The international research campaign COMPEX (Clouds over complex environment) is kicking off with measurement flights over the Arctic and will investigate the properties of clouds over sea ice that cannot be detected by satellites. Since clouds play a central role in the climate of the polar region, the results will help scientists understand why this region is warming particularly rapidly compared to the rest of the world. They can also be used to map the underlying processes more accurately in future climate modelling. Dr Mario Mech from the University of Cologne’s Institute of Geophysics and Meteorology is leading the research campaign. Other collaboration partners include Leipzig University and the Alfred Wegener Institute for Polar and Marine Research.
The campaign is part of the Transregional Collaborative Research Centre (AC)³ "ArctiC Amplification" led by Leipzig University, which is investigating the rapid and intensified warming of the Arctic. The main objective of this research project is to unravel how clouds and sea ice influence energy fluxes in the Arctic atmosphere. Observations will concentrate on the complex structure of the marginal sea ice zone. In particular, the researchers are investigating the extent to which clouds and ice absorb and re-emit radiation, and how heat and moisture are transported between the surface and the atmosphere. The new measurements will expand existing data sets from the Arctic and, at the same time, enable an investigation of the limitations of satellite observations to better classify their measurements.
As with numerous previous Arctic expeditions within the framework of (AC)3, in which Dr Mario Mech was involved, the measurements are being carried out on board the Alfred Wegener Institute’s Polar 5 aircraft. The base for the aircraft operation will be Longyearbyen, Svalbard. In total, 80 flight hours are planned between 13 March and 15 April 2026. "Spring is the ideal time for the planned data collection, as sea ice coverage reaches its maximum during this period and is therefore easily accessible from Svalbard," says Dr Mario Mech. Professor Manfred Wendisch, spokesperson for (AC)³ at Leipzig University, adds: "For standard satellite observations, clouds over sea ice present a particular challenge because of the low contrast. Our measurement campaign aims to improve these methods and close existing observation gaps - albeit only in a small, spatially limited area."
The Polar 5 carries a range of instruments, including state-of-the-art radar systems for remote sensing of clouds and precipitation, radiometers for measuring upward and downward radiation, and sensors for quantifying vertical profiles of temperature, humidity, and wind. These instruments help us understand how much heat clouds and sea ice emit as radiation. The data collected during the campaign will contribute significantly to a more accurate description of key processes in the Arctic climate system.
