A Comparison of Sea Surface Fluxes over Southern Indian Ocean Cruise Expedition Observation and NCEP Reanalysis

Abstract

Surface layer atmospheric and ocean observations have been collected along the cruise track from a special scientific expedition to Antarctica. Bulk estimates of surface momentum flux, sensible heat flux and latent heat flux have been computed applying bulk algorithms from the data collected along cruise track during the time period January 27 to March 31, 2006, and compared the results with National Centre for Environmental Prediction (NCEP) reanalysis. Underestimation of surface momentum flux in roaring forties (40°S–50°S) area of Indian Ocean is seen from NCEP reanalysis. Systemic differences in sensible and latent heat fluxes between observed and NCEP reanalysis have been found. Along the cruise track, the average sensible (latent) heat flux was 9.45 Wm⁻² (67.46 Wm⁻²) and 3.75 Wm⁻² (64.45 Wm⁻²) from the direct measurement and NCEP reanalysis, respectively. The NCEP reanalysis is being widely used in numerical modeling studies, and the discrepancies shown in the NCEP reanalysis in present study will be of immense use to the modeling community of the Indian Ocean in general and Southern Indian Ocean in particular.

Keywords:

• Cruise
• surface layer observation
• Southern Indian Ocean
• surface layer flux

Acknowledgements

We thank the Indian National Centre for Ocean Information Service (INCOIS) in Hyderabad, National Centre for Antarctic and Ocean Research (NCAOR) in Goa and Ministry of Earth Sciences (MoES) in New Delhi for providing financial support. The authors would also like to thank NCAOR/MoES for giving Amitabh Mitra an opportunity to be a part of the expedition team to Antarctica.