全球夏、冬季加热场的气候学特征及其年代际变化

Climatic Characteristics and Interdecadal Changes of Global Summer and Winter Heat Sources

利用NCEP/NCAR再分析资料,计算了1948—2002年全球夏、冬季节大气热源的气候分布,并对其年代际变化规律进行分析。研究表明,全球存在4个主要的大气热源中心,其位置随季节的改变而改变。夏季分别位于中非、孟加拉湾附近、热带西太平洋菲律宾群岛附近及加勒比海西南部;冬季则移至南非、海洋大陆至印度洋一带、澳大利亚西北部至南太平洋一带及南美洲北部。夏季中非、热带西太平洋菲律宾群岛附近及加勒比海西南部大气热源都表现出明显的年代际变化特征,中非热源在20世纪70年代存在减弱突变,而热带西太平洋菲律宾群岛和加勒比海西南部热源存在增强突变,孟加拉湾热源强度存在减弱变化趋势。冬季南美洲北部热源具有明显的年代际变化,在70年代中期存在增强突变,南非和海洋大陆至印度洋一带热源强度存在增强变化趋势,而澳大利亚西北至南太平洋一带热源强度存在减弱变化趋势。

Based on the NCEP/NCAR reanalysis data during 1948-2002, the climatic distributions of summer and winter atmospheric heat sources are computed and their interdecadal variabilities analysed. Results show that there were four major atmospheric heat source centers and their positions changed seasonally. In summer, they located in central Africa, the Bay of Bengal, the Philippines/tropical western Pacific and the southwest Caribbean Sea, while in winter, they moved to South Africa, the Oceanic-Continent to the tropical Indian Ocean, northwest Australia to the tropical South Pacific and northern South America, respectively. The intensities of summer heat sources in the four major center areas all showed obvious interdecadal variations with an abrupt weakening in central Africa in 1972, an abrupt strengthening in the Philippines/tropical western Pacific in 1972 and in the southwest Caribbean Sea in 1975, and a generally weakening trend in the Bay of Bengal. In winter, the intensities of heat sources in the four center areas also showed obvious interdecadal variations with an abrupt strengthening only in northern South America, and a generally strengthening/weakening trend in South Africa and the Oceanic Continent to the tropical Indian Ocean/northwest Australia to the tropical South Pacific.