Numerical Simulation of Tropical Cyclone Mora Using a Regional Coupled Ocean-Atmospheric Model

Agrawal, Nishtha; Pandey, Vivek Kumar; Kumar, Prashant

doi:10.1007/s00024-020-02563-4

Cited by 2 publications

(1 citation statement)

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“…Regional-scale coupled predictions are already operational for some TC cases in the Atlantic and North Pacific (Biswas et al, 2018;Jin et al, 2013;Saito et al, 2006), although the models used in these studies do not explicitly resolve convection. Fewer studies assess air-sea coupled models in the Bay of Bengal; the majority use mesoscale models with parameterised convection (Agrawal et al, 2020;Baisya et al, 75 2020;Greeshma et al, 2019;Yesubabu et al, 2020). They show a high sensitivity of TCs to air-sea interactions (Prakash & Pant, 2017), ocean mixed layer depth (Yesubabu et al, 2020) and ocean eddies (Anandh et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Simulations of Bay of Bengal tropical cyclones in a regional convection-permitting atmosphere–ocean coupled model

Saxby

Crook

Peatman

et al. 2021

Preprint

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Abstract. Tropical cyclones (TCs) in the Bay of Bengal can be extremely destructive when they make landfall in India and Bangladesh. Accurate prediction of their track and intensity is essential for disaster management. This study evaluates simulations of Bay of Bengal TCs using a regional convection-permitting atmosphere-ocean coupled model. The Met Office Unified Model atmosphere-only configuration (4.4 km horizontal grid spacing) is compared with a configuration coupled to a three-dimensional dynamical ocean model (2.2 km horizontal grid spacing). Simulations of six TCs from 2016–2019 show that both configurations produce accurate TC tracks for lead times of up to 6 days before landfall. Both configurations underestimate high wind speeds and high rain rates, and overestimate low wind speeds and low rain rates. The ocean-coupled configuration improves landfall timing predictions and reduces wind speed biases relative to observations outside the eyewall but underestimates maximum wind speeds in the eyewall for the most intense TCs. The coupled configuration produces weaker TCs than the atmosphere-only configuration, consistent with lower sea surface temperatures in the coupled model and an overestimated cooling response in TC wakes. Both model configurations accurately predict rain rate asymmetry, suggesting a good representation of TC dynamics. Much of the rain rate asymmetry variation in the simulations is related to wind shear variations, with a preference for higher rain rates in the down-shear left quadrant.

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