Period | Automatic ppbv, X ± σ | Passive ppbv | Differences (%) | Period | Automatic ppbv, X ± σ | Passive ppbv | Differences (%) |
January | 16.7 ± 8.2 | 17.4 | −4 | July | 12.3 ± 3.0 | 10.2 | 21 |
February | 10.8 ± 6.6 | 14.1 | −23 | August | 12.7 ± 3.5 | 14.2 | −11 |
March | 19.2 ± 4.7 | 16.7 | 15 | September | 12.4 ± 3.4 | 16.2 | −23 |
April | 25.2 ± 2.9 | 24.6 | 2 | October | 14.3 ± 2.9 | 16.9 | −15 |
May | 20.7 ± 4.7 | 19.5 | 6 | November | 23.4 ± 10.2 | 19.4 | 20 |
June | 14.9 ± 4.8 | 14.6 | 2 | December | 16.1 ± 9.4 | 15.2 | 6 |