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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
341

Evaluation and 21st century projections of global climate models at a regional scale over Australia

Perkins, Sarah Elizabeth, Biological, Earth & Environmental Sciences, Faculty of Science, UNSW January 2010 (has links)
This thesis explores the ability of global climate models (GCMs) to simulate observed conditions at regional scales by examining probability density functions (PDFs) of daily minimum temperature (Tmin), maximum temperature (Tmax) and precipitation (P). Two new measures of model skill are proposed using PDFs of observed and modelled data. The first metric (Sscore) compares the amount of overlap between the two PDFs. The second metric (Tailskill) is the weighted difference between the PDF tails, where extreme events are represented. The resulting measures of skill are used to differentiate, at a regional scale, between weaker and stronger models. It is investigated whether the weaker models bias future projections given by multi-model ensembles, increasing the uncertainty in the range of projected values and the change from the 20th Century. The Sscore is demonstrated to be robust against inhomogenities found in highdensity Australian datasets, and is a simple and quantitative measure of how well each GCM can simulate all observed events. This methodology is executed for twelve Australian regions of varying climates for all Intergovernmental Panel on Climate Change 4th Assessment Report models for which daily data was available for 1961-2000. Across Tmin, Tmax and P some GCMs perform well, demonstrating that some GCMs provide credible simulations of climate at sub-continental scales. Projections of the annual and seasonal mean and yearly return values over the A2 and B1 emission scenarios are investigated. Models are omitted from an ensemble based on their ability to simulate the observed PDF at regional scales. The stronger models are generally in agreement with the change in mean values, particularly for Tmin and Tmax, though it is shown that they vary in their projections of the yearly return value at least twice as much as projections in the mean values. Lastly, a means-based evaluation method, the Sscore and the Tailskill are employed to differentiate between weaker and stronger models for projections in the 20-year return value of Tmin and Tmax. Weaker-skilled ensembles project larger increases in 20-year return values than stronger-skilled ensembles, such that in some regions for maximum temperature the ensembles are statistically significantly different. Demonstrably weaker models bias projections given by an all-model ensemble and should be excluded so the most reliable estimates of future climate can be obtained.
342

Late Cainozoic rainforest vertebrates from Australopapua: evolution, biogeography and extinction

Hocknull, Scott Alexander, Biological, Earth & Environmental Sciences, Faculty of Science, UNSW January 2009 (has links)
Understanding the evolution, biogeography and extinction of Australopapuan vertebrate lineages is fundamental to determining baseline responses of those groups to past environmental change. In light of predicted climatic change and anthropogenic impact, it is imperative to determine the trajectories of Australia???s modern flora and fauna. In particular, mesothermic rainforest faunas are among Australia???s most vulnerable terrestrial biota under threat from both natural and anthropogenic causes. There is a gap in knowledge of past patterns of change and, in particular, a conspicuous lack of direct evidence of response of rainforest faunas to past climatic change. This study documents the late Cainozoic Australopapuan rainforest vertebrate record and its response to environmental change via adaptive radiation, biogeographical change and extinction. In particular, it provides the first detailed systematic appraisal of Quaternary fossil sites and local faunas from northern Australia. The study documents the only known Quaternary mesothermic rainforest fauna in Australia and its transition to a xeric-adapted fauna during the middle Pleistocene. The fossil assemblages analysed are comprised of dozens of species, including several new genera and species. Each fossil taxon shares a close phylogenetic relationship with others either known only from the Australian Tertiary record or from Quaternary-Recent New Guinea and Wet Tropics rainforests. The presence of many species is evidence of previously much larger distributions followed by subsequent massive range retractions. Detailed documentation of this rare fauna testifies to rainforest stability in central eastern Queensland until approximately 280,000 years ago, when the development of an El Nino dominated climate generated variable climatic patterns that could not support aeseasonal rainforest. Extinction of this late Pleistocene rainforest fauna serves as one of only two examples of major rainforest faunal turnover in Cainozoic Australia, the other occurring in the late Miocene. These two major extinction events are compared. The late Pleistocene faunal extinction differs from the late Miocene event in being biased towards large-bodied, terrestrial herbivores and carnivores (both reptile and mammal). This study also combines fossil and phylogenetic data with latest understanding of palaeogeography, tectonics and sea level history along Australia???s northern margin to provide hypotheses of faunal dispersal between New Guinea and mainland Australia throughout the Neogene.
343

Spatial aggregation of vegetation parameters in a coupled land surface-atmosphere model

Arain, Muhammad Altaf. January 1994 (has links) (PDF)
Thesis (M.S. - Hydrology and Water Resources) - University of Arizona. / Includes bibliographical references (leaves 148-150).
344

Canadian vegetation response to climate and projected climatic change /

Lenihan, James M. January 1992 (has links)
Thesis (Ph. D.)--Oregon State University, 1993. / Typescript (photocopy). Includes bibliographical references (leaves 163-176). Also available online.
345

Experimental studies of cultivation of certain vegetable crops ...

Thompson, Homer Columbus, January 1927 (has links)
Thesis (Ph. D.)--Ohio state University, 1926. / Cover title. Autobiography. "Also printed as Cornell university. Agricultural experiment station. Memoir 107." "References cited": p. 69-73.
346

The vegetation-reproduction relationship in crop plants as affected by certain factors,

Pettinger, Nicholas Albert, January 1929 (has links)
Abstract of thesis (Ph. D.)--University of Illinois, 1927. / Vita. Also issued in print.
347

Amount of underground plant materials in different grassland climates

Shively, Samuel Burdette. January 1939 (has links)
Thesis (Ph. D.)--University of Nebraska, 1940. / Bibliography: p. 35-36. Also issued in print.
348

Amount of underground plant materials in different grassland climates

Shively, Samuel Burdette. January 1939 (has links)
Thesis (Ph. D.)--University of Nebraska, 1940. / eContent provider-neutral record in process. Description based on print version record. Bibliography: p. 35-36.
349

The vegetation-reproduction relationship in crop plants as affected by certain factors,

Pettinger, Nicholas Albert, January 1929 (has links)
Abstract of thesis (Ph. D.)--University of Illinois, 1927. / Vita. eContent provider-neutral record in process. Description based on print version record.
350

Experimental studies of cultivation of certain vegetable crops ...

Thompson, Homer Columbus, January 1927 (has links)
Thesis (Ph. D.)--Ohio state University, 1926. / Cover title. Autobiography. "Also printed as Cornell university. Agricultural experiment station. Memoir 107." "References cited": p. 69-73.

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