Contrasting the stronger polluted and more continental marked Northern Hemisphere (NH) with the more pristine and more maritime pronounced Southern Hemisphere (SH) provides a natural laboratory to investigate and to better understand the direct and indirect (via the modification of clouds) role of aerosols in the climate system. We are proposing a coordinated joint HALO-mission to obtain in-situ observations and remote sensing of aerosol and cloud microphysical properties in cold super-liquid and mixed-phase clouds, where the differences in ice nucleating particles (INP) show the largest effect on the freezing temperatures.

Hypothesis: Aerosol sources, transport, processing, and aerosol particle physical and chemical properties resulting from aerosol-cloud-interaction (ACI) differ in the NH and the SH, which results in differences in super-cooled and mixed phase cloud compositional, microphysical, dynamic and radiative properties.

HALO observations and leads:

·       In-situ measured aerosol, CCN, BC abundance and properties (TROPOS)

·       In-situ measured INP and CPR properties (TROPOS and Uni Frankfurt/KIT)

·       In-situ measured liquid, mixed-phase and ice cloud microphysical properties (DLR and KIT)

·       Cloud radiative properties and cloud top radiative cooling (LIM)

·       Remote sensing (ground-based, HALO and satellite) of aerosol and cloud microphysical properties (DLR and TROPOS)

·       In-situ measurements of water vapor and tracers (DLR)

The HALO-South mission will be synchronized with DACAPO-goSouth. Furthermore, it is planned to carry out accompanying atmospheric measurements in the marine environment with the German research vessel Sonne.

Platform: HALO aircraft

Location: New Zealand region in combination with NIWA and TROPOS ground-based remote sensing. Additional ship observations proposed. 

Timing: October 2025


  • Andreas Macke (macke<@>tropos.de)
  • Mira Pöhlker (poehlker<@>tropos.de)