Europe must invest in high value space technology
by Dr Johannes Bühl, postdoctoral researcher at the Leibniz Institute for Tropospheric
Research (TROPOS), Leipzig
Dr Johannes Bühl is a postdoctoral researcher at Leibnitz Institute for Tropospheric Research (TROPOS), Germany. Born in 1983, he studied physics with a main focus on optics at the Friedrich Schiller University Jena. He earned his PhD from University of Leipzig in 2015. In his current position as postdoctoral researcher he studies aerosol-cloud interaction with ground-based and space borne remote-sensing instruments.
A erosol, clouds and winds form inextricably intertwined components of the Earth’s atmosphere. They act on the Earth’s climate, both directly and indirectly, in ways that science is only just beginning to understand. But what is the significance of aerosols, clouds and winds for Europe’s future? Why do they matter?
Atmospheric exchange systems
The complex global interaction of aerosol, clouds and winds has many positive facets. Since ancient times, wind takes up mineral dust particles from the Sahara Desert and transports them over the Atlantic in a continuous lofted stream. When this stream arrives over the Amazon basin, turbulence and tropical thunderstorm clouds reach up and wash down the mineral dust. This constant supply of dust from the Sahara Desert naturally fertilises the Amazonian rain forest, the highly diverse biome that we know today (Baars et al, 2011; Yiu et al., 2015).
The connection between the Sahara Desert and the Amazon basin is one of the most obvious examples of how the atmosphere drives globally interconnected ecosystems. Europe is also engulfed in a couple of long-range atmospheric transport systems. What does this mean for the future? Aerosol is composed of tiny particles suspended in air with a large variety of physical and chemical properties that can have an enormous significance for life on Earth. However, aerosol also has its darker sides. Prominent examples most relevant to Europe include the 2010 Eyjafjallajökull volcanic eruption in Iceland which brought nearly all air traffic over Europe to a complete halt. Recent aerosol uptake by wild fires in the Chernobyl area (Evangeliou and Eckhardt, 2020) fall into the same category of complex scenarios in which aerosols, clouds and winds together pose a sudden threat.
The influence of a changing climate
On several occasions in Earth’s recent geological history, changes in aerosol emissions have affected incoming solar radiation in such a way that global temperatures went into oscillations with devastating effects. Aerosol and clouds will behave very differently in a future warmed climate. Wind systems, precipitation patterns and ocean currents will quickly adapt to new conditions and the composition of our atmosphere will be distinctly different from the one we know today. Deserts will shift, clouds will change in size and the distribution of precipitation will be modified. The highly interconnected physical processes in the atmosphere will need to be newly researched and understood.
Observational networks and satellites
Large-scale ground based observational networks must work together with spaceborne sensors in order to precisely measure and understand the current state of the atmosphere and its reaction to climate change. Such detailed observations of aerosol distribution, cloud properties and wind systems can be a starting point for mitigation of threats and solving scientific problems.
Europe is advancing in this direction and ACTRIS (European Aerosol, Clouds and Trace Gases Research Infrastructure) is in the process of combining, among others, the EARLINET (European Aerosol Research Lidar Network) and Cloudnet (European network for active remote-sensing observations of clouds) remote-sensing networks with ground-based observation stations within and outside the European continent. ACTRIS is therefore one cornerstone for Europe’s future resilience against short-term aerosol-related crises, a long-term response to climate change and a highly effective tool for solving other complex problems in atmospheric science.
Satellites – especially those equipped with active laser and radar sensors – are another critical component for enabling a global overview. Only such active remote-sensing instruments can deliver first-hand information about the spatial distribution and physical properties of atmospheric constituents. Missions like ADM-Aeolus (Atmospheric Dynamics Mission / satellite) and the upcoming EarthCARE (Earth, Aerosols and Radiation Explorer) satellite will together deliver the whole package of aerosol, cloud and wind observations, providing irreplaceable input to numerical models. Aeolus was a risky experiment, but it paid off and greatly extended the limits of what is possible in terms of global wind observations.
Extending the frontiers of knowledge
Extending Europe’s capabilities for atmospheric observations can only happen through a synergetic combination of ground-based, ship-borne and airborne field experiments and synergetic space-borne observations (Bühl et al., 2017).
The remote-sensing researchers of TROPOS are currently in the front line of contributions to this philosophy. Lidar (Light Identification Detection And Ranging – a laser instrument for probing the atmosphere) observations of aerosol were made close to the North Pole during the recent MOSAIC experiment on board the Polarstern research vessel (Engelmann et al., 2021). In addition, a measurement campaign at Punta Arenas, Chile, is ongoing and a new permanent ground-based observation station is being built on Cabo Verde island.
In the context of the EU Teaming project EXCELSIOR (Excellence Research Centre for Earth Surveillance and Space-Based Monitoring of the Environment /EU Teaming Project), the ERATOSTHENES Centre of Excellence (ECoE) for synergetic remote-sensing research is being founded at Limassol, Cyprus, with the help of a consortium of The National Observatory of Athens, The German Aerospace Research Center (DLR) and TROPOS. The ECoE will be a European outpost for atmospheric observations in a region where a complex mixture of aerosol and clouds poses great challenges for human health and the future climate.
Fast exploration and slow integration actions are equally important for the future and will enable better sensing of the physical processes and constituents of the atmosphere. This ability to see further will give us resilience against short-term atmospheric crises and critically important information for the sustained fight against climate change.
Baars, H., et al. (2011), Further evidence for significant smoke transport from Africa to Amazonia, Geophys. Res. Lett., 38, L20802, doi:10.1029/2011GL049200.
Bühl, J. et ad. (2017), Remote Sensing. Meteorological Monographs, 58, 10.1–10.21, https://doi.org/10.1175/AMSMONOGRAPHS-D-16-0015.1.
Engelmann, R. et al., (2020), UTLS wildfire smoke over the North Pole region, Arctic haze, and aerosol-cloud interaction during MOSAiC 2019/20: An introductory, Atmos. Chem. Phys. Discuss. [preprint], https://doi.org/10.5194/acp-2020-1271, in review.
Evangeliou, N., Eckhardt, S. (2020), Uncovering transport, deposition and impact of radionuclides released after the early spring 2020 wildfires in the Chernobyl Exclusion Zone. Sci Rep 10, 10655 https://doi.org/10.1038/s41598-020-67620-3.
Yu, H. et al., (2015), The fertilizing role of African dust in the Amazon rainforest: A first multiyear assessment based on data from Cloud?Aerosol Lidar and Infrared Pathfinder Satellite Observations. Geophys. Res. Lett., 42, 1984– 1991. doi: 10.1002/2015GL063040.