An Investigation of the Consistency of TAO–TRITON Buoy-Mounted Capacitance Rain Gauges

Abstract

he common use of remotely located, buoy-mounted capacitance rain gauges in the tropical oceans for satellite rainfall verification studies provides motivation for an in situ gauge bias assessment. A comparison of the biases in rainfall catchment between Pacific island tipping-bucket rain gauges and capacitance rain gauges mounted on moored buoys in the tropical Pacific is conducted using the relationship between the fractional time in rain and monthly rainfall. This study utilizes the widespread spatial homogeneity of this relationship in the tropics to assess the rain catchment of both types of gauges at given values for the fractional time in rain. The results indicate that the capacitance gauges are not statistically significantly biased relative to the island-based tipping-bucket gauges. In addition, given the relatively small error bounds about the bias estimates any real bias differences among all the tested gauges are likely to be quite small compared to monthly rainfall totals. Underestimates resulting from wind biases, which may be substantial, are not documented in this paper.