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

Email: apolonsky5@mail.ru

DOI: 10.33075/2220-5861-2020-3-30-38

UDC 551.46.062

Abstract:

   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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