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***  Concentrations of CH4 from the Law Dome (East Side,                   ***
***  "DE08" Site) Ice Core(a)                                              ***
***                                                                        ***
***  September 1994                                                        ***
***                                                                        ***
***  Source: D.M. Etheridge                                                ***
***          G.I. Pearman                                                  ***
***          P.J. Fraser                                                   ***
***          Commonwealth Scientific and Industrial Research Organisation  ***
***          Aspendale, Victoria, Australia                                ***
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Year      CH4           CH4
of air    concentration concentration
enclosure sample value  smoothing-spline
(A.D.)    (ppbv)        value
                        (ppbv)(b)
1841   806   823
1841   823  -999
1841   825  -999
1841   829  -999
1841   837  -999
1842   814   823
1842   825  -999
1843   825   824
1846   835   826
1854   819   831
1861   848   836
1862   823   837
1862   841  -999
1862   830  -999
1867   833   843
1867   848  -999
1872   876   848
1875   842   851
1881   874   858
1882   866   859
1883   857   860
1885   854   863
1891   866   872
1898   889   887
1903   922   902
1903   873  -999
1903   892  -999
1913   919   942
1916   960   956
1918   967   967
1921  1026   983
1923   982   994
1923   955  -999
1923   984  -999
1923   968  -999
1927  1047  1016
1927  1017  -999
1927  1033  -999
1927  1023  -999
1929  1015  1027
1929  1019  -999
1929  1056  -999
1933  1036  1049
1935  1111  1060
1940  1094  1085
1940  1120  -999
1940  1090  -999
1941  1067  1091
1943  1095  1101
1943  1127  -999
1944  1114  1106
1944  1116  -999
1947  1107  1124
1949  1168  1136
1950  1114  1143
1951  1120  1150
1952  1161  1158
1953  1159  1166
1955  1155  1183
1955  1160  -999
1958  1171  1212
1959  1220  1223
1959  1205  -999
1960  1238  1234
1960  1221  -999
1960  1225  -999
1964  1277  1283
1964  1284  -999
1967  1306  1324
1968  1354  1337
1968  1337  -999
1970  1370  1366
1971  1364  1380
1972  1430  1394
1972  1411  -999
1972  1403  -999
1972  1446  -999
1973  1408  1409
1973  1418  -999
1974  1427  1423
1974  1392  -999
1974  1395  -999
1974  1408  -999
1974  1449  -999
1975  1438  1438
1978  1504  1481

(a) These atmospheric CH4 concentrations derived from the Law Dome DE08 ice core 
were published in Ethridge et al. (1992).
(b) Smoothing-spline values were calculated by fitting a spline curve with a period 
of 50% attenuation of 50 years. These parameters were chosen to generate a spline curve 
that dampens variations in the data with periods less than about twice the air-age
resolution (80% distribution width) of 14 years. For further details, see Etheride et al. 
(1992) and Enting (1987).