Comparison of HIPOCAS and ERA wind and wave reanalyses in the North Atlantic Ocean. (15th January 2016)

• Record Type: Journal Article
• Authors: Campos, R.M.; Guedes Soares, C.
• Is Part Of: Ocean engineering. Volume 112(2016)
• Page Start: 320
• Page End: 334
• Publication Date: 2016-01-15
• Subjects: Wind-wave hindcasts -- Reanalysis assessment -- Extreme events -- North Atlantic Ocean; Ocean engineering -- Periodicals; Ocean engineering; Periodicals; 620.4162
• DOI: 10.1016/j.oceaneng.2015.12.028
• Languages: English
• ISSNs: 0029-8018

Abstract

Abstract: Two pairs of comparisons between HIPOCAS and ERA reanalysis are performed in this paper. HIPOCAS is a hindcast developed under a European project and it is the result of the wave model WAM forced by REMO surface winds in the North Atlantic. ERA-40 and ERA-Interim were developed by the European Centre for Medium-Range Weather Forecasts, ECMWF, adopting the wave model WAM, covering the whole globe. A quick introductory comparison of HIPOCAS against ERA-40 is initially provided, which are hindcasts produced almost at the same time with common features. The main analysis covers a detailed comparison of HIPOCAS and ERA-Interim, which can be considered an update of ERA-40, followed by a comparison of both datasets against satellite data. Wind speed and significant wave height are the two variables considered. In order to compare the described wind and wave datasets, a common period and area were defined, with latitudes between 20° and 68° North and longitudes between 50° and 0° West, from 1979 till 2001. The differences for the whole dataset and for extreme events (upper percentiles) are calculated. A spatial and time integration is applied to determine where and when the main differences between hindcasts occur. The results show a relatively good agreement between HIPOCAS and both ERA-40 and ERA-Interim reanalysis for calm and moderate weather conditions. There is a large increase of the differences under extreme conditions, occurring mainly during the winter at mid-high latitudes. ERA-Interim presents the best results against measurements but suggests some underestimation under extreme events at mid-high latitudes. HIPOCAS tends to overestimate the measurements and over-predict both ERA reanalyses in the range of extreme values. Highlights: This paper compares two wind-wave hindcasts, HIPOCAS and ERA-40, in the North Atlantic. HIPOCAS is the result of the wave model WAM-cicle4 forced by REMO surface wind fields. ERA-40, developed by the ECMWF, resulted from the WAM model covering the whole globe. In order to compare the described data sets, the coincident area was defined. The differences in the means and for the 99% quantiles were calculated.