Dissertations / Theses on the topic 'Atmospheric transport of freshwater'
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Tonin, Hemerson E., and hemer tonin@flinders edu au. "Atmospheric freshwater sources for eastern Pacific surface salinity." Flinders University. Chemistry, Physics and Earth Sciences, 2006. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20061031.080144.
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The remarkable salinity difference between the upper Pacific and Atlantic Oceans is often explained through net export of water vapour across Central America. To investigate this mechanism a study of salinity signals in the Equatorial Pacific Ocean current system was made looking at responses to fresh water input from two sources (local versus remote - Atlantic Ocean) as well as a combination of the two. Statistical analyses (Empirical Orthogonal Functions, Single Value Decomposition and Wavelet analysis) were used to split the main sources of the atmospheric freshwater input into local and remote contributions and to quantify both contributions. The remote source was assumed to have been transported over Central America from the Atlantic Ocean as an atmospheric freshwater flux, whereas the local source originated in the Pacific Ocean itself. The analysis suggests that 74% of the total variance in precipitation over the tropical eastern Pacific is due to water vapour transport from the Atlantic. It also demonstrates strong influence of ENSO events, with maximum correlation at a two months time lag. During La Ni�a periods the precipitation variance is more closely related to water vapour transport across Central America (the remote source), while during El Ni�o periods it is more closely related to the water vapour transport by Southerly winds along the west coast of South America (the local source). The current and temperature fields provided by the Modular Ocean Model (version 2) were used to study the changes in the salinity field when freshwater was added to or removed from the model. ECMWF ERA-40 data taken from the ECMWF data server was used to determine the atmospheric flux of freshwater at the ocean surface, in the form of evaporation minus precipitation (E-P). The Mixed Layer Depth (MLD) computed from temperature and salinity fields determines to what depth the salinity's dilution/concentration takes place for every grid point. Each MLD was calculated from the results of the previous time step, and the water column was considered well mixed from the surface to this depth. The statistical relationships were used to reconstruct the precipitation over the tropical eastern Pacific. A numerical ocean model, which uses currents and temperature from a global ocean model and is forced by precipitation, was used to study the ocean's response to either the remote or the local source acting in isolation. Through time lag correlation analysis of the sea surface salinity anomalies produced by the variation in the reconstructed precipitation fields, it is found that the anomaly signals of salinity propagate westward along the Equator at a rate of approximately 0.25 m.s-1 (6.1 degrees per month).
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Fong, Derek Allen. "Dynamics of freshwater plumes: observations and numerical modeling of the wind-forced response and alongshore freshwater transport." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/58510.
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Thesis (Ph. D.)--Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 1988.Includes bibliographical references (leaves 163-172).
A freshwater plume often forms when a river or an estuary discharges water onto the continental shelf. Freshwater plumes are ubiquitous features of the coastal ocean and usually leave a striking signature in the coastal hydrography. The present study combines both hydrographic data and idealized numerical simulations to examine how ambient currents and winds influence the transport and mixing of plume waters. The first portion of the thesis considers the alongshore transport of freshwater using idealized numerical simulations. In the absence of any ambient current, the downstream coastal current only carries a fraction of the discharged fresh water; the remaining fraction recirculates in a continually growing "bulge" of fresh water in the vicinity of the river mouth. The fraction of fresh water transported in the coastal current is dependent on the source conditions at the river mouth. The presence of an ambient current augments the transport in the plume so that its freshwater transport matches the freshwater source. For any ambient current in the same direction as the geostrophic coastal current, the plume will evolve to a steady-state width. A key result is that an external forcing agent is required in order for the entire freshwater volume discharged by a river to be transported as a coastal current. The next section of the thesis addresses the wind-induced advection of a river plume, using hydrographic data collected in the western Gulf of Maine. The observations suggest that the plume's cross-shore structure varies markedly as a function of fluctuations in alongshore wind forcing. Consistent with Ekman dynamics, upwelling favorable winds spread the plume offshore, at times widening it to over 50 km in offshore extent, while downwelling favorable winds narrow the plume width to a few Rossby radii. Near-surface current meters show significant correlations between cross-shore currents and alongshore wind stress, consistent with Ekman theory. Estimates of the terms in the alongshore momentum equation calculated from moored current meter arrays also indicate an approximate Ekman balance within the plume. A significant correlation between alongshore currents and alongshore wind stress suggests that interfacial drag may be important. The final section of the thesis is an investigation of the advection and mixing of a surface-trapped river plume in the presence of an upwelling favorable wind stress, using a three-dimensional model in a simple, rectangular domain. Model simulations demonstrate that the plume thins and is advected offshore by the cross shore Ekman transport. The thinned plume is susceptible to significant mixing due to the vertically sheared horizontal currents. The first order plume response is explained by Ekman dynamics and a Richardson number mixing criterion.
by Derek Allen Fong.
Ph.D.
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Dodd, Paul A. "Freshwater transport in the East Greenland current." Thesis, University of East Anglia, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.446524.
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Shuckburgh, Emily Fleur. "Mixing and transport in atmospheric flows." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621641.
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Delwiche, Kyle Brook. "Chemical transport by methane ebullition in a freshwater lake." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119326.
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Thesis: Ph. D. in Environmental Engineering, Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2018.Cataloged from PDF version of thesis.
Includes bibliographical references.
