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Dissertations / Theses on the topic 'Boundary layer (Meteorology)'

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Published: 4 June 2021
Last updated: 29 July 2024

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1

Johansson, Cecilia. "Influence of External Factors on the Turbulence Structure in the Atmospheric Boundary Layer." Doctoral thesis, Uppsala University, Department of Earth Sciences, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3221.

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The theory used in today’s weather- and climate models to describe processes near the earth’s surface, i.e. transport of heat, moisture and momentum between the ground and the atmosphere, is based on the idea that only local factors are important, such as temperature and wind speed near the ground. However, from measurements made at two sites, one agricultural and one marine, it has been found that large eddies, which are related to the convective boundary layer height, influence the turbulence structure near the ground during unstable conditions more than previously realized. Especially the momentum transport is affected. The large eddies have similar size over land and over the sea, typically 1000 m. The important difference being that over land diurnal variation plays a fundamental role; over the sea such variations are typically absent.

From the marine site it has also been found that the turbulence structure of the temperature field over the Baltic Sea is very different from over land. Instead of having a height dependence as expected from theory, the temperature structure seems to be constant with height within the surface layer.

Typically, the heat flux over the sea is smaller than over land during convective conditions. This gives rise to a turbulence transport regime which is fundamentally different from that observed during daytime convective conditions over land.

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2

Stevens, David Eric. "An adaptive multilevel method for boundary layer meteorology /." Thesis, Connect to this title online; UW restricted, 1994. http://hdl.handle.net/1773/6776.

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3

MacKinnon, Andrew David. "VHF Boundary Layer Radar and RASS." Title page, abstract and table of contents, 2001. http://hdl.handle.net/2440/37807.

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This thesis describes the refinements, modifications and additions to a prototype Very High Frequency (VHF) Boundary Layer (BL) Spaced Antenna (SA) radar initially installed at the University of Adelaide's Buckland Park field site in 1997. Previous radar observations of the lowest few kilometres of the atmosphere, in particular the Atmospheric Boundary Layer, have used Ultra-High Frequency (UHF) radars. Unlike VHF radars, UHF radars are extremely sensitive to hydro-meteors and have difficulty in distinguishing clear-air echoes from precipitation returns. The advantages and requirements of using a VHF radar to observe the lowest heights is discussed in conjunction with some of the limitations. The successful operation of the system over long periods has enabled in-depth investigation of the performance of the system in a variety of conditions and locations. Observations were made from as low as 300m and as high as 8 km, dependent upon conditions. Comparisons between the radar and alternative wind measuring devices were carried out and examined. The antenna system of the radar is a critical component which was analysed in depth and subsequently re-designed. Through the use of numerical models and mea- surements, evaluation of different designs was accomplished. Further calibration of the remaining components of the full system has enabled estimations of the absolute received power. Additional parameters which can be derived with a calibrated radar were compared with values obtained by other authors, giving favourable results. Full Correlation Analysis (FCA) is the predominant technique used in this work. A brief discussion of the background theory and parameters which can be measured is described. A simple one-dimensional model was developed and combined with a 'radar backscatter model' to investigate potential sources of errors in the parameters determined using FCA with the VHF Boundary Layer Radar. In particular, underes- timations in the wind velocity were examined. The integration of a Radio Acoustic Sounding System (RASS) to obtain tempera- ture profiles is discussed. The theory of RASS measurements including the limitations and considerations which are required for the VHF BL radar are given. The difficulties encountered trying to implement such a system and the subsequent success using a Stratospheric Tropospheric (ST) Profiler in place of the BL radar is presented. Taken as a whole this thesis shows the success of the VHF BL to obtain mea- surements from as low as 300m. The validation of this prototype radar provides an alternative and, in certain situations, a superior device with which to study the lower troposphere.
Thesis (Ph.D.)--Department of Physics and Mathematical Physics, 2001.
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4

Potvin, Guy. "The application of RASS in urban boundary layer meteorology." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0019/NQ44556.pdf.

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5

Carlsson, Magnus. "The stable boundary layer over the ice covered Bothnian Bay." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-392449.

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The turbulence structure in a stable boundary layer over ice has been studied. Data from the Bothnian Bay, measured during the BASIS field campaign in February/March 1998, have been used. Turbulence as well as wind- and temperature profiles were measured at three sites. The sites were Umeå at the Swedish East Coast, Kokkola at the Finnish West Coast and the ship R/V Aranda outside the Finnish coast.  Turbulence parameters are studied in terms of their stability dependence. At stronger stability σu/u*, σv/u* and σw/u* all increase with stability. At near neutral stratification σw/u* increases with height. A linear dependence of the pressure gradient scale ln(zf/u*) is seen for σw/u* in the interval 0<z/L<0.1. σw/σu  first increases and then decreases with stability in agreement with earlier results. From the results it is concluded that the turbulence structure in the stable boundary layer over ice follows the Monin-Obukhov similarity theory. In some of the studied parameters the results from the Umeå site deviate from the other two. Since Umeå has a larger measuring height (10 m) than the other two (2 and 3.5 m) the conclusion is drawn that the surface layer height is lower than 10 m.  Data from the Umeå site has been used to study atmospheric phenomena that develop over the marginal ice zone. During two days two phenomena were observed that were triggered by the temperature difference between ice and water - a stable internal boundary layer and an ’ice breeze’ similar to the land breeze. The development of the internal boundary layer has been studied by using an expression for internal boundary layer height. A criterion earlier used to forecast the sea breeze has been shown to be suitable also for the ’ice breeze’.
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Andrae, Ulf. "Turbulence structures in a non-stationary marine atmospheric boundary layer." Thesis, Uppsala universitet, Meteorologiska institutionen, 1996. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-392332.

