Verification of reanalysis data for the tropical zone of the Indian Ocean. Part 1. Multi-year hydrophysical averages

A.B. Polonsky, A.V. Torbinskii, A.V. Gubarev

Institute of Natural and Technical Systems, Russian Federation, Sevastopol, Lenin St., 28


DOI: 10.33075/2220-5861-2020-3-30-38

UDC 551.46.062


   The results of operational reanalyses for the studying the processes in the “ocean-atmosphere” system are becoming more and more widespread. This information can be used to solve both fundamental and applied problems. Such data can differ significantly from the results of direct instrumental measurements.

   In this regard, joint analysis of real observational data and those of various reanalysis products is very important for verifying the latter. In the Indo-Ocean region, where the number of high-quality oceanographic observations is small, this problem is especially urgent.

   The aim of the study is to evaluate the performance of ORAS5/SODA3/GLORYS reanalyses using the RAMA in the Indian Ocean. To do this, the reanalysis data are compared with the measurements made on moored buoys.

   The work used ORAS5/SODA3/GLORYS/RAMA data on the vertical distribution of potential temperature, salinity and zonal component of the current velocity at points with coordinates 55°E 12°S, 67°E 12°S and 93°E 12°S for the period 2007–2018. These data were used to compare the long-term average hydrophysical characteristics calculated from the reanalysis data and direct observational data obtained on buoys for each month.

   It is shown that the ORAS5, GLORYS, and SODA3 reanalyses reproduce the data on potential temperature and salinity on RAMA buoys at 12°S equally well. The average values of the velocities of zonal currents in all three reanalyses are lower than the observed values by 2 to 31%. In general, ORAS5 is best of all other reanalyses made.

Keywords: RAMA, SODA3, ORAS5, GLORYS, critical layer, Indian Ocean dipole.

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  1. Yamagata T., Behera S.K., Rao S A. et al. Comments on “Dipoles, Temperature Gradient, and Tropical Climate Anomalies” // Bull. Amer. Met. Soc. 2003. № 84 (10). P.1418–1422. DOI: 10.1175/BAMS-84-10-1418
  2. A.B. Polonsky, A.V. Torbinskii. Role of zonal currents velocities and planetary waves in distribution of thermal anomalies for the equatorial-tropical area of the southern Indian Ocean // Physical oceanography. 2012. № 6. P. 35–44.
  3. A.B. Polonsky, A.V. Torbinskii, A.V. Gubarev. Identification of formation mechanisms of Indian Ocean dipole // Monitoring systems of environment. 2020. № 2 (40). P. 13–18. DOI: 10.33075/2220-5861-2020-2-13-18
  4. A.B. Polonsky, A.V. Torbinskii. Critical layer in equatorial-tropical zone and Indian Ocean dipole // Monitoring systems of environment. 2019. № 2 (36). P. 88–92. DOI: 10.33075/2220-5861-2019-2-88-92
  5. Guo F., Liu Q., Sun S., Yang, J. Three Types of Indian Ocean Dipoles // J. Climate. 2015. Vol. 28 (8). P. 3073–3092. DOI: 10.1175/JCLI-D-14-00507.1
  6. (application date: 10.05.2020).
  7. (application date: 12.05.2020).
  8. (application date: 14.05.2020).
  9. (application date: 10.05.2020).
  10. Schott F.A., McCreary J.P. The Monsoon Circulation of the Indian Ocean // Progress in Oceanography. 2001. Vol. 51 (1). P. 1–123. DOI: 10.1016/S0079-6611(01)00083-0
  11. Shenoi S.S.C., Saji P.K. Near-surface circulation and kinetic energy in the tropical Indian Ocean derived from Lagrangian drifters // Journal of Marine Research. 1999. № 57. P. 885–907. DOI: 10.1357/002224099321514088
  12. Cutler A.N., Swallow J.C. Surface currents of the Indian Ocean. (To 25°S, 100°E). I. O. S. // Technical Rept. 1984, 187.
  13. Pandey V.K., Singh S.K. Comparison of ECCO2 and NCEP reanalysis using TRITON and RAMA data at the Indian Ocean Mooring Buoy point // Open access e-Journal Earth Science India. 2010. Vol. 3 (IV). P. 226–241. eISSN: 0974 – 8350
  14. Wang J., Mao K., Chen X. Assessment of several ocean reanalyzes about North 2 Equatorial Current at 160°E // Mar. Sci. Eng. 2020. 8. P. 1–7. DOI: 10.1080/1755876X.2020.1737345