Methane bubbling from lakes contributes significantly to atmospheric methane levels, and methane is second only to carbon dioxide in global warming potential. Microorganisms in aquatic sediments produce methane while consuming organic matter, and the majority of this methane is released via bubbling. Bubbles dissolve as they rise, and the fraction of original methane that dissolves versus escapes to the atmosphere is strongly influenced by bubble size. While bubble sizes are critical to methane fate, traditional methods of measuring bubbles sizes in situ are resource intensive (i.e. sonar or video cameras). In this work we design, build, and deploy a fleet of novel optical bubble size sensors capable of measuring methane bubbles in situ for long periods of time. Data from our field campaign on Upper Mystic Lake, MA illuminate spatial differences in bubble size distributions and provide an estimate of the contribution from methane bubble dissolution to dissolved methane accumulation. These results improve our understanding of processes governing the emission of this important greenhouse gas. In addition to transporting gas, bubbles effectively transport particles in water columns. This process has been used extensively in industry since the 1900s to separate chemicals of interest from bulk solutions. While bubbles also transport particulate matter in marine systems, to date very little work has focused on the possibility that methane bubbles transport particles in freshwater systems. We use laboratory and field experiments on Upper Mystic Lake to show that bubbles can transport arsenic-containing sediment particles to the surface of the lake from depths exceeding 15 m. While we estimate that arsenic transport is insignificant at the relatively modest methane bubbling levels in Upper Mystic Lake, other water bodies experience an order of magnitude more ebullition and bubbling may therefore constitute a significant contaminant flux in these systems. Furthermore, bubbles may also transport organisms (or pathogens) from the sediment to the water surface.
by Kyle Brook Delwiche.
Ph. D. in Environmental Engineering
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Macdonald, Alison Marguerite. "Oceanic fluxes of mass, heat, and freshwater : a global estimate and perspective." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11079.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1995.Includes bibliographical references (leaves 316-326).
by Alison Marguerite Macdonald.
Ph.D.
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Rudge, Stephen Alan. "The biological transport of radionuclides in grassland and freshwater ecosystems." Thesis, University of Liverpool, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292164.
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Lanser, Debby. "Numerical methods for atmospheric flow and transport problems." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2002. http://dare.uva.nl/document/64490.
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Raff, Jonathan Daniel. "Transport of organic pollutants and their atmospheric fates." [Bloomington, Ind.] : Indiana University, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3292440.
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Thesis (Ph. D.)--Indiana University, School of Public and Environmental Affairs, 2007.Title from dissertation home page (viewed May 28, 2008). Source: Dissertation Abstracts International, Volume: 68-11, Section: B, page: 7189. Adviser: Ronald A. Hites.
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Hauer, Gwen. "Salinity Tolerance of Naked Amoebae from Freshwater, Marine, and Hypersaline Environments." NSUWorks, 2003. http://nsuworks.nova.edu/occ_stuetd/118.
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The current study examines salinity tolerance in naked amoebae. A biodiversity study was conducted in the Salton Sea, an inland lake in southern California, with an average salinity of 44 ‰. Amoebae were also collected from hypersaline ponds around the perimeter of the Sea where salinities averaged 160 ‰. A total of 45 species of amoebae were isolated, about one third of which were new to science. One Salton Sea species, Platyamoeba pseudovannellida n.sp. was found to survived over the range 0 - 150 ‰. A first estimate of abundances of amoebae in the Sea showed that densities could reach 237,120 cells L-1. Many of the isolates were observed to consume cyanobacteria and algae suggesting that amoebae are important regulators of blooms in the Sea, although this was not tested experimentally. Samples from the intertidal zone of a beach, a habitat also subject to salinity fluctuations, provided the first abundances of naked amoebae in sand. Densities ranged between 181 and 8473 amoebae cm-3, again suggesting that amoebae are important micrograzers in this challenging environment. From the aforementioned studies, 6 clones of amoebae were isolated for salinity tolerance experiments (2 marine beach isolates, 2 Salton Sea isolates, and 2 hypersaline pond isolates). A seventh clone, Acanthamoeba polyphaga, a common freshwater/soil amoeba was obtained from the Culture Collection of Algae and Protozoa (CCAP). The experiments compared the effects of gradual versus no acclimatization and used growth rate and culture yield as indices of effect. Generally, amoebae were tolerant over a wide range of salinity conditions and were not markedly influenced by pre-conditioning to salinity regimes. Acanthamoeba grew in 0 -12 ‰, marine clones 2 and 3 in 0 - 110 ‰, Salton Sea clones 4 and 5 in 0 - 150 ‰, and the hypersaline clones 6 and 7 in 0 - 270 ‰ salt. The results suggest that most amoebae are essentially unaffected in terms of growth and yield by moderate and severe salinity changes. The survival and activity of large populations of amoebae in sites subject to salinity challenges suggest that they should be considered in future studies designed to understand their as yet undefined ecological role.
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Murdock, Robert Neil. "The transport, behaviour and fate of radionuclides in the freshwater environment." Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317144.
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Sutton, Rowan. "Patterns of transport in the middle atmosphere." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259822.
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Mullendore, Gretchen Louise. "Cross-tropopause tracer transport in midlatitude convection /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/10061.
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Welch, Wendell Tyler. "Nonlinear baroclinic adjustment and wavenumber selection as a mechanism for atmospheric heat transport /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/6771.
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Wearing, Malcolm Jamieson. "Modelling of pollution transport in small tidal harbours." Thesis, University of Salford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366001.
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Kulan, Abdulhadi. "Atmospheric Production and Transport of Cosmogenic 7Be and 10Be." Doctoral thesis, Uppsala universitet, Institutionen för geovetenskaper, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7965.
