Wind Speed dependence of Air-Sea Exchange parameters over the Indian Ocean during INDOEX, IFP-99

Abstract. Air-Sea exchange of momentum, heat and moisture over the oceanic surface plays an important role in understanding several processes spanning various scales of atmospheric and oceanic motions. The present study provides estimates of air-sea exchange parameters along the cruise track of the Intensive Field Phase of Indian Ocean Experiment (INDOEX, IFP-99) conducted on board Oceanic Research Vessel (ORV) Sagar Kanya during 20 January–12 March 1999 for a large region of the Indian Ocean. The study is aimed at acquiring a better understanding of the wind speed dependence of air-sea interaction parameters, such as roughness lengths for wind (z₀), temperature (z_0t) and hu-midity (z_0q), which play a key role in the determination of the air-sea exchange coefficients and interface fluxes across the tropical oceans. The variation of drag coefficient (C_D), sensible heat and water vapor exchange coefficients (C_H and C_E), are also discussed in relation to the wind speed. An empirical relation is derived between the estimated values of drag coefficients and the observed values of wind speeds for the hitherto data-sparse regions over the tropical Indian Ocean.

Key words. Oceanography: physical (air-sea interaction) Meteorology and atmospheric dynamics (ocean-atmosphere interaction) – Oceanography: physical (marine meteorology)