# Microwave atmospheric sounding
*sensing . methodologies*

Retrieval of atmospheric temperature and humidity vertical profiles from microwave emission in oxygen and water-vapour absorption bands (cross-track sounders).

## Specifications
- **family**: Passive microwave
- **entity type**: methodology
- **last verified date**: 2026-06-13
- **verified by**: agency-doc
- **claim status**: agency-sourced
- **subtype**: sensing
- **attributes**: {"family":"Passive microwave","summary":"Retrieval of atmospheric temperature and humidity vertical profiles from microwave emission in oxygen and water-vapour absorption bands (cross-track sounders).","kind":"sensing"}
- **technology**: microwave-radiometry
- **relevance**: in-scope

## Editorial
Microwave atmospheric sounding is the passive-microwave method used to retrieve atmospheric temperature and humidity vertical profiles from oxygen and water-vapour absorption-band emission. It is for atmospheric profiling when the question is vertical structure of the atmosphere, including data-assimilation inputs for numerical weather prediction, rather than surface imaging or precipitation mapping.[^noaa-nesdis-atms][^eumetsat-mws-science-plan]

The method depends on cross-track or nadir microwave sounders with oxygen-band channels for temperature structure and water-vapour channels around 183.31 GHz for humidity profiles. ATMS is a 22-channel cross-track sounder using 54 GHz and 183 GHz bands, while MWS extends the pattern to 24 channels from 23.8 to 229 GHz, including oxygen-band and 183.31 GHz channels.[^wmo-oscar-atms][^wmo-oscar-mws] This makes the methodology distinct from passive microwave imaging radiometry: the defining feature is absorption-band sounding for profiles, not broad surface-brightness imaging.[^wmo-oscar-atms][^wmo-oscar-mws]

Its operating advantage is day-night profile retrieval in many cloudy conditions. ATMS provides atmospheric temperature and moisture information and supports three-dimensional atmospheric profiles through clouds, and MWS is specified for temperature and humidity profile information in clear and cloudy regions.[^noaa-nesdis-atms][^eumetsat-mws-science-plan] The method still has coarse spatial and vertical resolution compared with imaging missions, and retrieval quality is constrained by precipitation and cloud-ice contamination.

Demonstrated implementations include the AMSU-A temperature sounder, AMSU-B and MHS humidity sounders, ATMS, MWS, FY-3 MWTS and MWHS variants, SAPHIR, and SSMIS-class combined imager-sounder instruments.[^noaa-class-atovs][^nsmc-mwts-i][^nsmc-mwhs-i][^nsmc-mwhs-ii][^noaa-mirs-saphir][^wmo-oscar-ssmis] SAPHIR narrows the pattern to tropospheric water-vapour profiling with six 183 GHz channels, while SSMIS combines imager and sounder functions with temperature and humidity channels in the 54 GHz and 183 GHz bands.[^noaa-mirs-saphir][^isro-megha-tropiques][^wmo-oscar-ssmis]

## Sources
- [noaa-nesdis-atms] | Advanced Technology Microwave Sounder (ATMS) | https://www.nesdis.noaa.gov/our-satellites/currently-flying/joint-polar-satellite-system/advanced-technology-microwave-sounder-atms | tier=agency-doc | accessed=2026-06-13
- [wmo-oscar-atms] | WMO OSCAR: Details for Instrument ATMS | https://space.oscar.wmo.int/instruments/view/atms | tier=agency-doc | accessed=2026-06-13
- [eumetsat-mws-science-plan] | EPS-SG MWS Science Plan | https://www-cdn.eumetsat.int/files/2020-04/pdf_science_epssg_mws_plan.pdf | tier=agency-doc | accessed=2026-06-13
- [wmo-oscar-mws] | WMO OSCAR: Details for Instrument MWS | https://space.oscar.wmo.int/instruments/view/mws | tier=agency-doc | accessed=2026-06-13
- [wmo-oscar-ssmis] | WMO OSCAR: Details for Instrument SSMIS | https://space.oscar.wmo.int/instruments/view/ssmis | tier=agency-doc | accessed=2026-06-13
- [noaa-class-atovs] | NOAA CLASS: TOVS/ATOVS data availability and instrument descriptions | https://www.class.noaa.gov/release/data_available/tovs_atovs/index.htm | tier=agency-doc | accessed=2026-06-13
- [nsmc-mwts-i] | NSMC: Micro-Wave Temperature Sounder-I (MWTS-I) | https://www.nsmc.org.cn/nsmc/en/instrument/MWTS-1.html | tier=agency-doc | accessed=2026-06-13
- [nsmc-mwhs-i] | NSMC: Micro-Wave Humidity Sounder-I (MWHS-I) | https://www.nsmc.org.cn/nsmc/en/instrument/MWHS-1.html | tier=agency-doc | accessed=2026-06-13
- [nsmc-mwhs-ii] | NSMC: Micro-Wave Humidity Sounder-II (MWHS-II) | https://www.nsmc.org.cn/nsmc/en/instrument/MWHS-2.html | tier=agency-doc | accessed=2026-06-13
- [wmo-oscar-mwts-3] | WMO OSCAR: Details for Instrument MWTS-3 | https://space.oscar.wmo.int/instruments/view/mwts_3 | tier=agency-doc | accessed=2026-06-13
- [noaa-mirs-saphir] | NOAA STAR MiRS: Megha-Tropiques SAPHIR instrument description | https://www.star.nesdis.noaa.gov/mirs/saphir.php | tier=agency-doc | accessed=2026-06-13
- [isro-megha-tropiques] | ISRO: Megha-Tropiques | https://www.isro.gov.in/Megha_Tropiques.html | tier=agency-doc | accessed=2026-06-13

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Source: https://eo-atlas.org/methodologies/microwave-atmospheric-sounding
Maintainer: SpectraWorks B.V. (CC-BY 4.0)