青海湖地区植被覆盖及其与气温降水变化的关系

使用1981年到2003年月NDVI(归一化植被指数）资料,计算了青海湖地区植被覆盖度,分析了该地区植被覆盖度的历史演变,发现其值在增大,尤其是从1996到2003年,青海湖地区的植被覆盖度都为正距平,NDVI年平均增长率为1.07×10-3。四季的植被覆盖度均为增加趋势,夏季增加最多。月平均温度与月植被覆盖度、春夏季降水与夏秋季植被覆盖度显著正相关。因此,热量条件和春夏季降水是影响青海湖地区植被生长的关键性因素。     

夏季青藏高原与热带西太平洋下垫面热源异常对中国短期气候的影响

本文利用一个两层全球大气环流格点模式进行了控制试验、青藏高原地表反照率增加及热带西太平洋海温升高等三个数值试验,以研究夏季这两个地区下垫面热源异常对短期气候变化的影响。结果表明,高原地面热源减弱将造成海平面气压场上亚洲大陆低压减弱;高原及其以西地区500 hPa高度下降,黄河以北地区高度升高;同时高原地区、江淮流域以及黑龙江流域降水减少,但从北疆、内蒙到辽河流域以及我国西南局部和东南沿海地区降水增加。热带西太平洋海温异常带来的变化与此不同.文中还就下垫面热源异常在短期气候预测方面的可能应用等问题进行了讨论。     

2016年6月23日江苏阜宁龙卷的高分辨快速更新同化预报与分析1

基于3 km水平分辨率的第二代华东快速更新循环同化预报模式系统,对2016年6月23日江苏阜宁龙卷个例预报结果进行了分析,通过螺旋度的时间演变等讨论了龙卷母体—对流单体的发展过程,并对比了有无同化的预报结果。结果表明,快速更新循环同化系统在阜宁附近模拟出了类似龙卷母体的涡旋结构,同时伴随有剧烈的上升运动,模拟的发生时间与发展过程与实况基本吻合。但模拟的涡旋发生在江苏阜宁北侧,与观测相比偏差20多公里,且最大地面风速较实况小。进一步分析表明,该对流单体从中层上升运动开始,随着上升区向上和向下发展,首先在中高空出现剧烈的上升运动,z螺旋度增大,高层辐散加强,x螺旋度增大,随后中低空的垂直运动也增强,y螺旋度增大,低层辐合增强,最后随着高层辐散和垂直运动的减弱,低层涡旋减弱并消散。北京时间14:00没有进行观测资料同化预报结果中,在阜宁附近没有预报出类似的对流单体,表明逐小时循环同化对此次龙卷天气的模拟起着关键作用。     

DIURNAL VARIATIONS OF SUMMER PRECIPITATION IN SHANGHAI

This paper investigates the diurnal variations of summer precipitation in Shanghai by using the city''s hourly precipitation data over a span of 35 years. The result shows that the precipitation peaks twice, in the morning and in the afternoon. Precipitation in the morning is characterized by light to moderate rain, and that in the afternoon by heavy to super heavy rain. The peak of short-duration precipitation is mostly found in the afternoon and at dusk, and that of long-duration precipitation in the morning. Most of the precipitation events in Shanghai are of a short duration of 2-3 hours. Basically, the precipitation is spatially distributed in three areas: the eastern coastal and central urban area, where the precipitation peaks mostly in the afternoon, the southern coastal area, where the precipitation peaks both in the afternoon and during the night, and the western area, where long-duration precipitation accounts for a much larger proportion than the other two areas.     

南亚高压流型转换的Eliassen-Palm通量特征

一、问题的提出 根据南亚高压的中心位置,可将其分为西部型和东部型。南亚高压流型转换,是指南压高压初夏移上青藏高原以后,西部型和东部型间的相互转换过程。南亚高压的这种流型转换,以盛夏7—8月最明显。 南亚高压流型转换与我国大范围天气变化有着十分密切的关系,所以关于这方面的研究工作(包括天气气候、动力分析、数值模拟等)颇多,     

Impacts of SST anomalies in the Indian-Pacific basin on Northwest Pacific tropical cyclone activities during three super El Ni?o years

