A study of polar ozone depletion based on sequential assimilation of satellite data from the ENVISAT/MIPAS and Odin/SMR instruments

摘要

The objective of this study is to demonstrate how polar ozone depletion canbe mapped and quantified by assimilating ozone data from satellites into thewind driven transport model DIAMOND, (Dynamical Isentropic Assimilation Modelfor OdiN Data). By assimilating a large set of satellite data into atransport model, ozone fields can be built up that are less noisy than theindividual satellite ozone profiles. The transported fields can subsequentlybe compared to later sets of incoming satellite data so that the rates andgeographical distribution of ozone depletion can be determined. By tracingthe amounts of solar irradiation received by different air parcels in atransport model it is furthermore possible to study the photolytic reactionsthat destroy ozone.In this study, destruction of ozone that took place in the Antarctic winterof 2003 and in the Arctic winter of 2002/2003 have been examined byassimilating ozone data from the ENVISAT/MIPAS and Odin/SMRsatellite-instruments. Large scale depletion of ozone was observed in theAntarctic polar vortex of 2003 when sunlight returned after the polar night.By mid October ENVISAT/MIPAS data indicate vortex ozone depletion in theranges 80–100% and 70–90% on the 425 and 475 K potential temperaturelevels respectively while the Odin/SMR data indicates depletion in the ranges70–90% and 50–70%. The discrepancy between the two instruments has beenattributed to systematic errors in the Odin/SMR data.Assimilated fields of ENVISAT/MIPAS data indicate ozone depletion in therange 10–20% on the 475 K potential temperature level, (~19 kmaltitude), in the central regions of the 2002/2003 Arctic polar vortex.Assimilated fields of Odin/SMR data on the other hand indicate ozonedepletion in the range 20–30%.