An index of wind–wave coupling and its global climatology. (3rd November 2015)

• Record Type: Journal Article
• Authors: Jiang, Haoyu; Chen, Ge; Yu, Fangjie
• Is Part Of: International journal of climatology. Volume 36:Number 8(2016)
• Page Start: 3139
• Page End: 3147
• Publication Date: 2015-11-03
• Subjects: surface waves -- wind–wave interaction -- wave direction -- altimeter; Climatology -- Periodicals; Climat -- Périodiques; Climatologie -- Périodiques; 551.605
• DOI: 10.1002/joc.4542
• Languages: English
• ISSNs: 0899-8418

Abstract

ABSTRACT: Using the fully developed wind–wave relation and simultaneous data of surface wind speed and wave height, an index of wind–wave coupling is presented. The validity of this index is demonstrated by comparing it to other wind–wave indices using 45‐year European Centre for Medium‐Range Weather Forecasts Re‐Analysis (ERA‐40). The comparison shows that the angle between wind and wave directions need not be considered in practice when mapping climatology of wind–wave interaction, and the rationality behind it is explained from a statistical point of view. The results also indicate that probability‐based indices are not robust enough to represent wave climate. A global climatology of this index is developed using both ERA‐40 and jointly‐calibrated altimeter data. Its spatial distributions show that the wind–wave coupling is strong in the mid‐latitudes while weak in the low latitudes except for the trade‐wind regions. Mixing of wind‐sea and swell is found to be common in the ocean, especially in the trade‐wind region, where two‐way momentum transfer may exist because the directions of wind‐sea and swell are different. The weakly coupled regions usually have a clear preference for the eastern sides and low latitudes of ocean basins, because the eastward swells there are mainly from the storms in westerlies. However, in the Pacific Ocean, trade‐wind‐generated swells may propagate westward, causing western side to be also weakly coupled.