<p> With more than half of the world's population living in urban areas, it is important that the relationships between the urban environment and climate are better understood. The current research aims to continue the effort in assessing and understanding the urban environment through the use of a global climate model (GCM). Given the relative newness of the presence of an urban land type and model in a GCM, there are many more facets of the urban-climate relationship to be investigated. By comparing thirty-year ensembles of CAM4 coupled with CLM4 both with (U) and without (U_n) the inclusion of the urban land type, the sensitivity of the atmospheric model to urban land cover is assessed. As expected, largest differences tend to be in the Northern Hemisphere due to the location of most of the globe's densest and expansive cities. Significant differences in the basic climate variables of temperature and precipitation are present at annual, seasonal, and monthly scales in some regions. Seasonality to the urban influence also exists with the transition months of Spring and Fall having the largest difference in temperatures. Of the eleven regions defined by Oleson (2012), three were most impacted by the presence of urban land cover in the model&mdash;Europe, Central Asia, and East Asia. </p><p> Since urban attributes can vary greatly within one world continent, the sensitivity of regional climates to the urban type parameters is also explored. By setting all urban land cover to only one urban density type, the importance of city composition on climate, even within the same city, is highlighted. While preserving the distinct urban regional characteristics and the geographical distribution of urbanized areas, the model is run with homogeneous urban types: high density and tall building district. As with the default urban and excluded urban runs, a strong seasonality to the differences between the solo-high-density simulation and default urban (U_HD &ndash; U) and solo-tall-building-district-density simulation and default urban (U_TBD &ndash; U) exists. Overall, the transition and winter months are most sensitive to changes in urban density type.</p>

This dissertation investigates three topics concerning high clouds: 1) convectively coupled equatorial wave (CCEW) signals derived from cloud top temperature (CTT) and cirrus optical thickness retrieved from satellite observations; 2) investigation of the physical mechanism governing the fixed anvil temperature (FAT) hypothesis and test of FAT hypothesis with CTT measurements; and 3) the intercomparison of cloud fraction and radiative effects between satellite-based observations and reanalysis product and simulations from general circulation models (GCMs). A wealth of information on CCEWs is derived from Aqua/MODIS cloud-top properties. We apply space-time spectral analysis on more than 6 years of CTT and isolate various modes of CCEWs including Kelvin, n = 1 equatorial Rossby, mixed Rossby-gravity, n = 0 eastward inertio-gravity waves, and the Madden-Julian oscillation. The successful application of the same method to cirrus cloud optical thickness confirms robust convective signals at upper troposphere. Consistent with the physical governing mechanism of the FAT hypothesis, the peak clear-sky diabatic subsidence, convergence and cloud fraction are located at roughly the same level (200 hPa), which is fundamentally determined by the rapid decrease of water vapor concentration above this level. The geographical maxima of cloud fraction agree well with that of water vapor, clear-sky cooling rates, diabatic subsidence and convergence at 200 hPa. An analysis of the response of the tropical mean CTT anomaly time series to sea surface temperature indicates that a possible negative relationship is present. In addition, we suggest interpreting the FAT hypothesis, and the more recent proportionately higher anvil temperature (PHAT) hypothesis, by using the temperature at the maximum cloud detrainment level instead of the CTT. Simulations of cloud fraction and radiative properties using two versions of the NCAR CAM models indicate that an overall improvement is observed in CAM5 compared to CAM3. However, an apparent bias in CAM5 shortwave (SW) cloud radiative forcing (CRF) simulation is shown in boreal winter southern mid latitude. This bias is primarily due to the underestimation of fraction-weighted SW CRF related to both high and middle top clouds. Additionally, apparent compensation errors are observed in models.

