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Articles 1 - 15 of 15
Full-Text Articles in Physical Sciences and Mathematics
Seasonal Differences In The Impacts Of Ipo And Amo On Temperature And Precipitation Over South America, Thomas Favata
Seasonal Differences In The Impacts Of Ipo And Amo On Temperature And Precipitation Over South America, Thomas Favata
Legacy Theses & Dissertations (2009 - 2024)
The Atlantic Multidecadal Oscillation (AMO) and Interdecadal Pacific Oscillation (IPO) have been shown to impact temperature and precipitation across the globe. However, the seasonal differences in their impacts are not well studied. This study analyzes the seasonal differences in the impacts of the AMO and IPO on South American temperature and precipitation. Observational and reanalysis data with enough temporal coverage to isolate the multidecadal modes were used first to identify the regions impacted by the AMO and IPO through a correlation analysis. Then Empirical Orthogonal Functions (EOF) and a Maximum Covariance Analysis (MCA) were used to determine the seasonal spatial …
On The Structure And Phase Speeds Of The Kelvin Waves And Mjo Over The Indian Ocean, Ahmed Shaaban
On The Structure And Phase Speeds Of The Kelvin Waves And Mjo Over The Indian Ocean, Ahmed Shaaban
Legacy Theses & Dissertations (2009 - 2024)
Kelvin waves in the stratosphere are well known to behave as radiative gravity waves. Yet, the tropospheric component of these Kelvin waves (and other tropical modes) has often been described as superpositions between the baroclinic modes. By decomposing the Kelvin waves into upward and downward-phase components, we found that only upward-phase Kelvin waves occupy the troposphere, indicating that the tropospheric Kelvin waves are not vertical standing oscillations as previously thought. Fast Kelvin waves were found to obey the structure of radiating gravity waves, like their stratospheric counterpart, more than the moist waves. The unexpected lack of variation in vertical tilt …
Improving Our Understanding Of The Relationship Between Ocean Heat Uptake And Climate Sensitivity, Michael Cameron Rencurrel
Improving Our Understanding Of The Relationship Between Ocean Heat Uptake And Climate Sensitivity, Michael Cameron Rencurrel
Legacy Theses & Dissertations (2009 - 2024)
One of the ultimate goals of the field of climate science is to determine exactly how sensitive the Earth is to anthropogenic forcing, with far reaching implications both from a scientific and policy standpoint. However, despite decades of observational and model analysis, large uncertainties in Earth's climate sensitivity persist. Recent advances have shown that climate feedbacks, the primary mechanism driving the sensitivity spread, are dependent on the spatial patterns of the surface response, intrinsically linked to how the ocean is working to uptake and transport energy across the globe. Given the importance of reducing the range of climate sensitivity from …
Easterly Waves Over The Eastern Pacific, Victor Manuel Torres Puente
Easterly Waves Over The Eastern Pacific, Victor Manuel Torres Puente
Legacy Theses & Dissertations (2009 - 2024)
The research in this thesis explores different processes associated with the life cycle of Easterly Waves over the tropical Eastern Pacific. These include genesis, structural evolution, intensification and a dissipating stage.
Dynamical Downscaling Of Near-Term Climate Variability And Change For The Main Hawaiian Islands Using Wrf, Katrina Marie Fandrich
Dynamical Downscaling Of Near-Term Climate Variability And Change For The Main Hawaiian Islands Using Wrf, Katrina Marie Fandrich
Legacy Theses & Dissertations (2009 - 2024)
As climate models continue to improve, the demand from resource managers and decision-makers for more accurate climate projections is increasing. However, natural climate variability poses a limit to the confidence in regional climate change projections, particularly for the mid-21st century. The unique geographic location of the Hawaiian Islands and its regional climate provide a challenging opportunity for climate modelers. The goal of this project is to examine both the Pacific Decadal Oscillation (PDO) and anthropogenic climate change for their impacts on near-term rainfall and temperature projections for the Hawaiian Islands. Of primary interest are the questions 1) is there a …
Extratropical Precursors To The Onset Of Madden-Julian Oscillation Deep Convection Over The Western Indian Ocean, Jennifer Anne Gahtan
Extratropical Precursors To The Onset Of Madden-Julian Oscillation Deep Convection Over The Western Indian Ocean, Jennifer Anne Gahtan
Legacy Theses & Dissertations (2009 - 2024)
Madden-Julian Oscillation (MJO) deep convection often initially forms over the western Indian Ocean and is frequently preceded by upper tropospheric circulation precursors. These precursors include subtropical cyclonic Rossby gyres near eastern Africa and Southwest Asia, coherent extratropically circumnavigating Rossby wave trains extending back across the Atlantic, and tropically circumnavigating easterlies. Easterly acceleration associated with the circulation precursors may help to reduce large-scale subsidence over the tropical Indian Ocean prior to convective onset; when intraseasonal easterly acceleration reaches the western extent of a region of intraseasonal upper level westerlies, it produces upper-tropospheric divergence, providing a forcing for upward motion.
