Overview
The Radiation Closure Experiments for EarthCARE Validation (RACE-ECV) is a scientific initiative led by the Physikalisch-Meteorologisches Observatorium Davos / World Radiation Center (PMOD/WRC), in collaboration with the University of Zurich (UZH). This project is part of the broader ACROSS campaign organized by ESA, which supports the calibration and validation (Cal/Val) of the EarthCARE satellite mission.
EarthCARE (Earth Clouds, Aerosols and Radiation Explorer) is an ESA satellite mission aiming to improve our understanding of how clouds and aerosols impact Earth’s radiation balance. RACE-ECV supports this mission by providing high-quality, ground-based measurements that validate satellite-derived aerosol and radiation products.
Scientific Objectives
Validation of EarthCARE Atmospheric ProductsUsing advanced ground-based remote sensing systems, the project validates EarthCARE satellite retrievals related to aerosol optical depth (AOD) and cloud optical properties.
Radiation Closure StudiesBy combining precise surface-based solar radiation measurements with radiative transfer models and satellite observations, the project performs detailed radiation closure experiments. These assess the accuracy of radiative flux estimates at the surface and top of atmosphere (TOA).
High-Quality Dataset for Collaborative ResearchThe project delivers validated datasets on aerosols and spectral solar irradiance for integration into international scientific efforts, including the EU CERTAINTY project on aerosol-cloud interactions.
Approach & Methodology
Experimental Campaigns
Two 6-week Intensive Observation Periods (IOPs) will be conducted in Spring 2025 and 2026 in the Eastern Mediterranean, primarily Crete and near Athens, Greece. The timing is coordinated with EarthCARE overpasses to maximize collocated data acquisition.
Instrumentation
Key instruments deployed by PMOD/WRC and UZH include:
Broadband Radiometers (shortwave and longwave)
Spectroradiometers for direct and diffuse irradiance
Precision Filter Radiometers (PFRs) for AOD retrievals
Sky cameras for cloud scene characterization
Radiative Transfer Models (RTMs) such as LibRadtran and Eradiate
All instruments undergo rigorous intercalibration at PMODWRC facilities to ensure data quality.
Satellite Synergy
Measurements are planned to coincide with EarthCARE overpasses. Ground-based data are compared against EarthCARE’s ATLID Lidar, Cloud Profiling Radar, Multispectral Imager (MSI), and Broadband Radiometer (BBR) data to assess accuracy.
Data Processing
Data from each campaign are:
Calibrated using PMODWRC reference systems
Processed into preliminary and final datasets
Shared via open-access databases for collaborative research
Expected Outcomes
Validated satellite products for aerosol optical depth, radiation fluxes, and limited cloud parameters
Robust closure models linking ground-based, airborne, and satellite data
Enhanced ground reference infrastructure for future ESA missions (e.g., CHIME, TRUTHS)
Scientific publications and open data shared with international research networks
Strategic Importance
RACE-ECV fills a critical gap in the EarthCARE validation program by addressing the need for high-accuracy surface radiation measurements. It positions Swiss institutions as central contributors to European Earth Observation science and strengthens long-term collaborations with ESA, WMO, and EU research infrastructures.
Project Timeline (2024–2026)
Phase 1: Preparation & Calibration (Nov 2024–Apr 2025)
Instrument intercalibration at PMODWRC
Development of campaign protocols
Phase 2: First Campaign & Preliminary Analysis (Apr–Jul 2025)
6-week field deployment in Greece
On-site data acquisition, initial QA/QC
Phase 3: In-depth Analysis & Model Validation (Jul 2025–Mar 2026)
Radiation closure simulations
EarthCARE aerosol/cloud product validation
Phase 4: Second Campaign & Final Evaluation (Apr–Jul 2026)
Second 6-week field deployment
Refinements based on lessons from the first campaign
Phase 5: Dissemination & Collaboration (Jul–Oct 2026)
Final publications and conference presentations
Cross-project links (e.g. CERTAINTY, ACTRIS, QA4EO)
RACE-ECV 