LIU Zhengwen1,2 YANG Yanming2 WEN Hoongtao2 NIU Fuqiang2 XU Xiaomei1

(1　　College of Oceanography and Environmental Science, Xiamen University Xiamen 361005)

(2　  Third Institute of Oceanography, SOA Xiamen 361005)

Received Aug 20, 2009

Revised Oct. 19, 2009

Abstract  A method combined with the nonlinear least-square regression to quantitatively estimate rainfull rate over water surface from the different spectrum shapes generated by rainfall in some frequency bands was presented. About 2000 min spectrum data generated by rainfull have been collected in an open-lake in Xiamen city. As a result, the spectrum shape in 15-30 kHz is fitted to log-linear law which allows classification of rain into three categories from the spectrum slop: no rain, drizzle(rainfall rate <10mm/h)and heavy rain (rainfall rate >10mm/h). Then, rainfall detection is made and rainfall rate is quantified in drizzle time with Logistic model in the frequency bands of 2-15kHz, and the rainfall rate in heavy rainfall also quantified with log-linear regression. Finally, all measured spectrum data are used to calculate rainfall rate with the algorithm. The results show that the estimated rainfall rates are comparably coincident with the synchronously measured ones. The averate error of accumulative rainfall per min is only 1%-4%.

PACS numbers:43.30