FATE OF MERCURY IN THE ARCTIC Michael Evan ... - COGCI

Fate of Mercury in the Arctic 69
4.1 Ozone and GEM Measurements
The results of ozone and GEM measurements for Station Nord are shown in Figure 11, page
69. It is seen that ozone is relatively stable from September/October until the end of
February/beginning of March, then a highly perturbed period occurs, where ozone and GEM are
simultaneously depleted to 0, from respectively about 40 ppbv and 1.5 ng/m 3 within hours. They
remain at 0 for up to several days when they suddenly rise again, to levels above normal ambient
levels seen in July. In July the ozone concentration stabilises slightly above 20 ppbv followed by a
slow increase to about 40 ppbv in September/October.
GEM was only measured from February to the end of July or beginning of August. The
measurements were focusing on the description of the AMDE. Previously Schroeder et al. (1998)
Ozone, ppbv
60
50
40
30
20
10
0
1999
2000
2001
Time
Ozone
GEM
1/10*fBr
Figure 11. Hourly ozone mixing ratios and weekly concentration of filterable bromine, fBr,
measured from 1999 to 2002 at Station Nord, Northeast Greenland. GEM is measured in the
period from 25 September 1999 to 23 August 2000; 14 February 2001 to 23 August 2001 and
26 April to 29 June 2002. In general the half-life of GEM at Station Nord is approximately 10
hours during AMDE. From Skov et al., 2003, submitted, Appendix C.
2002
2003
3
2
1
0
GEM,Br, ng/m 3