Atmosphere

Editorial

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4 pages, 202 KiB

Open AccessEditorial

Weather and Climate Extremes: Current Developments

by Anita Drumond, Margarida L. R. Liberato, Michelle S. Reboita and Andréa S. Taschetto

Atmosphere 2020, 11(1), 24; https://doi.org/10.3390/atmos11010024 - 25 Dec 2019

Cited by 5 | Viewed by 2904

Abstract

An increasing number of extreme events have been observed around the world over the past few decades, some of them attributed to global warming [...] Full article

(This article belongs to the Special Issue Weather and Climate Extremes: Current Developments)

Research

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21 pages, 18864 KiB

Open AccessArticle

Numerical Modeling of Meteotsunami–Tide Interaction in the Eastern Yellow Sea

by Ki-Young Heo, Jae-Seon Yoon, Jae-Seok Bae and Taemin Ha

Atmosphere 2019, 10(7), 369; https://doi.org/10.3390/atmos10070369 - 2 Jul 2019

Cited by 4 | Viewed by 3831

Abstract

Meteotsunamis originating from atmospheric pressure disturbances have frequently occurred in oceans worldwide and their destructive long waves have recently threatened local coastal communities. In particular, meteotsunamis occurring in the Yellow Sea caused unexpected casualties and property damage to local communities on the western [...] Read more.

Meteotsunamis originating from atmospheric pressure disturbances have frequently occurred in oceans worldwide and their destructive long waves have recently threatened local coastal communities. In particular, meteotsunamis occurring in the Yellow Sea caused unexpected casualties and property damage to local communities on the western coast of the Korean Peninsula in 2007 and 2008. These events attracted the attention of many engineers and scientists because abrupt extreme waves have struck several coasts and ports even under fine weather conditions. Furthermore, the Yellow Sea has the highest tide and most powerful tidal currents in the world, and consequently, meteotsunami events there could be more destructive and harmful to local coastal communities when such events occur during high tide or a critical phase with strong tidal currents. In this study, numerical experiments were conducted to identify the qualitative effect of the interaction between a meteotsunami and the tide on the generation and amplification mechanisms of meteotsunamis occurring in the Yellow Sea. In general, small-scale meteotsunamis, such as those that occur in the Yellow Sea, should be analyzed using a high-resolution modeling system because water motions can be affected by local terrain. To achieve this objective, high-resolution atmospheric modeling was conducted to reproduce the atmospheric pressure disturbances observed in the Yellow Sea; then, the generation and propagation of the meteotsunami over real topographies was simulated using a phase-resolving wave model. Both an atmospheric model (Weather Research and Forecasting Model (WRF)) and a shallow water equation model (COrnell Multigrid COupled Tsunami Model (COMCOT)) were employed to simulate the generation and transformation of the meteotsunami. Full article

(This article belongs to the Special Issue Weather and Climate Extremes: Current Developments)

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19 pages, 7968 KiB

Open AccessArticle

Explosive Cyclogenesis around the Korean Peninsula in May 2016 from a Potential Vorticity Perspective: Case Study and Numerical Simulations

by Ki-Young Heo, Kyung-Ja Ha and Taemin Ha

Atmosphere 2019, 10(6), 322; https://doi.org/10.3390/atmos10060322 - 12 Jun 2019

Cited by 8 | Viewed by 5244

Abstract

An explosive cyclone event that occurred near the Korean Peninsula in early May 2016 is simulated using the Weather Research and Forecasting (WRF) model to examine the developmental mechanisms of the explosive cyclone. After confirming that the WRF model reproduces the synoptic environments [...] Read more.

An explosive cyclone event that occurred near the Korean Peninsula in early May 2016 is simulated using the Weather Research and Forecasting (WRF) model to examine the developmental mechanisms of the explosive cyclone. After confirming that the WRF model reproduces the synoptic environments and main features of the event well, the favorable environmental conditions for the rapid development of the cyclone are analyzed, and the explosive development mechanisms of the cyclone are investigated with perturbation potential vorticity (PV) fields. The piecewise PV inversion method is used to identify the dynamically relevant meteorological fields associated with each perturbation PV anomaly. The rapid deepening of the surface cyclone was influenced by both adiabatic (an upper tropospheric PV anomaly) and diabatic (a low-level PV anomaly associated with condensational heating) processes, while the baroclinic processes in the lower troposphere had the smallest contribution. In the explosive phase of the cyclone life cycle, the diabatically generated PV anomalies associated with condensational heating induced by the ascending air in the warm conveyor belt are the most important factors for the initial intensity of the cyclone. The upper-level forcing is the most important factor in the evolution of the cyclone’s track, but it is of secondary importance for the initial strong deepening. Full article

(This article belongs to the Special Issue Weather and Climate Extremes: Current Developments)

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15 pages, 3518 KiB

Open AccessArticle

Characterization and Spatial Coverage of Heat Waves in Subtropical Brazil

by Nicolle Cordero Simões dos Reis, Nathalie Tissot Boiaski and Simone Erotildes Teleginski Ferraz

Atmosphere 2019, 10(5), 284; https://doi.org/10.3390/atmos10050284 - 21 May 2019

Cited by 17 | Viewed by 3975

Abstract

Given the increase in the frequency, intensity, and persistence of heat waves since the 1970s, and in view of the impacts that extreme temperatures may cause for society and the economy, this study aims to characterize heat waves in the subtropical region of [...] Read more.

