IMPROVEMENT OF THE METHOD TO DERIVE RAIN RATES FROM RAIN GAUGE OBSERVATIONS: A VALIDATION STUDY USING A DISDROMETER

Abstract

 Usually, in deriving rain rates from rain gauge observations, observed rain amount is divided by the observation time duration (called simple method). In the case of tipping bucket, the simple method has poor performance for shorter time duration. The authors developed a new method called interpolation method, where the time of tipping is estimated in statistical manner, accumurated rain amount is interpolated in time and the rain rate is derived. In this study, using a disdrometer, rain gauge observation data is simulated. Then, the simple method and interpolation method are applied to the simulation data, and the accuracy is evaulated. It is shown that the interpolation method is more accurate than the simple method particularly for shorter time duration. In the interpolation method, the accuracy becomes higher with shorter rain gauge recording period. The method to derive 1-hour rain rate from hourly rain gauge observations has been improved further by modifying the method to estimate the time of tipping.