By using the 500 hPa 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 May is identified, and the climatology of SBT are analyzed with linear trend, Mann-Kendall test and wavelet analysis. The result shows that SBT appears 46.4 times per year, and the most frequent activities area is located in the south central of the Qinghai-Xizang Plateau (about 90°E92.5°E). The intensity of SBT diminished from west to east. SBT behaves most frequently in January and May, 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 Mann-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.
LIN Zhiqiang
. Objective Identify Method and Climatic Characteristics of Southern Branch Trough[J]. Plateau Meteorology, 2015
, 34(3)
: 684
-689
.
DOI: 10.7522/j.issn.1000-0534.2014.00016
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