MIGHTI v5 wind product now processing

It's a very exciting update!

Version 5 of the MIGHTI thermospheric winds is on its way. We are currently processing all the line of sight winds and once these are approved, will be promoted to the public FTP site and then the NASA archive. This wind product fills some long data gaps bad due to solar contamination. In version 5 the effects of this contamination has been mitigated and most of the data has been recovered. It also un-tethers the zero wind from HWM, using the on-orbit calibration processes to determine zero.

This figure shows the v04 and v05 wind retrievals during the same period of time in late 2020. This is the 2.1 product (Line of Sight Winds) from MIGHTI-A for ~ 48 days (the orbital precession period) of descending node observations at 244 km altitude. You can note several differences. First, the terminator transitions are much less abrupt. This comes from the fact that the interferometer fringes shift with scene brightness, still a puzzling aspect of the instrument performance. This has been characterized and is included in the new retrievals. Second, you can see that the high winds in the morning are much reduced, in part due to this change as well.

What is more is that the v04 product used an approximate and nearly constant zero wind, based on HWM. With this, systematic errors were introduced and accuracy suffered. In version 5, the HWM-based correction for the zero wind phase has been replaced with a self-calibration, improving the accuracy to ~10-25 m/s (see the documentation upon release for more details). A Space Science Reviews paper describing the v5 wind product is also in work.

The data quality flags at the terminator should still be respected in using the data, but there is going to be a larger number of usable data there as well.

These are being processed up to 2.2 (Cardinal Winds) in the coming week and should be approved shortly after that. I then expect them to then appear on the FTP site in November of 2022. We'll then work to stay on track to have no more than a 6-month release delay from now on.

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