Analysis of SOLVE Observations of PSCs and Implications for the Evolution of the Arctic Vortex

摘要

In-situ measurements of polar stratospheric clouds (PSCs) made from the ER-2 aircraft during the SAGE III Ozone Loss and Validation Experiment (SOLVE) have revealed new information about the composition and properties of these clouds. Model results have been compared with the ER-2 measurements in order to refine understanding of the cloud microphysics. Measurements made by the Multiangle Aerosol Spectrometer Probe (MASP) reveal that most particles generally appear to be liquid-phase. Growth of these particles was observed at temperatures near 192 kelvin (K), consistent with the predicted behavior of ternary nitric acid/dihydrogen sulfate/water solutions (HNO3/H2SO4/H2O). Even at warmer temperatures. starting as air cools below 196 K. some swelling of the particles is apparent. The correlation of this growth with total available HNO3, indicates that HNO3 condensation is responsible. The observations have been compared with predictions of several ternary solution models with generally good agreement. The presence of liquid-phase particles has implications for the long-term evolution of the Arctic winter. The widespread persistence of liquid particles constrains understanding of freezing processes. especially in air parcels that have experienced extensive denitrification. No significant differences in particle size distributions exist between highly denitrified and less denitrified air parcels. suggesting that very few particles are removed by the processes causing denitrification.