Relationship between Nature of ASAR Image and Marine Variable Profiles over Ocean Fronts

GAO Yuan; SUN Jian

Abstract：In this study,we combined the wave mode data from Advanced Synthetic Aperture Radar (ASAR) boarded on ENVISAT satellite and AVHRR sea surface temperature (SST)and NCDC sea surface wind (SSW) data.The datasetsincluding normalized backscattering cross section (σ0),SST and SSW were established on the thermal fronts we screened.After gathering statistics of the variable profiles,we carried out qualitative analysis on the influence of SST and SSW on σ0.The results showed that about 60％ of the front samples had a higher σ0 in the side of higher SST and about 70％ of the front samples had a higher in the side of higher SSW.In this study,we only analyzed the front samples whose SST and SSW situations conformed to the ideal state (higher SST corresponding higher,and SSW is the same).We found that marine variable profiles differenceinfiuencedSAR image,and great temperature (ΔSST) and wind speed (ΔSSW) differences always corresponded with great σ0 differences (Δσ0) in image.The mean level of marine variable profiles also influenced Δσ0,a higher mean sea surface temperature (SST)in the front will cause a higher Δσ0,but a higher mean wind speed (SSW)will lead to a lower Δσ0.We used the power law exponent which defines to calculating the wind speed coefficient (B) data of our samples with Δσ0 and wind speeds in two sides of a front.The result which was given by polynomial fitting method showed that B andthe marine variable profiles coefficient we assumed hada goodcorrelation.We can infer that SST influences in an ideal state by and ΔSSW which is causedby ΔSST,and sample statistics are accorded with the power law exponent.Our results provided abasis for ocean front profiles inversion with SAR data.