Validation of EarthCARE lidar products using airborne measurements with the research aircraft HALO during the PERCUSION campaign

In May 2024 the ESA/JAXA satellite mission EarthCARE was launched into a low Earth orbit. The satellite combines a high spectral resolution lidar and a cloud radar with doppler capability as key instruments on one single platform. Additionally, it is equipped with a multi spectral imager and a broad band radiometer. This unique combination makes EarthCARE the most complex single satellite mission to study aerosol, clouds and precipitation. The successful use of these new data for science application needs a thorough validation of the measurements and the derived data products. A similar EarthCARE-like payload was implemented onboard the German research aircraft HALO (High Altitude and Long range).

This instrumentation was flown during PERCUSION (Persistent EarthCARE underflight studies of the ITCZ and organized convection) campaign. Within its scientific component this field experiment aimed to test factors assumed to control the organization of deep maritime convection, and to investigate the influence of convective organization on the larger-scale environment. The validation part of PERCUSION focused on an as close as possible spatial and temporal co-location of the airborne with the space-borne measurement, which can only be done using an aircraft.

Thus, we included an EarthCARE underpass within each research flight. HALO measurements were performed during the EarthCARE commissioning phase in August 2024 out of Sal, Cape Verde, and out of Barbados in September 2024. In addition, we performed pure validation flights out of Oberpfaffenhofen, Germany in November 2024 for the validation under atmospheric conditions that could not be captured in the two first campaign parts. Altogether, 33 EarthCARE underpasses were performed in different aerosol and cloud situations. Some of the flights were coordinated with in-situ measurements onboard other aircraft (e.g. the French ATR42), with shipborne measurements onboard the German research vessel METEOR, or with ground-based radar and lidar measurements at Mindelo (Cape Verde), Barbados, and the ACTRIS stations Antikythera, Leipzig, Lindenberg and Munich.

In our presentation we will give a short overview of the HALO PERCUSION field experiment. Selected EarthCARE underpasses will be used to exemplify the merits and limitations of the level 1 and some level 2 data products of the ATLID lidar onboard EarthCARE.