Compact dual-wavelength depolarization lidar for aerosol characterization over the subtropical North Atlantic
Bibliographic record
Abstract
Abstract. We present a comprehensive characterization of the optical properties of various aerosol types based on data collected using a compact dual-wavelength depolarization elastic lidar (532 and 808 nm, CIMEL CE376). This study evaluates the vertical distribution and temporal evolution of aerosols observed in the subtropical North Atlantic region, covering Saharan dust, volcanic aerosols, and fresh and aged wildfire plumes. Measurements were conducted between August 2021 and August 2023, using a modified two-wavelength Klett inversion method to derive the aerosol backscatter and extinction coefficients from CE376 lidar measurements. To assess the performance of the CE376 system, an intercomparison campaign with an MPL-4B lidar (MPLNET) was conducted, with both systems were collocated at the Izaña Atmospheric Research Centre (Canary Islands, Spain). Both instruments depicted the vertical aerosol structure similarly. Discrepancies were primarily attributed to errors in determining the overlap function and depolarization calibration in each instrument, as well as the greater influence of solar background radiation on the CE376 system during daylight. The absolute difference in the volume depolarization ratio (δv) was 0.003, which decreased to 0.002 when only nighttime data were analyzed. The combination of the two channels of the CE376 provided valuable insights into particle linear depolarization (δP), extinction Ångström exponent (EAE (532/808)) and attenuated color ratio (ACR (808/532)). Fresh Saharan dust particles, characterized by large, non-spherical morphology and a well-mixed vertical layer, exhibited the lowest EAE (532/808), the highest ACR (808/532) and δP (532) >0.15. In contrast, smaller particles with quasi-homogeneous morphology were attributed to sulfate aerosols from the early stages of the Cumbre Vieja volcano eruption and aged Canadian wildfire plumes traveling across the Atlantic. These aerosols showed the lowest δP (0.03 for volcanic sulfate and 0.08 for aged wildfire aerosols) and the highest EAE (532/808) (1.5 and 1.2, respectively). Intermediate values of these retrieved parameters were associated with a heterogenous mixture of ash, soot and charred vegetation from fresh local forest wildfires. The retrieved properties underscore the suitability of the CE376 micro-lidar for continuous monitoring and characterization of the temporal and vertical distribution of atmospheric aerosols.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".