1962-2011年长江流域极端气温事件分析

Extreme temperature events in Yangtze River Basin during 1962-2011

根据1962-2011年长江流域115个气象站点的逐日最高气温、日最低气温资料,利用线性倾向估计法、主成分分析及相关分析法,并根据选取的16个极端气温指标,分析了该地区极端气温的时间变化趋势和空间分布规律。结果表明:(1)冷昼日数、冷夜日数、冰冻日数、霜冻日数、冷持续日数分别以-0.84、-2.78、-0.48、-3.29、-0.67d.(10a)-1的趋势减小,而暖昼日数、暖夜日数、夏季日数、热夜日数、暖持续日数、生物生长季以2.24、2.86、2.93、1.80、0.83、2.30d.(10a)-1的趋势增加,日最高(低)气温的极低值、日最高(低)气温的极高值和极端气温日较差的倾向率分别为0.33、0.47、0.16、0.19、-0.07oC.(10a)-1;(2)冷指数(冷夜日数、日最高气温的极低值、日最低气温的极低值)的变暖幅度明显大于暖指数(暖夜日数、日最高气温的极高值、日最低气温的极高值),夜指数(暖夜日数、冷夜日数)的变暖幅度明显大于昼指数(暖昼日数、冷昼日数);(3)空间分布上,长江上游区域冷指数的平均值大于其中下游区域,而暖指数和生物生长季则是中下游多年平均值大于上游区域(暖持续日数除外);(4)因子分析的结果表明,除了极端气温日较差之外,各极端气温指数之间均呈现很好的相关性。

Based on daily maximum and minimum temperature observed by the China Meteorological Administration at 115 meteorological stations in the Yangtze River Basin from 1962 to 2011, the methods of linear regression, factor analysis and correlation analysis are employed to analyze the temporal variability and spatial distribution of climate extremes. Sixteen indices of extreme temperature are studied. The results are as follows： （1） The occurrence of cold days, cold nights, ice days, frost days and cold spell duration days has significantly decreased by -0.84, -2.78, -0.48, -3.29 and -0.67 days/decade, respectively, while the occurrence of warm days, warm nights, summer days, tropical nights, warm spell duration days and growing season length shows statistically significant increasing trends at rates of 2.24, 2.86, 2.93, 1.80, 0.83 and 2.30 days/decade, respectively. The tendency rate of monthly minimum value of daily maximum （minimum） temperature, monthly maximum value of daily maximum （minimum） and diurnal temperature range is 0.33, 0.47, 0.16, 0.19 and-0.07 ~C/ decade, respectively. （2） The magnitudes of changes in cold indices （cold nights, monthly minimum value of daily maximum, monthly minimum value of daily minimum） are obviously greater than those of warm indices （warm nights, monthly maximum value of daily maximum and monthly maximum value of daily minimum）. The change ranges of night indices （warm nights and cold nights） are larger than those of day indices （warm days and cold days）, indicating that the changes of day. and night temperature are asymmetrical. （3） Spatially, the regionally averaged values of cold indices in the upper reaches of the Yangtze River Basin are larger than in the middle and lower reaches. However, the regionally averaged values of warm indices and growing seasons except warm spell duration indicator are larger in the middle and lower reaches than in the upper reaches. （4） The extreme temperature indice are highly correlated with each other except diurnal temperature range.