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The vertical structure in the coastal marine atmosphere has been investigated using data from aircraft measurements performed along the Blekinge coast. The present data are from the third of October 1990. The main feature is fairly homogeneous horizontal conditions and a subceeing boundary layer which lowers from 600 meters down to about 50 meters during the day. The turbulence were found to be in a decreasing state. The turbulence parameters were normalized using normal stationary scaling, in order to compare with other results.
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7

Anderson, Philip Stuart. "Aspects of the Antarctic boundary layer." Thesis, Lancaster University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239832.

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8

Schafer, Robert. "Tropical island boundary layer structure and development /." [Sydney : University of Technology, Sydney], 1998. http://grison.colorado.edu/Robert/paper/phd.pdf.

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9

Lee-Thorp, Andrew Michael. "The atmospheric boundary layer above the Agulhas current." Master's thesis, University of Cape Town, 1996. http://hdl.handle.net/11427/19455.

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This thesis describes the atmospheric boundary layer above the Agulhas Current using shipboard meteorological measurements and rawinsonde ascents. The juxtaposition of the warm Agulhas Current and cool shelf waters is shown to have far-reaching effects on the overlying atmosphere. Air-sea fluxes of momentum, sensible and latent heat and resultant boundary layer characteristics demonstrate high horizontal inhomogeneity. The results suggest that this inhomogeneity is permanent. The spatial heat flux gradient is reflected in the overlying atmosphere by a transition in stability of the boundary layer and potential cumulus formation from the cool shelf to the warm current. For airflow perpendicular to the Agulhas Current an internal boundary layer was observed to develop at the inshore sea surface temperature front. Onshore-moving air accumulated a significant quantity of moisture during its trajectory over the current. When airflow is parallel to the current an atmospheric moisture front exists along the axis of the inshore sea surface temperature front. The mean thermodynamic structure of the atmosphere was investigated. An inversion capped the boundary layer whilst a second, higher-level subsidence inversion was found which acts to limit the vertical development of cumulus clouds and therefore the redistribution of heat and moisture above the boundary layer. The results presented in this thesis are useful in two ways. The Agulhas Current has frequently been linked to South African climate. This is the first dedicated study which quantifies and characterizes the atmospheric boundary layer in this region. Secondly, maritime airmasses are dramatically modified above the Agulhas Current. The resultant large horizontal inhomogeneity, its vertical extent and permanence suggest that its inclusion is vital to any successful climate model. Atmospheric general circulation models have been criticized for not taking into account regions of strong horizontal inhomogeneity. The results of this thesis support this argument and highlight the need for similar studies. Bibliography: pages 116-123.
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10

Whisenhant, Michelle K. "Turbulence parameterizations for convective boundary layers in high-resolution mesoscale models." Diss., Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Dec%5FWhisenhant%5FPhD.pdf.

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11

Mabey, Deborah L. "Variability of refractivity in the suface layer." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Jun%5FMabey.pdf.

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12

Harris, Brad G. "Analysis of lateral boundary effects on inner domain of COAMPS." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Sep%5FHarris.pdf.

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Thesis (M.S. in Meteorology and Physical Oceanography and M.S. in Applied Mathematics)--Naval Postgraduate School, Sept. 2004.
Thesis advisor(s): Douglas K. Miller, Beny Neta. Includes bibliographical references (p. 83). Also available online.
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13

Van, der Kamp Derek. "Ceilometer observations of Vancouver's urban boundary layer : validation and mixed-layer height estimation." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/1599.

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A mini-lidar system, Vaisala's CL31 ceilometer, was installed within a suburban area of Vancouver, BC, for the purpose of making continuous observations of the boundary layer over a period of 11 months. Initial validation of the ceilometer for use in boundary layer observations was undertaken. This involved the comparison of ceilometer data with eight months of ground-level particulate matter measurements, as well as with 16 vertical profiles of particulate matter and meteorological data. Once a variety of persistent noise structures within the data were accounted for, it was found that the ceilometer data showed good agreement with the particulate matter data, suggesting its usefulness for assessing air-quality throughout the bottom 1km of the atmosphere. Additionally, two algorithms were developed in order to estimate the height of the convective boundary layer, or the mixed-layer height, from the ceilometer data. One involved the fitting of an ideal-profile to the measured data, while the other involved the location of a minimum-gradient in the backscatter profile. The performance of these two techniques were assessed and compared, and it was found that the ideal-profile method was the more robust of the two. Finally, mixed-layer heights were estimated for fair weather, convectively active days. In order to isolate such conditions, an automatic flagging algorithm was developed. However, additional manual assessment was needed to avoided unsuitable conditions. Mixed-layer heights were estimated for 19 days over an 11 month period. the estimates presented here were found to agree with previous observations. Daily maximum mixed-layer heights ranged from 650m in July to 350m in December, indicating that the height of the convective boundary layer within Vancouver is significantly suppressed due to the city's coastal location.
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14

