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Trends of Temperature Extremes in China and their Relationship with Global Temperature Anomalies

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Advances in Atmospheric Sciences 2010年第4期27卷 937-946页

作者：黄丹青钱永甫朱坚 institute of severe weather & climate School of Atmospheric SciencesNanjing University

Changes of temperature extremes over China were evaluated using daily maximum and minimum temperature data from 591 stations for the period 1961-2002. A set of indices of warm extremes, cold extremes and daily temperature range （DTR） extremes was studied with a focus on trends. The results showed that the frequency of warm extremes （F WE） increased obviously in most parts of China, and the intensity of warm extremes （I WE） increased significantly in northern China. The opposite distribution was found in the frequency and intensity of cold extremes. The frequency of high DTR extremes was relatively uniform with that of intensity： an obvious increasing trend was located over western China and the east coast, while significant decreases occurred in central, southeastern and northeastern China; the opposite distribution was found for low DTR extreme days. Seasonal trends illustrated that both F WE and I WE showed signifi- cant increasing trends, especially over northeastern China and along the Yangtze Valley basin in spring and winter. A correlation technique was used to link extreme temperature anomalies over China with global temperature anomalies. Three key regions were identified, as follows： northeastern China and its coastal areas, the high-latitude regions above 40~0N, and southwestern China and the equatorial eastern Pacific.

关键词： temperature extremes daily threshold trend global temperature anomalies

Decadal-to-interdecadal response and adjustment of the North Pacific to prescribed surface forcing in an oceanic general circulation model

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Acta Oceanologica Sinica 2006年第3期25卷 11-24页

作者： FANG Jiabei RONG Xinyao YANG Xiuqun institute of severe weather ＆ climate Nanjing University Nanjing 210093 China

The simulation of a higher-resolution oceanic GCM forced with COADS surface conditions during 1945 ～ 1993 was analyzed with insight into how the North Pacific responds to the surface forcing. The decadal-to-interdecadal variabilities in the thermal and dynamical fields especially those associated with the 1976/1977 regime shift in the North Pacific were investigated. The model successfully captures the dominant SST anomaly mode on the decadal-to-interdecadal time scales as well as the major feature of SST anomalies in the 1976/1977 regime shift. The model also successfully reproduces two typical subduction events that link the tropical and extratropical oceanic temperature anomalies during the 1970s and the 1980s. Most importantly, the model simulates the dynamical adjustment of the upper ocean under the surface wind forcing. The typical surface circulation anomaly is characterized by a pattern that is simultaneously related to the wind stress anomalies. The typical anomalous pattern for the entire upper-ocean is characterized by coherent anomalies of two oceanic gyres, i.e. , the subtropical and subpolar gyres. The delayed response and slower adjustment of the gyres, especially of the subpolar gyre, give rise to a persistent SST anomaly in the central North Pacific. The upper-ocean heat budgets in three target regions, i.e. , the central North Pacific, the Californian coastal region and the KOE region, are examined. The cooling in the central North Pacific around 1976/1977 is attributed to the heat flux and mefidional advection anomalies. The associated warming in the Californian coastal region is only due to the heat flux anomaly. A cooling shift in the KOE region which lags that in the central basin by 3 to 4 a is largely due to the meridional advection anomaly and the heat flux acts only as a damping role.

关键词： North Pacific Ocean decadal-to-interdecadal variability subtropical gyre subpolar gyre

Western Pacific Jet Stream Anomalies at 200 hPa in Winter Associated with Oceanic Surface Heating and Transient Eddy Activity

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Acta meteorologica Sinica 2007年第3期21卷 277-289页

作者：任雪娟张耀存 institute of severe weather and climate Department of Atmospheric SciencesNanjing UniversityNanjing 210093

The relationships between the 200-hPa westerly jet stream anomalies over the East Asian coastal waterwestern Pacific （WPJS）, and the oceanic surface heating and synoptic-scale transient eddy （STE） activity anomalies over the North Pacific in wintertime are examined by using ERA-40 and NCEP/NCAR reanalysis data. The analysis demonstrates that the surface heating and the STE anomalies have different patterns, corresponding to the three WPJS anomalous modes, respectively. In the first WPJS anomalous mode, the WPJS main part shows no robust anomaly. The anomalous westerly wind, occurring over the mid-latitude central-eastern Pacific past the date line is associated with the anomalous heating presenting both in the tropical central-eastern Pacific past the date line and the center of the North Pacific basin. Meanwhile, the STE anomaly appears around the region of the anomalous zonal wind. The fluctuation in jet strength shown in the second WPJS mode is strongly related to the heating anomaly in the Kuroshio Current region and the STE anomaly in the jet exit region. The third mode demonstrates a northward/southward shift of the WPJS, which has a statistical connection with a south-north dipolar pattern of the heating anomaly in the western North Pacific separated at 35°N. Meanwhile, the STE spatial displacement is in conjunction with jet shifts in the same direction. The heating anomaly has a close connection with the atmospheric circulation, and thus changes the mid-latitude baroclinicity, leading to the STE anomaly, which then reinforces the WPJS anomaly via internal atmospheric dynamics.

