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Operational Surface First
Guess Data Set
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This part includes a brief description and the order forms of this specific Data Set.
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Description :
- period supported - 1 January 1985 to current date;
- each parameter is stored as a field of grid point values, in latitude rows starting at the north and working southwards; within each row values run from west to east starting at the 0° meridian;
- data are stored in FM 92 GRIB using sufficient bits to ensure that the values represented can be retrieved to an accuracy consistent with the analysis method used;
The changes to this data set are as follows:
| 1 January 1985 | Internal data is represented on a N48
Gaussian grid (48 lines of latitude, located according to a Gaussian distribution
between the pole and the equator for each hemisphere, with a regular spacing of
1.875° between points along each latitude row) Data is short term forecasts from times 0000, 0600, 1200 and 1800 UTC Forecast step available is 006 hours Fields available are surface pressure, snow depth, large scale precipitation, convective precipitation, snowfall, boundary layer dissipation, surface sensible heat flux, surface latent heat flux, MSL pressure, total cloud cover, u- and v-components of wind at 10m, 2 metre temperature, 2 metre dewpoint temperature, surface solar radiation, surface thermal radiation, top solar radiation, top thermal radiation, east-west surface stress, north-south surface stress, evaporation, surface temperature, deep soil temperature, surface soil wetness, deep soil wetness |
| 1 May 1985 | Internal data is represented on a N80 Gaussian grid (80 lines, with 1.125° between points along each row) |
| 15 July 1986 | Fields added are low cloud cover, medium cloud cover, high cloud cover, latitudional gravity wave stress, meridional gravity wave stress, gravity wave dissipation |
| 7 April 1987 | Fields added are skin reservoir content, maximum temperature at 2m since previous post processing, minimum temperature at 2m since previous post processing |
| 12 February 1991 | Step 003 added to forecast steps |
| 17 September 1991 | Internal data is represented on a N160 Quasi-regular Gaussian grid (160 lines with varying numbers of points along each row) Field added is runoff |
| 4 August 1993 | Field added is skin temperature Surface temperature, deep soil temperature replaced by soil temperature levels 1, 2, 3 and 4 Surface soil wetness, deep soil wetness replaced by soil wetness levels 1, 2, 3 and 4 |
| 1 March 1994 | Fields added are forecast albedo, forecast surface roughness, forecast log surface roughness for heat |
| 23 August 1994 | Field added is total column water vapour |
| 4 April 1995 | Field added is total column water |
| 14 May 1997 | Fields added are surface solar radiation downward, surface thermal radiation downward |
| 29 June 1998 | Field added is surface stress/Charnock |
| 27 June 2000 | Fields added are sea ice cover, snow albedo, snow density, sea surface temperature, evaporation of snow, snow melt, wind gust at 10 metres, large scale precipitation fraction, geopotential, boundary layer height, land sea mask, sunshine duration, top net solar radiation clear sky, top upward thermal radiation clear sky, surface net solar radiation clear sky, surface net thermal radiation clear sky, temperature of snow layer, ice surface temperature layers 1, 2, 3 and 4 Soil wetness levels 1, 2, 3 and 4 replaced by volumetric soil wetness layers 1, 2, 3 and 4 |
| 12 September 2000 | Field added is total column ozone; The ozone field is not currently based on any assimilated ozon data. Model deficiencies result in a serious overestimation of ozone in springtime at high latitudes. Change to 12 hour cycling of 4D-Var; this archive changed to be steps 003, 006, 009 and 012 from base times 0000 and 1200 UTC |
| 21 November 2000 | Internal data is represented on a N256 Quasi-regular Gaussian grid (256 lines between the pole and the equator, with varying numbers of points along each row) |
| 12 June 2001 | The model's ozone chemistry is improved in its representation of ozone loss by hetereogeneous processes that leads to the springtime ozone hole over the Antarctic |
| 9 April 2002 | SBUV and GOME data are now assimilated to improve the ozone field. |
| 7 October 2003 | Fields added are downward UV radiation at the surface, Photosynthetically active radiation at the surface, convective available potential energy. |
Order forms :
If you wish to make an order from this data set please download the following two Acrobat (PDF) files :| 1. Instructions and Standard Order forms (common for all data sets): |
24 KB |
| 2. Data Set Order form (to select data from this specific data set only) : |
12 KB  | 13.11.2003 |
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