南极气候变化的季节特征

SEASONAL FEATURES OF ANTARCTIC CLIMATIC CHANGE

利用１９６２～１９９３年南极１６站地面至３０ｈＰａ１０个标准层上月平均温度、南极臭氧总量以及２８００ＭＨｚ太阳通量资料，采用最大熵功率谱方法，研究了各季中月南极诸高度气候的线性趋势变化、熵谱特征及其可能原因。结果显示：南极平流层气温（臭氧总量）在各月均呈变冷（减少）趋势，１０月１００ｈＰａ气温（臭氧总量）１０年的变率最大达－１．８℃（－１４．８％）。南极对流层气温（２８００ＭＨｚ太阳通量）在各月均呈显著增暖（增强）趋势，１月５００ｈＰａ气温（太阳通量）１０年的变率高达０．４℃（２２．１个单位）。各月太阳通量均呈显著的３年及９～１０年甚低频—年代际周期变化。而对流层８５０～５００ｈＰａ气温变化熵谱仅在７月具有相应的特征，南极对流层顶气温在各季中月均无显著的趋势变化及周期性变化。提出南极春季臭氧的显著减少及夏季太阳通量的增强是平流层显著变冷及对流层变暖的重要原因；南极夏季对流层显著增暖导致南极大陆边缘部分冰雪消融，可能是近年来全球海平面升高的重要原因之一。

Used in this study are monthly mean temperatures at 10 standard levels from surface to 30 hPa, total ozone and 2 800 MHz solar flux over Antarctic 16 stations in 1962～1993 that are treated by a maximum entropy spectrum method with the aim to uncover the linear trend variation in climate and spectral features at all the levels alongside possible causes discussed for January, April, July and October (as mid season months). Evidence shows that stratospheric temperature (total ozone) is becoming lower (smaller) for these months; 100 hPa temperature (total ozone) shows maximum variability in October of -1.8℃ (-14.8%) per 10 years; tropospheric temperature (2 800 MHz solar flux) has a tendency to warm up (enhance) in these months; 500 hPa temperature (solar flux) has the variability of 0.4℃ (22.1 × 2 800 MHz) per decade in January with the flux displaying salient periods of 3 and 9～10 years for these months; tropospheric 850～500 hPa temperature variation entropy spectrum exhibits corresponding features only in July; no appreciable trend and periods occur to tropopause temperature in the study months; pronounced decrease of ozone in spring and growth of solar flux in summer represent major causes of stratospheric cooling and tropospheric warming; Antarctic ice melting related to the summer tropospheric warming may be a major cause of sea level rise on a global basis.