Understanding Tropical Cyclone Oceanatmosphere Interaction Over North Indian Ocean Using Coupled Hwrf Hycom Modeling System and Prediction of Associated Storm Surge

Abstract

Globally considered as one of the most devastating natural hazards, tropical cyclones newline(TCs) have grabbed a lot attention from the scientific and the forecaster communities for newlinewhich the TC prediction has been improved considerably in the recent years. However, newlinethe intensity prediction needs substantial improvement. Ocean being the primary energy newlinesource to TCs, upon coupling with the atmospheric model component for TC prediction, newlinecan have the ability to improve the intensity as well as track prediction and also to newlinedevelop the understanding of air-sea interaction in TC environment that can be beneficial newlineto the future scientific advancements. In this thesis, the ocean component Hybrid newlineCoordinate Ocean Model (HYCOM) is coupled to high resolution meso-scale model newlineHurricane Weather Research Forecasting (HWRF) to simulate TCs and to understand the newlineimpact of coupling in improving TC prediction. Taking 3 pre- and 3 post-monsoon TCs, newlinean update of realistic sea surface temperature (SST) in HWRF model shows improvement newlinein intensity prediction significantly where the track improvement is marginal. The newlinestructural prediction is also improved with better SST presentation in the model. Then, to newlineunderstand different ocean condition impacts on TCs, HWRF-HYCOM coupled newlinemodeling system is used in idealized set up considering different Bay of Bengal (BoB) newlineconditions to initialize the ocean. Eight different climatological mean temperaturesalinity newlineprofiles in the BoB are used to initialize the idealized horizontally homogeneous newlineocean representing pre- and post-monsoon conditions over northern, central and southern newlineBoB and also averaged over the entire bay. The strongest storm is formed in the southern newlineBoB pre-monsoon case which has the highest initial SST and heat content relative to the newline26°C isotherm. In all cases, intensity evolution was closely related to the time series of newlineenthalpy flux averaged over the inner-core region of the storm where this flux is the newlinelargest.