Observations and analysis of polar stratospheric clouds detected by POAM III and SAGE III during the SOLVE II/VINTERSOL campaign in the 2002/2003 Northern Hemisphere winter

摘要

The Polar Ozone and Aerosol Measurement and Stratospheric Aerosol and GasExperiment instruments both observed high numbers of polar stratosphericclouds (PSCs) in the polar region during the second SAGE Ozone Loss andValidation (SOLVE II) and Validation of INTERnational Satellites and Studyof Ozone Loss (VINTERSOL) campaign, conducted during the 2002/2003 NorthernHemisphere winter. Between 15 November 2002 (14 November 2002) and 18 March2003 (21 March 2003) SAGE (POAM) observed 122 (151) aerosol extinctionprofiles containing PSCs. PSCs were observed on an almost daily basis, fromearly December through 15 January, in both instruments. No PSCs wereobserved from either instrument from 15 January until 4 February, and fromthen only sparingly in three periods in mid- and late February and mid-March.In early December, PSCs were observed in the potential temperature rangefrom roughly 375 K to 750 K. Throughout December the top of this rangedecreases to near 600 K. In February and March, PSC observations wereprimarily constrained to potential temperatures below 500 K. The PSCobservation frequency as a function of ambient temperature relative to thenitric acid-trihydrate saturation point (using a nitric acid profile priorto denitrification) was used to infer irreversible denitrification. By lateDecember 38% denitrification was inferred at both the 400–475 K and475–550 K potential temperature ranges. By early January extensive levels ofdenitrification near 80% were inferred at both potential temperatureranges, and the air remained denitrified at least through early March.