title: An inconvenient sea truth: spread, steepness, and skewness of surface slopes.
abstract: Bréon and Henriot (BH) have collected eight million globally distributed satellite images of sunglitter, which yield a few simple, robust rules about the statistics of surface slopes: 1) constant angular spread, 2) linear steepness, and 3) sigmoid (near stepwise) skewness (all with respect to wind speed). Yet the information is sparse because it says nothing about time and space scales. The BH rules are an inconvenient sea truth, too fundamental to be ignored, too incomplete to be understood. With regard to BH rule 1 (BH:1), I suggest that the constant spread is associated with a wake-like geometry of the short gravities. Steepness linearity (BH:2) remains an enigma. Skewness (BH:3) appears to be correlated with a rather sudden onset of breaking for winds above 4 m s(-1). I do not think that skewness comes from parasitic capillaries. These are tentative conclusions; I look forward to intensive sea-going experiments over the next few years demolishing the proposed interpretations.
authors.affiliation: Scripps Institution of Oceanography, University of California, San Diego, California 92093, USA. wmunk@ucsd.edu
authors.forename: Walter
authors.initials: W
authors.lastname: Munk
mesh_terms: D008962:Models, Theoretical; D009792:Oceans and Seas; D012767:Ships; D013223:Statistics as Topic / Q000592:standards; D014872:Water Movements; D014919:Wind