ERA and Operational analyses available from the BADC


The following data from the ECMWF Re-Analysis (ERA) and Operational datasets are archived at the BADC:

Note that uninitialised data are not available for the Operational dataset due to changes in the ECMWF model. More complete details of each of these data types are given below.

Full Resolution Analysed Data

The following data are archived at 6 hourly intervals (0000, 0600, 1200, 1800 hrs) in both the ERA and Op. datasets. These fields are archived in both initialised and uninitialised form for the ERA data. The Operational analyses from the current 3D-variational assimilation system are practically equivalent to the initialised analyses from the previous Optimum-Interpolation system used in ERA.

Note that where data is held on a Gaussian N80 grid, in the ERA dataset the grid is reduced gaussian, whereas in the Operational data the grid is a full gaussian grid.

Spectral upper-air data at T106
These fields are available on 31 model levels, or on standard pressure levels (1000, 925, 850, 775, 700, 600, 500, 400, 300, 250, 200, 150, 100, 70, 50, 30, 10 hPa). Data fields common to both are temperature, vertical velocity, relative vorticity, divergence
* Pressure-level data also includes relative humidity and geopotential.
* Model-level data also includes the single level field ln(surface pressure) and specific humidity. Spec. hum. values are stored on a Gaussian N80 grid, except for the period 3rd March 1994 - 4th April 1995 when they are stored in spectral form.

Surface data on a Gaussian N80 grid
surface temperature and wetness at soil levels 1-4, snow depth, mean sea level pressure, 10 metre u,v, 2 metre temperature and dewpoint, surface roughness, albedo, skin reservoir content, percentage of vegetation, apparent surface humidity, log. surface roughness length for heat, skin temperature.

Constants
surface geopotential (orography) plus standard deviation of orography, anisotropy of subgrid scale orography, angle of subgrid scale orography, slope of subgrid scale orography, land/sea mask.

Reduced Resolution Analysed Data

A reduced resolution dataset at 2.5° resolution will also be generated by ECMWF. Due to constraints on storage space the BADC will not archive the full range of dates, but will support a subset of these data, consisting of data every 6 hours from 1st Jan 1991. This dataset contains:

Data on standard pressure levels (see above)
geopotential, temperature, specific humidity, u- wind, v-wind, vertical velocity, relative humidity.

Surface data
temperature and soil wetness at soil levels 1-4, snow depth, mean sea level pressure, 10 metre u and v, 2 metre temperature and dewpoint, surface roughness, albedo, skin reservoir content, percentage of vegetation, apparent surface humidity, log. surface roughness length for heat, skin temperature.

Constants
surface geopotential (orography) plus standard deviation of orography, anisotropy of subgrid scale orography, angle of subgrid scale orography, slope of subgrid scale orography, land/sea mask.

Forecasts

Some fields of interest are not analysed directly but are available from the forecast model. These data are on the Gaussian N80 grid and standard pressure levels.

24 hour forecasts are made twice per day at 0000 and 1200 hrs for 1979 - present. These forecasts enable the accumulation of hydrology, energy and momentum flux fields at the surface and top of the atmosphere. The quantities are accumulated over the latter part of the forecast to avoid problems with the model in the earlier times. Units are kg/m2 for hydrology, W/m2 for energy and N/m2 for stresses.

Forecast data
large scale precipitation (including snowfall), convective precipitation (including convective snowfall), surface sensible heat flux, surface latent heat flux, total cloud cover, surface solar radiation, surface thermal radiation, top solar radiation, top thermal radiation, u-stress, v-stress, latitudinal gravity wave stress, meridional gravity wave stress.

Averaged Data

(Note: at present, none of these data have been extracted from ECMWF archives and the BADC is not in a position to confirm the accuracy of the information below).

These are all based on the 2.5° grid on pressure levels. Averages, variances and covariances will be made available by ECMWF for the analyses, 6 hour and 24 hour forecasts for the period 1979 - present. The following averages are proposed: monthly averages, zonal averages, global averages, monthly / zonal averages, global / monthly averages.