摘要
利用陕西省自1961年以来的夏季降水资料和对应的NCEP逐日再分析资料,对伏旱出现的时段、强度、典型夏涝年和伏旱年的合成环流特征等进行分析,力图寻找陕西省伏旱天气的主要影响因子。结果表明:陕西省夏季降水量存在着明显周期,其中关中地区为2a和5～6a;陕南地区为3a左右和10a周期;欧亚大陆上空槽、脊不明显或有弱脊存在时,无冷空气南下或水汽条件不充分,均易形成伏旱天气;伏旱年份的当年春季降水量可能显著偏多;太阳黑子相对数与陕西省伏旱天气具有一定的对应关系。
In terms of precipitation data of summer and corresponding NCEP/NCAR daily reanalysis data since 1961 in Shanxi province, period and intensity of drought and synthesis circulation features of typical wet and drought summers were analyzed to find out the main impact factor of summer drought. It is found that, summer precipitation of Shanxi province has obvious cycling characteristics, the most obvious precipitation of Guanzhong area are 2 a and 5 - 6 a; there are 3 a and 10 a in Shannan; because of insufficiency of vapour conditions, summer drought is formed easily when no trough and ridge is less evident over the continent of Europeand Asia; precipitation of autumn during summmer drought years is more than normal markedly, sunspot relative number is related to summer drought in Shanxi province.
关键词
伏旱
降水强度指数
合成环流特征
summer drought
the index of precipitation intensity
synthesis circulation features