Lloyd, Matthew R. "Doppler LiDAR Measurements of Boundary Layer Heights over San Jose, California." Thesis, San Jose State University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10744231.

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There is a need for understanding boundary layer depth and climatology over the urban area of San Jose, California. In this paper, Doppler LiDAR data are observed from San Jose. The adopted methods of vertical velocity variance and skewness are used to determine the estimated height of the convective boundary layer and to analyze sources of turbulence. The use of these methods helped identify a few types of the boundary layer that are common in San Jose. Also examined in this paper is a brief climatology of the mean maximum convective boundary layer height in San Jose over the period of 2013–2015. Vertical velocity variance and skewness is applied to identify seasonal trends in the convective boundary layer height. The influence that the marine layer has on the boundary layer over San Jose is analyzed and a conduit for future work is set forth.

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15

Tourigny, Pierre. "Inclusion de la condensation dans un modèle de couche limite." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66104.

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16

Gobel, Teresa M. "Aircraft observations of the atmospheric boundary layer in the vicinity of the marginal ice zone under conditions of flow parallel to the ice edge." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA241072.

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Thesis (M.S. in Meteorology and Oceanography)--Naval Postgraduate School, September 1990.
Thesis Advisor(s): Shaw, W.J. Second Reader: Nuss, W.A. "September 1990." Description based on title screen as viewed on December 29, 2009. DTIC Identifier(s): Marine atmospheres, marginal ice zones, geostropic wind, atmospheric boundary layer, stratus clouds, cumulus clouds, stratocumulus clouds, wind velocity, temperature inversion, air ice interactions. Author(s) subject terms: Marginal ice zone. Includes bibliographical references (p. 45-46). Also available in print.
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17

Cross, Patrick S. "The California coastal jet : synoptic controls and topographically induced mesoscale structure /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Mar%5FCross.phd.pdf.

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18

Söderberg, Stefan. "Mesoscale dynamics and boundary-layer structure in topographically forced low-level jets." Doctoral thesis, Stockholm University, Department of Meteorology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-63.

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Two types of mesoscale wind-speed jet and their effects on boundary-layer structure were studied. The first is a coastal jet off the northern California coast, and the second is a katabatic jet over Vatnajökull, Iceland. Coastal regions are highly populated, and studies of coastal meteorology are of general interest for environmental protection, fishing industry, and for air and sea transportation. Not so many people live in direct contact with glaciers but properties of katabatic flows are important for understanding glacier response to climatic changes. Hence, the two jets can potentially influence a vast number of people.

Flow response to terrain forcing, transient behavior in time and space, and adherence to simplified theoretical models were examined. The turbulence structure in these stably stratified boundary layers was also investigated. Numerical modeling is the main tool in this thesis; observations are used primarily to ensure a realistic model behavior.

Simple shallow-water theory provides a useful framework for analyzing high-velocity flows along mountainous coastlines, but for an unexpected reason. Waves are trapped in the inversion by the curvature of the wind-speed profile, rather than by an infinite stability in the inversion separating two neutral layers, as assumed in the theory. In the absence of blocking terrain, observations of steady-state supercritical flows are not likely, due to the diurnal variation of flow criticality.

In many simplified models, non-local processes are neglected. In the flows studied here, we showed that this is not always a valid approximation. Discrepancies between simulated katabatic flow and that predicted by an analytical model are hypothesized to be due to non-local effects, such as surface inhomogeneity and slope geometry, neglected in the theory. On a different scale, a reason for variations in the shape of local similarity scaling functions between studies is suggested to be differences in non-local contributions to the velocity variance budgets.

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Mauritsen, Thorsten. "On the Arctic Boundary Layer : From Turbulence to Climate." Doctoral thesis, Stockholm : Department of Meteorology, Stockholm University, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-6585.

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20

Sullivan, Zachary S. "Karst Landscape Influence on the Planetary Boundary Layer Atmosphere." TopSCHOLAR®, 2016. http://digitalcommons.wku.edu/theses/1638.

