Sensitivity of simulation of rapidly intensified tropical cyclones to local planetary boundary layer scheme

Simulation of stronger convergence of angular momentum in the boundary layer by the turbulent kinetic energy planetary boundary layer (PBL) schemes causes faster spin-up of the tropical cyclone (TC) vortex. We have conducted two experiments using local turbulent kinetic energy-based PBL parameterization schemes viz. Mellor-Yamada-Janjic (MYJ) and Bougeault-Lacarrere (Boulac) schemes have been used to analyze their impacts on the simulation of three TCs formed over the North Indian Ocean. The high-resolution (2 km) reanalysis has been developed by 6 hourly cyclic data assimilation using the Weather Research and Forecasting model (WRF) and data assimilation (WRFDA). The impact of PBL schemes has been investigated by comparing the developed reanalysis with the observations and IMD reanalysis. MYJ experiment showed lower bias in the simulation of genesis stage winds, variation in minimum sea level pressure, and rainfall distribution compared to the Boulac experiment. For TC Fani, Boulac experiments have more bias in the simulation of potential temperature at the lower troposphere. The Boulac experiment captured the high wind speed at the maximum intensity (MI) stage and the drastic increment in wind speed during the rapid intensification (RI). Both the schemes overestimated the RI of TC Fani. Whereas, for post-monsoon TCs Luban and Ockhi, the RI was more precisely captured by the Boulac experiment compared to the MYJ experiment. The successful simulation of intense wind speed at the MI stages by the Boulac experiment is attributed to the simulation of higher moisture flux and stronger updraft in the Boulac experiment.