Transport Working Group

All users interested in the GEOS-Chem transport scheme are encouraged to subscribe to the transport email list (click on the link in the contact information section section below).

Contact information

Transport Working Group Co-Chairs	Andrea Molod and Hongyu Liu
Transport Working Group email list	geos-chem-transport [at] g.harvard.edu
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--Bob Y. (talk) 18:38, 21 August 2015 (UTC)

Current GEOS-Chem Transport Projects (please add yours!)

User Group	Description	Contact Person
U. Toronto	Assessing impact of transport biases on methane simulation and applying weak constraint 4D-Var to correct them	Ilya Stanevich
U. Toronto	Characterizing model transport errors using weak constraint 4D-Var	Martin Keller
U. Toronto	Quantifying the impact of errors in PBL mixing on CO2	Wei Lu
Harvard	Examining the effect of grid resolution on vertical transport and convective mass fluxes	Karen Yu
Harvard	Quantifying the impact of numerical diffusion on plume transport and comparing to observed atmospheric diffusion	Sebastian D. Eastham
Harvard	Assessing the co-benefits of increasing vertical and horizontal grid resolutions for tracer transport	Jiawei Zhuang
Dalhousie	Implementation of a new PBL mixing scheme	Aaron van Donkelaar
NIA / NASA Langley	Constraints on Precipitation Scavenging and Transport of Soluble Trace Species From Airborne and Surface Radionuclide (222Rn, 210Pb, 7Be, 10Be) Observations	Bo Zhang Hongyu Liu
Add yours here!

Current GEOS-Chem Transport Issues

Text to be added

Common set of tracers in GEOS-Chem and GEOS

The transport Working Group has proposed implementing additional tracers in GEOS-Chem for benchmarking purposes and diagnosing transport in GEOS-Chem compared to GEOS-5.

Honygyu Liu wrote:

Andrea and I would like to seek your comment on the effort needed to implement additional tracers in GCC and GCHP. See below for the list of tracers in GEOS that Andrea sent earlier.

It would be straightforward to implement all these tracers in GCHP. Per Andrea, all we need to do is to download some additional code (called the tracer gridded component "Tracer_GridComp" in GEOS).

If we want the same tracer suites in GCC (e.g., an extension of current radionuclide tracers, simulation type "1") as in GCHP, how much effort would it be? Is there any practical reason that a reduced number of tracers is preferred in GCC?

Bob Yantosca replied:

It looks as if most of these are passive species with a fixed atmospheric lifetime, right? If so, then it is very straightforward to add these to any GEOS-Chem simulation. See:

  http://wiki.seas.harvard.edu/geos-chem/index.php/HEMCO_examples#Passive_species            

So basically in the passive species menu of input.geos you would list the names of each passive species, its default concentrations, and atmospheric lifetime is. If the species has an emissions flux, you can specify that with a corresponding entry in the HEMCO_Config.rc file, as described on the wiki.

I think the only modification we might need to make is that you are currently limited to 20 passive species but that is easy to extend by just changing a parameter value.

--Melissa Sulprizio (talk) 18:42, 23 February 2018 (UTC)

List of tracers in GEOS

17 GMI tracers: https://gmi.gsfc.nasa.gov/uploads/files/gmi_tracersuite.pdf

Additional Tracers in GEOS - used in part to get an age spectrum

# Name     Units        Long Name
# -----    ------       --------------------------------
nh_5      'mol mol-1'   Northern Hemisphere 5 day tracer
nh_50     'mol mol-1'   Northern Hemisphere 50 day tracer
sh_5      'mol mol-1'   Southern Hemisphere 5 day tracer
sh_50     'mol mol-1'   Southern Hemisphere 50 day tracer
ntr_5     'mol mol-1'   Northern Hemisphere Subtropical 5 day tracer
ntr_50    'mol mol-1'   Northern Hemisphere Subtropical 50 day tracer
str_5     'mol mol-1'   Southern Hemisphere Subtropical 5 day tracer
str_50    'mol mol-1'   Southern Hemisphere Subtropical 50 day tracer
tr_5      'mol mol-1'   Tropical 5 day tracer
tr_50     'mol mol-1'   Tropical 50 day tracer
e90       'mol mol-1'   Constant emission 90 day tracer
e90_n     'mol mol-1'   Constant emission Northern Hemisphere 90 day tracer
e90_s     'mol mol-1'   Constant emission Southern Hemisphere 90 day tracer
st80_25   'mol mol-1'   Stratospheric source 25 day tracer
aoa_nh    'days'        Age of air tracer (Northern Hemisphere surface source)
::

and a few others

CH3I      'mol mol-1'   Methyl iodide
st80_25   'mol mol-1'   Stratosphere source 25 day tracer
CO_50_na  'mol mol-1'   Anthro CO North America 50 day tracer

--Melissa Sulprizio (talk) 18:42, 23 February 2018 (UTC)

Tracer suggestions

Chris Holmes wrote:

Another tracer suggestion: I like and use the "origin" tracers defined by Clara Orbe et al. (2013). These tracers give the fraction of air that that originates in specified source regions.

In addition to diagnosing transport, I think the tracers will be useful as templates for users to modify for their own purposes (e.g. customizing source regions). For that reason, a comprehensive set of tracers would be useful, if they can be optional.

Reference

Orbe, C., M. Holzer, L. M. Polvani, and D. Waugh (2013), Air-mass origin as a diagnostic of tropospheric transport, J. Geophys. Res. Atmos., 118, 1459–1470, doi:10.1002/jgrd.50133.

--Melissa Sulprizio (talk) 18:42, 23 February 2018 (UTC)