| dc.contributor.author | Boudala, Faisal. | en_US |
| dc.date.accessioned | 2014-10-21T12:38:48Z | |
| dc.date.available | 2004 | |
| dc.date.issued | 2004 | en_US |
| dc.identifier.other | AAINQ89797 | en_US |
| dc.identifier.uri | http://hdl.handle.net/10222/54602 | |
| dc.description | Using cloud microphysical data collected in extra-tropical stratiform clouds, parameterizations of the mean effective size (Dge) and size distribution of ice crystals for ice clouds, and cloud phase fraction in terms of temperature and cloud water contents have been developed. The climate implications of the new Dge parameterizations have been tested using the Canadian Centre for Climate Modeling and Analysis (CCCma) general circulation model (GCM). | en_US |
| dc.description | Four different schemes used to convert ice particle spectra into ice water content (IWC), based on PMS 2D-C and 2D-P probes measurements, have been tested against direct measurements of IWC. It has been found that the IWC derived using the Cunningham (1978) coefficients correlated well with observations. | en_US |
| dc.description | Small ice particles (L < 100mum) (SIP) are estimated using ice concentrations and spectra measured with the PMS FSSP and 2D-C probes respectively. After adding the mass of SIP, the total derived ice mass using the Cunningham's coefficients matched well with observations. Microphysical analysis of all the data collected in glaciated clouds indicates that the SIP contribute 43% to the total cross-sectional area (Ac) and 23% to the total IWC. Since Dge is directly proportional to the ratio, IWC/Ac, the addition of SIP reduced the derived Dge. The largest reduction in D ge occurs at the coldest temperature and low IWC. The CCCma GCM simulation also indicates that both longwave and shortwave cloud forcing increase with decreasing Dge. | en_US |
| dc.description | Using a gamma distribution function for SIP mentioned earlier, and assuming that the large ice particles (L > 100mum) have an exponential distribution, bi-modal size distributions of ice particles as a function of IWC and temperature have been developed. This parameterization agrees well with observation. | en_US |
| dc.description | Using in-situ data, it has been found that the liquid fraction has a strong minimum near -15°C where a maximum in ice crystal growth rate is expected. Using a newly developed bulk microphysics scheme, the evolution of mixed-phase cloud and the sensitivity to small ice particles, temperature, and total water content (TWC) have been explored based on a single prognostic equation developed by Tremblay et al. (1996). One of the important results obtained from this modeling study is that the addition of SIP significantly increases the vapor deposition rate which makes the cloud unstable (glaciates quickly) in a water saturated atmosphere, particularly at low updraft velocities. | en_US |
| dc.description | Thesis (Ph.D.)--Dalhousie University (Canada), 2004. | en_US |
| dc.language | eng | en_US |
| dc.publisher | Dalhousie University | en_US |
| dc.publisher | | en_US |
| dc.subject | Physics, Atmospheric Science. | en_US |
| dc.title | Parameterization of ice crystal properties and liquid fraction in extra-tropical stratiform clouds. | en_US |
| dc.type | text | en_US |
| dc.contributor.degree | Ph.D. | en_US |
