Study on Effect of Energy Fluxes in Relation to the Movement and Intensity of Tropical Cyclones in the Bay of Bengal

Abstract

Comprehensive sensitivity analysis on physical parameterization schemes of Weather Research and Forecasting model (WRF v3.2.1) have been carried out for the effects of energy fluxes on the prediction of track and intensity of Tropical Cyclone Roanu, Hudhud and Mala those formed in the Bay of Bengal and crossed Bangladesh, Visakhapatnam of India and Myanmar coast during May 2016, October 2014 and April 2006 respectively. The initial and boundary conditions of tropical cyclone (TC) are drawn from the global operational analysis and forecast products of National Center for Environmental Prediction (NCEP-GFS) available for the public at 1°×1o resolution. The model was run by using Kessler (KS), Lin et al. (Lin), WSM3-class simple ice, Ferrier (FE), WSM6-class graupel and Thomson (TH) graupel microphysics (MP) schemes coupling with different cumulus parameterization (CP) schemes and different initial conditions. Kain-Fritsch (KF) and Betts-Miller-Janjic (BMJ) schemes have been used to study the effects of energy fluxes on the track of TC. The model domain consists of 8-24oN and 77-96oE and has 12 km horizontal resolution with 28 vertical sigma levels. The model was run for 96 and 72-h using initial conditions at 0000 UTC of 18 and 19 May 2016 for TC Roanu, 120 and 96-h using initial conditions of 0000 UTC of 8 and 9 October 2014 for TC Hudhud, and 120 and 96-h using initial conditions of 0000 UTC of 26 and 27 April 2006 for TC Mala. To examine the effect of energy fluxes on the movement of TC we have considered five different regions inside the model domain. The regions are R1 (22-26oN & 87-93oE), R2 (18-22oN & 81-85oE), R3 (14-18oN & 78-84oE), R4 (12-22oN & 85- 94oE) and R5 (17-22oN & 94-97oE). In this research the Convective available potential energy (CAPE), Convective inhibition (CIN), Downward long wave heat flux (DLHF), Downward shortwave heat flux (DSHF), Ground heat flux (GHF), latent heat flux (LH), moisture heat flux (QFX), Outgoing long wave radiation (OLR), and upward heat flux (HFX) have been analyzed in R1, R2, R3, R4 and R5 to observe the impact of these parameters for the movement of TC. The vertically integrated space averaged CAPE, CIN, DLHF, DSHF, OLR have found to decrease continuously for all MPs in combination with KF and BMJ schemes in a region where TC moves. These parameters have decreased for TC Roanu in R1, for TC Mala in R5 and TC Hudhud in R2. The QFX and LH have been increased in a region where TC moves.