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Air–Sea Flux Estimates And The 1997–1998 Enso Event

Abstract

Bulk formulae for wind stress, sensible and latent heat flux are presented that are suitable for strong mesoscale events such as westerly wind bursts that contribute to the El Niño-Southern Oscillation (ENSO). Their exchange coefficients for heat and momentum have a simple polynomial dependence on wind speed and a linear dependence on air–sea temperature difference. The accuracy of these formulae are validated with respect to air–sea fluxes estimated using the standard algorithm adopted by the Tropical Ocean-Global AtmosphereCoupled-Ocean Atmosphere Response Experiment (TOGA COARE). The comparison ismade for observations from 96 Tropical Atmosphere Ocean (TAO) array and National Oceanographic Data Center (NODC) moorings in the equatorial and North Pacific Ocean spanning years 1990–1999. The bulk formulae are shown to have very small median root–mean-square differences with respect to the TOGA COARE estimates: ≈ 0.003 N m-2, 1.0 W m-2, and 10.0 W m-2 for the wind stress, sensible heat flux, and latent heat flux, respectively.

The variability of air–sea fluxes during the 1997–1998 ENSO is also examined, along with a possible relationship between air–sea fluxes and surface ocean mixed layer depth (MLD). The wind stress and latent heat flux during the 1997 El Niño are found to be greater in the warm pool of the western Pacific than in the central Pacific where the ENSO is most clearly seen. These differences disappear upon the start of La Niña. The MLD in the equatorial Pacific is found to be moderately correlated to air–sea fluxes just before the start of the 1998 La Niña and poorly correlated otherwise.

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Kara, A.B., Rochford, P.A. & Hurlburt, H.E. Air–Sea Flux Estimates And The 1997–1998 Enso Event. Boundary-Layer Meteorology 103, 439–458 (2002). https://doi.org/10.1023/A:1014945408605

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  • DOI: https://doi.org/10.1023/A:1014945408605

  • Bulk formulae
  • El Niño
  • La Niña
  • Latent and sensible heat flux
  • Ocean mixed-layer depth
  • Wind stress