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- Reduced volcanic outgassing of SO2 from certain volcanoes based on recent observations.
- Implemented cap on anthropogenic primary organic matter (OM) emissions to reduce excesses in highly polluted regions.
- Increased numerical precision in prescribed emission fields to remove artefacts.
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- Numerical improvements to the aerosol and chemistry schemes to accommodate running the forecasts in single precision as noted above.
Impact of the new cycle
The changes of this upgrade were evaluated with independent observations for Q1 and Q3 of 2020:
- strong improvements for PM2.5 over China and India in both bias and RMSE because of reduced PM2.5 (the overall bias is now slightly negative)
- nearly neutral impact for PM2.5 and PM10 elsewhere. Where biases were increased, the RMSE was often improved
- small reduction in tropospheric and surface ozone, which is an improvement
- neutral results for CO
Technical details of the new cycle
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