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Observations indicative of rain-induced double diffusion in the ocean surface boundary layer

Walesby, K.
; 
Vialard, J.
; 
Minnett, P. J.
; 
Callaghan, A. H.
; 
Ward, B.
Repository DOI
Publication Date
2015-05-19
Keywords
double diffusion, surface ocean boundary layer, air-sea interaction profiler, thermohaline staircase, north-atlantic, salt fingers, fluxes, turbulence, stratification, microstructure, impact
Type
Article
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Citation
Walesby, K. Vialard, J.; Minnett, P. J.; Callaghan, A. H.; Ward, B. (2015). Observations indicative of rain-induced double diffusion in the ocean surface boundary layer. Geophysical Research Letters 42 (10), 3963-3972
Abstract
Double diffusion can result in the formation of thermohaline staircases, typically observed in the ocean interior. The observations presented here were acquired in the ocean surface boundary layer with the autonomous microstructure Air-Sea Interaction Profiler. An intense rain event (rainfall rates of up to 35mm/h) resulted in cooler, fresher water (up to 0.15practical salinity unit (psu) over the upper 7-10m) overlaying warmer, saltier water, a situation potentially conducive to double-diffusive mixing. Although not as crisp as interfaces in the interior ocean because of elevated background mixing, a total of 303 thermohaline interfaces were detected within and at the base of the fresh layer, with mean changes in temperature (T) and salinity (S) across interfaces of 20 x 10(-3 degrees)C and 22 x 10(-3)psu, respectively. These results call for new studies to disambiguate whether such interfaces are formed through double-diffusive mixing or shear instabilities and understand any long-term impacts on near-surface stratification.
Funder
Publisher
Wiley-Blackwell
Publisher DOI
10.1002/2015gl063506
Rights
Attribution-NonCommercial-NoDerivs 3.0 Ireland
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Externally hosted open access publications with University of Galway authors (2)