首页|Two Modes and Their Seasonal and Interannual Variation of the Baroclinic Waves/Storm Tracks over the Wintertime North Pacific

Two Modes and Their Seasonal and Interannual Variation of the Baroclinic Waves/Storm Tracks over the Wintertime North Pacific

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In this study, a newly developed method, termed moving empirical orthogonal function analysis (MEOF), is applied to the study of midlatitude baroclinic waves over the wintertime North Pacific from 1979 to 2009.It is shown that when the daily, high-pass filtered (2-10 days) meridional wind at 250 hPa is chosen as the variable of the MEOF analysis, typical features of baroclinic waves/storm tracks over the wintertime North Pacific can be well described by this method.It is found that the first two leading modes of the MEOF analysis, MEOF 1 and MEOF2, assume quite different patterns.MEOF1 takes the form of a single wave train running in the east-west direction along 40°N, while MEOF2 is a double wave train pattern running in the east-west direction along 50°N and 30°N, respectively.The shift composites of various anomalous fields based on MEOF1 and MEOF2 assume typical baroclinic wave features.MEOF1 represents a primary storm track pulsing with an intrinsic time scale of two days.It shows significant "midwinter suppression" and apparent interannual variability.It is stronger after the mid-1990s than before the mid-1990s.MEOF2 represents a double-branch storm track, also with an intrinsic time scale of approximately two days, running along 50°N and 30°N, respectively.It shows no apparent seasonal variation, but its interannual and decadal variation is quite clear.It oscillates with larger amplitude and longer periods after the mid-1990s than before the mid-1990s, and is heavily modulated by E1 Ni(n)o-Southern Oscillation (ENSO).

baroclinic wavesPacific storm tracksMEOF analysisENSO

JIANG Yuxin、TAN Benkui

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Department of Atmospheric and Oceanic Sciences,Peking University,Beijing 100871

This research was supported by the National Natural Science Foundation of ChinaThis research was supported by the National Natural Science Foundation of China

4137506041130962

2015

10.1007/s00376-015-4251-3

大气科学进展(英文版)
中国科学院大气物理研究所

大气科学进展(英文版)

CSTPCDCSCDSCI
影响因子：0.741
ISSN：0256-1530
年,卷(期)：2015.32(9)
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