HR: 17:15h
AN: A14C-05 INVITED     [Abstracts]
TI: In-cloud and Clear-sky Supersaturations with Respect to Ice at Low Temperatures in the Atmosphere
AU: * Jensen, E
EM: ejensen@cirrus.arc.nasa.gov
AF: NASA Ames Research Center, MS 245-4, Moffett Field, CA 94035 United States
AB: Recent in situ measurements in the tropical upper troposphere have documented (1) substantial (about 30%) ice supersaturations within cirrus at temperatures below about 200 K even in the presence of large ice surface areas, and (2) extremely high ice supersaturations (about 100%, near water saturation) at temperatures below about 190 K without any apparent ice nucleation. Both of these observations are unexpected and possibly indicate important cloud chemistry interactions. I will present the available evidence for supersaturations at low temperatures and discuss possible explanations involving nitric acid and organic layers on ice crystal and aerosol surfaces. I will also assess the plausibility of using remote-sensing measurements to gather statistical information about low-temperature supersaturation.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0320 Cloud physics and chemistry
DE: 0365 Troposphere--composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting