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18 pages, 7629 KiB

Open AccessArticle

Bioclimatic Conditions of June 2019 in Poland on a Multi-Year Background (1966–2019)

by Arkadiusz Marek Tomczyk

Atmosphere 2021, 12(9), 1117; https://doi.org/10.3390/atmos12091117 - 31 Aug 2021

Cited by 6 | Viewed by 1454

The study objective was to characterise human-biometeorological conditions in the summer season in the period 1966–2019 in Poland, with particular consideration of June 2019. The study was conducted based on data from the Institute of Meteorology and Water Management—National Research Institute (IMGW–PIB) for [...] Read more.

The study objective was to characterise human-biometeorological conditions in the summer season in the period 1966–2019 in Poland, with particular consideration of June 2019. The study was conducted based on data from the Institute of Meteorology and Water Management—National Research Institute (IMGW–PIB) for the years 1966–2019. The data provided the basis for the calculation of the Universal Thermal Climate Index (UTCI). The study revealed high spatial variability of human-biometeorological conditions in Poland, with strenuous character intensifying from the north to the south of the country. An increase in UTCI in the summer season was recorded in the studied multi-annual period. It was the most intensive in the north-eastern Poland. The consequence of the observed changes was an increase in the frequency of days with heat stress categories (days with UTCI > 26.0 °C), and a decrease in the frequency of days with cold stress categories (days with UTCI < 9.0 °C). Season 2019 stood out at the scale of the entire country in the context of the multi-annual period. This particularly concerns June, when mean monthly UTCI values were the highest in the analysed multi-annual period. Full article

(This article belongs to the Special Issue Temperature Extremes and Atmospheric Circulation)

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21 pages, 3127 KiB

Open AccessArticle

Seasonal Variability of Trends in Regional Hot and Warm Temperature Extremes in Europe

by Agnieszka Sulikowska and Agnieszka Wypych

Atmosphere 2021, 12(5), 612; https://doi.org/10.3390/atmos12050612 - 08 May 2021

Cited by 11 | Viewed by 3488

Abstract

Extremely hot or warm weather over the course of the year may have significant impacts on many aspects of human life, the economy, and the natural environment. Until now a thorough assessment of changes of extreme heat or warm events in Europe was [...] Read more.

Extremely hot or warm weather over the course of the year may have significant impacts on many aspects of human life, the economy, and the natural environment. Until now a thorough assessment of changes of extreme heat or warm events in Europe was hindered by the number of metrics employed, time periods examined, and most studies being conducted in the summer season only. Here, we employ the Extremity Index (EI) to investigate long-term trends in extremely hot or warm days in Europe over the course of the year, with a special focus on their frequency, spatial extent, and intensity. An extreme temperature event (ETE) is defined as a day with an unusually high temperature for a given location and season, even if such a temperature would not be considered extremely high in an absolute sense. The research is conducted in five spatial domains that together cover a large portion of Europe. The period of the most recent 70 years is considered. In all examined regions, mainly significant increasing trends since 1950 are evident for seasonal EI; therefore, also for ETE frequency, intensity, and spatial range. Yet, every region is characterized by its own event pattern, and trends across the continent strongly vary geographically and seasonally. Our study highlights that examined trends of temperature extremes are accelerating and in the last 40 years the rate of change has been even more than three times greater than in the entire study period. The greatest changes were noted for the summer season in Central Europe and Eastern Europe for the most recent 40-year period. Full article

(This article belongs to the Special Issue Temperature Extremes and Atmospheric Circulation)

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12 pages, 6596 KiB

Open AccessArticle

Wintertime Cold Extremes in Northeast China and Their Linkage with Sea Ice in Barents-Kara Seas

by Yongyue Luo, Chun Li, Jian Shi, Xiadong An and Yaqing Sun

Atmosphere 2021, 12(3), 386; https://doi.org/10.3390/atmos12030386 - 16 Mar 2021

Cited by 5 | Viewed by 2360

Abstract

The impacts of Arctic sea ice on the interannual variability of winter extreme low temperature (WELT) in Northeast China (NEC) and the associated atmospheric circulation patterns are explored in this study based on meteorological observation and the National Centers for Environmental Prediction-National Center [...] Read more.

