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Balloonborne backscatter observations of type 1 PSC formation: Inference about physical state from trajectory analysis
Author(s) -
Larsen Niels,
Knudsen Bjørn M.,
Rosen James M.,
Kjome Norman T.,
Kyrö Esko
Publication year - 1996
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 - 10.1029/96gl01041
Subject(s) - backscatter (email) , nat , supercooling , settling , frost (temperature) , condensation , polar , cloud condensation nuclei , materials science , atmospheric sciences , mineralogy , thermodynamics , physics , chemistry , meteorology , telecommunications , quantum mechanics , astronomy , computer science , wireless , aerosol
Ballonborne backscatter measurements of polar stratospheric clouds (PSC) from four Arctic winters have been used together with isentropic airparcel trajectories to assess recent theories of PSC formation. Assuming unperturbed HNO 3 concentrations, observations performed in the month of January, reveal that PSC formation initiates 3–4 K below the nitric acid trihydrate (NAT) condensation temperature (T NAT ). According to a suggested scenario for PSC formation [ Tabazcdeh et al. , 1995] liquid supercooled ternary solution particles may freeze upon an increase in temperature after previously being close to the ice frost point. Liquid particles, identified by the temperature histories according to this scenario, show a relatively compact relationship between measured temperature and backscatter ratio, indicating a substantial growth at 3–4 K below the NAT‐temperature as expected by ternary solution particles. Newly formed solid particles are of small size, in contrast to aged solid particles which appear to retain large sizes up to the NAT‐temperatures during evaporation and grow by condensation at temperatures slightly below T NAT , indicating the composition to be NAT.