Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (p. 100-107).

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The first two empirical orthogonal functions of the winter (DJF) surface air temperature (SAT) over North America are associated with the North Atlantic Oscillation (NAO) and the Pacific/North American (PNA) pattern in the NCEP reanalysis. Lagged correlations between the North American SAT structures and the sea surface temperature (SST) were computed. There is a small lag between the tri-pole SST anomaly pattern of the North Atlantic Ocean and the first SAT mode. The second SAT mode lags the eastern Tropical Pacific SST anomaly by two months, associated with ENSO through the winter. A similar analysis is conducted on the seasonal forecasts to see if the forecast models capture the above links. GCM3 captures the ENSO forcing and has the PNA response. GEM captures the link between the SAT and the tripole SST anomaly pattern in North Atlantic. Although GEM captures the ENSO signal, it cannot form the PNA to further this tropical forcing into North America.

While in a typical year, approximately 1,000 tornadoes occur within the contiguous United States, the number is highly variable from 700 to almost 1200. This variability is not easily forecast on a yearly basis. ,Through the application of teleconnection patterns such as the El Nino/Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), and Pacific-North America Pattern (PNA), it is shown that relationships exist between the phase of these large-scale atmospheric circulation anomalies and tornado frequency in different regions of the United States. Correlation analysis for each phase of the different patterns show that regionality exists when considenng the pattern's correlations with tornado frequency. These patterns are reasonably explained through the use of NCEP/NCAR Reanalysis data. The most interesting result from this study is that the NAO and PNA patterns yielded similar stateby-state correlation patterns, suggesting that the two patterns may be linked as has been suggested by prior research. / Department of Geography

The purpose of this study is to examine possible relationships between changes in values of teleconnection indices related to the Southern Oscillation Index (SOI), North Atlantic Oscillation (NAO), Pacific-North American (PNA) pattern, and Arctic Oscillation (AO), and outbreaks of severe thunderstorms for specific time periods following such changes. A series of chi-squared tests are performed to determine if statistically significant relationships exist between changes in teleconnection index values and the occurrence of severe thunderstorm outbreaks. Results indicate that changes in the SOI seem to be related to an increase in the frequency of outbreaks that follow in the short-term. / Department of Geography

Graduation date: 1987

In this study the natural variability of Southern Ocean water masses on interannual to centennial time scales is investigated using a long-term integration of the Commonwealth Scientic and Industrial Research Organisation (CSIRO) coupled climate model. We focus our attention on analysing the variability of Antarctic IntermediateWater (AAIW), Circumpolar DeepWater (CDW), and Antarctic Bottom Water (AABW). We present an analysis of the dominant modes of temperature and salinity (T - S) variability within these water masses. Climate signals are detected and analysed as they get transmitted into the interior from the water mass formation regions. Eastward propagating wavenumber-1, -2, and -3 signals are identied using a complex empirical orthogonal function (CEOF) analysis along the core of the AAIW layer. Variability in air-sea heat uxes and ice meltwater rates are shown by heat and salt budget analyses to control variability of Antarctic Surface Water where density surfaces associated with AAIW outcrop. The dominant mode in the CDW layer is found to exhibit an interbasin-scale of variability originating from the North Atlantic, and propagating southward into the Southern Ocean. Salinity dipole anomalies appear to propagate around the Atlantic meridional overturning circulation with the strengthening and weakening of North Atlantic Deep Water formation. In the AABW layer, T - S anomalies are shown to originate from the southwestern Weddell Sea, driven by salinity variations and convective overturning in the region. It is also demonstrated that the model exhibits spatial patterns of T - S variability for the most part consistent with limited observational record in the Southern Hemisphere. However, some observations of decadal T - S changes are found to be beyond that seen in the model in its unperturbed state. We further assess sea surface temperature (SST) variability modes in the Indian Ocean on interannual time scales in the CSIRO model and in reanalysis data. The emergence of a meridional SST dipole during years of southwest Western Australian rainfall extremes is shown to be connected to a large-scale mode of Indian Ocean climate variability. The evolution of the dipole is controlled by variations in atmospheric circulation driving anomalous latent heat uxes with wind-driven ocean transport moderating the impact of evaporation and setting the conditions favourable for the next generation phase of an opposite dipole.

In this study the natural variability of Southern Ocean water masses on interannual to centennial time scales is investigated using a long-term integration of the Commonwealth Scientic and Industrial Research Organisation (CSIRO) coupled climate model. We focus our attention on analysing the variability of Antarctic IntermediateWater (AAIW), Circumpolar DeepWater (CDW), and Antarctic Bottom Water (AABW). We present an analysis of the dominant modes of temperature and salinity (T - S) variability within these water masses. Climate signals are detected and analysed as they get transmitted into the interior from the water mass formation regions. Eastward propagating wavenumber-1, -2, and -3 signals are identied using a complex empirical orthogonal function (CEOF) analysis along the core of the AAIW layer. Variability in air-sea heat uxes and ice meltwater rates are shown by heat and salt budget analyses to control variability of Antarctic Surface Water where density surfaces associated with AAIW outcrop. The dominant mode in the CDW layer is found to exhibit an interbasin-scale of variability originating from the North Atlantic, and propagating southward into the Southern Ocean. Salinity dipole anomalies appear to propagate around the Atlantic meridional overturning circulation with the strengthening and weakening of North Atlantic Deep Water formation. In the AABW layer, T - S anomalies are shown to originate from the southwestern Weddell Sea, driven by salinity variations and convective overturning in the region. It is also demonstrated that the model exhibits spatial patterns of T - S variability for the most part consistent with limited observational record in the Southern Hemisphere. However, some observations of decadal T - S changes are found to be beyond that seen in the model in its unperturbed state. We further assess sea surface temperature (SST) variability modes in the Indian Ocean on interannual time scales in the CSIRO model and in reanalysis data. The emergence of a meridional SST dipole during years of southwest Western Australian rainfall extremes is shown to be connected to a large-scale mode of Indian Ocean climate variability. The evolution of the dipole is controlled by variations in atmospheric circulation driving anomalous latent heat uxes with wind-driven ocean transport moderating the impact of evaporation and setting the conditions favourable for the next generation phase of an opposite dipole.

Thesis (Ph. D.)--Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2007. / "September 2007". "Joint Program in Oceanography/Applied Ocean Science and Engineering"--Cover. Title from Web page (viewed on Mar. 24, 2008). Includes bibliographical references (p. 215-225).

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (p. 145-156).