Simulations of the 1999–2000 winter have tested the effect on polar stratospheric clouds (PSCs) of the homogeneous freezing of liquid ternary solutions into nitric acid trihydrate (NAT) and nitric acid dihydrate (NAD). Proposed laboratory-derived volume-based and surface-based homogeneous freezing rates have both been examined, including different assumptions about the extrapolation of laboratory measurements to atmospheric conditions. Widespread PSC formation and denitrification are possible in several of the scenarios examined. However, the simulations are all unable to explain the solid-phase PSCs observed early in the 1999–2000 winter and are unable to reproduce the measured extent of vortex denitrification. These problems can both be attributed to the relatively cold temperatures, more than 5 K below the NAT condensation point, necessary for homogeneous freezing to be effective at producing solid-phase PSCs. Therefore synoptic-scale homogeneous freezing appears unlikely to be the primary mechanism responsible for solid-phase PSC formation.
Microphysical modeling of the 1999--2000 Arctic winter: 3. Impact of homogeneous freezing on polar stratospheric clouds
Drdla, K., and E. Browell (2004), Microphysical modeling of the 1999--2000 Arctic winter: 3. Impact of homogeneous freezing on polar stratospheric clouds, J. Geophys. Res., 109, D10201, doi:10.1029/2003JD004352.
Abstract
PDF of Publication
Download from publisher's website
Research Program
Atmospheric Composition Modeling and Analysis Program (ACMAP)
Upper Atmosphere Research Program (UARP)
Mission
SOLVE
Disclaimer: This material is being kept online for historical purposes. Though accurate at the time of publication, it is no longer being updated. The page may contain broken links or outdated information, and parts may not function in current web browsers. Visit https://espo.nasa.gov for information about our current projects.