The impacts of Arctic sea ice on the interannual variability of winter extreme low temperature (WELT) in Northeast China (NEC) and the associated atmospheric circulation patterns are explored in this study based on meteorological observation and the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP/NCAR) reanalysis data. Results show that WELT in NEC has prominent interannual variability. We further use ±0.8 standard deviation as the threshold to select the years of frequent and rare extreme low temperature anomalies. Using composite analysis, we find that there are significant negative geopotential height anomalies at 500 hPa over NEC and positive geopotential height anomalies along the Arctic region, which represent the intensification of the East Asian trough (EAT) and the negative Arctic Oscillation (AO) phase in the years of more frequent WELT. The opposite characteristics are detected in the years of rare WELT. Furthermore, we determine that the Barents-Kara Seas are key sea ice regions in Arctic area. In the years of frequent WELT, the decrease of autumn Barents-Kara Seas sea ice and the positive sea surface temperature anomaly can last until the following winter, which is conducive to the intensification of anticyclonic anomalies in Ural regions and the northward extension of Ural ridge (UR). The northerly flow in front of UR guides the cold air penetrating southward from polar regions. Moreover, the anomalous cyclone over East Asia deepens the EAT. The northerly wind behind EAT guides the cold air to the NEC region, causing the wintertime low temperature there. The almost opposite situation occurs in the years of rare WELT. Full article

(This article belongs to the Special Issue Temperature Extremes and Atmospheric Circulation)

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19 pages, 17036 KiB

Open AccessArticle

Hot Days and Heat Waves in Poland in the Period 1951–2019 and the Circulation Factors Favoring the Most Extreme of Them

by Joanna Wibig

Atmosphere 2021, 12(3), 340; https://doi.org/10.3390/atmos12030340 - 06 Mar 2021

Cited by 15 | Viewed by 1970

Abstract

The aim of the study is to analyze the occurrence of hot days and heat waves in Poland, their intra-annual distribution, and their long-term variability, and to present the circulation factors favoring the appearance of extensive waves in the country. Hot days were [...] Read more.

The aim of the study is to analyze the occurrence of hot days and heat waves in Poland, their intra-annual distribution, and their long-term variability, and to present the circulation factors favoring the appearance of extensive waves in the country. Hot days were days with Tmax not lower than the threshold value defined by the 95th percentile of summer Tmax in the period 1961–1990. Atmospheric circulation was described using sea level pressure, geopotential of 700 and 500 hPa level, and horizontal and vertical wind on these levels. A statistically significant increase in the number of hot days in the entire study period and a significant acceleration in growth after 1980 were shown. In the entire analyzed period, only 11 waves were found covering at least 25% of the country area and lasting no less than a week. Among them, only one occurred before 1990, and more than half were observed in the last decade. Four circulation patterns favoring the extensive heat waves were distinguished differing the location of main baric center location. Spatial and temporal distribution of vertical velocity anomalies allows distinguishing clear phases of strengthening, stabilization, and weakening of anticyclone accompanying the occurrence of a heat wave. Full article

(This article belongs to the Special Issue Temperature Extremes and Atmospheric Circulation)

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22 pages, 7182 KiB

Open AccessArticle

Multi-Annual Changes in Heat Stress Occurrence and Its Circulation Conditions in the Polish–Saxon Border Region

by Bartłomiej Miszuk

Atmosphere 2021, 12(2), 163; https://doi.org/10.3390/atmos12020163 - 27 Jan 2021

Cited by 9 | Viewed by 1662

Abstract

Heat stress is one of the most critical factors affecting human life. In Central Europe, its influence is noticeable, especially in the Polish–Saxon region, which is a very popular tourist region also inhabited by a high number of elders. The main goal of [...] Read more.

Heat stress is one of the most critical factors affecting human life. In Central Europe, its influence is noticeable, especially in the Polish–Saxon region, which is a very popular tourist region also inhabited by a high number of elders. The main goal of this paper was to assess multi-annual changes in heat stress occurring in the region, considering the frequency of heat days, the UTCI (Universal Thermal Climate Index), and circulation conditions. The research showed that all the thermal and biothermal indices in this region significantly increased during 1971–2019 in the lowlands, the mountain foreland, and the lower mountain zone. In terms of the UTCI, a negative trend for cold stress frequency was noticed in the entire region in favor of an increase in a tendency toward thermoneutral conditions and heat stress. This concerns especially strong and very strong heat stress (UTCI > 32 °C), in which positive trends were observed for most of the stations located in the lower hypsometric zones. The results also showed that heat stress mainly occurs on days with anticyclonic circulation. Analysis of selected cases of heat waves in the 21st century indicated that the lower hypsometric zones are characterized by a very high UTCI, while the summit zone is free from heat stress occurrence. Full article

(This article belongs to the Special Issue Temperature Extremes and Atmospheric Circulation)

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17 pages, 3483 KiB

Open AccessArticle

Precursory Signals (SST and Soil Moisture) of Summer Surface Temperature Anomalies over the Tibetan Plateau

by Huimei Wang, Ge Liu, Sai Wang and Kejun He

Atmosphere 2021, 12(2), 146; https://doi.org/10.3390/atmos12020146 - 24 Jan 2021

Cited by 8 | Viewed by 1668

Abstract

Understanding the variability of surface air temperature (SAT) over the Tibetan Plateau (TP) and its precursory signals is of great benefit to climate change adaptation and socioeconomic development. This study explores the precursory signals of summer SATs over the TP in oceanic and [...] Read more.

