Successful in-flight measurements of greenhouse gases over Brazil and Bolivia
- The CoMet 3.0 Tropics field measurement campaign has been successfully completed. The German research aircraft HALO conducted 18 research flights, 14 of which took off from Cuiabá in Brazil, totalling approximately 150 flight hours.
- The result is a unique dataset comprising measurements of greenhouse gases and associated parameters. This dataset will be worked with by many researchers in the coming years.
- The data provide reference values for validating satellite missions such as MERLIN, CO2M, Sentinel-5, GOSAT-2 and GOSAT-GW. They also enable the distinction between natural and anthropogenic sources of methane, contributing to the development of an MRV (monitoring, reporting and verification) system for greenhouse gas emissions.
From July 25 to September 6, 2026, the unique scientific instruments on board the German research aircraft HALO measured methane and carbon dioxide levels over South American wetlands. The flights took place over the Amazon and the Pantanal (Portuguese for ‘wetland’), as well as the Cerrado wet savannah. For the first time HALO’s flights went to Bolivia, over the wetlands of the Llanos de Moxos.
CoMet 3.0 Tropics was jointly led by the Max Planck Institute for Biogeochemistry in Jena, the DLR Institute of Atmospheric Physics and the University of Bremen as equal scientific partners, in close collaboration with the Brazilian National Institute for Space Research (INPE). The University of Heidelberg and numerous other German and Brazilian institutions contributed additional expertise and measurements. Around 120 researchers from Germany and Brazil participated in the campaign.
Christoph Gerbig, groupleader at the Max Planck Institute for Biogeochemistry and PI for in-situ observations, is still thrilled about the campaign. “The excellent collaboration between the participating institutions was what made this campaign particularly successful. The German teams brought together a variety of scientific approaches and requirements for the flight patterns – from our in-situ measurements to remote sensing – and managed to integrate them extremely well. Equally important was the close collaboration with scientists from many Brazilian institutions who contributed ground-based observations. Having participated in numerous field campaigns over more than 30 years, I consider CoMet 3.0 Tropics to be the best campaign I have experienced so far.”
Campaign highlights
During three flights over the Pantanal – one of the world’s largest inland wetlands, spanning an area roughly half the size of Germany – the temporal evolution of greenhouse gas emissions at the start of the dry season was recorded. Four flights took place over Bolivian territory – a first for HALO – including two flights that detected exceptionally high methane concentrations over the Llanos de Moxos wetlands.
Due to persistently high soil water levels, hardly any oxygen enters the soil. The soil microorganisms breaking down plant litter and soil organic material therefore operate in anaerobic conditions, which facilitates the generation of the greenhouse gas methane. Persistent high temperatures in tropical wetlands makes these a globally very important source of natural methane emissions although the magnitude of the flux remains insufficiently quantified.
There were also overflights of the 325-metre-high ATTO (Amazon Tall Tower Observatory) tower in the Amazon rainforest, a German-Brazilian project led by the Max Planck Institute for Biogeochemistry and the Brazilian INPA, where continuous measurements of meteorological, chemical and biological data, as well as greenhouse gas concentrations, have been taking place since 2015, and of the close-by Balbina Reservoir.
Further measurements were taken over the Amazon, its delta region and the Mamirauá wetlands. Here, too, surprisingly high methane concentrations were measured in the boundary layer close to the ground. The measurement programme was supplemented by overflights of pristine rainforest and by flying through several plumes of smoke from forest fires. Forest fires are also a significant source of greenhouse gases in the atmosphere.
Reference data for satellite missions and climate models
A key objective of the campaign was to validate existing satellite missions and prepare for future ones aimed at monitoring greenhouse gases. These include the Franco-German climate mission MERLIN, the Copernicus Sentinel Expansion mission CO2M, Sentinel-5, and, amongst others, the Japanese greenhouse gas satellites GOSAT-2 and GOSAT-GW. Airborne measurements provide spatially high-resolution reference data for this purpose, particularly in the tropics, where ground-based and satellite-based observations are limited due to difficult-to-access terrain and heavy cloud cover. At the same time, the campaign aims to help distinguish methane emissions from natural sources (such as tropical wetlands) from those from anthropogenic sources (such as agriculture, waste management, energy production and forest fires), and to reduce the uncertainty in global methane estimates. The data will be analysed using regional inverse models as well as climate-chemistry models and will ultimately contribute to reporting (MRV) under the United Nations Framework Convention on Climate Change.
Mission participants from our institute
The following members of the Max Planck Institute for Biogeochemistry (MPI-BGC) participated in the flight campaign, either partially overlapping or alternating:
Christoph Gerbig, groupleader at MPI-BGC, was the Principal Investigator for in situ observations, including a continuous laser spectroscopy system for CO2, CH4 and CO, as well as a flask sampling system for laboratory analysis of additional species, including isotopes.
Michał Gałkowski was responsible for flight planning regarding in-situ and instrument operation.
Santiago Botía, groupleader at MPI-BG, supported international collaborations and was also involved in the flight planning and instrument operation. He coordinated with the ground teams.
Doctoral researcher Nicolò De Santis was involved in operating the instruments and supporting flight planning.
As experienced technician Reimo Leppert monitored the instruments and took care of their maintenance ensuring their reliable performance.
Collaboration
CoMet 3.0 Tropics forms part of the scientific collaboration between Germany and Brazil. On the German side, participants included the DLR Institute of Atmospheric Physics, the Max Planck Institute for Biogeochemistry in Jena, and the Universities of Bremen, Heidelberg and Munich (LMUand TUM). Brazilian partners include, amongst others, the INPE, the Instituto de Pesquisas Energéticas e Nucleares (IPEN), the Universidade Federal de Mato Grosso (UFMT), the Universidade do Estado de Mato Grosso (UNEMAT), the Instituto Nacional de Pesquisas da Amazônia (INPA) and several research institutes at the Universität São Paulo (USP). Other partners from South America included the Universidad Mayor de San Andrés (Bolivia) and the GAW-Station Chacaltaya. As part of the ESA-funded BRACCIOLE project (Brazilian CO2 and CH4 and N2O Large-Scale Experiment), there was also international collaboration with ESA, which, as part of CoMet 3.0 Tropics, works closely with the complementary ESA project CarbonARA . For BRACCIOLE, the measurement flights were used in conjunction with the ATTO and Santarém ground stations to additionally record nitrous oxide (N2O) and emissions from forest fires, and to cross-check the data with satellite missions such as Copernicus Sentinel-5P, Sentinel-5 and the Japanese GOSAT missions.
CoMet 3.0 Tropics was funded by ESA, DLR and the Max Planck Society.
This press release is bases on the news message published by the DLR Institute of Atmospheric Physics.
