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Stratospheric aerosol growth and HNO 3 gas phase depletion from coupled HNO 3 and water uptake by liquid particles
Author(s) -
Carslaw K. S.,
Luo B. P.,
Clegg S. L.,
Peter Th.,
Brimblecombe P.,
Crutzen P. J.
Publication year - 1994
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/94gl02799
Subject(s) - aerosol , stratosphere , frost (temperature) , saturation (graph theory) , volume (thermodynamics) , analytical chemistry (journal) , chemistry , mineralogy , materials science , atmospheric sciences , environmental chemistry , thermodynamics , geology , organic chemistry , physics , mathematics , combinatorics , composite material
Aqueous sulphuric acid droplets, which constitute the background stratospheric aerosol, strongly absorb HNO 3 and HCl under cold conditions. A thermodynamic model is used to predict partitioning of HNO 3 , HCl and H 2 O between gas and aerosol phases, and show that a 50‐fold increase in aerosol volume, observed in the Arctic stratosphere as temperature approached the frost point (188.9 K), can be explained in terms of uptake of HNO 3 and H 2 O by liquid aerosols. Calculated degrees of saturation of the droplets with respect to solid hydrates, taking into account the reduction in vapour phase HNO 3 , suggest that the droplets remain liquid to the frost point. Near this temperature, they can yield larger aerosol volumes than would have been the case for solid NAT (HNO 3 •3H 2 O) particles. The depletion of gas phase HNO 3 into enhanced volumes of liquid aerosols resulting from volcanic eruptions may hamper NAT formation.