Global Simulation of CH3Cl

Model Description

• GEOS-CHEM global 3D model (v.5.02)

• DAO GEOS-STRAT with simulation year from September 1996 - August 1997

• Resolution: 4 º latitude x 5 º longitude, 26 layers

CH3Cl Emissions used in this study

Sources Gg/year Data description

Biogenic 2,430Hypothetical tropical source (Lee-Taylor et al. [2001])

Biomass burning 910 GEIA Inventory (Lobert et al. [1999])

Ocean (net)

660 GEIA Inventory (Khalil et al. [1999])

160Calculated using saturation anomaly and transfer velocity (Khalil et al. [1999] and Wanninkhof [1992])

Salt marshes 170 Rhew et al. [1999]

Anthropogenic 162GEIA Inventory (McCulloch et al. [1999])

Wetlands 48 Varner et al. [1999]

Emission distributions for northern and southern hemisphere

N-H

0

20

40

60

80

100

120

140

1 2 3 4 5 6 7 8 9 10 11 12

Month

Em

issi

on

s (G

g)

S-H

0

20

40

60

80

100

120

140

1 2 3 4 5 6 7 8 9 10 11 12

Month

Em

issi

on

s (G

g)

ocbbanbgsmwtGEIA_ oc

Annual net oceanic flux

Calculated GEIA Inventory

I-a) Concentration comparison between observations and model at six surface stations (1/2)

I-a) Concentration comparison between observations and model at six surface stations (2/2)

II) Vertical profile comparison between observations and model

II) Vertical profile comparison: observations VS. model (1/7)

II) Vertical profile comparison: observations VS. model (2/7)

II) Vertical profile comparison: observations VS. model (3/7)

II) Vertical profile comparison: observations VS. model (4/7)

II) Vertical profile comparison: observations VS. model (5/7)

II) Vertical profile comparison: observations VS. model (6/7)

II) Vertical profile comparison: observations VS. model (7/7)

II) Vertical profile comparison between observations and model

III-a) Latitude-altitude concentration distributions: observations VS. model for TRACE-P region (east)

III-a) Latitude-altitude concentration distributions: observations VS. model for TRACE-P region (east)

III-a) Latitude-altitude concentration distributions: comparisons of biomass burning and biogenic CH3Cl to background concentrations

for TRACE-P region (east)

IV-a) Correlation CH3OH VS. CH3Cl for TRACE-P (east)

III-b) Latitude-altitude concentration distributions: observations VS. model for TRACE-P region (west)

III-b) Latitude-altitude concentration distributions: observations VS. model for TRACE-P region (west)

III-b) Latitude-altitude concentration distributions: comparisons of biomass burning and biogenic CH3Cl to background concentrations

for TRACE-P region (west)

Global Simulation of CH2O

GOME SEP 1996

GEOS-CHME SEP 1997

GEOS-CHEM (inactive OH) without Biogenic emissions

STD Inactive OH Inact. OH w/o 3-body rxn

NO

NO2

PRPE

Regional Simulations

RCTM GEOS-CHEM

• MM5 data assimilation at 70x70km, 20 layers (up to 14 km), and 5 min time step output

• Grell scheme with mid-level downdraft

• Lightning NOx parameterization by Allen et al. [2000] and Pickering et al. [1998]

• The same chemical module as GEOS-CHEM

• DAO data assimilation (GEOS-3) at 4°x5°, 48 layers (to 80 km), and 6-hour time step output

• Full O3-NOx-HC chemistry with 24 tracers and 120 species [Bey et al., 2001]

• Provides initial and boundary trace gas conditions for RCTM

500 mb