Evaluating the accuracy and uncertainty of atmospheric and wave model hindcasts during severe events using model ensembles

Ali Abdolali,Avichal Mehra,Andre Van Der Westhuysen,Aron Roland,Saeed Moghimi,Zaizhong Ma

doi:10.1007/s10236-020-01426-9

Abstract

Various uncertainties exist in a hindcast due to the inabilities of numerical models to resolve all the complicated atmosphere-sea interactions, and the lack of certain ground truth observations. Here, a comprehensive analysis of an atmospheric model performance in hindcast mode (Hurricane Weather and Research Forecasting model—HWRF) and its 40 ensembles during severe events is conducted, evaluating the model accuracy and uncertainty for hurricane track parameters, and wind speed collected along satellite altimeter tracks and at stationary source point observations. Subsequently, the downstream spectral wave model WAVEWATCH III is forced by two sets of wind field data, each includes 40 members. The first ones are randomly extracted from original HWRF simulations and the second ones are based on spread of best track parameters. The atmospheric model spread and wave model error along satellite altimeters tracks and at stationary source point observations are estimated. The study on Hurricane Irma reveals that wind and wave observations during this extreme event are within ensemble spreads. While both Models have wide spreads over areas with landmass, maximum uncertainty in the atmospheric model is at hurricane eye in contrast to the wave model.

Highlights

The frequency and destructiveness of coastal storms have required improving the accuracy of numerical weatherResponsible Editor: Diana GreensladeThis article is part of the Topical Collection on the 16th International Workshop on Wave Hindcasting and Forecasting in Melbourne, AU, November 10–15, 20192 I.M
We provide an exploratory method to assess the similarity between observations and Hurricane Weather Research and Forecasting (HWRF)/WW3 model estimates which is general enough to be useful across many geophysical variables
Our analysis is done for the U10 and Hs observations in the vicinity of hurricane cone and far field observations separately

Summary

Introduction

The frequency and destructiveness of coastal storms have required improving the accuracy of numerical weatherResponsible Editor: Diana GreensladeThis article is part of the Topical Collection on the 16th International Workshop on Wave Hindcasting and Forecasting in Melbourne, AU, November 10–15, 20192 I.M. The frequency and destructiveness of coastal storms have required improving the accuracy of numerical weather. National Ocean Service, Silver Spring, MD, USA 5 University Corporation for Atmospheric Research (UCAR), Boulder, CO, USA prediction models, incorporating three other major strategies: (1) data assimilation, (2) ensemble modeling, and (3) atmospheric-wave-surge-hydrological coupling. The coupling of atmospheric, ocean wave, surge, and hydrological models on high-resolution numerical grids has improved model accuracy by better representing nearshore/inland geometries and physics (Moghimi et al 2020). Coupling reflects the dynamic feedbacks of model components, and improves our understanding of such a complicated system. High Performance Computing (HPC) facilitates the computational speed of the aforementioned modeling systems. Determining the damage caused by hurricanes using such numerical models requires a statistical evaluation of uncertainty

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