Greek researchers Peristera Paschou and Dimitra Kouklaki recently joined international teams on an Atlantic mission to validate measurements from the European Space Agency (ESA) and Japan Aerospace Exploration Agency’s (JAXA) EarthCARE satellite, launched in May 2024.
The mission seeks to enhance understanding of atmospheric interactions between clouds, aerosols, and solar radiation, critical for improving climate and weather forecasts.
As part of EarthCARE’s calibration process, researchers collected comparative data through coordinated measurements on aircraft, ships, and ground stations. Paschou and Kouklaki represented the National Observatory of Athens in this intensive campaign, carried out under the ORCHESTRA program.
The program’s aim is to ensure EarthCARE’s readings reflect ground-based realities. Teams spread out to locations including Cape Verde and Barbados, gathering data as the satellite passed overhead.
Paschou, a PhD candidate and member of the National Observatory of Athens, spent six weeks aboard the research vessel Meteor, which sailed from Cape Verde to Barbados. Reflecting on the challenging journey, Paschou described the vessel’s route through the intertropical convergence zone, a low-pressure area notorious for strong storms, winds, and even tropical cyclones.
“It was intense, though thankfully, we didn’t encounter severe conditions that required redirection,” she told the Athens-Macedonian News Agency (AMNA).
Aboard the Meteor, Paschou operated a lidar instrument to monitor aerosols, clouds, and atmospheric factors like temperature and humidity.
This role demanded a daily regimen of testing and calibrating the lidar, vital for producing data comparable to the satellite’s own readings.
“The lidar system, shipped in a container from the Max Planck Institute in Hamburg, needed adjustments following its long journey. There were expected technical issues, but no insurmountable ones,” Paschou explained, adding that, “After the initial setup, we maintained daily checks to ensure optimal performance and data reliability.”
One of the mission’s highlights was the moment EarthCARE passed directly over the ship, with Paschou’s team capturing simultaneous readings alongside the satellite.
“We had to ensure continuous measurements without interruptions for accurate comparisons between the ship, the satellite, and an overflying research aircraft,” Paschou noted.
Meanwhile, high above the ship, Kouklaki’s team conducted parallel measurements on the German Aerospace Center’s (DLR) HALO aircraft, measuring sunlight, aerosols, and cloud dynamics. Kouklaki, another PhD student affiliated with the National Observatory of Athens, participated in the second leg of the mission, which moved its base from Cape Verde to Barbados.
“Our flight path varied with each mission, guided by weather forecasts, satellite trajectory, and the ship’s location,” she said.
One flight, a nine-hour journey from Barbados with six other scientists, gathered extensive data on atmospheric conditions, including aerosol concentrations, cloud composition, radiation levels, temperature, and pressure.
“Being my first experience in an aircraft-based experiment, it was an unforgettable challenge,” Kouklaki added.
“If something went wrong, quick, calm, and effective action was essential to avoid losing time or precious data. Thankfully, we faced mild weather.”
For Kouklaki, the moment the aircraft passed over the Meteor vessel was especially meaningful.
“It’s crucial to analyse remote sensing data from various angles, and having measurements from both the aircraft and ship improves resolution and data quality at different altitudes,” she said.
The Atlantic mission’s success lay in the simultaneous data collection by multiple scientific teams using advanced instruments at various altitudes and locations.
The collected data will advance scientific knowledge on aerosol-cloud interactions and their effects on weather and climate.
“We aim to deepen our understanding of how aerosols interact with clouds and solar radiation, which influences weather and climate predictions,” Paschou explained, adding that these measurements could also help refine forecasting models.
Vasilis Amoiridis, research director at the Institute for Astronomy, Astrophysics, Space Applications, and Remote Sensing, highlighted the unique atmospheric complexity of the Mediterranean, contrasting it with the Atlantic. He believes the Mediterranean will present EarthCARE with its greatest challenge, requiring satellite models to incorporate diverse climatic influences and pollutants for accurate forecasts.
“In the Atlantic, hurricanes may dominate, but its atmospheric composition is simpler than in the Mediterranean, where we encounter desert dust, marine aerosols, and wildfire smoke. The Mediterranean’s human activities, pollen, and microplastics also contribute to its atmospheric complexity, creating an intricate environment for EarthCARE to test.”
