Difference between revisions of "Organics Working Group"

Latest revision as of 12:24, 10 August 2018

All users interested in the GEOS-Chem organic simulations (e.g. isoprene, etc) are encouraged to subscribe to the organics email list (click on the link in the contact information section below).

Contact information

--Bob Y. (talk) 18:25, 21 August 2015 (UTC)

Current Organics Projects (please add yours!)

--Dbm 16:12, 18 June 2013 (EDT)

Recently Completed Projects (please add yours!)

--Dbm 14:05, 12 May 2011 (EDT)

Development Priorities

--Dbm 16:11, 18 June 2013 (EDT)

Recent updates

The following development items relevant to organics have recently been added to GEOS-Chem:

--Dbm 16:12, 18 June 2013 (EDT)

GEIA anthropogenic scaling factors

This update was tested in the 1-month benchmark simulation v9-01-02h and approved on 12 Aug 2011.

A bug was discovered with the annual scale factors for anthropogenic emissions that get applied in anthroems.f (FLIQCO2), which take a ratio between the base year for the GEIA emissions (1985) and the simulation year. For southern Africa (Botswana region) 1985 scale value is abnormally low (<0.03), so that the (current year):1985 ratio ends up being very large (>500) and giving unrealistically high CO and hydrocarbon emissions.

In the scaling file (../GEOS_1x1/anth_scale_factors_200911/CO-AnnualScalar.geos.1x1), scale factors over Botswana increase by a factor of >100 between 1985 and 1990 (i.e. nearly tripling every year), and then more gradually and reasonably after that. As a fix I've created an updated version of the file CO-AnnualScalar.geos.1x1, which is here. The new file is the same as the old one except that the offending values over Botswana for 1985 have been replaced with their 1990 values. This brings things more in line with the surrounding countries.

Here is a visual summary of the scaling factors with the old file and the updated file.

It's possible there is a more accurate way to do this (e.g. scaling the 1990 values down by some amount to get back to 1985) but until someone looks at this specific region in detail (in which case one may not want to use GEIA anthropogenic emissions anyway) I think this is a good approach and should get rid of the problem.

Emily Fischer ran some comparisons before and after the fix. She writes:

I have posted some comparison plots for you to look through. I did a one-month test run using the file that you sent me last week. The "before" run has my updates to the ocean acetone source/sink included. For the hydrocarbons, I have before and after plots for surface mixing ratios. Note the very different scales in some cases. Your fix certainly is an improvement. I have included standard difference plots for CO, PAN and acetone.

--Dbm 15:30, 23 May 2011 (EDT)
--Bob Y. 11:19, 15 August 2011 (EDT)

Dicarbonyls

The discussion about known issues in the dicarbonyls simulation has now been moved to our separate Dicarbonyls simulation wiki page.

--Bob Y. 11:50, 28 April 2011 (EDT)

MEGAN

1. A description of MEGAN as implemented in GEOS-Chem up to v8-02-03 is posted HERE.
2. The discussion about the implementation of MEGAN 2.1 into GEOS-Chem v8-02-04 has been moved to a separate MEGAN biogenic emissions wiki page.
3. An update to the latest MEGAN 2.1 as described in Guenther et al. (2012) is now available and discussed here.

--Dbm 16:18, 18 June 2013 (EDT)

Criegee intermediates

This update was validated with 1-month benchmark simulation v11-01d and 1-year benchmark simulation v11-01d-Run1. This version was approved on 12 Dec 2015.

Explicit treatment of Criegee intermediates generated from alkene ozonolysis, and of their subsequent reactions with H2O, SO2, and other species, as described by Millet et al. (2015).

Eloïse Marais has streamlined Dylan Millet's mechanism to reduce species and speed up computation. This involved removing explicit treatment of some reactive intermediates. This streamlined version is currently undergoing validation.

--Melissa Sulprizio (talk) 18:15, 17 June 2015 (UTC)

Add missing Criegee intermediate reaction

This fix was included in GEOS-Chem 12.0.0.

Xin Chen (UMN) reported one Criegee intermediate reaction is missing in the GEOS-Chem chemical mechanisms.

CH2OO + CO = CH2O  :                         GCARR(1.20E-15, 0.0E+00, 0.0);       {2015/09/25; Millet2015; DBM,EAM}

This reaction has been missing since the original Criegee intermediates implementation in GEOS-Chem v11-01.

--Melissa Sulprizio (talk) 14:37, 17 July 2018 (UTC)