Given the increase in the frequency, intensity, and persistence of heat waves since the 1970s, and in view of the impacts that extreme temperatures may cause for society and the economy, this study aims to characterize heat waves in the subtropical region of Brazil and compare findings with the criterion defined by the World Meteorological Organization (WMO). Daily maximum temperature data was used. By using the percentile methodology, the subtropical region was divided into two regions: region 1 and region 2. We identified 54 heat waves in region 1 and 34 in region 2, which occurred more frequently in winter and spring, and less frequently in summer. A close relationship was observed between the Pacific Decadal Oscillation (PDO) and El Niño–Southern Oscillation (ENSO), both of which are able to modulate the heat waves in each of the different regions. Region 1 presented the highest number of heat waves during the warm (cold) phase of the PDO. As for ENSO, heat waves were more frequent in the neutral phase in both regions. Finally, there was shown to be an increase in the frequency and persistence of heat waves since the 1980s, especially in region 2. The methodology used in this study allows the identification and characterization of heat waves in several regions of different climates. Full article

(This article belongs to the Special Issue Weather and Climate Extremes: Current Developments)

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19 pages, 6340 KiB

Open AccessArticle

Optimization of Parameters in the Generalized Extreme-Value Distribution Type 1 for Three Populations Using Harmonic Search

by Juan Pablo Molina-Aguilar, Alfonso Gutierrez-Lopez, Jose Angel Raynal-Villaseñor and Luis Gabriel Garcia-Valenzuela

Atmosphere 2019, 10(5), 257; https://doi.org/10.3390/atmos10050257 - 9 May 2019

Cited by 6 | Viewed by 3158

Abstract

Due to its geographical position, Mexico is exposed annually to cold fronts and tropical cyclones, registering extremely high values that are atypical in the series of maximum annual flows. Univariate mixed probability distribution functions have been developed based on the theory of extreme [...] Read more.

Due to its geographical position, Mexico is exposed annually to cold fronts and tropical cyclones, registering extremely high values that are atypical in the series of maximum annual flows. Univariate mixed probability distribution functions have been developed based on the theory of extreme values, which require techniques to determine their parameters. Therefore, this paper explores a function that considers three populations to analyze maximum annual flows. According to the structure of the Generalized Extreme-Value Distribution (GEV), the simultaneous definition of nine parameters is required: three of location, three of scale, and three of probability of occurrence. Thus, the use of a meta-heuristic technique was proposed (harmonic search). The precision of the adjustment was increased through the optimization of the parameters, and with it came a reduction in the uncertainty of the forecast, particularly for cyclonic events. It is concluded that the use of an extreme value distribution (Type I) structured with three populations and accompanied by the technique of harmonic search improves the performance in respect to classic techniques for the determination of its parameters. Full article

(This article belongs to the Special Issue Weather and Climate Extremes: Current Developments)

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15 pages, 3264 KiB

Open AccessArticle

Variability of Summer Precipitation Events Associated with Tropical Cyclones over Mid-Lower Reaches of Yangtze River Basin: Role of the El Niño–Southern Oscillation

by Fuqiang Cao, Tao Gao, Li Dan, Lian Xie and Xiang Gong

Atmosphere 2019, 10(5), 256; https://doi.org/10.3390/atmos10050256 - 9 May 2019

Cited by 8 | Viewed by 2745

Abstract

Based on tropical cyclone (TC) track data and gridded observational rainfall data of CN05.1 during the period of 1961 to 2014, we examine the contribution of TCs on three metrics of summertime rainfall regimes and identify the connection between TC-induced precipitation events and [...] Read more.

Based on tropical cyclone (TC) track data and gridded observational rainfall data of CN05.1 during the period of 1961 to 2014, we examine the contribution of TCs on three metrics of summertime rainfall regimes and identify the connection between TC-induced precipitation events and El Niño–Southern Oscillation (ENSO) in middle–lower reaches of Yangtze River Basin (MLYRB). At the regional scale, TCs are responsible for approximately 14.4%, 12.5%, and 6.9% of rainfall events for normal, 75th, and 95th percentile precipitation cases, respectively. There is no evidence of significant long-term trends of the three type events linked with TCs, while their interdecadal variability is remarkable. Fractionally, larger proportions of TC-induced events occur along southeast coastal regions of MLYRB for normal rainfall events, and they are recorded over southwest and central-east MLYRB for 95th percentile cases. Moreover, a larger contribution of 95th percentile precipitation events to summer total rainfall is found than that for 75th percentile cases, suggesting that TCs may exert stronger impacts on the upper tail of summertime precipitation distribution across MLYRB. The TC-induced normal rainfall events tend to occur more frequency over central-west MLYRB during negative phase of ENSO in summer. However, the higher likelihood of TC-induced rainfall for three defined metrics are found over the majority of areas over MLYRB during negative ENSO phase in spring. In preceding winter, La Niña episode plays a crucial role in controlling the frequency of both normal and 75th percentile precipitation events. Full article

