Surface Exchange of Methane (Fung et al. 1991)
This page offers access to a number of datasets which describe the exchange of methane between Earth's surface and atmosphere. They have been used in simulations of atmospheric CH4 using the GISS three-dimensional tracer transport model. An overview of the datasets and the model runs is given in Fung et al. (1991) (see References below).
Listed source strengths are global sums from the datasets. In many cases, they are arbitrary values assumed for mathematical convenience. See Fung et al. (1991) for a discussion of the actual source strengths and their uncertainties.
Individual files according to methane source may be downloaded via the following links; All are gzipped ASCII-text tables and none exceed 15-kb in length. All are at 1L×1° resolution.
Alternatively, you may download this entire collection of methane data in one of two ways:
- Complete tar-and-gzip archive (539 kiB) including all of the individual ASCII files.
- All data in one gzipped netCDF file (227 kiB).
Annual Datasets
Units are kg CH4 / m2 / year.
File Name | Description | Source Strength |
---|---|---|
CH4ANIMLS | Release from animals; see Lerner et al. (1988) | 75.8×109 kg/yr |
CH4MSW | Release from landfills (municipal solid waste) | 44.6×109 kg/yr |
CH4GASVENT | Release from venting of natural gas at wells | 10.3×109 kg/yr |
CH4GASLEAK | Release from pipeline leakage of natural gas | 9.5×109 kg/yr |
CH4COAL | Release from coal mining | 29.2×109 kg/yr |
CH4TRMITE | Release from termites | 20.0×109 kg/yr |
CH4HYDV | Release from hydrates/clathrates in Soviet Arctic | 10.0×109 kg/yr |
CH4HYDZ | Release from hydrates/clathrates at 76-84°N | 10.0×109 kg/yr |
CH4SOILABS | Loss via soil absorption | -25.1×109 kg/yr |
Monthly Datasets
Units are kg CH4 / m2 / month.
Name | Files | Description | Source Strength |
---|---|---|---|
CH4RICEC |
JAN,
FEB,
MAR,
APR,
MAY,
JUN, JUL, AUG, SEP, OCT, NOV, DEC |
Release from rice cultivation; see Matthews et al. (1991) | 79.7×109 kg/yr |
CH4WETL |
JAN,
FEB,
MAR,
APR,
MAY,
JUN, JUL, AUG, SEP, OCT, NOV, DEC |
Release from five wetland ecosystems; see Matthews and Fung (1987) | 108.8×109 kg/y |
CH4BOGS |
JAN,
FEB,
MAR,
APR,
MAY,
JUN, JUL, AUG, SEP, OCT, NOV, DEC |
Release from forested and non-forested bogs; see Matthews and Fung (1987) | 30.0×109 kg/yr |
CH4SWAMPS |
JAN,
FEB,
MAR,
APR,
MAY,
JUN, JUL, AUG, SEP, OCT, NOV, DEC |
Release from forested and non-forested swamps and alluvial formation; see Matthews and Fung (1987) | 39.1×109 kg/yr |
CH4TUNDRA | JAN,
FEB,
MAR,
APR,
MAY,
JUN, JUL, AUG, SEP, OCT, NOV, DEC |
Release from tundra; see Matthews and Fung (1987) | 3.2×109 kg/yr |
CH4BURN | JAN,
FEB,
MAR,
APR,
MAY,
JUN, JUL, AUG, SEP, OCT, NOV, DEC |
Release from biomass burning; see Fung et al. (1991) | 91.6×109 kg/yr |
Reading the Data
A snippet of FORTRAN code like the following can be used to read the ASCII text files.
PARAMETER (IM=360,JM=180) CHARACTER*80 INFO1, INFO2, INFO3 INTEGER IARRAY(IM,JM) C READ(10,910) INFO1 READ(10,910) INFO2 READ(10,910) INFO3 READ(10,920) IARRAY C C CAUTION: CHECK FOR MISSING AND UNDEFINED VALUES IN IARRAY FIRST, C BEFORE RESCALING AND OPERATING ON THE NUMBERS. THE VALUES OF C THESE PARAMETERS ARE GIVEN IN INFO1 AND INFO2. C 910 FORMAT (A80) 920 FORMAT (10(I8)) C STOP END
Explanation of Arrays
In the sample code, four variables are used to store the extracted information: INFO1, INFO2, INFO3, and IARRAY. The first three are character strings which describe the dataset. For example, in the file CH4RICEC.JAN, you will find:
RICE HARVEST:JAN DIMENSION = 360 X 180 SCALE = .1E+08 OCEAN = -999999 UNDEF = 9999999 MIN = 10 MAX = 55942 NUMREC = 6483 (NUMBER OF RECORDS IN DATA FILE)
i.e., they contain the following info:
- INFO1: A brief identifier of the dataset, the dimensions of array IARRAY, and a scaling factor. In the above example, the scaling factor ".1E+08" means that a value in the array should be divided by 0.1×108 (i.e., 107) to obtain the correct value in kg CH4 / m2 / month.
- INFO2: Value indicating an oceanic grid point, value indicating "undefined", and minimum and maximum real data values.
- INFO3: Number of data records in the dataset.
The surface grid IARRAY(I,J) is arranged so that:
- I = 1 is centered at 179.5°W
- I increases eastward
- J = 1 is centered at 89.5°S
- J increases northward
In other words:
87S - | - - - | - - - | - - - | - - | (1,3) | (2,3) | (3,3) | 88S - | - - - | - - - | - - - | - - | (1,2) | (2,2) | (3,2) | 89S - | - - - | - - - | - - - | - - | (1,1) | (2,1) | (3,1) | 90S - | - - - | - - - | - - - | - - 180W 179W 178W 177W
References
Papers and reports which describe the datasets include:
- Fung, I., J. John, J. Lerner, E. Matthews, M. Prather, L.P. Steele and P.J. Fraser 1991. Three-dimensional model synthesis of the global methane cycle. J. Geophys. Res. 96, 13033-13065.
- Gornitz, V., and I. Fung 1994. Potential distribution of methane hydrates in the world oceans. Global Biogeochem. Cycles 8, 335-347.
- Lerner, J., E. Matthews and I. Fung 1988. Methane emission from animals: A global high-resolution database. Global Biogeochem. Cycles 2, 139-156.
- Matthews, E., and I. Fung 1987. Methane emissions from natural wetlands: Global distribution, area and environmental characteristics of sources. Global Biogeochem. Cycles 1, 61-86.
- Matthews, E., I. Fung, and J. Lerner 1991. Methane emission from rice cultivation: Geographic and seasonal distribution of cultivated areas and emissions. Global Biogeochem. Cycles 5, 3-24.