RAINFALL OBSERVATION IN THE COASTAL AREA WITH OPTICAL DISDROMETERS IN THE SUMMER OF 2013

Abstract

 Rainfall observation has been widely performed with ground rain gauges and radars. Radar can obtain spacial distribution of rainfall. As the drop size distribution is assumed, rainfall intensity is estimated using the Z-R relationship and the K_DP-R relationship. However, drop size distribution varies depending on rainfall type and area. In this study, two optical disdrometers are installed at two different heights on an Observational Tower of the Kyoto University Disaster Prevention Research Institute at Wakayama prefecture to have a rainfall observation on the sea in the summer of 2013. The number of droplets with a diameter less than 1mm obtained a feature that increases with the wind speed. This is considered to be sea spray generated from the sea surface. In this case, it is suggested in the observation of rainfall on the sea that the variation of drop size distribution fluctuates according to the wind speed. Furthermore, it is necessary to consider the mixture of droplets.