(This article belongs to the Special Issue Weather and Climate Extremes: Current Developments)

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21 pages, 24708 KiB

Open AccessArticle

Trend Analysis of Temperature and Precipitation Extremes during Winter Wheat Growth Period in the Major Winter Wheat Planting Area of China

by Hanjiang Nie, Tianling Qin, Hanbo Yang, Juan Chen, Shan He, Zhenyu Lv and Zhenqian Shen

Atmosphere 2019, 10(5), 240; https://doi.org/10.3390/atmos10050240 - 1 May 2019

Cited by 20 | Viewed by 4761

Abstract

In this study, the major winter wheat planting area of China is selected as the study area, with the time scale of the growth period of winter wheat (a total of 56 growth periods during October 1961 to May 2016). The significance, stability, [...] Read more.

In this study, the major winter wheat planting area of China is selected as the study area, with the time scale of the growth period of winter wheat (a total of 56 growth periods during October 1961 to May 2016). The significance, stability, magnitude of the trend and the average trend of the study area with eight temperature indices and seven precipitation indices of 453 meteorological stations are tested by Mann–Kendall method and Sen’s nonparametric method. The following observation can be made: (1) the cold extreme indices show strong and stable downward trend in most of the stations in the study area, while the hot extreme indices show a strong and stable upward trend, especially in the northern winter wheat planting area and the north of the southern winter wheat planting area. (2) The trends of extreme precipitation indices in most of the sites in the study area are insignificant and unstable. Only in R20mm, a significant and stable decreasing trend is shown in some stations, which is mainly located in the northern winter wheat planting area and part of the central and western regions in the study area. The results in some ways could enrich the references for understanding the climate change in the growth period of winter wheat in the region and help to formulate a better agronomic management practice of winter wheat. Full article

(This article belongs to the Special Issue Weather and Climate Extremes: Current Developments)

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14 pages, 3655 KiB

Open AccessArticle

Changes in Precipitation and Drought Extremes over the Past Half Century in China

by Min Liu, Yanjun Shen, Yongqing Qi, Yanfang Wang and Xinxin Geng

Atmosphere 2019, 10(4), 203; https://doi.org/10.3390/atmos10040203 - 15 Apr 2019

Cited by 24 | Viewed by 4577

Abstract

Changes in climate extremes have become a hot issue in the research field of climate change recently. Many studies have reported that climate extremes have occurred more frequently and with increasing intensity in recent decades. In this study, thresholds of precipitation and drought [...] Read more.

Changes in climate extremes have become a hot issue in the research field of climate change recently. Many studies have reported that climate extremes have occurred more frequently and with increasing intensity in recent decades. In this study, thresholds of precipitation and drought extremes were determined by the cumulative distribution function, and their spatiotemporal changes over the past half-century in China were analyzed by relative change rate. The results show that: (1) precipitation extremes increased in all regions except North China, while increasing trends of drought extremes were detected in all regions except Northwest China and the Qing–Tibet Plateau; (2) the maximum change rates in frequency of precipitation extremes were found in Northwest China and the Qing–Tibet Plateau, with values of 16.13% and 8.12%, and the maximum change rates in frequency of drought extremes were in Southwest and Southeast China, whose increases in intensity of drought extremes were also the maximum; (3) variation in precipitation extremes showed a relatively mixed pattern with higher heterogeneity compared to that of drought extremes; and (4) changes in precipitation and drought extremes relate to mid-intensity, lower-intensity, and annual precipitation. Full article

(This article belongs to the Special Issue Weather and Climate Extremes: Current Developments)

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16 pages, 7128 KiB

Open AccessArticle

Climatology and Trend of Severe Drought Events in the State of Sao Paulo, Brazil, during the 20th Century

by Luiz F. Gozzo, Doris S. Palma, Maria S. Custodio and Jeferson P. Machado

Atmosphere 2019, 10(4), 190; https://doi.org/10.3390/atmos10040190 - 9 Apr 2019

Cited by 21 | Viewed by 5278

Abstract

Drought is a natural hazard with critical societal and economic consequences to millions of people around the world. In this paper, we present the climatology of severe drought events that occurred during the 20th century in the region of Sao Paulo, Brazil. To [...] Read more.

