nerc.ac.uk

Tide-surge adjoint modeling: A new technique to understand forecast uncertainty

Wilson, Chris; Horsburgh, Kevin J.; Williams, Jane; Flowerdew, Jonathan; Zanna, Laure. 2013 Tide-surge adjoint modeling: A new technique to understand forecast uncertainty. Journal of Geophysical Research: Oceans, 118 (10). 5092-5108. 10.1002/jgrc.20364

Before downloading, please read NORA policies.
[img]
Preview
Text
jgrc20364_Wilson.pdf - Published Version

Download (1MB) | Preview

Abstract/Summary

For a simple dynamical system, such as a pendulum, it is easy to deduce where and when applied forcing might produce a particular response. However, for a complex nonlinear dynamical system such as the ocean or atmosphere, this is not as obvious. Knowing when or where the system is most sensitive, to observational uncertainty or otherwise, is key to understanding the physical processes, improving and providing reliable forecasts. We describe the application of adjoint modeling to determine the sensitivity of sea level at a UK coastal location, Sheerness, to perturbations in wind stress preceding an extreme North Sea storm surge event on 9 November 2007. Sea level at Sheerness is one of the most important factors used to decide whether to close the Thames Flood Barrier, which protects London. Adjoint modeling has been used by meteorologists since the 1990s, but is a relatively new technique for ocean modeling. It may be used to determine system sensitivity beyond the scope of ensemble modeling and in a computationally efficient way. Using estimates of wind stress error from Met Office forecasts, we find that for this event total sea level at Sheerness is most sensitive in the 3 h preceding the time of its unperturbed maximum level and over a radius of approximately 300 km. We also find that the pattern of sensitivity follows a simple sequence when considered in the reverse-time direction.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1002/jgrc.20364
ISSN: 21699275
Additional Keywords: sea level; adjoint; surge; sensitivity; ensemble; tide
Date made live: 23 Dec 2013 11:34 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/504367

Actions (login required)

View Item View Item

Document Downloads

Downloads for past 30 days

Downloads per month over past year

More statistics for this item...