Understanding the variability of surface air temperature (SAT) over the Tibetan Plateau (TP) and its precursory signals is of great benefit to climate change adaptation and socioeconomic development. This study explores the precursory signals of summer SATs over the TP in oceanic and land boundary conditions. The results show that the summer eastern TP SAT is significantly correlated with three precursors in April: the high-latitude North Atlantic sea surface temperature (SST), the northern Indian Ocean SST, and the Indian soil moisture (SM). The April SST anomalies (SSTAs) in the high-latitude North Atlantic can exert a cross-season impact on the summer SAT over the TP through two processes. The SSTAs in the high-latitude North Atlantic maintain from April to summer and modulate atmospheric circulation over the eastern TP through exciting a downstream wave train during summer, and finally modulate the summer SAT over the eastern TP. In addition to the above process, the April SSTAs in the high-latitude North Atlantic may remotely regulate simultaneous SM in the Indian subcontinent through stimulating a downstream wave train pattern. Through a persistent SM–precipitation interaction, the April Indian SM anomaly can affect the local precipitation and associated condensation heating anomalies during the ensuing summer, which forces an anomalous cyclone–anticyclone pattern around the TP and accordingly affects the summer SAT over the eastern TP. Additionally, the SSTAs in the northern Indian Ocean can persist from April to summer and adjust the intensity and location of the western North Pacific subtropical high through the Kelvin-wave-induced Ekman divergence during summer, eventually affecting the summer eastern TP SAT. The three precursory signals, which synergistically contribute to the variability of the summer eastern TP SAT, can be applied in predicting the summer SAT over the eastern TP. Full article

(This article belongs to the Special Issue Temperature Extremes and Atmospheric Circulation)

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20 pages, 6708 KiB

Open AccessArticle

Large Day-to-Day Variability of Extreme Air Temperatures in Poland and Its Dependency on Atmospheric Circulation

by Katarzyna Szyga-Pluta

Atmosphere 2021, 12(1), 80; https://doi.org/10.3390/atmos12010080 - 07 Jan 2021

Cited by 7 | Viewed by 1690

Abstract

The primary purpose of the study was the determination of the spatial day-to-day variability of extreme air temperatures in Poland and the dependency of large temperature changes on atmospheric circulation in accordance with the Grosswetterlagen (GWL) classification. The goal was achieved based on [...] Read more.

The primary purpose of the study was the determination of the spatial day-to-day variability of extreme air temperatures in Poland and the dependency of large temperature changes on atmospheric circulation in accordance with the Grosswetterlagen (GWL) classification. The goal was achieved based on data from 1966 to 2015, made available by the Institute of Meteorology and Water Management—National Research Institute. Day-to-day changes in maximum and minimum air temperatures were designated with a rate of ≥6 °C (large) and with a rate of ≥12 °C (very large) and their spatial distribution was presented. Finally, the analysis of the dependency of considerable temperature changes on atmospheric circulation in accordance with the Grosswetterlagen (GWL) classification was conducted. The obtained results showed that in Poland in the period 1966–2015 there was a statistically significant increase in the number of large changes in both Tmax and Tmin. The number of large changes in Tmax increases from north to south, and the number of large changes in Tmin from north to east and south of Poland indicate the range of the effect of marine and continental properties on the climate of Poland and the influence of local relief as well as the atmospheric circulation impact. Large changes in Tmax occur more frequently in spring and in Tmin in winter. Large changes in Tmax and Tmin are mainly recorded during cyclonic circulation, however, the anticyclonic circulation types favour especially large decreases in Tmin. Full article

(This article belongs to the Special Issue Temperature Extremes and Atmospheric Circulation)

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19 pages, 7552 KiB

Open AccessArticle

Changes in Air Temperature and Snow Cover in Winter in Poland

by Arkadiusz M. Tomczyk, Ewa Bednorz and Katarzyna Szyga-Pluta

Atmosphere 2021, 12(1), 68; https://doi.org/10.3390/atmos12010068 - 05 Jan 2021

Cited by 28 | Viewed by 3272

Abstract

The primary objective of the paper was to characterize the climatic conditions in the winter season in Poland in the years 1966/67–2019/20. The study was based on daily values of minimum (Tmin) and maximum air temperature (Tmax), and daily values of snow cover [...] Read more.