Drought is a natural hazard with critical societal and economic consequences to millions of people around the world. In this paper, we present the climatology of severe drought events that occurred during the 20th century in the region of Sao Paulo, Brazil. To account for the effects of rainfall deficit and changes in temperature at a climatic timescale, we chose the Standardized Precipitation Evapotranspiration Index (SPEI) to identify severe droughts over the city of Sao Paulo, and the eastern and central-western regions of the state. Events were identified using weather station data and European Centre for Medium-Range Weather Forecast (ECMWF) reanalysis data, in order to assess the representation of drought periods in both datasets. Results show that the reanalysis seems suitable to represent the number of events and their mean duration, severity and intensity, but the timing and characteristics of individual events are not well reproduced. The correlation between observation and reanalysis SPEI time series is low to moderate in all cases. A linear trend analysis between 1901 and 2010 shows a tendency of increasing (decreasing) severe drought events in the central and western (eastern) Sao Paulo state, according to observational data. This is in agreement with previous findings, and the reanalysis presents this same signal. The weakened trend values in the reanalysis may be associated with issues in representing precipitation in this dataset. Full article

(This article belongs to the Special Issue Weather and Climate Extremes: Current Developments)

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16 pages, 821 KiB

Open AccessArticle

Recurrence Spectra of European Temperature in Historical Climate Simulations

by M. Carmen Alvarez-Castro, Davide Faranda, Thomas Noël and Pascal Yiou

Atmosphere 2019, 10(4), 166; https://doi.org/10.3390/atmos10040166 - 28 Mar 2019

Cited by 3 | Viewed by 3275

Abstract

We analyse and quantify the recurrences of European temperature extremes using 32 historical simulations (1900–1999) of the fifth Coupled Model Intercomparison Project (CMIP5) and 8 historical simulations (1971–2005) from the EUROCORDEX experiment. We compare the former simulations to the 20th Century Reanalysis (20CRv2c) [...] Read more.

We analyse and quantify the recurrences of European temperature extremes using 32 historical simulations (1900–1999) of the fifth Coupled Model Intercomparison Project (CMIP5) and 8 historical simulations (1971–2005) from the EUROCORDEX experiment. We compare the former simulations to the 20th Century Reanalysis (20CRv2c) dataset to compute recurrence spectra of temperature in Europe. We find that, (1) the spectra obtained by the model ensemble mean are generally consistent with those of 20CR; (2) spectra biases have a strong regional dependence; (3) the resolution does not change the order of magnitude of spectral biases between models and reanalysis, (4) the spread in recurrence biases is larger for cold extremes. Our analysis of biases provides a new way of selecting a subset of the CMIP5 ensemble to obtain an optimal estimate of temperature recurrences for a range of time-scales. Full article

(This article belongs to the Special Issue Weather and Climate Extremes: Current Developments)

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15 pages, 12337 KiB

Open AccessArticle

Autumn Cold Surge Paths over North China and the Associated Atmospheric Circulation

by Bo Cai, Gang Zeng, Guwei Zhang and Zhongxian Li

Atmosphere 2019, 10(3), 134; https://doi.org/10.3390/atmos10030134 - 12 Mar 2019

Cited by 17 | Viewed by 3930

Abstract

Using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model, we tracked the paths of 46 autumn cold surges affecting North China from 1961 to 2014, and classified them by clustering analysis, thereby investigating their changes and associated atmospheric circulation evolution. Our results indicate [...] Read more.

Using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model, we tracked the paths of 46 autumn cold surges affecting North China from 1961 to 2014, and classified them by clustering analysis, thereby investigating their changes and associated atmospheric circulation evolution. Our results indicate that autumn cold surges affecting North China can be classified into three types according to their paths: the north type, west type, and northwest type, with occurrences of 12, 16, and 18 respectively. Different types of cold surges have different atmospheric circulation characteristics. The north type is associated with a blocking type of atmospheric circulation pattern, with an enhanced stretching northeast ridge over the Ural Mountains and a transverse trough over Lake Baikal. However, the northwest type is characterized by a ridge–trough–ridge wave-train pattern that is located over the Barents Sea, West Siberian Plain, and Sakhalin Island, respectively. The west-type cold surge is related to a conversion type: a blocking system over the Ural Mountains forms four days before the cold surge occurrence, after which it becomes a wave-train type. The atmospheric signals detected prior to the occurrences of the three types of cold surges are also explored. The main signal of the north-path cold surges is that the energy propagates eastward from the Azores Islands to the Ural Mountains, and then forms a blocking high over the Urals. However, for the northwest-path cold surges, there is a weak trough over the Ural Mountains that gradually strengthens because the blocking high collapses over the Norwegian Sea. The key signal of the formation of the west-path cold surges is a blocking high over the Norwegian Sea’s continuous enhancement and extension to Novaya Zemlya, which results in a transmission of energy to the Ural Mountains and leads to the formation of a blocking system over here. When the above-mentioned different types of atmospheric circulation characteristics appear, the type of cold surge path and its impact area can be potentially forecasted in advance, which may reduce the losses that result from cold surges. Full article

(This article belongs to the Special Issue Weather and Climate Extremes: Current Developments)

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16 pages, 5443 KiB

Open AccessArticle

Extreme Weather Impacts on Inland Waterways Transport of Yangtze River

by Lijun Liu, Yuanqiao Wen, Youjia Liang, Fan Zhang and Tiantian Yang

Atmosphere 2019, 10(3), 133; https://doi.org/10.3390/atmos10030133 - 12 Mar 2019

Cited by 15 | Viewed by 4448

Abstract

The impact of extreme weather events on the navigation environment in the inland waterways of the Yangtze River is an interdisciplinary hotspot in subjects of maritime traffic safety and maritime meteorology, and it is also a difficult point for the implementation of decision-making [...] Read more.

