Western USA SO2 emissions too high

[ssmithClimate]

SO2 emissions in the western US are too high compared to US EPA state level emissions data. This is a consequence of our use of EDGAR emissions grids which use global proxy databases that evidently do not incorporate sub-regional information. This spatial allocation error is much larger than the uncertainty in emissions over the western US. (Over the Eastern US, the difference, is likely of comparable magnitude to emissions uncertainty.)

[ssmithClimate]

This issue will be addressed by on-going work to add the capability of producing sub-regional emission time series, such as at the US state level, and using these time series to produce gridded emissions.

[ssmithClimate]

We have created an approximate multiplicative correction grid for total SO2 emissions that shifts emissions from the western to eastern US. This is for testing and evaluation only at this point, but we are happy to share this to any groups who would find this useful.

[ssmithClimate]

The addition of new point data in recent gridded data, for example the CEDS SatEM version of the 2021_04_21 release have, at leas partially, corrected this issue.