Sea-surface NRCS observations in high winds at low incidence angles

We report on airborne measurements of the sea-surface normalized radar cross-section (NRCS) at incidence angles of approximately 22° obtained at both C-band and Ku-band in high-wind (> 25ms^-1) conditions. Measurements obtained over numerous research flights through tropical cyclones and high-latitude winter storms between 2011 and 2014 are composited to yield geophysical model functions in rain-free conditions. The present observations extend the results of [1], who reported high-wind NRCS for incidence angles from 30° to 50°, to a smaller incidence angle. Saturation of the mean NRCS is observed at both frequencies. In some cases the NRCS is observed to decrease with increasing wind speed beyond the saturation. The results have implications for planned and future scatterometers aiming to increase the observed swath width by extending the range of incidence angles.