关键词： 200-hPa westerly jet stream surface heating anomaly atmospheric transient eddy anomaly

Relationship between the simulated East Asian westerly jet biases and seasonal evolu-tion of rainbelt over eastern China

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Chinese Science Bulletin 2005年第14期50卷 1503-1508页

作者： ZHANG Yaocun GUO Lanli Department of Atmospheric Sciences Institute of Severe Weather and Climate Nanjing University Nanjing 210093 China

A possible reason for the unreasonable simula- tion of maximum rainfall location, intensity and seasonal evolution over eastern China in CCM3 has been investigated. The analyses focus on the relationship between the simulated East Asian subtropical westerly jet biases and the seasonal evolution of rainbelt over eastern China. Comparisons of the simulated and observed precipitation distributions indicate that the simulated maximum rainfall location, intensity and seasonal evolution are inconsistent with reality. The simu- lated westerly jet center is located to the north of 40°N, which shifts eastward and northward and strengthens, com- pared with NCEP/NCAR reanalysis. The correlation analysis shows that there exists a significant positive correlation be- tween the maximum rainfall amount and zonal wind at 200 hPa over the Great Bend of the Huanghe River. Thus the simulated unrealistic heavy precipitation in the inland area of western China is related to the biases in the location and intensity of the East Asian subtropical westerly jet. Further analysis indicates that the temperature differences from south to north in the lower troposphere and the larger sensi- ble heating over the southeast Tibetan Plateau are responsi- ble for the westerly jet location and intensity biases. There- fore, much more attention should be paid to the accurate simulation of the surface heating near the Tibetan Plateau and the location and intensity of the East Asian subtropical westerly jet for the improvement of precipitation simulation over East Asia.

关键词：亚洲东部地区中国雨林地区数字模拟温度分布

Opposing Trends of Winter Cold Extremes over Eastern Eurasia and North America under Recent Arctic Warming

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Advances in Atmospheric Sciences 2020年第12期37卷 1417-1434页

作者： Shuangmei MA Congwen ZHU State Key Laboratory of severe weather and institute of climate System Chinese Academy of Meteorological SciencesBeijing 100081China

Under recent Arctic warming,boreal winters have witnessed severe cold surges over both Eurasia and North America,bringing about serious social and economic ***,we investigated the changes in daily surface air temperature(SAT)variability during the rapid Arctic warming period of 1988/89–2015/16,and found the daily SAT variance,mainly contributed by the sub-seasonal component,shows an increasing and decreasing trend over eastern Eurasia and North America,*** cold extremes(defined as days with daily SAT anomalies below 1.5 standard deviations)dominated the increase of the daily SAT variability over eastern Eurasia,while decreasing cold extremes dominated the decrease of the daily SAT variability over North *** circulation regime of cold extremes over eastern Eurasia(North America)is characterized by an enhanced high-pressure ridge over the Urals(Alaska)and surface Siberian(Canadian)*** data analyses and model simulations show the recent strengthening of the high-pressure ridge over the Urals was associated with warming of the Barents–Kara seas in the Arctic region,while the high-pressure ridge over Alaska was influenced by the offset effect of Arctic warming over the East Siberian–Chukchi seas and the Pacific decadal oscillation(PDO)–like sea surface temperature(SST)anomalies over the North *** transition of the PDO-like SST anomalies from a positive to negative phase cancelled the impact of Arctic warming,reduced the occurrence of extreme cold days,and possibly resulted in the decreasing trend of daily SAT variability in North *** multi-ensemble simulations of climate models confirmed the regional Arctic warming as the driver of the increasing SAT variance over eastern Eurasia and North America and the overwhelming effect of SST forcing on the decreasing SAT variance over North ***,the regional response of winter cold extremes at midlatitudes to the Arctic warming could be different due to the dis

关键词： daily surface air temperature variability extreme cold days Arctic warming eastern Eurasia North America

A New Method for Calculating the Wind Speed Distribution of a Moving Tropical Cyclone

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Advances in Atmospheric Sciences 2010年第1期27卷 69-79页

作者：胡邦辉杨修群谭言科王咏青范勇 institute of severe weather and climate Nanjing University institute of Meteorology PLA University of Science and Technology Nanjing University of Information Science and Technology

Based on gradient wind equations, including frictional force, and considering the effect of the movement of a tropical cyclone on wind speed, the Fujita Formula is improved and further simplified, and the numerical scheme for calculating the maximum wind speed radius and wind velocity distribution of a moving tropical cyclone is derived. In addition, the effect of frictional force on the internal structure of the tropical cyclone is discussed. By comparison with observational data, this numerical scheme demonstrates great advantages, i.e. it can not only describe the asymmetrical wind speed distribution of a tropical cyclone reasonably, but can also calculate the maximum wind speed in each direction within the typhoon domain much more accurately. Furthermore, the combination of calculated and analyzed wind speed distributions by the scheme is perfectly consistent with observations.

