Mio TAKAHASHI
A study on catch ratio of a newly developed precipitation gauge
Toshiro KUMAKURA
It is apparent to underestimate snowfall amount with a precipitation gauge in snowfall measurement under windy condition though it is needed to obtain snowfall amount correctly to prevent snow disaster along northern part of Japan. Yokoyama et al. (2003) found the catch ratio of RT-1, RT-3 and RT-4 precipitation gauges using a DFIR (Double fence intercomparison reference). In this study, a newly developed droplet counting precipitation gauge is used to estimate the catch ratio of it. First, we observed the precipitation with the RT-4 and new gauge simultaneously. A corrected amount of the precipitation was derived from the precipitation observed with RT-4 and we compared the precipitation amount with the new gauge and the corrected one. We found that the formula of the catch ratio with the new gauge as the function of the wind speed, which was smaller than the ratio of RT-4 on both of the rain and the snow, respectively. Additionally a root mean square error to the results of the new gauge was two times larger than the results obtained by Yokoyama, which meant that it was possible to delineate between the rainfall and the snowfall incompletely, and the formula to calculate the corrected precipitation from RT-4 observation had already had the significant errors.
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