Evaluation of WRF planetary boundary layer parameterization schemes for simulation of monsoon depressions over India
This study evaluates the fidelity of five planetary boundary layer (PBL) parameterization schemes in the advanced weather research and forecasting model for simulating monsoon depressions (MDs) over India. Five PBL schemes include; nonlocal first-order medium-range forecasting (MRF) and Yonsei University (YSU); hybrid first-order Asymmetric Convective Model version 2 (ACM2), and local one-and-a-half-order Bougeault–Lacarrére (BouLac) and Mellor–Yamada–Nakanishi–Niino (MYNN2). PBL schemes show significant impact on rainfall along with dynamical and thermodynamical parameters associated with MDs at the surface as well as at the upper levels. MRF simulates a relatively shallower, warmer and drier boundary layer compared to others. Results reveal that strong upper-level divergence and high moisture content within the lower levels are favorable for the occurrence of heavy rain associated with MDs. However, stronger wind shear within the mid-troposphere weakens the system and reduces the rain intensity. Based on the results and keeping the rainfall product in view, it is found that nonlocal PBL schemes (MRF and ACM2) have better forecast skills score than local PBL schemes (BouLac and MYNN2) over the Indian region.
The authors want to express their gratitude to the Indian Meteorological Department (IMD) and National Aeronautics and Space Administration (NASA)-Precipitation Measurement Mission (GPM) for providing the daily rainfall data, National Centers for Environmental Prediction (NCEP)–National Oceanic and Atmospheric Administration (NOAA) for initial and boundary condition, European Center for Medium-Range Weather Forecasts (ECMWF) for providing high resolution reanalysis data (i.e., ERA5) for validation (Contains modified Copernicus Climate Change Service Information), and National Centre for Atmospheric Research (NCAR) for using their WRF–ARW model for carrying out this study. We are thankful for the support of Indian Institute of Technology Bhubaneswar, Department of Science and Technology (DST), Government of India (RP-132) and Ministry of Earth Sciences (MoES), Government of India (RP088) for carrying out this research work. Figures are created with MATLAB (Version 2015a).
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