At 5:04 PM local time (2104 UTC) on 1 July 2025, the newest member of the geostationary ring was launched into orbit. The MTG-S1 satellite (to be renamed Meteosat 13 upon commissioning) represents a first for EUMETSAT: a hyperspectral sounder in geostationary orbit. While EUMETSAT has long supported hyperspectral sounders in low-earth orbit with the Infrared Atmospheric Sounding Interferometer (IASI) aboard the MetOp series of satellites, the Meteosat Third Generation Infrared Sounder (MTG-IRS) will, for the first time, provide continuously updated hyperspectral observations over Europe.

Hyperspectral infrared observations are some of the most impactful inputs into numerical weather models as they contain information about the spatial and vertical distribution of temperature, water vapor, and clouds. Level 2 products will retrieve profiles of temperature, humidity, and other atmospheric characteristics from these spectra.

MTG-IRS promises 1953 channels across the middle and longwave portions of the infrared spectrum. While IASI observes more channels and and a broader, more continuous spectrum, the much improved temporal resolution that is possible from geostationary orbit will enable forecasters to monitor rapidly-evolving environments and scientists to unlock new understanding of key atmospheric processes. The scanning strategy for MTG-IRS involves repeating over a sequence of four local area coverage (LAC) regions. The region over Europe, LAC4, will be sampled every 30 mins, while the other regions will be sampled in small bursts separated by a few hours. For more on MTG-IRS and its scan strategy, visit the Data Guide.

The satellite also supports the Sentinel 4 mission, which will monitor trace gasses and aerosols from geostationary orbit. This will be accomplished through the Ultraviolet-Visible-Near IR (UVN) imaging spectrometer mounted aboard the satellite, which will provide approximately hourly views over Europe. More about Sentinel 4 is available here.

While many EUMETSAT launches are handled by the ESA launch facility in French Guyana (for example, MTG-I1), the launch for this payload was contracted out to Space-X and launched from the Kennedy Space Center. The same launch pad, 39A, that supported flights to the moon and numerous Space Shuttle flights was used for this trip to geostationary orbit. As is common with launches from Kennedy Space Center, this area was well-sampled by a GOES-19 mesoscale scan. The true color view from SSEC Real Earth shows the brief rocket plume that was present right after launch; it dissipated within just a few minutes.

Interestingly enough, the plume is also visible on the SO2 RGB imagery as a distinctly different color than the existing cloud coverage to the southeast. The SO2 signature is also present longer than the visible plume is. Note how there is also a brief flash of the plume in the far upper right corner of the animation right at launch time that is not present on the true color view.

Other satellite signatures of the MTG-S1 launch can be seen in this blog post.

The United States is hoping to launch a geostationary hyperspectral spounding satellite to cover a swath of the western hemisphere with similar capabilities as part of the GeoXO program that will replace the current generation of GOES satellites. The launch is anticipated in the early 2030s and is projected to revolutionize nowcasting, forecasting, and atmospheric science upon becoming operational.

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A major explosion at a fireworks warehouse in Esparto, California occurred late in the afternoon on 01 July 2025, injuring 2 with 7 people remaining unaccounted for (media report). The robust thermal signature of the resulting fire was detected by the Next Generation Fire System (NGFS), using both 1-minute Mesoscale Domain Sector GOES-18 (GOES-West) images (above) and 5-minute CONUS Sector GOES-19 (GOES-East) images (below). The initial GOES-18 NGFS detection occurred at 0049 UTC (5:49 PM local time), with a cursor sample indicating that the Fire Radiative Power value was 1816.57 MW.

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The areal extent of the smoke plume emanating from the post-explosion fire was shown in larger-scale views of CSPP GeoSphere True Color RGB images from GOES-18 (above) and GOES-19 (below). GOES-18 imagery revealed that two additional explosions occurred, as indicated by small bursts of pyrocumulus clouds beginning at 0142 UTC and 0201 UTC.

Thanks to Todd Beltracci, The Aerospace Corporation, for alerting us to this event.

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The EUMETSAT MTG-S1 satellite was launched from Kennedy Space Center, Florida at 2104 UTC on 01 July 2025 — using a SpaceX Falcon 9 rocket. A thermal signature of the Falcon 9 Stage 1 rocket booster (as well as the Stage 2 rocket, after separation from the booster just before 2106 UTC) was apparent in 1-minute Mesoscale Domain Sector Rocket Plume RGB images (created using Geo2Grid) from GOES-19 (GOES-East) (above) and GOES-18 (GOES-West) (below). More details about the hyperspectral sounder instrument on MTG-S1 are available in this blog post.

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In 1-minute multi-panel displays of all 16 ABI spectral bands from GOES-19/GOES-East (above) and GOES-18/GOES-West (below), a brighter thermal+reflectance signature of the Falcon 9 rocket booster was evident in all Near-Infrared bands (03-06) along with a warmer thermal signature in all Infrared bands (07-16) — most notably at 2105 UTC (GOES-19 | GOES-18), although the signature in Near-Infrared band 03 imagery was quite subtle (and located directly over a narrow low-altitude cloud feature in the GOES-18 view). The thermal signature was very prominent in the Shortwave Infrared band (07) due to that spectral band’s greater sensitivity to higher temperatures — as well as in the Water Vapor infrared bands (08/09/10), since the rocket exhaust plume contained a large amount of superheated water vapor.

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1-minute GOES-18 and GOES-19 True Color RGB images from the CSPP GeoSphere site (above) revealed that the Falcon 9 rocket booster condensation cloud plume quickly dissipated just off the Florida coast — due to the combination of dry air and wind shear at high altitudes (above the 300 hPa pressure level), as seen in a plot of rawinsonde data from Cocoa Beach (KXMR) (below).

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True Color imagery over western Japan, above, from three JPSS Satellites (from the NASA Worldview site) show a region with a hazy signature that appears to originate over Kyushu’s main cities of Kumamoto and Fukuoka. Winds at this time are relatively light, as evidenced by the NOAA-21 image, shown below, that includes a dark region within the sun glint (see this blog post for another discussion of diagnosing light winds within areas of sun glint).

Advanced Scattermeter (ASCAT) data from a fortuitous overpass from Metop-B (source), shown below, confirms the region of very light winds around Kyushu.

Aerosol Optical Depth (scaled from 0-5) computed from Suomi NPP and NOAA-20 is shown below. The haze does not appear to be from active fires based on this animation of shortwave infrared imagery from Himawari-9.

Air Quality Indices, below, (from this site), show the worst near-surface Air Quality over southern Kyushu. This is a good reminder that satellite detection of AOD views the entire atmosphere — to get the best description of Air Quality, use both surface and satellite detection.

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Editor’s Note: This is my last contribution to the CIMSS Satellite Blog, as I am retiring today after 30 years (plus 1 month, a week and a day) with the University of Wisconsin-Madison. It has been a great honor to talk about beautiful and informative satellite imagery in this space, starting in 2006 with this blog post on Parallax. I hope my writings (1) have been helpful and (2) have been accurate. It’s honestly the best job I could imagine having!

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