Happy Birthday, AIM! Five years old and still going strong! The spacecraft continues to perform nominally. We have several uploads awaiting bitlock and we have scheduled more TDRS relay satellite contacts. All other systems are healthy.
The SOFIE instrument continues to operate nominally. SOFIE observations have provided the first observational evidence that ice particles comprising PMCs contain small amounts of meteoric smoke. The Figure below demonstrates that the majority of SOFIE extinction ratios are not explained model predictions for PMC particles composed of pure ice, but can be explained by simulations considering a mixture of ice and meteoric smoke. The model results considered particles with an axial ratio of two, Gaussian size distributions with median radii from 2 to 80 nm (larger radii towards the left), and a meteoric smoke composition of Mg0.1Fe0.9O. The example shown is for SOFIE observations at the peak PMC altitude for the Southern PMC season of 2009-10, and similar results are found for other observations in both hemispheres. The SOFIE observations are used to simultaneously retrieve the PMC particle size and the volume content of smoke in ice. The results indicate that PMC particles contain 0.01 – 3% smoke by volume, and show that retrieved PMC particle sizes are smaller (~24%) when accounting for smoke compared to assuming pure ice.
CIPS continues to perform well, with no health issues. We successfully transition to northern hemisphere pointing in March, and are ready for the next season to begin in May. The figure below summarizes the CIPS retrievals of PMC ice water content for all seasons thus far observed, at a latitude of 85° N/S. We are introducing a new data product, level 3E. This product contains all CIPS observations within 100 km of specific ground-based observing stations, which are listed in the table below. This product is currently being tested, and will be available prior to the start of the NH 2012 season.