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*** Atmospheric CH4 concentrations (ppbv) derived from flask       ***
*** samples collected at Mauna Loa, Hawaii, USA                    ***
*** Source: L.P. Steele                                            ***
***              P.B. Krummel                                      ***  
***              R.L. Langenfelds                                  ***
***              Commonwealth Scientific,                          ***
***              and Industrial Research Organisation,             ***
***              Aspendale, Victoria,                              *** 
***              Australia  3195                                   ***                   
***                                                                ***   
*** January 2003                                                   ***
***                                                                ***
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Year	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Ann Ave

1991						1752.65	1741.59	1704.23	1716.91	1735.83	1739.23	1740.21	
1992	1734.47	1733.01	1742.77	1736.22	1718.74	1722.93	1717.97	1700.58	1704.94	1704.83	1707.44	1738.56	1721.87
1993	1748.59	1739.59	1735.88	1725.9	1714.29	1707.13	1703.41	1709.92	1724.37	1731.23	1738.13	1745.23	1726.97
1994	1729.49	1713.55	1719.76	1728.8	1724.92	1716.03	1708.65	1710.68	1742	1764.67	1754.76	1749.9	1730.27
1995	1740.5	1746	1762.45	1748.1	1731.83	1734.86	1732.2	1732.28	1737.25	1728.15	1730.08	1744.46	1739.01
1996	1743.89	1742.44	1745.62	1738.29	1731.77	1732.08	1730.43	1728.53	1736.69	1746.63	1751.86	1761.65	1740.82
1997	1751.58	1735.7	1749.52	1759.75	1754.49	1751.21	1729.29	1718.53	1743.41	1757.31	1763.06	1766.37	1748.35
1998	1751.45	1751.16	1767.15	1766.28	1753.29	1754.32	1745.48	1733.95	1754.82	1766.6	1768.42	1776.52	1757.45
1999	1772.68	1767.38	1773.17	1768.44	1746.31	1742.87	1742.34	1741.65	1757.81	1772.18	1777.94	1775.76	1761.54
2000	1772.83	1777.33	1783.55	1770.98	1753.76	1751.89	1745.13	1739.62	1754.05	1772.88	1775.07	1767.62	1763.73
2001	1767.29	1775.09	1788.8	1793.03	1769.75	1750.16	1745.42	1743.07	1751.36	1761.81	1773.36	1777.36	1766.38

Monthly values are expressed in parts per billion by volume (ppbv) and reported in the CSIRO94 CH4 Scale 
[Steele, et al., 1996, pp. 107-110, in: Baseline Atmospheric Program (Australia) 1994-95, edited 
by R.J.Francey, A.L. Dick, and N. Derek]. Monthly values are calculated as the mean of the daily values 
from a smooth curve fit to the data using curve-fitting routines described by Thoning et al., 1989 
(J. Geophys. Res. 94, 8549-8565). Annual values are the arithmetic means of the 12 monthly values.