HR: 15:15h
AN: A33E-07    [Abstracts]
TI: The PDFs of microphysical parameters obtained from mixed phase cloud systems
AU: * Gultepe, I
EM: ismail.gultepe@ec.gc.ca
AF: Environment Canada Cloud Physics and Severe Weather Res. Div., 4905 Dufferin St. , Toronto, ONT M3H5T4 Canada
AB: The present study analyzes measurements of cloud microphysical parameters collected during the Alliance Icing Research Study (AIRS) field programs to obtain probability density functions (PDFs) for modeling studies. Observations from the three AIRS field programs were obtained over southern Ontario and Quebec during the winters of 1999-2000, 2003, and 2003-2004. Earlier studies have either assumed theoretical size distributions (e.g. triangle PDFs) or Gaussian distributions based on model simulations; therefore, they have not been tested extensively for mixed phase clouds. The present work uses 1-s aircraft observations to obtain PDFs representing 0.1, 10, and 50 km scales at 10(°)C intervals between +10(°)C and -40(°)C temperature levels. The main parameters used in this analysis are vapor mixing ratio (qv), total condensed water content (TCWC), liquid water content (LWC), ice water content (IWC), and total water content (TWC). The TWC is obtained by adding qv to TCWC. Hot-wire probes were used to measure LWC and TCWC, and either the EG&G or LiCor Hygrometer was used to measure qv. IWC is obtained as the difference between TCWC and LWC and it may include large uncertainties because of sensitivity problems. The results show that qv and TWC distributions can be represented with lognormal and gamma PDFs; however, LWC, IWC, and TCWC distributions can be better represented by 2 parameter gamma or beta PDFs. Also, the coefficients obtained for PDFs are found to be both temperature and scale dependent. It is concluded that PDFs cannot be fixed for all cloud types and model scales.
DE: 0320 Cloud physics and chemistry
DE: 0321 Cloud/radiation interaction
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005