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APR-3 – Airborne Precipitation and Cloud Radar 3rd Gen

Friday, September 15, 2017

The Airborne Precipitation and Cloud Radar 3rd Gen (APR-3) successfully completed the 2017 deployment onboard the NASA P-3 for the ORACLES EV-S mission.

The Observations of Aerosols above Clouds and their Interactions Mission completed the second of three, one-month long deployments to probe how smoke particles from massive biomass burning in Africa influences cloud cover over the Atlantic.  Particles from this seasonal burning that are lofted into the mid-troposphere and transported westward over the southeast Atlantic interact with permanent stratocumulus "climate radiators," which are critical to the regional and global climate system.  The 2017 ORACLES deployment was based on Sao Tome with one suitcase deployment to Ascension Island.

APR-3 provides Doppler radar measurements of clouds and precipitation at 3 frequencies (Ku-, Ka- and W-band). APR-3 was developed at JPL under ESTO AITT’12 program by merging the Airborne Precipitation Radar 2nd Generation (APR-2, Ku and Ka band) with the Airborne Cloud Radar (ACR, W-band) and it is operated on the NASA P-3 for the ORACLES Mission by a joint JPL – University of Wisconsin team.  APR-3 acquired observations of the structure and dynamics of marine boundary layer clouds at unprecedented resolution in all of the successful science flights of ORACLES 2017. APR-3 experienced a significant hardware issue on the W-band computer during the outgoing transit flight, but the issue was promptly resolved by the field team as soon as the P-3 reached the base of operations in Sao Tome.  The affected subsystem was replaced by a full spare that had been pre-deployed via air shipment. The repairs did not cause any delay on the Mission flight schedule, and the new subsystem performed flawlessly for the rest of the campaign.

Compared to the ORACLES 2016 deployment, this year a significantly larger body of work was focused on a variety of cloud types, and this resulted in the acquisition of extremely intriguing observations that will be analyzed in the next two years. Again, compared to 2016, a larger fraction of the radar profiles includes echoes from the Ka- and Ku-band precipitation channels, and more modules were performed where radar observations were backed within 10s of minutes by in situ acquisitions of microphysical cloud and precipitation properties: these observations will be critical for the development of improved algorithms for current and future cloud and precipitation radar observations from space. By the same token, the synergy with HSRL (lidar), RSP (polarimeter) and radiometers was exploited to a greater extent in regards to cloud retrievals in this 2017 deployment. The processing code to produce preliminary geolocation and calibration for the basic L2 products (radar reflectivity and mean Doppler velocity) developed during the winter of 2016/17 was successfully exercised to produce quicklooks (when necessary also in quasi-real time in flight) and new experimental algorithms to provide more advanced analysis products requested by the Science Team was developed and successfully tested on in field data.

APR-3 also acquired data useful to GPM, ACE, and SWOT during the transatlantic legs between Wallops and Ascension Island. They include observation of cloud formations in the ITCZ possibly enhanced by the outflow of Hurricane Irma, and three frequency observations of marine cumulus congestus that are relevant to the recently concluded CPEX experiment as well as the planned CAMP2Ex campaign (Philippines, 2018).