Validation and Intercomparison of SARAL/AltiKa and PISTACH-Derived Coastal Wave Heights Using In-Situ Measurements

SARAL/AltiKa, the first Ka-band altimeter, now provides an opportunity to study wave characteristics in the world's coastal ocean with improved accuracy. In the present work, AltiKa-derived significant wave heights (Hs) in the coastal ocean and inland water bodies have been analyzed using in-situ measurements. Analysis shows that AltiKa measured Hs agree well with the in-situ measurements with high correlation (0.98), low bias (6 cm), and low RMSE (19 cm) in the coastal ocean, and the performance is highly consistent across different coastal zones in the three tropical oceans. AltiKa performance is found to be very good (RMSE = 24 cm and correlation = 0.94) near to the coast (<2 km). In addition to the evaluation of AltiKa Hs, another coastal altimetry product, Innovative Processing System Prototype for Coastal and Hydrology Applications (PISTACH)-derived Hs using Jason-2 altimeter, has also been validated with in-situ measurements. The OCE3 retracking algorithm provided in PISTACH is able to improve the Jason-2 Hs in the 100-25 km coastal zone. None of the retracking algorithms showed significant improvement of Hs in the 0-10 km coastal zone.