Moored Observations of Precipitation Temperature

Abstract

Direct observations of precipitation temperature were made from a surface buoy deployed for four months in the western Pacific warm pool. The observed rain droplet temperatures are equal to the wet-bulb temperature to within the measured wet-bulb temperature uncertainty of ±0.4°C. The rain droplet temperatures are 4.8°?5.8°C cooler than the ocean surface temperature. The sensible heat flux associated with the rain is found to be a significant component for the net surface heat while it is raining, ranging from ?65.0 to ?204 W m?2 (ocean cooling) and accounting for 15%?60% of the net heat flux for any single rain event. The rain heat flux is also important on longer timescales in the warm pool, where there is a close balance between surface heating and cooling and high precipitation rates. During the 4-month deployment period, the rain heat flux is 2.8 W m?2 (ocean cooling) and 15% of the net surface heat flux.