Dissertations / Theses: 'Solar radiation; Atmospheric ozone'

1

Ball, Stephen M. "Studies of laser photolysis." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294334.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Nascimento, Cristina Rodrigues. "Correção atmosferica de imagens do sensor AVHRR/NOAA utilizando produtos atmosfericos do sensor MODIS/TERRA." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257080.

Full text

Abstract:

Orientador: Jurandir Zullo Junior
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola
Made available in DSpace on 2018-08-08T10:45:00Z (GMT). No. of bitstreams: 1 Nascimento_CristinaRodrigues_M.pdf: 15175487 bytes, checksum: d9905da2c3f9b6c5fa573693ce9e61a0 (MD5) Previous issue date: 2006
Resumo: O sensoriamento remoto nas regiões espectrais do visível e do infravermelho próximo constitui uma das ferramentas mais importantes para o entendimento da biosfera e de suas dinâmicas. Entretanto, estas duas regiões são afetadas pelos efeitos atmosféricos tais como, o espalhamento e a absorção,ocasionados por sua vez pelos aerossóis e gases atmosféricos. Na tentativa de obter o fator de reflectância bi-direcional da superfície terrestre, nos canais 1 e 2 do sensor AVHRR, foi realizada a correção atmosférica, baseada na entrada de dados, tais como espessura óptica dos aerossóis, coluna total de vapor d?água e carga total de ozônio, respectivamente fornecidos pelo sensor MODIS. O intuito da utilização deste sensor está diretamente relacionado à obtenção das informações, necessários para a correção atmosférica, considerando-se a variabilidade dos parâmetros no tempo e no espaço. Para tanto foi utilizado o aplicativo SCORADIS, fundamentado no modelo de transferência radiativa 5S, então adaptado, para possibilitar a correção atmosférica de toda a imagem do AVHRR a partir da entrada das imagens correspondentes aos planos atmosféricos, através da utilização de quatro metodologias distintas de correção atmosférica. As análises realizadas indicaram que as correções realizadas a partir dos dados atmosféricos do sensor MODIS apresentaram resultados coerentes com o esperado após a eliminação dos efeitos de espalhamento e de absorção atmosférica, nos canais 1 e 2 do NOAA-17, nas duas datas consideradas (14/07/2004 e 30/08/2005). Para o NDVI, a diferença percentual entre as imagens com e sem correção chegaram a ser de, aproximadamente, 60%, o que ressalta a importância da correção atmosférica destes canais, principalmente no acompanhamento da vegetação a partir de imagens multitemporais. Não se observou diferença significativa entre as metodologias utilizadas para a entrada dos dados atmosféricos no sistema de correção atmosférica, devido, possivelmente, à magnitude dos valores utilizados e à áreateste escolhida. Os produtos obtidos a partir das imagens do MODIS mostraram potencial para utilização na estimativa dos principais parâmetros atmosféricos necessários para a correção atmosférica (como a espessura óptica dos aerossóis e conteúdo de vapor d'água e ozônio) e que são de grande dificuldade para obtenção em campo
Abstract: Remote sensing in the spectral regions of visible and infrared is one of the most important techniques used for studying the biosphere. However these two spectral regions are affected by atmospheric effects as scattering and absorption, caused by aerosols and atmospheric gases. In the attempt to obtain the real reflectance of ground surface, in channels 1 and 2 of AVHRR sensor, was performed the atmospheric correction of two NOAA images acquired on July/14/2004 and August/30/2005, based on atmospheric data supplied by the MODIS sensor, considering the spatial and temporal variability of these parameters. The system SCORADIS, based on the radiative transfer model called 5S, was adapted to read images having values of aerosols optical thickness, water vapor content and ozone contents corresponding spatially to each pixel of a AVHRR/NOAA image. Four distinct methodologies were used to define the images of atmospheric parameters. Coherent results were obtained using atmospheric data from MODIS, indicating that the scattering and absorption effects were correctly eliminated from the NOAA images in the two dates considered. The difference between the NDVI calculated with corrected and noncorrected images was up to 60%, showing the importance of using corrected images in applications based on multitemporal images. There was not observed significant difference among the four methodologies applied to define the atmospheric data used in the atmospheric correction system due, maybe, to the magnitude of the values and to the atmospheric conditions of test-area. The atmospheric products from MODIS can be used to defining the input data (like aerosol optical thickness, water vapor contents and ozone contents) for the atmospheric correction systems of AVHRR/NOAA images
Mestrado
Planejamento e Desenvolvimento Rural Sustentável
Mestre em Engenharia Agrícola

APA, Harvard, Vancouver, ISO, and other styles

3

Ho, Wing-kwok. "Solar ultraviolet radiation : monitoring, dosimetry and protection /." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21583791.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Várnai, Tamás. "Reflection of solar radiation by inhomogeneous clouds." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40459.

