TU Braunschweig and DLR successfully perform methane measurements at NordStream leaks Trailing probe investigates methane concentrations over the Baltic Sea

On Wednesday, the helicopter-borne trailing probe HELiPOD of Technische Universität Braunschweig performed methane measurements over the Baltic Sea in cooperation with the German Aerospace Center (DLR) and with the support of the United Nations Environment Programme. At the beginning of last week, several leaks were detected in the two gas pipelines Nord Stream 1 and 2, from which large quantities of natural gas are escaping. TU Braunschweig and DLR have now succeeded for the first time in measuring the methane concentrations and distribution in the vicinity of the pipeline leaks directly from the air.

At very short notice, the UN Agency for Environmental Protection and DLR decided to carry out measurements of the current concentration and distribution of methane over the Baltic Sea. The measurements were made possible by the scientific staff of TU Braunschweig, who were able to get their measuring equipment ready for use in such a short time. They used the HELiPOD helicopter-borne trailing probe, which is equipped with a wide range of equipment for atmospheric measurements. In close cooperation with DLR, the Institute of Flight Guidance (IFF) at TU Braunschweig launched two helicopter flights from the Polish coast near Kolberg.

Dr.-Ing. Falk Pätzold from the Institute of Flight Guidance participated in the measurements on the two flights with the HELiPOD, which was equipped with an additional methane instrument from the DLR Institute of Atmospheric Physics: “Before the flight, we didn’t know what to expect over the Baltic Sea. It was very thrilling to keep an eye on the methane concentration data in the helicopter, and then to actually measure elevated values near the leaks. The observed distribution of methane in the atmosphere partly deviated from simple model ideas and required flexible flight path adjustments during the measurement flights.” According to initial estimates by scientists, between 100 and 500 kilotonnes of methane could have flowed into the sea within a few days. It is still unclear what proportion of the methane remains in the ocean and how much has escaped into the atmosphere.

“Measurements at the highest scientific level”

The five-metre-long trailing probe HELiPOD is attached to a helicopter with a 25 m long rope. In the field, it can collect environmental data – without the interference of its own turbulence. The HELiPOD weighs about 300 kilograms and is packed with modern sensors for collecting various data. The instruments are mainly used for meteorological measurements as well as particles and various trace gases, such as methane measurements. The trailing probe was already successfully used in the MOSAIC expedition 2020 in the Arctic.

“The achievement of TU Braunschweig to offer measurements with their HELiPOD system within a few hours and at the highest scientific level is extraordinary. It is important that universities and research institutions in Lower Saxony maintain competences, as in this case, which they can call up and use at short notice for all of us,” says Björn Thümler, Lower Saxony’s Minister for Science and Culture.

“We were able to collect data at the known locations of the leaks with the methane instruments in the HELiPOD at low altitudes down to about 50 metres above sea level,” explains the head of the measurement campaign Dr Anke Roiger from the DLR Institute of Atmospheric Physics. “The detailed measurements of methane concentrations in the vicinity of the leaks will help us to characterise the dispersion of methane emissions from the different leaks and thus to assess the estimates of emission rates. These direct airborne flight-based measurements close the observational gap between the ground and satellite observations of recent days. A big thank you goes to the scientists involved from DLR and TU Braunschweig, the team from Technisches Hilfswerk (THW) who provided logistical support in preparing the measurements, the Polish helicopter company Helipoland who prepared and carried out the flights at short notice, and the support with weather forecasting and flight planning.”