The impact of extreme weather events on the navigation environment in the inland waterways of the Yangtze River is an interdisciplinary hotspot in subjects of maritime traffic safety and maritime meteorology, and it is also a difficult point for the implementation of decision-making and management by maritime and meteorological departments in China. The objective of this study is to review the variation trends and distribution patterns in the periods of adverse and extreme weather events that are expected to impact on inland waterways transport (IWT) on the Yangtze River. The frequency of severe weather events, together with the changes in their spatial extension and intensity, is analyzed based on the ERA-Interim datasets (1979–2017) and the GHCNDEX dataset (1979–2017), as well as the research progresses and important events (2004–2016) affecting the navigation environment. The impacts of extreme weather events on IWT accidents and phenomena of extreme weather (e.g., thunderstorms, lightning, hail, and tornadoes) that affect the navigation environment are also analyzed and discussed. The results show that: (1) the sections located in the plain climate zone is affected by extreme weather in every season, especially strong winds and heat waves; (2) the sections located in the hilly mountain climate zone is affected particularly by spring extreme phenomena, especially heat waves; (3) the sections located in the Sichuan Basin climate zone is dominated by the extreme weather phenomena in autumn, except cold waves; (4) the occurrence frequency of potential flood risk events is relatively high under rainstorm conditions and wind gusts almost affect the navigation environment of the Jiangsu and Shanghai sections in every year; (5) the heat wave indices (TXx, TR, and WSDI) tend to increase and the temperature of the coldest day of the year gradually increases; (6) the high occurrences of IWT accidents need to be emphasized by relevant departments, caused by extreme weather during the dry season; and (7) the trends and the degree of attention of extreme weather events affecting IWT are ranked as: heat wave > heavy rainfall > wind gust > cold spell > storm. Understanding the seasonal and annual frequency of occurrence of extreme weather events has reference significance for regional management of the Yangtze River. Full article

(This article belongs to the Special Issue Weather and Climate Extremes: Current Developments)

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10 pages, 3155 KiB

Open AccessArticle

Spatial and Temporal Variations of Compound Droughts and Hot Extremes in China

by Xinying Wu, Zengchao Hao, Fanghua Hao, Chong Li and Xuan Zhang

Atmosphere 2019, 10(2), 95; https://doi.org/10.3390/atmos10020095 - 21 Feb 2019

Cited by 43 | Viewed by 5265

Abstract

Droughts and hot extremes may lead to tremendous impacts on the ecosystem and different sectors of the society. A variety of studies have been conducted on the variability of the individual drought or hot extreme in China. However, the evaluation of compound droughts [...] Read more.

Droughts and hot extremes may lead to tremendous impacts on the ecosystem and different sectors of the society. A variety of studies have been conducted on the variability of the individual drought or hot extreme in China. However, the evaluation of compound droughts and hot extremes, which may induce even larger impacts than the individual drought or hot extreme, is still lacking. The aim of this study is to investigate changes in the frequency and spatial extent of compound droughts and hot extremes during summer in China using monthly precipitation and daily temperature data from 1953 to 2012. Results show that a high frequency of compound droughts and hot extremes mostly occur in the regions stretching from northeast to southwest of China. There is an overall increase in the frequency of co-occurrence of droughts and hot extremes across most parts of China with distinct regional patterns. In addition, an increasing trend in the areas covered by compound extremes has been observed, especially after the 1990s. At regional scales, the increase of the frequency and spatial extent of compound extremes has been shown to be most profound in North China (NC), South China (SC), and Southwest China (SWC), while the decrease of compound extremes was found in Central China (CC). These results show the variability of compound droughts and hot extremes and could provide useful insights into the mitigation efforts of extreme events in China. Full article

(This article belongs to the Special Issue Weather and Climate Extremes: Current Developments)

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21 pages, 13837 KiB

Open AccessArticle

Key Features and Adverse Weather of the Named Subtropical Cyclones over the Southwestern South Atlantic Ocean

by Michelle Simões Reboita, Rosmeri Porfírio Da Rocha and Débora Martins de Oliveira

Atmosphere 2019, 10(1), 6; https://doi.org/10.3390/atmos10010006 - 27 Dec 2018

Cited by 27 | Viewed by 5748

Abstract

This work documents the main features of six subtropical cyclones occurred between the years 2010 and 2016 over the southwestern South Atlantic Ocean, near the Brazilian coast, which received names (with the exception of one) from the Brazilian Navy Hydrographic Center. The fine-resolution [...] Read more.

