An improved potential intensity estimate for Bay of Bengal tropical cyclones
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An improved potential intensity estimate for Bay of Bengal tropical cyclones Russell H. Glazer1 · M. M. Ali2,3 Received: 5 December 2019 / Accepted: 1 September 2020 © Springer Nature B.V. 2020
Abstract The Bay of Bengal (BoB) is the most dangerous tropical cyclone (TC) region to humans in the world due to a combination of geographical and environmental factors. TC potential intensity (PI) estimates are a useful forecasting tool for evaluating favorable thermodynamic conditions for TC intensification; however, it assumes an idealized environment which omits several TC–environmental interactions. The present study compares the PI calculated using the SST (SST-PI) and the PI calculated taking into account ocean surface cooling and vertical wind shear (Environmental-PI) to the intensification rates of BoB TCs. A significant improvement is found in terms of explained variance when using Env-PI (13.5%) rather than SST-PI (3.5%). For slower moving TCs, the improvement is larger between Env-PI (25.5%) and SST-PI (4.9%). This study demonstrates that including an estimate of both oceanic and dynamical TC interactions in PI estimates lead to an improved estimate of future TC intensification in the BoB. Keywords Bay of Bengal · Tropical cyclones · Potential intensity
1 Introduction The North Indian Ocean (NIO) tropical cyclone (TC) basin stretches over two large bodies of water, the Arabian Sea (AS) and Bay of Bengal (BoB) that straddle the Indian subcontinent with the majority of NIO TC activity occurring in the BoB. Eight of the ten deadliest TCs in recorded history have originated from the NIO (WMO 2011) and of those seven occurred in the BoB. While TCs generally occur more frequently in other Northern Hemisphere TC basins TCs originating in the BoB basin pose the greatest human risk, in part because of the location of numerous population centers in coastal regions vulnerable to storm surge flooding, coupled with a relatively high probability of landfall due to geography. In light of this, the need to develop and improve TC forecasting techniques in the BoB cannot be understated. * Russell H. Glazer [email protected] 1
Abdus Salam International Centre for Theoretical Physics, Trieste, Italy
2
Center for Ocean‑Atmosphere Prediction Studies, Florida State University, Tallahassee, FL, USA
3
AP Disaster Management Authority, Kunchanapalli, India
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Natural Hazards
The potential intensity of a TC is defined as the theoretical maximum intensity attained by a TC under ideal conditions and has been derived using several different approaches in the past literature (Emanuel 1988 1995; DeMaria and Kaplan 1994; Holland 1997; Zeng et al. 2007). The potential intensity steady-state model proposed in Emanuel (1988 1995from this point referred to as PI), describe TCs as Carnot cycle heat engines in which latent heat energy extracted from the sea surface can be used to generate kinetic energy, which is then balanced by frictional dissipation. The sea surface temperature (SST) along with outflow layer te
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