摘要:
该文针对全球温度场在20世纪80年代全球明显的突然变暖事件,研究了变暖前后全球温度场和降水场的时空分布特征,以及相应季风环流圈的变化特征,并且与20世纪60年代全球变冷气候事件作了对比分析.结果表明,变暖后全球大范围增温,增温地区包括欧亚大陆大部、非洲地区大部和印度洋南部.与此同时,全球降水场也有明显的变化.1990—1995年与1980—1985年相比较,中国华北地区大部分地区、印度中南部和北非Sahel大部分地区夏季总降水量有所回升,而中国华北地区南部地区和印度北部地区降水有所减少.对比分析80年代变暖前后气候环流场,发现非洲夏季风在变暖后有所加强,印度夏季风有所减弱,东亚夏季风强度微弱加强.从海陆热力对比和华北和北非Sahel等地的夏季降水量的小波分析来看,60年代变冷气候事件以年代际信号为主,同位相叠加突出了年代际振荡的作用和强度;而80年代夏季降水量的各时间尺度年代际信号符号相反,相互抵消;与此同时,80年代年际时间尺度的信号较强,起主导作用.所以,80年代气候变暖事件与60年代气候变冷事件相比较,并不是单纯的气候年代际反位相振荡的结果,而是不同时间尺度信号相互作用下引起的气候不同的响应.
Abstract:
For the global warming event sharpened in 1980s,this paper studied the differences of temperature and precipitation fields respectively between 1990-1995 and 1980-1985.Furthermore,this global warming event was compared with global cooling event in 1960s.The results showed that after mid-1980s,the global warming sharpened and the warmed areas included most of European-Asian continent except for the Tibetan Plateau,most of African continent and the south of Indian Ocean.Synchronously,the global precipitation had changed obviously too.Compared with the increase of summer rainfall over North of Africa during 1980-1985 and 1990-1995,that of northern area of North China increased while south area of it decreased,and the rainfall of north India decreased remarkably but that of the middle and south of India increased.In north of China and Sahel,it was showed that the rainfall during 1990-1995 increased,but was far smaller to reach that before mid-1960s.The differences of monsoon cells between 1990-1995 and 1980-1985 indicated that the African summer monsoon reinforced after global warming,but the Indian summer monsoon weakened evidently and the East Asian summer monsoon enhanced somewhat.On the basis of wavelet analyses of land-sea thermal contrast between Indian Ocean and Asian-African continent,summer precipitation over north of China and Sahel in African respectively,it was concluded that in 1960s,there were different in-phase interdecadal time-scale signals and they interacted to get reinforcement,thus the interdecadal oscillations played key role during this period;contrastively,in 1980s,there existed different decadal and interdecadal time-sclae signals which appeared opposite signs,so they counteracted with each other to become weak.Meanwhile it should be noted that the interannual signals reinforced remarkably in 1980s,so they became the most important signals and played key role in this event.Therefore,compared with climate event in 1960s,global warming in 1980s was not a simple out-of-phase interdecadal climate change event,but the different climate responses to different physical factors.
百度学术
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