Atmospheric Chemistry and Physics (Jan 2004)

Investigation of Arctic ozone depletion sampled over midlatitudes during the Egrett campaign of spring/summer 2000

  • D. E. M. Ross,
  • D. E. M. Ross,
  • J. A. Pyle,
  • J. A. Pyle,
  • N. R. P. Harris,
  • N. R. P. Harris,
  • J. D. McIntyre,
  • G. A. Millard,
  • A. D. Robinson,
  • R. Busen

Journal volume & issue
Vol. 4, no. 5
pp. 1407 – 1417

Abstract

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A unique halocarbon dataset has been obtained using the Australian high altitude research aircraft, the Grob G520T Egrett, during May-June 2000 with GC instrument (DIRAC), which has been previously deployed on balloon platforms. The halocarbon data generally shows a good anticorrelation with ozone data obtained simultaneously from commercial sensors. On 5 June 2000, at 380K, the Egrett entered a high latitude tongue of air over the U.K. CFC-11 and O3 data obtained on the flight show evidence of this feature. The dataset has been used, in conjunction with a 3D chemical transport model, to infer ozone depletion encountered in the midlatitude lower stratosphere during the flight. We calculate that ozone is depleted by 20% relative to its winter value in the higher latitude airmass. A suite of ozone loss tracers in the model have been used to track ozone depletion according to location relative to the vortex and chemical cycle responsible. The model, initialised on 9 December, indicates that 50% of the total chemical ozone destruction encountered in June in the middle latitudes occurred in the 90-70°N equivalent latitude band and that 70% was due to halogen chemistry.