This work documents the main features of six subtropical cyclones occurred between the years 2010 and 2016 over the southwestern South Atlantic Ocean, near the Brazilian coast, which received names (with the exception of one) from the Brazilian Navy Hydrographic Center. The fine-resolution ERA5 reanalysis and rainfall estimates from the Tropical Rainfall Measuring Mission (TRMM) were used to describe the synoptic environment and the adverse weather conditions during the six events. The support of a small-amplitude trough at mid-levels or a cut-off low, weak vertical wind shear, and moisture flux convergence are the main features contributing to the subtropical cyclogenesis at the surface. On the other hand, sea surface temperature (SST) presents a secondary contribution since the cyclones develop over the ocean with a wide range of SST values (from 22.5 °C to 28.6 °C in the initial phase of cyclones). The six subtropical cyclones are less deep in the atmosphere column than the tropical ones and, unlike the extratropical cyclones, they have little or no westward tilt with an increase in height. The studied subtropical cyclones produced adverse weather conditions such as (a) strong winds (reaching 17 m·s⁻¹ at 10 m high) for a long period occurring east/southeastward of the cyclone center, and (b) high amounts of rainfall along the southeastern coast of Brazil, where the accumulated rainfall varied between 170 to 350 mm, being in most cases higher than the monthly climatology. Over the continent, the Brazilian states of Rio de Janeiro and Espírito Santo were the most affected by the intense rainfall associated with the cyclones. Full article

(This article belongs to the Special Issue Weather and Climate Extremes: Current Developments)

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17 pages, 9293 KiB

Open AccessArticle

Changes in Extreme Low Temperature Events over Northern China under 1.5 °C and 2.0 °C Warmer Future Scenarios

by Weiwei Hu, Guwei Zhang, Gang Zeng and Zhongxian Li

Atmosphere 2019, 10(1), 1; https://doi.org/10.3390/atmos10010001 - 21 Dec 2018

Cited by 19 | Viewed by 3988

Abstract

Recently, NCAR (the National Center for Atmospheric Research) released the Community Earth System Model’s low-warming simulations, which provided long-term climate data for stabilization pathways at 1.5 °C and 2.0 °C above pre-industrial levels. Based on these data, six extreme low temperature indices—TXn (coldest [...] Read more.

Recently, NCAR (the National Center for Atmospheric Research) released the Community Earth System Model’s low-warming simulations, which provided long-term climate data for stabilization pathways at 1.5 °C and 2.0 °C above pre-industrial levels. Based on these data, six extreme low temperature indices—TXn (coldest day), TNn (coldest night), TX10p (cool days), TN10p (cool nights), CSDI (cold spell duration indicator), and DTR (diurnal temperature range)—were calculated to assess the changes in extreme low temperature over Northern China under 1.5 °C and 2.0 °C warmer future. The results indicate that compared to the preindustrial level, the whole of China will experience 0.32–0.46 °C higher minimum surface air temperature (SAT) warming than the global average, and the winter temperature increase in Northern China will be the most pronounced over the country. In almost all the regions of Northern China, especially Northeast and Northwest China, extreme low temperature events will occur with lower intensity, frequency, and duration. Compared with the present day, the intensity of low temperature events will decrease most in Northeast China, with TXn increasing by 1.9 °C/2.0 °C and TNn increasing by 2.0 °C/2.5 °C under 1.5 °C/2.0 °C global warming, respectively. The frequency of low temperature events will decrease relatively more in North China, with TX10p decreasing by 8 days/11 days and TN10p decreasing by 7 days/9 days under 1.5 °C/2.0 °C warming. CSDI will decrease most in Northwest China, with decreases of 7 days/10 days with 1.5 °C/2.0 °C warming. DTR will decrease in the Northwest and Northeast but increase in North China, with −0.9 °C/−2.0 °C in the Northwest, −0.4 °C/−1.5 °C in the Northeast, and 1.7 °C/2.0 °C in North China in the 1.5 °C/2.0 °C warming scenarios. For temperatures lower than the 5th percentile, the PRs (probability ratios) will be 0.68 and 0.55 of that of the present day under 1.5 °C and 2.0 °C warmer futures, respectively. Global warming of 2.0 °C instead of 1.5 °C will lead to extreme low temperature events decreasing by 6–56% in regard to intensity, frequency, and duration over Northern China, and the maximal values of decrease (24–56%) will be seen in Northeast China. Full article

(This article belongs to the Special Issue Weather and Climate Extremes: Current Developments)

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20 pages, 798 KiB

Open AccessArticle

Local Perceptions of Climate Change Impacts in St. Kitts (Caribbean Sea) and Malé, Maldives (Indian Ocean)

by Charlotte Eloise Stancioff, Robert Stojanov, Ilan Kelman, Daniel Němec, Jaromir Landa, Radomir Tichy, David Prochazka, Graeme Brown and Corinne L. Hofman

Atmosphere 2018, 9(12), 459; https://doi.org/10.3390/atmos9120459 - 22 Nov 2018

Cited by 18 | Viewed by 9859

Abstract

Small Island Developing States (SIDS) are now experiencing the local consequences of a changing climate, environment, and society. Nonetheless, climate change research frequently remains at regional or national levels. Without locally grounded data, islanders’ perceived impacts of the changes might not be considered, [...] Read more.

