The interplay of Clouds, Aerosols and Radiation above the Southern Ocean

Mission status: Scheduled.

Persons in Charge


Mira Pöhlker, Leibniz Institute for Tropospheric Research (TROPOS), Leipzig

Mission coordinator​


Contact point at DLR-FX for this mission:


HALO Deployment Base

Time Period

June – October 2025

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Project description

The Southern Ocean is one of the cloudiest region on earth with a high cloud radiative effect, with a high bias in atmospheric models. However, observations have shown that clouds over the Souther Ocean amplify the warming in this region.

It is also one of the view regions on earth with frequent pristine aerosol conditions where the effect of aerosols on clouds is biggest. The source of Cloud Condensation Nuclei in pristine oceanic regions is expected to be coupled to clouds and appears in the upper troposphere. The HALO-South mission is planned to take place in the Southern Ocean region mainly south-west and south of Wellington, New Zeeland, from August to September 2025. This will be at the end of the winter and the onset of the spring in the Souther 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 will be embedded in parallel intensive field activities including measurements on the research vessel Sonne and ground-based measurements from New Zeeland and will be supported by satellite investigations. HALO-South will provide pressing knowledge about the relation between aerosols and clouds in the southern hemisphere from cloud droplet and ice nucleation to the production of cloud and ice active particles partly triggered by increased radiation above clouds and cloud optical properties. These findings will be extrapolated to a larger scale using satellite data and global climate models. The campaign will greatly build on and continue past HALO campaigns with focus on either cloud and aerosol or gas and aerosol properties (CIRRUS-HL, ACRIDICON, CAFE-Pacific, CAFE-EU, CAFE-Brazil, CAFE-Pacific and will also overlap with EMeRGe-EU and EMeRGe-Asia). This campaign will cover the full cycle to investigate of aerosols throe clouds and the full cycle of clouds with a special focus on mix phase clouds, because this is where we expect that the important microphysical processes are happen influencing aerosols and radiation.



Scientific instruments and payload configuration

  • List of scientific instruments for the mission:

DescriptionPrincipal investigatorInstitution
SMART-Albedometerspectral radiance, spectral irradiance l= 350–2200 nmM. WendischLIM
BACARDIbroadband upward and downward irradiancesA. Giez & M. WendischDLR-IPA & LIM
HALO-SRspectral actinic flux densities 280-660 nmB. Bohn & M. WendischFZJ & LIM
CI-APiTOF MSH2SO4, HOMs, MSA, amines, clustersJ. CurtiusGUF
aerosol number and size distribution, including nucleation mode particles 1.5 nm to 5 μm
M. PöhlkerTROPOS
AEROSOL-Rackaerosol size distribution (10-30 nm), volatility of particles & optical propertiesD. SauerDLR-IPA
Refractive black carbon (rBC) particle mass and absorption coefficients at 3 wavelengths
C-ToF-AMSbulk aerosol composition (non-refractory)J. SchneiderMPIC
single particle chemical composition of aerosol / cloud residuals > 150 nm
J. SchneiderMPIC
cloud condensation nuclei (CCN) number concentration, reflective black carbon (BC) properties, aerosol impactor
Y. ChengMPIC
cloud particle residual number (> 10 nm), size distribution (60 – 1000 nm), and absorption coefficient, cloud water content
F. StratmannTROPOS
miniCCNfast scanning cloud condensation nuclei (CCN)F. StratmannTROPOS
high temperature Ice nucleating particle number concentration (INP)
F. StratmannTROPOS
PINEairINP and temperature spectrum at low temperatureJ. Curtius & O. MöhlerGUF & KIT
PCASP-100XAerosol size distribution, 0.12-3.5 μmD. SauerDLR-IPA
UHSAS-Adry particle size distribution 60-1000 nmD. SauerDLR-IPA
CAS-DPOLParticle size distribution, polarization, 0.6-50 μmC. VoigtJGU
CCP (CDP/CIP)particle size distribution, shape CDP 3-50 μm; CIP 15-960 μmC. VoigtJGU
PIPparticle size distribution, shape, 100-6400 μmC. VoigtJGU
BCPDbackscatter cloud probe with depolarization detectionC. VoigtJGU
PHIPSlight scattering, polarization, particle size distribution, 10-1000 μmM. SchnaiterKIT
SID-3particle size distribution, complexity, shape, 5-50 μmE. JärvinenKIT
MTPatmospheric dynamicsL. TomscheJGU
BAHAMASP, T, wind, humidity, TAS, position, alt.A. GiezDLR-FX
SHARCH2O mixing ratio (gas phase)A. GiezDLR-FX

Cabin and exterior configuration of HALO for the mission


HALO flights for this mission

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