GEOS-Chem Newsletter October 2010

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Dear GEOS-Chem Users,

Here is your October GEOS-Chem Newsletter, just in time for Halloween!

Thank you for your continued support of GEOS-Chem.

Bob Yantosca and Claire Carouge

What's new in the GEOS-Chem community

The 5th GEOS-Chem Scientific and Users' Meeting

Harvard University will host the 5th GEOS-Chem Scientific and Users' Meeting from May 2-5, 2011. Please mark your calendars!

We invite you to view the GEOS-Chem meeting web page, We shall add information about local hotels shortly.

Claire's departure for Australia

Claire Carouge wrote:

Hi everyone,
As Daniel announced previously I am leaving for Australia. But I will keep working for GEOS-Chem Support for a while.
I am leaving the US on Tuesday 26th of October. I will go first for a week of vacations in France and then I'll go to live in the land down under. Although I might be able to connect sometimes from France, Bob will be mainly alone to insure the support from the October 27th to November 3rd, which as always means some delays to reply to emails.
My move to Australia presents some advantage like a near 24h support for GEOS-Chem. This is good news for people working in Asia (and the graduate students of all countries). At the same time, this means that Bob and I won't be able to communicate directly with each other as we do now. So this could mean some delays in responding to your questions and inquiries.
In addition, Bob and I will definitely need a period of transition to get fully organized. Although we will try to keep this transition period short, we ask for your patience during this time.
Also, to help us do a better work, we would like to remind you of a few things:
1) Please send all questions/inquiries to It helps us a lot to be aware of all problems and solutions with GEOS-Chem. Even if you know one of us is better suited to reply to you, please forget about our personal emails.
2) Don't forget that the wiki is a good source of information. When looking for something specific, it is often faster to use the search capability (in the menu on the left of the pages). Also, there is a RSS feed for the wiki, we encourage you to subscribe to it, so you can follow the modifications made.
3) One more thing about the wiki: anyone can contribute. Any GEOS-Chem user can open an account and then edit the wiki. The wiki is not a tool of communication from the support team to the users community, but from anyone of the GEOS-Chem community to anyone. So please, if you know of some missing information that could be useful to the community, don't wait to be asked for it and edit the wiki!
4) Please recall that the following types of GEOS-Chem simulations:
are maintained by the user community. Bob and I typically do not run these simulations, except to do debugging and testing before adding submitted updates from users into the standard code. Therefore, we are not always aware of the most recent updates/issues with these simulations until someone contacts us.
If you have questions about these simulations (other than coding or machine issues), or are looking for restart files or other data, we invite you to submit your questions to the relevant Working Group email list or to the main GEOS-Chem email list (geos-chem at For GCAP simulations, please contact Loretta Mickley.
5) Bob and I will try to arrange our schedules so that we can respond to your requests in a timely manner. However, please keep in mind that we both must balance the user support tasks with other priorities (e.g. continuing model development, column code development, web and wiki upkeep, and various other side-projects). So depending on circumstances one of us might not be immediately available to respond to your request right away.
I hope that working from the other side of the world will prove to be successful and that no one will have to complain about poor support.

Daniel Jacob wins 2010 Haagen-Smit prize

Please join us in congratulating Daniel Jacob, who is the recipient of the Haagen-Smit prize for 2010! Daniel was nominated for his paper Heterogeneous Chemistry and Tropospheric Ozone (Atmos. Environ., 34, 2131-2159, 2000).

The Haagen-Smit Prize is given annually to two papers previously published in Atmospheric Environment and covering different science areas. Additional information about this award and the selection committee members can be found at HERE.

Read more here ...

GEOS-Chem Steering Committee

The next GEOS-Chem Steering Committee date is Tuesday, January 25th, 2011 @ 10:30 ET (15:30 GMT).

Please contact your Working Group chairpersons if have any items that you would address to the Steering Committee.

We invite you to read the minutes from the September 21st Steering Committee Meeting.

GEOS-Chem Working Groups

We invite all GEOS-Chem users (especially new users) to join a Working Group and sign up for the relevant email list. Working Groups are designed to foster discussion between GEOS-Chem users who are doing research in similar areas.

Each GEOS-Chem user should also post a short description of their project(s) on the relevant Working Group wiki page. Please remove any obsolete projects, add new ones, and review the work planned by other groups. This will allow the Working Group Chairpersons to be informed about the type of research that is being conducted by individual GEOS-Chem users while avoiding duplication of effort.