This study investigated the impact of sea surface temperature(SST)in several important areas of the Indian-Pacific basin on tropical cyclone(TC)activity over the western North Pacific(WNP)during the developing years of three super El Ni?o events(1982,1997,and 2015)based on observations and numerical simulations.During the super El Ni?o years,TC intensity was enhanced considerably,TC days increased,TC tracks mostly recurved along the coasts,and fewer TCs made landfall in China.These characteristics are similar to the strong ENSO-TC relationship but further above the climatological means than in strong El Ni?o years.It indicates that super El Ni?o events play a dominant role in the intensities and tracks of WNP TCs.However,there were clear differences in both numbers and positions of TC genesis among the different super El Ni?o years.These features could be attributed to the collective impact of SST anomalies(SSTAs)in the tropical central-eastern Pacific and East Indian Ocean(EIO)and the SST gradient(SSTG)between the southwestern Pacific and the western Pacific warm pool.During 2015,the EIO SSTA was extremely warm and the anomalous anticyclone in the western WNP was enhanced,resulting in fewer TCs than normal.In 1982,the EIO SSTA and spring SSTG showed negative anomalies,followed by an increased anomalous cyclone in the western WNP and equatorial vertical wind shear.This intensified the conversion of eddy kinetic energy from large-scale flows,favorable for the westward shift of TC genesis.Consequently,anomalous TC activities during the super El Ni?o years resulted mainly from combined SSTA impacts of different key areas over the Indian-Pacific basin.     

区域气候模式RegCM3在华东地区夏季的10年回报和2010年业务预报

利用国家气候中心全球海气耦合模式(BCC_CM1.0)嵌套区域气候模式RegCM3进行了近10年(1998-2007年)夏季回报及2010年华东夏季实时业务预报。从10年回报的模拟平均状况来看,模式基本能反映出中国东部夏季的平均状况,模式回报的夏季气温分布与实况较为相似,但回报的夏季降水量分布形态与实况有一定差异。使用国家气候中心六级Ps评分及简化的Ps评分对模式10年回报进行了评估。结果表明,该模式对华东地区夏季气温和降水有一定的跨季度预报能力,温度和降水10年平均Ps评分分别为69.9和60.9;对华东地区南部的气温及其东南部的降水有较好的回报效果。利用该模式进行了2010年夏季实时业务预报,预报检验表明,模式预报的2010年夏季温度距平和降水距平百分率分布与实况较为一致,夏季温度和降水的Ps评分分别为71.4和55.3;对影响较为严重的气候事件如江西降水极端偏多等也进行了准确预报。     

ASSIMILATION OF REAL OBSERVATIONAL DATA WITH THE GSI-HYBRID DATA ASSIMILATION SYSTEM TO IMPROVE TYPHOON FORECAST

A hybrid GSI (Grid-point Statistical Interpolation)-ETKF (Ensemble Transform Kalman Filter) data assimilation system has been recently developed for the WRF (Weather Research and Forecasting) model and tested with simulated observations for tropical cyclone (TC) forecast. This system is based on the existing GSI but with ensemble background information incorporated. As a follow-up, this work extends the new system to assimilate real observations to further understand the hybrid scheme. As a first effort to explore the system with real observations, relatively coarse grid resolution (27 km) is used. A case study of typhoon Muifa (2011) is performed to assimilate real observations including conventional in-situ and satellite data. The hybrid system with flow-dependent ensemble covariance shows significant improvements with respect to track forecast compared to the standard GSI system which in theory is three dimensional variational analysis (3DVAR). By comparing the analyses, analysis increments and forecasts, the hybrid system is found to be potentially able to recognize the existence of TC vortex, adjust its position systematically, better describe the asymmetric structure of typhoon Muifa and maintain the dynamic and thermodynamic balance in typhoon initial field. In addition, a cold-start hybrid approach by using the global ensembles to provide flow-dependent error is tested and similar results are revealed with those from cycled GSI-ETKF approach.     

华东地区气温变化对居住建筑能源消耗的影响研究

基于1961-2007年华东478个测站和2010-2039年RegCM3模式模拟的日平均气温资料,分析了华东采暖度日和制冷度日时空变化特征及其与气温变化的关系。结果表明,1961-2007年期间,华东采暖度日呈先增加后减少的变化趋势,制冷度日则呈先减少后增加的变化趋势。在2010-2039年期间,华东采暖度日将继续减...     

National Basic Research Program of China(973 Program) Indo-Pacific Oceanic Channel Project Special Issue

正1 INTRODUCTION The tropical Indo-Pacific Oceans span over twothirds of the global tropical oceans.A major warm pool with the highest large-scale sea surface temperature of the global oceans is located in the western Pacific and eastern Indian Oceans.The climate systems over the tropical Pacific and Indian Oceans are subject to strong ocean-atmosphere coupling at multiple scales from intraseasonal to interannual,and to centennial.The strongest