中国南海低云量季节和年际变化时空特征分析
Spatiotemporal Characteristics of Seasonal and Interannual Variations of Low Cloud Amount over the South China Sea
中文摘要：
利用国际卫星云气候计划（ISCCP）提供的D2云气候资料集、NCEP再分析资料、Nino3.4海温资料等分析探讨中国南海（简称南海）低云量的年平均、季节循环、年际变化的时空分布特征及可能原因。结果表明：低云量年平均气候态呈东北—西南的带状分布，大值区具有沿海陆交界处海岸线分布的特征；从时间序列来看，2001年以前的低云量指数波动幅度较大，2001—2007年波动幅度变小；南海低云量分布存在显著的季节差异，这与南海夏、冬季风的爆发有关，低云量夏季（6—8月）的年际变化最小，冬季（12月—次年2月）的年际变化最大；低云量季节变化存在2～5 a的振荡周期，与ENSO循环周期相似，二者存在一定的联系；秋季低云量的年际变化与厄尔尼诺现象密切相关，当厄尔尼诺发生时南海低云量增多。
中文关键词：
中国南海，低云量，标准差，小波分析，气候变化
KeyWords：
South China Sea, low cloud amount, standard deviation, wavelet analysis, climate change
Abstract：
By using the D2 cloud climate datasets from the International Satellite Cloud Climatology Project (ISCCP), NCEP reanalysis data and Nino3.4 SST data, we analyzed the spatiotemporal distribution characteristics and possible reasons of the annual average of the low cloud amount over the South China Sea (SCS), its seasonal circulation as well as its interannual variation. The results show that the annual average climatological state of low cloud amount exerts a northeast to southwest beltlike distribution. In particular, the high value area is located along the coastline of the land-sea boundary. From the perspective of time series, prior to 2001, the fluctuation range of low cloud amount index over the SCS was relatively large, while it went the opposite from 2001 to 2007. The distribution of low cloud amount over the SCS has remarkable seasonal feature, which is related to the onset of summer monsoon and winter monsoon over the SCS. The interannual variation of low cloud amount over the SCS is minimal in summer (June to August) and peaks in winter (December to February). On the interannual time scale, the oscillation period of seasonal variation of low cloud amount over the SCS is 2 to 5 years, which coincides with the period of the ENSO cycle. This finding evidences the correlation between the two. In autumn, the interannual variation of low cloud amount over the SCS is closely related to the El Ni?o phenomenon. The occurrence of El Ni?o is accompanied with increased low cloud amount over the SCS.