Seminar

Abstract

Worldwide regulations to control the COVID-19 pandemic caused significant reductions in ground and airborne transportation in spring 2020. This unprecedented situation provided the unique opportunity to directly measure the less perturbed atmosphere, notably near the tropopause, and derive the effects of anthropogenic emission changes on atmospheric composition and climate.

The BLUESKY mission employed the high-altitude, long-range research aircraft HALO and the DLR Falcon together with satellite observations and models to study atmospheric composition changes. From 16 May to 9 June 2020, the two research aircraft performed 20 flights over Europe and the North Atlantic. Profiles of trace species were measured with an advanced in-situ trace gas, aerosol and cloud payload from the boundary layer to 14 km altitude. I will present an overview and selected highlights of the campaign.

Continental aerosol profiles show significant reductions in aerosol mass in the boundary layer and lower organic aerosol mass fractions in the free troposphere. The reduced aerosol optical thickness above Germany has also been detected by MODIS and leads to the observed “blue sky” in the BLUESKY lockdown period 2020.

A specific focus was the investigation of trace species and cirrus changes caused by up to 90% reductions in air traffic. We find reductions in reactive nitrogen species and fine mode aerosol in the UTLS at various levels compared to EMAC model results and to CARIBIC data in May/June 2005 to 2019. In addition, we derive reductions in contrail and cirrus cover using passive and active remote sensing from satellite combined with cloud modeling.

The comprehensive data set acquired during the 2020 lockdown period allows better understanding and constraining the anthropogenic influence on the composition of the atmosphere and its impacts on air quality and climate.

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After studying applied mathematics and physics at the Oxford Brookes University, Oxford (UK), Christiane Voigt received her PhD in 2000 from the Max Planck Institute for Nuclear Physics, where she developed a balloon-borne mass spectrometer with which she measured the composition of polar stratospheric clouds. As a postdoctoral fellow with the Federal Institute of Technology in Zurich, Switzerland, she studied ice nucleation using numerical simulations. She joined the German Aerospace Center (DLR) in 2002, where she participated over the following four years in numerous aircraft field campaigns (EUPLEX, SCOUT, TROCCINOX, AMMA, CIRRUSIII, ASTAR), with a focus on cloud chemistry measurements. Dr. Voigt was appointed assistant professor in experimental meteorology at the Johannes Gutenberg University in Mainz, Germany, in 2009. Since 2014 she is the head of the Cloud Physics Group at the German Aerospace Center (DLR), and since 2015 an associate professor of experimental meteorology at the Johannes Gutenberg University in Mainz.