Effect of land -atmosphere interactions on mesoscale convection and precipitation over the Indian monsoon region
Abstract
Whether enhanced land surface representation can improve the ability of mesoscale weather forecast models is examined in this dissertation by performing numerical simulations on the convective systems over the Indian monsoon region. Three types of mesoscale convection systems were examined at meso alpha, beta and gamma scales using the Weather Research and Forecasting model (WRF). The first task analyzed a localized heavy rain event associated with individual mesoscale convective cells. The hypothesis tested is: Observed deep convection and heavy rain events over the Indian monsoon region can be better simulated by mesoscale models with accurate land use land cover representation. The second task focused on three different land-falling tropical depressions. These monsoon depressions (MDs) occurred in August 2006 over the Bay of Bengal. The hypothesis tested is: Antecedent soil moisture and land surface representation can affect the inland mesoscale convection and rainfall associated with the land falling MDs. The third task dealt with three thunderstorm events over eastern India observed during the Severe Thunderstorms-Observations and Regional Modeling field program in 2006 and 2007. The hypothesis tested is: Convection initiation and mesoscale precipitation is sensitive to the prescription of land surface processes in coupled mesoscale models over the Indian monsoon region. Study results indicate: (i) Accurate representation of land surface processes in a mesoscale model leads to more realistic simulation of the timing, location, and amount of convection and mesoscale precipitation in numerical weather forecast models over the Indian monsoon region; (ii) Wetter antecedent land conditions lead to stronger monsoon depressions; (iii) land surface feedbacks in mesoscale models are sensitive to the convection parameterizations.
Degree
Ph.D.
Advisors
Niyogi, Purdue University.
Subject Area
Meteorology|Atmospheric sciences
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