Stratospheric impact of the Chisholm pyrocumulonimbus eruption: 1. Earth‐viewing satellite perspective
Bibliographic record
Abstract
The pyrocumulonimbus storm near Chisholm, Alberta, on 28 May 2001 has been studied in depth. However, the impact of this eruption on the lower stratosphere has not been characterized. Here and in a companion paper we explore this topic. This paper focuses on the “young” Chisholm smoke plume, from the age of ∼3 h to 1 week, as observed by Earth‐viewing satellite instruments. (The companion paper presents strictly profile data.) GOES visible and infrared image loops reveal the pyroconvective life cycle and initial transport of the smoke cloud. MISR stereographic heights are the first of their kind for a stratospheric cloud, showing smoke up to 5 km above the tropopause on 29 May. MODIS IR and visible images are analyzed to give constraints on plume height, thickness, and particle size. Infrared brightness temperature analyses reveal unique aspects of the “day‐after” Chisholm plume. Particle sizes are 1/3 to 1/2 compared to normal cirrus crystals. The daytime 29 May plume is optically thick at tropopause temperatures yet smoky brown. A transition from deep anvil blow off to “dry” smoke is still occurring after ∼1.5 d. TOMS aerosol index is used as a proxy for areas of particularly high smoke plume altitude. The Chisholm smoke in the upper troposphere and lower stratosphere is traced with AI for 1 week as the plume blows across North America to western Europe. First estimates are made of stratospheric smoke mass in relation to emissions during pyroconvection. The 29 May stratospheric Chisholm pyroCb plume contains a mass between ∼1.39 × 10 4 and 1.09 × 10 5 t. This represents between ∼10% and 121% of total particle mass emitted from the fire on 28 May, calling into question some frequently assumed values for smoke single scatter albedo and/or emission estimates. Strictly in terms of mass, the stratospheric Chisholm plume amounted to ∼15% of background Northern Hemispheric stratospheric sulfate aerosol. Overall, the young pyroCb plume is seen to be a peculiar mixture of smoke aerosols and water‐ice that confounds operational cloud/aerosol detection routines and exhibits extreme, and still mysterious, composition and life cycle features.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".