From Fieldwork to the Literature: ORCESTRA Overview Paper Published
Convection in the tropical rain belt over the Atlantic is an impressive spectacle of nature: High clouds rise many kilometers above vast fields of low clouds. Depending on the conditions, they develop into locally intense thunderstorms or merge into extensive rain bands. Taken together, these processes shape the Intertropical Convergence Zone (ITCZ)—a large-scale structure that influences regional weather and the global climate. But how exactly does this interaction work—and how will it change under global warming?
To answer these questions, the Max Planck Institute for Meteorology (MPI-M) and its partner institutions deployed a large ensemble of scientific personnel and instruments to the region in August and September 2024 as part of the ORCESTRA field campaign. A recently published overview article now documents the coordination of this unique measurement campaign in the scientific literature.
Several terabytes of data
ORCESTRA was comprised of eight sub-campaigns and involved three research aircraft, two ground stations, and one research vessel. Using these platforms, the scientists conducted more than 2,000 atmospheric soundings, 90 oceanographic profiles, 56 research flights, and 45 drone flights. The field measurements were coordinated with the overpasses of the European Space Agency’s EarthCARE satellite, launched shortly beforehand. The extensive measurement program was supplemented by numerical experiments using the ICON climate model.
Credit: Stevens et al. 2026. DOI: 10.16993/tellus.4123
The new publication provides an overview of the campaign’s objectives, strategy, implementation, and collected datasets. “The goal of ORCESTRA was not to test a single hypothesis,” says MPI-M Director Bjorn Stevens, one of the initiators of ORCESTRA and lead author of the publication. “Rather, our aim was to combine different research questions within a common framework to better understand tropical deep convection and its interaction with the underlying ocean, across a range of space and time scales.”
Preliminary findings
The current publication also provides preliminary insights into the analysis of the ORCESTRA data. For instance, the researchers have already identified surprising differences in convection between the western and eastern Atlantic ITCZ. However, the atmospheric profiles in the upper, cooler part of the troposphere are strikingly similar across the different regions. The scientists are now further looking into these properties. In addition, they expect new insights regarding mid-level clouds. This cloud type appears to form both in situ and through transformation of other cloud types, as preliminary analyses confirm.
Finally, comparing the current measurement campaign with the GATE campaign, which took place in the same region 50 years earlier, when sea-surface temperatures were more than a degree cooler, provides insight into temporal differences and offers an on-site observation of the effect of global warming on the Atlantic ITCZ.
Original publication
Stevens, B., et al. (2026) ORCESTRA: Organized Convection and EarthCARE Studies over the Tropical Atlantic. Tellus, 79(1): 35–52. DOI: 10.16993/tellus.4123