Impact of the Mount Pinatubo eruption on cirrus clouds formed by homogeneous freezing in the ECHAM4 GCM
Bibliographic record
Abstract
Volcanic emissions may have the potential to alter cirrus cloud properties. Here we conduct different sensitivity studies with the ECHAM4 general circulation model for 2.5 years after the Mount Pinatubo eruption (July 1991 to December 1993) and compare homogeneous cirrus formation caused by sedimenting sulfate particles produced in the eruption plume with homogeneous cirrus formation in the undisturbed atmosphere. In the first scenario, the sulfate aerosol mass from Pinatubo is added to the background aerosol concentration assuming a monomodal aerosol. Here the aerosol concentration increases by up to 3000 cm −3 in 1992, which can be regarded as an upper limit more representative for the first months after the eruption. The ice crystal number concentration increases by up to 1 cm −3 near the tropical tropopause more than doubling the pre‐existing concentration in this region one year after the eruption. In the second, more realistic, scenario the Pinatubo aerosol is added to a bimodal background size distribution as a separate large particle mode. Here the aerosol number concentration increases by 10–25 cm −3 , which can be regarded as a lower bound more representative for what has been observed in 1992. Then the ice crystal number increases at most 50% in the tropics in 1992. Satellite observations show an increase in ice water path starting in 1992 that could be related to either the Mount Pinatubo eruption or the El Niño event or both but a decrease in total cloud cover. While there is no trend on cloud microphysical or optical properties in our second scenario, the first scenario shows a pronounced increase in ice water path and a noticeable impact on cloud radiative forcing.
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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 | 0.002 | 0.001 |
| 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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 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".