COALA – Continuous Observations of Aerosol-cLoud interaction in Antarctica

• Applicant: Dr. Patric Seifert
• Subject Area: Atmospheric Science
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 463307613

The incomplete understanding of the interaction of aerosol particles with radiation, clouds, and precipitation is a key issue in atmospheric research. Detailed observations are required to capture the complex relationships between the involved processes. This is especially the case for the remote region of Antarctica, where ground-based vertically resolved long-term observations of aerosol, clouds and precipitation are scarce and satellite observations are prone to technical limitations. To fill the measurement gap with state-of-the-art observations, Leibniz Institute for Tropospheric Research (TROPOS) will deploy its OCEANET-Atmosphere platform at Neumayer III station (70.67°S, 8.27°W) between austral summer 2022/23 and end of austral summer 2023/24. OCEANET-Atmosphere comprises a set of active and passive remote-sensing equipment which is installed in an autonomous, polar-proven customized 20ft sea freight container that was just successfully deployed in the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC). The core instrumentation during the proposed project will be a multi-wavelength polarization and a Doppler lidar, 35-Ghz cloud radar, microwave radiometer, as well as 1-d and 2-d precipitation disdrometers. OCEANET is to date the only polar-prove single-container platform that can provide co-located observations of aerosol properties from multiwavelength lidar, of cloud particles and precipitation from radar and microwave radiometer, and of turbulent air motions in clouds from Doppler lidar and radar. The temporal and vertical resolution of the dataset will be on the order of 30 s (2 s for vertical-velocity observations) and 30 m, respectively. COALA is a 3-year project. A post-doctoral researcher will be in charge of the OCEANET-Atmosphere deployment at Neumayer III and the data analysis, with support of experts at TROPOS. The observations will be primarily used to address the key hypothesis of COALA, which is that aerosol from the Southern Ocean, southern-hemisphere midlatitudes and subtropics is transported to Antarctica where it influences the formation and evolution of clouds and precipitation. The work will be focused on (1) studying the origin, abundance and the characteristics of aerosol above Neumayer III station, (2) investigating the impact of surface- and boundary-layer-coupling effects on the characteristics and evolution of low-level clouds, (3) studying the contributions of dynamics (orographic waves), aerosol and meteorological conditions on the partitioning of the ice and liquid phase in clouds over Neumayer III, (4) studying the vertical structure of clouds and its relationship to precipitation formation, and (5) on the evaluation of regional contrasts in the properties of aerosols and clouds and the associated aerosol-cloud-interaction processes by putting the Neumayer III observations into context with existing datasets from Southern Chile, Cyprus, Germany and the Arctic.

• DFG Programme: Infrastructure Priority Programmes
• Subproject of: SPP 1158: Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas - with renewal proposal 2025 - 2030
• Co-Investigator: Dr. Ronny Engelmann