GEOS-Chem model development update

GEOS-Chem v9-01-01

GEOS-Chem v9-01-01 will be the next version to be released. It will contain the following updates:

  1. Compatibility with MERRA met fields (GEOS-Chem Support Team)
  2. Modified algorithms for convective updraft scavenging and wet deposition (H. Amos, B. Corbitt, Q. Wang et al)
  3. Bug fix: Restore capability to start GEOS-Chem from any arbitrary date & time (GEOS-Chem Support Team)

At present we are validating the new wet scavenging and convective updraft scavenging algorithms for the new MERRA met data product in GEOS_Chem v9-01-01. The work is ongoing.

MERRA reanalysis met fields


The GEOS-Chem Support Team has started the process of modifying GEOS-Chem for use with the MERRA met field product. MERRA is a 30-year reanalysis done with GMAO's GEOS-5.2.0 GCM. For the latest information about MERRA, please the following wiki pages:

  1. MERRA
  2. List of MERRA met fields used by GEOS-Chem
  3. MERRA implementation details

Data availability

The GEOS-Chem Support Team has started to download and regrid the MERRA data for GEOS-Chem. At present we have downloaded the following time periods.

  • 2008: full year 4° x 5°
  • 1997-2005: full year 4° x 5°

We plan to obtain the full 30-year MERRA archive (1979-2010). At present, we are only regridding the data to 4° x 5° due to disk storage limitations at Harvard. After a planned storage upgrade we will have the capacity to also store the 2° x 2.5° MERRA data as well.

We are concentrating on obtaining the time period 1995-2005. Once we have downloaded the MERRA data for this time period, we will recompute the OTD/LIS lightning flash redistribution factors (which are a crucial part of the lightning NOx emissions scheme).

In the pipeline

The following updates will be added into GEOS-Chem following the v9-01-01 release.

Item Author(s) Status
APM aerosol microphysics Fangqun Yu APM is being validated with a nested grid simulation for Europe. Currently slated for inclusion after the release of GEOS-Chem v9-01-01.
Bromine chemistry mechanism Justin Parella We have begun the process to bring this into the standard code. Will be included after the release of GEOS-Chem v9-01-01.
Add scavenging by snow Qiaoqiao Wang Slated for inclusion into GEOS-Chem v9-01-01 or later versions.

For a complete list of outstanding code updates, please see our GEOS-Chem model development priorities page.

Column code update

An ESMF Gridded Component has been created which calls the GEOS-Chem column chemistry routines. Some key bugs have now been fixed and work to finalize the interface has begun. Bob is currently testing to make sure that the column chemistry code running within the ESMF environment returns the same output as when driven in a GEOS-Chem test environment. The work is ongoing.

At present, column code development is on the back burner due to the pressing need to modify GEOS-Chem to be driven by the MERRA reanalysis product from GMAO.

GEOS-Chem reference


The GEOS-Chem People and Projects and GEOS-Chem Publications pages have recently been updated.

Please send all new journal articale submissions to the GEOS-Chem support team at

We invite you to consult our Guidelines for Offering Co-authorship and GEOS-Chem Code Development History web pages if you are unsure how to give credit to GEOS-Chem developers.


We encourage all GEOS-Chem code developers and users to check the wiki frequently, as this is the place where the latest information about GEOS-Chem will be posted. The wiki is designed to be a two-way street of communication. Users should feel free to add content to the wiki pages that are most closely related to their research.

In particular, the GEOS-Chem Support Team has started a new effort to make sure that all 3rd-party code and data that is submitted into GEOS-Chem has a corresponding wiki page. This will ensure that all information can be shared transparently.

Please see the Recent Changes wiki page to see which wiki pages have been updated.

Finally, if you have not already done so, consider signing up for automatic wiki notification. You will be updated whenever someone modifies the GEOS-Chem'll never miss a discussion!

Email lists

All GEOS-Chem users should sign up for the GEOS-Chem Users email list, as well as one or more of the following Working Group email lists:

  1. GEOS-Chem Adjoint
  2. GEOS-Chem Aerosols
  3. GEOS-Chem Carbon Gases & Organics
  4. GEOS-Chem Hg & POPs
  5. GEOS-Chem Oxidants & Chemistry
  6. GEOS-Chem Regional Air Quality
  7. GEOS-Chem Sources & Sinks

Search engines

We have set up several GEOS-Chem search engines which will let you search for information in the GEOS-Chem website, wiki, and manual pages.

You can also search the GEOS-Chem wiki by means of the search box in the left column. It is often more efficient to search for a topic rather than to follow links down from the main page.

--Bob Y. 16:49, 28 October 2010 (EDT)