CH4 simulation
This page contains information about the methane (CH4) simulation in GEOS-Chem.
Overview
The CH4 simulation in GEOS-Chem ...
Authors and collaborators
- Bram Maasakkers (Harvard)
- Alex Turner (Harvard)
- Kevin Wecht (Harvard)
- Christopher Pickett-Heaps (formerly @ Harvard)
- Jerome Drevet (formerly @ EPFL)
- James Wang (formerly @ Harvard)
CH4 simulation user groups
| User Group | Personnel | Projects |
|---|---|---|
| Harvard University | Christopher Pickett-Heaps Kevin Wecht |
Methane sources in the Arctic |
| U. Wollongong | Chris Chan Miller | Methane sources in tropical Australia |
Validation
Planned updates
Update methane emissions and add capability for North America nested grid
This update was tested in the 1-month benchmark simulation v9-01-03h and approved on 09 Mar 2012.
Kevin Wecht wrote:
- I have some GEOS-Chem methane updates that I'd like to add to the standard code.
- GFED emissions - I've updated GFED-2 and GFED-3 biomass burning to include methane emissions.
- Methane simulation - I've updated emissions and error catches to make the simulation compatible with the nested simulation over North America. I added linearized CH4 chemistry from GMI output (CH4 loss frequencies generated by Lee Murray). These changes should be made to the data directory:
- a. Replace Carbon_soil, Carbon_litter, and Wetfrac files in data directory (for all horizontal resolutions)
- b. Add 2010-2011 TSKIN and GWETTOP files to data directory (for all horizontal resolutions)
- c. Add nested north american OH files to OH directory
- d. Add biofuel emissions to data directory (for all horizontal resolutions)
- e. Add all emission files to data directory for nested North America simulation
The error in reading GWETTOP fields is also fixed in this update.
--Melissa Payer 17:35, 2 February 2012 (EST)
Update CH4 emissions to EDGAR v4.2
This update was tested in the 1-month benchmark simulation v9-02m and approved on 30 Jul 2013.
Kevin Wecht has prepared EDGAR v4.2 emissions of methane for 2004-2008. The data files are available at:
ftp://ftp.as.harvard.edu/pub/geos-chem/data/GEOS_0.5x0.666_NA/CH4_201305/ ftp://ftp.as.harvard.edu/pub/geos-chem/data/GEOS_2x2.5/CH4_201305/ ftp://ftp.as.harvard.edu/pub/geos-chem/data/GEOS_4x5/CH4_201305/
You can download these directories with anonymous FTP or the Wget utility. For instructions, please see Chapter 2.4, Downloading the GEOS-Chem shared data directories in the GEOS-Chem Online User's Guide.
Modifications to subroutines RICE_EMIS and ASEASONAL_ANTHRO_EMIS in global_ch4_mod.F include changing the directory names and updating CYEAR and XTAU as follows:
WRITE( CYEAR, '(i4)' ) GET_YEAR()
XTAU = GET_TAU0( 1, 1, GET_YEAR() )
IF ( GET_YEAR() .LT. 2004 ) THEN
CYEAR='2004'
XTAU = GET_TAU0( 1, 1, 2004 )
ENDIF
IF ( GET_YEAR() .GT. 2008 ) THEN
CYEAR='2008'
XTAU = GET_TAU0( 1, 1, 2008 )
ENDIF
--Melissa Payer 16:53, 2 July 2013 (EDT)
Fixes for wetland emissions
These issues were resolved during the public comment period following the provisional release of GEOS-Chem v9-02 and will be included in the official release of GEOS-Chem v9-02.
Kevin Wecht wrote:
- I have some updates/bug fixes to wetland emissions in the methane simulation. Both changes impact global_ch4_mod.F, subroutine WETLAND_EMIS.
- 1. Christopher Pickett-Heaps added a feature that zeroes wetland emissions if snow covers the ground. This was never incorporated into the standard code. It is included in the attached file.
- 2. Parameters in the subroutine are not correct. The following values are the correct and are included in the attached file:
MOIST_SCALE = 0.205
EMIT_FACT = 0.018
--Melissa Sulprizio 16:11, 23 January 2014 (EST)
References
Previous issues that are now resolved
Error reading GWETTOP fields
This update was tested in the 1-month benchmark simulation v9-01-03h and approved on 09 Mar 2012.
There is a file read error in the current CH4 simulation. We will fix this issue in GEOS-Chem v9-01-03.
In RICE_EMIS (global_ch4_mod.F), XTAU is reset to the wrong value when GEWTTOP is read. Kevin Wecht provided a fix that accounts for different availabilities of GEOS-4 and GEOS-5 met fields. Prior to setting FILENAME for GWETTOP , add the following:
YEAR = GET_YEAR()
#if defined( GEOS_5 )
IF ( YEAR .LT. 2004 ) YEAR = 2004
IF ( YEAR .GT. 2009 ) YEAR = 2009
#elif defined( GEOS_4 )
IF ( YEAR .LT. 2000 ) YEAR = 2000
IF ( YEAR .GT. 2006 ) YEAR = 2006
#endif
WRITE( CYEAR, '(i4)' ) YEAR
- Also change:
XTAU = GET_TAU0( 1, 1, GET_YEAR() )
and
XTAU = GET_TAU0( GET_MONTH(), 1, GET_YEAR() )
- to:
XTAU = GET_TAU0( 1, 1, YEAR )
and
XTAU = GET_TAU0( GET_MONTH(), 1, YEAR )
--Melissa Payer 18:06, 2 February 2012 (EST)
Outstanding Issues
None reported so far.
--Bob Y. 14:07, 30 March 2012 (EDT)