华北地区1972年和1997年干旱特征及其影响系统分析

利用华北地区实测的月降水量资料,美国NCAR/NCEP 850 hPa的矢量风5、00 hPa和850 hPa的位势高度等再分析资料,分析了华北地区1972年和1997年这2个干旱年干旱的空间分布、强度分布和持续时间,以及西太平洋副热带高压变化、季风进退和欧亚大气环流异常情况.结果表明:1972年是季风正常年,但该年亚洲大陆高压偏强且持续存在、西太平洋副热带高压持续偏弱,导致了干旱的发生与持续;而1997年由于持续偏强的亚洲大陆高压、持续偏弱的季风和西太平洋副热带高压造成该地区严重干旱.

Drought characteristics and its affecting system in North China in 1972 and 1997

The spatial distribution and intensity distribution of drought in North China and its duration in 1972 and 1997 were investigated based on the NCAR/NCEP reanalysis data,including vector wind at 850 hPa and geopotential height at 500 hPa and 850 hPa,and observed monthly precipitation data by 104 gauges.The causes of drought in this region were discussed according to the variations of western Pacific subtropical high,the summer monsoon,and the general circulation of atmosphere in Euro-Asian region in the two years.The result showed that,in 1972,a normal year of summer monsoon,the relative strong and continuous Asian continent high pressure system and weak western Pacific subtropical high led to the continuous drought in this region,while in 1997,the relative strong and continuous Asian continent high pressure system and relative weak summer monsoon and western Pacific subtropical high led to serious drought in this region.