CH4 simulation

NOTE: Page under construction

This page contains information about the methane (CH4) simulation in GEOS-Chem.

Overview

The CH4 simulation in GEOS-Chem ...

Authors and collaborators

• Christopher Pickett-Heaps (Harvard)
• Kevin Wecht (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

Planned updates

Update methane emissions and add capability for North America nested grid

Note: This update is slated to be incorporated into GEOS-Chem v9-01-03 or later.

Kevin Wecht wrote:

I have some GEOS-Chem methane updates that I'd like to add to the standard code.

1. GFED emissions - I've updated GFED-2 and GFED-3 biomass burning to include methane emissions.
2. 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

--Melissa Payer 17:35, 2 February 2012 (EST)

Known issues

Error reading GWETTOP fields

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 )

For both annual and monthly mean GWETTOP. That seems to work and it reads the file for the proper simulation year.

--Melissa Payer 18:06, 2 February 2012 (EST)