Heavy rain effects on scatterometer returns from rain roughened seas

The authors conducted experiments at the Rain-Sea Interaction Facility at Wallops Island to investigate the relationship between scatterometer returns and rain intensity. These data were obtained with 2.8 mm diameter drops that impact a water surface at terminal velocity. The conditions ranged from 5 to 200 mm hr^-1 rain rate (R). Scatterometer returns (NRC) were obtained from a 13.5 GHz scat with vertical polarization and at 30 degrees incidence angle. For this broad range of rain rates, the data show a departure from the linear relationship that was developed for light rains (<30 mm hr^-1 ) by Bliven et al. (1993). For this extended range of rainfall rates, the relationship between NCR and R is much better modeled by a square-root dependence