The Trace Gases Remote Sensing Laboratory at RADO-Bucharest hosts a suite of ground-based instruments dedicated to the measurement of atmospheric trace gases and greenhouse gases. Its primary mission is to support satellite validation efforts for Earth Observation missions such as Sentinel-5P, OMI, and TropOMI, by providing high-quality column measurements of nitrogen dioxide (NO₂), ozone (O₃), carbon dioxide (CO₂), carbon monoxide (CO), and methane (CH₄). The laboratory operates in alignment with international calibration and validation standards through its participation in networks such as the Pandonia Global Network (PGN) and the Collaborative Carbon Column Observing Network (COCCON). The Pandora spectrometer system, operational at RADO since early 2016, provides continuous retrievals of total and tropospheric column NO₂ and total column O₃, using direct sun, direct moon, and sky radiance measurements. These datasets are fully compliant with ESA’s Validation Data Centre (EVDC) protocols and follow FAIR data principles. The Pandora observations have been extensively validated and are regularly used to assess the performance of satellite-borne instruments. In parallel, the laboratory includes a dual-channel Bruker EM27/SUN FTIR spectrometer, enabling retrievals of dry-air mole fractions (xCO₂, xCH₄, xCO) for long-term greenhouse gas monitoring and dedicated campaigns. These observations complement column data with in situ measurements from a PICARRO system, enhancing trace gas concentration profiling at the surface.

Supporting instrumentation includes an ozone lidar (OLI) system for vertical profiling of tropospheric ozone and a total radiation system to characterize the Earth-Sun radiation balance. The time series of trace gas measurements recorded at RADO-Bucharest reflect patterns typical of a peri-urban area, shaped by regional emission sources and transport processes. The laboratory plays an essential role in improving the understanding of atmospheric composition variability over southeastern Europe and contributes actively to international satellite validation campaigns and algorithm development.