A high-resolution hindcast of wind and waves for The North Sea, The Norwegian Sea and The Barents Sea

TL;DR

This study presents a high-resolution wind and wave hindcast for the North Sea, Norwegian Sea, and Barents Sea, improving upon ERA-40 reanalysis by capturing finer-scale features and reducing biases.

Contribution

It introduces a combined high-resolution atmospheric downscaling and wave hindcast methodology that enhances the accuracy of wind and wave predictions in northern seas.

Findings

Significant improvement in wind and wave height estimates over ERA-40.

Better reproduction of polar lows, though their full life cycle is not captured.

Reduction of biases in wind speed and wave height in the hindcast.

Abstract

A combined high-resolution atmospheric downscaling and wave hindcast based on the ERA-40 reanalysis covering the Norwegian Sea, the North Sea and the Barents Sea is presented. The period covered is from September 1957 to August 2002. The dynamic atmospheric downscaling is performed as a series of short prognostic runs initialized from a blend of ERA-40 and the previous prognostic run to preserve the fine-scale surface features from the high-resolution model while maintaining the large-scale synoptic field from ERA-40. The nested WAM wave model hindcast consists of a coarse 50 km model covering the North Atlantic forced with ERA-40 winds and a nested 10-11 km resolution model forced with downscaled winds. A comparison against in situ and satellite observations of wind and sea state reveals significant improvement in mean values and upper percentiles of wind vectors and the significant wave height over ERA-40. Improvement is also found in the mean wave period. ERA-40 is biased low in wind speed and significant wave height, a bias which is not reproduced by the downscaling. The atmospheric downscaling also reproduces polar lows, which can not be resolved by ERA-40, but the lows are too weak and short-lived as the downscaling is not capable of capturing their full life cycle.