Evaluation of ENVISAT ASAR data for measurement of surface wind field over the Korean east coast

The detailed knowledge of ocean surface wind field is useful for understanding of ocean circulation and variability in a specific spatial and temporal window. An efficient way to obtain such information in sufficient density is through satellite remote sensing. The most recent environmental observation satellite, ENVISAT, has an Advanced Synthetic Aperture Radar (ASAR), which operates at C-band frequency. The ASAR has the potential of retrieving sea surface wind field more accurately than the ERS-1/2 AMI because the ASAR can collect high resolution images with a various viewing geometry and simultaneously in two polarization mode. Several ASAR images including alternating polarization mode and wide swath mode were obtained off the eastern coast of Korean peninsula during the winter season. Simultaneously, we installed two corner reflectors on the near beach to calibrate ENVISAR ASAR data. In this paper we combined polarization ratio models and modified C-band VV-polarization wind speed retrieval models (CMOD_4 and CMOD_IFR2) to apply them to ASAR alternating polarization mode data. We compared the resulting wind fields estimated from ENVISAT ASAR data with wind speed and direction measured by the several coastal automatic weather systems and two ocean buoys which are deployed at 10 km and 100 km off the east coast of Korean peninsula respectively.