ECMWF reanalysis output for the ISLSCP-I project

The ECMWF, and ECMWF, NASA/LaRC data on the ISLSCP Initiative I CD-ROM are comprised of the ECMWF/TOGA Advanced Operational Analysis Data the ECMWF/TOGA Supplementary Fields data and a hybrid dataset using the radiation fields within the ECMWF/TOGA Supplementary Fields and the NASA/LaRC Surface Shortwave and Longwave Radiation Fluxes data set.

ECMWF/TOGA Advanced Operational Analysis Data Sets:

This dataset contains uninitialized analysis values at the resolution of the data assimilation system in operational use at ECMWF. The Advanced Operational Analysis Data Set, on the ISLSCP Initiative 1 CD-ROM, are comprised only of the Surface and Diagnostic Fields.

The original ECMWF Surface and Diagnostic Fields data set was represented on a 320 x 160 grid, with a regular spacing of 1.125 degrees (lat/long) between points along each row for the period January 1, 1987 - December 31, 1988. Grid point values were stored in latitude rows starting at the north and working southwards; within each row values ran from west to east, starting at the 0 degree longitude. All of the ECMWF Surface and Diagnostic Fields Data sets, on the ISLSCP CD-ROM, have been converted, by the Goddard DAAC, to a 1 X 1 degree equal angle lat/long grid, starting at 90 degrees latitude North and 180 degrees longitude West (see section 9.3.1).

The Parameters from the Surface and Diagnostic Fields data set, on the ISLSCP Initiative I CD-ROM set, are:

Surface Fields - surface pressure, surface temperature, soil moisture, snow depth, mean sea level pressure, u- and v-components of wind at 10m, temperature at 2m, dew point temperature at 2m, deep-soil wetness, deep-soil temperature.

Diagnostic Fields - surface roughness, albedo, climate deep-soil wetness, climate deep-soil temperature.

ECMWF/TOGA Supplementary Fields Data Set:

The Supplementary Fields Data Set contains surface heat fluxes, net radiation and u- v-stress derived from 6-hour forecasts used as "first-guess" for analyses within ECMWF's data assimilation system. The Supplementary Fields Data Set acquired from ECMWF were represented in the same format, as the Surface and Diagnostic Fields Data set, described above. All ECMWF Supplementary Fields Data Sets, on the ISLSCP CD-ROM, have been converted, by the Goddard DAAC, to a 1 X 1 degree equal angle lat/long grid, starting at 90 degrees latitude North and 180 degrees longitude West (see section 9.3.1).

The Parameters from the Supplementary Fields data set, on the ISLSCP Initiative I CD-ROM set, are: surface flux of sensible heat, surface flux of latent heat, surface shortwave radiation, surface longwave radiation, top of the atmosphere shortwave radiation, top of the atmosphere longwave radiation, and the zonal and meridional components of the surface wind stress.

Most of the near-surface meteorological data are taken directly from forecast products generated by the ECMWF operational numerical weather prediction model.

ECMWF requested that the following information be provided to users of the ECMWF data:

The ECMWF data sets are adapted to a specific model orography; the data sets have biases which are only partially documented (reference list).

No surface observations of T, q, precipitation, nor surface wind observations over land were used in the analysis.

Model spin up can seriously affect the flux data. All flux fields, including total cloud cover, are first-guess fields (i.e. 6 hour forecasts).

All the time-evolving fields on this CD-ROM, such as soil moisture, snow depth and deep soil parameters include no direct observations, but evolve during the data assimilation cycle.

The Technical Attachment to the Description of the ECMWF/WCRP Archive should be cited by users in publications (see reference section).

In addition to the routine products extracted from the ECMWF archive for this data set, NASA/GSFC generated synthetic 'hybrid' 6-hourly incident surface shortwave and longwave radiation fluxes, and NOAA/NMC generated 'hybrid' 6-hourly total and convective precipitation rates. As presented on the CD-ROMs the data sets include:

I. Prescribed/Diagnostic Fields (see table in section 1.3),
II. Monthly (6-hourly) Forcing Fields (see table in section 1.3),
III. Diurnally-resolved (6-hourly) Forcing Fields (see table in section 1.3). (These include the hybrid products).

The data in I are intended for reference rather than direct use by modelers. The data sets in II are suitable for forcing long time-step models. The data sets in III have been put together for the express purpose of forcing energy-water-carbon land models.

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