Atmospheric water vapor is a potent greenhouse gas, and its variations in the upper troposphere and lower stratosphere (UTLS) have important climate impacts. The water vapor budget of tropical cyclones (TCs) and their impact on the UTLS remain understudied. This paper describes high-resolution simulations of TC Ingrid during September 2013 using the Weather Research and Forecasting (WRF) model to calculate the water vapor budget. Using Ingrid as an example provides a better understanding of water vapor transport into the UTLS by TCs, helping to answer a question posed during NASA’s Studies of Emissions and Atmospheric Composition, Clouds, and Climate Coupling through Regional Surveys (SEAC4RS), specifically whether water vapor transport in TCs hydrates or dehydrates the UTLS. Our WRF simulations of TC Ingrid closely correspond to the National Hurricane Center’s Best Track data. We also evaluate model results of the water vapor budget with in situ airborne data of Ingrid collected during the SEAC4RS mission. Satellite imagery also is used to validate the simulated structure of Ingrid. We show spatial and temporal changes of UTLS water vapor throughout Ingrid's lifecycle to determine whether and how TCs hydrate or dehydrate the UTLS. Results show that TCs do transport large quantities of water vapor into the UTLS, and overshooting deep convection is an especially potent transport method. The paper sheds light on mechanisms that inject water vapor into the UTLS and on the widespread horizontal and vertical transports of water vapor within TCs. / A Thesis submitted to the Department of Earth, Ocean, and Atmospheric Science in partial fulfillment of the Master of Science. / Fall Semester 2016. / November 22, 2016. / flux, lower stratosphere, transport, tropical cyclone, upper troposphere, water vapor / Includes bibliographical references. / Henry Fuelberg, Professor Directing Thesis; Robert Hart, Committee Member; Vasu Misra, Committee Member; Christopher Holmes, Committee Member.

The Arctic Summer Cloud Ocean Study expedition took place during the autumn of 2008 and brought back water and air samples. One theory was that marine particles were shot into the atmosphere by bubble bursting and, while in the atmosphere, acted as cloud condensation nuclei. Particles collected from the subsurface water, surface microlayer and just above the surface had their topography and morphology analyzed using a scanning electron microscope. Due to a lack of EDS analysis it's impossible to say for sure if the particles found were the same found in previous studies, just that it is highly likely that they are. No evidence against the marine particles being able to act as cloud condensation nuclei was found but the data gathered was not sufficient to strengthen the theory either. The scanning electron microscope was also used in a pedagogical study, analyzing how operators with different knowledge and prior experience interact with the microscope's images. These results as well as knowledge gained from literature studies were used to improve a high school experiment regarding centripetal acceleration. The main issue with the experiment was that what the students learned performing the experiment was not the same as the theoretical models the teachers wished the students to learn. The reason for this was because the experimental equipment lacked the centripetal model's external representations such as force arrows. If a simulator would be incorporated into the lab centripetal acceleration representations could be visualized and a clearer connection between experiment and theory could be made.

Wind atlases are interactive databases used extensively for preliminary wind resource assessment aimed at optimal wind power development. The selection and processing of wind atlas data are important and will determine the quality of the subsequent WRA (Wind Resource Assessment) phases. This study aims to compare, process, and interpret different wind atlases in determining effective wind resource analysis for 14 different sites in Sweden. The wind atlas data is accessed, parsed, and compared using multiple methodologies to ensure a fair comparison. Several variables like wind speed, wind direction, temperature, production values, etc. are analysed and compared amongst the wind atlas data. The corrected versions of the data are drawn out to conclude and determine how well those databases represent the realistic conditions in a forested site. The data is also compared and validated with measurement data. The results indicate several layers of insights into the wind resource regime. The preliminary results from 14 sites show that New European Wind Atlas (NEWA) and Global Wind Atlas (GWA) agreed sufficiently on the subject of the wind conditions for most of the sites. Methodologies like downscaling and long-term correction introduced to the wind atlas data provided more insights and proved that the database could expand and include more complex wind conditions in the coming years. Furthermore, the comparison and analysis of wind atlas data along with measurement data revealed that NEWA aligned the most to the actual wind conditions for a site. Several uncertainties are considered but more validation and thorough insights in the future could determine and give more affirmations to the idea put forward. Further studies could be conducted along with the inclusion of additional layers, variables, and databases to the wind atlases.

