A 10-yr Climatology of Tibetan Plateau Vortices with NCEP Climate Forecast System Reanalysis

Journal of Applied Meteorology and Climatology - Tập 53 Số 1 - Trang 34-46 - 2014
Xinyuan Feng1, Changhai Liu2, Roy Rasmussen2, Guangzhou Fan1
1College of Atmospheric Sciences, Chengdu University of Information Technology/Plateau Atmosphere and Environment Key Laboratory of Sichuan Province, Chengdu, China
2Research Application Laboratory, National Center for Atmospheric Research,* Boulder, Colorado

Tóm tắt

AbstractA plateau vortex refers to a shallow meso-α-scale cyclonic vortex that is usually confined to near-surface levels (500 hPa) over the Tibetan Plateau during warm seasons. It is the major precipitation-producing weather system over the plateau, but the knowledge of its climatology and understanding of generation mechanisms are limited because of the lack of adequate observations in this harsh mountainous region. In this study, the high-resolution NCEP Climate Forecast System Reanalysis data have been used to perform a statistical survey of these vortices over 10 warm seasons (April–October of 2000–09). The purpose is to document their climatological features, including genesis, size, life cycle, propagation, and diurnal variation.Results show that ~103 plateau vortices occur on average every year. Most are detected from May through August, with the maximum monthly count in July. The primary area of origin exhibits a west–east orientation in correspondence with a large-scale confluence zone, and the most concentrated source lies in the area of 33°–36°N, 84°–90°E in the high elevated central and western plateau. Significant diurnal variations are observed, characteristic of a preferential genesis during late afternoon to evening hours and a late night dissipation peak. The vortex events have an average life span of ~15 h and an average horizontal dimension (effective diameter) of ~280 km. In accordance with the steering environmental flow, an overwhelming majority travel eastward with a mean translation speed of ~10 m s−1. A small fraction of systems (approximately nine cases annually) move off the plateau, predominantly from the eastern edge.

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Thông tin xuất bản

Journal of Applied Meteorology and Climatology

Tập 53 Số 1

34-46

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