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Karst landscapes cover approximately 20% of the ice-free land area worldwide. The soluble nature of the bedrock within a karst landscape allows for the formation of caverns, joints, fissures, sinkholes, and underground streams, which affect the hydrological behavior of the region. Currently, the Noah Land-Surface Model (Noah- LSM), coupled with the Weather Research and Forecasting (WRF) model, does not provide a representation of the physical behavior of a karst terrain. Previous research has attempted to model karst behavior through soil moisture and land cover/land use changes to determine the influence this unique landscape may have on atmospheric phenomenon. This highlights the need to study the potential influence that karst landscapes may have on model simulations. For this study, several factors were taken into account while studying karst and meteorology: the verification of a current operational forecasting model against observational data over five years (2007 to 2011), the formation of a karstlike soil type for use within an operational forecasting model, and model behavior once this karst-like soil type was added to the operational forecasting model. The verification of a currently operational forecasting model, the North American Mesoscale (NAM), indicated that, overall, the karst regions may exhibit an influence on local winds (greater error) and precipitation (frequency and forecasting). When developing a realistic karst-like soil proxy for use in the Noah-LSM, hydraulic conductivity values show a variation ranging from around 10-7 and 10-5 m s-1 for the karst bedrock within Tennessee and Kentucky. Sandy loam and clay soils were used, along with bedrock parameters, to determine an average soil parameter type for the epikarst bedrock located within this region. The model study demonstrated that the addition of karst highlighted the potential influence on precipitation distribution and energy fluxes, through RMSD and R2 values taken at a 95% confidence interval.
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Elge, Murat. "Langmuir circulations in a coastal environment during CBLAST." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Sept%5FElge.pdf.

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Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, Sept. 2004.
Thesis advisor(s): Timothy P. Stanton. Includes bibliographical references (p. 95-99). Also available online.
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Comstock, Kimberly K. "Mesoscale variability and drizzle in southeast Pacific stratocumulus /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/10013.

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Derley, Dennis T. "Remote sensing of the refractive environment above the marine stratocumulus-topped boundary layer." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2006. http://library.nps.navy.mil/uhtbin/hyperion/06Sep%5FDerley.pdf.

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Thesis (M.S. in Physical Oceanography and Meteorology)--Naval Postgraduate School, September 2006.
Thesis Advisor(s): Philip A. Durkee. "September 2006." Includes bibliographical references (p. 65). Also available in print.
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Baum, Bryan Alan. "The extension of rapid distortion theory to stratified shear flows." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/25971.

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Eleuterio, Daniel P. "Coastal stratocumulus topped boundary layers and the role of cloud-top entrainment." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Jun%5FEleuterio%5PhD.pdf.

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26

Eronn, Ingrid. "Effects of a Sea Breeze Circulation on Fluxes in the Marine Boundary Layer Over the Baltic Sea." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-392488.

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Two days in May 1997 has been studied. During one of the days a sea breeze circulation occured, and the two days were compared in search for effects from the sea breeze on the fluxes in the marine boundary layer. Measurements were made on a tower at the small island Östergarnsholm east of the island Gotland, and by an instrumented aircraft over the sea east and west of Gotland. The direction of the geostrophic wind were about northwest during the time period, but 17 m/s during May 3 and 7 m/s during May 4. The stratification was stable over the main part of the Baltic sea because of the large temperature differences between land and sea surfaces. But as the sea breeze developed and the wind direction turned to the southeast, the stratification at Östergarnsholm changed to near neutral. Both the wind speed and the fluxes decreased with distance from the Swedish mainland and the west coast of Gotland, and the fluxes were over all very small. The momentum flux showed no big difference between the days. Because of the decrease with the distance from the coast and the wind speed it was concluded that the stratification was of greater importance than the sea breeze circulation for the momentum fluxe. But the heat flux was affected by the sea breeze. Because of the sea breeze the stratification became neutral, and thus the heat flux very small. The presence of swell in the baltic sea was also studied. The correlation coefficient gave unexpected result during May 3, with no difference for swell and no swell conditions. The angle between the swell and the wind wave was about 90° during both days, and could not be the reason for the difference. During the May 3 the stratification was mostly stable, while it on May 4 was unstable. It is suggested that this could be a reason for the behaviour of ruw.
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Newton, D. Adam. "COAMPS modeled surface layer refractivity in the Roughness and Evaporation Duct experiment 2001." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Jun%5FNewton.pdf.

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Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, June 2003.
Thesis advisor(s): Kenneth Davidson, Douglas Miller. Includes bibliographical references (p. 59-60). Also available online.
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Svensson, Jacob. "Boundary Layer Parametrization in Numerical Weather Prediction Models." Licentiate thesis, Stockholms universitet, Meteorologiska institutionen (MISU), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-117134.

