Inter-Comparison of Numerical Model Generated Surface Winds with QuikSCAT Winds over the Indian Ocean

Abstract

The accurate surface wind in the equatorial Indian Ocean is crucial for modeling ocean circulation over this region. In this study, the surface wind analysis generated at the European Center for Medium Range Weather Forecasts (ECMWF) and the National Centers for Environmental Prediction (NCEP) are compared with NASA QuikSCAT satellite derived Level2B (swath level) and Level3 (gridded) surface winds for the year 2005. It is observed that the ECMWF winds exhibit speed bias of 1.5 m/s with respect to QuikSCAT Level3 in the southern equatorial Indian Ocean. The NCEP winds are found to exhibit speed bias (1.0–1.5 m/s) in the southern equatorial Indian Ocean specifically during January–February 2005. The biases are also observed in the analysis when compared with Level2B product as well; however, it is less in comparison to Level3 products. The amplitude of daily variations of both ECMWF and NCEP wind speed in Bay of Bengal and parts of the Arabian Sea is about 80% of that in QuikSCAT, while in the equatorial Indian Ocean it is about 60% of that of QuikSCAT.

Keywords:

• QuikSCAT
• winds
• L2B
• L3
• Indian Ocean
• ECMWF
• NCEP

Acknowledgements

The authors thank the two anonymous reviewers for their critical and insightful comments and suggestions, which were helpful in improving the content and quality of presentation of this manuscript. The authors thank the JPL PO.DAAC that makes the QuikSCAT data freely available. The authors are thankful to National Centers for Environmental Prediction (NCEP) for providing NCEP GDAS analysis data freely through the NCEP Web site. The European Center for Medium Range Weather Forecasts (ECMWF) is acknowledged for providing daily ECMWF wind analysis for the year 2005. The encouragement and help from the Director, the Deputy Director, RESA, the Group Director, MOG and Head ASD of Space Applications Centre, ISRO Ahmedabad are thankfully acknowledged.