**********************************************************************
*** Atmospheric H2 concentrations (ppbv) derived from flask       ***
*** samples collected at Mauna Loa, Hawaii                         ***
*** Source: L.P. Steele                                            ***
***              P.B. Krummel                                      ***  
***              R.L. Langenfelds                                  ***
***              Commonwealth Scientific,                          ***
***              and Industrial Research Organisation,             ***
***              Aspendale, Victoria,                              *** 
***              Australia  3195                                   ***                   
***                                                                ***   
*** March 2003                                                     ***
***                                                                ***
**********************************************************************

Year	Jan.	Feb.	Mar.	Apr.	May	Jun.	Jul.	Aug.	Sep.	Oct.	Nov.	Dec.	Ann. Ave.

1992	512.35	509.84	520.18	532.84	536.8	534.72	525.95	518.3	516.4	514.72	510.72	504.62	519.79
1993	505.63	511.15	517.12	525.97	529.67	524.68	517.2	505.69	495.57	503.51	509.83	507.86	512.82
1994	512.7	516.27	515.93	521.43	523.72	519.51	521.09	521.08	518.34	517.02	514.37	515.75	518.10
1995	520.96	521.77	525.22	532.9	536.16	533.59	527.7	525.09	524.76	524.1	520.36	516.9	525.79
1996	517.68	518.59	523.35	531.02	533.68	532.31	526.21	522.57	522.1	517.91	514.08	515.44	522.91
1997	518.66	523.1	533.22	534.47	527.04	527.3	521.96	516.12	519.46	516.27	515.46	522.05	522.93
1998	525.39	528.8	539.87	544.51	537.97	538.78	539.61	534.95	533.48	532.88	526.49	526.76	534.12
1999	532.1	535.57	542.38	541	536.36	537.67	536.27	531.23	527.03	524.5	520.71	519.4	532.02
2000	522.69	525.77	531.51	539.85	542.35	535.5	526.39	517.61	514.34	515.34	513.52	519.43	525.36
2001	523.47	518.67	522.13	527.39	522.29	515.63	519.23	519.92	515.98	517.23	514.89	515.2	519.34

Monthly values are expressed in parts per billion per volume (ppbv) and reported in the CSIRO94 H2 scale. 
Monthly values were calculated as the mean of the daily values from a smooth curve fit to the data using 
the 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.