Bay of Bengal cyclones Mora and Maarutha in regional atmospheric modeling system
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ORIGINAL ARTICLE
Bay of Bengal cyclones Mora and Maarutha in regional atmospheric modeling system Nishtha Agrawal1 · Vivek Kumar Pandey1 Received: 6 July 2020 / Accepted: 3 October 2020 © Springer Nature Switzerland AG 2020
Abstract The coastal region of India is exposed to nearly 7% of tropical cyclones occurring in the world. The large basin of Bay of Bengal incites cyclones with varying intensity that is capable enough to cause huge damage to life and money. To understand the underlying mechanism behind these TCs and enhance their forecast accuracy, it is essential to simulate them precisely using different numerical models by applying appropriate micro-physics, Cumulus Convection (CC) and Planetary Boundary Layer (PBL) schemes. The present study uses the Regional Atmospheric Modeling System (RAMS) to simulate TCs Mora and Maarutha in the Bay of Bengal region and associated landfall in Northeast India and Bangladesh. The study is an approach to investigate and analyze winds, precipitation and other dynamical variables associated with the formation of these cyclones by providing initial and boundary conditions from the NCEP-FNL (Final) operational global analysis data (6 hourly temporal and 1.0° spatial resolution). The model output is further nudged towards the observational soundings which are obtained from NCAR-ADP upper air observational dataset. Along with this, an attempt has been made to obtain the optimum configuration of distribution and intensity of a precipitation field to match observations. Keywords RAMS · Tropical cyclone · Landfall · Microphysics and cumulus convection
Introduction A Tropical Cyclone (TC) is a low-pressure system rotated by well-known coriolis effect with inwards surface winds which is originated over a tropical ocean (Lighthill 1998). It comprises of strong damaging vertical winds and very high precipitation near the eyewall. A mature TC is a fine example of a Carnot heat engine, except that the engine does no work on its environment; instead, the available work is locally dissipated and a fraction of the dissipated energy is recycled into the engine (Emanuel 2005). It gains its energy principally by heat transfer from the ocean with the large surface heat fluxes in and near the eyewall. As a natural hazard, a TC is one of the major threatening weather-related disasters that can cause loss of lives and considerable economic damages (Emanuel 2005; Bouwer 2011; Mendelsohn * Vivek Kumar Pandey [email protected] Nishtha Agrawal [email protected] 1
K Banerjee Centre of Atmospheric and Ocean Studies, University of Allahabad, Prayagraj 211002, India
et al. 2012). Therefore, given the nature of cyclone damage, it is imperative to track down a tropical cyclone well ahead to minimize the societal and economic impacts (Islam et al. 2015). The prediction skill of track and intensity of TCs has been improvised during the last several decades in India. This has been achieved with the help of advanced observational tools, modeling results and their assimilation. The models
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