The primary objective of the paper was to characterize the climatic conditions in the winter season in Poland in the years 1966/67–2019/20. The study was based on daily values of minimum (Tmin) and maximum air temperature (Tmax), and daily values of snow cover depth. The study showed an increase in both Tmin and Tmax in winter. The most intensive changes were recorded in north-eastern and northern regions. The coldest winters were recorded in the first half of the analyzed multiannual period, exceptionally cold being winters 1969/70 and 1984/85. The warmest winters occurred in the second half of the analyzed period and among seasons with the highest mean Tmax, particularly winters 2019/20 and 1989/90 stood out. In the study period, a decrease in snow cover depth statistically significant in the majority of stations in Poland was determined, as well as its variability both within the winter season and multiannual. Full article

(This article belongs to the Special Issue Temperature Extremes and Atmospheric Circulation)

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13 pages, 8980 KiB

Open AccessEditor’s ChoiceArticle

A Hot Blob Eastward of New Zealand in December 2019

by Jian Shi, Ziyan Chen, Saisai Ding and Yiqun Lu

Atmosphere 2020, 11(12), 1267; https://doi.org/10.3390/atmos11121267 - 24 Nov 2020

Cited by 2 | Viewed by 2265

Abstract

A hot blob for near-surface water was identified eastward of New Zealand in the South Pacific in December 2019, which was the second strongest event on record in this region. Its sea surface temperature anomalies reached up to 5 °C, and the anomalous [...] Read more.

A hot blob for near-surface water was identified eastward of New Zealand in the South Pacific in December 2019, which was the second strongest event on record in this region. Its sea surface temperature anomalies reached up to 5 °C, and the anomalous warming penetrated around 40 m deep vertically. From the atmospheric perspective, the anomalous high-pressure system from the surface up to 300 hPa lasted for about 50 days, accompanied by the blocking pattern at 500 hPa and a deep warming air column extending downward to the surface. A mixed-layer heat budget analysis revealed that the surface heat flux term was the primary factor contributing to the development of this hot blob, with more shortwave radiation due to the persistent high-pressure system and lack of clouds as well as higher temperature of the troposphere aloft denoted by sensible heat. The oceanic contribution including the horizontal advection and vertical entrainment was changeable and accounted for less than 50%. Moreover, we used the strongest hot blob event which peaked in December 2001 as another example to evaluate the robustness of results derived from the 2019 case. The results show similar circulation features and driving factors, which indicate the robustness of the above characteristics. Full article

(This article belongs to the Special Issue Temperature Extremes and Atmospheric Circulation)

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19 pages, 2706 KiB

Open AccessArticle

Changes of Extreme Temperature and Its Influencing Factors in Shiyang River Basin, Northwest China

by Junju Zhou, Jumei Huang, Xi Zhao, Li Lei, Wei Shi, Lanying Wang, Wei Wei, Chunfang Liu, Guofeng Zhu and Xuemei Yang

Atmosphere 2020, 11(11), 1171; https://doi.org/10.3390/atmos11111171 - 29 Oct 2020

Cited by 17 | Viewed by 1882

Abstract

The increase in the frequency and intensity of extreme weather events around the world has led to the frequent occurrence of global disasters, which have had serious impacts on the society, economic and ecological environment, especially fragile arid areas. Based on the daily [...] Read more.

The increase in the frequency and intensity of extreme weather events around the world has led to the frequent occurrence of global disasters, which have had serious impacts on the society, economic and ecological environment, especially fragile arid areas. Based on the daily maximum temperature and daily minimum temperature data of four meteorological stations in Shiyang River Basin (SRB) from 1960 to 2015, the spatio-temporal variation characteristics of extreme temperature indices were analyzed by means of univariate linear regression analysis, Mann–Kendall test and correlation analysis. The results showed that the extreme temperatures warming indices and the minimum of daily maximum temperature (TXn) and the minimum of daily minimum temperature (TNn) of cold indices showed an increasing trend from 1960 to 2016, especially since the 1990s, where the growth rate was fast and the response to global warming was sensitive. Except TXn and TNn, other cold indices showed a decreasing trend, especially Diurnal temperature (DTR) range, which decreased rapidly, indicating that the increasing speed of daily min-temperature were greater than of daily max-temperature in SRB. In space, the change tendency rate of the warm index basically showed an obvious altitude gradient effect that decreased with the altitude, which was consistent with Frost day (FD0) and Cool nights (TN10p) in the cold index, while Ice days (ID0) and Cool days (TX10p) are opposite. The mutation of the cold indices occurred earlier than the warm indices, illustrating that the cold indices in SRB were more sensitive to global warming. The change in extreme temperatures that would have a significant impact on the vegetation and glacier permafrost in the basin was the result of the combined function of different atmospheric circulation systems, which included the Arctic polar vortex, Western Pacific subtropical high and Qinghai-tibet Plateau circulation. Full article

