ECMWF Ocean Analysis System

A new operational ocean analysis/reanalysis system (ORA-S3) has been implemented at ECMWF. The reanalysis started from 01/01/1959: it is continuosly maintained up to 11 days behind real time and is used to initialize seasonal forecasts as well as to provide a historical representation of the ocean for climate studies. It has several innovative features, including an on-line bias-correction algorithm, the assimilation of salinity data on temperature surfaces and assimilation of altimeter-derived sea level anomalies and global sea level trends. It is designed to reduce spurious climate variability in the resulting ocean reanalysis due to the non-stationary nature of the observing system, while still taking advantage of the observation information. In addition to the basic analysis, a real-time analysis is produced (RT-S3). This is needed for monthly forecasts and in future may be needed for shorter-range forecasts. It is initialised from the near-real-time ORA-S3 and run each day from it. The new analysis system is compared with the previous operational version; the equatorial temperature biases are reduced and equatorial currents are improved. The impact of assimilation in the ocean state is discussed by diagnosis of the assimilation increment and bias correction terms. The resulting analysis not only improves the fit to the data, but also improves the respresentation of the interannual variability.

We have two grids, this one (1x1) and the original hope grid (raw). The APDRC only has the monthly fields through 2009.

Balmaseda, M. A., Vidard, A., and Anderson, 2008: The ECMWF Ocean Analysis System: ORA-S3, Mon. Weather Rev., 136, 3018-3034.

potential temperature (degC), salinity, ocean velocity (m/s), sea level (m), mixed layer depth (m), depth of 20-degree isotherm (m), ave temperature in upper 300m (degC), vertically integrated heat transport (J/m/s), wind stress (Pa), net surface heat flux (W/m2)
ZonalGlobal by 1 deg
MeridionalGlobal by 1 deg
Vertical 5 15 25 35 46.25 60 75 90 105 120 135 150 165 180 195 211.25 230 255 290 335 415 535 720 1020 1450 2100 3000 4000 5250
TemporalJan 1959 to Dec 2009 by 1 month(s)
Volume40MB per month
SourceECMWF's  Ocean Analysis
AcquiredMar 19, 2008 (Updated 3/2010)
APDRC contact