New Temperature Observations in the Mesosphere and Lower Thermosphere fromthe MIGHTI Instrument on ICON

Abstract:

NASA’s Ionospheric Connection Explorer (ICON) satellite was launched on 10 October 2019 in order to study the complicated region of the Earth’s upper atmosphere that is affected by both the space environment from above and terrestrial processes from below. One of the four instruments on ICON is the Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI), which measures winds and temperatures on the limb between 12 S and 42 N in the mesosphere and lower thermosphere (MLT). Temperature measurements are made by imaging the O₂ A Band near 763 nm at three discrete wavelengths as well as a background at two wavelengths on either side of the A band. Temperatures at the tangent point are determined between 90-115 km by measuring the relative variation of A band emission at each altitude. The retrieval uses an onion peeling retrieval algorithm that removes contributions from overlying altitudes in order to isolate the emission originating from the tangent point. Here we present early temperature results from MIGHTI along with comparisons against empirical model results and existing datasets. Emphasis is placed on where the results deviate from our current understanding of temperatures in the MLT region.