Seven joint flights were conducted between March 6th and 12th. This included two separate days of back-to-back flights. Five of the joint flights worked areas to the south of Virginia off of the Carolina coasts over the open ocean to be able to capitalize on having the low clouds we desire, having the least amount of high cloud interference (which affects remote sensing data quality), and also reduced the amount of icing that impacts sample collection on the HU-25 Falcon. The first joint flight on March 12 was special in that we conducted the first coordinated underflight during a satellite overpass. We specifically targeted the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and made sure to do this in a line of clouds without heavy interference from cirrus clouds. The scientific goal of that coordination is to characterize cloud morphology, as defined by cloud sizes, nearest neighbor distance, and fraction, and then to relate that information to cloud microphysical properties.
The last week has been very busy with seven more joint flights between 27 February and 2 March. This included two separate days of studying post-frontal cloud conditions with back-to-back flights. On those days we did a first flight to characterize vertically and spatially a large circle containing a dynamic cloud field. For the second flight on those days, the aircraft returned to the centerpoint of that circle and flew downwind to probe the evolution of the original cloud field in a Lagrangian fashion. A highlight of these flights was the UC12 launching 11 separate dropsondes around the circumference of the circle, which will be used to calculate quantities useful for comparison to and improvement of models. A particularly intriguing flight day was 29 February when the forecasts suggested we would be doing clear air sampling, but there actually were low clouds during the flight highlighting again how important ACTIVATE is to improve models’ ability to simulate marine boundary layer clouds.
The first ACTIVATE joint research flight took place on 14 February 2020 out of NASA Langley Research Center. The UC-12 and HU-25 Falcon flew in close coordination and watching the ACTIVATE sampling concept finally implemented was very exciting. To date we have conducted 3 joint flights, and 5 single flights with the HU-25 Falcon sampling a range of conditions including warm and mixed-phase clouds, solid cloud scenes and scattered cumulus clouds, post-frontal clouds, and clear air. The satellite data during some flights have shown that droplet concentrations are decaying with offshore distance, as confirmed by in-situ data. Early data show intriguing differences in microphysical data as the two aircraft transect through the gradients of cold and warm waters due to the presence of the Gulf Stream. In situ imaging data show the presence of a wide range of ice shapes including column-like needle structures. We are approaching an intensive stretch of fly-days this weekend again as the weather so far has been better for our science objectives than weekdays. On that note, our forecasting team has been phenomenal in putting the planes in the right places on the right days.