CoAuthors

Hui Feng (Univ. of New Hampshire, United States); Ngan Tran (CLS, France); Bertrand Chapron (IFREMER, France)

This study involves computation and analysis of 2D and 3D sea state impacted altimeter range bias (SSB) models for the Ka-band (AltiKa) and Ku-band (Jason-3) radar. These models are derived using the so-called direct method based on altimeter sea level anomaly (SLA) data, sea state estimates, and their relation determined nonparametric spline smoothing estimator. Specific objectives are 1) to use the near-final quality AltiKa data to newly evaluate on-orbit Ka-band SSB signatures (magnitude and variability) in multiple dimensional space, 2) to compare on-orbit AltiKa SSB to past field-observed electromagnetic (EM) radar bias observations and theoretical EM bias predictions, 3) to document similarities and differences for the satellite-derived SSB features at Ka-band vs. Ku-band, and 4) and offer interpretation of the observed differences between on-orbit Ka-band and Ku- band SSB models in terms of long-wave tilt, long-wave short-wave hydrodynamic interactions, and wind stress impacts from this combination of observations and theory. Data indicate that the Ka-band SSB has a reduced wind speed dependence compared to Ku-band. To first-order, this accords with an overall attenuation of the underlying sea state nonlinearities due to the increase of short wind-wave impacts. Overall implications for future Ka-band missions such as SWOT will be discussed.