Current climate models misrepresent cloud formation over the Southern Ocean causing mismatches between models and satellite observations. These errors are important because too much sunlight reaches the ocean surface in simulations, leading to overestimates of ocean temperature by nearly 2oC in many models, making the Southern Hemisphere (SH) jet stream and accompanying storm tracks notoriously difficult to model accurately. This is a critical issue for regional climate forecasting over Aotearoa-New Zealand significantly reducing our ability to confidently model climate change in our own backyard.
Can we improve global and regional climate projections by improving understanding of the effect of marine aerosol particles on cloud formation?
One possible solution is to represent the large numbers of tiny aerosol particles generated from biological and physical processes in the ocean, which are lifted into the atmosphere acting as cloud condensation nuclei, forming cloud droplets. The mechanism is reasonably well understood but its magnitude and subsequent dynamics are largely unknown. Unfortunately, there are very few Southern Hemisphere measurements to derive these model improvements, though relevant theory suggests that these processes are important.
The Go South project brings together experts in ocean-aerosol-cloud-radiation interactions from Germany and New Zealand to carry out land and air measurements on New Zealand’s coastline. We will measure aerosol particles from formation at sea level and follow them as they rise to form clouds and associated cloud dynamics. We will be amongst the first to quantify this effect, thus enabling more accurate prediction of the impact of aerosol-cloud interactions on regional and global climate.
The Go South pilot project took place in November 2022 at Te Waewae Bay in Southland, with collaborators from The Leibniz Institute for Tropospheric Research (TROPOS), The university of Hannover, Canterbury University, the University of Auckland and NIWA (now The Air Quality Collective). It was able to demonstrate the feasibility of such measurements (Figures 1 and 2)
Go South 2 – 2025 – 2026
Partners from TROPOS, Canterbury University, The Air Quality Collective and Metservice are now planning a large integrated Southern Ocean-Aerosol-Cloud interaction programme that will bring together ship- and airborne measurements with long tern ground based observations.
Go South 2 – May 2025- June 2026
LACROS DACAPO – NZ
The Leipzig Aerosol and Cloud Remote Observations System (LACROS) platform will be deployed at the Metservice station near Invercargill Airport from May 2025- June 2026. It will measure,
- Ground based remote sensing of cloud microphysical properties of clouds and aerosol
- In-situ ground based measurements of aerosol chemistry and physics
HALO South – August to September 2025
The German Aerospace Centre (DLR) research aircraft “High Altitude Long-Range Observatory” (HALO) will be deployed out of Christchurch during August and September 2025 to make in-cloud measurements of cloud and aerosol properties to investigate “The interplay of Clouds, Aerosols and Radiation above the Southern Ocean”
It will investigate the interactions of gas phase chemistry, aerosol nucleation and growth, cloud formation and development, and radiative impacts in the southern hemisphere North and South of New Zealand
ACAROA (R/V SONNE) January – February 2026
The German research vessel Sonne will visit Aotearoa and the Southern Ocean in early 2026 for the “Atmospheric Clouds, Aerosol, and Radiation in the Southern Ocean around Aotearoa” (ACAROA) project, which will Investigate the interplay between ocean, aerosols and clouds in a complex Southern Hemisphere Ocean/atmosphere/land system –Tasman sea, Southern Ocean, South Pacific
These three integrated projects will provide one of the first detailed pictures of southern hemisphere ocean-aerosol-cloud interactions, which will improve climate modelling in the southern hemisphere. Due to a lack of existing data, climate models are tuned with northern hemisphere data, which can be substantially different from southern hemisphere conditions and contributes to the known errors in model estimates of cloud formation over Aotearoa.
