Evaluation of OSCAR ocean surface current product in the tropical Indian Ocean using in situ data

• Published in: Journal of Earth System Science Vol. 122; no. 1; pp. 187 - 199
• Main Authors: SIKHAKOLLI, RAJESH, SHARMA, RASHMI, BASU, SUJIT, GOHIL, B S, SARKAR, ABHIJIT, PRASAD, K V S R
• Format: Journal Article
• Language: English
• Published: India Springer-Verlag 01.02.2013; Springer Nature B.V
• Subjects: Buoy measurements; Buoys; Climatology; correlation; Dipoles; Drifters; Earth and Environmental Science; Earth Sciences; earth system science; Fourier analysis; Kinetic energy; Marine; Moored buoys; Ocean circulation; Ocean currents; Ocean surface; Oceans; Periodicities; Physical oceanography; Remote sensing; Satellite observation; satellites; Space Exploration and Astronautics; Space Sciences (including Extraterrestrial Physics; tropics; Water circulation; water currents; Indian Ocean; ISW, East Indian Ocean, Wyrtki Jet; ISW, Indian Ocean; ISW, Tropical Indian Ocean; remote sensing; drifter data; Indian Ocean circulation; Ocean surface current; buoy currents
• ISSN: 0253-4126; 0973-774X
• DOI: 10.1007/s12040-012-0258-7

The OSCAR (ocean surface current analysis real-time), which is a product derived from various satellite observations, has been evaluated in the tropical Indian Ocean (TIO) in two different ways. First, the OSCAR-derived monthly climatology has been compared with available drifter-derived climatology in the TIO. From the comparison of the two climatologies, one can infer that OSCAR product is able to capture the variabilities of the well-known surface current systems in the TIO reasonably well. Fourier analysis of the major current systems, as reproduced by OSCAR, shows that the dominant annual and semiannual periodicities, known to exist in these systems, have been faithfully picked up by OSCAR. Next, the evaluation has been carried out by comparing the OSCAR currents with currents measured by moored buoys. The zonal component of OSCAR-current is in good agreement with corresponding component of buoy-observed current with a correlation exceeding 0.7, while the match between the meridional components is poorer. The locations of the peaks of the mean and eddy kinetic energies are matching in both the climatologies, although the peak in the drifter climatology is stronger than the same in the OSCAR product. Finally, an important feature of Indian Ocean circulation, namely the reverse Wyrtki jet, occurring during anomalous dipole years, has been well-reproduced by OSCAR currents.