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Monthly Variations of atmospheric circulations Associated with Haze Pollution in the Yangtze River Delta and North China

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Advances in atmospheric Sciences 2021年第4期38卷 569-580页

作者： Xinyu ZHANG Zhicong YIN Huijun WANG Mingkeng DUAN Key Laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological DisastersNanjing University of Information Science and TechnologyNanjing 210044China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519080China Nansen-Zhu International Research Centre Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China

Haze pollution in early winter(December and January) in the Yangtze River Delta(YRD) and in North China(NC)are both severe;however, their monthly variations are significantly different. In this study, the dominant large-scale atmospheric circulations and local meteorological conditions were investigated and compared over the YRD and NC in each month. Results showed that the YRD(NC) is dominated by the so-called Scandinavia(East Atlantic/West Russia)pattern in December, and these circulations weaken in January. The East Asian December and January monsoons over the YRD and NC have negative correlations with the number of haze days. The local descending motion facilitates less removal of haze pollution over the YRD, while the local ascending motion facilitates less removal of haze pollution over NC in January, despite a weaker relationship in December. Additionally, the monthly variations of atmospheric circulations showed that adverse meteorological conditions restrict the vertical(horizontal) dispersion of haze pollution in December(January) over the YRD, while the associated local weather conditions are similar in these two months over NC.

关键词： monthly haze pollution atmospheric circulations Yangtze River Delta North China

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Synergistic effects of multiple driving factors on the runoff variations in the Yellow River Basin,China

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Journal of Arid Land 2021年第8期13卷 835-857页

作者： WANG Junjie SHI Bing ZHAO Enjin CHEN Xuguang YANG Shaopeng College of Engineering Ocean University of ChinaQingdao 266100China Hubei Key Laboratory of Marine Geological Resources China University of GeosciencesWuhan 430074China College of Ocean Science and Engineering Shandong University of Science and TechnologyQingdao 266590China

River runoff plays an important role in watershed ecosystems and human survival,and it is controlled by multiple environmental ***,the synergistic effects of various large-scale circulation factors and meteorological factors on the runoff on different time-frequency scales have rarely been *** light of this,the underlying mechanism of the synergistic effects of the different environmental factors on the runoff variations was investigated in the Yellow River Basin of China during the period 1950-2019 using the bivariate wavelet coherence(WTC)and multiple wavelet coherence(MWC)***,the continuous wavelet transform(CWT)method was used to analyze the multiscale characteristics of the *** results of the CWT indicate that the runoff exhibited significant continuous or discontinuous annual and semiannual oscillations during the study *** inter-annual time scales were also observed for the runoff in the Yellow River *** meteorological factors better explained the runoff variations on seasonal and annual time *** average wavelet coherence(AWC)and the percent area of the significant coherence(PASC)between the runoff and individual meteorological factors were 0.454 and 19.89%,*** circulation factors mainly regulated the runoff on the inter-annual and decadal time scales with more complicated phase relationships due to their indirect effects on the *** AWC and PASC between the runoff and individual circulation factors were 0.359 and 7.31%,*** MWC analysis revealed that the synergistic effects of multiple factors should be taken into consideration to explain the multiscale characteristic variations of the *** AWC or MWC ranges were 0.320-0.560,0.617-0.755,and 0.819-0.884 for the combinations of one,two,and three circulation and meteorological factors,*** PASC ranges were 3.53%-33.77%,12.93%-36.90%,and 20.67%-39.34%for the combinations one,two,and three driving facto

关键词： synergistic effects precipitation runoff variations atmospheric circulations multiple wavelet coherence Yellow River Basin

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Extreme characteristics and causes of the drought event in the whole Yangtze River Basin in the midsummer of 2022

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Advances in Climate Change Research 2023年第5期14卷 642-650页

作者： Zhuo-Zhuo LYU Hui GAO Rong GAO Ting DING Climate Studies Key Laboratory National Climate CenterChina Meteorological AdministrationBeijing 100081China Key Laboratory of Meteorological Disaster(KLME) Ministry of Education&Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)Nanjing University of Information Science&TechnologyNanjing 210044China

Due to their huge socio-economic impacts and complex formation causes,extreme and continuous drought events have become the focus and nodus of research in recent *** the midsummer(July-August)of 2022,a severe drought event occurred in the whole Yangtze River Basin(YRB),*** that period,the precipitation in the upper,middle and lower reaches of the YRB dropped over 40%less than the 1961-2021 climatic mean,which had never happened ***,the temperature was the highest during *** record-breaking magnitude of less rainfall and high temperature directly led to the continuous development of this extreme drought *** atmospheric moisture budget analysis revealed that the YRB midsummer rainfall anomaly was dominated by the anomalous powerful vertical moisture advection,which was derived from the strongest descending motion over the whole YRB in the 2022 midsummer during *** western Pacific subtropical high(WPSH)during the midsummer remained stronger,more westward and lasted longer than the climatic *** a result,the whole YRB was controlled by a positive geopotential height *** evidence revealed that the anomalous subtropical zonal flow played a crucial role in inducing the extreme descent over the ***,the anomalous upper-tropospheric easterly flow over the YRB in 2022 is the strongest during 1981-2022,modulating the generation of the unprecedented descent anomaly over the *** likelihood that an integrated connection of severe drought in East Asia and flood in West Asia and northwestern South Asia would increase when the extremely strong easterly anomalies in the upper troposphere emerged and induced descending adiabatic flow on the eastern sides of the Tibetan *** results of this study can provide scientific insights into the predictability of extreme drought events and provide ways to improve predictions.

