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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
191

Numerical studies of mesoscale eddies using quasigeostrophic and primitive equation ocean models

Batteen, Mary L. 30 April 1984 (has links)
The dynamical role of mesoscale eddies in the ocean general circulation is investigated using eddy-resolving quasigeostrophic (QG) and primitive equation (FE) models which are parametrically identical. The results of both QG and FE numerical experiments in mid-latitude, rectangular ocean basins are systematically intercompared and extensively analyzed in terms of basic quantities: energetics, relative and potential vorticity, and eddy momentum and heat transports. Although overall the analyses show that the results are fairly similar between the two models, a closer examination reveals some significant differences. Most of these differences are due to the presence of Kelvin waves along the lateral boundaries of the PE model. These waves are the main source for mean and eddy divergent kinetic energy. Further model parameter studies are needed to determine whether the presence of these Kelvin waves is due to numerics, physics, or a combination of the two, and if the two-day sampling rate commonly used for obtaining eddy statistics significantly aliases these high frequency waves. / Graduation date: 1984
192

The study of cirrus clouds using airborne and satellite data

Meyer, Kerry Glynne 30 September 2004 (has links)
Cirrus clouds are known to play a key role in the earth's radiation budget, yet are one of the most uncertain components of the earth-atmosphere system. With the development of instruments such as the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and the Moderate-resolution Infrared Spectroradiometer (MODIS), scientists now have an unprecedented ability to study cirrus clouds. To aid in the understanding of such clouds, a significant study of cirrus radiative properties has been undertaken. This research is composed of three parts: 1) the retrieval of tropical cirrus optical thickness using MODIS level-1b calibrated radiance data, 2) a survey of tropical cirrus cloud cover, including seasonal variations, using MODIS level-3 global daily gridded data, and 3) the simultaneous retrieval of cirrus optical thickness and ice crystal effective diameter using AVIRIS reflectance measurements.
193

Stratospheric aerosol retrieval from OSIRIS limb scattered sunlight spectra

Bourassa, Adam Edward 30 April 2007
The recent development of satellite observations of limb scattered sunlight at optical wavelengths has afforded a new opportunity to measure the vertical structure of atmospheric composition from the upper troposphere to the mesosphere, on a global scale. The determination of profiles of atmospheric composition from observed limb radiance profiles requires two elements, a forward radiative transfer model and a species specific inversion algorithm. In this work, the development of a new, fully spherical, successive orders radiative transfer model, SASKTRAN, for the analysis of limb scattered sunlight is presented. The model is incorporated into a novel relaxation algorithm that employs spectral ratios to retrieve profiles of stratospheric aerosols from limb radiance measurements collected by the Canadian OSIRIS instrument on the Odin satellite.<p>The SASKTRAN forward model results compare favorably with both OSIRIS observations as well as with other radiative transfer model calculations while remaining computationally practical for the operational inversion of large satellite data sets.<p>The spectral ratio relaxation algorithm is able to retrieve aerosol number density profiles at stratospheric altitudes from limb radiance profiles assuming the height profile of the aerosol particle size distribution is known. The equivalent aerosol extinction derived from the OSIRIS measurements at visible wavelengths agrees with coincident occultation measurements from other satellite instrumentation to within 15% when a size distribution appropriate for background aerosol conditions is used. Finally, it is demonstrated that the incorporation of simultaneous infra-red observations at 1530 nm into the inversion yields a useful proxy for the aerosol size distribution parameters.
194

Stratospheric aerosol retrieval from OSIRIS limb scattered sunlight spectra

Bourassa, Adam Edward 30 April 2007 (has links)
The recent development of satellite observations of limb scattered sunlight at optical wavelengths has afforded a new opportunity to measure the vertical structure of atmospheric composition from the upper troposphere to the mesosphere, on a global scale. The determination of profiles of atmospheric composition from observed limb radiance profiles requires two elements, a forward radiative transfer model and a species specific inversion algorithm. In this work, the development of a new, fully spherical, successive orders radiative transfer model, SASKTRAN, for the analysis of limb scattered sunlight is presented. The model is incorporated into a novel relaxation algorithm that employs spectral ratios to retrieve profiles of stratospheric aerosols from limb radiance measurements collected by the Canadian OSIRIS instrument on the Odin satellite.<p>The SASKTRAN forward model results compare favorably with both OSIRIS observations as well as with other radiative transfer model calculations while remaining computationally practical for the operational inversion of large satellite data sets.<p>The spectral ratio relaxation algorithm is able to retrieve aerosol number density profiles at stratospheric altitudes from limb radiance profiles assuming the height profile of the aerosol particle size distribution is known. The equivalent aerosol extinction derived from the OSIRIS measurements at visible wavelengths agrees with coincident occultation measurements from other satellite instrumentation to within 15% when a size distribution appropriate for background aerosol conditions is used. Finally, it is demonstrated that the incorporation of simultaneous infra-red observations at 1530 nm into the inversion yields a useful proxy for the aerosol size distribution parameters.
195