Small Island Developing States (SIDS) are now experiencing the local consequences of a changing climate, environment, and society. Nonetheless, climate change research frequently remains at regional or national levels. Without locally grounded data, islanders’ perceived impacts of the changes might not be considered, thereby causing difficulties when policy and practice responses are implemented without accounting for local understandings. To contribute to addressing this gap, this study examines perceptions of climate change and associated environmental and social changes in two SIDS case studies: St. Kitts in the Caribbean Sea and Malé Atoll, Maldives in the Indian Ocean. Through these two case studies, we assess perceptions of changing social and natural environments through a closed-question, face-to-face survey. Our results suggest that in both island case studies, communities perceive environmental changes to be happening that demand negotiation with the social changes of daily life. Results also suggest that perceived climate change impacts are only part of the equation, as social and economic impacts reveal two case studies of changing island societies. While the geographic context in each case study differs, this study reveals the perceived impacts of climate change and social changes at a local level, providing valuable insights and angles for formulating policies and actions to deal with the myriad of social and environmental changes affecting SIDS. Full article

(This article belongs to the Special Issue Weather and Climate Extremes: Current Developments)

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19 pages, 16451 KiB

Open AccessArticle

Influence of the Antarctic Oscillation on the South Atlantic Convergence Zone

by Flávia Venturini Rosso, Nathalie Tissot Boiaski, Simone Erotildes Teleginski Ferraz and Tiago Capello Robles

Atmosphere 2018, 9(11), 431; https://doi.org/10.3390/atmos9110431 - 7 Nov 2018

Cited by 22 | Viewed by 5691

Abstract

The South Atlantic convergence zone (SACZ) is the main summer-typical atmospheric phenomenon occurring in South America, and it is of great interest because it regulates the rainy season in the most populated regions of Brazil. Frequency variability, persistence, and geographical position of the [...] Read more.

The South Atlantic convergence zone (SACZ) is the main summer-typical atmospheric phenomenon occurring in South America, and it is of great interest because it regulates the rainy season in the most populated regions of Brazil. Frequency variability, persistence, and geographical position of the SACZ and its relationship with intraseasonal variability is well described in the literature. However, the influence of extratropical forcing on the SACZ is not well understood. Consequently, the aim of this study is to evaluate the role of the Antarctic Oscillation (AAO) in SACZ events. The persistence and frequencies of SACZ events, mean, standard deviation of total precipitation per event, lag composite of daily precipitation and geopotential height anomalies were obtained for each phase of the AAO. Therefore, frequency, persistence and total precipitation of SACZ events were higher in positive AAO (AAO+) than negative AAO (AAO−). A teleconnection mechanism between the extratropics and the SACZ region is evident in AAO+, through intensification of the polar and subtropical jets, in the days preceding SACZ. The same was not observed in the AAO−, where the anomalies were confined in the subtropical region and displaced to the South Atlantic Ocean. Full article

(This article belongs to the Special Issue Weather and Climate Extremes: Current Developments)

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17 pages, 6773 KiB

Open AccessArticle

Tropical Atlantic Response to Last Millennium Volcanic Forcing

by Luciana Figueiredo Prado, Ilana Wainer and Pedro Leite da Silva Dias

Atmosphere 2018, 9(11), 421; https://doi.org/10.3390/atmos9110421 - 27 Oct 2018

Cited by 4 | Viewed by 3208

Abstract

Climate responses to volcanic eruptions include changes in the distribution of temperature and precipitation such as those associated with El Niño Southern Oscillation (ENSO). Recent studies suggest an ENSO-positive phase after a volcanic eruption. In the Atlantic Basin, a similar mode of variability [...] Read more.

Climate responses to volcanic eruptions include changes in the distribution of temperature and precipitation such as those associated with El Niño Southern Oscillation (ENSO). Recent studies suggest an ENSO-positive phase after a volcanic eruption. In the Atlantic Basin, a similar mode of variability is referred as the Atlantic Niño, which is related to precipitation variability in West Africa and South America. Both ENSO and Atlantic Niño are characterized in the tropics by conjoined fluctuations in sea surface temperature (SST), zonal winds, and thermocline depth. Here, we examine possible responses of the Tropical Atlantic to last millennium volcanic forcing via SST, zonal winds, and thermocline changes. We used simulation results from the National Center for Atmospheric Research Community Earth System Model Last Millennium Ensemble single-forcing experiment ranging from 850 to 1850 C.E. Our results show an SST cooling in the Tropical Atlantic during the post-eruption year accompanied by differences in the Atlantic Niño associated feedback. However, we found no significant deviations in zonal winds and thermocline depth related to the volcanic forcing in the first 10 years after the eruption. Changes in South America and Africa monsoon precipitation regimes related to the volcanic forcing were detected, as well as in the Intertropical Convergence Zone position and associated precipitation. These precipitation responses derive primarily from Southern and Tropical volcanic eruptions and occur predominantly during the austral summer and autumn of the post-eruption year. Full article

(This article belongs to the Special Issue Weather and Climate Extremes: Current Developments)

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15 pages, 6580 KiB

Open AccessArticle

Seasonal Changes of Extremes in Isolated and Mesoscale Precipitation for the Southeastern United States

by Thomas Rickenbach

Atmosphere 2018, 9(8), 309; https://doi.org/10.3390/atmos9080309 - 9 Aug 2018

Cited by 6 | Viewed by 3432

Abstract

The association between instantaneous extreme precipitation and mesoscale organization over the southeastern United States is not well known. This study addresses whether isolated precipitation features have a distinct distribution and spatial pattern of extreme rain compared to mesoscale precipitation features, and how these [...] Read more.

