Measurements of arctic sunrise surface ozone depletion events at Kangerlussuaq, Greenland (67°N, 51°W)

In situ measurements of surface ozone were conducted from 30 January through 22 May 1995, at the Sondrestrom Incoherent Scatter Radar Facility near Kangerlussuaq, Greenland. Several periods of depleted ozone were observed, representing the lowest latitude measurements of springtime surface polar ozone depletion in the northern hemisphere to date. The most severe ozone depletion occurred during 14-17 March, when surface ozone levels abruptly fell to below 10 ppbv from typical values of about 40 ppbv. Simultaneous near-ultraviolet and visible total column spectroscopic measurements were made with ground-based instruments, yielding total column values for BrO and OClO. Elevated levels of BrO were observed at the onset of ozone depletion episodes and the behaviour of BrO slant column values through the morning twilight of 15 March indicated that the BrO column must reside in the boundary layer. The boundary layer BrO mixing ratio was estimated at greater than 13 pptv during this episode. OClO levels showed no correlation with surface ozone depletion nor clear evidence of a large tropospheric burden.