A near-real-time automatic detection system, based on the synergy of continuous measurements taken by a ceilometer and a photometer, has been implemented in order to detect lofted atmospheric aerosol layers and estimate the aerosol load. When heavy-loaded conditions are detected (defined by a significant deviation of the optical properties from a 10-year climatology), obtained for aerosol layers above 2500 m, an automatic alert is sent to scientists of the Romanian Lidar Network (ROLINET) to further monitor the event. The Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) back-trajectory calculations are used to establish the possible pollution source. The aerosol transport events are considered to be major when various optical properties provided by the photometer are found outside the climatological values. The aerosol types over the three years for all the events identified revealed that the contribution to the pollution was 31%, 9%, and 60% from marine, dust, and continental types. Considering only the ‘outside climatology limits’ events, the respective contribution was 15%, 12%, and 73% for marine, dust, and continental types, respectively.

Lidar measurements of 11 smoke layers recorded at Măgurele, Romania, in 2014, 2016, and 2017 are analyzed in conjunction with the vegetation type of the burned biomass area. For the identified aerosol pollution layers, the mean optical properties and the intensive parameters in the layers are computed. The origination of the smoke is estimated by the means of the HYSPLIT dispersion model, taking into account the location of the fires and the injection height for each fire. Consequently, for each fire location, the associated land cover type is acquired by satellite-derived land cover products. We explore the relationship between the measured intensive parameters of the smoke layers and the respective land cover of the burned area. The vegetation type for the cases we analyzed was either broadleaf crops or grasses/cereals. Overall, the intensive parameters are similar for the two types, which can be associated with the fact that both types belong to the broader group of agricultural crops. For the cases analyzed, the smoke travel time corresponding to the effective predominant vegetation type is up to 2.4 days.

This study investigates the impact of a thermal power plant site on air quality in Bucharest, Romania. It emphasizes the importance of accurate air pollutant inmission measurements in urban areas by utilizing mobile measurements of low-cost sensors, Copernicus’ Copernicus Atmosphere Monitoring Service (CAMS) and Copernicus Land Monitoring Service (CLMS), and satellite retrieval to better understand climate change drivers and their potential impact on near- surface concentrations and column densities of ${\mathrm{NO}}_2$, CO, and PM (particulate matter). It focuses the attention on the need of considering the placement of power plants in relation to metropolitan areas while making this assessment. The research highlights the limits of typical mesoscale air quality models in effectively capturing pollution dispersion and distribution using LUR (Land Use Regressions) retrievals. The authors investigate a variety of ways to better understand air pollution in metropolitan areas, including satellite observations, mobile measurements, and land use regression models. The study focuses largely on Bucharest, the capital of Romania, which has air pollution issues caused by vehicle traffic, industrial activity, heating systems, and power plants. The results indicate how the placement of a power plant may affects air quality in the nearby residential areas.

This paper presents a multi-parameter characterisation of the atmospheric composition at the RADO-Bucharest observatory, a regional WMO-GAW and ACTRIS facility in southeastern Europe, by anchoring recent observations within a multi-annual baseline (2015–2024). This paper utilises data from multi-wavelength active remote sensing, high-resolution near-surface speciation, and modelling to evaluate complex urban and transboundary processes across different aerosol and clouds regimes. The year 2025 was marked by an atmospheric perturbation, which was characterised by a quantifiable departure from the decadal climatology. Using Z-score analysis, this perturbation was identified as a seasonal decoupling: an atypical reversal in the vertical particle-size distribution occurred in the free troposphere between July and October, while a transition toward a high-absorption aerosol regime was recorded near the surface during the winter months. These shifts are quantified by a significant drop in the columnar Single Scattering Albedo and a systemic increase in high-troposphere Lidar ratios exceeding 70 ± 12 sr, indicating the presence of advected combustion products aloft. At the surface level, chemical speciation measurements recorded an overall increase in wintertime particulate mass concentrations alongside elevated levels of More-Oxidized Oxygenated Organic Aerosol (MOOOA) compared to previous years, reflecting an intensified accumulation of aged, processed emissions during the January–February period. Furthermore, this paper documents cloud vertical structure and phase occurrence, highlighting a persistent seasonal stratification. The application of unified inversion frameworks is demonstrated through case studies of smoke and mineral dust, applying the Generalized Retrieval of Atmosphere and Surface Properties (GRASP) algorithm to retrieve vertically distributed aerosol microphysics through lidar–photometer integration. Maintained under rigorous quality assurance protocols, these results demonstrate the value of continuous, multi-instrumental profiling to quantify transboundary perturbations and improve regional energy budget representations.

Smoke from the Canadian wildfires of August 2025 reached Cluj-Napoca, Romania, on 6–9 August as a thin layer at 5–8 km. We followed the plume from its source with the multi-angle polarimeters HARP2 and SPEXone and the OCI radiometer on NASA’s PACE and characterised it at the RADO-Cluj ACTRIS National Facility with a multiwavelength depolarisation lidar, a ceilometer, AERONET photometry, GRASP inversions, and HYSPLIT trajectories. Along the air mass trajectory, the HARP2 retrievals resolved the ageing of the smoke: an optical depth decaying from 0.9 to 0.2–0.3, a layer rising to 10 km and descending to 5 km, growth of the fine-mode radius, and a single-scattering albedo consistent with brown carbon loss. At the site, the lidar ratio and particle depolarisation ratio retrieved by HARP2 (52 sr, 0.042) agreed with the lidar’s derived lidar ratio and measured depolarisation (50 sr, 0.042), whereas the three satellite optical depths differed by 0.2 around an AERONET value of 0.1 and the NATALI typing networks returned three different classes. For this faint, aged plume, intensive polarimetric and vertical quantities could no longer be identified for the aerosol by its optical depth and Ångström exponent, which motivates testing an intensive-first pairing of satellite polarimetry with ground-based lidar on further episodes.