Airborne measurements of surface wind and slope statistics over the ocean

TitleAirborne measurements of surface wind and slope statistics over the ocean
Publication TypeJournal Article
Year of Publication2019
AuthorsLenain L., Statom N.M, Melville W.K
Volume49
Pagination2799-2814
Date Published2019/11
Type of ArticleArticle
ISBN Number0022-3670
Accession NumberWOS:000494442600001
Keywordsair-sea interaction; breakers; breaking; evolution; instability; LiDAR; Lidars; meter; motion; observations; oceanography; reflectance; spectrum; waves; wind; wind stress; Wind waves
Abstract

As reported in 1954, more than a half century ago, C. Cox and W. Munk developed an empirical model of the slope distribution of ocean surface waves that has been widely used ever since to model the optical properties of the sea surface and is of particular importance to the satellite remote sensing community. In that work, the reflectance of sunlight was photographed from a Boeing B-17G bomber and was then analyzed. In this paper, surface slope statistics are investigated from airborne scanning topographic lidar data collected during a series of field experiments off the coast of California and in the Gulf of Mexico, over a broad range of environmental conditions, with wind speeds ranging from approximately 2 to 13 m s(-1). Unlike the reflectance-based approach of Cox and Munk, the slope distribution is computed by counting laser glints produced by specular reflections as the lidar is scanned over the surface of the ocean. We find good agreement with their measurements for the mean-square slope and with more recent (2006) results from Breon and Henriot that were based on satellite remote sensing. Significant discrepancies for the higher-order statistics are found and discussed. We also demonstrate here that airborne scanning lidar technology offers a viable means of remotely estimating surface wind speed and momentum flux.

DOI10.1175/jpo-d-19-0098.1
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