The association between instantaneous extreme precipitation and mesoscale organization over the southeastern United States is not well known. This study addresses whether isolated precipitation features have a distinct distribution and spatial pattern of extreme rain compared to mesoscale precipitation features, and how these distributions and spatial patterns change from spring to summer. Using a four-year surface radar precipitation data set, hourly images of instantaneous extreme rain rates were separated into isolated and mesoscale precipitation features from March through August for the four-year period of 2009–2012. Results show that that compared to isolated convection, mesoscale precipitation organization is more commonly associated with higher extremes in instantaneous rainfall in the southeastern U.S. Extreme rain values tied to mesoscale organization shift eastward and toward the coasts from spring to summer, while extreme rain from isolated convection is mainly a summer phenomenon concentrated in Florida and along the coastal plain. The implication is that dynamical processes favoring mesoscale organization such as high shear associated with baroclinic circulations are more associated with higher values of extreme rain, while thermodynamic forcing and local circulations favoring isolated convection are associated with lower values of extreme rain. Full article

(This article belongs to the Special Issue Weather and Climate Extremes: Current Developments)

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15 pages, 2416 KiB

Open AccessArticle

Variations in Moisture Supply from the Mediterranean Sea during Meteorological Drought Episodes over Central Europe

by Milica Stojanovic, Anita Drumond, Raquel Nieto and Luis Gimeno

Atmosphere 2018, 9(7), 278; https://doi.org/10.3390/atmos9070278 - 19 Jul 2018

Cited by 17 | Viewed by 4569

Abstract

The climate in Central Europe (CEU) during the 20th century is characterized by an overall temperature increase. Severe and prolonged drought events began occurring towards the end and these have continued into the 21st century. This study aims to analyze variations in the [...] Read more.

The climate in Central Europe (CEU) during the 20th century is characterized by an overall temperature increase. Severe and prolonged drought events began occurring towards the end and these have continued into the 21st century. This study aims to analyze variations in the moisture supply from the Mediterranean Sea (MDS) during meteorological drought episodes occurring over the CEU region over the last three decades. A total of 51 meteorological drought episodes (22 with summer onsets, and 29 with winter) are identified over the CEU during the period 1980–2015 through the one-month Standardized Precipitation Evapotranspiration Index (SPEI-1), and their respective indicators, including duration, severity, intensity, and peak values, are then computed. Lagrangian forward-in-time analysis reveals that negative anomalies of moisture coming from the MDS prevail in all episodes except seven. Linear regression analysis between variations in the MDS anomalies and indicators of the drought episodes shows a significant linear relationship between severity, duration, peak values (winter), and MDS anomalies, which implies that drought episodes last longer and are more severe with an increase in the negative anomaly of moisture supply from the MDS. Nevertheless, no linear relationship is found between the intensity and peak values (annual, summer) of drought episodes and anomalies in the moisture contribution from the MDS. Full article

(This article belongs to the Special Issue Weather and Climate Extremes: Current Developments)

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20 pages, 6251 KiB

Open AccessArticle

Combined Effects of Synoptic-Scale Teleconnection Patterns on Summer Precipitation in Southern China

by Chao Wang and Lijuan Wang

Atmosphere 2018, 9(4), 154; https://doi.org/10.3390/atmos9040154 - 19 Apr 2018

Cited by 16 | Viewed by 6419

Abstract

Using ERA-Interim daily reanalysis and precipitation data, the combined effects of East Asia-Pacific (EAP) and Silk Road (SR) teleconnection patterns on summer precipitation in Southern China were investigated on synoptic to sub-monthly timescales. Combined EAP and SR patterns lead to more persistent and [...] Read more.

Using ERA-Interim daily reanalysis and precipitation data, the combined effects of East Asia-Pacific (EAP) and Silk Road (SR) teleconnection patterns on summer precipitation in Southern China were investigated on synoptic to sub-monthly timescales. Combined EAP and SR patterns lead to more persistent and extreme precipitation in the Yangtze River Valley (YRV) and exhibit an obvious zonal advance between the South Asia High (SAH) and Western Pacific Subtropical High (WPSH) prior to its onset. During typical combined events, an overlap between the SAH and WPSH remains in a favorable position for Persistent Extreme Precipitation (PEP). Furthermore, SR-induced acceleration of the westerly jet stream and extra positive vorticity advection provide persistent upper-level divergence for YRV precipitation. An anomalous EAP-related cyclone/anticyclone pair over East Asia induces enhanced low-level southwesterlies to the northern anticyclone flank and northerlies from the mid-latitudes, advecting anomalously abundant moisture toward the YRV, resulting in clear moisture convergence. Moreover, the strong ascent of warmer/moister air along a quasi-stationary front may be crucial for PEP. During decay, the SAH and WPSH diverge from each other and retreat to their normal positions, and the strong ascent of warmer/moister air rapidly weakens to dissipation, terminating PEP in the YRV. Full article

(This article belongs to the Special Issue Weather and Climate Extremes: Current Developments)

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