Accession Number : ADA480229

Title :   An Optimal Definition for Ocean Mixed Layer Depth

Descriptive Note : Journal article

Corporate Author : SVERDRUP TECHNOLOGY INC STENNIS SPACE CENTER MS

Personal Author(s) : Kara, A. B. ; Rochford, Peter A. ; Hurlburt, Harley E.

PDF Url : ADA480229

Report Date : 15 JUL 2000

Pagination or Media Count : 20

Abstract : A new method is introduced for determining ocean isothermal layer depth (ILD) from temperature profiles and ocean mixed layer depth (MLD) from density profiles that can be applied in all regions of the world's oceans. This method can accommodate not only in situ data but also climatological data sets that typically have much lower vertical resolution. The sensitivity of the ILD and MLD to the temperature difference criteria used in the surface layer depth definition is discussed by using temperature and density data, respectively: (1) from 11 ocean weather stations in the northeast Pacific and (2) from the World Ocean Atlas 1994. Using these two data sets, a detailed statistical error analysis is presented for the ILD and MLD estimation by season. MLD variations with location due to temperature and salinity are properly accounted for in the defining density (Delta sigma sub t) criterion. Overall, the optimal estimate of turbulent mixing penetration is obtained using a MLD definition of Delta T = 0.8 C, although in the northeast Pacific region the optimal MLD criterion is found to vary seasonally. The method is shown to produce layer depths that are accurate to within 20 m or better in 85% or more of the cases. The MLD definition presented in this investigation accurately represents the depth to which turbulent mixing has penetrated and would be a useful aid for validation of one-dimensional bulk mixed layer models and ocean general circulation models with an embedded mixed layer.

Descriptors :   *DENSITY, *TEMPERATURE, *DEPTH, *MIXED LAYER(MARINE), REPRINTS, SEASONAL VARIATIONS, SALINITY, MARINE CLIMATOLOGY

Subject Categories : Physical and Dynamic Oceanography

Distribution Statement : APPROVED FOR PUBLIC RELEASE