Predictability Of African Easterly Waves In An Operational Ensemble Prediction System, Travis J. Elless
Predictability Of African Easterly Waves In An Operational Ensemble Prediction System, Travis J. Elless
Legacy Theses & Dissertations (2009 - 2024)
African easterly waves (AEWs) are the primary synoptic-scale weather feature found in sub-Saharan Africa during boreal summer. Many studies have used observations and idealized models to highlight processes associated with the movement and growth of AEWs, yet there have been few studies documenting the performance of operational ensemble prediction systems (EPSs) for these phenomena. Here, the predictability of AEWs in ECMWF EPS forecasts is assessed during two periods of enhanced AEW activity (July--September 2007--2009 and 2011--2013). Specifically, AEW predictability is analyzed through three main areas of focus: 1) verifying AEW position and intensity forecasts, and assessing their relation to convective …
Climate Fingerprints Of The Interdecadal Pacific Oscillation, Bo Dong
Climate Fingerprints Of The Interdecadal Pacific Oscillation, Bo Dong
Legacy Theses & Dissertations (2009 - 2024)
The Interdecadal Pacific Oscillation (IPO) is a multi-decadal quasi-oscillation seen primarily in tropical and extratropical Pacific sea surface temperatures (SSTs). Interacting with the atmosphere, the IPO has been shown to affect global and regional climate. However, a quantitative global synthesis of the IPO’s climate fingerprints and the underlying mechanisms are still lacking. Based on observational and reanalysis data and atmospheric model simulations, this dissertation investigates the IPO’s influence on regional climates over the globe, and its interactions with El Niño-Southern Oscillation (ENSO) and global warming.
Understanding Predictive Skill Of Arctic Sea Ice And Its Linkage With Mid-Latitude Weather And Climate In The Ncep Climate Forecast System, Colleen Mchugh
Understanding Predictive Skill Of Arctic Sea Ice And Its Linkage With Mid-Latitude Weather And Climate In The Ncep Climate Forecast System, Colleen Mchugh
Legacy Theses & Dissertations (2009 - 2024)
Arctic climate is undergoing significant change, particularly rapid decline of sea ice. Arctic sea ice plays an important role in local, regional, and global climate through a variety of physical processes as seen in observational analysis as well as modeling studies. Recent research suggested that decreasing autumn and winter Arctic sea ice extent (SIE) has been shown to have an effect on mid-latitude weather patterns during the winter months. Therefore, accurate forecasts of Arctic sea ice extent and the associated teleconnections with the mid-latitudes are important for accurate seasonal climate prediction. The NCEP Climate Forecast System version 2 (CFSv2) is …
Understanding Climatic Adjustments To Variations In Tropical Ocean Heat Transport, Michael Cameron Rencurrel
Understanding Climatic Adjustments To Variations In Tropical Ocean Heat Transport, Michael Cameron Rencurrel
Legacy Theses & Dissertations (2009 - 2024)
One of the outstanding problems within the climate community has been how to reconcile the geological proxy records of past warm, equable climates, characterized by both an increase in the global mean surface temperature and a decrease in the equator-to-pole temperature gradient, with numerical simulations of the same period. Recent work has shown that tectonic driven changes in the meridional ocean heat transport (OHT) may have played a signicant role in the warming. Here, we study the adjustment of the climate to variations in OHT using a suite of slab-ocean aquaplanet GCM simulations spanning 24 different imposed variations in OHT …
Understanding The Dependence Of Radiative Feedbacks And Clouds On The Spatial Structure Of Ocean Heat Uptake, Lance Rayborn
Understanding The Dependence Of Radiative Feedbacks And Clouds On The Spatial Structure Of Ocean Heat Uptake, Lance Rayborn
Legacy Theses & Dissertations (2009 - 2024)
