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On the Use of Satellite Observations to Fill Gaps in the Halley Station Total Ozone Record

L.N. Zhang1, S. Solomon1, K.A. Stone1, J.D. Shanklin2, J.D. Eveson2, S. Colwell2, J.P. Burrows3, M. Weber3, P.F. Levelt4,5, N.A. Kramarova6 and D.P. Haffner6

1Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, Cambridge, MA; 617-949-9385, E-mail: lnz0018@gmail.com
2British Antarctic Survey, Cambridge, United Kingdom
3Institute of Environmental Physics, University of Bremen, Bremen, Germany
4Royal Netherlands Meteorological Institute (KMNI), De Bilt, Netherlands
5University of Technology Delft, Delft, Netherlands
6NASA Goddard Space Flight Center (GSFC), Greenbelt, MD 20771

Measurements by the Dobson ozone spectrophotometer at the British Antarctic Survey’s (BAS) Halley research station form a record of Antarctic total column ozone that dates back to 1956. Due to its location, length, and completeness, the record has been, and continues to be, uniquely important for studies of long-term changes in Antarctic ozone. However, a crack in the ice shelf on which it resides forced the station to abruptly close, leading to a gap of two ozone hole seasons in its historic record. We develop and test a method for filling in the record of Halley total ozone by combining and adjusting overpass data from a range of different satellite instruments. Tests suggest that our method reproduces the monthly ground-based Dobson total ozone values to within an average of 2 Dobson units. We show that our approach improves on the overall performance as compared to simply using the raw satellite average or data from a single satellite instrument. The method also provides a check on the consistency of the provisional data from the automated Dobson used at Halley after 2018 with earlier manual Dobson data, and suggests that there was a significant difference between the two. The filled Halley dataset provides further support that the Antarctic ozone hole is healing, not only during September, but also in January.

Figure 1

Figure 1. Total column ozone measurements by Dobson instruments at Halley station (in black) overlaid on top of the available satellite measurements (in red) from 2014-2019.

Figure 2

Figure 2. Monthly Halley ozone averages over time (black) for (a) September and (b) January, with the delta-adjusted satellite average (red) filled in for years with no or provisional Halley Dobson observations. Note that GOME and SBUV data are not yet available.