Validation of ICON‐MIGHTI Thermospheric Wind Observations: 1. Nighttime Red‐Line Ground‐Based Fabry‐Perot Interferometers

Abstract

Observations of the nighttime thermospheric wind from two ground‐based Fabry‐Perot Interferometers are compared to the level 2.1 and 2.2 data products from the Michelson Interferometer Global High‐resolution Thermospheric Imaging (MIGHTI) onboard National Aeronautics and Space Administration's Ionospheric Connection Explorer to assess and validate the methodology used to generate measurements of neutral thermospheric winds observed by MIGHTI. We find generally good agreement between observations approximately coincident in space and time with mean differences less than 11 m/s in magnitude and standard deviations of about 20–35 m/s. These results indicate that the independent calculations of the zero‐wind reference used by the different instruments do not contain strong systematic or physical biases, even though the observations were acquired during solar minimum conditions when the measured airglow intensity is weak. We argue that the slight differences in the estimated wind quantities between the two instrument types can be attributed to gradients in the airglow and thermospheric wind fields and the differing viewing geometries used by the instruments.

The Effect of the Thermosphere on Ionosphere Outflows

“…New observations of thermosphere winds on a global scale are presently coming from the NASA Ionospheric Connection Explorer (ICON) (Immel et al, 2018). ICON is equipped with a Michelson interferometer, built by the NRL, that measures winds and temperatures in the altitude range 90-300 km (Harding et al, 2021;Makela et al, 2021). We are hopeful that newly accurate thermosphere now-casting data products might be developed.…”

Q2DW‐Tide and ‐Ionosphere Interactions as Observed From ICON and Ground‐Based Radars

“…The total ion densities are considered equivalent to electron densities, and are hereafter referred to as Ne. The winds are measured to a precision of order 1.2–4.7 ms −1 (Harding et al., 2017), and have been validated against G‐B measurements (Harding et al., 2021; Makela et al., 2021). The drift measurements are accurate to 7.5 ms −1 whenever O + densities are greater than 10 4 cm −3 (Heelis et al., 2017); this condition is met for all data analyzed here.…”

“…The total ion densities are considered equivalent to electron densities, and are hereafter referred to as Ne. The winds are measured to a precision of order 1.2-4.7 ms −1 (Harding et al, 2017), and have been validated against G-B measurements (Harding et al, 2021;Makela et al, 2021).…”

Gravity Wave Breaking Associated with Mesospheric Inversion Layers as Measured by the Ship-Borne BEM Monge Lidar and ICON-MIGHTI

“…Recent validation studies for ICON-MIGHTI thermospheric winds conducted using ground-based Fabry-Pérot Interferometers Makela et al [51] and specular meteor radars Harding et al [52] have demonstrated the utility of ICON winds for comparison with ground-based or ship-borne measurements.…”