Project Details
Projekt
Measurement of Aerosol and Clouds and their Interactions over the pristine Southern Ocean – ACI-SO
Applicants
Dr. Daniel Sauer; Professorin Dr. Christiane Voigt
Subject Area
Atmospheric Science
Term
since 2024
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 522359172
The Southern Ocean is a particularly cloudy region on earth and exhibits the strongest biases in near-surface temperatures simulated by current global climate models. A large aircraft and ship-based research experiment has recently augmented the scarce experimental cloud data set over the Southern Ocean in autumn. This project will measure the aerosol and cloud microphysical properties over the Southern Ocean in spring. We will relate the southern mid-latitude aerosol and cloud measurements in one of the most pristine environments on earth to previous observations in more polluted northern mid-latitudes. The novel experimental in-situ data set of aerosol and cloud microphysical properties will be used to investigate liquid cloud formation and ice nucleation. Within this project, airborne in-situ data on liquid low-level, mixed phase and cirrus clouds will be measured on HALO in profiles and transects from New Zealand using a suite of wing-mounted cloud probes. Particle number concentration, size distributions from 0.6 µm to 6 mm, liquid and ice water contents will be derived by one PhD student from the combination of the Cloud and Aerosol Spectrometer CAS-DPOL, the Cloud Combination Probe CCP and the Precipitation Imaging Probe PIP. To assess aerosol influences on clouds, accompanying aerosol microphysical data such as particle number concentrations and size distributions will be measured by condensation particle counters, a scanning mobility particle sizer SMPS, a single particle soot photometer SP2xr and the wing-mounted aerosol instruments UHSAS and PCASP by a second PhD student. Cloud condensation nuclei number concentrations will be related to updraft to investigate their impact on cloud droplet number concentrations in pristine Southern Ocean conditions. Besides liquid cloud formation, this project will investigate ice nucleation in mixed-phase and cirrus clouds. Distributions of ice microphysical properties in frontal systems and convection over the pristine Southern Ocean will be compared the observations in northern mid-latitudes (e.g. from the campaigns ML-CIRRUS and CIRRUS-HL). The project will deliver a comprehensive data set of cloud and aerosol microphysical properties from an environment as close to pre-industrial conditions as possible. The cloud and aerosol observations from the Southern Ocean help to evaluate and improve the cloud parameterizations of the global climate models EMAC and NCAR-CAM in a region on earth where biases of modelled surface temperatures are largest.
DFG Programme
Infrastructure Priority Programmes
