The Impact of Wind Gusts on the Ocean Thermal Skin Layer

Type Article
Date 2019-10
Language English
Author(s) Zappa Christopher J.1, Laxague Nathan J.M.1, Brumer Sophia2, Anderson Steven P.3
Affiliation(s) 1 : Lamont‐Doherty Earth ObservatoryColumbia University Palisades NY ,USA
2 : Laboratoire d'Océanographie Physique et Spatiale, UMR 6523 IFREMER‐CNRS‐IRD‐UBO Plouzané ,FRANCE
3 : Areté Associates Arlington VA ,USA
Source Geophysical Research Letters (0094-8276) (American Geophysical Union (AGU)), 2019-10 , Vol. 46 , N. 20 , P. 11301-11309
DOI 10.1029/2019GL083687
WOS© Times Cited 2
Abstract

The thermodynamic and emissive properties of the ocean thermal skin layer are crucial contributors to air‐sea heat flux. In order to properly observe ocean surface temperature without disturbing any delicate fluid mechanical processes, thermal infrared imaging is often used. However, wind impacting the ocean surface complicates the extraction of meaningful information from thermal imagery; this is especially true for transient forcing phenomena such as wind gusts. Here, we describe wind gust‐water surface interaction through its impact on skin layer thermal and emissive properties. Two key physical processes are identified: (1) the growth of centimeter‐scale wind waves, which increases interfacial emissivity and (2) microscale wave breaking and shear, which mix the cool skin layer with warmer millimeter‐depth water and increase the skin temperature. As more observations are made of air‐sea interaction under transient forcing, the full consideration of these processes becomes increasingly important.

Key Points

Wind gusts produce transient ocean skin layer thermal fronts that propagate near the observed wind speed

Wind gust fronts disrupt the ocean thermal skin layer due to microbreaking and increase emissivity due to capillary‐gravity wave growth

Following wind gust front passage, capillary‐gravity wave relaxation reduced surface emissivity faster than the cool skin was restored

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