**********************************************************************
*** Atmospheric CH4 concentrations (ppbv) derived from flask       ***
*** samples collected at Alert, NWT, Canada                        ***
*** 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					1777.33	1762.28	1759.77	1772.89	1786.6	1797.9	1806.28	1816.99	
1992	1828.44	1819.2	1810.88	1813.03	1802.36	1782.69	1772.41	1774.56	1782.41	1790.96	1804.29	1826.97	1800.68
1993	1834.25	1818.75	1813.7	1815.76	1796.76	1773.86	1769.92	1782.1	1795.07	1799.31	1799.69	1811.91	1800.92
1994	1824.04	1823.49	1825.82	1821.31	1803.9	1786.43	1775.26	1781.63	1797.98	1805.56	1808.86	1823.97	1806.52
1995	1840.69	1838.31	1824.88	1814.9	1801.41	1785.01	1782.41	1793.37	1805.36	1813.87	1817.13	1820.34	1811.47
1996	1835.61	1848.88	1838.39	1820.09	1809.37	1797.97	1785.77	1788.76	1803.28	1818.7	1828.21	1826.99	1816.84
1997	1829.86	1832.2	1825.15	1818.65	1808.34	1793.32	1786.88	1787.65	1800.45	1814.88	1813.19	1819.57	1810.85
1998	1844.97	1851.13	1830.29	1818.3	1816.22	1804.94	1797.52	1804.36	1816.97	1825.6	1831.5	1840.98	1823.57
1999	1848.44	1852.63	1848.35	1841.38	1829.3	1811.38	1805.82	1803.54	1808.76	1822.0	1826.79	1830.3	1827.39
2000	1841.12	1848.51	1845.89	1838.17	1826.38	1814.78	1806.73	1806.12	1817.91	1826.24	1829.15	1831.78	1827.73
2001	1833.97	1838.98	1841.69	1840.91	1830.64	1812.28	1802.31	1806.33	1815.49	1831.65	1845.07	1842.63	1828.5

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.