全球大气气候异常位势高度场的时空结构分析

用半球气候异常场强度（Ia）及球函数分析改进方案，分析了NCEP／NCAR再分析项目的全球40年月平均气候异常高度场的时空结构，并分析了对流层下、上部半球平均气温异常的年际变化，结果表明，全球Ia存在明显的时（季节）空（高度、半球）差异；构造出三组参数高度概括地给出地球大气位势高度场异常环流球函数谱结构的基本特点；通过球函数展开的某些系数与半球500hPa等压面平均高度异常成正比，也近似与大气下半部（半球）平均温度成正比，揭示出不同层次大气平均温度异常的年际变化及其与热带海洋SSTA的关系。

对流层大气温度“蝴蝶形”震前异常

利用美国国家和海洋大气管理局（NOAA）的大气温度数据，分析陆地地震和海洋地震震前震中上空的大气温度变化，研究其作为地震短临前兆的可能性.地震样本包括2014年2月12日于田Ms7.3地震、2008年5月12日汶川Ms8.0地震、2011年3月11日日本Ms9.0地震、2014年4月1日智利Ms8.1海洋地震、2013年3月27日台湾南投县Ms6.1地震和2014年5月30日云南盈江Ms6.1地震.结果表明：（1）震前，震中位置300-1000hPa大气温度有较为一致的变化趋势；（2）200hPa与400hPa处（根据不同地点可选择其他，诸如350hPa、300hPa等高度数据）温度折线图在震前趋近或者相交，出现类似蝴蝶翅膀的“蝴蝶形”特殊曲线形状；（3）200hPa与400hPa温度差等值线图在（震前数月、数周或数天不等）震中附近区域的数值减小，温度差等值线图的塌陷最低点对应震中位置.以上规律有望应用于地震短临预测的时间与震中的确定.

Perturbed Solving Method for Interdecadal Sea-air Oscillator Model

A coupled system of the interdecadal sea-air oscillator model is studied. The E1 Nifio-southem oscillation （ENSO） atmospheric physics oscillation is an abnormal phenomenon involved in the tropical Pacific ocean-atmosphere interactions. The oscillator model is involved with the variations of both the eastern and western Pacific anomaly pat- terns. This paper proposes an ENSO atmospheric physics model using a method of the perturbation theory. The aim is to create an asymptotic solving method for the ENSO model. Employing the perturbed method, the asymptotic solution of corresponding problem is obtained, and the asymptotic behaviour of the solution is studied. Thus we can obtain the prognoses of the sea surface temperature anomaly and related physical quantities.

Characteristics of Tropical Sea Surface Temperature Anomalies and Their Influences on the Onset of South China Sea Summer Monsoon

The characteristics of sea surface temperature anomalies （SSTAs） in the tropical oceans and their influences on the onset of South China Sea summer monsoon （SCSSM） have been studied.The anomaly of SST in tropical Pacific Ocean exerts persistence impact for one to three months on atmospheric circulations.If the warm pool becomes anomalously warmer during an earlier period from February to April,the SCSSM breaks out earlier,and vice versa.Singular value decomposition （SVD） and composite analysis have shown that,in La Ni（n）a pattern,the convection over Western Pacific will occur earlier and be stronger than normal,which favors the convergence at a lower layer over Western Pacific,as well as the strengthening of upwelling branch of Walker circulation,leading to an earlier burst of westerly in the southern South China Sea.Moreover,the convection in Sumatra appears earlier than normal and favors the westerly evolution in eastern Indian Ocean,resulting in the splitting of the subtropical high belt and an early onset of SCSSM.However,the atmospheric circulation anomaly is reversed in El Ni（n）o pattern.

INTERANNUAL VARIATIONS OF ATMOSPHERIC HEAT SOURCES AND MOISTURE SINKS OVER THE EQUATORIAL PACIFIC AND THEIR RELATIONS TO THE SST ANOMALIES

The interannual variations of atmospheric heat sources and moisture sinks over the Equatorial Pacific and their relations with the SST anomalies are studied using ECMWF reanalysis data from 1979 to 1993. It is found by singular value decomposition (SVD) analysis that the region in the tropical Pacific with high positive correlation between the vertically integrated heat source <Q1> anomaly and the SST anomaly, and between the vertically integrated moisture sink <Q2> anomaly and the SST anomaly, is mainly located in a long and narrow belt to the east of 170 °E between 5 °S and 5 °N. The analysis of the vertical structure of atmospheric heat sources and moisture sinks shows that the interannual variations of Q1, Q2 and SST in the equatorial central and eastern Pacific are strongly and positively correlated in the whole troposphere except the bottom (962.5 hPa) and the top (85 hPa) layers. However, in the western Pacific, the interannual variations of Q1 below 850 hPa is negatively related to the SST. The correlation coefficient at the level 962.5 hPa reaches even –0.59. In other layers the positive correlation between the interannual variations of Q1, Q2 and the SST are weak in the western Pacific.

ENSO Signals in Tropospheric Temperature Simulated by an AGCM GAMIL

Using reanalysis data as a benchmark, the authors evaluate the performance of an Atmospheric General Circulation Model （AGCM） named GAMIL （Grid-point Atmospheric Model of LASG/IAP）. GAMIL is used to simulate the tropospheric temperature anoma- lies associated with the El Nifio-Southern Oscillation （ENSO） in boreal winters for the period 1980-99. The results show that the symmetrical components of tem- perature anomalies simulated by GAMIL closely resem- ble those in the reanalysis data in spatial patterns, espe- cially in the Northern Hemisphere. The limitation of the model is that the simulated cold anomaly over South Asia is located to the east of the reanalysis. The observed tem- perature anomalies in the South Pacific and the high lati- tudes of the Southern Hemisphere are not evident in the simulation. The maximum value is 0.8 K smaller and the minimum value is -0.4 K smaller than the reanalysis. The difference between the simulation and the reanalysis is more evident in the regional features of the asymmetrical components of the temperature anomalies. Our results demonstrate that the previously discovered weak response of the GAMIL model to specified sea surface temperature forcing is dominated by the symmetric （asymmetric） component in the tropics （extra-tropics）.

