Since 1950, the West African Sahel has exhibited unusual multi-decadal persistence in rainfall anomalies. Wet conditions were prevalent in the 1950s while drought has existed since the late 1960s. The Kalahari, the southern hemisphere counterpart to the Sahel, has not demonstrated any persistence longer than three or four years. It has been hypothesized that large-scale phenomena initiate drought while land surface-atmosphere feedbacks perpetuate it. / To approach this theory, an updated version of Lettau's three-part climatonomy model is used. Using incoming solar radiation and observed precipitation, the model calculates ground-absorbed solar radiation, evapotranspiration, soil moisture, runoff, all surface radiation and energy balance fluxes, as well as surface and atmospheric temperatures. A typical Sahelian station was used to revise and verify the model. The model was then applied to mean conditions at several stations of various climatic types in West Africa and Southern Africa. Mean hydrologic and surface energy budget parameters between wet and dry years were compared. Finally, model output was used to derive spatial fields of hydrologic and surface energy parameters for both the Sahel and the Kalahari and to approximate the effect of surface energy flux modification upon mid-tropospheric wind dynamics. / Several interesting results emerge from these simulations. Significant modification of latent and sensible heat has occurred over the Sahel since 1950, more so than in the Kalahari. It has also been shown through thermal wind calculations that latent heat flux changes have altered the strength of the Africa Easterly Jet, and hence, possibly the rain bearing systems as well. / Source: Dissertation Abstracts International, Volume: 53-07, Section: B, page: 3541. / Major Professor: Sharon E. Nicholson. / Thesis (Ph.D.)--The Florida State University, 1992.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_76707 |
| Contributors | Lare, Andrew Robert., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 355 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
Page generated in 0.0017 seconds