Sea-spike backscatter from a steepening wave

H-pol and V-pol backscatter cross sections at incidence angles of 85/spl deg/, 60/spl deg/, and 40/spl deg/ are computed at X-band for two temporal sequences of simulated sea waves, one with a wavelength of 1 m and the other with a 2.3 m wavelength, that are steepening as they undergo breaking. At an incidence angle of 85/spl deg/ (5/spl deg/ grazing) H-pol and V-pol backscatter from these waves are shown to have the characteristics of a sea spike. At a 60/spl deg/ incidence angle only the l m sequence produces a sea spike. No sea spike is seen from either sequence at 40.