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Background

Since 2005, ECMWF has generated model-simulated satellite images from the 00 UTC and 12 UTC  cycles of the operational HRES forecast out to five days for all operational geostationary satellites (i.e., MET-7, MET-10, MTSAT-2, GOES-13 and GOES-15). The simulated images are archived in MARS as GRIB edition 1 files and have been presented on the ECMWF website as PostScript image files. The forecast-generated satellite images have been based on the resolution of the HRES global model with 3-hourly output from T+0 to T+48 and 6-hourly output to step=120.

Up to and including IFS cycle 41r1, the satellite images in both the window and water vapour (WV) channels were simulated over each of the 5 geostationary satellite’s disk. Brightness temperatures were calculated using the same radiative transfer algorithm (RTTOV-11) as in the operational data assimilation and using the relevant atmospheric model profiles (temperature, specific humidity, ozone mass mixing ratio, cloud cover, specific cloud liquid water content, specific cloud ice water content, specific rain water content, specific snow water content) and the relevant surface parameters (skin temperature, 10m u and v wind components, 2m temperature and 2m dewpoint temperature, volumetric soil water layer 1, convective available potential energy).

Errors in simulated satellite images can derive from errors in the NWP parameters, on which the simulation is based, the resolution of the model and RTTOV model performance.

Updates to the simulated satellite images at IFS cycle 41r2

The simulated satellite images at IFS cycle 41r2 are enhanced in various aspects, as summarised below.

Are global satellite images capturing detailed cloud and/or humidity features. The new simulated images product shows the high-resolution ECMWF forecasts as a weather satellite will see it (e.g. Meteosat-10). The new simulated satellite image product includes latitudes greater than 60 degrees north and south, extending the geostationary-type imagery over high-latitude regions. This is an enhancement with respect to the old satellite image product limited to the Meteosat-10 disk domain.

Assume a nadir view for every model grid point. The new simulated satellite images assume a nadir view for every model grid point so the effect of looking slantwise through the atmosphere is neglected. Consequently the atmosphere appears less opaque than with the old simulated images and so lower lying clouds and other features are better presented.

Are produced in post-processing within IFS, with no mapping on satellite grid. This is a technical advantage of the new simulated satellite images being now produced in the post-processing within the IFS and being part of the research tests for operational release. This is an enhancement with respect to the previous product generated only in the early delivery cycles of the operational suite as can be now routinely used in RD experiments to validate model developments which affect the temperature and moisture fields.

Availability of the simulated satellite images in MARS. The new images product are archived in MARS in GRIB edition 2 and are available at every post-processing step, out to 240 hours: 3 hourly in the beginning (0-h to 48-h), then 6 hourly (48-h to 12-0h), then 12 hourly (120-h to 240-h). This is an enhancement with respect to the old satellite image product available in GRIB edition 1, out to 120-h forecast.

Availability of the simulated satellite images in ECMWF Catalogue and dissemination. The timeliness of delivery is optimal for dissemination. The new simulated images will be added to the list of products that can be requested in dissemination.

  • The updated simulated satellite images introduced at IFS cycle 41r2 are global whereas the previous images showed only the disks visible to the geostationary satellites.
  • The images are no longer "geostationary" but includes latitudes greater than 60 degrees north and south so covers polar regions
  • The updated images will be made available in dissemination
  • It will be possible to both retrieve sub-areas of the images from MARS and request sub-areas in dissemination.
  • Only images corresponding to the Meteosat-10 channels 5, 6 and 9 are available. 
  • The images corresponding to the GOES and HIMWARI satellites that were available at IFS cycle 41r1 are discontinued.

Availability of the simulated satellite images in dissemination

 

Availability of the simulated satellite images in MARS

 

 

 

 

 

 

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