Increase in the PSC‐formation probability caused by high‐flying aircraft

The saturation temperature Tsat for the formation of polar stratospheric clouds (PSC) strongly depends on the local partial pressures of nitric acid and water vapour, and thus is sensitive to NOx and H2O-injection due to exhaust from aircraft in the stratosphere. The present paper investigates this effect, using daily stratospheric temperature data from the northern hemisphere compiled over the last 25 years by the Free University of Berlin. For Type-I PSC the data were examined for temperatures T < Tsat - 3 K, which would allow for a supercooling of about the 3 K measured in a previous arctic winter balloon mission, in effect corresponding to a large HNO3-supersaturation. We show that this is required to overcome the heterogeneous nucleation energy barrier. We compare the analyses of both a background atmosphere and one perturbed by a fleet of 600 stratospheric aircraft flying at ∼22 km altitude. The result is that between December and March in the polar cap region there might be more than a doubling in the occurence of Type-I PSCs and an even stronger increase of Type-II PSCs, and accordingly a substantial enhancement in the potential ozone destruction by chlorine radicals.

[1]  S. Wofsy,et al.  Denitrification in the Antarctic stratosphere , 1989, Nature.

[2]  D. Wuebbles,et al.  Nitrogen oxides from high-altitude aircraft: An update of potential effects on ozone , 1989 .

[3]  D. Golden,et al.  Reaction of Chlorine Nitrate with Hydrogen Chloride and Water at Antarctic Stratospheric Temperatures , 1987, Science.

[4]  P. Crutzen,et al.  Nitric acid cloud formation in the cold Antarctic stratosphere: a major cause for the springtime ‘ozone hole’ , 1986, Nature.

[5]  Terry Deshler,et al.  Balloonborne measurements of polar stratospheric clouds and ozone at‐93° C in the Arctic in February 1990 , 1990 .

[6]  J. Rosen.  The Boiling Point of Stratospheric Aerosols , 1971 .

[7]  H. Schlager,et al.  Balloon observations of nitric acid aerosol formation in the Arctic stratosphere: II. Aerosol , 1990 .

[8]  P. Crutzen.  Ozone production rates in an oxygen‐hydrogen‐nitrogen oxide atmosphere , 1971 .

[9]  J. Morgan,et al.  THE PROPERTIES OF MIXED LIQUIDS. I. SULFURIC ACID-WATER MIXTURES. , 1916 .

[10]  H. Schlager,et al.  Balloon observations of nitric acid aerosol formation in the Arctic stratosphere: I. Gaseous nitric acid , 1990 .

[11]  H. Johnston.  Reduction of Stratospheric Ozone by Nitrogen Oxide Catalysts from Supersonic Transport Exhaust , 1971, Science.

[12]  M. Molina,et al.  Production of Cl2O2 from the self-reaction of the ClO radical , 1987 .

[13]  M. Molina,et al.  Antarctic Stratospheric Chemistry of Chlorine Nitrate, Hydrogen Chloride, and Ice: Release of Active Chlorine , 1987, Science.

[14]  R. Turco,et al.  Denitrification mechanisms in the polar stratospheres , 1990 .

[15]  S. Wofsy,et al.  Nucleation and Growth of HNO3.3H2O Particles in the Polar Stratosphere , 1990 .

[16]  J. Bacmeister,et al.  Small‐scale waves encountered during AASE , 1990 .

[17]  David R. Hanson,et al.  Laboratory studies of the nitric acid trihydrate: Implications for the south polar stratosphere , 1988 .

[18]  D. Fahey,et al.  Observations of denitrification and dehydration in the winter polar stratospheres , 1990, Nature.

[19]  R. Turco,et al.  Physical processes in polar stratospheric ice clouds , 1989 .

[20]  R. Turco,et al.  Condensation of HNO3 and HCl in the winter polar stratospheres , 1986 .