Messungen von dynamischen Tracern und Ozon in der arktischen Stratosphäre: Analyse und Interpretation flugzeuggetragener Submillimeterwellenmessungen

Abstract

The Airborne Submillimeter Radiometer (ASUR) is a passive heterodyne instrument using a superconducting detector with an instrumental frequency range from 604.3 to 662.3 GHz.Operating onboard an aircraft to avoid absorption by tropospheric water vapor key species of the stratospheric ozone chemistry can be detected for a vertical altitude range from 15 to 55 km. In the winter 1999/2000 the ASUR instrument participated in the THESEO 2000/SOLVE project onboard the NASA research aircraft DC-8. Three deployments were carried out in December 1999, January 2000, and March 2000 with 23 flights total. This last winter was one of the coldest in the last 10 years with sufficiently low temperatures for PSC formation from December 1999 until March 2000. To estimate the chemical ozone loss during the winter chemical and dynamical effects have to be separated. Four different methods have been applied to take diabatic descent into account: isentropes of constant potential temperature, heating rates calculated from ozone measurements, measurements of the dynamical tracer N:sub:2:/sub:O, as well as correlation of ozone and N:sub:2:/sub:O across the vortex edge. Also within this study diabatic descent has been calculated from ASUR N2O measurements and heating rate calculations, using ASUR ozone measurements. Finally the results have been compared to measurements performed by various instruments as well as the SLIMCAT model calculations. An important result of these investigations is that the ozone loss estimated from heating rate calculations as well as from correlation with N2O agree very good with each other. Both methods lead to a chemical loss between 30% and 40% in the lower stratosphere. Taking ASUR´s lower vertical resolution into account, these results also agree very good with sonde measurements and model calculations. The two other methods investigated, isentropes and correlations across the vortex edge tend to underestimate espectively overestimate the chemical ozone loss.