HALO airborne measurements; PERCUSION’s contribution to EarthCARE validation

In May 2024 the EarthCARE satellite mission EarthCARE was launched. For the first time, the satellite combines a high spectral resolution lidar and a cloud radar with doppler capability as key instruments on one single platform. In addition, it is equipped with a multi spectral imager and a broadband radiometer. This unique combination makes EarthCARE the most complex satellite mission to study aerosol, clouds, precipitation, and radiation. To fully use these new and advanced data for science applications, a careful validation of the measurements and data products is required. We have implemented an EarthCARE-like payload onboard the German research aircraft HALO (High Altitude and LOng range) to prepare and validate the EarthCARE data. This instrumentation was flown during PERCUSION (Persistent EarthCARE underflight studies of the ITCZ and organized convection) as a contribution to ORCESTRA (Organized Convection and EarthCARE Studies over the Tropical Atlantic).

ORCESTRA is a network of different campaigns conducted to better understand the organized tropical convection at the mesoscale, e.g. including the interaction of convective organization with tropical waves and air-sea interaction, and the impact of convective organization on the Earth’s climate and radiation budget. In addition, ORCESTRA helps to validate satellite remote sensing (especially EarthCARE). To achieve these objectives, ORCESTRA combines several sub-campaigns taking place on the Cape Verde Islands and Barbados in August and September 2024.

One of the campaigns within ORCESTRA is the PERCUSION campaign. PERCUSION aims to test factors hypothesized to influence the organization of deep maritime convection in the tropics and the influence of convective organization on its larger-scale environment. One focus of PERCUSION was to establish confidence in the EarthCARE measurements and products. For this purpose, we conducted one 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 flights out of Oberpfaffenhofen, Germany in November 2024 for validation of conditions that could not be captured in the two first campaign parts. Altogether, 33 EarthCARE underpasses were carried out in different aerosol and cloud situations. Some of the flights were coordinated with in-situ measurements onboard other aircrafts (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. Four underpasses under NASA’s PACE mission were also performed.

In our presentation we will give an overview of ORCESTRA with the main focus on PERCUSION. We will present the HALO PERCUSION measurements and will show first comparisons of HALO lidar and radar and EarthCARE lidar and radar measurements.