the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 04 Aug 2026
Measurement Report: Long-Term Aerosol Profiling over Albania and the Adriatic Sea with Satellite and Ground-Based Lidars
Abstract. Vertically resolved aerosol characterization is crucial for assessing the impact of aerosols on radiation, cloud formation, and climate. Atmospheric aerosol particles exhibit significant spatial and temporal variability, making long–term observations essential for understanding these variations and developing an aerosol climatology. We conducted, for the first time, long–term lidar measurements in Albania during 2022–2023 using a ground–based Raman lidar. In this study, we evaluate aerosol extinction profiles, and mass concentration profiles using 15 years of Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) data and one year of ground–based Raman lidar measurements. We present seasonal patterns of total, dust, and non-dust contributions. Additionally, we analyze monthly AOD variations over a 15–year period from CALIPSO and a one–year period from POLLY (POrtabLe Lidar sYstem). Along with aerosol climatology, the air mass cluster backward trajectories by means of HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory) are shown as seasonally means for a 10–year period. The maximum extinction coefficient retrieved by CALIPSO in the near-surface layer ranges from 80 to 100 Mm−1. In comparison, POLLY observations at 300 m altitude indicate maximum extinction values between 75 and 125 Mm−1. The maximum height of the aerosol layer is detected between 8 and 10 km. Wildfire smoke layers were identified up to 10 km height during the summer season. Strong Saharan dust outbreaks, with mass concentrations up to 300 µg m−3, and moderate events, with concentrations around 100 µg m−3, are presented through two case studies and analyzed in detail. The highest AOD values are observed during summer, specifically in August, reaching approximately 0.26 for CALIPSO and 0.19 for POLLY. In contrast, the lowest values occur in winter. For POLLY, the minimum AOD is recorded in December at 0.053, while for CALIOP, the lowest values are around 0.1, observed in December and January. HYSPLIT backward trajectories cluster analysis indicates regional aerosol transport primarily from the Balkans and Italy, along with long-range transport from Western Europe and North America.
Status: open (until 15 Oct 2026)
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RC1: 'Comment on egusphere-2026-4264', Anonymous Referee #1, 17 Sep 2026
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The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2026/egusphere-2026-4264/egusphere-2026-4264-RC1-supplement.pdfReplyCitation: https://doi.org/
10.5194/egusphere-2026-4264-RC1 -
RC2: 'Comment on egusphere-2026-4264', Anonymous Referee #2, 30 Sep 2026
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General comments
The manuscript “Long-Term Aerosol Profiling over Albania and the Adriatic Sea with Satellite and Ground-Based Lidars” presents aerosol observations in a country where vertically resolved measurements are scarce. The study combines long-term CALIOP Level-3 aerosol observations, one year of ground-based POLLY Raman-lidar measurements in Tirana, and a multi-year HYSPLIT backward-trajectory analysis. In addition, two aerosol-event case studies are presented. The ground-based measurements are particularly valuable, as they provide one of the first extended lidar datasets over Albania and thus contribute useful information on aerosol vertical structure, Saharan dust transport, pollution, and elevated smoke layers in the western Balkan region. The paper is appropriate for ACP but certain issues outlined below should be considered before acceptance
Major comments:
One main concern is the interpretation of the comparison between CALIOP and POLLY data. The CALIOP dataset represents a multi-year average over a relatively large 5° × 2° region, whereas POLLY represents a single location and approximately one year of observations during a completely different period. These datasets are therefore complementary, but they are not directly comparable in the sense of a validation exercise or an assessment of temporal change, as it used in the study. Several statements in the Results and Conclusions appear to interpret differences between them as actual temporal changes in aerosol conditions, which is not sufficiently supported by the present analysis.
A second important issue is that the paper does not put the measurements and results in a broader context regarding the area. There are numerous EARLINET stations in the region and an appropriate discussion of the results should added.
Specific comments
- Nature of the CALIOP–POLLY comparison. This is, in my opinion, the central issue of the manuscript. CALIOP represents a long-term regional climatology, whereas POLLY provides a one-year record at a single site. In addition, the periods do not overlap. The authors themselves note the different spatial averaging and the different dust conditions during the periods considered. The comparison should therefore be presented primarily as a comparison between a regional long-term climatological context and the seasonal characteristics observed during the 2022–2023 Tirana campaign, rather than as a direct quantitative intercomparison
- The manuscript repeatedly describes the 2022–2023 POLLY observations as “long-term” and refers to an aerosol climatology derived from the one-year dataset. A one-year dataset is extremely useful for characterizing a complete seasonal cycle, but it cannot normally be considered a climatology
- CALIOP time period is inconsistent throughout the paper. The Methods and Table 2 indicate June 2006–December 2021, whereas the captions of Figures 4 and 5 refer to June 2006–December 2022. Elsewhere the text refers to “15 years”, while Figure 3 refers to a “16-year dataset”. The exact period used in every calculation needs to be checked and stated consistently. I suggest giving the exact start/end dates rather than alternating between “15 years” and “16 years”.
- The conclusion that pollution was almost constant from 2006 to 2023 is not justified. Section 3.3 states that good agreement between CALIOP and POLLY indicates that “the aerosol pollution was obviously almost constant over the 2006–2023 time period”. This conclusion cannot be drawn from two datasets with different spatial representativeness, sampling characteristics, retrieval assumptions, and non-overlapping time periods. I strongly recommend removing this statement.
- AOD differences need a more cautious interpretation. CALIOP AOD and POLLY AOD differ not only because of aerosol conditions but also because of spatial sampling, temporal sampling, cloud filtering, overlap treatment, and the different observation periods. I do not think the statement that the Balkans experienced “significantly more intense Saharan dust outbreaks” during 2006–2021 than during 2022–2023 can be demonstrated from this comparison alone.
- Backward trajectories indicate transport pathways, not aerosol sources. The text frequently moves from trajectory frequencies to statements about aerosol source contributions. For example, the manuscript concludes that at 7.5 km “the aerosol originates mainly from North America (around 50%)”. However, the ~50% value shown in Figure 6 refers to the fraction of trajectories assigned to a particular trajectory cluster, not the fraction of aerosol mass originating in North America.
- The two case studies would benefit from event-specific transport evidence. The optical properties shown in Figures 7 and 8 provide good evidence for the identification of dust and smoke aerosol types. However, statements assigning the smoke to specific geographic fire regions would be much stronger if accompanied by event-specific HYSPLIT trajectories and, ideally, satellite fire/smoke information. The seasonal HYSPLIT climatology cannot establish the origin of an individual smoke layer.
- Several numerical ranges are internally inconsistent. For example, the Abstract gives a minimum POLLY AOD of 0.053, the Results report an overall POLLY range of approximately 0.005–0.20, and the Conclusions report 0.001–0.19. These may refer to different altitude intervals versus total-column values, but this is not made clear. Similarly, maximum extinction values differ among the Abstract, Results, and Conclusions. All headline numbers should be checked and harmonized, with the altitude range and aerosol component stated where necessary.
Citation: https://doi.org/10.5194/egusphere-2026-4264-RC2
Data sets
POLLY dataset Tropos https://polly.tropos.de/calendar/location/46
Calipso data Earthdata Search https://search.earthdata.nasa.gov/search
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