Diagnostic study of generalized moist potential vorticity in a non-uniformly saturated atmosphere with heavy precipitation

Authors

  • Zhaoming Liang,

    1. Graduate School of Chinese Academy of Sciences and Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
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  • Chungu Lu,

    Corresponding author
    1. Cooperative Institute for Research in the Atmosphere, Fort Collins, Colorado, USA
    2. NOAA/Earth System Research Laboratory, Boulder, Colorado, USA
    • Physical and Dynamic Meteorology, Div. of Atmospheric & Geospace Sciences (AGS), US National Science Foundation, 4201 Wilson Blvd., Suite 675.25, Arlington, VA 22230, USA.
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  • Edward I. Tollerud

    1. NOAA/Earth System Research Laboratory, Boulder, Colorado, USA
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Abstract

A Meiyu front accompanied by a band of heavy precipitation in East Asia is typically characterized by a much larger moisture gradient than temperature gradient. Many previous studies have suggested use of equivalent potential temperature as a thermodynamic variable under this circumstance. However, dynamic variables coupled with such a thermodynamic variable, e.g. a derived moist potential vorticity (MPV) based on equivalent potential temperature, does not provide useful dynamic insight into these systems. In this study, generalized moist potential vorticity (GMPV) is derived based on a generalized form of potential temperature. Diagnoses of numerical simulations for three typical Meiyu rainfall events show that GMPV provides remarkably accurate tracking of rainfall location, suggesting its potential use as a dynamic tracer for heavy rainfall events such as Meiyu rain bands. Copyright © 2010 Royal Meteorological Society

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