This article was accepted into the corpus but its outbound wikilinks were never NER-processed — typical at the deepest BFS hop or when the run's entity cap was reached. No expansion funnel to show.
| Microwave Humidity Sounder | |
|---|---|
| Name | Microwave Humidity Sounder |
| Abbreviation | MHS |
| Manufacturer | European Space Agency / National Aeronautics and Space Administration contractors |
| Mission | NOAA-18, NOAA-19, MetOp-A, MetOp-B, MetOp-C |
| Type | Microwave radiometer |
| Wavelength | millimeter-wave (~50–190 GHz) |
| Function | tropospheric humidity sounding |
Microwave Humidity Sounder The Microwave Humidity Sounder is a spaceborne millimeter-wave radiometer designed to observe atmospheric water vapor and related thermodynamic variables for operational National Oceanic and Atmospheric Administration and research European Organisation for the Exploitation of Meteorological Satellites programs. Developed as a descendant of instruments flown on Nimbus 6, TIROS-N, and NOAA-15, it provides channelized radiance measurements used in numerical weather prediction by agencies such as Met Office, European Centre for Medium-Range Weather Forecasts, and Japan Meteorological Agency.
The instrument suite addresses vertical profiling of humidity and cloud-affected brightness temperatures through channels near water vapor lines used by retrievals in Global Forecast System and Integrated Forecast System assimilation. MHS objectives align with goals set by the World Meteorological Organization for satellite-based humidity sounding and are integrated into international programs like the Global Observing System and International Satellite Cloud Climatology Project.
MHS employs heterodyne and direct-detection radiometer architectures operating across channels centered near 89 GHz, 157 GHz, and 183 GHz water vapor features, hardware concepts refined during projects at Jet Propulsion Laboratory and component suppliers such as Rafael Advanced Defense Systems-contracted microwave groups. The optical assembly uses a conical scan reflector tied to attitude references from Inertial Measurement Unit suites and star tracker data from platforms like MetOp-A. Radiometric calibration uses internal blackbody loads and space views, referencing temperature standards traceable to National Institute of Standards and Technology, and noise characterization follows methods developed for Advanced Microwave Sounding Unit heritage instruments.
MHS units have flown on polar-orbiting satellites including NOAA-18 and NOAA-19 in the National Oceanic and Atmospheric Administration series and on the MetOp series (MetOp-A, MetOp-B, MetOp-C) operated by EUMETSAT. The instrument complements other payloads such as the Advanced Microwave Sounding Unit, Infrared Atmospheric Sounding Interferometer, and Global Navigation Satellite System radio occultation receivers on the same platforms. Mission planning and data dissemination involve coordination between EUMETSAT, NOAA, and research centers including the Cooperative Institute for Meteorological Satellite Studies.
Primary MHS data products include calibrated brightness temperatures and level-2 geolocated radiance swaths. Retrieval algorithms implement statistical and physical inversion techniques developed at institutions like University of Wisconsin–Madison, Met Office Hadley Centre, and National Center for Atmospheric Research, assimilating MHS radiances into models such as GFS and IFS. Ancillary products combine MHS with microwave imagers and hyperspectral sounders to produce integrated humidity profiles, cloud liquid water path, and precipitation-related diagnostics used in products distributed via NOAA Comprehensive Large Array-data Stewardship System and EUMETCast.
Calibration strategies use cold space views, internal hot loads, and vicarious cross-calibration against reference instruments such as Advanced Microwave Sounding Unit and ground-based radiometers from networks like ARM Climate Research Facility and Global Climate Observing System. Validation campaigns co-locate MHS overpasses with radiosonde launches from operational centers including NOAA ESRL and research facilities like Scripps Institution of Oceanography and WMO/GAW stations to quantify biases, stability, and inter-satellite consistency. Inter-calibration efforts involve teams at NASA Goddard Space Flight Center and EUMETSAT.
MHS radiances contribute to short- and medium-range forecasting improvements in humidity-sensitive convective and tropical cyclone cases analyzed by National Hurricane Center, Joint Typhoon Warning Center, and regional forecast centers. Climate monitoring uses long-term MHS records as part of integrated datasets maintained by NOAA National Centers for Environmental Information and Copernicus Climate Change Service to study trends in tropospheric moisture and hydrological cycle signals in conjunction with records from TRMM and GPM missions. Research applications include assimilation experiments at ECMWF, process studies at NCAR, and data fusion projects with SMAP and Aqua instruments.
Limitations include sensitivity to cloud liquid water and precipitation contamination, channel saturation near the 183 GHz core, and inter-satellite calibration drift that impacts climate applications—a focus of improvement efforts by groups at EUMETSAT, NOAA, and European Space Agency. Future developments aim to enhance radiometric stability, expand spectral coverage with hyperspectral microwave concepts pursued by ESA and NASA programs, and integrate MHS-like channels into multi-instrument constellations supporting Global Precipitation Measurement follow-ons and next-generation polar platforms.
Category:Weather satellite sensors