Climatological characteristics of summer drought and its causes in Shaanxi Province |
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DOI:10.7606/j.issn.1000-7601.2009.02.06 |
Key Words: summer drought climatological characteristics atmospherical circulation |
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Abstract: |
Using the reanalyzed data of NCAR/NCEP and observation data from 15 stations in Shaanxi Province in summertime of June July and August during the time from1961to2006 climatological characteristics of summer droughts and their representative circulations are analyzed.The results show that high temperature little precipitation and obvious decadical variations are the main features of summer drought in Shaanxi. Furthermore most of summer droughts occur in the decades of1960 1970and1990.The atmospherical circulation of serious summer droughts of Shaanxi can be described as the followings.The weaker western Pacific subtropical high the stronger northeast-moving Tibetan high as well as the Tibetan high or the high belt based on the Tibetan high gets united with the long-wave ridge or the western Pacific subtropical high are the typical circulations of Shaanxi summer droughts.Additionally the consist position of southern Asian high at the level of 100hPa the high at the 300 and the Tibetan high at500hPa and its correspondence with the warm center in the whole troposphere are the typical circulations of the persistent and abnormal summer droughts. |