As a global climate phenomenon, the El Ni??o-Southern Oscillation (ENSO) involves the coupling of the ocean and the atmosphere. Most climate prediction studies have, by far, only investigated the teleconnections between global climatic anomalies and the ???surface??? predictors of ENSO. The prediction models resulting from these studies have generally suffered from inadequate, if not the lack of, skill across the so-called boreal ???spring barrier???. This is illustrated in the first part of this thesis where the applicability of the SOI phase for long-lead rainfall projections in Australia is discussed. With the increasing availability of subsurface ocean temperature data, the characteristics of the Pacific Ocean???s heat content and its role in ENSO are now better understood. The second part of this thesis investigated the predictability of ENSO using the thermocline as a predictor. While the persistence and SST-based ENSO hindcasts dropped in skill across the spring barrier, the thermocline-based hindcasts remained skillful even up to a lag of eighteen months. Continuing on the favorable results of ENSO prediction, the third part of this thesis extended the use of the thermocline in the prediction of Australia???s rainfall and streamflow. When compared to models that use ???surface??? predictors, the model that incorporated thermocline information resulted in more skillful projections of rainfall and streamflow especially at long lead-times. More importantly, significant increases in skill of autumn and winter projections demonstrate the ability of the subsurface ocean to retain some climatic memory across the predictability barrier. This resilience can be attributed to the high persistence of the ocean heat content during the first half of the year. Based on weighting, the model averaging exercise also affirmed the superiority of the ???subsurface??? model over the ???surface??? models in terms of streamflow projections. The encouraging findings of this study could have far-reaching implications not only to the science of ENSO prediction but also to the more pragmatic realm of hydrologic forecasting. What this study has demonstrated is an alternative predictor that is suitable for the long range forecasting of ENSO, rainfall and streamflow. With better hydrologic forecasting comes significant improvement in the management of reservoirs which eventually leads to an increase in the reliability and sufficiency of water supply provision.

Abstract not available

Recent changes in climate have increased public attention and scientific evaluation of climate impacts on wild animals and plants. Variation in local weather and regional climate may affect breeding success in birds. Migratory species may be sensitive to these changes as breeding and wintering areas may experience different climate variations; some insectivorous species may be unable to alter timing of migration or laying dates and experience a mismatch between timing of nesting and peak insect availability for their nestlings. Therefore, I investigated the influence of local weather variables and regional climate on breeding performance of an insectivorous migrant songbird, the Tree Swallow (<i>Tachycineta bicolor</i>), and tried to examine effects of a mismatch between the timing of breeding and food availability.<p>I used a 14 year data set from St. Denis, Saskatchewan, Canada, 1991-2004, to evaluate correlations among local weather, wetland conditions, aerial insects and regional climate indices and their relationships with variation in clutch initiation date, clutch size, and fledging success. Swallows returned to the study site in late April each year. Annual variation in median clutch initiation date was best explained by mean minimum temperatures during 1-15 May. Larger clutches were laid in years with higher pond water levels (possibly an indication of increased insect availability) and when the Southern Oscillation Index (SOI) was positive (representing La Niña conditions). Fledging success was not influenced greatly by any explanatory variable; however, fledging success tended to increase in years with higher average temperatures. Individual variation in clutch initiation date was examined using path analysis. I found high correlations between initiation date and both local environmental variables and regional climate indices; earlier nesting was associated with warmer temperatures (increased local temperatures, more positive North Atlantic Oscillation Index (NAOI) values and more negative SOI values) and decreased moisture (more positive NAOI values). Two reduced data sets, including female age or insect abundance, were also examined. Clutches were initiated earlier by older females and during springs with higher abundance of aerial insects.<p>I applied two heating treatments to nest boxes used by pre-laying swallows and compared reproductive measures (timing of nesting, laying sequence, clutch size, egg weight and fledging success) of birds using heated boxes to those of females attending unheated control boxes. However, I was unable to directly examine the predictions of the mismatch hypothesis because nest box heating failed to advance laying dates. Furthermore, no increases in clutch size, egg weight and fledging success were detected between treatment and control nests. Although box heating increased nest temperatures an average of 6.1C (+ 0.8 SE) over controls, length of time females spent in heated boxes may have been too short to alleviate energetic constraints on egg production, or energy savings associated with box use were insufficient to supersede the influence of ambient environmental conditions that control food availability and energy expenditure of foraging swallows. My results demonstrated that local and regional climate variation strongly affected timing of nesting in swallows, likely via their effects on food supply.

