**********************************************************************
*** Atmospheric CO concentrations (ppbv)  derived from flask       ***
*** samples collected at Macquarie Island, Australia               ***
*** Source: L.P. Steele                                            ***
***              P.B. Krummel                                      ***  
***              R.L. Langenfelds                                  ***
***              Commonwealth Scientific,                          ***
***              and Industrial Research Organisation,             ***
***              Aspendale, Victoria,                              *** 
***              Australia  3195                                   ***                   
***                                                                ***   
*** February 2003                                                  ***
***                                                                ***
**********************************************************************

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

1992		47.76	45.84	46.15	50.79	55.62	59.08	61.66	62.34	61.68	57.62	48.9	
1993	42.68	41.31	39.76	40.56	46.31	50.79	53.38	59.95	65.22	63.78	57.98	49.71	50.95
1994	43.76	43.17	45.14	46.9	49.56	53.89	57.44	61.7	66.14	66.57	63.23	56.7	54.52
1995	48.11	43.73	43.41	45.16	49.01	51.84	55.63	59.53	63.86	69.58	67.21	55.99	54.42
1996	46.45	43.83	42.34	41.96	45.15	49.86	53.54	57.79	62.11	62.67	58.54	49.67	51.16
1997	41.76	39.73	40.92	44.51	49.17	53.18	56.99	60.25	63.24	67.37	65.39	55.84	53.20
1998	48.45	44.42	42.4	44.46	50.59	56.08	60.15	65.18	69.22	69.11	62.86	53.59	55.54
1999	44.59	40.05	39.58	40.5	45.18	53.04	56.14	58.49	66.67	70.43	64.56	53.55	52.73
2000	43.33	39.21	39.7	42.68	46.28	51.3	56.83	59.99	61.01	59.19	53.84	46.99	50.03
2001	40.84	38.23	39.18	41.81	45.03	49.85	56.06	58.68	62.11	64.18	57.55	49.57	50.26


Monthly values, expressed in parts per billion by volume (ppbv), are linked to the gravimetrically derived 
scale of NOAA/CMDL using a single high-pressure cylinder standard with a CO mole fraction of 196 ppbv.  
Stability of the CSIRO scale and variations in instrument response are monitored with about 20 high 
pressure cylinder standards, with lifetimes of 4 to 10 or more years, spanning a CO range of 20 to 
400 ppbv.  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.  Annual values are the arithmetic 
means of the 12 monthly values.