# HY-2B Calibration Microwave Radiometer
*sensor . products*

Calibration microwave radiometer flown on HY-2B.

## Specifications
- **product status**: operational
- **deployment context**: orbital
- **manufacturer**: cast
- **sensor**: {"instrument_family":"radiometer","measurement_principle":"passive","frequency_bands_ghz":[18.7,23.8,37],"notes":"Frequency set follows the existing HY-2D Calibration Microwave Radiometer candidate; verify during full sensor research."}
- **entity type**: sensor
- **last verified date**: 2026-06-16
- **verified by**: agency-doc
- **claim status**: agency-sourced
- **provider**: cast
- **attributes**: {"kind":"sensor","product_status":"operational","deployment_context":"orbital","manufacturer":"cast","description":"Calibration microwave radiometer flown on HY-2B.","sensor":"{\"instrument_family\":\"radiometer\",\"measurement_principle\":\"passive\",\"frequency_bands_ghz\":[18.7,23.8,37],\"notes\":\"Frequency set follows the existing HY-2D Calibration Microwave Radiometer candidate; verify during full sensor research.\"}"}
- **relevance**: in-scope

## Editorial
HY-2B Calibration Microwave Radiometer (CMR) is a passive microwave radiometer flown with the HY-2B ocean altimetry mission for radar-altimeter water-vapour correction.[^wmo-hy2b][^wmo-cmr] CMR uses three frequencies: 18.7, 23.8, and 37 GHz.[^wmo-cmr][^mdpi-hy2-cmr-calibration] Within its retrieval role, 23.8 GHz supports atmospheric water-vapour retrieval, 37 GHz supports cloud liquid water retrieval, and 18.7 GHz captures sea-surface wind and roughness contributions.[^mdpi-hy2-cmr-calibration] The instrument is capable of passive microwave radiometry for altimeter path-delay correction.[^wmo-cmr] HY-2B also carries a separate five-frequency Scanning Microwave Radiometer; CMR is the three-frequency altimeter-correction instrument, not that SMR payload.[^wmo-hy2b][^wmo-cmr]

## Compositional position
- hy-2b (missions) --[mission_payloads]--> HY-2B Calibration Microwave Radiometer

## Sources
- [wmo-hy2b] | WMO OSCAR satellite record: HY-2B | https://space.oscar.wmo.int/satellites/view/hy_2b | tier=agency-doc | accessed=2026-06-16
- [wmo-cmr] | WMO OSCAR instrument record: Calibration Microwave Radiometer | https://space.oscar.wmo.int/instruments/view/cmr | tier=agency-doc | accessed=2026-06-16
- [mdpi-hy2-cmr-calibration] | On-orbit calibration method for correction microwave radiometer of the HY-2 satellite constellation | https://www.mdpi.com/2072-4292/15/24/5643 | tier=peer-reviewed | accessed=2026-06-16

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Source: https://eo-atlas.org/products/sensor/hy-2b-cmr
Maintainer: SpectraWorks B.V. (CC-BY 4.0)