AEROCLOUD - How do aerosols and clouds affect the East Antarctic climate ?
AEROCLOUD is coordinated by the Catholic University of Leuven (Department of Earth and Environmental Sciences, Prof. Dr. Nicole Van Lipzig), in collaboration with partners Royal Meteorological Institute of Belgium and BISA - Belgian Space Aeronomy Institute (Michel Van Roozendael, Christian Hermans). AEROCLOUD is financed by the Belgian Science Policy Office (Belspo). AEROCLOUD started on 1 January 2015 for a duration of 4 years.
Project PI at RMI: Dr. Hugo De Backer
Project principal scientist at RMI: Dr. Alexander Mangold
Royal Meteorological Institute of Belgium
Ringlaan 3, Avenue Circulaire
BE-1180 Brussels, Belgium
Tel: 0032-23730593; email: alexander.mangold at meteo.be
Belgium has a long history of Antarctic exploration and scientific activities, dating back to 1897 and the first expeditions to Antarctica under the lead of Adrien de Gerlache. At the occasion of the 1958 International Geophysical Year, Belgium organised a new expedition to Antarctica and set up the Roi Baudouin base at Princess Ragnhild Kyst. This base remained in activity for more than 10 years and allowed scientists to carry out essential research and observations in climate and geophysical sciences.
At the occasion of the International Polar Year 2007, the Belgian government decided to build a new scientific summer station in Antarctica and assigned the International Polar Foundation to design and build this new base. The new Antarctic base was built during the Antarctic summers 2007/2008 and 2008/2009 and the first scientific activities started in January 2009. In the summer season 2009/2010 the station received the finishing works and a powerful satellite dish. The Princess Elisabeth station is situated north of the Sor Rondane Mountains in Dronning Maud Land, East Antarctica, on the small, granite Utsteinen ridge (71º57’S, 23º20’E, 1390 m asl).
Via the Belgian Science Policy Office (BELSPO), the Belgian federal government has been financing several research programmes at Princess Elisabeth station in Antarctica. During 2009-2012, a comprehensive meteorological-cloud-precipitation-aerosol observatory was established at Princess Elisabeth Station in Dronning Maud Land, East Antarctica by the promoters of the AEROCLOUD project (Prof. van Lipzig, KU Leuven, Dr. De Backer, RMI, Dr. Van Roozendael, BISA). The observatory was installed in the framework of the HYDRANT and BELATMOS projects, financed by the Belgian Science Policy. The instrumentation has been set up for continuous operation, including the non-manned winter period. AEROCLOUD further valorises the efforts made to establish this observatory.
Objectives of the AEROCLOUD project:
The water cycle, cloud microphysics and cloud-aerosol-radiation interactions are key components of the Antarctic climate system; clouds and aerosols play a significant role in the surface energy budget thus affecting the surface temperatures. It is hypothesized that changes in cloud amount or particle size have played a role in the major warming of the Antarctic winter troposphere. In addition, clouds are an important part of the hydrological cycle serving as the agents linking water vapour transport into Antarctica with precipitation. Because precipitation is the only source term in the mass balance of the Antarctic ice sheet, it is one of the key factors affecting sea level.
The remoteness and harsh conditions, inhibiting the deployment of instrumentation, limit the understanding of Antarctic cloud and aerosol processes. However, this is now changing with robust ground-based remote sensing instruments becoming available that can both vertically and temporally resolve the aerosol, cloud, precipitation and meteorological state. The first station, employing a comprehensive set of in-situ and remote sensing observations of clouds and aerosols is the Belgian Antarctic station Princess Elisabeth (PE) in Dronning Maud Land, East Antarctica. This is the only site that deploys a precipitation radar, which opens the avenue to obtain insight in quantitative precipitation amounts separately from the other components of the local Surface Mass Balance (SMB). Note that these other components are mainly redistribution of snow and sublimation.
The PE observatory opens the avenue to study the direct effect of clouds, precipitation and aerosols on the East Antarctic climate system. But it also enables a study on how aerosols affect the Antarctic climate indirectly: The “aerosol indirect effect” refers to the role of aerosols as cloud condensation and ice nuclei, thereby affecting clouds and precipitation. To study this effect, the one-moment schemes for representation of cloud microphysics, which are currently used in many Antarctic models, are unsuitable by design as these models do not relate the drop or ice particle size distribution directly to the aerosol distribution. Comprehensive double-moment cloud microphysics schemes do take into account a distribution of aerosols that activate at a given supersaturation, and in this way include the aerosol indirect effect. The regional climate model COSMO (COnsortium for Small-scale MOdelling) in its climate mode (COSMO model in Climate Mode, CCLM) does include such a double-moment scheme. In addition, it is a non-hydrostatic model with no scale approximations and applicable especially at the kilometre scale (in our case 2.8 km resolution). It is the first time that such a high-resolution climate model with a double-moment cloud scheme is applied to a region in Antarctica.
The objectives of AEROCLOUD are:
- Build up an extensive database on cloud, precipitation and aerosol properties derived from measurements performed at the Belgian station Princess Elisabeth in Dronning Maud Land, East Antarctica. This extensive database is referred to as the AEROCLOUD database;
- Evaluate and improve the CCLM regional climate model for Dronning Maud Land, using the AEROCLOUD database;
- Assess the role of aerosols and clouds in the East-Antarctic climate system, with focus on precipitation, surface energy balance and near-surface temperature, using the AEROCLOUD database and CCLM integrations;
- Improve the understanding of the relation between aerosols and clouds in East Antarctica, using the AEROCLOUD database and CCLM integrations;
- Valorise the results by scientific publications and workshops, easy access to an integrated database with all observations, open lectures to the general public and press contributions
RMI contribution to AEROCLOUD
Within AEROCLOUD, we aim to characterise comprehensively the physical and optical properties of the ambient aerosol at Utsteinen. From the combined measurements of the aerosol instruments, information on the aerosol type can be derived. Aerosol properties like mean size, number size distribution, presence of particle formation events, spectral dependencies of scattering, absorption and single scattering albedo will enable to classify the aerosol as fresh, locally formed, or aged, longe-range transported aerosol and to determine the presence and importance of dust, sea-salt, light-absorbing aerosols like soot, and rather scattering submicron particles (of which a large part is likely sulphate).
From the measurements, the radiative impact of the aerosol can be derived, in particular by studying the evolution of the single scattering albedo, and it will be possible to establish relations between physical and optical properties and aerosol type. By combining the aerosol observations with meteorological parameters and the calculation of air mass back trajectories, we will improve the understanding of the long-range transport of aerosol particles towards Antarctica and of the relative impact of rather continental or marine sources. A detailed description of the aerosol budget at PE station will be created, including seasonality, air mass origin and dependency on meteorology.
Furthermore, the aerosol measurements will be combined with the measurements of cloud and precipitation characteristics, order to study relationships between aerosol, cloud, and precipitation characteristics. These information will be used to evaluate and improve CCLM integrations. In addition, RMI will contribute to evaluated the regional climate model by the help of satellite data. Further, the regional Numerical Weather Prediction model ALARO will be run for the region of Dronning Maud Land and evaluated with data of the PE observatory.