Ku-band backscatter responses to frontal sea surface temperature (SST) chan
ges are studied and applications of a high-resolution scatterometer to remo
te sensing of an SST front are suggested. Ocean backscatter signatures were
measured with an airborne Ku-band scatterometer across the Gulf Stream SST
front during the Surface Wave Dynamics Experiment. Oceanic and atmospheric
parameters were measured bg buoys, bg the Scanning Radar Altimeter, and by
the Advanced Very High Resolution Radiometer, and the surface current fiel
ds analyzed by the Fleet Numerical Meteorology and Oceanography Center were
obtained, Vertical polarization backscatter difference across the SST fron
t with an SST difference of 9 degrees C is more than 5 dB in several flight
lines. Large horizontal polarization backscatter changes are also observed
across the SST front with an SST difference approximately one-half of that
in the vertical polarization backscatter case. Corresponding wind speed di
fferences cannot account for the large backscatter changes in view of Seasa
t-A Satellite Scatterometer (SASS) geophysical model functions depending on
ly on neutral wind velocity, For both polarizations, upwind backscatter on
the cold side is smaller than or close to crosswind backscatter on the warm
side for incidence angles larger than 20 degrees and smaller than 60 degre
es. This suggests that the SST front can be detected with backscatter measu
red bg a spaceborne radar at a fixed azimuth angle even if wind directions
are different over the cold and warm sides.