Can Geostationary Imagers See Noctilucent Clouds?

June 20th, 2022 |

Q: Can geostationary imagers see the very thin, very high Noctilucent Clouds? A: Yes and no, depending on the satellite, how data are processed, time of the year, time of the day and spectral band. Thanks to Simon Proud for this tweet using JMA‘s Advanced Himawari Imager (AHI):

Note the very thin line near the top of the images on June 20, 2022. These images are derived from Japan’s AHI. A animated gif version.
A similar loop as above, but more zoomed in. From June 20, 2022. These images are derived from Japan’s AHI. An animated gif version.
A “spectral” loop of AHI’s three visible bands at 15 UTC on June 20, 2022. A animated gif version.

Since NOAA’s ABI is a similar instrument to AHI it seems likely that ABI can also observe noctilucent clouds at times. Noctilucent clouds are possibly only observable in visible bands when they are off the earth’s edge, with space as a background, and when illuminated from certain angles. However, due to ground system processing in the generation of the ABI radiance files, most users cannot see data that the ABI scans off the Earth’s edge in space. Special processing of ABI data does allow to show off Earth pixels, such as in these examples with the moon and the Webb Space Telescope plume in space. Recall that the AHI Full Disk is made up of 23 swaths (as opposed to 22 for the ABI), so it scans a bit more space both north and south of the Earth.

An animation including the AHI 3.9 micrometer band shows the relationship between the Earth’s edge and the apparent cloud location. (A animated gif version.) Consider also the large apparent displacement of these high altitude (“shining at night”) clouds due to parallax.

Also see this image:

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