中国东部夏季降水与同期东亚副热带急流年代际异常的关系   总被引：10，自引：1，他引：9       下载免费PDF全文

孙凤华  张耀存  郭兰丽 《高原气象》2009,28(6):1308-1315

利用中国738个台站的降水观测资料和NCEP/NCAR再分析资料, 分析了我国降水和200 hPa东亚副热带西风急流轴的年代际变化特征, 揭示了东亚副热带西风急流位置的南北移动与我国长江流域和华北降水异常之间的联系。结果表明, 我国东部地区夏季（7、 8月）降水异常主要表现为长江中下游地区多（少）雨, 华北及华南地区少（多）雨, 20世纪70年代末80年代初是这种异常分布型发生转折的时间。与此同时, 东亚高空副热带急流轴位置从70年代末开始逐渐偏南, 急流轴位置的变动将引起对流层低层水汽辐合区和高层散度分布以及垂直环流相应的变化, 进而引起降水区域的变化。相关分析发现, 当急流位置偏南时, 25°~35°N西风增强, 42°~50°N西风减弱, 华北夏季降水减少, 长江中下游地区夏季降水增多; 反之, 当急流位置偏北时, 华北夏季降水增多, 长江中下游地区夏季降水减少。与70年代末开始的我国东部地区急流轴位置逐渐南移相对应, 华北地区夏季降水呈现逐渐减少、 长江中下游地区夏季降水呈现逐渐增多的变化趋势。分析低层水汽通量和高层的散度分布以及垂直环流的差异发现, 1980年以来华北地区对流层中低层水汽通量辐合减弱, 水汽供应减少, 垂直上升运动减弱, 造成了华北夏季降水减少, 而长江中下游地区水汽通量辐合增加, 水汽供应增多, 垂直上升运动增强, 导致该地区降水增加。  相似文献   

陆面过程模式CoLM和NCAR_CLM3.0对中国典型森林生态系统陆气相互作用的模拟Ⅰ.不同模式模拟结果的初步分析     

宋耀明  郭维栋  张耀存  陈永立 《气候与环境研究》2009,14(3)

量为期1年的日均值的模拟为例,COLM和CLM3.0在长白山观测站模拟值和观测值时间序列的相关系数分别为0.80和0.65,在千烟洲站分别为0.69和0.64,均通过了0.01的信度检验;两个模式对全年平均的模拟与观测日平均值的比值在长白山分别为1.21和0.86,在千烟洲分别为0.83和0.60.研究结果表明,这两个陆面过程模式可以作为研究这两种典型森林生态系统陆气交换的基本工具.同时,对模式模拟性能差异的深入分析将有助于进一步改进陆面模式的参数化过程,为相关研究奠定更坚实的基础.  相似文献   

我国东部地区夏季不同等级降水日数     

艾卉  张耀存  卢伟 《气象科学》2009,(3):299-306

用全国1958—2004年逐日降水资料,分析我国东部地区夏季总降水日数以及不同等级降水日数的年代际变化特征,结果表明,1980—2004年与1958—1979年两个时段相比,我国东部各地区夏季总降水日数和不同等级降水日数具有明显不同的变化特征。东北地区总降水日数和总降水量减少,这主要与小雨日数减少有关。华北地区总雨日数和总降水量也呈减少特征,总雨日数减少是由于各等级雨日数减少引起,且小雨日数减少贡献较大,而总降水量减少却主要是由于暴雨日数的减少引起。长江流域总降水日数和总降水量增加,总雨日数增多主要与中雨以上级别雨日数的增多有关,而总降水量的增加主要与暴雨日数增加有关。华南地区总雨日数和总降水量减少,总雨日数减少主要与小雨日数减少有关,而总降水量减少是由于各等级降水日数减少引起。  相似文献   

