【摘要】 三伏由秦汉时盛行的五行学说延伸而来,主要指中原地区气候上一年中最闷热的一段时期。利用1960～2004年我国范围内432站观测的逐日最低(Tmin)、最高气温(Tmax)和湿度值构建人体舒适度指数(THI),并分三伏区、准三伏区、潜在三伏区和非三伏区辨识了我国的气候三伏特征及其在时间上的跃变,得到华北、江淮和江南3个地区三伏入伏日期在7月4日～7月25日之间波动,多年平均的入伏时间(及伏期长度)分别为:华北7月16日(26天),江淮7月16日(29天),江南7月13日(34天);就多年平均而言,三伏强度在江淮区域最强,江南稍弱,华北最弱。各地以Tmin为指数计算的THI(Tmin)大致都呈现上升趋势,而以Tmax为指数计算的THI(Tmax)则表现出更多的年代际波动。更多还原

【Abstract】 "Three Fu" (TF) is a typical regional climate phenomenon in association with the hottest period in summer in part of China. The traditional concept of the TF has been described as an uncomfortably hottest period in summer,lasting for 30 or 40 days,without a quantified meteorological definition. In order to study this typical monthly-scale extreme climate event,the authors present a quantified definition of the TF characteristis in using the Temperature-Humidity Index (THI) based on the daily minimum/maximum temperatures (Tmin/Tmax) and the relative moisture observations during 1960-2004. Four divisions are categorized in China:TF,quasi-TF,potential-TF,and none-TF areas. The TF area covers most of southeastern China,where Asian summer monsoon prevails. To compare the TF characteristics in different climatological zones,the TF area is further divided into three subregions:the North China Plain (NC),the Yangtze-Huaihe River basins (YH),and the areas south of the Yangtze River (SY). The beginning dates of the TF are mainly between 4 and 25 July,but on average,around 16 July in NC (lasting for 26 days),16 July in YH (lasting for 29 days),and 13 July in SY (lasting for 34 days). The intensity (in terms of THI) of the TF is the strongest in YH,slightly weaker in SY,and the weakest in NC. The new TF index based on Tmin exhibits an enhancing trend during 1960-2004,but that based on Tmax is of strong interdecadal variations.更多还原