Ocean Wave Period from Satellite Altimeters: Validation for Envisat Ra2

A model for ocean wave period from satellite altimeter data proposed by Gommenginger et al (2003; [1]) was applied to a dataset of ENVISAT RA2 measurements collocated with moored buoy data for cycle 15 to 26. Although the ocean wave period model was developed for Topex data gathered between 1993 and 1998, we find that the model performs equally well for RA2 Kuband without any need for adjustments to the model. This suggests that the backscatter coefficient for Topex and RA2 are well aligned and that the two altimeters return similar distributions. The model was applied also to RA2 S band data, and shows similar results as for Ku-band but with a small bias. Residual dependences of the retrieved wave period on wind speed and long wave slope suggest ways to improve the empirical altimeter wave period model if cases of low wind with swell can be identified and removed. 1. A SIMPLE EMPIRICAL MODEL FOR ALTIMETER WAVE PERIOD A new algorithm was recently proposed [1] to estimate ocean wave period from satellite altimeter measurements. Based on heuristic reasoning, a simple relationship was postulated between altimeter backscatter coefficient (σ) and significant wave height (SWH) measurements, and wave period, T: