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Year aridity index patterns in northwest China and the relationship to summer North Atlantic sea surface temperature

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Acta Oceanologica Sinica 2008年第3期27卷 161-171页

作者： YAN Yan ZHAO Xinyi ZHOU Liping College of Urban and Environmental Sciences Laboratory for Earth Surface Processes of Ministry of Education Peking University Beijing 100871 China

Aim to linking the variability of drought in northwest China to the oceanic influence of North Atlantic SSTs at the background of global warming and at the regional climate change shifting stages, year aridity index variations in northwest China and summer North Atlantic sea surface temperature （SST） variations are examined for the 44 a period of 1961-2004 using singular value decomposition （SVD） analysis. Results show that the SST anomalies （SSTA）in the North Atlantic in summer reflected three basic models. The first SVD mode of SST pattern shows a dipole - like variation with the positive center located at southwest and negative center at northeast of extratropical North Atlantic. And it strongly relates to the positive trend in AI variation in northwest China. The second coupled modes display the coherent positive anomalies in extratropical North Atlantic SST and the marked opposite trend of AI variability between north and south of Xinjiang. In addition, the lag correlation analysis of the first mode of SSTA and geopotential heights at 500 hPa variations also shows that the indication of the former influencing the latter configuration, which result in higher air temperature and less precipitation when the SSTA in the North Atlantic Ocean in summer motivated Eurasian circulation of EA pattern, further to influence the wet - dry variations in northwest China by the ocean-to - atmosphere forcing.

关键词： aridity index SSTA teleconnection patterns SVD

Relationship between the Stratospheric Arctic Vortex and Surface Air Temperature in the Midlatitudes of the Northern Hemisphere

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Journal of Meteorological Research 2024年第1期38卷 39-52页

作者： Xue RAN Dingzhu HU Yang ZHANG Mei-Chen LIU Key Laboratory of Meteorological Disaster Ministry of Education(KLME)/Joint International Research Laboratory of Climate and Environmental Change(ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)Nanjing University of Information Science&TechnologyNanjing 210044 School of Atmospheric Sciences Nanjing UniversityNanjing 210023

It is known that different relationships exist between the strength and displacement of the stratospheric polar vortex(SPV),and the surface air temperature(SAT)patterns in Eurasia and North America,but the mechanisms behind these relationships remain unclear,especially on an interannual *** on empirical orthogonal function(EOF)analysis using NCEP reanalysis data over 1958–2018,this study attempts to ascertain the relationship between the SPV intensity and displacement over the Arctic and the SATs in the midlatitudes of the Northern *** results indicate that a strengthened SPV corresponds to an SAT increase in Eurasia and a decrease in eastern North America and *** the SPV is shifted towards Eurasia,however,a corresponding SAT increase occurs in both North America and Eurasia,with a larger increase in North America than in ***,a strengthened SPV tends to correspond to a positive North Atlantic Oscillation-like circulation in the troposphere with negative geopotential height(GH)anomalies in Greenland and eastern North American continent and positive GH anomalies to the north of 45°N in Eurasia,which corresponds to lower SATs in North America than in ***,when the SPV shifted towards Eurasia,it was accompanied by a positive Pacific/North American-like pattern with a deepened Aleutian low,which corresponds to the increasing SATs in North *** tropospheric circulation changes are related to the response of tropospheric planetary wave activity to the SPV.A strengthened SPV corresponds to the weakening of tropospheric planetary wave-1 waves,which is accompanied by a negative GH in North America but a positive GH in *** the SPV shifted towards Eurasia,the tropospheric planetary wave-1(-2)waves strengthened(weakened),and the combined effects of the planetary wave-1 and wave-2 waves would cause positive GH anomalies in both Eurasia and North America.

