This study is concerned with the effect of slantwise convection in general circulation models (GCMs). The approach is through the development of a slantwise convective parameterization scheme (SCPS) and its implementation into version 11 of the third generation GCM of the Canadian Climate Centre for modelling and analysis (CCCma gcm11). / We first study the characteristics of conditional symmetric instability (CSI) in an environment which is also unstable for conditional upright instability (CUI). The results indicate features common to both upright and slantwise convection. This so called slantwise buoyant instability (SBI) possesses two relevant time scales and its horizontal scale can ranges from tens of km up to over one thousand km. / We then analyze the 15-year ECMWF re-analysis (ERA) data to compute the global distributions of convective available potential energy (CAPE) and slantwise convective available energy (SCAPE). We show that the potential for CSI and CUI indeed co-exists over most areas around the globe. Based on the results of the theoretical study and the data analysis, a parameterization for slantwise convection was developed and implemented into gcm11. It was found that the scheme impacts significantly the simulated general circulation by the development of a direct meridional secondary circulation. The results of the 5-year simulations show that the scheme reduces SCAPE and SCAPE residual rs over the mid-latitudes, leading to a weakening of the thermal wind and the strength of the upper-level jets. The largest improvement in the simulated climate however lies in the reduced meridional transient eddy transports of heat and zonal momentum. With the inclusion of the scheme, the eddy transports agree much more favorably with the observational analysis.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.37769 |
| Date | January 2000 |
| Creators | Ma, Liang, 1962- |
| Contributors | Yau, M. K. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Atmospheric and Oceanic Sciences.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001808795, proquestno: NQ70086, Theses scanned by UMI/ProQuest. |
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