The Anomalous European Climates Linked to Different Euro-Atlantic Blocking

The impact on temperature and precipitation anomalies over the European continent of the different action centers of blocking events in the Euro-Atlantic sector was investigated. It was found that the position of the blocking action center in the Euro-Atlantic region seems to dominate European climates. When the center of the blocking action is in the Greenland region, there is a strong negative temperature anomaly over Central and Northern Europe, as well as a strong positive precipitation anomaly over southern Europe. However, there tends to be a strong negative temperature anomaly in the west(east) part of Europe when the center of the blocking action is shifted to the Eastern Atlantic and west Europe(east Europe). In particular, when the blocking action center is closer to the European continent, the fall in temperature becomes more evident over Central and south Europe than over other regions. Moreover, it was found that when the region where the blocking action center exists changes from the Eastern Atlantic and west Europe region to the east Europe region, the existing region of dominant positive precipitation anomalies varies from southwest Europe to southeast Europe and the Middle East.

Atmospheric eddy anomalies associated with the wintertime North Pacific subtropical front strength and their influences on the seasonal-mean atmosphere

This study investigates transient eddy activity anomalies in the mid-latitude upper troposphere associated with intensity variability of the wintertime North Pacific subtropical front. Our results show that the meridional gradient of air temperature and baroclinic instability in the mid-latitude atmosphere become stronger as the subtropical front intensifies, and the mid-latitude westerly jet accelerates with barotropic structure. We further divide the mid-latitude atmospheric eddy activities into high-(2–7 days) and low-frequency(10–90 days) eddy activities according to their life periods. We find that, when the oceanic subtropical front intensifies, the high-frequency atmospheric eddy activity in the mid-latitudes strengthens while the low-frequency eddy activity weakens. The stronger high-frequency eddy activity tends to moderate the air temperature gradient and baroclinicity in the mid-latitudes. High-frequency eddy anomalies accelerate the westerly jet on the northern side and downstream of the westerly jet, and enhance the jet with equivalent barotropic structure. In contrast, the weaker low-frequency eddy activity has a negative contribution to zonal wind speed tendency and attenuates the zonal homogenization of the jet. The anomalous thermodynamic forcing of the low-frequency eddy activity helps maintain the meridional gradient of air temperature in the mid-troposphere.

Impact of El Nio on atmospheric circulations over East Asia and rainfall in China： Role of the anomalous western North Pacific anticyclone

This paper presents a review on the impact of El Nio on the interannual variability of atmospheric circulations over East Asia and rainfall in China through the anomalous anticyclone over western North Pacific(WNPAC). It explains the formation mechanisms of the WNPAC and physical processes by which the WNPAC affects the rainfall in China. During the mature phase of El Nio, the convective cooling anomalies over western tropical Pacific caused by the weakened convections trigger up an atmospheric Rossby wave response, resulting in the generation of the WNPAC. The WNPAC can persist from the winter when the El Nio is in its peak to subsequent summer, which is maintained by multiple factors including the sustained presence of convective cooling anomalies and the local air-sea interaction over western tropical Pacific, and the persistence of sea surface temperature anomalies(SSTA) in tropical Indian and tropical North Atlantic. The WNPAC can influence the atmospheric circulations over East Asia and rainfall in China not only simultaneously, but also in the subsequent summer after an El Nio year, leading to more rainfall over southern China. The current paper also points out that significant anomalies of atmospheric circulations over East Asia and rainfall over southern China occur in El Nio winter but not in La Nio winter, suggesting that El Nio and La Nio have an asymmetric effect. Other issues, including the impact of El Nio diversity and its impact as well as the relations of the factors affecting the persistence of the WNPAC with summer rainfall anomalies in China, are also discussed. At the end of this paper some issues calling for further investigation are discussed.

Arctic Oscillation anomaly in winter 2009/2010 and its impacts on weather and climate

Using the Arctic Oscillation(AO) index,the exceptional winter(DJF) of 2009 has been analyzed.The middle-to-high latitudes of the Northern Hemisphere suffered from a nearly zonally symmetric anomaly of temperature and pressure.This situation revealed that two negative AO events occurred in the winter of 2009/2010,with unprecedented low values in January 2009 and February 2010.The negative AO event in January 2009 can be further divided into two stages:the first stage was mainly driven by enhanced upward-propagating planetary waves,which led to a weak stratospheric polar vortex associated with a downward-propagating negative AO signal;the second stage was caused by a lower tropospheric positive temperature anomaly in the high latitudes,which maintained the positive geopotential height anomaly of the first stage.The two successively occurring stages interacted and caused the lower troposphere to experience a strong and lengthy persistence of the negative AO event.We consider that the second event of negative AO in February 2010 is related to the downward-propagating negative AO after sudden stratospheric warming.Eleven long-persistence negative AO events were analyzed using reanalysis data.The results suggest that the negative AO in the troposphere might have been caused by stratospheric sudden warming,a downward-propagating weak stratospheric circulation anomaly or dynamic processes in the troposphere.Further study shows that the negative phase of the AO in the winter of 2009/2010 corresponded to a wide range of temperature and precipitation anomalies in the Northern Hemisphere.Therefore,to improve the accuracy of weather forecasting and climate prediction,more attention should be paid to the AO anomaly and its impact.