山西北中部一次秋季连阴雨过程分析

2009年9月4—10日,山西省北中部出现了一次持续时间长、降水强度大、落区范围广的连阴雨天气过程,致使气温持续偏低、日照偏少,给工农业生产、交通运输和人民生活造成严重影响。该文对这次天气过程的大气环流、西风急流等主要影响系统进行重点分析,对各种物理量场进行诊断,初步揭示了此次连阴雨过程的成因和降水特征。     

大气热源30～60天振荡与华南6月旱涝的关系

利用1958—2000年NCEP/NCAR再分析资料和华南测站降水资料,分析了大气热源30～60 d振荡对华南6月旱涝的影响。结果表明,在涝(旱)年对流层低层,南海至日本东南面的西北太平洋(WNP)是一个异常的低频反气旋(气旋),伴随有异常的低频热汇(热源)区,华南至日本南部存在一个异常气旋(反气旋),对应于异常的低频热源(热汇)区,华南地区低层异常辐合(辐散);平均而言,旱年华南5—6月30～60 d振荡的位相演变要比涝年的偏晚约7～11天;涝年,低频热源和气旋从南海南部北传和从西太平洋暖池区西北传,以及从140°E附近WNP的西传都十分明显,它们对华南6月降水偏多有非常重要的影响。而旱年南海及邻近区域的低频热源和气旋北传较涝年偏晚,WNP上低频热源的西伸不明显。前期南海低频热源推进的迟早以及热带WNP上的低频热源是否西传对华南6月的降水有显著影响。     

浅谈下垫面性质对乌兰察布市气温地理分布的影响

太阳辐射、大气环流和下垫面性质（如水、陆、地形、土壤、植被等）是形成和影响气候变化的主要原因,它们相互联系,综合影响,其中起主要作用的因子是太阳辐射,但地形地理在一定的条件下对太阳辐射和大气环流起到一定的制约作用,使某些要素改变了原来的分布规律,乌兰察布市的气温、降水等气候要素分布,就是下垫面在其中起了主要作用。     

Trends in graded precipitation in China from 1961 to 2000

Daily precipitation rates observed at 576 stations in China from 1961 to 2000 were classified into six grades of intensity, including trace （no amount）, slight （≤ 1 mm d^-1）, small, large, heavy, and very heavy. The last four grades together constitute the so called effective precipitation （〉 1 mm d^-1）. The spatial distribution and temporal trend of the graded precipitation days are examined. A decreasing trend in trace precipitation days is observed for the whole of China, except at several sites in the south of the middle section of the Yangtze River, while a decreasing trend in slight precipitation days only appears in eastern China. The decreasing trend and interannual variability of trace precipitation days is consistent with the warming trend and corresponding temperature variability in China for the same period, indicating a possible role played by increased surface air temperature in cloud formation processes. For the effective precipitation days, a decreasing trend is observed along the Yellow River valley and for the middle reaches of the Yangtze River and Southwest China, while an increasing trend is found for Xinjiang, the eastern Tibetan Plateau, Northeast China and Southeast China. The decreasing trend of effective precipitation days for the middle- lower Yellow River valley and the increasing trend for the lower Yangtze River valley are most likely linked to anomalous monsoon circulation in East China. The most important contributor to the trend in effective precipitation depends upon the region concerned.     

Interannual Variability of Autumn Precipitation over South China and its Relation to Atmospheric Circulation and SST Anomalies

The interannual variability of autumn precipitation over South China and its relationship with atmospheric circulation and SST anomalies are examined using the autumn precipitation data of 160 stations in China and the NCEP-NCAR reanalysis dataset from 1951 to 2004. Results indicate a strong interannual variability of autumn precipitation over South China and its positive correlation with the autumn western Pacific subtropical high （WPSH）. In the flood years, the WPSH ridge line lies over the south of South China and the strengthened ridge over North Asia triggers cold air to move southward. Furthermore, there exists a significantly anomalous updraft and cyclone with the northward stream strengthened at 850 hPa and a positive anomaly center of meridional moisture transport strengthening the northward warm and humid water transport over South China. These display the reverse feature in drought years. The autumn precipitation interannual variability over South China correlates positively with SST in the western Pacific and North Pacific, whereas a negative correlation occurs in the South Indian Ocean in July. The time of the strongest lag-correlation coefficients between SST and autumn precipitation over South China is about two months, implying that the SST of the three ocean areas in July might be one of the predictors for autumn precipitation interannual variability over South China. Discussion about the linkage among July SSTs in the western Pacific, the autumn WPSH and autumn precipitation over South China suggests that SST anomalies might contribute to autumn precipitation through its close relation to the autumn WPSH.     

Warming in the northwestern Indian Ocean associated with the El Niño event

This paper investigates possible warming effects of an E1 Nifio event on the sea surface temperature anomaly （SSTA） in the northwestern Indian Ocean. Most pure positive Indian Ocean dipole （IOD） events （without an E1 Nifio event co-occurring） have a maximum positive SSTA mainly in the central Indian Ocean south of the equator, while most co-occurrences with an E1 Nifio event exhibit a northwest-southeast typical dipole mode. It is therefore inferred that warming in the northwestern Indian Ocean is closely related to the E1 Nifio event. Based on the atmospheric bridge theory, warming in the northwestern Indian Ocean during co-occurring cases may be primarily caused by relatively less latent heat loss from the ocean due to reduced wind speed. The deepened thermocline also contributes to the warming along the east coast of Africa through the suppressed upwelling of the cold water. Therefore, the E1 Nifio event is suggested to have a modulating effect on the structure of the dipole mode in the tropical Indian Ocean.     

新书架

《IAP九层大气环流模式》;《雷电防护关键技术研究》;《中国西北云水资源开发利用研究》;《干旱气象学》     

东亚大气环流由冬向夏的转变时间及其特征

利用NCEP/NCAR再分析数据集及CMAP降水资料分析了东亚大气环流由冬转夏的可能时间及其特征。结果表明,3月底4月初,东亚与西太平洋对流层纬向热力差异由东暖西冷转为东冷西暖,对流层低层大陆高压东移,使得纬向气压梯度发生逆转。与此同时,对流层低层偏南风建立,经向垂直环流也发生季节逆转。同时,3月底4月初华南已出现持续性降水雨带。所有这些特征都表明东亚大气环流可能在3月底4月初已经由冬季型开始转为夏季型。     

2011年深圳大运会海上运动气象保障探测系统

介绍了海上运动气象保障系统的设计思路和建设方案。采用合田良实的经验曲线计算出赛区波浪破碎的水深,指导沿岸自动气象站的建设;针对深圳大运会的本地特点,对海上气象、海洋要素的探测进行简化,建设临时船载探测系统和波浪浮标;分析船体对海流测量的影响因素,制定海流计布设方案;采用闪电定位和大气电场仪相结合的方式进行雷电探测。     

山东2009年10月降水气候背景及前期海温与大气环流特征

利用1951—2009年北半球500hPa高度、北太平洋海温、环流特征量、降水等资料,采用相关分析、合成分析、经验函数正交分解(EOF)、子波分析等多种统计技术,对影响山东2009年10月降水趋势的各种因素进行分析和研究。结果表明:山东10月降水大致存在3种降水分布型;在不同时间尺度的气候背景上,2009年10月山东基本处于一个少雨或由少雨向多雨转换的气候阶段;2009年春季加利福尼亚冷流的减弱,2009年6月开始的厄尔尼诺事件及6月起西太平洋副高持续的偏强、偏西、正常或偏南状态,各种指标均指示山东10月降水偏少的可能性大,预测与实况基本吻合。