HALO-South

Sept/Oct 2025, Christchurch, New Zealand

The Southern Ocean is one of the cloudiest regions on earth, thus it has a high cloud radiative effect, but there is still a high bias in atmospheric models. Observations have shown that clouds over the Southern Ocean amplify the warming in this region. It is also one of the few regions on earth with frequent pristine aerosol conditions where the effect of aerosols on clouds is biggest. The HALO-South mission takes place in the Southern Ocean region mainly south-west and south of Christchurch, New Zeeland, from September to October 2025. This is at the end of the winter and the onset of the spring in the Southern Ocean.

The HALO aircraft is equipped with a unique set of instrumentation to investigate aerosol and cloud cycles and its effect on radiative properties of the clouds. The campaign is embedded in parallel intensive field activities including ground-based measurements from New Zeeland and will be supported by satellite investigations. HALO-South will provide knowledge about the relation between aerosols and clouds in the southern hemisphere, from cloud droplet and ice formation to the production of cloud condensation nuclei (CCN) and ice nucleting particles (INP), partly triggered by increased radiation above clouds, due to the clouds‘ optical properties. The campaign will build on and continue past HALO campaigns with focus on either cloud and aerosol or gas and aerosol properties (CIRRUS-HL, ACRIDICON-CHUVA, CAFE-Pacific, CAFE-EU, CAFE-Brazil, CAFE-Pacific) and will also overlap with EMeRGe-EU and EMeRGe-Asia. 

Instruments of our group:

C-ToF-AMS, ALABAMA

Involved staff of research group Schneider:

T. Böttger, H.-C. Clemen, A. Hartmann, P. Joppe, K. Kaiser, P. Schuhmann, J. Schneider

Collaboration with:

Leibniz Institute for Tropospheric Research (TROPOS)
Leipzig University, Leipzig Institute for Meteorology (LIM)
Johannes Gutenberg University Mainz (JGU)
Goethe University Frankfurt (GUF)
Karlsruhe Institute of Technology (KIT)
German Aerospace Center, Institute of Atmospheric Physics (DLR-IPA)
Forschungszentrum Jülich (FZ Jülich)