Researchers at the Cooperative Institute for Meteorological Satellite Studies (CIMSS) maintain a webpage with spectral response function data and related information for current and past instruments. At the request of a research scientist from NASA Langley Research Center, we updated the web page for past instruments: GMS-5 from the Japan Meteorological Agency (JMA), as well as Meteosat-5 and -7 from the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT). The web page has figures of spectral response functions (SRFs) and the SRF files in text format interpolated to 0.1 inverse centimeter wavenumber spectral spacing. There are also files with the central wavelength, central wavenumber, and bandwidths as determined by the full-width half-max (FWHM) values for the SRF. Planck function coefficients for each infrared band used for converting radiance into brightness temperature are also included.

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  Figure: Spectral Response Functions (SRF) for the two infrared channels on Meteosat-5, which had a visible band (not shown) in addition to the Infrared Window and Water Vapor bands shown here.

Pre-operational L1 data from the Meteosat Third Generation InfraRed Sounder (MTG-IRS) became available on 31 July.  Various evaluation results were presented at the IGARSS conference in Washington DC the week of August 10, including noise, spectral calibration, and radiometric calibration performance.  Preliminary assessments are very encouraging.  An example result is shown in the attached figure which compares IRS with CrIS using simultaneous nadir and non-nadir overpassess of the IRS observation region by NOAA-21 and NOAA-20, demonstrating very good radiometric agreement between the sensors.

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  Figure: Mean IRS and CrIS brightness temperature spectra and mean brightness temperature differences using simultaneous overpass data between 1 and 10 August 2026.

The Cooperative Institute for Meteorological Satellite Studies (CIMSS) Satellite Blog was updated with the following posts: “Tropical Storm Lala becomes a Category 1 Hurricane south of the Big Island of Hawai`i” (Aug. 15), “Significant Flooding Strikes Central Indiana” (Aug. 17), “Mukluk Fire near Tok, Alaska forces evacuations” (Aug. 17) and “After Becoming a Snowstorm, Lala Reinvigorates Itself to Become Category 4 Hurricane” (Aug. 19).

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  Figure: GOES-18 Infrared Window image of Hurricane Lala at 1435 UTC on August 19, 2026 -- showing Hurricane Lala in the Pacific Ocean, shortly after weakening from its peak intensity as a Category 4 tropical cyclone.
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  Figure: NOAA-21 VIIRS GeoColor RGB image with an overlay of Next Generation Fire System (NGFS) Fire Detection polygons at 2215 UTC on August 17, 2026 -- showing the thermal signature of the Mukluk Fire, which forced evacuations in the Tok, Alaska area.