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EPS Weather Parameter products
The EPS WEATHER PARAMETER products in the form of time series of a specific parameter for a number of forecasts at the user defined location are available from the ECMWF dissemination system. Data is presented in the FM 94-IX Ext. BUFR binary representation (BUFR Edition 3 is used).
Each EPS WEATHER PARAMETER product contains 51 data subsets. Each subset represents data time series for a particular forecast: EPS control forecast and each of the 50 EPS T639 (for forecast range 0-240 hours) and T319 (for time steps 246-360 hours) perturbed forecasts. WEATHER PARAMETER forecast time steps range from 0 to 240 or 360 hours by steps of 12, 6 or 3 hours (3 hourly intervals are available up to forecast step 144 and then the values are taken 6 hourly to T+240 or T+360).
The data for the WEATHER PARAMETER products is constructed from the basic model grid used for producing many of the standard dissemination fields. Where the requested location coordinates coincide with the original field grid point location, the grid point value will be
taken. Otherwise, the value at the requested location will be obtained by bi-linear interpolation from the four nearest original field grid points.
When requesting data at grid point location note the following:
- upper air fields are converted from spherical harmonics to 0.25/0.25 (leg 1) and 0.5/0.5 (leg 2) degrees latitude/longitude grid before extraction/interpolation to requested location;
- surface fields out of EPS T639 forecasts (control and perturbed) are represented on N320 reduced Gaussian grid whereas surface fields out of EPS T319 forecasts (VarEPS leg 2) are represented on N160 reduced Gaussian grid;
A number of parameters have been made available for dissemination in the form of WEATHER PARAMETER products. The system has been made fully flexible, so that any combination of parameters/levels/locations can be requested. Parameters available are listed in the Table 5.10 below.
* Orography is defined as Geopotential on level surface** On pressure levels 1000, 850, 700, 500 and 200 hPa. See note below for time range availability
*** WP Sunshine duration are not accumulated values but values since previous time step specified in the message
++ Takes into account time step frequency requested and generates fields accordingly
Table 5.10 EPS WEATHER PARAMETER products
NOTE: WEATHER PARAMETER products are generated on either 3, 6 or 12 hour intervals (0 to 240 or 0 to 360). The following products are available only at 12 hour intervals:
- Geopotential on pressure levels 1000, 700 and 200 hPa
- Temperature on pressure levels 1000, 700 and 200 hPa
- U-velocity, V-velocity and Relative humidity on pressure levels 1000, 850, 700, 500 and 200 hPa.
EPS WEATHER PARAMETER products are disseminated separately from other EPS products and have their own dissemination schedule (Table 5.14 below).
EPS Weather Parameter requirements
The following command language parameters are specific for the WEATHER PARAMETER requirements. Other parameters are listed under the general EPS requirements above.
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gives range of forecast time steps (see note above for each parameter/level availability); 240 (will result in 3 hourly values to T+144 and 6 hourly to T+240) 360 (will result in 3 hourly values to T+144 and 6 hourly to T+360) |
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BUFR definition for WEATHER PARAMETER products
ECMWF's EPS WEATHER PARAMETER products are presented in the FM 94-IX Ext. BUFR binary representation form. Products are coded into BUFR Edition 3. They contain the following:
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Pressure data (Element present only for upper air |
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240 data set (21 - 12hourly data set, 41 - 6 hourly data set or 65 - 3 hourly data set) 360 data set (31 - 12hourly data set, 61 - 6 hourly data set or 85 - 3 hourly data set) |
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Minimum temperature at 2m, past 6 hours Pressure reduced to mean sea level |
Each BUFR message for EPS WEATHER PARAMETER data conforms to the above data description and contains 51 data subsets. Each subset represents data time series for a
particular forecast: EPS control forecast and each of the 50 EPS perturbed forecasts.
Please, note that two new entries have been added to the BUFR table B:
1 008195 DATA TYPE CODE TABLE 08195
2 005195 ENSEMBLE MEMBER NUMBER NUMERIC
DATA TYPE code entries (as defined in the code table 08195 and used for WEATHER PARAMETER products):
ENSEMBLE MEMBER NUMBER values (as used for WEATHER PARAMETER products):
0 = operational T1279 forecast/EPS control forecast
n = EPS perturbed forecast (n = 1 - 50)
Users have to update their tables accordingly. Tables are also available from ECMWF.
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18-01-2011 |
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© ECMWF |
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