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This thesis deals with the atmospheric distribution of the cosmogenic isotopes 7Be (half-life 53 days) and 10Be (half-life 1.51 million years) as well as the anthropogenic isotope 137Cs (half-life 30 years) in aerosols and precipitation. Samples covering continuous or selected parts of the period 1972-2005 in Sweden and Europe are evaluated with respect to production, air mass transport and fallout processes. Such information is valuable in assessing the potential of these isotopes as indicators of air mass mixing and solar modulation factors that affect climate change. The results of 7Be and 10Be show seasonal variability and an 11-year cyclic pattern which is anti-correlated with the solar activity. Variations in seasonal trends of 7Be and 137Cs in aerosols during the post- and pre-Chernobyl period reflect tropospheric influence from 137Cs-heavily contaminated regions. A clear latitude dependence is observed in our beryllium isotope data where highest fallout is found in mid-latitudes compared to high and low latitude regions in the Northern hemisphere. This pattern reflects the general air mass circulation in the troposphere. However, stratospheric air mass influence was also identified in mainly single events and through tropopause folding during spring-summer seasons. The ratio of 10Be/7Be is used to estimate effects of air mass transport on production signal. The results show ratios between 1 and 3, much higher than the theoretically predicted value (0.6) in the atmosphere, which suggests contribution from 7Be-depleted (old) air masses. The relationship between monthly 7Be atmospheric activity and Total Fractional Cloud Cover (TFCC), collected from satellite imagery, over Sweden for the years (1991-2000) indicates a negative seasonal correlation. This observation can be related to depletion of aerosol from the atmosphere due to trapping in clouds.
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Bozorg, Magham Amir Ebrahim. "Atmospheric Lagrangian transport structures and their applications to aerobiology." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/56482.
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Exploring the concepts of long range aerial transport of microorganisms is the main motivation of this study. For this purpose we use theories and concepts of dynamical systems in the context of geophysical fluid systems. We apply powerful notions such as finite-time Lyapunov exponent (FTLE) and the associated Lagrangian coherent structures (LCS) and we attempt to provide mathematical explanations and frameworks for some applied questions which are based on realistic concerns of atmospheric transport phenomena. Accordingly, we quantify the accuracy of prediction of FTLE-LCS features and we determine the sensitivity of such predictions to forecasting parameters. In addition, we consider the spatiotemporal resolution of the operational data sets and we propose the concept of probabilistic source and destination regions which leads to the definition of stochastic FTLE fields. Moreover, we put forward the idea of using ensemble forecasting to quantify the uncertainty of the forecast results. Finally, we investigate the statistical properties of localized measurements of atmospheric microbial structure and their connections to the concept of local FTLE time-series.
Results of this study would pave the way for more efficient models and management strategies for the spread of infectious diseases affecting plants, domestic animals, and humans.Ph. D.
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Mulholland, David Paul. "Martian dust lifting, transport and associated processes." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:a94d810a-5c55-4b7e-84b4-04d4f3b4f191.
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The dust lifting capacity of the UK Mars General Circulation Model has been extended through the development of a new wind stress lifting parameterisation, and the simulation of a finite, variable surface dust layer. This second addition, which was represented by the use of lifting thresholds that were adjusted at each surface gridpoint in response to the removal or deposition of dust, led to enhanced variability in the timing and peak magnitude of major dust storms produced in the model. These dust storms were realistic in many respects, and the observed global dust storm frequency of occurrence of roughly one in every three years was approximately reproduced by the model, but an artificial threshold decrease rate was required to maintain dust lifting on a multiannual timescale - this was believed to be due to inaccuracies in the net cross-equatorial dust flux, which showed a strong bias towards the northern hemisphere. Significant changes were seen in model dust lifting rates when the influence of a heterogeneous surface roughness length was included in the wind stress scheme, and the need for more sophisticated sub-gridscale methods in future dust lifting schemes, to cope with this and other effects, was noted. The inclusion of radiatively active water clouds in model runs also affected dust lifting rates, particularly in the vicinity of the polar caps in autumn, winter and spring. The dynamics behind the formation of small, cap-edge dust storms during these periods were examined in detail, and it was found that a cessation in dust lifting activity that occurs around winter solstice does so due to a combination of the radiative effects of global dust loading and polar hood ice clouds, and zonal variations in midlatitude topography. The direct interaction between dust and ice, in the form of nucleation and scavenging, was investigated. It was found that scavenging by water ice, if it is suitably efficient, could significantly reduce the dust content of the winter polar regions. However, the dust and ice vertical profiles measured in the aphelion cloud belt by Mars Climate Sounder were not reproduced by the model with any of the possible scavenging efficiencies used. It appears that scavenging cannot provide an explanation for the existence of sharply defined, elevated dust layers at low latitudes.
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Arnold, Neil F. "Tracer transport in the middle atmosphere." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.279884.
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Kjellsson, Joakim. "Atmospheric & Oceanic Applications of Eulerian and Lagrangian Transport Modelling." Doctoral thesis, Stockholms universitet, Meteorologiska institutionen (MISU), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-97348.