<p>The Southeastern United States (SE US) is one of the fastest developing regions of the nation, where summer precipitation becomes increasingly important to sustain population and economic growth. In recent decades, the variability of SE US summer precipitation has significantly intensified, leading to more frequent and severe climate extremes. However, the processes that have caused such enhanced climate variability have been poorly understood. By analyzing atmospheric hydrological cycle, diagnosing atmospheric circulation dynamics, and performing regional climate simulations, this dissertation investigates the mechanisms responsible for SE US summer precipitation variability. </p><p>Analysis of regional moisture budget indicates that the variability of SE US summer precipitation is primarily controlled by moisture transport processes associated with the variation of the North Atlantic Subtropical High (NASH) western ridge, while local water recycling is secondary. As the ridge moves northwestward (NW) into the US continent, moisture transport pathway is away from the SE US and the upward motion is depressed. Thus, rainfall decreases over the SE US, leading to dry summers. In contrast, when the ridge moves southwestward (SW), moisture convergence tends to be enhanced over the SE US, facilitating heavier rainfall and causing wetter summers. However, as the ridge is located relatively eastward, its influence on the summer precipitation is weakened. The intensified precipitation variability in recent decades is attributed to the more frequent occurrence of NW- and SW-type ridges, according to the "NASH western ridge - SE US summer precipitation" relationship. </p><p>In addition, the "NASH western ridge - SE US summer precipitation" relationship acts as a primary mechanism to determine general circulation model (GCM) and regional climate model (RCM) skill in simulating SE US summer precipitation. Generally, the state-of-the-art GCMs that are capable of representing the abovementioned relationship perform better in simulating the variability of SE US summer precipitation. Similarly, the RCM simulated summer precipitation bias over the SE US is largely caused by the errors in the NASH western ridge circulation, with the physical parameterization playing a secondary role. </p><p>Furthermore, the relationship between the NASH western ridge and SE US summer precipitation well explains the projected future precipitation changes. According to the projection by the ensemble of phase-5 of Coupled Model Intercomparison Project (CMIP5) models, summer precipitation over the SE US will become more variable in a warming climate. The enhancement of precipitation variability is due mainly to the atmospheric circulation dynamics, resulting from the pattern shift of the NASH western ridge circulation. In a warming climate, the NASH circulation tends to intensify, which forces its western ridge to extend further westward, exerting stronger impact on the SE US summertime climate. As the ridge extends westward, the NW- and SW-type ridges occur more frequently, resulting in an increased occurrence of extreme summers over the SE US. </p><p>In summary, the studies presented in this dissertation identify the NASH western ridge as a primary regulator of SE US summer precipitation at seasonal scale. The "NASH western ridge - SE US summer precipitation" relationship established in this study serves as a first order mechanism for understanding and simulating processes that influence the statistics of extreme events over the SE in the current and future climate.</p> / Dissertation

The aim of this thesis is to explore the under-studied area of deliberative democratic politics at the local level, while adding to the literature on deliberative theory itself. Empirical research was conducted through the qualitative tools of participant observation in Project Lyttelton’s Energy Matters Workshop and in-depth interviews with Project Lyttelton members, workshop participants and local government representatives. A comparative analysis was also undertaken between two locally focussed initiatives looking at citizen engagement and democracy in relation to climate change. The findings of this research suggest that Project Lyttelton’s Energy Matters Workshop answers the call for a deliberative approach through its use of the key institutional features of deliberative democratic processes. The research findings also show that local deliberative initiatives may not be about reaching consensus or agreement in relation to a particular issue such as climate change. Rather, they may be focused on building up a network of citizens that discuss new ideas, build awareness, invigorate public engagement, highlight shared interests and motivate new initiatives. However, the research data also draws attention to compelling, and as yet unanswered questions, about just what conditions are needed for local deliberation to affect public policy and climate change decision-making, how deliberative practices could be integrated within government structures themselves, how the current political framework (and context) could act as a spur to those at the local level, and how local participation and deliberation could have a voice in the largely international climate change arena. This research adds to the scholarship on deliberative theory by examining what deliberation looks like at the local level, while providing further empirical research for deliberative theory itself.

The main objective of this study was to determine the consequences of making changes to retail web-sites by examining how consumers respond to change within online retail environments. To achieve this aim, the study drew theoretical guidance from the general Stimulus-Organism-Response (SOR) paradigm. In particular, building upon web-site typology theories, the study proposed that two types of change influenced consumers’ internal responses, prompting behavioural consequences. The two types of change were Task-Relevant and Non-Task-Relevant – representing the two broad components of the retail web-site. A conceptual model was developed outlining the expected effects of change on the emotional (Arousal, Pleasure and Dominance), psychological (Flow), and cognitive (Hedonic and Utilitarian Value) states predicted to precede re-acceptance of the changed retail web-site (Attitude toward Re-patronage and Re-patronage Intention). To empirically examine this model, an online experiment (using a 2 x 2 between-subjects factorial design) was conducted, in which subjects were exposed to a modified version of a commercial personal banking web-site. A total of 292 responses were collected from Internet users in New Zealand. Simple linear regression, two- and three-stage hierarchical regression, and path analysis were used to analyse the dependence relationships outlined in the conceptual model. The results of the study suggest that both types of change have individual impacts on consumer response moreover, the effects are very different. In particular, Non-Task-Relevant Change appears to carry positive consequences, such as positive emotion, while the effects of Task-Relevant Change appear to carry negative consequences such as negative emotions and reduced value. Furthermore, findings suggest that offsetting the negative influences of change on emotion (particularly pleasure) can aid managers in minimising the negative consequences of change. The complete findings, their implications for the current research, and the provision of directions for future research are discussed in detail.

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