Altimeter Near Real Time Wind and Wave Products: Random Error Estimation

Abstract

Triple collocation technique is used to estimate the errors in near-real time altimeter wind and wave products of Jason-2, Envisat and Jason-1. Significant wave height (SWH) error is estimated by collocating altimeter products with buoys and model hindcasts over the period August 1, 2009 to July 31, 2010. It is estimated that Jason-2 absolute SWH error is about 0.13 m, or about 5.4% relative to the mean SWH value. The SWH errors of Envisat, Jason-1, buoys and the stand-alone model hindcast are about 6.2%, 7.8%, 8.6% and 9.7%, respectively. The wind speed error is estimated by collocating altimeter products with buoys and ECMWF model 1-day forecast over the same period. Jason-2 wind speed absolute error is about 1.0 m.s⁻¹ (∼11.9% of the mean). For the collocation data sets used, it is found that wind speed errors of Envisat, Jason-1, the buoys and the model 1-day forecast are, respectively, 0.9 m.s⁻¹, 1.0 m.s⁻¹, 1.2 m.s⁻¹ and 1.0 m.s⁻¹.

Keywords:

• Atmospheric model
• ECMWF
• error estimation
• Envisat
• FDMAR
• OGDR
• OSDR radar altimeter
• random error
• significant wave height
• triple collocation technique
• WAM
• wave buoy
• wave model
• wind speed

Acknowledgements

This work depends mainly on altimeter and in situ data made available by various data providers around the world including but not limited to Centre National d’Etudes Spatiales (CNES), European Space Agency (ESA), European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) and National Oceanic and Atmospheric Administration (NOAA).