全球各主要季风区湿季和干季降雨变化趋势、变率和偏度特征的对比

Comparison of Rainfall Trends,Variability and Skewness Characteristics in Wet and Dry Seasons in Major Global Monsoon Regions

对比了1979—2020年全球8个主要季风区湿季和干季降雨的长期变化趋势、变率和偏度特征。主要结果如下:(1)在长期变化趋势方面,东亚、西北太平洋和北非季风的湿季降雨以及印度季风的干季降雨呈现显著的增加趋势,而北美和南美季风的干季降雨和南美季风的湿季降雨呈现显著的下降趋势。东亚和北非季风(南美季风)的湿季—干季降雨差值呈现显著的增加(下降)趋势。(2)在变率方面,北美和北非季风湿季和干季降雨的方差在2000—2020年(P2时期)要小于1979—1999年(P1时期);南非和澳洲季风湿季和干季降雨的方差在P2时期要大于P1时期;东亚、西北太平洋和南美季风降雨方差的变化在湿季和干季存在不一致性,湿季(干季)降雨的方差在P2时期增加(减小)。(3)在偏度方面,东亚、印度、澳洲和南非季风干季降雨和东亚季风湿季降雨的偏度值在P2时期增加;而西北太平洋季风干季降雨和北非季风湿季降雨的偏度值在P2时期减小。

In this study,the long-term trends,variability and skewness characteristics for rainfall in wet and dry seasons in eight global major monsoon regions from 1979 to 2020 were compared.The main results were as follows:(1)The wet-season precipitation of the East Asian,Northwest Pacific and North African monsoons and the dry-season precipitation of the Indian monsoon showed a significant increasing trend,while the dry-season precipitation of the North American and South American monsoons and wet-season precipitation of the South American monsoon displayed a significant downward trend.The rainfall difference between the wet season and the dry season showed a significant increasing(decreasing)trend for the East Asian and North African monsoons(the South American monsoon).(2)The rainfall variances in the wet and dry seasons in 2000—2020(P2 period)were smaller than those in 1979—1999(P1 period)for the North American and North African monsoons.The rainfall variances in the wet and dry seasons in P2 period were larger for the South African and Australian monsoons.The rainfall variances of the East Asian,Northwest Pacific and South American monsoons were inconsistent between the wet season and the dry season,which were increased(decreased)for the wet-season(dry-season)rainfall during P2 period.(3)The rainfall skewness was increased in P2 period for the dry-season precipitation in East Asian,Indian,Australian and South African monsoons and the wet-season precipitation in the East Asian monsoon,but decreased for the dry-season precipitation in the Northwest Pacific monsoon and the wet-season precipitation in the North African monsoon.