The Gulf of Mexico and Caribbean Sea comprise a sensitive and important region, both oceanographically and climatically. A better understanding of the history of climate and marine environmental conditions in this region provides valuable insight into the processes that affect climate globally. This dissertation furthers our understanding of these factors via investigations of the isotopes of corals and seawater, as well as coral growth. Results improve our understanding of how the isotope and coral growth records from the Gulf of Mexico and Caribbean Sea reflect recent environmental conditions, enhancing our ability to reconstruct the history of climate in this important region. Analysis of the relationship between salinity and oxygen isotopic composition of seawater from the Texas/Louisiana continental shelf and Flower Garden Banks yield improved understanding of the relative contribution of the fresh water sources into the northern Gulf of Mexico, and also the oxygen isotopic composition of open-ocean seawater in this region. Variations in the growth of long-lived coral cores from the Flower Garden Banks are compared to local and regional climate conditions, particularly winter air temperatures. During the latter half of the twentieth century, a close correlation has existed between slow coral growth and cold wintertime air temperatures along the Gulf Coast, which are due to a meridional orientation of the North American jet stream (associated with the Pacific/North American climate pattern). Existing long coral growth records are too limited to assess this relationship during earlier years. Knowledge of the marine radiocarbon (14C) reservoir age is important for understanding carbon cycling and calibrating the radiocarbon ages of marine samples. Radiocarbon concentrations in corals from the Flower Garden Banks, Veracruz, and the Cariaco Basin are measured and used to determine the surface ocean 14C reservoir ages for the Gulf of Mexico and Caribbean Sea. Results also indicate that the post-nuclear weapons testing Delta 14-C values of the Gulf of Mexico and Caribbean Sea differ. This difference is attributed to the advection of 14C-depleted surface water from the Southern Hemisphere into the Caribbean Sea. The results reported in this dissertation provide valuable information for understanding the marine environment when using carbonate proxies to study and reconstruct past climate and marine conditions in the Gulf of Mexico and Caribbean.

A drip type rainfall simulator and an existing watershed study were used to assess relationships between runoff, infiltration, erosion and associated risk thresholds on a range watershed in Brazos County, Texas. The focus of the research was determining erosion risk associated with seasonal variations in precipitation and vegetation. The objectives were to (1) develop a climatic profile for Brazos County, Texas, (2) evaluate relationships between vegetative cover, infiltration, runoff, and climatic events, (3) quantify erosion/ runoff risk associated with measured vegetation, soil moisture, and climatic events, and (4) identify potential managerial thresholds for erosion risk management on similar range watersheds. The current year climatic profile showed the wettest season was summer with thirty-two percent of the precipitation coming from one rainfall event. Also, October through December was higher than the long-term rainfall average. Pair wise correlations identified season, initial time to runoff, percent litter, annual as the dominant species, soil moisture, amount to runoff and amount to storage as significant (p<0.05) variables affecting runoff and infiltration. Percent saturation and annuals as the dominant species were significant variables affecting sediment yield. During the current study, seasonal variations in precipitation patterns influenced runoff, infiltration, and sediment yield. Spring and summer had the highest infiltration rates while the largest runoff events were in fall and winter. The highest percent of soil saturation coincided with the largest runoff and sediment losses. Minimums of two centimeters (winter and fall) and three centimeters (spring and summer) initiated runoff. This rainfall threshold would be exceeded 20 percent of the time based on the climatic profile developed for Brazos County. Peak biomass production for the watershed site was 170.61 g/m2. This was above the recommended biomass threshold of 134.5 to 168.1 grams/m2 to minimize sediment loss for tallgrass rangeland. Annual sediment loss was 10.8 grams/m2, which is negligible. Additional research across a wider array of site variation is needed to identify appropriate thresholds for the Post Oak Savanna ecosystem.

This dissertation aims at understanding ocean-atmosphere interactions in the Atlantic basin, and how this coupling may lead to increased climate predictability on seasonal-to-interannual time scales. Two regions are studied: the South Atlantic convergence zone (SACZ), and the tropical Atlantic. We studied the SACZ during austral summer and separated its variability into forced and internal components. This was done by applying a signal-to-noise optimization procedure to an ensemble of integrations of the NCAR Community Climate Model (CCM3)forced with observed Sea Surface Temperature (SST). The analysis yielded two dominant responses: (1) a response to local Atlantic SST consisting of a dipole-like structure in precipitation close to the coast of South America; (2) a response to Pacific SST which manifests mainly in the upper-level circulation consisting of a northeastward shift of the SACZ during El Niño events. The land portion of the SACZ was found to be primarily dominated by internal variability, thereby having limited potential predictability at seasonal time scales. We studied two aspects of tropical Atlantic Variability (TAV). First, we investigated the effect of extratropical variability on the gradient mode. We found that the intensive Southern Hemisphere (SH) winter variability can play a pre-conditioning role in the onset of the interhemispheric anomalies in the deep tropics during boreal spring. This SH influence on TAV is contrasted with its northern counterpart that primarily comes from the North Atlantic Oscillation during boreal winter. Second, we explored the importance of ocean dynamics in the predictability of TAV. We used the CCM3 coupled to a slab ocean as a tier-one prediction system. The ocean processes are included as a statistical correction that parameterizes the heat transport due to anomalous linear ocean dynamics. The role of ocean dynamics was studied by comparing prediction runs with and without the correction. We showed that in the corrected region the corrected model outperforms the non-corrected one particularly at long lead times. Furthermore, when the model was initialized with global initial conditions, tropical Atlantic SST anomalies are skillfully predicted for lead times of up to six months. As result, the corrected model showed high skill in predicting rainfall in the ITCZ during boreal spring.

