Black carbon concentrations and modeled smoke deposition fluxes to the bare ice dark zone of the Greenland Ice Sheet
Bibliographic record
Abstract
Abstract. Ice-albedo feedbacks in the ablation region of the Greenland Ice Sheet (GrIS) are difficult to constrain and model due in part to our limited understanding of the seasonal evolution of the bare-ice region. To help fill observational gaps, 13 surface samples were collected on the GrIS across the 2014 summer melt season from patches of snow that were visibly light, medium, and dark colored. These samples were analyzed for their refractory black carbon (rBC) concentrations and size distributions with a Single Particle Soot Photometer coupled to a characterized nebulizer. We present a size distribution of rBC in fresh snow on the GrIS, as well as from surface hoar in the bare ice dark zone of the GrIS. The size distributions from the surface hoar samples appear unimodal, and were overall smaller than the fresh snow sample, with a peak around 0.3 µm. The fresh snow sample contained very large rBC particles that had a pronounced bimodality in peak size distributions, with peaks around 0.2 µm and 2 µm. rBC concentrations ranged from a minimum of 3 µg-rBC/L-H2O in light-colored patches at the beginning and end of the melt season, to a maximum of 32 µg-rBC/L-H2O in a dark patch in early August. On average, rBC concentrations were higher (20 µg-rBC/L-H2O ± 10 µg-rBC/L-H2O) in patches that were visibly dark compared to medium patches (7 µg-rBC/L-H2O ± 2 µg-rBC/L-H2O) and light patches (4 µg-rBC/L-H2O ± 1 µg-rBC/L-H2O), suggesting BC aggregation contributed to snow aging on the GrIS, and vice versa. Additionally, concentrations peaked in light and dark patches in early August, which is likely due to smoke transport from wildfires in Northern Canada and Alaska as supported by the Navy Aerosol Analysis and Prediction System (NAAPS) reanalysis model. According to model output, 26 mg/m3 of biomass burning derived smoke was deposited between April 1st and August 30th, of which 85 % came from wet deposition and 67 % was deposited during our sample collection timeframe. The increase in rBC concentration and size distributions immediately after modelled smoke deposition fluxes suggest biomass burning smoke is a source of BC to the dark zone of the GRIS. Thus, role of BC in the seasonal evolution of the ice-albedo feedback should continue to be investigated in the bare-ice zone of the GrIS.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".