关键词： tropical cyclone maximum wind speed radius wind velocity distribution

Temporal Characteristics of Pacific Decadal Oscillation (PDO) and ENSO and Their Relationship Analyzed with Method of Empirical Mode Decomposition (EMD)

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Acta meteorologica Sinica 2005年第1期19卷 83-92页

作者：何卷雄余志豪杨修群 institute of severe weather and climate Nanjing University Nanjing 210093 Guangzhou Institute of Tropical and Oceanic Meteorology of CMA Guangzhou 510800 institute of severe weather and climate Nanjing University Nanjing 210093

Pacific Decadal Oscillation (PDO) is a long-term ENSO-like variability of theNorth Pacific. It is the first principal component of EOF of the North Pacific SST. ENSO is thestrongest signal of annular change of global climate system. Empirical Mode Decomposition (EMD)method is applied to two types of indices. One type of index is the Pacific Decadal Oscillation(PDO) index that represents a long-term ENSO-like variability of the North Pacific. The other typeof indices such as Southern Oscillation (SO) index, Ninol+2 SST, Nino3 SST, Nino4 SST and Nino3.4SST represents ENSO. The relationship between two types of indices shows the temporalcharacteristics and relationships between the two phenomena. It is found that, for PDO, the goodcorrelations with ENSO only exist on the quasi-2-7-yr timescales and decadal and multi-decadaltimescales, suggesting that a close relationship between PDO and ENSO only exists among some specialintrinsic mode functions at lower frequency band.

关键词： EMD(Empirical Mode Decomposition) intrinsic mode function PDO (PacificDecadal Oscillation) ENSO

Comparison of dust emissions, transport, and deposition between the Taklimakan Desert and Gobi Desert from 2007 to 2011

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Science China Earth Sciences 2017年第7期60卷 1338-1355页

作者： CHEN SiYu HUANG JianPing LI JingXin JIA Rui JIANG NanXuan KANG LiTai MA XiaoJun XIE TingTing Lanzhou University College of Atmospheric Sciences Chinese Academy of Meteorological Sciences Institute of Climate System (Polar Meteorology) State Key Laboratory of Severe Weather

The Taklimakan Desert(TD) and Gobi Desert(GD) are two of the most important dust sources in East Asia, and have important impact on energy budgets, ecosystems and water cycles at regional and even global scales. To investigate the contribution of the TD and the GD to dust concentrations in East Asia as a whole, dust emissions, transport, and deposition over the TD and the GD in different seasons from 2007 to 2011 were systematically compared, based on the weather Research and Forecasting model coupled with Chemistry(WRF-Chem). Dust emissions, uplift, and long-range transport related to these two dust source regions were markedly different due to differences in topography, elevation, thermal conditions, and atmospheric circulation. Specifically,the topography of the GD is relatively flat, and at a high elevation, and the area is under the influence of two jet streams at high altitudes, resulting in high wind speeds in the upper atmosphere. Deep convective mixing enables the descending branch of jet streams to continuously transport momentum downward to the mid-troposphere, leading to enhanced wind speeds in the lower troposphere over the GD which favors the vertical uplift of the GD dust particles. Therefore, the GD dust was very likely to be transported under the effect of strong westerly jets, and thus played the most important role in contributing to dust concentrations in East Asia. Approximately 35% and 31% of dust emitted from the GD transported to remote areas in East Asia in spring and summer, respectively. The TD has the highest dust emission capabilities in East Asia, with emissions of about 70.54 Tg yr.1 in spring, accounting for 42% of the total dust emissions in East Asia. However, the TD is located in the Tarim Basin and surrounded by mountains on three sides. Furthermore, the dominant surface wind direction is eastward and the average wind speed at high altitudes is relatively small over the TD. As a result, the TD dust particles are not easily transpo

关键词： East Asian dust WRF-Chem model Taklimakan Desert Dust Gobi Desert Dust Dust emissions Dust transport Dust deposition

INTERANNUAL VARIATION CHARACTERISTICS OF EAST HEMISPHERIC CROSS-EQUATORIAL FLOW AND ITS CONCURRENT RELATIONSHIPS WITH TEMPERATURE AND RAINFALL IN CHINA

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Journal of Tropical Meteorology 2008年第2期14卷 97-100页

作者：雷小春杨修群 institute of severe weather and climate Nanjing University

The NCEP/NCAR global reanalysis data were used to analyze the interannual variation characteristics of the cross-equatorial flow (CEF) and its concurrent relationships with temperature and rainfall in China. The results indicated that CEF changes more in summer than in winter. As the main flow channel in summer, the Somali CEF changes in a way that does not markedly influence the changes in the CEF total except for winter. The summer CEF total has two sudden increases and one sudden decrease during the last century while the winter total has just one decrease. Long-period data show that the correlation between CEF and summer rainfall in China is not very significant, but is different before and after the 1970s, which is due to CEF's close links with the East Asia summer monsoon. Winter CEF's correlation with concurrent winter temperature in northern and southern China varies with the relationship between CEF and sea-level pressure in different areas.

关键词： cross-equatorial flow (CEF) interannual variation characteristics rainfall temperature correlation

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