东亚副热带西风急流位置变化与亚洲夏季风爆发的关系   总被引：1，自引：0，他引：1  

张耀存  况雪源 《湖北气象》2008,27(2):97-103

利用1961～2000年的NCEP/NCAR候平均再分析资料,初步探讨了季节转换期间东亚副热带西风急流南北和东西向位置变化与亚洲季风爆发之间的联系。结果表明,亚洲夏季风爆发伴随着东亚副热带西风急流轴线的北跳和急流中心西移,急流轴北跳至35°N以北的青藏高原上空,南支西风急流消失,亚洲季风环流形势建立。南海季风爆发早年,低纬的东风向北推进的时间早,到达的纬度偏北,中纬的西风急流强度偏弱,季风爆发晚年则相反。同时,南海夏季风爆发早年,青藏高原上空急流核出现较早,西太平洋上空急流核减弱较快,急流中心“西移”较早。而在南海夏季风爆发晚年,西太平洋上空的急流核减弱较迟,青藏高原上空急流核形成偏晚,急流中心“西移”较迟。此外,急流中心东西向位置和强度变化与江淮流域梅雨的开始和结束也有密切关系。  相似文献   

区域气候模式对中国沙尘天气气候特征的模拟研究   总被引：1，自引：0，他引：1  

黄乾  姚素香  张耀存 《中国沙漠》2012,32(1):188-197

现有的沙尘天气数值预报模式多选用中尺度天气模式单向耦合起沙模式的方式,不适合用来模拟沙尘气溶胶的长距离输送过程,也无法研究沙尘气溶胶辐射效应对气象场的反馈及气候变化的影响。利用一个耦合沙尘模式的高分辨率区域气候模式,模拟了2001年中国北方沙尘天气爆发的时空分布特征。模拟结果与站点观测结果对比发现,模式能够较好地模拟出中国北方主要的沙尘源地分布及沙尘天气爆发的季节变率。分析不同粒径沙尘颗粒的垂直分布特征发现,沙源地表土壤粒子特征、地形对起沙颗粒的大小都有影响;直径超过5 μm的大粒子是北方沙尘天气的主要成分,而影响长江以南的沙尘天气主要以1 μm以下的小粒子为主。对沙尘传输路径的模拟结果和实况观测发现,来自于不同沙源的沙尘天气其影响的范围有显著差异,模式能够较好地模拟出中国主要沙尘传输路径。  相似文献   

东北气候和生态过渡区近50年来降水和温度概率分布特征变化   总被引：18，自引：11，他引：7  

张耀存  张录军 《地理科学》2005,25(5):561-566

文章从中国160个站的观测资料中选取位于东北气候和生态过渡区内9个测站的冬、夏季降水和温度资料,分析该地区近50年来冬夏季降水和温度的年际变化及其概率分布特征,结果表明,东北气候和生态过渡区的冬夏季降水和温度有明显的年代际变化特征,在不同的年代际变化阶段,降水和温度的总体概率分布特征差异较大,这种概率分布形式的差异与高温、干旱等极端天气气候事件的频繁发生具有密切关系。20世纪80年代以来降水处于平均值减小的总体分布中,温度则处于平均值增加的总体分布中,因此该地区冬季发生暖冬和少雨(雪)的机会增大,夏季出现严重干旱和高温的可能性增大。  相似文献   

SIMULATION OF SUMMER CLIMATE IN CHINA DURING 1997 AND 1998 USING A REGIONAL AIR-SEA COUPLED MODEL     

姚素香  黄乾  张耀存 《热带气象学报(英文版)》2013,19(1):80-86

Using the regional air-sea coupled climate model RegCM3-POM,a series of numerical experiments are performed to simulate the summer climate in 1997 and 1998 with different coupling time steps.The results show that the coupled model has good performance on the simulation of the summer sea surface temperature(SST) in 1997 and 1998,and the simulation results of CPL1(with the coupling time step at 1 hour) are similar to those of CPL6(with the coupling time step at 6 hours).The coupled model can well simulate SST differences between 1997 and 1998.As for the simulation of the drought in 1997 and the flood in 1998,the results of CPL6 are more accurate.The coupled model can well simulate the drought in 1997 over North China,and compared with the results of the atmosphere model RegCM3,the simulation ability of the coupled model is improved.The coupling model has better ability in the simulation of the circulation in the middle and low levels,and the water vapor transportation in the coupling model is reasonable in both 1997 and 1998.RegCM3(an uncoupled model) cannot correctly simulate the transportation path differences between 1997 and 1998,but the coupled model can simulate the differences well.  相似文献   

