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Operational Pressure Level 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 at each level is stored as a field either of grid point values, or of spherical harmonic coefficients;
- spherical harmonic coefficients are stored as defined by code figure 1 in tables 9 and 10 of FM 92-IX Ext GRIB;
-
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 representation is in spherical harmonics with triangular truncation at wave number 63 (T63). Data is short term forecasts from times 0000, 0600, 1200 and 1800 UTC Forecasts step available is 006 hours 14 standard pressure levels, 1000, 850, 700, 500, 400, 300, 250, 200, 150, 100, 70, 50, 30 and 10 hPa Fields available are geopotential, temperature, vertical velocity, u- and v-components of horizontal wind, relative vorticity, divergence, specific humidity and relative humidity |
| 1 May 1985 | Internal data representation is in spherical harmonics with triangular truncation at wave number 106 (T106). |
| 12 February 1991 | Step 003 added to forecast steps |
| 17 September 1991 | Internal data representation is in spherical harmonics with triangular truncation at wave number 213 (T213). |
| 1 January 1992 | Added pressure level, 925 hPa |
| 4 April 1995 | Specific humidity archived on a N160 Quasi-regular Gaussian grid (160 lines between the pole and the equator, with varying number of points along each row) from this date. |
| 1 April 1998 | Internal data representation is in spherical harmonics with triangular truncation at wave number 319 (T319). |
| 9 March 1999 | Added pressure levels 20, 7, 5, 3, 2, 1 hPa |
| 12 September 2000 | Added field ozone mass mixing ratio, this field is archived on a Gaussian grid. 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 steps 003, 006, 009 and 012 from base times 0000 and 1200 UTC. |
| 21 November 2000 | Internal data representation is in spherical harmonics with triangular truncation at wave number 511 (T511). Gaussian fields are represented on an N256 Quasi-regular Gaussian grid (256 lines between the pole and the equator, with varying number of points along each row). |
| 12 June 2001 | Added field potential vorticity which is archived on a Gaussian grid. 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. |
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) : |
 | 13.11.2003 |
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