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GRM-01/40: NRT Refractivity Profile
(NRPMEA/NRPMEB)
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| _ | Values | Remarks |
| Units | Refractivity units (N) | _ |
| Domain | 0-50 km | Surface to
~1 hPa |
| Range | 0-450 N-units | _ |
Requirement on
target accuracy | 0-5 km: 0.6%-2%
5-30 km: 0.6%
30-50 km: 0.03 N-units | _ |
Requirement on
vertical resolution | 150-250 m | _ |
| GRM-01 status | Operational | Metop-A |
| GRM-40 status | Operational | Metop-B |
Current product version (GRM-01): 1.4
Previous product versions: 1.0 (demo), 1.1 (demo), 1.2 (pre-op), 1.3
Current product version (GRM-40): 1.4
Previous product versions: 1.0 (demo), 1.1 (demo)
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Product description
The NRT refractivity product contains a profile of neutral refractivity as a function of height (geometric and geopotential) above the EGM-96 geoid. GRM-01 contains refractivity from the GRAS instrument onboard Metop-A, GRM-40 from Metop-B.
Algorithm description
Each product profile is the result of one radio occultation. Signals from the occulting GPS satellite are measured by the GRAS receiver onboard the EPS/Metop satellite, downlinked, and processed by the ROM SAF into refractivity. More details can be found in the Algorithm Theoretical Baseline Document, on the Radio Occultation Theory page, and in the Validation Report for GRM-01 and GRM-40.
Data characteristics
GRAS measures about 700 GPS occultations per day. The product is output in both NetCDF and BUFR format, and disseminated via GTS/RMDCN (BUFR) and EUMETCast (NetCDF and BUFR). NetCDF files are also stored in the ROM SAF Product Archive.
Product validation and monitoring
Accuracy of the current version of the product is described in the Validation Reports. Daily monitoring of the processing and dissemination can be seen on the Monitoring Page.
Product documentation
All ROM SAF NRT and Offline products are described in the Product User Manual.
To retrieve this product please go to the Product Archive.
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