VIS0.64, Rocket Plume RGB, Airmass, VIS0.63, High Resolution Visible
Meteosat Third Generation's launch on 13 December 2022 could be tracked in satellite imagery from GOES-16 and MSG.
23 December 2022
21 December 2022
By Ivan Smiljanic, Dan Lindsey and Steven Miller (CIRA), HansPeter Roesli and Mark Higgins
The beautiful launch of the MTG-I1 satellite took place from Kourou on Tuesday 13 December at 20:30 UTC. With largely clear blue skies in the background, spectators had an excellent view the first few minutes of the satellite voyage, even after the moment of separation of two side rocket boosters of Ariane 5 rocket (ca. 2:20 min into the flight).
Due to a courtesy of NOAA, and the great capabilities of the ABI instrument onboard the GOES-East satellite, we witnessed an equally beautiful launch from 36,000km up in space. Following requests, NOAA kindly decided to turn the sharp eyes of GOES-16 satellite over the wider French Guiana area, scanning the smaller domain every minute with the Mesoscale Domain Sector.
The first view on the launch came after only a few hours, via the GOES Program Scientist, Dan Lindsey. On the VIS0.64 channel image at resolution of 500m (Figure 1), the rocket plume was seen extending towards the east and, also, bending due to a vertical wind shear.
Often, optically thin higher level clouds (e.g. cirrus, contrails) are not detectable due to high transparency in the visible spectral range, however, their shadows can be seen on the low laying (stratiform) clouds. This time the rocket plume cloud cast a shadow over the highest of the tropospheric clouds. The shadow was seen as a linear darker shape over the cirrus cloud band, just north of the rocket path (due to low Sun position in the west-south-west) (Figures 2a and 2b).
Tracking the warm plume thermal signal makes it possible to follow the rockets actual position/path during several one minute scans. The Rocket Plume RGB is a dedicated RGB product that utilises IR3.8, WV6.2 and NIR1.6 channels respectively, shown in Figures 3 and 4.
The initial plume signal was red while the rocket was in the lower troposphere (predominant signal from red IR3.8 component), turning into the green to yellow shades (predominant contribution from WV6.2 channel) once the rocket penetrated the upper troposphere, and higher. High clouds are shown in black (to red shades for thinner clouds), middle glaciated clouds in green, low water clouds in blue, and cloud free areas in yellow hues.
The rocket plume's thermal signal was also apparent with the standard Airmass RGB product (Figure 5), especially once the rocket reached the higher troposphere (shown in red to orange shades).
Spectral channels of the Ash RGB (Figure 6) and SO2 RGB (Figure 7) indicated an SO2 signal in the rocket plume (green plume in both products means presence of sulfuric gas), but only during (roughly) first minute of the flight. At 20:31 the imagery shows a hot spot and the 20:32 scan shows the SO2 trail, but only out to about where the hot spot was a minute earlier.
It is suspected that the SO2 trail is coming from the solid boosters that separated after 2:20 mins/secs into the launch (timing from the ESA video). The absence of SO2 after booster burn-out and its dispersion close to the launch site afterwards could make sense, as the main engine Vulcain is a LOX/LH device that is not supposed to exhaust SO2 or similar gases. However, this sharp change in plume colour could be due to different factors (e.g. width and optical thickness of the plume, or, for instance, change in ambient temperature). Hence, to determine the real reason of colour change one would need close analysis of different parameters like fuel chemistry, vertical temperature profile along the flight, exact GOES scanning time and exact rocket height at each moment.
Figure 8 shows a collection of sandwich products created by merging the ABI VIS0.64 channel (at 500m resolution) and various RGB products (Airmass, Tropical Airmass, Ash, Cloud Phase and Rocket Plume), during first few scans of the launch. High resolution information from the visible channel, with the spectral signatures of different ABI channels (RGBs), gives a more informative and very vivid image of the MTG-I1 satellite launch.
Could a Meteosat Second Generation satellite (MSG) witness the birth of its heir? In theory yes, since the nominal European GEO satellites have French Guiana and most of the Atlantic Ocean in their field of view. However, the slant view (reduced resolution), scanning time, and overall spatial resolution of SEVIRI instrument can make it difficult for a rocket signal (visual or thermal) to be detected.
Figure 9 is showing the Meteosat-11 HRV channel's view on the launch. Comparison with VIS0.64 channels of ABI (at similar scanning times) makes it easier to understand that, in fact, both rocket plume and the plume shadow were visible through the eyes of an MSG satellite!