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

Lily Zhang,Natalya Kramarova,Susan Solomon,Steve Colwell,Catherine Wilka,Jonathan Shanklin,Paul Newman,Mark Weber,Anna Jones,David Haffner,Joshua Eveson,John Burrows,Pieternel Levelt,Gordon Labow,Kane Stone

doi:10.5194/egusphere-egu21-13012

Abstract

&lt;p&gt;Measurements by the Dobson ozone spectrophotometer at the British Antarctic Survey&amp;#8217;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 for eight months and [SC-UB1]&amp;#160; led to a gap in its historic record. &amp;#160;We develop and test a method for filling in the record of Halley total ozone by combining and bias-correcting 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 20 Dobson units.&amp;#160; We show that our approach improves on the overall performance as compared to simply using the raw satellite average or an individual instrument. The method also provides a check on the consistency of the automated Dobson used at Halley after 2018 compared to earlier manual Dobson data, and suggests a significant difference between the two.&amp;#160; The filled Halley dataset provides further support that the Antarctic ozone hole is healing not only during September, but also in January.&lt;/p&gt;

Highlights

Using the Halley Dobson record, Farman et al (1985) were the first to identify the austral springtime Antarctic ozone hole, a discovery that would change the fundamental scientific understanding of atmospheric ozone chemistry and contribute to environmental policy at the international level via the Montreal Protocol (Birmpili, 2018)
The average of all satellite instruments consistently performs well relative to the individual instruments in all months except April and in particular during the austral spring months of August, September, and October
We developed a method to fill in missing data in the historic Halley record of total ozone (Farman et al, 1985; Jones and Shanklin, 1995) using satellite overpass data, with a particular focus on the period of 2017–2018 when the Halley station was abruptly closed for safety reasons associated with a crack in the ice shelf

Summary

Introduction

Using the Halley Dobson record, Farman et al (1985) were the first to identify the austral springtime Antarctic ozone hole, a discovery that would change the fundamental scientific understanding of atmospheric ozone chemistry and contribute to environmental policy at the international level via the Montreal Protocol (Birmpili, 2018). The length of the Halley Dobson record as well as the Halley station’s particular location relative to the polar vortex and solar terminator have made it historically important and uniquely valuable to modern studies of Antarctic total ozone. No ozone data were taken during the austral springs of 2017 or 2018, breaking the continuity of this unique record of the springtime ozone hole.

Objectives

Methods

Results

Conclusion