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This thesis presents several ways to understand transports of air and water masses in the atmosphere and ocean, and the transports of energy that they imply. It presents work using various kinds of observations as well as computer simulations of the atmosphere and oceans. One of the main focuses is to identify similarities and differences between models and observations, as well as between different models. The first half of the thesis applies Lagrangian methods to study flows in the atmosphere and oceans. Part of the work focuses on understanding how particles follow the currents in the Baltic Sea and how they disperse. It is suggested that the commonly used regional ocean model for the Baltic Sea, RCO, underestimates the transport and the dispersion of the particles, which can have consequences for studies of e.g. biogeochemistry as well as for operational use. A similar methodology is used to study how particles are transported between the tropics and mid-latitudes by the large-scale atmospheric circulation. It is found that the mass transport associated with northbound and southbound particles can cancel in the zonally averaged circulation, and we propose that the degree of cancellation depends on the method of averaging. The latter half of the thesis focuses on Eulerian stream functions and specifically a thermodynamic stream function that combines the zonal and meridional circulations of the atmosphere into a single circulation. The results are used to study the inter-annual variability of the intensity and thermodynamic properties of the global atmospheric circulation. A significant correlation to ENSO variability is found both in reanalysis and the EC-Earth coupled climate model. It is also shown that a set of models from the CMIP5 project show a slowdown of the atmospheric circulation as a result of global warming and associated changes in near-surface moisture content and upper-level radiative cooling.Denna avhandling presenterar olika metoder för att studera datormodeller av atmosfä- ren, haven, och klimatsystemet. Metoderna använder såväl Lagrangeska synsätt dvs att betrakta atmosfären eller haven som individuella partiklar i rörelse, som Eulerska synsätt där atmosfären och haven ses som gas eller vätska i rörelse. I artikel 1 sjö- sätts ett antal “surface drifters” i Östersjön som driver fritt med havsströmmarna och vars hastighet mäts av satelliter. Genom att modellera Lagrangeska partiklars rörelser i Östersjön och jämföra med dessa “surface drifters” kan det visas att datormodeller kan underskatta både medelhastigheten av partiklarna samt deras utbredning. I ar- tikel 2 simuleras luftmassornas rörelser mellan tropikerna och mellanbreddgraderna (∼ 45◦N/S). Ett medelvärde över all longituder tenderar att ignorera betydande mass- och energitransporter mellan tropikerna och mellanbredderna, och dessa kvantifieras i detalj i artikel 2. Artiklarna 3 och 4 presenterar en metod för att studera atmosfärens storskaliga rörelser utifrån ett termodynamiskt perspektiv där luftmassornas värme och fukt studeras. Det visas att variationer ytvattentemperatur vid ekvatorn i Stilla havet kan få atmosfären att, i ett globalt medelvärde, bli fuktigare och varmare samtidigt som masstransporter- na saktar ner. På samma sätt visas att en global uppvärmning till följd av ökade utsläpp av växthusgaser kan få atmosfären att bli varmare, fuktigare och att masstransporterna kan sakta ner.
At the time of the doctoral defence the following papers were unpublished and had a status as follows: Paper 3: In press; Paper 4: Manuscript.
BalticWay
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Traub, Michael Andreas. "Lagrangian transport evaluation of atmospheric chemistry in the Mediterranean region." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=975874489.
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Heaviside, Clare Helen. "Coupling of oceanic and atmospheric heat transport in the tropics." Thesis, Imperial College London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.508323.
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Barlow, Janet F. "Turbulent transport of space charge in the atmospheric surface layer." Thesis, University of Reading, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270265.
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Jöckel, Patrick. "Cosmogenic 14 CO as tracer for atmospheric chemistry and transport." [S.l. : s.n.], 2001. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB8986380.
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Wilcock, Peter R. (Peter Richard) 1953. "Bed-load transport of mixed-size sediment." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14866.
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Martin, William R. "Transport of trace metals in nearshore sediments." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/15270.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1985.MICROFICHE COPY AVAILABLE IN ARCHIVES AND LINDGREN.
Vita.
Bibliography: leaves 292-301.
by William R. Martin.
Ph.D.
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Schurr, Naomi D. (Naomi Danika). "Climatic influences on hillslope soil transport efficiency." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/90655.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 36-38).
The soil transport coefficient D represents the relationship between local topographical gradient and soil flux in the landscape evolution model. This work presents new estimates of the soil transport coefficient D at 9 sites and compares them, along with a compilation of 16 previously published estimates of D, against three climate proxies (mean annual precipitation, aridity index, and mean annual temperature) with the goal of characterizing climatic influences on soil transport efficiency. The new measurements were performed at sites that extend the range into both drier and wetter climates than those published. Together the data suggest that D increases with mean annual precipitation and aridity in dry climates, and levels off or decreases gradually in wetter climates.
by Naomi D. Schurr.
S.B.
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Yates, Christopher Alan. "Characterising dissolved organic matter flux in UK freshwater systems : sources, transport and delivery." Thesis, University of Reading, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.631698.
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Dissolved organic matter (DOM) is a significant component of carbon (C), nitrogen (N) and phosphorus (P) flux from source to sea. This thesis presents the results of an investigation into the seasonal and spatial variability of DOM character, and flux of DOM relative to inorganic N and P, in two contrasting lowland UK catchments: the chalk-dominated River Wylye and peat-dominated Millersford Brook. Each catchment was sampled weekly at a total of 14 sampling locations, with daily sampling at three sites in each catchment. Dissolved organic carbon (DOC), all N species, P fractions, and both chromophoric and fluorescent dissolved organic matter were measured over a two year period (2010-2012). Contributing nutrient source areas varied between catchments. In the Wylye catchment nutrient fluxes were strongly influenced by groundwater and diffuse agricultural inputs. Point source discharges from sewage treatment facilities contributed significantly to instream loading in the lower reaches with inorganic fractions dominating the nutrient chemistry across the catchment. Chromophoric dissolved organic matter (CDOM) measurements related to aromaticity and molecular weight were low across the Wylye catchment, but significantly elevated during periods of high flow indicating the flushing of material with a greater aromatic content from the surrounding catchment. In contrast, Nand P data from Millersford Brook was dominated by organic Nand P respectively with DOC significantly elevated compared to the Wylye catchment. As a result of catchment geology and varying nutrient source areas CDOM measurements suggested both waters to differ significantly in their DOM aromatic content. No obvious temporal variation instream was observed during the monitoring period however, data from storm event sampling found high flow events responsible for the delivery of material with a low aromatic content when compared to CDOM under baseflow conditions. Results presented here give further insight into the compositional variations in the bulk chemistry within and between two contrasting lowland catchments, suggesting significant differences in DOM composition across study areas
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Moriizumi, Jun, Takehisa Ohkuraa, Shigekazu Hirao, Yuki Nono, Hiromi Yamazawa, Yoon-Shin Kim, Qiuju Guo, Hitoshi Mukai, Yasunori Tohjima, and Takao Iida. "Continuous Atmospheric Radon-222 Concentration Observation in East Asia." American Institite of Physics, 2008. http://hdl.handle.net/2237/12040.