Concentrations and distribution of persistent organic pollutants in the atmosphere of southern Taiwan

Huang, Xiu-Ying 23 July 2012 (has links)
Persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs) and polybrominated diphenylethers (PBDEs), are widely distributed in the environment. Several studies have demonstrated that these pollutants will cause potential impacts such as carcinogenic and mutagenic for human health. In this study, four different types of sampling stations were chosen. Two of the sampling sites are located in Kaohsiung city, which is an industrialized city with densely population in southern Taiwan (KHU and KHC). The other sampling sites are in a rural coastal area (KT) and an offshore island (LY), respectively. We determined the concentrations of PCBs and PBDEs in the atmosphere to identify the spatial and temporal distributions of PCBs and PBDEs in southern Taiwan. Hierarchical cluster analysis (HCA) and principal components analysis (PCA) of congener-specific composition of PCBs and PBDEs were performed with the commercial products to investigate the relationship of regional signatures and possible pollution sources. Finally, back trajectory analysis was undertaken to gain a better understanding of long-distance transport contribution to the studied area. The concentrations of £UPCBs in the ambient air ranged from 9.51 to 482 pg m-3, with an average concentration of 162¡Ó155 pg m-3. The mean PCB concentrations in gas and particle phase were 159¡Ó153 pg m-3 and 3.04¡Ó2.38 pg m-3, respectively. The concentrations of £UPBDEs in the ambient air ranged from 3.42 to 166 pg m-3, with an average concentration of 31.7¡Ó37.3 pg m-3. The average PBDE concentrations in gas and particle phase were 7.22¡Ó6.50 pg m-3 and 23.7¡Ó33.4 pg m-3, respectively. Comparison of the total PCB and PBDE concentrations from the four sampling sites showed that the total PCB and PBDE concentrations at the Kaohsiung urban site (KHU) and Kaohsiung coastal site (KHC) were higher than those at a rural coastal site (Kenting, KT) and an offshore island site (Lanyu, LY), suggesting that densely population and heavy industrial park may be the major contributor of PCBs and PBDEs . Results from HCA, PCA and compositional patterns of PCBs indicate that offshore island site (Lanyu, LY) was different from KHU, KHC and KT. Lower chlorinated congeners (dichlorobiphenyls to hexachlorobiphenyls) were predominant in the gas phase. Since most of the lower molecular weight congeners were below the detection limit, the total PCB concentrations were found at much lower level in LY sampling sites. In addition, a significantly higher proportion of high-chlorinated congeners, was observed at LY, suggesting that there may be local pollution sources in this area. Results from HCA, PCA and compositional patterns of PBDEs indicate that the samples from February and October were dominated by BDE-209, while the samples from July were dominated by BDE-71, BDE-47 and BDE-99, suggesting that this might be due to the significantly low concentrations of suspended particles (PM10) in July. Since much higher temperature was observed in July, these lower brominated congeners may be released much easier from the sediment, water, and brominated-containing products due to smaller molecular size and higher vapor pressure. Moreover, debromination of the deca-BDEs had been observed in the environment. Several studies have shown that photolytic debromination of BDE-209 is possible pathway for the formation of lower brominated-BDEs. TEQ was used to determine the level of pollution for environment and human health. In this study area, the TEQ ranged from 0.145 to 0.878 pg-TEQ m-3, with an average TEQ of 0.0004¡Ó0.0003 pg-TEQ m-3 in gas-phase of ambient air. PCB114 was observed to be the predominant congener in this study.
196

Convective momentum transport over the tropical Pacific /

Carr, Matthew Tobias. January 2001 (has links)
Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 114-120).
197

Wave-mean-flow interaction and the annular mode /

Lorenz, David Joseph. January 2003 (has links)
Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (p. 77-80).
198

Moisture and diabatic initialization based on radar and satellite observations /

Zhang, Jian, January 1999 (has links)
Thesis (Ph. D.)--University of Oklahoma, 1999. / Includes bibliographical references (leaves 184-194).
199

Recent interdecadal variations in the tropical atmosphere : evidence and idealized GCM simulations /

Gong, Xiaofeng, January 1998 (has links)
Thesis (Ph. D.)--University of Oklahoma, 1998. / Includes bibliographical references (leaves 215-221).
200

The peculiar behavior of baroclinic waves during the midwinter suppression of the Pacific storm track /

Yin, Jeffrey Hiapo. January 2002 (has links)
Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 115-118).

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