Mätningar av gränsskikt som utförts i Marsta (MAO) under tidsperioden 1 juli 1994 till 28 februari 1995 har analyserats. Mätningarna, som genomfördes på en 30 meter hög mast, omfattar bland annat vindhastighet, vindriktning och temperatur på 6 nivåer. Långvågig in- och utstrålning uppmättes på en höjd, vilket även gällde turbulenta fluktuationer av vindens 3 komponenter och temperatur. Den här redovisade undersökningen inriktades på studier av stabila gränsskikt. Dels studerades turbulensen samt hur temperaturavtagandet vid bildningen av ett stabilt gränsskikt varierar med tiden. Även specialfallet, när ett neutralt skikt bildas vid markytan i det stabila gränsskiktet mitt i natten, studerades. För undersökning av turbulensen har jämförelser mellan dessa mätdata och andra undersökningars mätdata genomförts. Jämförelsen har gjorts med hjälp av Monin—Obukhovs similaritetsteori vilket innebär att man studerar hur de dimensionslösa standardavvikelsern för u, v, w och T och den dimensionslösa temperaturgradienten beror av z/L. Resultaten visade att överensstämmelsen mellan denna och andra undersökningar var relativt god. Genom numeriska beräkningar har man tidigare funnit att temperaturen nära marken minskar med roten ur tiden de första 3-4 timmarna, då skiktningen blir stabil. Detta gäller vid konstant långvågsutstrålning. I den här undersökningen uppgick motsvarande tidsperiod till 45 minuter. En ekvation som beskriver hur det neutrala skiktets höjd växer har härletts. Denna ekvations giltighet har även testats. Resultatet var inte entydigt.

Measurements collected at Cabauw, the Netherlands, during the period November 1996 to May 1997, have been evaluated. The study was focused on the calculation of turbulence characteristics and profiles of wind speed and temperature under stable and near neutral conditions in the atmospheric surface-layer. Results from a 1-dimensional second-order closure model was compared with the outcome from the present observational data. The Monin-Obukhov similarity was applied for calculating the non-dimensional wind (Φm) and temperature gradients (Φh), the obtained result are: Φm = 0.9 + 4.4z/L and Φh = 0.9 + 3.6z/L. We suggest to replace the length scale kz, in the length scale of the definition of the Φ-functions, with the integral length scale, Λw, since Λw is more related to the length scale of the most energetic turbulent motions. On basis of the measurement campaigns performed, it was not possible to verify unique functions for these non-dimensional profiles, and therefore it is suggested that another length scale besides kz must be of importance. Furthermore, the balance between shear production, viscous dissipation and the buoyancy in the turbulent kinetic energy budget were investigated. The values of the non-dimensional standard deviations of horizontal and vertical velocities are constant with regard to stability and in good agreement with figures reported in the literature. By using a 1-dimensional second-order closure model it has not been possible to describe the turbulence characteristics of the stable atmospheric surface-layer. Three different combinations of constants are shown in this report, and they indicate problems that occur when comparing closure model results with experimental data from a stable stratified atmosphere.

This thesis will examine the local effects of land cover on icing forecasts. In Paper I, a single column model was used to test the sensitivity of icing forecasts to land cover fraction. Here, the ice accretion forecast was found to be highly sensitive to the wind magnitude response to the surface roughness. Diabatic effects related to the surface albedo played a secondary role, significant in cases with strong solar irradiance. Paper II examined the impact of 2-dimensional patterns of land cover heterogeneity on the effective surface roughness and blending height using large eddy simulation over a diurnal cycle of solar irradiance. The blending height--or the elevation at which the atmospheric response to the underlying land cover becomes horizontally homogeneous--has been proposed as a guide for coupling numerical weather models to surface parameterizations. In stable conditions, when the atmospheric boundary layer height was shallow, the blending height over surfaces with large heterogeneity length scale was found to be much lower than that of analytical models from previous studies. A new formula for a dynamic blending height was proposed taking this effect into account. The effective surface roughness was found to decrease with increasing land cover heterogeneity. The wind power response from an idealized wind turbine with 80-meter hub height to the effective surface roughness was shown, with a positive response in wind power with increasing land cover heterogeneity. The wind power response was smaller and less systematic with wind turbines extending above the blending height, further highlighting the utility of an accurate formulation for this variable. / I den här avhandligen undersöks de lokala effekterna av landtäcke på isbildningsprognoser. I artikel I användes en enkolumns-modell för att testa känsligheten hos isbildningsprognoser för olika andelar landtäcke. Här visade sig isbildningsprognosen vara mycket känslig för ytans påverkan på vindstyrkan. Diabatiska effekter relaterade till ytalbedo spelade en sekundär roll, speciellt i fall med stark solinstrålning. Artikel II undersökte hur  tvådimensionella mönster i landtäckets heterogenitet påverkade den effektiva ytjämnheten och blandningshöjden med hjälp av simuleringar av en stor virvel under en dygnscykel av solinstrålning. Blandningshöjden - eller den höjd vid vilken atmosfärens respons på det underliggande marktäcket blir horisontellt homogent - har föreslagits fungera som  guide för  hur man kan koppla numeriska vädermodeller till ytparameteriseringar. Under stabila förhållanden, när den atmosfäriska gränsskiktshöjden var låg, visade sig blandningshöjden över ytor med stor heterogenitetslängdskala vara mycket lägre än den från analytiska modeller från tidigare studier. En ny formel för att beräkna dynamisk blandningshöjd föreslogs med hänsyn till denna effekt. Den effektiva ytjämnheten visade sig minska med ökande heterogenitet i landtäcket. Responsen med avseende på den effektiva ytjämnheten visades för en ideal vindturbin med 80 meters navhöjd , med en ökning i vindkraftsproduktion med ökande heterogenitet i landtäcket. Påverkan på produktionen var både mindre i allmänhet och även mindre systematisk för vindkraftverk som sträckte sig över blandningshöjden, vilket ytterligare understryker behovet av en exakt formulering av denna variabel.

