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1.
Measurements and modeling of air mass motion in the troposphere
Miha Živec, 2016, diplomsko delo

Opis: Throughout the history human race depended on weather, so one of the priorities for its survival was to understand weather patterns and to be able to forecast weather. With the development of powerful computers, atmospheric numerical methods and precision instruments for atmospheric monitoring, it is possible to predict weather with greater accuracy and for a longer period of time ahead. At the same time, we are able to gain improved understanding of physical processes that occur in the atmosphere and represent one of most important features in our world. This diploma thesis focuses on the lowest part of the atmosphere - troposphere only, as all weather occurs in the troposphere. Weather is a complete collection of momentary thermodynamic states in the atmosphere and is defined with thermodynamic variables and relations between them. The goal of this thesis is development and presentation of a new way to determine the direction and speed of air mass movement, based on the combination of passive and active remote sensing techniques. A lidar is being used to determine the range to an object, in our case a cloud, that can be used as a tracer in the air current. Simultaneously with lidar ranging of clouds that same clouds are being visually monitored in a series of optical photographs. Selecting and following the temporal evolution of distinct cloud features and their range allows us to calculate the speed of clouds. The performance of this method was tested on four cases in Feb. and Mar. 2016. Measurements were performed in Ajdovščina in different weather conditions. Along with remote sensing (infra-red lidar and optical cameras), ground measurements of wind at Ajdovščina were performed. Wind speeds and directions obtained from remote sensing were compared to atmospheric sounding data from Ljubljana and Udine at similar heights and performed within as small as possible time window. In all four cases remote sensing results for wind speeds and directions agree relatively well with atmospheric sounding. Deviations are expected to be primarily due to spatial and temporal mismatch between sounding and remote sensing measurements. Another source of uncertainties are the limitations of the present remote sensing method in the determination of the actual direction of the wind, however, theses limitations could be eliminated in the future by using an all-sky camera and vertical lidar configuration.
Najdeno v: ključnih besedah
Povzetek najdenega: ...of physical processes that occur in the atmosphere and represent one of most important features...
Ključne besede: remote sensing, wind, atmosphere
Objavljeno: 13.10.2016; Ogledov: 3008; Prenosov: 67
.pdf Polno besedilo (9,48 MB)

2.
Tracer concentration profiles measured in central London as part of the REPARTEE campaign
Damien Martin, K Fredrik Petersson, Iain R White, Stephen H Henshaw, Graham Nickless, Amy Lovelock, Janet F Barlow, Tyrone Dunbar, Curtis R Wood, Dudley E. Shallcross, 2011, izvirni znanstveni članek

Opis: There have been relatively few tracer experiments carried out that have looked at vertical plume spread in urban areas. In this paper we present results from two tracer (cyclic perfluorocarbon) experiments carried out in 2006 and 2007 in central London centred on the BT Tower as part of the REPARTEE (Regent's Park and Tower Environmental Experiment) campaign. The height of the tower gives a unique opportunity to study vertical dispersion profiles and transport times in central London. Vertical gradients are contrasted with the relevant Pasquill stability classes. Estimation of lateral advection and vertical mixing times are made and compared with previous measurements. Data are then compared with a simple operational dispersion model and contrasted with data taken in central London as part of the DAPPLE campaign. This correlates dosage with non-dimensionalised distance from source. Such analyses illustrate the feasibility of the use of these empirical correlations over these prescribed distances in central London.
Najdeno v: ključnih besedah
Povzetek najdenega: ...advection, concentration (composition), dispersion, tracer, urban atmosphere, vertical mixing, vertical profile...
Ključne besede: advection, concentration (composition), dispersion, tracer, urban atmosphere, vertical mixing, vertical profile
Objavljeno: 18.07.2019; Ogledov: 131; Prenosov: 0
.pdf Polno besedilo (1,49 MB)

3.
Atmospheric chemistry and physics in the atmosphere of a developed megacity (London): An overview of the REPARTEE experiment and its conclusions
Gavin J Phillips, Carole Helfter, Chiara F Di Marco, Eiko Nemitz, Fay Davies, Janet F Barlow, Tyrone Dunbar, Iain R White, Dudley E Shallcross, Stephen J Henshaw, K Fredrik Peterson, Brian Davison, Damien Martin, Ben Langford, C Nicholas Hewitt, Stephen M Ball, Justin M Langridge, A K Benton, Roderick L Jones, Paul I Williams, John Whitehead, Martin W Gallagher, Claire Martin, James R Dorsey, Hugh Coe, James D Allan, William J Bloss, Alistair J Thorpe, David C S Beddows, Manuel DallOsto, Roy M Harrison, Steven Smith, 2012, pregledni znanstveni članek

Opis: The Regents Park and Tower Environmental Experiment (REPARTEE) comprised two campaigns in London in October 2006 and October/November 2007. The experiment design involved measurements at a heavily trafficked roadside site, two urban background sites and an elevated site at 160-190 m above ground on the BT Tower, supplemented in the second campaign by Doppler lidar measurements of atmospheric vertical structure. A wide range of measurements of airborne particle physical metrics and chemical composition were made as well as measurements of a considerable range of gas phase species and the fluxes of both particulate and gas phase substances. Significant findings include (a) demonstration of the evaporation of traffic-generated nanoparticles during both horizontal and vertical atmospheric transport; (b) generation of a large base of information on the fluxes of nanoparticles, accumulation mode particles and specific chemical components of the aerosol and a range of gas phase species, as well as the elucidation of key processes and comparison with emissions inventories; (c) quantification of vertical gradients in selected aerosol and trace gas species which has demonstrated the important role of regional transport in influencing concentrations of sulphate, nitrate and secondary organic compounds within the atmosphere of London; (d) generation of new data on the atmospheric structure and turbulence above London, including the estimation of mixed layer depths; (e) provision of new data on trace gas dispersion in the urban atmosphere through the release of purposeful tracers; (f) the determination of spatial differences in aerosol particle size distributions and their interpretation in terms of sources and physico-chemical transformations; (g) studies of the nocturnal oxidation of nitrogen oxides and of the diurnal behaviour of nitrate aerosol in the urban atmosphere, and (h) new information on the chemical composition and source apportionment of particulate matter size fractions in the atmosphere of London derived both from bulk chemical analysis and aerosol mass spectrometry with two instrument types.
Najdeno v: ključnih besedah
Ključne besede: megacity, trace gas, urban atmosphere, atmospheric transport, chemical composition, aerosol
Objavljeno: 18.07.2019; Ogledov: 149; Prenosov: 0
.pdf Polno besedilo (4,66 MB)

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