关键词： stratospheric polar vortex surface air temperature teleconnection patterns planetary waves

A Perspective on the Evolution of Atmospheric Blocking Theories:From Eddy-Mean flow Interaction to Nonlinear Multiscale Interaction

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Advances in Atmospheric Sciences 2023年第4期40卷 553-569页

作者： Dehai LUO Binhe LUO Wenqi ZHANG Key Laboratory of Regional Climate-Environment for Temperate East Asia Institute of Atmospheric PhysicsChinese Academy of ScienceBeijing 100029China University of Chinese Academy of Sciences Beijing 101499China State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal UniversityBeijing 100091China Center for Monsoon System Research Institute of Atmospheric PhysicsChinese Academy of ScienceBeijing 100029China

In this paper,we first review the research advancements in blocking dynamics and highlight the merits and drawbacks of the previous theories of atmospheric ***,the dynamical mechanisms of atmospheric blocking are presented based on a nonlinear multi-scale interaction(NMI)*** studies suggested that the eddy deformation(e.g.,eddy straining,wave breaking,and eddy merging)might lead to the formation and maintenance of atmospheric ***,the results were speculative and problematic because the previous studies,based on the time-mean eddy-mean flow interaction model,cannot identify the causal relationship between the evolution of atmospheric blocking and the eddy *** on the NMI model,we indicate that the onset,growth,maintenance,and decay of atmospheric blocking is mainly produced by the spatiotemporal evolution of pre-existing upstream synoptic-scale eddies,whereas the eddy deformation is a concomitant phenomenon of the blocking *** lifetime of blocking is mainly determined by the meridional background potential vorticity gradient(PVy)because a small PVyfavors weak energy dispersion and strong nonlinearity to sustain the *** the zonal movement of atmospheric blocking is associated with the background westerly wind,PVy,and the blocking *** this NMI model,a bridge from the climate change to sub-seasonal atmospheric blocking and weather extremes might be established via examining the effect of climate change on ***,it is expected that using the NMI model to explore the dynamics of atmospheric blocking and its change is a new direction in the future.

关键词： atmospheric blocking teleconnection patterns eddy deformation potential vorticity gradient climate change nonlinear multiscale interaction

THE EFFECTS OF GENERAL CIRCULATION ANOMALIES ON PRECIPITATION IN THE RAINING SEASON OF SHANDONG

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Journal of Tropical Meteorology 2005年第1期11卷 68-77页

作者：王庆孙即霖刘诗军周晓英 The Meteorological Institute of Shandong Province Jinan 250031 China China Ocean University Qingdao 266003 China China Ocean University Qingdao 266003 China The Meteorological Institute of Shandong Province Jinan 250031 China Shanghai Marine Forecast Center Shanghai 200081 China

Using the monthly mean reanalysis data of height, wind and vertical velocity of NCEP/NCAR from 1958 to 2003, the characteristics of 500hPa height anomalies in the Northern Hemisphere, convergence and divergence on the levels of 200hPa and 925hPa and vertical stream over the Shandong province were studied and compared with that over North China. The study shows that the teleconnection pattern called East Asia-Pacific pattern (EAP) plays important roles in the summer rainfall of Shandong. Weaker Okhotsk sea high, stronger upward stream over tropical areas and Shandong and northward location of subtropical high and stronger Indian low, are likely to lead to more rain in Shandong province in summer, but there are some flood (drought) years in which these characteristics such as the location and intensity of subtropical high change with the least extent. The difference between Shandong and North China in 500hPa height is that there is a teleconnection pattern called Europe / Asia pattern in North China, while there is a negative East Asia Pattern in Shandong during drought years. There is a teleconnection relation between Shandong summer rainfall and convective activities happening in tropical areas in spring and summer accomplished by the Rossby waves. During the flood years in Shandong, the convective activities happening in tropical India Ocean and tropical west Pacific and Walker circulation are much stronger than that during the drought years, but the convective activities happening in tropical east Pacific are weaker than those during the drought years.

关键词： General circulation precipitation in summer teleconnection patterns affecting mechanisms