Premium
Seasonality of submesoscale flows in the ocean surface boundary layer
Author(s) -
Buckingham Christian E.,
Naveira Garabato Alberto C.,
Thompson Andrew F.,
Brannigan Liam,
Lazar Ayah,
Marshall David P.,
George Nurser A. J.,
Damerell Gillian,
Heywood Karen J.,
Belcher Stephen E.
Publication year - 2016
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 - 10.1002/2016gl068009
Subject(s) - rossby number , potential vorticity , skewness , vorticity , geology , climatology , thermocline , geostrophic wind , stratification (seeds) , mixed layer , ekman transport , boundary current , rossby radius of deformation , ocean dynamics , rossby wave , atmospheric sciences , oceanography , ocean current , turbulence , meteorology , vortex , physics , upwelling , statistics , mathematics , seed dormancy , germination , botany , dormancy , biology
Abstract A signature of submesoscale flows in the upper ocean is skewness in the distribution of relative vorticity. Expected to result for high Rossby number flows, such skewness has implications for mixing, dissipation, and stratification within the upper ocean. An array of moorings deployed in the Northeast Atlantic for 1 year as part of the experiment of the Ocean Surface Mixing, Ocean Submesoscale Interaction Study (OSMOSIS) reveals that relative vorticity is positively skewed during winter even though the scale of the Rossby number is less than 0.5. Furthermore, this skewness is reduced to zero during spring and autumn. There is also evidence of modest seasonal variations in the gradient Rossby number. The proposed mechanism by which relative vorticity is skewed is that the ratio of lateral to vertical buoyancy gradients, as summarized by the inverse gradient Richardson number, restricts its range during winter but less so at other times of the year. These results support recent observations and model simulations suggesting that the upper ocean is host to a seasonal cycle in submesoscale turbulence.