# Prototype Geostationary Interferometric Infrared Sounder
*sensor . products*

FY-4A MWIR/TIR geostationary interferometric infrared sounder for temperature and humidity sounding and water-vapour wind-profile derivation.

## Specifications
- **product status**: operational
- **deployment context**: orbital
- **manufacturer**: cma
- **sensor**: {"instrument_family":"passive-optical","measurement_principle":"passive","spectral_range_nm":{"min":550,"max":14200},"gsd_m":{"native":16000},"channels":[{"name":"LWIR","spectral_range_nm":{"min":8850,"max":14200},"gsd_m":{"native":16000}},{"name":"MWIR","spectral_range_nm":{"min":4440,"max":6060},"gsd_m":{"native":16000}},{"name":"VIS cloud-detection channel","spectral_range_nm":{"min":550,"max":900},"gsd_m":{"native":1000}}]}
- **entity type**: sensor
- **last verified date**: 2026-06-16
- **verified by**: agency-doc
- **claim status**: agency-sourced
- **provider**: cma
- **attributes**: {"kind":"sensor","product_status":"operational","deployment_context":"orbital","manufacturer":"cma","description":"FY-4A MWIR/TIR geostationary interferometric infrared sounder for temperature and humidity sounding and water-vapour wind-profile derivation.","sensor":"{\"instrument_family\":\"passive-optical\",\"measurement_principle\":\"passive\",\"spectral_range_nm\":{\"min\":550,\"max\":14200},\"gsd_m\":{\"native\":16000},\"channels\":[{\"name\":\"LWIR\",\"spectral_range_nm\":{\"min\":8850,\"max\":14200},\"gsd_m\":{\"native\":16000}},{\"name\":\"MWIR\",\"spectral_range_nm\":{\"min\":4440,\"max\":6060},\"gsd_m\":{\"native\":16000}},{\"name\":\"VIS cloud-detection channel\",\"spectral_range_nm\":{\"min\":550,\"max\":900},\"gsd_m\":{\"native\":1000}}]}"}
- **relevance**: in-scope

## Editorial
Prototype Geostationary Interferometric Infrared Sounder is a geostationary nadir infrared sounder flown on FY-4A for atmospheric temperature and humidity sounding and wind-profile derivation from water-vapour features [^wmo-giirs][^nsmc-fy4a]. It is not an imager: its core measurement is hyperspectral MWIR/TIR interferometric sounding, supported by a visible cloud-detection channel [^wmo-giirs][^nsmc-giirs]. The FY-4A configuration spans LWIR 700-1130 cm^-1, MWIR 1650-2250 cm^-1, and a 0.55-0.90 um visible channel; in wavelength terms, that is 8.85-14.2 um for LWIR, 4.44-6.06 um for MWIR, and 0.55-0.90 um visible context [^wmo-giirs]. Ground sampling is 16 km at sub-satellite point for the infrared sounding channels and 1 km for the visible cloud channel [^wmo-giirs]. For FY-4A, spectral resolution is 0.625 cm^-1; broader FY-4 generation values include 0.8 cm^-1 and 1.6 cm^-1, so those values are generation-specific when comparing FY-4A and later GIIRS products [^wmo-giirs][^nsmc-giirs]. The instrument is most relevant where geostationary atmospheric profiles, moisture fields, and water-vapour wind support matter more than fine spatial imaging [^wmo-giirs].

## Compositional position
- fy-4a (missions) --[mission_payloads]--> Prototype Geostationary Interferometric Infrared Sounder

## Sources
- [wmo-giirs] | WMO OSCAR instrument record: GIIRS | https://space.oscar.wmo.int/instruments/view/giirs | tier=agency-doc | accessed=2026-06-16
- [nsmc-giirs] | NSMC GIIRS instrument page | https://www.nsmc.org.cn/nsmc/en/instrument/GIIRS.html | tier=agency-doc | accessed=2026-06-16
- [nsmc-fy4a] | NSMC FY-4A satellite page | https://www.nsmc.org.cn/nsmc/en/theme/FY4A.html | tier=agency-doc | accessed=2026-06-16

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