Teleconnections between ENSO events and growing-season precipitation variations on the Canadian Prairies are examined. Correlation and composite analyses indicate that between 1948 and 1991, El Nino events were associated with more frequent extended dry spells. Conversely, La Nina events coincided with fewer extended dry spells. Both relationships occurred during the third growing season following the onset of the ENSO events (i.e. approximately a 10-season or 30-month lag). A series of atmosphere - ocean teleconnections over the Pacific Ocean including Pacific North America (PNA) circulation patterns, North Pacific sea-surface temperature anomalies and upper-atmospheric circulation anomalies were found to result in growing-season precipitation variations over the Canadian Prairies. Results of this analysis are incorporated into a conceptual model which may form the basis of a long-range forecasting technique of growing-season precipitation variations on the Canadian Prairies.

Recent changes in climate have increased public attention and scientific evaluation of climate impacts on wild animals and plants. Variation in local weather and regional climate may affect breeding success in birds. Migratory species may be sensitive to these changes as breeding and wintering areas may experience different climate variations; some insectivorous species may be unable to alter timing of migration or laying dates and experience a mismatch between timing of nesting and peak insect availability for their nestlings. Therefore, I investigated the influence of local weather variables and regional climate on breeding performance of an insectivorous migrant songbird, the Tree Swallow (<i>Tachycineta bicolor</i>), and tried to examine effects of a mismatch between the timing of breeding and food availability.<p>I used a 14 year data set from St. Denis, Saskatchewan, Canada, 1991-2004, to evaluate correlations among local weather, wetland conditions, aerial insects and regional climate indices and their relationships with variation in clutch initiation date, clutch size, and fledging success. Swallows returned to the study site in late April each year. Annual variation in median clutch initiation date was best explained by mean minimum temperatures during 1-15 May. Larger clutches were laid in years with higher pond water levels (possibly an indication of increased insect availability) and when the Southern Oscillation Index (SOI) was positive (representing La Niña conditions). Fledging success was not influenced greatly by any explanatory variable; however, fledging success tended to increase in years with higher average temperatures. Individual variation in clutch initiation date was examined using path analysis. I found high correlations between initiation date and both local environmental variables and regional climate indices; earlier nesting was associated with warmer temperatures (increased local temperatures, more positive North Atlantic Oscillation Index (NAOI) values and more negative SOI values) and decreased moisture (more positive NAOI values). Two reduced data sets, including female age or insect abundance, were also examined. Clutches were initiated earlier by older females and during springs with higher abundance of aerial insects.<p>I applied two heating treatments to nest boxes used by pre-laying swallows and compared reproductive measures (timing of nesting, laying sequence, clutch size, egg weight and fledging success) of birds using heated boxes to those of females attending unheated control boxes. However, I was unable to directly examine the predictions of the mismatch hypothesis because nest box heating failed to advance laying dates. Furthermore, no increases in clutch size, egg weight and fledging success were detected between treatment and control nests. Although box heating increased nest temperatures an average of 6.1C (+ 0.8 SE) over controls, length of time females spent in heated boxes may have been too short to alleviate energetic constraints on egg production, or energy savings associated with box use were insufficient to supersede the influence of ambient environmental conditions that control food availability and energy expenditure of foraging swallows. My results demonstrated that local and regional climate variation strongly affected timing of nesting in swallows, likely via their effects on food supply.

