Role of the Stratospheric Polar Freezing Belt in Denitrification

• Published in: Science (American Association for the Advancement of Science) Vol. 291; no. 5513; pp. 2591 - 2594
• Main Authors: Tabazadeh, A., Jensen, E. J., Toon, O. B., Drdla, K., Schoeberl, M. R.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for the Advancement of Science 30.03.2001; American Association for the Advancement of Science; The American Association for the Advancement of Science
• Subjects: Acids; Altitude; Analysis; Antarctica; Arctic; Atmospheric composition. Chemical and photochemical reactions; Causes of; Chemistry; Climate; Clouds; Earth, ocean, space; Exact sciences and technology; External geophysics; Freezing; Hydrates; Meteorology; Mixing ratios; Nucleation; Organic Chemistry; Ozone; Ozone layer depletion; Particle density; Particle production; Physics of the high neutral atmosphere; Regions; Science and Society; Stratosphere; Temperature; Antarctica; Arctic Region; Arctic region; PN, Arctic; Winter; Polar stratospheric cloud; Denitrification; Stratosphere; Numerical simulation; Polar region; Freezing; Nitric acid; Hydrates; Altitudinal distribution
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1057228

Homogeneous freezing of nitric acid hydrate particles can produce a polar freezing belt in either hemisphere that can cause denitrification. Computed denitrification profiles for one Antarctic and two Arctic cold winters are presented. The vertical range over which denitrification occurs is normally quite deep in the Antarctic but limited in the Arctic. A 4 kelvin decrease in the temperature of the Arctic stratosphere due to anthropogenic and/or natural effects can trigger the occurrence of widespread severe denitrification. Ozone loss is amplified in a denitrified stratosphere, so the effects of falling temperatures in promoting denitrification must be considered in assessment studies of ozone recovery trends.