title: Vicarious calibration of the third and fourth Stokes parameters of Windsat measurements.
abstract: Microwave observations made at the third and fourth Stokes parameters can be used to determine the surface wind direction over oceans. However, due to their smaller amplitudes (less than 3 K at the third Stokes parameter and 1 K at the fourth Stokes parameter), the absolute calibration to these measurements becomes crucial. A new methodology is developed in this study to calibrate the Windsat third and fourth Stokes parameters through tropical rain forest measurements over the Amazon and central Africa. It is found that the Windsat fourth Stokes parameter at 18 GHz has biases of the order of 0.5 K, which could severely affect the wind vector retrievals.
authors.affiliation: QSS Group Incorporated, Joint Center for Satellite Data Assimilation, 5200 Auth Road E/RA2, Room 7042, Camp Springs, Maryland 20746, USA.
authors.forename: Quanhua
authors.initials: Q
authors.lastname: Liu
authors.forename: Fuzhong
authors.initials: F
authors.lastname: Weng