Preprints
https://doi.org/10.5194/nhess-2020-299
https://doi.org/10.5194/nhess-2020-299

  12 Oct 2020

12 Oct 2020

Review status: a revised version of this preprint was accepted for the journal NHESS and is expected to appear here in due course.

Improving our understanding of wind extremes from Bangladesh tropical cyclones: insights from a high-resolution convection-permitting numerical model

Hamish Steptoe1 and Theo Economou2,1 Hamish Steptoe and Theo Economou
  • 1Met Office, FitzRoy Road, Exeter, EX1 3PB, UK
  • 2College of Engineering, Mathematics and Physical Sciences, University of Exeter, UK

Abstract. We use high resolution (4.4 km) numerical simulations of tropical cyclones to produce exceedance probability estimates for extreme wind (gust) speeds over Bangladesh. For the first time, we estimate equivalent return periods up to and including a 1-in-200 year event, in a spatially coherent manner over all of Bangladesh, by using generalised additive models. We show that some northern provinces, up to 200 km inland, may experience conditions equal to or exceeding a very severe cyclonic storm event (maximum wind speeds in ≥ 64 knots) with a likelihood equal to coastal regions less than 50 km inland. For the most severe super cyclonic storm events (≥ 120 knots), event exceedance probabilities of 1-in-100 to 1-in-200 events remain limited to the coastlines of southern provinces only. We demonstrate how the Bayesian interpretation of the generalised additive model can facilitate a transparent decision-making framework for tropical cyclone warnings.

Hamish Steptoe and Theo Economou

 
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Hamish Steptoe and Theo Economou

Data sets

Bangladesh - Tropical Cyclone Historical Catalogue Hamish Steptoe, Nick Savage, Saeed Sadri, Kate Salmon, Zubair Maalick, and Stuart Webster https://doi.org/10.5281/zenodo.3600201

Model code and software

MetOffice/IKI-Oasis-Bangladesh Hamish Steptoe https://doi.org/10.5281/zenodo.3953772

Hamish Steptoe and Theo Economou

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Latest update: 11 Apr 2021
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Short summary
We use high resolution computer simulations of tropical cyclones to investigate extreme wind speeds over Bangladesh. We show that some northern provinces, up to 200 km inland, may experience conditions equal to or exceeding a very severe cyclonic storm event with a likelihood equal to coastal regions less than 50 km inland. We hope that these kilometre scale hazard maps facilitate one part of the risk assessment chain to improve local ability to make effective risk management decisions.
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