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Observations indicative of rain‐induced double diffusion in the ocean surface boundary layer
Author(s) -
Walesby K.,
Vialard J.,
Minnett P. J.,
Callaghan A. H.,
Ward B.
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl063506
Subject(s) - thermohaline circulation , stratification (seeds) , mixing (physics) , temperature salinity diagrams , salinity , diffusion , geology , boundary layer , mixed layer , argo , surface layer , climatology , oceanography , environmental science , atmospheric sciences , layer (electronics) , materials science , mechanics , physics , thermodynamics , seed dormancy , botany , germination , quantum mechanics , dormancy , composite material , biology
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 35 mm/h) resulted in cooler, fresher water (up to 0.15 practical salinity unit (psu) over the upper 7–10 m) 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 × 10 −3∘ C and 22 × 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.