Environmental controls on tropical mesoscale convective system precipitation intensity

Climate & Radiation Laboratory Virtual Seminar Series 

  

Kathleen Schiro 

Dept. of Environmental Sciences, University of Virginia 

 

 

Environmental controls on tropical mesoscale convective system precipitation intensity 

  

In this talk, I will present new statistics providing a physical basis for understanding environmental factors controlling heavy precipitation events in tropical continental and oceanic regions using multiple independent satellite and reanalysis datasets. First, a sharp, nonlinear relationship between column-integrated water vapor and precipitation intensity among detected mesoscale convective systems (MCS) will be presented and discussed within the context of previous work, consistent with nonlinear increases in estimated plume buoyancy. MCS precipitation intensity increases sharply with both increasing boundary layer and lower free tropospheric moisture, with the largest precipitation maximum (Pmax) originating in MCS environments with a peak in LFT moisture near 750 mb. These relationships exhibit strikingly similar behavior among tropical land and ocean regions. 

Additional dynamic and thermodynamic factors controlling precipitation intensity will also be discussed. While the moisture-Pmax relationship depends strongly on mean tropospheric temperature, it does not depend on sea surface temperature over ocean or surface air temperature over land. Other Pmax dependent factors include system radius, the number of convective cores, low-level wind shear, and the large-scale vertical velocity. Larger systems typically contain wider convective cores and higher Pmax, consistent with increased protection from dilution due to dry air entrainment and reduced re-evaporation of precipitation. Additionally, stronger large-scale ascent generally supports greater precipitation production. Temporal lead-lag analysis detects anomalous moisture in the lower-middle troposphere leading MCS detection by up to 6 hours; however, additional analysis is needed to understand factors specific to controlling convection organization and upscale growth. I will conclude by sharing ideas for work and collaboration.   

Short Bio: 

Kathleen Schiro is an Assistant Professor in the Department of Environmental Sciences at the University of Virginia. Prof. Schiro earned her B.A. in Earth and Planetary Science at Johns Hopkins University in 2011 and her PhD in Atmospheric and Oceanic Sciences at the University of California, Los Angeles in 2017. Prior to joining the faculty at UVA, Prof. Schiro was a postdoctoral scholar at the Jet Propulsion Laboratory, California Institute of Technology. As an atmospheric scientist, she specializes in studying clouds, convection, and precipitation across scales in the tropics using field campaign data, satellite observations, and climate models.  

 

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613 Seminar Series Coordinators  

mailto:Reed.Espinosa@nasa.gov  

mailto:Jie.Gong@nasa.gov  

  

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