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Koh, Tieh-Yong 1972. "Isentropic diagnostics of mid-latitude circulation and transport." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/59649.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2001.Includes bibliographical references (p. 279-287).
This thesis examines the mid-latitude circulation and tracer transport using zonal average isentropic diagnostics. The Underworld (i.e. the region roughly below the 300K-isentrope) is targeted by our research. Currently, there is a lack of rigorous and consistent theoretical formalism to deal with isentropes that intersect the Earth's surface. In this thesis, we develop such a formalism and use it to address three main questions: (1) How is the mean circulation forced by the eddies in the region - dubbed "surface zone" - where isentropes intersect the surface in the longitude-height plane? (2) What are the pathways of global chemical transport due to mean circulation and eddies? (3) How are eddy chemical and PV transports related? A primitive-equation model on a sphere, equipped with simple physical parametrizations and on-line tracer transport, is used to investigate these questions. We tackle question (1) by looking for explanations in terms of angular momentum balance and surface heat transport. Our results show that equatorward PV flux forces a poleward mean flow in the warmer region of the surface zone. In the colder region, an equatorward mean flow is forced by eastward surface form drag, which is attributed to poleward eddy heat, flux at the surface.
(cont.) We also evaluate and modify the kinematic explanation put forth by Held and Schneider (1999). As regards question (2), we found that idealized chemical tracers released into the planetary boundary layer (PBL) are transported equatorward in the surface zone by the mean circulation and the eddies. Some are recirculated polewards by the eddies, both along the surface and along isentropes (in the absence of latent heat release). Mid-tropospheric tracers are adiabatically transported by eddies into the mid-latitude PBL. Question (3) is addressed using a diffusive formulation for isentropic eddy transport. The eddy-diffusion coefficients for several idealized chemicals of lifetime 20 days agree rather well, demonstrating the usefulness of the parametrization. But the eddy-diffusion coefficient for PV, while showing the same enhancement at steering levels, is sufficiently different from chemical eddy-diffusion coefficients to imply that diabatic heating is significant in a baroclinic wave.
by Tieh-Yong Koh.
Ph.D.
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Darbyshire, Megan Louise. "The measurement and transport of volatile organic compounds in the troposphere." Thesis, University of Reading, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270934.
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Mayer, Jens-Christopher. "Transport processes of reactive trace gases in the atmospheric boundary layer." kostenfrei, 2008. http://opus.ub.uni-bayreuth.de/volltexte/2009/573/.
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Kreuger, Jenny. "Pesticides in the environment : atmospheric deposition and transport to surface waters /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5485-9.pdf.
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Smy, Louise Ann. "Atmospheric transport and critical layer mixing in the troposphere and stratosphere." Thesis, University of St Andrews, 2012. http://hdl.handle.net/10023/2538.
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This thesis aims to improve the understanding of transport and critical layer mixing in the troposphere and stratosphere. A dynamical approach is taken based on potential vorticity which has long been recognised as the essential field inducing the flow and thermodynamic structure of the atmosphere. Within the dynamical framework of critical layer mixing of potential vorticity, three main topics are addressed. First, an idealised model of critical layer mixing in the stratospheric surf zone is examined. The effect of the shear across the critical layer on the critical layer evolution itself is investigated. In particular it is found that at small shear barotropic instability occurs and the mixing efficiency of the critical layer increases due to the instability. The effect of finite deformation length is also considered which extends previous work. Secondly, the dynamical coupling between the stratosphere and troposphere is examined by considering the effect of direct perturbations to stratospheric potential vorticity on the evolution of midlatitude baroclinic instability. Both zonally symmetric and asymmetric perturbations to the stratospheric potential vorticity are considered, the former representative of a strong polar vortex, the latter representative of the stratospheric state following a major sudden warming. A comparison of these perturbations gives some insight into the possible influence of pre or post-sudden warming conditions on the tropospheric evolution. Finally, the influence of the stratospheric potential vorticity distribution on lateral mixing and transport into and out of the tropical pipe, the low latitude ascending branch of the Brewer-Dobson circulation, is investigated. The stratospheric potential vorticity distribution in the tropical stratosphere is found to have a clear pattern according to the phase of the quasi-biennial oscillation (QBO). The extent of the QBO influence is quantified, by analysing trajectories of Lagrangian particles using an online trajectory code recently implemented in the Met Office's Unified Model.
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Wilson, Julian John Nash. "Long range atmospheric transport in probabilistic risk assessment for nuclear installations." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47716.
