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| Identifying Global Monsoon Troughs and Global Atmospheric Centers of Action on a Pentad Scale |
| QIAN Wei-Hong,TANG Shuai-Qi |
| Department of Atmospheric Science, Peking University, Beijing 100871,Department of Atmospheric Science, Peking University, Beijing 100871 |
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Abstract Using two datasets of global pentad grid precipitation and global 850 hPa geopotential height during 1979-2007, this study identified global monsoon troughs and global atmospheric centers of action (ACAs) on a pentad scale. The global monsoon troughs consist of planetary-scale monsoon troughs and peninsula-scale monsoon troughs. Forced by seasonal variations in solar radiation, the inter-tropical convergence zones (ITCZs) represent the planetary-scale monsoon troughs, which are active and shift over the tropical North Pacific, the tropical North Atlantic, and the tropical South Indian oceans. The peninsula-scale monsoon troughs are originated from regional land-sea topography and varied with contrasts in seasonal land-sea surface temperatures and precipitation. During the boreal summer, five peninsula-scale troughs and one planetary-scale trough are distributed in the Asia-Northwest Pacific (NWP) region. In total, 22 troughs, nine monsoon troughs, and 19 ACAs in the lower troposphere were identified. Relevant ACAs may be useful in constructing regional monsoon and circulation indices.
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Received: 30 October 2009
Revised: 11 December 2009
Accepted: 20 December 2009
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