(This article belongs to the Special Issue Temperature Extremes and Atmospheric Circulation)

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20 pages, 5546 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Interdecadal Variations in Extreme High–Temperature Events over Southern China in the Early 2000s and the Influence of the Pacific Decadal Oscillation

by Baoyan Zhu, Bo Sun, Hua Li and Huijun Wang

Atmosphere 2020, 11(8), 829; https://doi.org/10.3390/atmos11080829 - 06 Aug 2020

Cited by 20 | Viewed by 3549

Abstract

This study documents a sudden interdecadal variation in the frequency of extreme high–temperature events (FEHE) over southern China during summer in the early 2000s, which is characterized by a relatively small (large) FEHE during 1991–2000 (2003–2018). The composite analysis on the extreme high–temperature [...] Read more.

This study documents a sudden interdecadal variation in the frequency of extreme high–temperature events (FEHE) over southern China during summer in the early 2000s, which is characterized by a relatively small (large) FEHE during 1991–2000 (2003–2018). The composite analysis on the extreme high–temperature events (EHEs) over southern China indicates that the occurrence of EHEs is mainly influenced by increased downward surface net shortwave radiation, which is induced by the cloud–forced radiation anomalies associated with reduced cloud; the reduced cloud is attributed to anomalous descent motion and decreased water vapor content in the troposphere. Compared to the situation during 1991–2000, anomalous descent motion and decreased atmospheric water vapor content occurred over southern China in summer during 2003–2018, providing a more favorable climatic condition for EHEs. This interdecadal variation is associated with the strengthened Pacific Walker circulation after 2003. The Pacific decadal oscillation (PDO) is suggested to be an important driver for the above interdecadal variation, which shifted from a positive phase towards a negative phase after 2003. Numerical experiments demonstrate that a negative phase of PDO may induce a strengthened Walker circulation and anomalous atmospheric descent motion as well as water vapor divergence over Southern China. Full article

(This article belongs to the Special Issue Temperature Extremes and Atmospheric Circulation)

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14 pages, 5096 KiB

Open AccessArticle

Evaluation of Four Reanalysis Datasets against Radiosonde over Southwest Asia

by Ali S. Alghamdi

Atmosphere 2020, 11(4), 402; https://doi.org/10.3390/atmos11040402 - 17 Apr 2020

Cited by 16 | Viewed by 2661

Abstract

Upper-air observational networks in Southwest Asia (SWA) are geographically sparse and reanalysis datasets (RDs) are a typical alternative. However, RDs can perform with varying degrees of quality and accuracy due to differences in assimilation schemes and input observations, among other factors. Geopotential height [...] Read more.

Upper-air observational networks in Southwest Asia (SWA) are geographically sparse and reanalysis datasets (RDs) are a typical alternative. However, RDs can perform with varying degrees of quality and accuracy due to differences in assimilation schemes and input observations, among other factors. Geopotential height (gph), air temperature (tmp) and horizontal wind (U and V) modelled by the Japanese 55-year Reanalysis (JRA-55), the European Centre for Medium-Range Weather Forecasts Reanalysis Interim (ERA-I), the ERA fifth-generation (ERA-5), and the National Aeronautics and Space Administration (NASA) Modern Era Retrospective Analysis for Research and Applications version 2 (MERRA), are compared with radiosonde observations at three standard vertical levels (850, 500 and 300 hPa). Results showed that most RDs represent the general climatology, and ERA-5 tended to show the smallest agreements in most cases. RDs did not show consistent performance across seasons, variables, and pressure levels. RDs tended to conduct reasonable estimates over subregions with less complex topography. RDs showed better resampling performance at the upper and lower ends of sounding data distributions more frequently than around the means for most of the variables. This highlights the high potential usefulness of RDs in studying extremes over the region. Full article

(This article belongs to the Special Issue Temperature Extremes and Atmospheric Circulation)

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