**********************************************************************
*** Atmospheric H2 concentrations (ppbv) derived from flask       ***
*** samples collected at Shetland Islands, Scotland                ***
*** 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												494.55	
1993	503.9	504.91	511.06	513.14	511.75	508.94	496.55	490.98	495.13	492.18	483.11	486.26	499.83
1994	498.75	504.58	509.09	514.47	514.64	505.59	484.91	464.59	468.42	482.27	485.55	492.15	493.75
1995	503.26	505.88	508.85	511.3	506.8	509.03	508.2	493.86	487.54	487.29	486.21	492.53	500.06
1996	500.84	506.98	516.59	522.48	519.18	514.87	509.05	496.54	489.1	488.88	490.52	498.91	504.50
1997	505.64	506.37	510.63	514.17	514.09	509.61	501.87	492.1	480.99	481.1	489.62	493.7	499.99
1998	497.25	507.76	517.39	519.46	519.61	520.57	514.86	503.84	499.28	500.21	502.02	507.03	509.11
1999	515.35	521.26	525.61	528.3	526.89	522.32	513.11	506.25	504.44	500	496.91	498.03	513.21
2000	505.24	514	519.63	523.26	522.41	520.44	510.29	493.06	482.76	480.72	489.99	500.36	505.18
2001	502.53	503.56	508.96	513.24	516.03	526.28	520.51	489.8	474.42	477.55	478.79	483.58	499.60

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.