Viscosity and phase state of wildfire smoke particles in the stratosphere from pyrocumulonimbus events: an initial assessment
Bibliographic record
Abstract
Understanding the viscosity and phase state of biomass-burning organic aerosol (BBOA) from wildfires and pyrocumulonimbus (pyroCb) events in the stratosphere is critical for predicting their role in stratospheric multiphase chemistry and ozone depletion. However, the viscosity and phase state of BBOA under stratospheric conditions, including interactions with sulfuric acid (H₂SO₄), remain largely unquantified. In this study, we combine laboratory data with a thermodynamic model to predict the viscosity and phase state of BBOA under stratospheric conditions. Our results suggest that BBOA with a H₂SO₄-to-BBOA mass ratio of 0.37—an estimated upper limit for pyroCb smoke in the lower stratosphere after two months of aging— is highly viscous and frequently exists in a glassy state. Even at a higher H₂SO₄-to-BBOA mass ratio of 0.79 – an estimated upper limit after nine months of aging – BBOA can still transition to a glassy state under certain stratospheric conditions. In the glassy state, bulk reactions are suppressed, and multiphase chemistry may be limited to the particle surfaces. We also highlight key areas for future research needed to better constrain the viscosity and phase state of BBOA in the stratosphere and its subsequent impact on ozone.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 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".