Generation and validation of analysed wind vectors over the global oceans

Abstract

Daily and 12 hourly gridded analysed wind vectors (AWVs) over global ocean were generated using the simple spatial interpolation scheme of ‘box averaging’, with a horizontal resolution of 0.5° × 0.5°. For daily analysed winds, observations only from Oceansat-2 Scatterometer (OSCAT) were used. The 12 hourly AWVs were generated by combining the data from both OSCAT and Advanced Scatterometer (ASCAT). Apart from ocean wind vectors, an effort was made also to produce analysed wind stress, divergence and curl of wind stress. The daily and 12 hourly analysed winds were validated using in situ observations from 97 global moored buoys and data from European Centre for Medium Range Weather Forecasting analyses for a period of 9 months. The validation result shows a good agreement between AWV products and the buoy and model analysis data, yielding a standard deviation of around 2 m s⁻¹ in wind speed and around 20° in wind direction.

Acknowledgements

The authors sincerely express their gratitude to the EUMETCAST for providing ASCAT wind data. The authors are also thankful to NDBC, TAO, PIRATA and RAMA for providing buoy observations and ECMWF for providing 6 hourly analysis data used for validation. They are very much grateful to Dr Ad Stoffelen, the Royal Netherlands Meteorological Institute (KNMI), and Prof. R. Ramesh, Physical Research Laboratory (PRL), for their positive opinion on the work. Finally, the authors are grateful to Director, Space Applications Centre for his encouragement in the present work. The authors thank two anonymous reviewers, editor and administrator of the journal for very constructive comments on an earlier version of this article.