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Numerical weather prediction (NWP) and climate models have shown to have a challenge to correctly simulate stable boundary layers and diurnal cycles. This aim of this study is to evaluate, describe and give suggestions for improvements of the descriptions of stable boundary layers in operational NWP models. Two papers are included. Paper I focuses on the description of the surface and the interactions between the surface and the boundary layer in COAMPSR, a regional NWP model. The soil parametrization showed to be of great importance to the structure of the boundary layer. Moreover, it showed also that a low frequency of radiation calculations caused a bias in received solar energy at the surface. In paper II, the focus is on the formulation of the turbulent transport in stable boundary layers. There, an implementation of a diffusion parametrization based on the amount of turbulent kinetic energy (TKE) is tested in a single column model (SCM) version of the global NWP model Integrated Forecast System (IFS). The TKE parametrization turned out to behave similarly as the currently operational diffusion parametrization in convective regimes and neutral regimes, but showed to be less diffusive in weakly stable and stable conditions. The formulations of diffusion also turned out to be very dependent on the length scale formulation. If the turbulence and the gradients of wind temperature and wind are weak, the magnitude of turbulence can enter an oscillating mode. This oscillation can be avoided with the use of a lower limit of the length scale.
Det har visat sig att det är en stor utmaning för numeriska väderprognosmodeller (NWP-modeller) att simulera stabilt skiktade atmosfäriska gränsskikt och gränsskiktets dygnscykel på ett korrekt sätt. Syftet med denna studien är att utvärdera, beskriva och ge förslag på förbättringar av beskrivningen av gränsskiktet i NWP-modeller. Studien innehåller två artiklar. Den första fokuserar på beskrivningen av markytan och interaktionen mellan marken och gränsskiktet i den regionala NWP-modellen COAMPS R . Det visade sig att beskrivningen av markytan har en signifikant inverkan på gränsskiktets struktur. Det framkom också att strålningsberäkningarna endast görs en gång i timmen vilket bland annat orsakar en bias i inkommande solinstrålning vid markytan. Den andra artikeln fokuserar på beskrivningen av den turbulenta transporten i stabila skiktade gränsskikt. En implemenering av en diffusionsparametrisering som bygger på turbulent kinetisk energy (TKE) testas i en endimensionell version av NWP-modellen Integrated Forecast System (IFS), utvecklat vid European Center for Medium Range Weather Forecasts (ECMWF). Den TKE-baserade diffussionsparametriseringen är likvärdigt med den nuvaran de operationella parametriseringen i neutrala och konvektiva gränsskikt, menär mindre diffusivt i stabila gränsskikt. Diffusionens intensitet är beroende påden turbulenta längdskalan. Vidare kan turbulensen i TKE-formuleringen hamna i ett oscillerande läge om turbulensen är svag samtidigt som temperatur- och vindgradienten är kraftig. Denna oscillation kan förhindras om längdskalans minsta tillåtna värde begränsas.
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Mengesha, Yoseph Gebrekidan. "Atmospheric boundary-layer flow over topography data analysis and representations of topography /." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ39212.pdf.

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Liu, Chun-ho. "Numerical modelling of atmospheric boundary layer with application to air pollutant dispersion /." Hong Kong : University of Hong Kong, 1998. http://sunzi.lib.hku.hk/hkuto/record.jsp?B20158695.

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31

Ahn, Seungki. "Some unsteady features of turbulent boundary layers." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/53090.

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For steady free-stream, zero and favorable pressure gradient turbulent boundary layers, the unsteadiness in the form of turbulent fluetuations was investigated. Phase ensemble-averaged flow characteristics of a large amplitude periodic unsteady turbulent boundary layer was also investigated at a redueed frequency k = 0.61 based on the length of the eonverging and diverging test section with amplitude to mean velocity ratio of 0.8. ln steady flow cases, both zero and favorable pressure gradient flows show good two—dimensional flow characteristics and mean flow characteristics are compared with other researchers’ data. Measured power spectral data show good agreement with those of Klebanoff, Ueda and Hinze, Perry, Lim and Henbest for the zero pressure gradient flows and Jones and Launder for the favorable pressure gradient flow. The power spectral data measured in the turbulent wall region of the zero pressure gradient flow closely follow the model equation proposed by Perry, Lim and Henbest. Convective wave speed also show good agreement with those of Favre, Gaviglio and Dumas and Sternberg within the experimental uncertainties. ln the inner region of the boundary layer where y+ < 40, convective wave speed is higher than local mean velocity at all eddy scales as observed by Kline, Reynolds, Schraub and Runstadler. In the unsteady flow case, in the absence of flow reversal, the flow behaves in a quasi-steady manner and can be described by the steady flow structure as in the case of moderate amplitude flows. The Ludwieg·Tillmann skin friction equation and the Perry-Schofield universal velocity defect law hold at these phases. Except the laminariscent velocity profile observed during the acceleration phases, the large amplitude unsteady flow shows basically the same flow characteristics as the moderate amplitude flows.
Master of Science
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32

Hedley, Mark. "The effects of lateral boundary conditions on a two-dimensional cloud model /." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65503.

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Arduini, Gabriele. "Wintertime stable boundary-layer processes in Alpine valleys." Thesis, University of Hertfordshire, 2017. http://hdl.handle.net/2299/19706.

