Evaluating the Capability of ICON-MIGHTI to Detect Plasma Bubbles in the Ionosphere

The MIGHTI airglow imager onboard the ICON spacecraft in LEO was built to make remote thermospheric windspeed measurements at low latitudes. The MIGHTI team, when reviewing the data, observed variations in day-to-day brightness potentially indicative of plasma bubbles: regions of low-density E-region plasma which rise through the F-region and cause radio scintillation that interferes with communications and GPS performance. Here, we explore the possibility of MIGHTI observing plasma bubbles by using its red-line airglow measurements to attempt to detect this phenomenon. Small-scale structuring indicative of plasma bubbles is searched for by comparing measurements between MIGHTI's two identical imagers, which make remote airglow measurements at the same region from perpendicular directions. The usability of the two imagers for this purpose is assessed, given they are not calibrated to measure absolute airglow brightness, and it is determined that the level of disagreement between them does not prevent these comparisons. The evolution of the ionosphere in the time between the two instruments' measurements is accounted for using seasonal medians of expected behavior. Co-located measurements where the two MIGHTI imagers disagreed significantly were found, filtering out disagreements in measurement not likely to have a significant underlying ionospheric cause, although none were indicative of plasma bubble observations. These significantly differing measurements were most common shortly after dusk and in regions near the equator, especially between -30 to 70 degrees longitude. Simulations show the lack of definitive plasma bubble detections is likely due to MIGHTI's long image exposure time averaging out the effect of plasma bubbles as ICON orbits. More is now known about the potential for making comparative red-line airglow measurements between MIGHTI's imagers, and this information could be used in future work to explore larger-scale ionospheric structuring within the MIGHTI dataset.