南支槽的客观识别方法及其气候特征

Objective Identify Method and Climatic Characteristics of Southern Branch Trough

基于槽的客观识别方法,提出南支槽强度定义,利用NCEP/NCAR再分析资料500 h Pa高度场识别了1953 2012年冬半年逐日南支槽分布,利用线性趋势、Mann-Kendall突变检测和小波分析等分析了近60年南支槽的气候及其变化特征。结果表明:南支槽年平均活动频次为46.4次,活动最频繁区位于青藏高原中部南侧(90°E 92.5°E),强度自西向东减弱;1月和5月的活动频次最高,1月和2月的强度最大;近60年南支槽活动频次有增加趋势,每年平均增加0.12次,在1960年前后发生突变,之前年平均为39.8次,之后年平均为47.5次;最显著周期为7年。对南支槽不同位置的整层水汽输送通量合成分析表明,南支槽前为水汽输送异常大值区,该水汽输送大值区随南支槽东移而东移。

By using the 500 h Pa geopotential height of NCEP / NCAR reanalysis data from 1953 to 2012,based on the objective identify method of trough axis,the trough axis intensity index is described. The daily southern branch trough( SBT) in the period from October to the following M ay is identified,and the climatology of SBT are analyzed with linear trend,M ann- Kendall test and wavelet analysis. The result shows that SBT appears46. 4 times per year,and the most frequent activities area is located in the south central of the Qinghai-Xizang Plateau( about 90°E 92. 5° E). The intensity of SBT diminished from west to east. SBT behaves most frequently in January and M ay,and behaves most strongly in January and February. The frequency of the SBT has an insignificant increasing trend for about increasing 0. 12 times per year in recent 60 years. The M ann- Kendall test shows an abrupt change occurred in 1960,the annual average 39. 8 times before,and 47. 5 times the average annual after. The most significant period of SBT is 7-year cycle. Different positions on the SBT of whole levels water vapor transport flux synthesis analysis showed that the water vapor transport large area locates eastside of the SBT and moves eastward with the SBT.