Aircraft campaign HALO (AC)³: Researchers investigate cloud movement in the Arctic

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The HALO research aircraft in the Arctic. Photo: Manfred Wendisch/University of
The HALO research aircraft in the Arctic. Photo: Manfred Wendisch/University of Leipzig

Special features of the Arctic climate, such as the strong reflection of the sun’s rays on the light-colored snow surface or the low position of the sun, intensify global warming in the Arctic. However, researchers are constantly faced with the challenge of mapping the climatic processes responsible for this in order to make reliable weather forecasts. Scientists from the HALO (AC) aircraft campaign have succeeded in precisely measuring the movement of air masses from and into the Arctic. This makes it possible to better understand the processes that drive climate change in the Arctic. Their research results have now been published in a paper by the European Geoscience Union.

"We want to make fundamental and groundbreaking progress in our understanding of Arctic amplification and improve the reliability of models for predicting the dramatic warming in the Arctic," says Manfred Wendisch, Director of the Institute of Meteorology at Leipzig University and lead author of the study. The large-scale, international HALO-(AC)³ research campaign to investigate changes in air masses in the Arctic, in which researchers from Leipzig University and several other research institutions are involved, began in mid-March 2022.

During the campaign, they used special aircraft to study the movement of air masses in and out of the Arctic via northward-directed moist and warm air intrusions and southward-directed marine cold air outbreaks. Two low-flying and one high-flying long-range research aircraft were flown in a joint formation whenever possible. We observed the air mass transports over areas of the open ocean, the sea ice edge zone and the central Arctic sea ice," reports Wendisch.

In March and April 2022, the HALO (AC) aircraft campaign took place over the Norwegian and Greenland Seas, the Fram Strait and the central Arctic Ocean. A novel observation strategy was used to track the changes in the air masses. This enabled the researchers to measure the moving air parcels twice along their transport path. "This allowed us to quantify the warming and cooling of the transported air masses for the first time. For example, we have shown that cold air escaping from the Arctic towards the south warms up to three degrees Celsius per hour on its way from the sea ice to the open sea. In addition, the humidity of the air increases on its way south," explains the meteorologist. The scientists also investigated the development of cloud properties along the air mass transport. This unprecedented data is currently being compared with calculations from the German weather forecast model.

Original title of the European Geoscience Union paper:

"Overview: quasi-Lagrangian observations of Arctic air mass transformations - introduction and initial results of the HALO-(AC)3 aircraft campaign" , doi.org/10.5194/acp-24-8865-2024

Dramatic warming of the Arctic and its global effects are being further researched
24.11.2023