Sources of carbonaceous aerosols over the United States and implications for natural visibility
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A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
No Canadian affiliation. An affiliation-only frame — the usual design — would never have seen this work. It is one of the works that make the case for inverting the frame.
Machine scores (provisional)
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
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.
- Teacher spread
- 0.281 · how far apart the two teachers sit on this one work
- Validation status
score_only:v0-immature-baseline· verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it
Abstract
We use a global three‐dimensional model (GEOS‐CHEM) to better quantify the sources of elemental carbon (EC) and organic carbon (OC) aerosols in the United States through simulation of year‐round observations for 1998 at a network of 45 sites (Interagency Monitoring of Protected Visual Environments (IMPROVE)). Simulation with our best a priori understanding of sources, including global satellite data to constrain fire emissions, captures most of the variance in the observations (R 2 = 0.84 for EC, 0.67 for OC) with a low bias of 15% for EC and 26% for OC. Multiple linear regression to fit the IMPROVE data yields best estimates of 1998 U.S. sources of 0.60 Tg year −1 EC and 0.52 Tg year −1 OC from fossil fuel; 0.07 Tg year −1 EC and 0.89 Tg year −1 OC from biofuel; 0.08 Tg year −1 EC and 0.60 Tg year −1 OC from wildfires; and 1.10 Tg year −1 OC from vegetation. We find that fires in Mexico and Canada contributed 40–70% of annual mean natural EC in the United States for 1998 and 20–30% of annual mean natural OC. Transpacific transport from Asian pollution sources amounted to less than 10% of the natural EC and less than 2% of the natural OC; in contrast to ozone, we find that intercontinental transport of anthropogenic carbonaceous aerosols does not enhance significantly the natural background. IMPROVE observations and model simulations for the summer of 1995 show that Canadian fire emissions can produce large events of elevated EC and OC in the southeastern United States. Our best estimates of mean natural concentrations of EC and OC in the United States, using a model simulation with climatological monthly mean fire emissions, are 2–3 times higher than the default values recommended by the U.S. Environmental Protection Agency for visibility calculations, except for OC in the eastern United States (16% lower).
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The record
- Venue
- Journal of Geophysical Research Atmospheres
- Topic
- Atmospheric chemistry and aerosols
- Field
- Earth and Planetary Sciences
- Canadian institutions
- —
- Funders
- —
- Keywords
- Environmental scienceAtmospheric sciencesSatelliteAir pollutionPollutionAerosolMeteorologyClimatologyGeographyChemistryGeology
- Has abstract in OpenAlex
- yes