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Nisancioglu, Kerim Hestnes 1975. "Modeling the impact of atmospheric moisture transport on global ice volume." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/16703.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2004.Includes bibliographical references (leaves 137-154).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Following Milankovitch's original hypothesis most model studies of changes in global ice volume on orbital time scales have focused on the impact of ablation on ice sheet mass balance. In most cases, poleward moisture flux is fixed and accumulation of snow only depends on local temperature. In this study, a simple coupled atmosphere-ice process model is introduced. An improved representation of the atmospheric hydrological cycle is included, and accumulation is related to the meridional flux of moisture by large scale baroclinic eddies. The ice sheets in the Northern Hemisphere respond to both precession and obliquity frequencies when the model is forced with seasonal insolation. Obliquity variations are introduced by the impact of earth's tilt on the meridional temperature gradient and the poleward flux of moisture, whereas precession governs surface melting by regulating summer temperatures. The response of the ice sheet to obliquity and precession is comparable, and significantly smaller than what is observed in the oxygen isotope record of the late Pliocene and early Pleistocene (2.7 - 0.8 Ma BP). This suggests that in order to successfully reproduce the strong 41 Ka periodicity observed in the record, other mechanisms must be involved such as nonlinear self-sustained, or stochastic processes, or alternatively the obliquity dominated signal originates from Antarctica. In Antarctica the seasonal cycle is damped due to the large thermal mass of the southern ocean, and surface melt is insignificant. Both of these factors reduce the influence of precession in regulating ice volume. Instead, the mass balance is dominated by accumulation and calving, thereby enhancing the role of obliquity in controlling ice volume.
by Kerim Hestnes Nisancioglu.
Ph.D.
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Bitane, Rehab. "Transport and density fluctuations in disordered systems : applications to atmospheric dispersion." Nice, 2012. http://www.theses.fr/2012NICE4079.
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Le transport turbulent de particules est un phénomène important qui intervient dans de nombreux processus naturels et industriels. Comprendre ses propriétés et, en particulier, la création de grandes fluctuations de densité, est fondamental pour améliorer les modèles et affiner les prévisions. Cela représente de nombreux enjeux économiques, environnementaux et de santé. Une étude Lagrangienne de la séparation de paires de traceurs a été menée en s'appuyant sur l'analyse des données de simulations numériques à très haute résolution. Elle a permis de souligner les défaillances des approches de type champ moyen qui sont à la base des modèles les plus couramment utilisés. Pour la séparation, on constate que la transition entre le régime balistique de Batchelor et le régime explosif de Richardson a lieu à des temps données par le temps moyen de dissipation de l'énergie cinétique turbulente. Aussi, il est montré que la loi de Richardson peut s'interpréter comme un comportement diffusif des différences de vitesse. Des arguments phénoménologiques permettent d'interpréter cet effet par la décorrélation de différences d'accélération et la stationnarité aux temps longs du taux local de transfert d'énergie cinétique. Les moments d'ordres élevés de la séparation et de la vitesse sont aussi étudiés pour aborder la question des «événements violents» dans la distribution des distances. Enfin, un modèle d'éjection de masse est proposé et utilisé pour examiner les fluctuations de la densité de particules lourdes transportées dans un environnement aléatoireThe turbulent transport of particles is an important phenomena which appears in many natural and industrial processes. Understanding its properties, and, in particular, the creation of strong density fluctuations, is fundamental to improve models and refine forecasts. This can lead to significant benefits in issues related to economics, the environmental and health. A Lagrangian study of the tracer pair separation was carried out with the help of high resolution data analysis. This allowed us to point out the weaknesses of the mean-field approaches on which most models are based. For the separation, it is found that the transition from the regime of Batchelor (or ballistic) to that of Richardson (or explosive) occurs at times given by those typical of the turbulent kinetic energy dissipation. It is also found that Richardson’s law can be reinterpreted in terms of diffusive behaviour of the velocity differences. Phenomenological arguments allow us to explain this effect through the decorrelation of the acceleration differences and the stationarity of the kinetic energy transfer ratio at large times. The high-order moments of both separation and velocity are also investigated to address the question of "violent events" in the distribution of the distances. Finally, a one-dimensional mass ejection model is proposed and used to examine the density fluctuations of heavy particles transported by the random environment
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Mansfield, Megan (Megan L. ). "Analysis of Pluto's light curve to detect volatile transport." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/114102.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 65-66).
Changes in the volatile distribution on Pluto's surface and in its atmosphere are expected to occur over its orbital path due to varying surface insolation[14]. To investigate these changes, a model was created to synthesize light curves of Pluto, given the viewing geometry and surface albedo distribution. Using an initial surface albedo distribution based on images taken by New Horizons, changes in the light curve mean magnitudes and amplitudes over time were compared to the smallest magnitude changes detectable by a variety of telescopes. The model predicts that yearly observations on a large ground-based telescope, such as the 6.5-meter Magellan telescopes, could observe magnitude changes due to both changes in viewing geometry and surface albedo changes. The model can be compared to future observations to estimate how much surface albedo change is necessary to produce the observed light curves, and can therefore be used to link observational data to physical changes on Pluto's surface and the methods of volatile transport responsible for those changes.
by Megan Mansfield.
S.B.
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Fry, Virginia Ann. "Tidal velocity asymmetries and bedload transport in shallow embayments." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/52896.
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Ganachaud, Alexandre Similien 1970. "Large scale oceanic circulation and fluxes of freshwater, heat, nutrients and oxygen." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/58541.
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Thesis (Sc. D.)--Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), February 2000.Includes bibliographical references (p. 250-266).
