Sensitivity of near-surface Tropical Instability Waves to submonthly wind forcing in the tropical Atlantic

Type Article
Date 2009
Language English
Author(s) Athie Gabriela1, 2, Marin Frederic1, 3, Treguier Anne-Marie4, Bourles Bernard1, 5, Guiavarc'h Catherine4
Affiliation(s) 1 : Univ Toulouse, UPS OMP PCA, LEGOS, F-31400 Toulouse, France.
2 : IRD, LEGOS, F-29280 Plouzane, France.
3 : IRD, LEGOS, F-31400 Toulouse, France.
4 : UBO, IRD, IFREMER, CNRS,Lab Phys Oceans, F-29280 Plouzane, France.
5 : IRD, LEGOS, Cotonou, Benin.
Source Ocean Modelling (1463-5003) (Elsevier Sci Ltd), 2009 , Vol. 30 , N. 4 , P. 241-255
DOI 10.1016/j.ocemod.2009.06.016
WOS© Times Cited 15
Keyword(s) Equatorial Atlantic, Intra seasonal variability, Tropical instabilities, Ocean mixed layer, Sensitivity numerical experiments
Abstract This study demonstrates the sensitivity of the near-surface properties in the tropical Atlantic Ocean to the high-frequency of the winds in numerical simulations. At intra-seasonal timescales (2-50 days), two distinct period ranges dominate the variability in the upper ocean: periods between 2 and 20 days, which are essentially wind-forced and periods between 20 and 50 days, due mostly to Tropical Instability Waves (TIWs). Using a numerical model forced by different wind fields, it is shown that the characteristics of the intra-seasonal variability in the ocean surface mixed-layer are strongly dependent on the wind forcing. Submonthly winds are shown to force large variability in the upper ocean that can strikingly decrease the amplitude of the TIWs in the mixed-layer and their imprint on the horizontal distribution of sea surface temperatures. Wind products containing too much energy at submonthly periods thus prevent wind-forced simulations from reproducing a realistic surface signature of TIWs, when compared to satellite observations of sea surface temperature. In addition, submonthly wind variability may be responsible for part of the observed interannual variability of the TIW signature in the temperature. The impact of submonthly winds is strongest in the mixed-layer: beneath the mixed-layer, all simulations show similar characteristics of the TIWs. (C) 2009 Elsevier Ltd. All rights reserved.
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