This study hopes to discuss the relationship among the sense of humor, organization playfulness climate and job¡¦s satisfaction. It¡¦s taken 30 organizations in Taiwan and the effective volume was 1,213, the returns-ratio reached 95.21%. We will use HLM (hierarchical linear model) to analyze the data instead of the regression analysis in tradition. The major result of this study are as following¡G 1. Sense of humor has a significant effect on job¡¦s satisfaction. 2. Organization playfulness climate a significant effect on job¡¦s satisfaction. 3. Organization playfulness climate has no moderate effect on sense of humor and job¡¦s satisfaction.

Thesis (M.A.)--University of Hong Kong, 2009. / Includes bibliographical references (p. 72-87).

Thesis (Ph. D.)--University of Queensland, 2003. / Includes bibliographical references.

Thesis (M.S.) in Geological Sciences--University of Maine, 2001. / Includes vita. Includes bibliographical references (leaves 205-214).

<p> The empirical analysis in this dissertation comprises two essays investigating the impacts of climate change on agriculture in Morocco, with an emphasis on climate uncertainty and robust adaptation.</p><p> The first essay in Chapter 4 provides estimates of economic impacts of climate change, and estimates on the extent to which the current Moroccan agricultural development and investment strategy, the Plan Maroc Vert (PMV), could help in agricultural adaptation to climate change and uncertainty.</p><p> We simulated three cases. First, we examined the impacts of PMV on the economy in the absence of climate change and found that it could provide about a 2.4% increase in GDP if the targets could be achieved. Subsequently, we did a separate simulation of the impacts of climate change on the Moroccan economy with no PMV (CC-Only) and found that there would be negative GDP impacts ranging between -0.5% and -3% depending on the climate scenario under the without CO₂ case. Including CO₂ fertilization effects induces a slight change in the distribution of impacts, which range from -1.4% to +0.3%. Finally, we evaluated the extent to which PMV could help mitigate the adverse impacts of climate change, and we found that the gain was quite small ranging between +0.02% and +0.04%.</p><p> The ability of the PMV strategy to mitigate the negative effects of climate change is limited at best, if non-existent. This is due to the scope of the PMV simulations limited to the strategic agricultural crop sectors in Morocco, which jointly represent no more than 35% of aggregate agricultural GDP; whereas the rest of the sectors account for 65%. Additionally, the likelihood of meeting the PMV productivity targets is low in light of our benchmark analysis comparing productivity prior to and after the adoption of GMO technologies.</p><p> The second essay examines the interaction of globalization through trade liberalization and climate change. Our hypothesis was that the more trade is liberalized, the higher the potential to compensate for losses due to climate change.</p><p> Our findings suggest that at the global level, our hypothesis is verified. World welfare gains are highest under a multilateral trade liberalization scenario, which induces a total offset of climate change welfare losses. However, under partial trade liberalization, the welfare gains become very small in comparison with the climate change impacts.</p><p> At the regional level, the results are more nuanced and our hypothesis does not hold for all regions. For instance, and focusing on Morocco as a case study, the net welfare impacts associated with trade liberalization are negative on average. But under the multilateral trade liberalization scenario, Morocco experiences net welfare gains under the SRES A1B and B1, which respectively reached US$ +23 million and US$ +16 million. Although trade liberalization induces net allocative efficiency gains under most scenarios, the large negative terms of trade effects offset most of the gains.</p>

<p> The Urban Heat Island (UHI) was investigated using satellite data, ground observations, and simulations with an Urban Canopy Parameterization in a numerical weather prediction model. Satellite-observed surface skin temperatures at Xi'an City and Oklahoma City (OKC) were analyzed to compare the UHI intensity for the two inland cities. A larger population density and larger building density in Xi'an City creates a stronger skin-level UHI effect. However, ground observed 2-m surface air temperature (Tair) data showed an urban cooling island (UCI) effect that occurred over an urban region in OKC during the daytime of July 19, 2003. </p><p> The sensitivity and accuracy of an Urban Canopy Model were evaluated by comparing simulation results between the urban and rural areas of OKC. The model reproduced skin temperature differences between the rural and urban area and reproduced a UCI effect in OKC. Furthermore, the Weather Research and Forecasting (WRF)/Noah/Single-Layer Urban Canopy Model (SLUCM) simulations were also compared with ground observations, including wind speeds, wind directions, and energy fluxes. Although the WRF/SLCUM model failed to simulate these variables accurately, it reproduced the diurnal variations of surface temperatures, wind speeds, wind directions and energy fluxes reasonably well.</p>

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.