# Metop-SG Radio Occultation sounder
*sensor . products*

GNSS radio occultation receiver mission on Metop-SG A satellites for atmospheric temperature and humidity profiles, planetary-boundary-layer and tropopause monitoring, surface pressure, and ionospheric electron-density profiles.

## Specifications
- **product status**: operational
- **manufacturer**: ruag-space
- **sensor**: {"frequency_bands_ghz":[1.17645,1.2276,1.57542],"measurement_principle":"passive","instrument_family":"radiometer","polarisation_modes":["RHCP"],"scan_type":"static","notes":"Modelled in the current sensor schema as a passive L-band GNSS receiver, following the existing STRATOS GNSS radio occultation row."}
- **deployment context**: orbital
- **entity type**: sensor
- **last verified date**: 2026-06-16
- **verified by**: agency-doc
- **claim status**: agency-sourced
- **provider**: ruag-space
- **attributes**: {"product_status":"operational","manufacturer":"ruag-space","sensor":"{\"frequency_bands_ghz\":[1.17645,1.2276,1.57542],\"measurement_principle\":\"passive\",\"instrument_family\":\"radiometer\",\"polarisation_modes\":[\"RHCP\"],\"scan_type\":\"static\",\"notes\":\"Modelled in the current sensor schema as a passive L-band GNSS receiver, following the existing STRATOS GNSS radio occultation row.\"}","kind":"sensor","deployment_context":"orbital","description":"GNSS radio occultation receiver mission on Metop-SG A satellites for atmospheric temperature and humidity profiles, planetary-boundary-layer and tropopause monitoring, surface pressure, and ionospheric electron-density profiles."}
- **relevance**: in-scope

## Editorial
The Metop-SG Radio Occultation sounder is the EPS Second Generation radio-occultation payload for atmospheric sounding from refracted GNSS signals.[^eumetsat-metop-sg-instruments] It supports retrievals for temperature, water vapour, planetary-boundary-layer height, tropopause structure, surface pressure, and space-weather electron-density information.[^eumetsat-metop-sg-instruments] The instrument is also known as GRAS-2 and tracks GPS, Galileo, and BeiDou signals.[^amt-gras2-2024] It uses L-band frequencies at 1.17645, 1.2276, and 1.57542 GHz with RHCP polarisation.[^wmo-ro-metop-sg] Daily performance figures include about 1500 soundings per day, 1900-2100 occultation measurements per day, and 2100 per day per instrument.[^wmo-ro-metop-sg][^amt-gras2-2024][^beyond-gravity-ro] The instrument performs GNSS radio occultation, demonstrated on Metop-SG A1.[^eumetsat-metop-sg-instruments]

## Compositional position
- metop-sg-a1 (missions) --[mission_payloads]--> Metop-SG Radio Occultation sounder

## Sources
- [eumetsat-metop-sg-instruments] | EUMETSAT Metop-SG instruments overview | https://www.eumetsat.int/metop-sg-instruments | tier=agency-doc | accessed=2026-06-16
- [wmo-ro-metop-sg] | WMO OSCAR instrument record: RO | https://space.oscar.wmo.int/instruments/view/ro | tier=agency-doc | accessed=2026-06-16
- [amt-gras2-2024] | The GRAS-2 radio occultation mission | https://amt.copernicus.org/articles/17/6213/2024/amt-17-6213-2024.pdf | tier=peer-reviewed | accessed=2026-06-16
- [beyond-gravity-ro] | Beyond Gravity radio occultation instruments | https://www.beyondgravity.com/en/satellites/electronic-solutions/radio-occultation | tier=operator-engineering | accessed=2026-06-16

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Source: https://eo-atlas.org/products/sensor/ro-metop-sg
Maintainer: SpectraWorks B.V. (CC-BY 4.0)