The OMIP-Forcing based on ERA-15
The OMIP-forcing has been derived from the Re-Analysis (ERA) of the European Centre for Medium-Range Weather Forecasts (ECMWF). A mean annual cycle has been produced from all 15 years of the ERA with typical daily fluctuations superimposed by using Gaussian filtering. The precipitation and evaporation over the continents have been transformed into runoff by using a scheme, which is based on the catchment areas, the annual runoff observations of the 35 largest rivers, and the main drainage basins. The scheme is run independently of the ocean models. Frank Röske (MPI)
The budgets of the heat and the fresh water fluxes have been closed by modifying the bulk formulae. All three forecast cycles of the ERA have been examined with respect to the demands for the closure procedure. The 24 hour cycle has the best properties. Therefore, this cycle has been chosen to be the base of the OMIP-forcing. For all forcing parameters including the river runoff, the mean annual cycle is not available any more.
An Atlas of the OMIP-Forcing
From the forcing data an atlas of heat, fresh water, buoyancy, turbulent kinetic energy, and wind stress has been derived. Monthly means and standard deviations have been calculated and are available as ASCII data and as pictures (compressed). Zonal averages of the annual mean are shown for the heat and fresh water flux components for the global ocean and for each basin separately (Atlantic, Pacific and Indian Ocean).
The OMIP climatology is compared with six other climatologies: the direct outputs of the ERA, the Re-Analysis of the NCEP/NCAR, the COADS data in three different versions (Oberhuber 1988, da Silva 1994, Southampton Oceanographic Centre 1997), and the output of the atmospheric model ECHAM4 of the MPI.
For the intercomparison implied northward meridional heat and fresh water transports have been calculated for the global ocean and the three basins. Zonal averages are shown for each month and for the annual mean. Oceanic averages (three-monthly means and annual means) are represented as bar charts for each basin and for the Arctic Ocean separately. Flux maxima of the main heat gain and loss regions are shown for the Atlantic and Pacific.
The forcing, the atlas, and the intercomparison are described in the forcing-report.
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