江淮地区不同相态降水日数变化特征

Variation Characteristics of Precipitation Days with Different Phases in Yangtze-Huaihe Region

基于1960—2013年106个地面气象站观测数据,对江淮地区雨、雪、雨夹雪及冻雨4种相态降水日数气候特征、月际分布、年际变化、长期趋势以及各相态降水日数与纬度、海拔高度之间关系等方面进行探讨,结果表明:江淮地区全年降雨日数为各相态降水日数之最多,空间分布上呈南多北少的分布特点,雪日数空间分布与雨日数相反,为北多南少;雨夹雪和冻雨日数主要表现为纬向差异,东部沿海少于西部内陆;在近54a中,各相态降水日数区域平均值均呈减少趋势,其中雨、雪、雨夹雪减少趋势显著;从各站点降水日数变化趋势的空间分布看,虽然各相态降水日数普遍以减少趋势为主,但冻雨显著减少的站点最少;除降雨主要出现在3—8月,其他相态的降水出现较多的时段为11月至翌年3月;4种相态降水日数中,降雪和冻雨日数与海拔高度关系最为密切,呈显著正相关,其次为雨夹雪。

Based on the observation data of 106 ground weather stations during 1960-2013,the climate characteristics,inter-monthly distributions,inter-annual variations,and long-term trends of precipitation days with five phases such as rain,snow,sleet and freezing rain are analyzed in the Yangtze-Huaihe region.Then relationship between annual precipitation days of each phase and altitude is discussed.The results show that precipitation days over the Yangtze-Huaihe region are the most among vari-phase precipitation days,which represents a spatial distribution of more in south and less in north.Contrary to the rain days,the snow days present more in north and less in south,while the sleet days presents zonal differences that precipitation days in the eastern coastal are less than those in the western inland.In the recent 54 years,the regional averaged precipitation days of each phase showed decreasing trends,in which the phases of rain,snow and sleet are significant.Looking at the spatial distribution of variation trend for each station,although the trends of precipitation days in every phase decreased,the station numbers of freezing rain reduced significantly are the least.Rains occurred mainly in March to August,while others occurred from November to the next March.In addition,the precipitation days of snow and freezing rain are most closely related to altitude positively,and the next is sleet.