NASA - National Aeronautics and Space Administration

This was a Target of Opportunity flight aimed at sampling younger aerosol off the coast of Angola. The first priority was intensive in-situ aerosol sampling; if possible, the hope was to also get a radiation wall / square spiral out of it for SSFR/4STAR retrieval of spectral absorption and single scatter albedo. The flight plan, which we largely followed, was to transit south on 7E to 7S; then go east-bound to 10.5E. There, do the radiation wall along a north-south line ~7.0-7.6E. Then transit from 7S, 10.5E west to 7S, 5E and transit back to STM on 5E, with some in-situ sampling along the way if time/fuel permits. 
We encountered significant mid-level clouds on the south- and east- bound transit legs to the work area, requiring us to adjust alitude frequently to keep below the mid-level clouds (thereby allowing for HSRL retrievals). When we arrived at the work area there were still mid-level clouds, so we changed the usual order of the radiation wall and instead stepped down from high altitude, doing in-situ aerosol legs on the way down; then did the below-cloud, in-cloud and above-cloud legs before doing a square spiral back up to altitude. Unfortunately mid-level clouds interfered with the square spiral SSFR/4STAR measurements. We were able to do some more in-situ sampling on the leg back to STM on 5E.
This flight was most notable for the extremely high concentrations of aerosol on the 7-7.6S, 10.5E line at ~5-7,000' altitude. This was the most concentrated aerosol seen yet in ORACLES. In addition, based on preliminary in-flight observations, it was younger than other aerosol sampled during ORACLES.