**********************************************************************
*** Atmospheric CO concentrations (ppbv)  derived from flask       ***
*** samples collected at Mawson, Antarctica                        ***
*** 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.

1984					49.24	55.51	64.11	69.01	64.42	58.85	54.47	47.42	
1985	39.91	35.12	36.51	39.88	47.72	58.93	57.34	58.22	70.24	71.38	57.94	47.52	51.73
1986	46.17	42.14	40.8	48.37	54.44	57.26	63.85	67.39	67.94	70.29	66.11	52.39	56.43
1987	44.23	47.23	48.2	46.79	52.09	59	65.68	69.26	73.27	73.83	65.5	53.3	58.20
1988	43.51	45.48	49.45	45.2	47.61	56.3	60.85	64.82	70.92	75.34	70.65	57.51	57.30
1989	46.36	44.11	46.13	44.72	44.92	51.2	53.28	54.82	62.9	61.55	52.39	47.08	50.79
1990	42.41	41.79	43.08	44.94	49.76	54.63	57.06	58.81	61.53	59.52	51.33	45.15	50.83
1991	43.6	42.85	42.5	44.5	49.12	55.21	60.4	65.09	69.93	70.44	63.95	54.84	55.20
1992	47.64	44.42	44.14	46.07	49.65	53.7	58.59	62.58	64.06	61.77	54.82	46.67	52.84
1993	40.23	37.02	37.16	40.13	44.91	49.03	53.46	60.36	66.62	67.07	59.63	49.19	50.40
1994	41.31	38.62	41.26	45.72	49.24	52.62	55.56	59.52	65.04	66.51	60.54	51.17	52.26
1995	43.86	41.13	40.79	42.54	45.75	48.87	53.21	58.64	63.79	66.41	62.65	52.83	51.71
1996	43.47	38.82	38.84	41.04	44.27	49.25	54.88	59.45	61.39	60.11	53.23	44.28	49.09
1997	39.33	37.5	37.77	40.31	45.05	51.48	56.13	59.57	62.12	61.94	57.89	51.09	50.02
1998	45.84	43.49	42.47	44.38	50.08	56.51	61.6	66.12	69.14	67.44	59.46	47.61	54.51
1999	38.67	36.71	37.76	39.5	44.15	50.01	53.78	57.44	62.34	65.48	58.85	45.63	49.19
2000	38.63	37.69	38.01	40.56	45.07	49.81	54.78	58.36	59.67	57.09	49.84	41.64	47.60
2001	36.39											


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.