摘要
通过诊断分析研究了北半球中高纬大气低频振荡随纬度的变化特征,利用1950—2005年北半球20～75°N逐日500hPa位势高度场资料分析了功率谱。结果表明,(1)大气低频周期随纬度变化,夏季低频周期在45°N有最大值,为52.6d,在低纬和高纬低频周期较小;冬季低频周期最大值位于35°N,为49.9d,最小值位于60°N。(2)无论ElNino年还是LaNina年,低频周期随纬度变化幅度在夏季都较正常年剧烈,最大振幅达到30d,而对冬季影响不大。原本位于35°N的最长低频周期在LaNina年移至65°N。(3)ElNino年和LaNina年,低频周期随纬度平均值在冬、夏季差异不大;而在正常年份和所有年份,低频周期随纬度平均值在冬、夏季差异明显。(4)就北半球平均而言,无论ElNino年、LaNina年、正常年还是所有年,夏季低频周期都要小于冬季;ElNino(LaNina)事件在冬、夏季都有使大气低频周期缩短(延长)的趋势。
A diagnostic analysis is carded out to investigate the intra-seasonal oscillations （ISO） in extra-tropical latitudes. The power spectrum analysis is performed for the daily northern 500 hPa geopotential height field data in the mid-high latitudes（20-75°N） from 1950 to 2005. The conclusion is received that ： （ 1 ） the cycle of ISO varies with latitudes. In summer, the longest cycle of ISO locates at 45~N,with a period of 52.6 d. However, the cycle of ISO tends to be small in relatively lower and higher latitudes. In winter, the longest cycle of ISO appears around 35°N, with a period of 49.9 d, while the shortest cycle of ISO lies around 60°N. During La Nina years, the location of longest cycle shifts from 35°N to 65°N. （2）The period of ISO varies with latitudes more greatly during ENSO-years, especially in summer. （3） The difference of the ISO period between summer and winter during ENSOyears is tiny,but is great during normal-years and for all-years. （4）Main periods of ISO show a shortening/lengthening tendency during El Nino/La Nina event.
出处
《大气科学学报》
CSCD
北大核心
2009年第4期582-589,共8页
Transactions of Atmospheric Sciences
基金
国家教育部"高等学校博士学科点专项科研基金"