Ocean heat uptake and radiative forcing are important for understanding transient climate change. Differences in efficacy of ocean heat uptake (suppression of surface warming per unit energy flux into the deep oceans relative to CO2 forcing) account for a substantial fraction of the spread in transient warming between models. Rose et al. (2014) studied the dependence of efficacy on the spatial pattern of ocean heat uptake in an ensemble of aquaplanet simulations with prescribed ocean heat uptake, and found large differences in model responses to high versus low latitude uptake. This study accurately quantifies these model responses through the use …
Air-Sea Carbon Dioxide Exchange In The Southern Ocean And Antarctic Sea Ice Zone, Brian Butterworth
Air-Sea Carbon Dioxide Exchange In The Southern Ocean And Antarctic Sea Ice Zone, Brian Butterworth
Legacy Theses & Dissertations (2009 - 2024)
The Southern Ocean is an important part of the global carbon cycle, responsible for roughly half of the carbon dioxide (CO2) absorbed by the global ocean. The air-sea CO2 flux (Fc) can be expressed as the product of the water-air CO2 partial pressure difference (ΔpCO2) and the gas transfer velocity (k), an exchange coefficient which represents the efficiency of gas exchange. Generally, Fc is negative (a sink) throughout the Southern Ocean and Antarctic sea ice zone (SIZ), but uncertainty in k has made it difficult to develop an accurate regional carbon budget. Constraining the functional dependence of k on wind …
Modulation Of East African Precipitation By The Indian Ocean Dipole (Iod) And Enso, Ahmed Shaaban
Modulation Of East African Precipitation By The Indian Ocean Dipole (Iod) And Enso, Ahmed Shaaban
Legacy Theses & Dissertations (2009 - 2024)
Tropical East Africa is influenced by two main rainy seasons, during autumn and spring. During autumn, tropical East African precipitation is clearly influenced by Indian Ocean Dipole (IOD) and/or ENSO. During spring, there is no clear SST pattern in the Indian Ocean. The association between El Niño and positive IOD phases is much stronger than the association between La Niña and negative IOD during October and November. During October, the association between El Niño and wet condition over tropical eastern Africa is stronger than association between La Niña and dry conditions. During November, the association between positive IOD and eastern …
On The Mjo And Anticyclonic Wavebreaking, Kyle Macritchie
On The Mjo And Anticyclonic Wavebreaking, Kyle Macritchie
Legacy Theses & Dissertations (2009 - 2024)
The Madden Julian oscillation (MJO) is the primary mode of intraseasonal variability in the tropics. The MJO often couples with convection as it moves over the Indian Ocean and decouples as it leaves the west Pacific Ocean. The association between convection coupled to the MJO and the midlatitude flow pattern has been the primary focus of numerous studies. In particular, it has been shown that there is a statistical relationship between the position and strength of the MJO and anticyclonic wavebreaking (AWB). This study expands on this statistical relationship by examining, in detail, the two-way relationship between the MJO and …
An Analysis Of The Formation And Evolution Of The 1989 Western North Pacific Subtropical Gyre, Brian Andrew Crandall
An Analysis Of The Formation And Evolution Of The 1989 Western North Pacific Subtropical Gyre, Brian Andrew Crandall
Legacy Theses & Dissertations (2009 - 2024)
This thesis conducts an observational study of a large cyclonic gyre that developed in the Western North Pacific (WNP) in late July 1989. For a period of six days, azimuthally-averaged winds at 850 hPa remained cyclonic out from the center of circulation to the 2000 km radius, with azimuthally-averaged tangential wind speeds at or greater than 10 m s-1. The gyre exhibited an asymmetric convection pattern, with the center, north and west flanks devoid of large convective areas, but the southern and eastern flanks maintained large-scale convective regions, extending as much as 4000 km in longitude.