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Alpine valleys are rarely closed systems, implying that the atmospheric boundary layer of a particular valley section is influenced by the surrounding terrain and large-scale flows. A detailed characterisation and quantification of these effects is required in order to design appropriate parameterisation schemes for complex terrains. The focus of this work is to improve the understanding of the effects of surrounding terrain (plains, valleys or tributaries) on the heat and mass budgets of the stable boundary layer of a valley section, under dry and weak large-scale wind conditions. Numerical simulations using idealised and real frameworks are performed to meet this goal. Several idealised terrains (configurations) were considered: an infinitely long valley (i.e. two-dimensional), and upstream valleys opening either on a plain (valley-plain), on a wider valley (draining) or on a narrower valley (pooling). In three-dimensional valleys, two main regimes can be identified for all configurations: a transient regime, before the down-valley flow develops, followed by a quasi-steady regime, when the down-valley flow is fully developed. The presence of a downstream valley reduces the along-valley temperature difference, therefore leading to weaker down-valley flows. As a result, the duration of the transient regime increases compared to the respective valley-plain configuration. Its duration is longest for the pooling configuration. For strong pooling the along-valley temperature difference can reverse, forcing up-valley flows from the narrower towards the wider valley. In this regime, the average cooling rate at the valley-scale is found to be a maximum and its magnitude is dependent on the configuration considered. Therefore pooling and draining induce colder and deeper boundary layers than the respective valley-plain configurations. In the quasisteady regime the cooling rate is smaller than during the transient regime, and almost independent of the configuration considered. Indeed, as the pooling character is more pronounced, the warming contribution from advection to the heat budget decreases because of weaker down-valley flows, and so does the cooling contribution from the surface sensible heat flux. The mass budget of the valley boundary layer was found to be controlled by a balance between the convergence of downslope flows at the top of the boundary layer and the divergence of the down-valley flow along the valley axis, with negligible contributions of subsidence far from the valley sidewalls. The mass budget highlighted the importance of the return current above the down-valley flow, which may contribute significantly to the inflow of air at the top of the boundary layer. A case-study of a persistent cold-air pool event which occurred in February 2015 in the Arve River Valley during the intensive observation period 1 (IOP1) of the PASSY- 2015 field campaign, allowed us to quantify the effects of neighbouring valleys on the heat and mass budgets of a real valley atmosphere. The cold-air pool persisted as a result of warm air advection at the valley top, associated with the passage of an upper-level ridge over Europe. The contributions from each tributary valley to the mass and heat budgets of the valley atmosphere were found to vary from day to day within the persistent stage of the cold-air pool, depending on the large-scale flow. Tributary flows had significant impact on the height of the inversion layer and the strength of the cold-air pool, transporting a significant amount of mass within the valley atmosphere throughout the night. The strong stratification of the near-surface atmosphere prevented the tributary flows from penetrating down to the valley floor. The evolution of the large-scale flow during the episode had a profound impact on the near-surface circulation of the valley. The channelling of the large-scale flow at night, can lead to the decrease of the horizontal temperature difference driving the near-surface down-valley flow, favouring the stagnation of the air close to the ground.
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34

Zhou, Jingnan. "Numerical studies of stably stratified planetary boundary-layer flows over topography and their parameterization for large scale numerical model." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/mq27395.pdf.

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35

Vogel, Christoph Alexander. "An investigation of the role of flux divergence in the turbulent kinetic energy balance of the atmospheric surface layer." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/25789.

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36

Curry, Michelle. "An examination of lake breezes in southern Manitoba." Atmosphere-Ocean, 2015. http://hdl.handle.net/1993/31077.

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Lakes represent a major topographic feature in southern Manitoba, having a direct meteorological influence on a number of communities, including Winnipeg. Therefore, it is crucial that we have an understanding of the characteristics of lake breezes in the region and the influence that they can have on local weather. The Effects of Lake Breezes on Weather in Manitoba (ELBOW-MB) project in 2013 sought to fill in the gaps in our current knowledge of lake breezes in southern Manitoba. The primary research objectives of this thesis are to: (1) provide a radar-based climatology of lake breeze frequency and characteristics and, (2) to characterize the detailed thermodynamic and kinematic properties of lake breezes and lake-breeze fronts. The two results papers presented within this thesis represent the first detailed analysis of lake breezes in southern Manitoba and help to fill important gaps in our knowledge about the occurrence and characteristics of lake-breeze circulations.
February 2016
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37

Cardon, Sandra Jean. "Obtaining eddy fluxes for a non-homogeneous environment using wavelet cospectra." Laramie, Wyo. : University of Wyoming, 2007. http://proquest.umi.com/pqdweb?did=1320974421&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.

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38

McCaa, James Robert. "A new parameterization of marine stratocumulus and shallow cumulus clouds for climate models /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/10019.

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39

Dusek, Ulrike. "Characterization of marine boundary layer aerosol from north Atlantic and European sources : physical and chemical properties and climate forcing parameters /." Thesis, Connect to this title online; UW restricted, 2002. http://hdl.handle.net/1773/10065.

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40

Moore, Matthew J. "Evolution of boundary layer height in response to surface and mesoscale forcing." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Mar%5FMoore.pdf.

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41

Tastula, Esa-Matti. "Insights into the Challenges of Modeling the Atmospheric Boundary Layer." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5782.

