Characteristics of the Summertime Boundary Layer and Atmospheric Vertical Structure over the Sichuan Basin
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- JIANG Xingwen
- Institute of Plateau Meteorology, China Meteorological Administration
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- LI Yueqing
- Institute of Plateau Meteorology, China Meteorological Administration
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- ZHAO Xingbing
- Institute of Plateau Meteorology, China Meteorological Administration
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- KOIKE Toshio
- Department of Civil Engineering, University of Tokyo
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The Sichuan Basin (SCB), located east of the Tibetan Plateau, is surrounded by mountains. This study examines the influence of terrain and weather events on the diurnal cycle of the planetary boundary layer (PBL) and the vertical structure of the atmosphere over the SCB, by utilizing field data obtained mainly from Wenjiang Station (western SCB) for the period 20 June-19 July 2008. The results show inversion layers of specific humidity and prevailing wind directions in the lower troposphere from the southwest and northeast. Migration of the 500 hPa trough to the western SCB results in the formation of low-level jets and cyclonic circulation, induced by terrain obstruction of northward airflow entering the basin from its southeast corner. Migration of the 500 hPa trough to the west (east) of Wenjiang Station results in an abruptly decreased (increased) surface downward short-wave radiation flux, which is associated with an increased (decreased) cloud fraction. In turn, this results in decreased (increased) upward sensible and latent heat fluxes, and a decrease (increase) in the elevation of the mixing layer (ML). Rapid increase in the ML height depends not only on the intensity of nocturnal temperature inversions, but also on the stability of the lower troposphere. At Wenjiang Station, the period prior to rainfall events is marked by increasing water vapor, instability and wind speed, and the wind direction changes from westerly to easterly. Subsequent to rainfall events, the PBL is rapidly restored to its normal state. The PBL is an important source of water vapor for rainfall. An increase in water vapor in the lower troposphere during night-time contributes to nocturnal rainfall. Basin terrain may play an important role in the formation of the southwest China vortex.
収録刊行物
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- 気象集誌. 第2輯
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気象集誌. 第2輯 90C (0), 33-54, 2012
公益社団法人 日本気象学会
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詳細情報 詳細情報について
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- CRID
- 1390282681480091904
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- NII論文ID
- 130004435213
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- NII書誌ID
- AA00702524
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- ISSN
- 21869057
- 00261165
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- NDL書誌ID
- 023882616
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- 本文言語コード
- en
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- データソース種別
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- JaLC
- NDL
- Crossref
- CiNii Articles
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- 抄録ライセンスフラグ
- 使用不可