关键词： Yangtze River Basin Midsummer extreme drought atmospheric circulations Zonal flow Water vapour budget Subtropical high

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Opposite atmospheric Decadal Trends in Northern-Hemisphere Winter Time

Opposite Atmospheric Decadal Trends in Northern-Hemisphere W...

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中国气象学会2004年年会

作者： Hu Yongyun (Department of atmospheric Sciences, Beijing University, Beijing 100871)

＜正＞In the past few decades, the climate system has demonstrated noticeable trends. Using NCEP/NCAR reanalysis data, we show that in the Northern-Hemisphere extratropics and high latitudes decadal atmospheric trends exhibit opposite tendencies between early winter （November-December） and late winter （February-March） since the late 1970s. In early-winter months, the trends are characterized by surface air temperature （SAT） cooling over high-latitude continents associated with warming over the Arctic polar region, decelerated extratropical zonal winds in both the troposphere and stratosphere accompanied by increased poleward wave fluxes, warming in the stratospheric Arctic contrasted with cooling in the midlatitude stratosphere, and a weakened Ferrel cell. In contrast, the late-winter trends are characterized by SAT warming over high-latitude continents associated with cooling over the Arctic biased toward Greenland, accelerated extratropical zonal winds accompanied by enhanced equatorward wave fluxes, strong cooling in the stratospheric Arctic contrasted with relatively weak cooling in the midlatitude stratosphere, and a strengthened Ferrel cell. In both early and late winter months, these trends show spatial coherence of interaction between the troposphere and the stratosphere as well as between the tropics and higher latitudes. Whether and how the opposite trends are caused by external forcing, such as increasing greenhouse gases and stratospheric ozone depletion, will be discussed.

关键词： climate trends atmospheric circulations planetary waves increrasing greenhouse gases ozone depletion

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The Response of Geopotential Height Anomalies to El Niño and La Niña Conditions and Their Implications to Seasonal Rainfall Variability over the Horn of Africa

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atmospheric and Climate Sciences 2022年第2期12卷 475-492页

作者： Solomon Gunta Hejamady Gangadhara Bhat Busnur Rachotappa Manjunatha Department of Physics College of Natural and Computational Sciences Wolaita Sodo University Wolaita Sodo Ethiopia Remote Sensing and Geo-Informatics Division Department of Marine Geology Faculty of Science and Technology Mangalore University Karnataka India

In this study, we unveil atmospheric circulation anomalies associated with the large-scale tropical teleconnections using National Center for Environmental Prediction (NCEP) reanalysis dataset. Composite analyses have been performed to know the impact of large-scale tropical circulations on the Horn of Africa. The composite analysis performed at the geopotential height of 850 Mb and 200 Mb, and precipitation rate (mm/day) during six strong El Niño and La Niña episodes revealed that the large-scale tropical variability induced climate anomalies in space and time. A substantial decrease in upper-level height (200 Mb) has been observed in the study area during El Niño composite years as compared to the La Niña years. During El Niño conditions, the upper-level divergence initiates low-level vertical motion, thereby enhancing convection, however, during La Niña composite years, nearly contrasting situations are noticed in Belg (February to May) season in Ethiopia. However, geopotential height anomalies at 850 Mb are above-normal during the strong El Niño years, suggesting suppressed convection due to vertical shrinking and enhancement of divergence at the lower level. Compared to the Belg (February to May), geopotential anomalies were generally positive during the Kiremt (June to September) season, thereby suppressing the rainfall, particularly in Southern Ethiopia and Northern Part of Kenya. In contrast, an increase in rainfall was observed during the Belg season (February to May).

关键词： Geopotential Height Composite Analysis ENSO atmospheric circulations NCEP Reanalysis Tropical SST Anomalies Teleconnections Belg Kiremt

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INVESTIGATION OF POSSIBLE EFFECT OF GRAVITATIONAL FIELD INHOMOGENEITIES ON TROPICAL CYCLONES

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Tropical Cyclone Research and Review 2013年第2期2卷 124-130页

作者： MIKHAIL YAROSHEVICH Research and Production Association “Typhoon”

Analysis of field data was performed with respect to variations in the intensity and traveling of tropical cyclones resulting from a possible effect of the gravity *** obtained results suggest that this kind of influence may exist,even though it seems to be weaker than some of other known *** to the observed data,a decreased gravity is conducive to tropical cyclone intensification.

关键词： gravity anomalies atmospheric circulations tropical cyclones

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