A new, global inversion is used to estimate the large scale oceanic circulation based on the World Ocean Circulation Experiment and Java Australia Dynamic Experiment hydrographic data. A linear inverse "box" model is used to combine consistently the transoceanic sections. The circulation is geostrophic with an Ekman layer at the surface and oceanic layers defined by neutral surfaces. Near-conservation of mass, salt and top-to-bottom silica is required and, in addition, heat and the phosphate-oxygen combination (170[PO 4]+[0 2]) are conserved in layers that are not in contact with the surface. A globally-consistent solution is obtained for a depth-independent adjustment to the thermal wind field, freshwater flux divergences, the Ekman transport, and the advective and diffusive dianeutral fluxes between layers. A detailed error budget permits calculation of statistical uncertainties, taking into account both the non-resolved part of the solution and the systematic errors due to the temporal oceanic variability. The estimated water mass transports during the WOCE period (1985-1996) are generally similar to previous published estimates. However, important differences are found. In particular, the inflow of bottom waters into the Pacific Ocean is smaller than in most previous estimates. Utilization of property anomaly conservation constraints allows the estimation of significant dianeutral diffusivities in deep layers, with a global average of 3 ± 1cm 2 s-1 north of 30'S. Dianeutral transfers indicate that about 20 Sv of bottom water is formed in the Southern Ocean. Significant oceanatmosphere heat fluxes are found, with a global heating of 2.3 ± 0.4 PW in the tropical band and a corresponding cooling at high latitudes. The signature of a large-scale average export production is found for nutrients in several temperate regions. Despite the large uncertainties, the production magnitudes are consistent with independent measurements from sediment traps and isotopic data. Net nutrient sources or sinks are found in several regions, suggesting either transport of dissolved organic matter or a seasonal alias. Oxygen indicates large exchanges with the atmosphere, with intake at high latitudes and outgassing/remineralization at low latitudes.
by Alexandre Similien Ganachaud.
Sc.D.
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Gilliland, Alice Brien. "The potential influences of ENSO on interhemispheric transport." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/26279.
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Lingenfelser, Gretchen Scott. "The use of Long-Lived Tracer Observations to Examine Transport Characteristics in the Lower Stratosphere." W&M ScholarWorks, 2000. https://scholarworks.wm.edu/etd/1539626247.
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Olson, John Forest. "Two-fluid flow in sedimentary rock : complexity, transport, and simulation." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11182.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1996.Includes bibliographical references (leaves 95-102).
by John Forest Olson.
Ph.D.
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Siddiqi, Gunter 1964. "Transport properties and mechanical behavior of synthetic calcite-quartz aggregates." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/58163.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1997.Includes bibliographical references (leaves 233-244).
by Gunter Siddiqi.
Ph.D.
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Omidvarborna, Hamid. "Combustion Chemistry of Biodiesel for the Use in Urban Transport Buses: Experiment and Modeling." University of Toledo / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1464863574.
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Wen, Deyong. "Modelling of Atmospheric Mercury Emission, Transport, Transformation and Deposition in North America." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/2959.
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A modelling study was conducted to explore the emission, transport, transformation and deposition behaviour of atmospheric Hg. A detailed natural Hg emission model was developed to estimate the natural Hg emissions from soil, water and vegetation. U. S. Environmental Protection Agency (EPA) Community Multiscale Air Quality (CMAQ) Hg model system was improved by incorporating the detailed treatment of natural Hg emissions, adopting boundary conditions from a global Hg model (Seigneur et al. , 2004) and including the calculation of the dry deposition velocity of elemental Hg. The natural Hg emission model and the improved CMAQ-Hg model were validated with some measurements and then applied to North America for a whole year (2002).
A detailed natural Hg emission model was developed in this study. This model made use of detailed soil Hg concentration measurements, meteorological data and soil conditions to estimate Hg emissions from soil, water and vegetation. The influence of snow cover and low temperature was also considered in the model. This model was then applied to simulate one-year natural Hg emissions in North America in 2002. The modelled results, compared to some reported natural Hg emission measurements, demonstrated a strong simulation ability. The spatial and temporal variations of emission fluxes were examined through numerical simulations. A pronounced diurnal cycle and a seasonal cycle were found in the emissions from most land uses. Compared with summer, natural Hg emission was significantly limited in winter. Simulation results showed that about 229 metric tons of total natural Hg emission, 1. 8 times anthropogenic Hg emission, was emitted from the simulation domain in 2002.
U. S. EPA CMAQ Hg model system was improved and then applied to simulate the emission, transport, transformation and deposition of atmospheric Hg in North America for the year 2002. The simulated results were compared with measured hourly Total Gaseous Hg (TGM) for 3 sites. The good agreement between them demonstrated the good performance of this improved model in modelling the behaviour of emission, transport, transformation and deposition of atmospheric Hg. Hg budget and net evasion of Hg in North America were also investigated.
A sensitivity analysis was conducted to assess the effects of emissions, including Hg and non-Hg emissions, on the air concentration and deposition of atmospheric Hg. The results indicated that ambient concentration of TGM was much more sensitive to Hg emissions than non-Hg emissions. Natural Hg emission was more significant than anthropogenic emission to affect ambient concentration of TGM, illustrating natural Hg emission is a key factor influencing TGM ambient concentration. Unlike TGM concentration, Hg dry deposition was not only sensitive to Hg emissions but also to non-Hg emissions such as VOCs and NOx. Anthropogenic Hg emission, natural Hg emission and NOx emission had almost the same effect on total dry deposition of Hg. The results also illustrated that Hg wet deposition was only sensitive to non-Hg emissions such as NOx and VOCs, especially of VOCs emission. Because of the inverse effect of VOCs on Hg wet deposition, reducing NOx emission should be an ideal solution to mitigate Hg wet deposition. A possible pathway through which atmospheric Hg was greatly affected by emissions changes was identified: emissions of pollutants, especially VOCs and NOx, greatly affect the level of OH in the atmosphere; OH influences the concentration and deposition of Hg by significantly affecting the gas phase reaction between Hg(0) and OH.
