对1948—2014年67年的江淮地区5-7月气温序列,利用EOF、功率谱和非线性映射法进行气候阶段客观划分,可分为3个时长近似的气候阶段:气温趋势下降阶段(1948—1970年)、气温趋势上升阶段(1971—1994年)和气温趋势缓升阶段(1995—2014年),它们的气候特征可用特定气温指数定量表达。其次,对各阶段江淮气旋统计特征与各阶段气温变化趋势进行对比,结果显示,气旋年平均发生频数,生命期大于48 h的气旋,各类气旋数量(深厚型,浅薄型和底层型),以及气旋路径(纬向型,经向型和打转型)的特征演变,均有明显响应阶段性气温变化的表现,阶段气温的趋冷抑制江淮气旋的活动,而阶段气温的增暖促进了气旋的发展、维持与活跃,并引导气旋位置的北进。对气旋结构特征的合成分析显示,在气旋结构中的气旋中心强度、温度梯度、气旋急流最大风速,气旋水汽通量通道的强度、长度、位置以及表征气旋斜压性的气旋冷暖气团的强度、厚度和北进南退位置等特征的演变,均与阶段内环境气温的趋冷、增暖、缓升相对应。这些结果清晰显示在环境气温下降趋冷阶段,气温变化减弱了气旋的结构强度,抑制了气旋的活跃性,在环境气温增温和缓升阶段,气温变化加强了气旋结构的稳定成长与增强,并维持了气旋的活跃性。
By EOF, Power spectrum and nonlinear mapping methods, the temperature time series of May to July in Jianghuai river basins from 1948-2014 (67 years) were objectively divided into several climate stages. The time series were divided into three climate stages with similar lengths: the stage with its air temperature trend going downwards stage (1948-1970) ; the stage with its air temperature trend going upwards (1971-1994) and the stage with its air temperature trend going gentle upwards (1995-2014). Their climate characteristics can be quantified by a special climate index. Then, the statistic characteristics of Jianghuai cyclones in the three climate stages were compared with the cooling or warming trends. The results showed that characteristic evolutions of the frequency of yearly average of Jianhuai cyclones, the cyclones with their life cycles in the area longer than 48h, the cyclones with three types of thickness, shallow and bottom shapes classified according to the cyclone height, the cyclones with three kinds of zonal, meridional, and circular trajectory, responded to the temperature changing trends in the three climate stages. The cooling trends of the stage temperature restrained the activity of Jianghuai cyclones, and the warming trends of the stage temperature promoted the cyclone' s development, maintaining, activity, and also led cyclone moving towards to north further. The composite analysis of cyclone structures showed that the evolution characteristics in the center intensity, temperature grads, the maxima velocity of jet of the cyclones, and the inten- sity, length and position of the vapor flux passage of the Jianghuai cyclones, also the intensity, thickness, the positions of the warm and cold air masses within the cyclones, all responded to the trend change of stage temperature including cooling, warming and gentle warming. The results show clearly that temperature cooling reduces the intensity of cyclone structures and restrains the activity of cyclones in the temperatures t