To close this gap, researchers from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), the Leibniz Institute for Tropospheric Research (TROPOS) and the Max Planck Institute for Chemistry (MPIC) have carried out the SANAT (Spatial distribution of ANtarctic Aerosol and Trace gases) flight campaign. The project focuses on the origin, composition and transport of aerosols in the Antarctic atmosphere that serve as seeds for cloud droplets and ice crystals, and it includes the first flight based aerosol measurements over Antarctica in 20 years and the first such measurements far into the interior of the continent.
Clouds form when water vapour condenses on tiny airborne particles known as aerosols. These particles can consist of sea salt, mineral dust, soot or other substances that provide surfaces for liquid droplets or ice crystals to develop. Over Antarctica, the atmosphere typically contains far fewer aerosols than mid latitude and tropical regions, so any changes in aerosol abundance or composition can strongly affect cloud formation and, in turn, how efficiently the region reflects solar radiation back into space.
The SANAT team is examining both natural and human influenced sources of aerosols, the conditions under which new particles emerge, and how aerosol properties evolve as they move through the atmosphere at different altitudes and across diverse surfaces such as open ocean, sea ice, ice shelves and the high Antarctic Plateau. According to AWI physicist Dr Zsofia Juranyi, the goal is to understand how these particles function as condensation nuclei and ice nuclei that ultimately determine whether liquid, mixed phase or ice clouds form above the frozen continent.
In January and February, the scientists collected extensive in situ data using the AWI research aircraft Polar 6. Operating from Germany Neumayer Station III, the team conducted ten measurement flights reaching as far south as the 80th parallel under challenging polar conditions. Previous flight campaigns two decades ago concentrated on coastal regions and mapped mainly the spatial distribution of aerosols, but did not probe the interior plateau or employ advanced instrumentation.
One of the key tools in SANAT is the T Bird towed probe, which is pulled behind the aircraft on a cable about 60 metres long. This instrument samples air independently of the aircraft wake and, together with the instruments mounted on Polar 6 and ground based systems at Neumayer Station III, provides a detailed picture of aerosol number, size distribution, chemical composition and small scale transport processes. At the same time, meteorological parameters such as air pressure, temperature and water vapour content are recorded to link aerosol behaviour with atmospheric structure.
The coordinated measurements from aircraft and ground have already delivered an initial surprise. Over the Antarctic interior, the researchers observed higher than expected aerosol concentrations along with unusual chemical signatures, indicating that particle sources and transport pathways into the plateau region may be more complex than previously assumed. These findings will be explored in detail over the coming months as the team evaluates the large data set obtained during the campaign.
Juranyi notes that Antarctica and the surrounding Southern Ocean are key components of the global climate system. They both respond to climate change and actively influence it by modulating heat, moisture and radiative exchanges between the surface and the atmosphere. With the unique SANAT observations, the consortium expects to refine weather forecasting and climate simulations by improving how models represent aerosol cloud interactions over polar regions and by better assessing how these processes may evolve under future climate conditions.
The research flights build on several earlier projects at Neumayer Station III that focused on clouds and their microphysical properties. Since 2019, cloud condensation nuclei and ice nucleating particles have been measured directly at the station trace observatory, providing continuous information on particles that can trigger droplet and ice formation. In 2023 and 2024, TROPOS deployed a dedicated container equipped with lidar and radar to monitor clouds above Neumayer Station III for a full year, adding remote sensing data on cloud structure and dynamics.
Together, the long term ground based observations and the new SANAT aircraft measurements are expanding the cloud related measurement programme at Neumayer Station III. By combining vertical profiles from the aircraft with in situ particle data and remote sensing time series, scientists aim to unravel the specific characteristics of Antarctic clouds, their sensitivity to aerosol changes and their role in regulating the polar radiation budget.
Related Links
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research
Beyond the Ice Age
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