For the first time, an international research team led by the Leibniz Institute for Tropospheric Research (TROPOS) has investigated atmospheric ice nucleating particles (INPs) in ice cores, which can provide insights on the type of cloud cover in the Arctic over the last 500 years.
For the first time, an international research team led by the Leibniz Institute for Tropospheric Research (TROPOS) has investigated atmospheric ice-nucleating particles (INPs) in ice cores, which can provide insights on the type of cloud cover in the Arctic over the last 500 years. These INPs play an important role in the formation of ice in clouds, and thus have a major influence on the climate. So far, however, there are only a few measurements that date back only a few decades. The new method could provide information about historical clouds from climate archives and thus close large gaps in knowledge in climate research.
The team from TROPOS, the University of Copenhagen, the University of Bern and the Paul Scherrer Institute writes in the journal Geophysical Research Letters that findings on variations in the concentrations of ice-nucleating particles in the atmosphere over centuries would help climate researchers to better understand future climate changes.
Climate archives are important for reconstructing the past climate and making statements about the development of the climate in the future. In Europe, the weather has only been observed and recorded regularly for around 300 years. For the time before and for locations without a weather station, however, research depends on conclusions from natural archives. Paleoclimate research uses a wide variety of natural archives such as tree rings, ice cores or sediments.
In recent decades, a number of methods have been developed and refined that use indirect indicators (climate proxies) to draw conclusions about climate factors such as temperature, precipitation, volcanic eruptions and solar activity. Clouds are responsible for precipitation, among other things, but they are very elusive and therefore difficult to study. But the number, type and extent of clouds and their ice content have a big influence on the radiation budget of the atmosphere, the temperature on the ground and precipitation, and information about parameters affecting clouds are hence important for climate reconstruction.
A method how to improve our knowledge about clouds and their role in climate history is now presented by an international research team from Germany, Denmark and Switzerland. According to them, the team has reconstructed the concentrations of ice-nucleating particles (INP) from ice cores for the first time. These measurements could be used to reconstruct cloud cover in the future.
“Ice formation in mixed-phase clouds is mainly caused by heterogeneous ice formation, i.e. INP are necessary to stimulate the freezing of supercooled cloud droplets. The number and type of these particles therefore influence precipitation, lifetime and radiation properties of the clouds. In the laboratory, we were able to show that two types of particles are particularly suitable for this purpose: Mineral dust from the soil as well as various biological particles such as bacteria, fungal spores or pollen,” explains Dr. Frank Stratmann, head of the Clouds Working Group at TROPOS.