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Pöllänen, Roy. "Nuclear fuel particles in the environment : characteristics, atmospheric transport and skin doses." Helsinki : University of Helsinki, 2002. http://ethesis.helsinki.fi/julkaisut/mat/fysik/vk/pollanen/.
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Li, Can. "Emissions, transport, and evolution of atmospheric pollutants from China an observational study /." College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/8849.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2008.Thesis research directed by: Dept. of Atmospheric and Oceanic Sciences. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Huang, Gang. "Numerical simulation of solid particle transport in atmospheric boundary-layer over obstacles." Thesis, Ecully, Ecole centrale de Lyon, 2015. http://www.theses.fr/2015ECDL0049/document.
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Afin de mieux comprendre les mécanismes liés à l’érosion du sol sous l’effet du vent, le transport de particules solides dans un écoulement de couche limite turbulente à l’échelle d’une soufflerie est étudié à l’aide de simulations numériques. La présence d’une ou plusieurs collines Gaussiennes au sol permet d’étudier les effets de la topographie sur le transport, le dépôt et la réémission de particules solides. L’écoulement du fluide porteur est résolu par la Simulation des Grandes Échelles (SGE). Des modèles de paroi pour la vitesse du fluide sont implémentés afin de mieux représenter l’écoulement proche d’une colline. Le mouvement des particules est pris en compte par un suivi Lagrangien. Des modèles d’envol et de rebond sont développés et utilisés pour prendre en compte l’émission et l’impact au sol des particules. Dans la première partie, l’écoulement au-dessus de collines transversales est simulé et validé par des comparaisons avec différentes expériences. Selon Oke [1988], l’écoulement dans la canopée urbaine peut être schématiquement caractérisé par différents régimes en fonction du positionnement relatif des obstacles. Ce concept est appliqué au cas des dunes, assimilées à des collines dans notre étude. L’accent est mis sur la zone de recirculation (ZR) formée derrière ces collines. Les variations de la ZR sont examinées en fonction de différents paramètres dont la configuration des collines et le nombre de Reynolds. De plus, une étude portant sur la sous couche rugueuse est effectuée de façon à déterminer l’effet de la rugosité due à la couche de particules solides au sol. La seconde partie du travail porte sur la simulation des particules au-dessus des collines. L’objectif est l’amélioration des modélisations concernant l’envol, le rebond et le couplage entre le fluide et les particules. Un premier travail de validation est réalisé en utilisant le modèle complet de transport des particules solides. En particulier, l’évolution du flux d’émission des particules, estimé par le modèle d’envol, en fonction du nombre de Shields, donne des résultats comparables aux modèles classiques de saltation et aux expériences de la littérature. Au-dessus des collines, le transport des particules solides est étudié par des profils de concentration et de vitesse moyenne. Pour analyser les résultats, deux cartographies sont réalisées. La première donne l’intensité des événements locaux et instantanés qui seraient à l’origine de l’évacuation des particules piégées au sein de la ZR. La seconde montre la distribution des particules déposées au sol. Ces résultats permettent d’identifier des zones sujettes à l’érosion et à l’accumulation autour des collines. Enfin, les flux des particules piégées et déposées à l’intérieur de la ZR sont quantifiés et comparés aux flux des particules émises en amont. Ces flux, bien que faibles par rapport au flux entrant, contribueraient aux migrations des dunes et à l’avancée des désertsThe transport of solid particles inside a laboratory-scale turbulent boundary-layer is studied by numerical simulations, to obtain a better understanding of the mechanisms associated with wind erosion of soil. The presence of one or several Gaussian hills allows a study of the topographic effects on the transport, deposition and re-emission of solid particles. The carrier fluid motion is resolved in a Large Eddy Simulation (LES). Wall models are implemented to better account for the effects of turbulent flow near the terrain. Particle trajectories are calculated using a Lagrangian tracking. Take-off and rebound models are developed in order to take into account particle emissions and impacts at the wall. In the first part, the flow over transversal Gaussian hills is simulated and validated by comparison with different experiments. According to Oke [1988], the flow inside an urban canopy can be schematically characterised into different flow regimes depending on the relative localisation of the obstacles at the ground. This concept is applied to the case of sand dunes, assimilated to 2D hills in this study. The focus is on the recirculation zone (RZ) on the lee side, which has the characteristic of increasing the residence time and the interaction fluid/particle in general, particle trapping and deposition in particular. The variations of RZ with different hill geometries and Reynolds numbers are examined. A study on the roughness sublayer is conducted in order to determine the roughness effects due to the layer of solid particles on the wall. The second part of the work is devoted to the simulation of solid particle transport over the Gaussian hills. The objective is to improve the modelling of particle take-off, rebound and the two-way coupling between the fluid and the particle. A first work of validation is conducted by using the complete model of solid particle transport developed in this thesis. In particular, the evolution of particle emission flux predicted by the take-off model is in accordance with classical saltation models and experiments from the literature. Over the Gaussian hills, analysis of particle transport is conducted using concentration and mean velocity fields. Two mappings are realised. The first indicates the intensity of the local and instantaneous flow structures that arguably regulate the re-entrainment of particles trapped inside the RZ. The second shows the accumulation of particles on the wall. These results highlight zones prone to wind erosion and particle deposition around the hills. Last but not least, the fluxes of particle trapping and deposition inside the RZ are quantified and compared to the incoming flux from upstream. These fluxes, albeit relatively weak in comparison to the incoming one, contribute potentially to dune migrations and desertification
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Koster, Randal Dean. "Tracer water transport and subgrid precipitation variation within atmospheric general circulation models." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14673.
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