Aeronomy of Ice in the Mesosphere Solar Occultation for Ice Experiment

AIM’s mission is to study Polar Mesospheric Clouds (PMCs) that form about 83 km above the Earth’s surface in summer and mostly in the Polar Regions. AIM measures PMCs and the thermal, chemical, and dynamic environments in which they form to determine associations between these clouds and the meteorology of the polar mesosphere. Studying PMC variables has been proposed as a potential method for establishing indicators of global change.

SDL designed, fabricated, calibrated, and tested the Solar Occultation for Ice Experiment (SOFIE) aboard AIM. SOFIE combines IR/UV solar occultation, Gas Filter Correlation Radiometry (GFCR), and broadband Differential Absorption Radiometry (DAR) by solar image tracking to measure vertical profiles of particle extinction as well as temperature, water vapor, ozone, nitric oxide, and methane.

AIM has measured PMCs continuously with unprecedented precision since the mission was launched in 2007, compiling over a decade of data on critical aspects and properties of the clouds. It is now clear that the narrow altitude region where PMCs form harbors information on key processes that affect our entire atmosphere. AIM observations are providing a major tool for analyses to understand the combined effects of coupling by atmospheric dynamics from below, coupling by the meridional circulation across hemispheres, atmospheric temperature and H2O changes, changing solar conditions, and varying inputs of cosmic dust into our atmosphere.