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This work approaches the topic of modeling the atmospheric boundary layer in four research projects, which are summarized below. i) The diurnal cycles of near-surface meteorological parameters over Antarctic sea ice in six widely used atmospheric reanalyses were validated against observations from Ice Station Weddell. The station drifted from February through May 1992 and provided the most extensive set of meteorological observations ever collected in the Antarctic sea ice zone. For the radiative and turbulent surface fluxes, both the amplitude and shape of the diurnal cycles varied considerably among different reanalyses. Near-surface temperature, specific humidity, and wind speed in the reanalyses all featured small diurnal ranges, which, in most cases, fell within the uncertainties of the observed cycle. A skill score approach revealed the superiority of the ERA-Interim reanalysis in reproducing the observed diurnal cycles. An explanation for the shortcomings in the reanalyses is their failure to capture the diurnal cycle in cloud cover fraction, which leads to errors in other quantities as well. Apart from the diurnal cycles, NCEP-CFSR gave the best error statistics. ii) The accuracy of prediction of stable atmospheric boundary layers depends on the parameterization of the surface layer which is usually derived from the Monin-Obukhov similarity theory. In this study, several surface-layer models in the format of velocity and potential temperature Deacon numbers were compared to observations from CASES-99, Cardington, and Halley datasets. The comparisons were hindered by a large amount of scatter within and among datasets. Tests utilizing R2 demonstrated that the Quasi-Normal Scale Elimination (QNSE) theory exhibits the best overall performance. Further proof of this was provided by 1D simulations with the Weather Research and Forecasting (WRF) model. iii) The increasing number of physics parameterization schemes adopted in numerical weather forecasting models has resulted in a proliferation of inter-comparison studies in recent years. Many of these studies concentrated on determining which parameterization yields results closest to observations rather than analyzing the reasons underlying the differences. In this work, the performance of two 1.5-order boundary layer parameterizations was studied, the QNSE and Mellor-Yamada-Janjić (MYJ) schemes, in the Weather Research and Forecasting (WRF) model. The objectives were to isolate the effect of stability functions on the near-surface values and vertical profiles of virtual temperature, mixing ratio and wind speed. The results demonstrate that the QNSE stability functions yield better error statistics for 2-m virtual temperature but higher up the errors related to QNSE are slightly larger for virtual temperature and mixing ratio. A surprising finding is the sensitivity of the model results to the choice of the turbulent Prandtl number for neutral stratification (Prt0): in the Monin-Obukhov similarity function for heat, the choice of Prt0 is sometimes more important than the functional form of the similarity function itself. There is a stability-related dependence to this sensitivity: with increasing near-surface stability, the relative importance of the functional form increases. In near-neutral conditions, QNSE exhibits too strong vertical mixing attributed to the applied turbulent kinetic energy subroutine and the stability functions including the effect of Prt0. iv) In recent years, many eddy-diffusivity mass flux (EDMF) planetary boundary layer (PBL) parameterizations have been introduced. Yet, most validations are based on idealized setups and/or single column models. To address this gap, this study focused on the effect the mass flux part has on the performance in the QNSE-EDMF PBL scheme in the WRF model by comparing the results to observations from the CASES-97 field campaign. In addition, two refined versions, one introducing the parameterized clouds to the WRF radiation scheme, and the second adding a different entrainment formulation, were evaluated. The introduction of mass flux reduced errors in the average moisture profile but virtual temperature and wind speed profiles did not change as much. The turbulent flux profiles for modeled virtual potential temperature were little affected, with consistent reasonable agreement with observations, if one allows for biases in the observed data and modeled surface fluxes. However, the water vapor flux divergences from QNSE tend to be more negative than observed, while including the mass flux part tends to make the divergences more positive, the latter at least partially due to deeper model PBLs resulting from excessive model surface virtual temperature fluxes. Further, both virtual potential temperature and water vapor flux profiles display spurious spikes attributed to the way the non-local and local terms interact in the model. The influence of the mass flux schemes extends to 60 – 100-km scale circulation features, which were greatly modified by both the inclusion of mass flux and the new entrainment formulation. Adding mass flux based clouds to the radiation calculation improved the time and space averaged modeled incoming shortwave flux. The choice of the representation for entrainment/detrainment often affected the results to the same extent as adding mass flux did.
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42

Papageorgiou, I. G. "Mesoscale modelling of the atmospheric boundary layer including pollutant dispersion of a coastal area." Thesis, University of Reading, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356134.

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43

Miao, Qun. "Fine-scale vertical structure of clear-air echoes during the International H₂O Project as detected by an airborne Doppler radar." Laramie, Wyo. : University of Wyoming, 2006. http://proquest.umi.com/pqdweb?did=1296094731&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.

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44

Dasi, Lakshmi Prasad. "Statistical characteristics of turbulent chemical plumes." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/21256.

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45

Mathieu, Nathalie. "A study of atmospheric properties and their impact on the use of the nocturnal boundary layer budget technique for trace gas measurement /." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82291.