A simple correlation analysis was used to investigate the linear relationships between sea surface temperature (SST) and monthly flow of Ganges and Brahmaputra at the borders of Bangladesh and India using approximately 50 years of river discharge data. Strong correlations were found between the equatorial Pacific SST and boreal summer Ganges discharge from three-month lag to two-month lead times. The El Nio-Southern Oscillation (ENSO) explains Ganges flow variance exceeding 0.95 significance level using both the Nino 3.4 SST correlation and the composites made for El Nio (La Nina) periods. The May SST of the southwest Pacific Ocean to the east of Australia continent has a strong correlation (>0.6) with early summer Ganges discharges. Using a lag correlation analysis of Ganges discharge and SST, we found a steady and continuous development in the Nino 3.4 SST relationship, and a strong correlation with the southwest Pacific SST which is most pronounced three-four months prior to the onset of Asian summer monsoon. These relationships mean that at least 25% of the interannual summer Ganges River discharge variability can be explained by antecedent equatorial and southwest Pacific SST. It provides a possible statistical method for linear forecasting two or three months in advance. The Brahmaputra River discharge, on the other hand, shows weak relationships with tropical SST variability except for the Bay of Bengal and the higher northern latitudes of the Pacific.

Thesis (Ph.D.)--University of Delaware, 2009. / Principal faculty advisor: Daniel J. Leathers, Dept. of Geography. Includes bibliographical references.

The El Niño-Southern Oscillation (ENSO) dominates global interannual climate variability. However, the imprint of anthropogenic climate change hinders understanding of natural ENSO variability. Model predictions of the response of future ENSO variability to anthropogenic forcing are highly uncertain. A better understanding of how ENSO operates during different mean climate states may improve predictions of its future behavior. This study develops a technique to quantify the response of tropical Pacific sea surface temperature and salinity to ENSO variations. This analysis defines expected regional relationships between ENSO forcing and the tropical Pacific climate response. For example, the western tropical Pacific records El Niño events with greater skill than La Niña events; whereas the oceans near the South Pacific Convergence Zone (SPCZ) preferentially record La Niña events. This baseline understanding of regional skill calibrates interpretations of both modern and pre-instrumental coral geochemical climate proxy records. A suite of monthly resolved 18O variations in a fossil corals (Porites spp.) from the tropical western Pacific (Papua New Guinea) and the SPCZ (Vanuatu) are used to develop case studies of ENSO variability under external forcing conditions that differ from the modern climate. A record from Misima, Papua New Guinea (1411-1644 CE) spans a period of reduced solar forcing that coincides with the initiation of the Little Ice Age. This record indicates that the surface ocean in this region experienced a small change in hydrologic balance with no change in temperature, extended periods of quiescence in El Niño activity, reduced mean El Niño event amplitudes, and fewer large amplitude El Niño events relative to signals captured in regional modern records. Several multidecadal (~30-50 year) coral records from Tasmaloum, Vanuatu during the Medieval Climate Anomaly (~900-1300 CE), a period of increased solar forcing, depict ENSO variability that is generally lower than modern times. However, these records often cannot be distinguished from 20th century ENSO variability due to ENSO variability uncertainty associated with record lengths. Neither record can be tied to concurrent changes in solar or volcanic forcing, calling into question the paradigm of ENSO variability being predominantly mediated by external forcing changes on multidecadal time scales. / text

Previous correlations have been established between the El Nino Southern Oscillation (ENSO) and both the tropical north Atlantic sea-surface temperatures (SSTs) and precipitation anomalies in the southeastern and mid-Atlantic states. Both bivariate and partial correlations are used over a five and six-month lag to assess the relevance the tropical Atlantic SSTs have in eastern United States precipitation patterns. Significant correlations between Pacific SSTs and precipitation were found during winter months which agree with previous literature. The relationship with the Atlantic SSTs was less robust, as some significant values were established over three seasons, excluding winter. Only the spring season showed a partial explanation of the Atlantic SST's role in the precipitation's response to Pacific SSTs. These relationships did not occur during the times when significant correlations were made between Pacific SSTs and precipitation. / Department of Geography

Mode of access: World Wide Web. / Thesis (Ph. D.)--University of Hawaii at Manoa, 2004. / Includes bibliographical references (leaves 162-175). / Electronic reproduction. / Also available by subscription via World Wide Web / xx, 175 leaves, bound ill. (some col.), maps (some col.) 29 cm