Observations of the Effect of Rain Temperature on the Surface Heat Flux in the Intertropical Convergence Zone

Abstract

The thermohaline response of the ocean to a short (10 h) but intense (95 mm) nighttime rainfall event was observed during a transit through the ITCZ. Two CTD profiles and shipboard measurements of air?sea fluxes were consistent with the assumption that rain temperature equals the wet-bulb temperature, within measurement errors. Although the net freshwater input and the net heat loss inferred from the T?S characteristics of the surface layer were ?30% smaller than those obtained by integrating the measured air?sea fluxes, owing to different spatial sampling, inherent limitations of rain measurement from ship, and contamination by internal waves, the two independent estimates of the net heat deficit agreed remarkably well, within 2.4%, when expressed per unit mass of rain (?72kj kg?1). The heat flux due to the temperature of the rain accounted for about 40% of the net heat flux during rain, and therefore cannot be neglected.