【摘要】 利用中国大陆678个台站1958-2007年的50 a逐日降水资料,分析了年、季无雨日和不同干旱程度持续性无雨日的时空特征和气候变化。结果表明:我国无雨日的空间差异很大,局地无雨日变化受大地形影响明显,无雨日高值区在南疆盆地。低值区在四川盆地,年均最大持续无雨日在南疆高于130 d,四川盆地则少于15 d。近50 a无雨日有明显地增加,平均每10 a增加4个无雨日,滇南河谷和四川盆地增加趋势最明显。各季无雨日变化亦呈增加趋势,平均每10 a增加1 d,秋季增加范围最大、趋势最为明显。无雨日持续的天数越长,在全国分布的范围就越小。对中国大陆气候区划分析表明,8个气候区持续性无雨日主要呈增加趋势,华中、华北、东北和康滇增加的程度较大,而西北的持续无雨日呈明显减少的趋势。更多还原

【Abstract】 In the recent years,with the global warming,the number of extreme drought events is increasing.During the period of the previous study,we just focused on drought climate changes caused by the decline of precipitation.However,the impact of drought events on agriculture is determined not only by precipitation but also by the number of persistent rainless days.The rainless days are a significant index indicating drought and it is necessary to do some research about it.However,we find few researches on the rainless days,fewer scholars engaged in the research on rainless days of the entire China.As a result,it is tremendously significant to do some researches about the rainless days and continuing rainless days for agriculture and the prevention and prediction of drought disaster.This paper shows the long term climate variation characteristics of China’s mainland by comparing the temporal and spatial characteristics of rainless days and persistent rainless days over the past 50 years.By analyzing the daily precipitation data of 678 stations in China’s mainland during the period of 1958-2007 with tendency coefficient method and climate tendency method,we got the mean spatial distribution and temporal trends of the rainless days in seasonal and annual scales.Then we analyzed the directional distribution characteristics of the annual maximum persistent rainless days and various persistent rainless days which can reflect difference in degree of drought.At the end of the main body,the secular trend of persistent rainless days of eight climatic regions in China’s mainland is represented.The results show that there is a remarkable spatial difference in the distribution of rainless days,and the terrain is the significant factor that effects the local rainless days variation.The number of multi-year average rainless days is up to 249 d.We can find that the maximum rainless days is in southern Xinjiang basin and the minimum rainless days is in Sichuan province.During summer,the region with minimum rainless days is southeastern Qinghai-Xizang Plateau,which is probably due to the influence of southwest monsoon.The maximum of mean annual persistent rainless days is more than 130 d in southern Xinjiang and less than 15 d in Sichuan basin.With the number of persistent rainless days increasing,the area of persistent rainless days distribution decreased gradually in the northwest direction.Except for the southern Xinjiang,the number of persistent rainless days is less than 75 d.The number of rainless days significantly increased with a mean rate of 4 d /10 a during the last 50 years.A significant increasing is revealed in southern Yunnan province and Sichuan basin.The number of seasonal rainless days increased with a mean rate of 1 d /10 a,and autumn is the most remarkable season.The number of persistent rainless days is increasing in eight climate regions,and four remarkable regions are northern China,northeastern China,southwestern China and central China.But it is opposite in the northwestern China,which is in accordance with the fact that the northwestern China is turning to a warm-humid style from a warm-dry style.更多还原