Research Aircraft HALO

Clouds play a central role in Earth’s climate system—they can either warm or cool the planet, depending on their type, altitude, and thickness. But under what conditions do they act as a warming or cooling influence? To answer these and related questions, comprehensive, high-resolution atmospheric data are essential.

For this purpose, we rely on the research aircraft HALO (High Altitude and Long Range Research Aircraft), a globally unique platform for airborne atmospheric and Earth observation. With its exceptional range, capability to fly at extreme altitudes up to 15 km, and high payload capacity, HALO enables detailed, vertical profiling across vast geographical regions—from the lower troposphere to the upper troposphere and even into the stratosphere.

HALO marks a new era in airborne atmospheric research: for the first time, it allows systematic, long-range vertical measurements of water, water vapor, and ice throughout the atmosphere. Simultaneously, it captures detailed data on clouds, precipitation, and the aerosol particles that serve as nuclei for cloud droplet formation—critical insights into the complex interactions between atmosphere, clouds, and climate.

Onboard HALO is the HAMP (HALO Microwave Package), a state-of-the-art measurement system developed by our institute in collaboration with the University of Hamburg and the Institute of Atmospheric Physics at the German Aerospace Center (DLR). HAMP consists of a radar and a suite of microwave radiometers, enabling precise observations of precipitation, cloud structure, and atmospheric moisture. It is complemented by the WALES lidar from DLR and a range of passive sensors, providing additional data on aerosols and radiative processes.

HALO is a collaborative project of leading German environmental and climate research institutions. It was funded by the German Federal Ministry of Education and Research (BMBF), the Helmholtz Association (HGF), and the Max Planck Society (MPG). Ongoing operations are supported by the German Research Foundation (DFG), the Max Planck Society, Forschungszentrum Jülich (FZJ), Karlsruhe Institute of Technology (KIT), and the Leibniz Institute for Tropospheric Research (TROPOS). The German Aerospace Center (DLR) serves as both owner and operator of the aircraft.

Since late 2013, regular measurement campaigns have been conducted, in which our institute has played a key role—either as coordinator or as a technical and scientific partner. With HALO and its advanced instrumentation, we are advancing our understanding of clouds in the climate system—from local process studies to global climate modeling.