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

[摘要] A unique halocarbon dataset has been obtained using the Australian highaltitude research aircraft, the Grob G520T Egrett, during May-June 2000 withGC instrument (DIRAC), which has been previously deployed on balloonplatforms. The halocarbon data generally shows a good anticorrelation withozone data obtained simultaneously from commercial sensors. On 5 June2000, at 380K, the Egrett entered a high latitude tongue of air over theU.K. CFC-11 and O₃ data obtained on the flight show evidence of thisfeature. The dataset has been used, in conjunction with a 3D chemicaltransport model, to infer ozone depletion encountered in the midlatitudelower stratosphere during the flight. We calculate that ozone is depleted by20% relative to its winter value in the higher latitude airmass. A suiteof ozone loss tracers in the model have been used to track ozone depletionaccording to location relative to the vortex and chemical cycle responsible.The model, initialised on 9 December, indicates that 50% of thetotal chemical ozone destruction encountered in June in the middle latitudesoccurred in the 90-70°N equivalent latitude band and that 70%was due to halogen chemistry.

[学科分类] 大气科学