To understand and model the energetics of the Sun-Earth connection, measurements of specific atmospheric molecules are beneficial. The objective is to formulate an algorithm to derive temporally varying atmospheric water vapor concentrations as functions of altitude, latitude, and longitude from solar irradiance absorption measurements. The Visidyne SAM (Sun and Aureole Measurement) instrument, which studies the size and distribution of cloud particles, was used to obtain the experimental data. By introducing a spectrometer to the SAM instrument, column water vapor is produced as part of the data product. A new model optimized algorithm is developed and tested versus existing algorithms. Through a least-squares analysis, the new algorithm showed an improvement of a factor of 23 over the industry standard. A test was also conducted to determine which water absorption bandpass produces the smallest error. Through these tests a model optimized algorithm has been produced.

The objective of this research is to quantify the LAMP’s performance when forecasting for IFR conditions at specific major airports for forecast hours one, three, six, and twelve, and further determine how the LAMP performs seasonally at those specific airports and forecast hours. Two by two contingency tables were used to calculate the Probability of Detection (POD), False Alarm Ratio (FAR), Critical Success Index (CSI), Heidke Skill Score (HSS), and Bias score. The results show that the LAMP performs relatively better in the cool season compared to the warm season consistently at each chosen airport, and that the LAMP performs worse when forecasting for West Coast airports relative to inland airports.

No description available.

<p>The health impacts of urban air pollution are a growing concern in our rapidly urbanizing world. Urban air pollutants show high intra-urban spatial variability linked to urban land use and land cover (LULC). This correlation of air pollutants with LULC is widely recognized; LULC data is an integral input into a wide range of models, especially land use regression models developed by epidemiologists to study the impact of air pollution on human health. Given the demonstrated links between LULC and urban air pollution, and between urban air pollution and health, an interesting question arises: what is the potential of LULC modifications to mitigate the health impacts of urban air pollution? </p><p> In this dissertation we assess the potential of LULC modifications to mitigate the health impacts of NO₂, a respiratory irritant and strong marker for combustion-related air pollution, in the Portland-Vancouver metropolitan area in northwestern USA. We begin by measuring summer and winter NO₂ in the area using a spatially dense network of passive NO₂ samplers. We next develop an annual average model for NO₂ based on the observational data, using random forest&mdash;for the first time in the realm of urban air pollution&mdash;to disentangle the effects of highly correlated LULC variables on ambient NO₂ concentrations. We apply this random forest (LURF) model to a 200m spatial grid covering the study area, and use this 200m LURF model to quantify the effect of different urban land use categories on ambient concentrations of NO₂. Using the changes in ambient NO₂ concentrations resulting from land use modifications as input to BenMAP (a health benefits assessment tool form the US EPA), we assess the NO₂-related health impact associated with each land use category and its modifications. We demonstrate how the LURF model can be used to assess the respiratory health benefits of competing land use modifications, including city-wide and local-scale mitigation strategies based on modifying tree canopy and vehicle miles traveled (VMT). </p><p> Planting trees is a common land cover modification strategy undertaken by cities to reduce air pollution. Statistical models such as LUR and LURF demonstrate a correlation between tree cover and reduced air pollution, but they cannot demonstrate causation. Hence, we run the atmospheric chemistry and transport model CMAQ to examine to what extent the dry deposition mechanism can explain the reduction of NO₂ which statistical models associate with tree canopy. </p><p> Results from our research indicate that even though the Portland-Vancouver area is in compliance with the US EPA NO₂ standards, ambient concentrations of NO₂ still create an annual health burden of at least $40 million USD. Our model suggests that NO₂ associated with high intensity development and VMT may be creating an annual health burden of $7 million and $3.3 million USD respectively. Existing tree canopy, on the other hand, is associated with an annual health benefit of $1.4 million USD. LULC modifications can mitigate some fraction of this health burden. A 2% increase in tree canopy across the study area may reduce incidence rates of asthma exacerbation by as much as 7%. We also find that increasing tree canopy is a more effective strategy than reducing VMT in terms of mitigating the health burden of NO₂. </p><p> CMAQ indicates that the amount of NO₂ removed by dry deposition is an order of magnitude smaller than that predicted by our statistical model. About one-third of the difference can be explained by the lower NO₂ values predicted by CMAQ, and one-third may be attributable to parameterization of stomatal uptake. </p>