Grid-independent emissions

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Overview

Dust emissions

This update will be included in GEOS-Chem 12.4.0.

Developer: David Ridley (CARB, formerly MIT)

Dave Ridley wrote:

The method that I’ve settled on is relatively simple and doesn’t require too many code alterations. Here is a link to the standalone code, a README (in /standalone/), the code files with the key changes and a diff patch from v11-01:

https://www.dropbox.com/sh/nmx7qhm5tlpt0aa/AAAF_-M1DBOVO1hwetpefd1wa?dl=0

There are a few points that need ironing out:

Because of how HEMCO_sa_Grid.rc wants a grid x and y to be listed on a single line, this becomes an issue within the HEMCO code for the maximum allowable line length. I went through and changed all occurrences of these to prevent crashing when listing the 0.5 x 625 grid points, but now it means that every line in the HEMCO log file is very long, making the file big and a mess to read. So there is definitely a better solution I’m sure (either how the grid is read into HEMCO or trimming the blankspace on lines written to the log file), but that is the source of all the changes in the HEMCO/Core files that you’ll see in the diff patch.

Alterations made to Makefile_header and CMN_SIZE_mod so that compilation will run far enough with GRID=0.5x0.625 MET=merra2 so that hemco_standalone.x is generated and dust emissions can be calculated at this resolution. Ideally need to extend this to GEOS-FP 0.25 x 0.3125 capability. I’ve not done this yet.

Currently the scaling factor is 1.0 for the dust when pre-processor switches MERRA-2 and 0.5x0.625 are on, i.e. when HEMCO standalone is calculating offline emissions. Then the scaling factor is applied to the offline emissions when read in, by the 606 scale factor in HEMCO_Config.rc. This means that the scale factors should be unchanged when running dust online. There may be a better way of doing this that is consistent for online and offline dust emissions.

A random wetscav (potential) bug fixed with old NSOL reference changes. I’m not sure if it actually makes a difference, just for consistency if I’m correct.

I think those are the main points.

Once the model has run again I can send over some details of the analysis, or at least add them to a wiki. The initial testing shows a <1% change in emissions when running offline at 2x2.5 vs online at 2x2.5, which is good! Using the 0.5x0.625 emissions increases the global dust emission by ~40-50%. The analysis will indicate when and where this happens, improvement relative to observations and the scaling factor that should be set in HEMCO_Config (currently defaulting to 0.0004).

--Melissa Sulprizio (talk) 12:58, 7 December 2018 (UTC)

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This update will be included in GEOS-Chem 12.4.0.

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This update will be included in GEOS-Chem 12.4.0.

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This update will be included in GEOS-Chem 12.4.0.

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This update will be included in GEOS-Chem 12.4.0.

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