Accession Number:

ADA455207

Title:

Stability-Dependent Exchange Coefficients for Air-Sea Fluxes

Descriptive Note:

Journal article

Corporate Author:

NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV

Report Date:

2004-10-27

Pagination or Media Count:

16.0

Abstract:

This study introduces exchange coefficients for wind stress Csub D, latent heat flux Csub L, and sensible heat flux Csub S over the global ocean. They are obtained from the state-of-the-art Coupled Ocean-Atmosphere Response Experiment COARE bulk algorithm version 3.0. Using the exchange coefficients from this bulk scheme, Csub D, Csub L, and Csub s are then expressed as simple polynomial functions of air-sea temperature difference Tsub a-Tsub s where air temperature Tsub a is at 10 m, wind speed Vsub a is at 10 m, and relative humidity RH is at the air-sea interface-to parameterize stability. The advantage of using polynomial based exchange coefficients is that they do not require any iterations for stability. In addition, they agree with results from the COARE algorithm but at 5 times lower computation cost, an advantage that is particularly needed for ocean general circulation models OGCMs and climate models running at high horizontal resolution and short time steps. The effects of any water vapor flux in calculating the exchange coefficients are taken into account in the polynomial functions, a feature that is especially important at low wind speeds e.g., Vsub a 5 m sexp -1 because air-sea mixing ratio difference can have a major effect on the stability, particularly in tropical regions. Analyses of exchange coefficients demonstrate the fact that water vapor can have substantial impact On air-sea exchange coefficients at low wind speeds. An example application of the exchange coefficients from the polynomial approach is the recalculation of climatological mean wind stress magnitude from 40-yr European Centre for Medium-Range Weather Forecasts ECMWF Re-Analysis ERA-40 data in the North Pacific Ocean over 1979-2002.

Subject Categories:

  • Meteorology
  • Physical and Dynamic Oceanography

Distribution Statement:

APPROVED FOR PUBLIC RELEASE