BCC_AGCM2.0.1模式系统对江淮梅雨期降水的模拟能力   总被引：2，自引：0，他引：2  

沈瑱  张耀存  肖卉  周孝评 《气象》2011,37(11):1336-1342

文章通过累积频率方法定义江淮地区观测和模拟的梅雨期,分析国家气候中心大气模式BCC_AGCM2.0.1对我国东部地区暴雨、大雨、中雨和小雨四种等级降水的模拟能力。由于模式的模拟环流背景与实际不同,导致模拟的降水峰值时期与梅雨期有偏差,因此通过累积频率方法定义模拟的梅雨期,模拟梅雨期为6月1候至6月3候,而实际观测梅雨期6月5候至7月2候,模拟期较实际梅雨期提前了20天。模拟结果表明模拟的我国东部总降水量偏少,总雨日数偏多,主要是由于模拟的暴雨日数偏少,小雨日数偏多;观测的江淮地区近40年来暴雨、大雨和中雨呈上升趋势,小雨呈下降趋势,模式模拟的不同等级降水变化趋势与观测相反,暴雨、大雨和中雨呈下降趋势,小雨呈上升趋势。  相似文献   

Simulation of the westerly jet axis in boreal winter by the climate system model FGOALS-g2     

肖楚良  张耀存 《大气科学进展》2013,30(3):754-765

The major features of the westerly jets in boreal winter, consisting of the Middle East jet stream (MEJS), East Asian jet stream (EAJS) and North Atlantic jet stream (NAJS), simulated by a newly developed climate system model, were evaluated with an emphasis on the meridional location of the westerly jet axis (WJA). The model was found to exhibit fairly good performance in simulating the EAJS and NAJS, whereas the MEJS was much weaker and indistinguishable in the model. Compared with the intensity bias, the southward shift of the WJA seems to be a more remarkable deficiency. From the perspective of Ertel potential vorticity, the profiles along different westerly jet cores in the model were similar with those in the reanalysis but all shifted southward, indicating an equatorward displacement of the dynamic tropopause and associated climatology. Diagnosis of the thermodynamic equation revealed that the model produced an overall stronger heating source and the streamfunction quantifying the convection and overturning Hadley circulation shifted southward significantly in the middle and upper troposphere. The two maximum centers of eddy kinetic energy, corresponding to the EAJS and NAJS, were reproduced, whereas they all shifted southwards with a much reduced intensity. A lack of transient eddy activity will reduce the efficiency of poleward heat transport, which may partially contribute to the meridionally non-uniform cooling in the middle and upper troposphere. As the WJA is closely related to the location of the Hadley cell, tropopause and transient eddy activity, the accurate simulation of westerly jets will greatly improve the atmospheric general circulation and associated climatology in the model.  相似文献   

THE FEATURES OF EAST ASIAN JET STREAM IN PERSISTENT SNOWSTORM AND FREEZING RAIN PROCESSES OVER SOUTHERN CHINA IN EARLY 2008     

张春艳  张耀存 《热带气象学报(英文版)》2014,20(4):349-359

Based on the National Centers for Environmental Prediction and National Center for Atmospheric Research (NCEP/NCAR) daily reanalysis data and the upper-level objective analysis data provided by the Meteorological Information Comprehensive Analysis and Process System (MICAPS), the feature of the spatio-temporal variation of the East Asian jet stream (EAJS) in persistent snowstorm and freezing rain processes over southern China in January 2008 have been investigated. Each of the storm events was closely linked with the extraordinarily abnormal variations of East Asian subtropical jet (EASJ) and East Asian polar front jet (EAPJ) at that time. The stronger EASJ with abnormally northward position of the jet axis corresponded to the more intense storm event with broader ranges and longer duration time. The heavy freezing-rain-and-snow event occurred over the region where a strong southerly wind of EASJ prevailed. Meanwhile, the westerly and northerly winds of the EAPJ were significantly intensified, which were also closely related to the beginning, enhancement, and ending of the heavy snowfall. The meridional component of the EAPJ was dominated by the northerly wind during the snowstorm. Thus, the intensification of the snowstorm was attributed to both the strengthening of the meridional wind of EAPJ and the southerly wind of EASJ. Further analysis indicated that wind speed and the zonal wind of the two jets exhibited precursory signals about half a month prior to this extreme event, and the precursory signals were found in the meridional components of the two jets about 20 days preceding the event. The sudden weakening of the meridional component of EASJ and the zonal component of EAPJ signified the ending of this persistent snowstorm.  相似文献