level pressure and geopotential height in the average time-period of January to March, sea surface temperature from October to December, and wind vectors in March to May as precursors that could be employed to predict the occurrence of droughts in Pakistan. This information is of significance for policymakers to plan climate change adaptive measures accordingly.

The synoptic precipitation variability over Central Africa (CA) in the March-to-May (MAM) and September-to-November (SON) seasons is investigated in this study. The composite analysis is used to highlight the evolution of synoptic precipitation, related convection, and dynamic fields. Composite analysis findings show that synoptic precipitation anomalies increase/fade with an increase/decrease in convection, with the largest amplitude over 5° S–10° N and 2.5–20° E in MAM and 5° N–7.5° N and 5–15° E in SON. Precipitation anomalies and convection associated with the synoptic variability progress eastward preceded (followed) by eastward (westward) low-level wind. This synoptic sequence is associated with a downward motion and an inflow, indicating the storm's presence, which contributes significantly to precipitation initiation over CA. The empirical orthogonal function for precipitation during the SON season is lower than that observed during the MAM season in the context of the size and spatial pattern. During these precipitation occurrences, the zonal moisture component contributes the most to the moisture initiation over the region. The findings of this study show that the observed convergence/divergence position remains unchanged in intensity irrespective of the positive/negative precipitation events. Overall, the synoptic-scale conditions in MAM contribute around 58% of the total variability in precipitation. [ABSTRACT FROM AUTHOR]

Copyright of Plateau Meteorology is the property of Plateau Meteorology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Based on NCEP/FNL, surface observation and upper-air sounding data, and entries of the Southwest China Vortexes(SCVs) Yearbook, we analyzed the activities of Southwest China Vortexes with different vortex sources from 2012 to 2017. Composite and comparative analyses are conducted to the respective wind and other composite physical fields for the characteristics of Jiulong vortex, basin vortex and Xiaojin vortex prior and during the generation phase in the most frequent occurrence time of the year. The effects of background wind, cold and warm air flows, and frontogenesis on the generation of Jiulong vortex, basin vortex and Xiaojin vortex are then obtained. Results are as follows. (1) The main generation and moving period of SCV is from March to June. Jiulong vortex has the main role in SCV, followed by basin vortex. Xiaojing vortex is the least but has the biggest chance to move out of the source. (2) The formation of the Jiulong Vortex and the Xiaojin Vortex is related to the open shape topography of the southwest airflow flowing into their respective vortexes and the wind in Xiaojing vortex is stronger. The formation of the basin vortexes is related to the shear line. (3) The formation of Jiulong vortex and Xiaojin vortex is also related to the positive non-thermal wind vorticity in the warm advection area due to the influence of surface heating and southwest airflow on the leeward slope of the Plateau. However, the warm advection area of Jiulong vortex is larger than that of Xiaojin vortex, and its intensity is much lower than that of Xiaojin vortex. The formation of basin vortex is related to the stronger baroclinic effect of the cold air. (4) The formation of Jiulong vortex, Xiaojin vortex and basin vortex is all related to the enhancement of frontogenesis intensity of the respective vortex sources. But the factors influencing frontogenesis are different. The generation of Xiaojin vortex is mainly affected by the non-adiabatic pro?cess, and the formation of Jiulong vortex is mainly affected by the non-adiabatic change process, together with the horizontal and vertical motion of the airflow. The basin vortex generation is mainly affected by the vertical motion and the non-adiabatic also has some impact on it.

Based on geographical distribution, the North China cold vortexes are divided into three categories:Northeast China Cold Vortex (120°-145°E, 35°-60°N), North China Cold Vortex (100°-130°E, 30°-45°N) and East Mongolia Cold Vortex (100°-130°E, 40°-55°N). According to NCEP/NCAR 1°×1° reanalysis datasets and daily precipitation datasets from 2000 to 2018, the cold vortex cases in 19 years are screened, the activity rules of the three kinds of cold vortexes are statistically analyzed, and the structure and precipitation characteristics of the three kinds of cold vortexes are analyzed by dynamic composite analysis method. The results show that in the 490 cases of high-altitude cold vortexes in 19 years, 2 cases are missed, and 13 cases are repeated. The remaining 475 cases can be well selected and classified, and the definitions of three types of cold vortexes are reasonable. Northeast Cold Vortex and East Mongolian Cold Vortex can occur throughout the year, while North China Cold Vortexes are not found in December and February. Northeast Cold Vortexes are found mostly in April and May, and also in March and August with less frequency. North China cold vortexes are found mostly in May and less frequently in winter. In May, June and September, there are more cold vortexes generated in east Mongolia, while there are fewer in February, March and November. Dynamic composite analysis is used to analyze the three types of cold vortices. In terms of structure, the distribution of potential height, temperature, vorticity, and isentropic potential vortices show that the average strength of the Northeast China Cold Vortex is the strongest, followed by the East Mongolia Cold Vortex, and the North China Cold Vortex is the weakest. In the period when the cold vortex intensity is the strongest, the cold vortex precipitation mainly appears in the north of the outlet area of the upper jet, with strong divergence. Due to the differences in the distribution of low-layer humidity and the intensity of moisture transport, there are differences in the location of large precipitation centers of the three types of cold vortexes. The North China Cold Vortex has the largest mean precipitation intensity, followed by the Northeast Cold Vortex, and the East Mongolia Cold Vortex has relatively weak precipitation.

Copyright of Atmosphere -- Ocean (Taylor & Francis Ltd) is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)