Journal of Oceanography, Vol. 59 (No. 2), pp. 235-244, 2003
Dongliang Zhao1,2* and Yoshiaki Toba1,3
1Earth Observation Research Center, National Space Development Agency of Japan, Tokyo 104-6023, Japan
2Physical Oceanography Laboratory, Ocean University of China, Qingdao 266003, China
3Research Institute for Environmental Sciences and Public Health of Iwate Prefecture, Morioka 020-0852, Japan
(Received 8 January 2002; in revised form 7 October 2002; accepted 10 October 2002)
Abstract: We propose a new analytical algorithm for the estimation of wind speeds from altimeter data using the mean square slope of the ocean surface, which is obtained by integration of a widely accepted wind-wave spectrum including the gravity-capillary wave range. It indicates that the normalized radar cross section depends not only on the wind speed but also on the wave age. The wave state effect on the altimeter radar return becomes remarkable with increasing wind speed and cannot be neglected at high wind speeds. A relationship between wave age and nondimensional wave height based on buoy observational data is applied to compute the wave age using the significant wave height of ocean waves, which could be simultaneously obtained from altimeter data. Comparison with actual data shows that this new algorithm produces more reliable wind speeds than do empirical algorithms.