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While most micrometeorological measurement techniques are only suitable for windy conditions, the Nocturnal Boundary Layer Technique can be used to measure trace gas flux during calm, clear nights as the nighttime stability enables gas emitted at the ground to accumulate. The difference between two measurements over the whole depth of this layer is believed to integrate emissions from a large area representative of, in this study, an agricultural farm. A tethersonde and infrared gas analyzer attached to a blimp carrying a bag sampling system monitored atmospheric variables for each ascent during two summer field campaigns. A mini-SODAR was installed in the field to obtain the wind flowfield. Strong accumulation was observed under low level jets suggesting that this feature acts as a good lid for trace gases. An average background vertical motion different from zero seemed to have more influence on gas propagation than did intermittent turbulence. On at least one night, a density current created by the nearby St-Lawrence River was observed to influence measurements.
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46

Crofoot, Robert F. "Investigations of scalar transfer coefficients in fog during the Coupled Boundary Layers and Air Sea Transfer Experiment : a case study." Thesis, Monterey, California. Naval Postgraduate School, 2004. http://hdl.handle.net/10945/1202.

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The uncertainty in the determination of the momentum and scalar fluxes remains one of the main obstacles to accurate numerical forecasts in low to moderate wind conditions. For example, latent heat fluxes computed from data using direct covariance and bulk aerodynamic methods show that there is good agreement in unstable conditions when the latent heat flux values are generally positive. However, the agreement is relatively poor in stable conditions, particularly when the moisture flux is directed downward. If the direct covariance measurements are indeed accurate, then they clearly indicate that the bulk aerodynamic formula overestimate the downward moisture flux in stable conditions. As a result, comparisons of the Dalton number for unstable and stable conditions indicate a marked difference in value between the two stability regimes. Investigations done for this thesis used data taken primarily at the Air-Sea Interaction Tower (ASIT) during the Coupled Boundary Layers and Air-Sea Transfer (CBLAST) Experiment 2003 from the 20-27 August 2003. Other data from the shore based Martha's Vineyard Coastal Observatory (MVCO) and moored buoys in the vicinity of the ASIT were also incorporated. During this eight day period, the boundary layer was often characterized by light winds, a stably stratified surface layer and a swell dominated wave field. Additionally, the advection of warm moist air over cooler water resulted in fog formation and a downward flux of moisture on at least three occasions. Therefore, a primary objective of this thesis is to present a case study to investigate the cause of this shortcoming in the bulk formula under these conditions by examining the physical processes that are unique to these boundary layers. Particular attention will be paid to the behavior of the Dalton number in a stable marine atmospheric boundary layer under foggy conditions using insights derived from the study of fog formation and current flux parameterization methods.
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47

Cooper, Grant Alexander. "Variational retrieval of Eastern Pacific atmospheric boundary layer parameters using ATOVS with the COAMPSi mesoscale forecast system /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02sep%5FCooper%5FPhD.pdf.

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Thesis (Ph. D. in Meteorology)--Naval Postgraduate School, September 2002.
Dissertation co-advisors: Phillip A. Durkee, Nancy L. Baker. Includes bibliographical references (p. 235-242). Also available online.
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48

Nappo, Carmen Joseph. "A theoretical investigation of gravity-wave-generated stress and vorticity in the planetary boundary layer." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/25697.

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49

Parmhed, Oskar. "Near surface atmospheric flow over high latitude glaciers." Doctoral thesis, Stockholm University, Department of Meteorology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-197.

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In this thesis various descriptions of the near surface atmospheric flow over a high latitude glacier is used in an effort to increase our understanding of the basic flow dynamics there.

Through their contribution to sea-level change, mountain glaciers play a significant role in Earth’s climate system. Properties of the near surface atmospheric flow are important for understanding glacier response to climate change.

Here, the near surface atmospheric flow is studied from several perspectives including the effects of both rotation and slope. Rotation is an important aspect of most atmospheric flows and its significance for mesoscale flows have gained recognition over the last years. Similarly, the very stable boundary layer (VSBL) has lately gained interest. Within a VSBL over sloping terrain katabatic flow is known to be usual and persistent. For the present thesis a combination of numerical and simple analytical models as well as observations from the Vatnajökull glacier on Iceland have been used. The models have continuously been compared to available observations. Three different approaches have been used: linear wave modeling, analytic modeling of katabatic flow and of the Ekman layer, and numerical simulations of the katabatic flow using a state of the art mesoscale model. The analytic models for the katabatic flow and the Ekman layer used in this thesis both utilizes the WKB method to allow the eddy diffusivity to vary with height. This considerably improves the results of the models. Among other findings it is concluded that: a large part of the flow can be explained by linear theory, that good results can be obtained for surface energy flux using simple models, and that the very simple analytic models for the katabatic flow and the Ekman layer can perform adequately if the restraint of constant eddy diffusivity is relieved.

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50

Caldwell, Peter M. "Subtropical stratocumulus and its effect on climate /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/10054.

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