摘要
文中根据 NCEP/NCAR再分析资料 ,分析了北太平洋副热带高压系统的变化。 5～ 9月由于亚洲夏季风的建立及活动 ,北半球副热带高压系统在 6 0～ 1 2 0°E出现断裂 ,夏季西太平洋副热带高压脊点平均伸展到 1 2 0°E,其年际变化反映了亚洲夏季风的强弱。强夏季风年 5 0 0h Pa西太平洋副热带高压脊线位于 3 0°N以北 ,并分裂成两个中心 ,印度低压强 ;弱夏季风年西太平洋副热带高压脊线位于 3 0°N以南 ,表现为北太平洋高压中心向西伸展的高压脊 ,印度低压弱。夏季西太平洋副热带高压的季内活动有两种模态 :第 1种表现为副热带高压系统以 2 0～ 3 0 d的周期从北太平洋中部的副热带高压中心一次次地向西扩张到 1 2 0°E以西 ,这类过程大多出现在亚洲夏季风强度偏弱年 ;第 2种模态表现为副热带高压系统以 2 0～ 3 0 d的周期一次次地由东向西扩充时 ,在 1 2 5～ 1 5 5°E停滞 ,这类过程大多出现在亚洲夏季风强度偏强年。江淮流域梅雨的中断和结束与北太平洋副热带高压系统 2 0～ 3 0 d季内振荡有关。西太平洋副热带高压 5～ 1 0 d的短期活动受 3 5～ 45°N西风带活动的影响 ,当西风槽在中国沿海和西太平洋地区向南伸展到 3 0°N以南后 。
The behavior of the subtropical high (SH) over the West Pacific in summer manifests marked inter-annual,seasonal,intra-seasonal and short period (5-10 days) variations. In strong summer monsoon years the ridge of SH extends further northward than in weak monsoon years, and there are two separate anticyclone centers, one is over the West Pacific and the other over the Middle Pacific. In the weak monsoon years the behavior of SH mainly manifests a ridge extending westward from the Middle Pacific. For seasonal variations the ridge of SH is situated to the south of 20°N before June, extends to 25°N when the Meiyu season in the Yangtze River Valley begins, and extends further northward to the north of 30°N in mid July , when the Meiyu season ceases in September the ridge of SH retreats rapidly southward. For intra-seasonal variations there are two modes, The first mode is the extension of the ridge of SH westward from the Middle Pacific with a period of 20-30 days. The second mode is that the ridge of SH extends westward from the Middle Pacific, intensifies to form a separate high pressure center, and stagnates in the West Pacific. The extension or retreat of the ridge of SH has a close relation to the break or cease of the Meiyu in China. For short period (5-10 days) variations, when a trough in the westerly in the middle latitudes moves eastward, intensifies rapidly to the east of Japan Islands, and extends southward into the subtropical, the ridge of SH to the west of the digging trough intensifies and extends into the China mainland.
出处
《气象学报》
CSCD
北大核心
2001年第6期747-758,共12页
Acta Meteorologica Sinica
基金
"国家重点基础研究发展规划"( G1 9980 4 0 90 0 )
国家自然科学基金委员会重点课题项目"副热带高压带的变异机理"( 4 96 31 70 )。
关键词
夏季
太平洋
副热带高压
年际变化
月变化
大气环流
Subtropical high,West Pacific,Inter-annual variations,Short period (5-10 days) variations.