Full text

Abstract:

The goal of this study is to improve knowledge about how cloud inhomogeneities affect the reflection of solar radiation. In particular, it addresses two main questions: what the processes through which inhomogeneities influence solar reflection are, and how this influence can be taken into account in albedo retrievals based on future satellite measurements.
The first question is important, since present methods give numerical results only about the overall radiative effect of cloud inhomogeneities, but cannot determine the degree to which various mechanisms are responsible for this overall effect. This study establishes a theoretical framework which defines and evaluates the various processes through which cloud inhomogeneities influence solar radiation. This framework is then used to examine quantitatively the inhomogeneity effects that occur in irregular cloud fields. Among other insights, it is shown and explained that identical variations in cloud optical thickness can cause much stronger inhomogeneity effects if they are due to variations in geometrical cloud thickness, and not in volume extinction coefficient (as assumed in previous studies of irregular cloud fields). The differences in albedo can exceed 0.05, and the relative differences in reflectance toward the zenith can be greater than 25% for overhead sun, and 50% for oblique sun. Also, a possible explanation is given for a phenomenon observed in previous studies: that cloud reflectivity toward the zenith increases with decreasing solar elevation.
This study also develops an albedo retrieval algorithm that considers radiative inhomogeneity effects. The algorithm takes advantage of the unique multi-view capability of the Multi-angle Imaging SpectroRadiometer (MISR) placed on the Earth Observing System-AM satellite (to be launched in 1998). This instrument will offer new possibilities for albedo retrievals since, unlike present instruments, it will measure the radiation reflected in not only one, but nine directions. The potential accuracy of the algorithm is analyzed for a dataset obtained by using a Monte Carlo model to simulate radiative transfer through a large number of irregular cloud fields. The results indicate that using multi-view measurements can improve the accuracy of satellite-based albedo retrievals by a factor of three or more.

APA, Harvard, Vancouver, ISO, and other styles

5

Yin, Bangsheng. "Solar radiation measurements and their applications in climate research." Thesis, State University of New York at Albany, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3595873.

Full text

Abstract:

Aerosols and clouds play important roles in the climate system through their radiative effects and their vital link in the hydrological cycle. Accurate measurements of aerosol and cloud optical and microphysical properties are crucial for the study of climate and climate change. This study develops/improves retrieval algorithms for aerosol single scattering albedo (SSA) and low liquid water path (LWP) cloud optical properties, evaluates a new spectrometer, and applies long-term measurements to establish climatology of aerosol and cloud optical properties. The following results were obtained.

(1) The ratio of diffuse horizontal and direct normal fluxes measured from Multifilter Rotating Shadowband Radiometer (MFRSR) has been used to derive the aerosol SSA. Various issues have impacts on the accuracy of SSA retrieval, from measurements (e.g., calibration accuracy, cosine respond correction, and forward scattering correction) to input parameters and assumptions (e.g., asymmetry factor, Rayleigh scattering optical depth, and surface albedo). This study carefully analyzed these issues and extensively assessed their impacts on the retrieval accuracy. Furthermore, the retrievals of aerosol SSA from MFRSR are compared with independent measurements from co-located instruments.

(2) The Thin-Cloud Rotating Shadowband Radiometer (TCRSR) has been used to derive simultaneously the cloud optical depth (COD) and cloud drop effective radius (DER), subsequently inferring the cloud liquid-water path (LWP). The evaluation of the TCRSR indicates that the error of radiometric calibration has limited impact on the cloud DER retrievals. However, the retrieval accuracy of cloud DER is sensitive to the uncertainties of background setting (e.g., aerosol loading and the existence of ice cloud) and the measured solar aureole shape.

(3) A new high resolution oxygen A-band spectrometer (HABS) has been developed, which has the ability to measure both direct-beam and zenith diffuse solar radiation with polarization capability. The HABS exhibits excellent performance: stable spectral response ratio, high SNR, high spectrum resolution (0.16 nm), and high Out-of-Band Rejection (10^-5). The HABS measured spectra and polarization spectra are basically consistent with the related simulated spectra. The main difference between them occurs at or near the strong oxygen absorption line centers. Furthermore, our study demonstrates that it is a good method to derive the degree of polarization-oxygen absorption optical depth (DOP-k) relationship through a polynomial fitting in the DOP-k space.

(4) The long-term MFRSR measurements at Darwin (Australia), Nauru (Nauru), and Manus (Papua New Guinea) sites have been processed to develop the climatology of aerosols and clouds in the Tropical Warm Pool (TWP) region at the interannual, seasonal, and diurnal temporal scales. Due to the association of these three sites with large-scale circulation patterns, aerosol and cloud properties exhibit distinctive characteristics. The cloud optical depth (COD) and cloud fraction (CF) exhibit apparent increasing trends from 1998 to 2007 and decreasing trends after 2007. The monthly anomaly values, to some extent, are bifurcately correlated with SOI, depending on the phase of ENSO. At the two oceanic sites of Manus and Nauru, aerosols, clouds, and precipitation are modulated by the meteorological changes associated with MJO events.

(5) The long-term measurements at Barrow and Atqasuk sites also have been processed to develop the climatology of aerosol and cloud properties in the North Slope of Alaska (NSA) region at interannual, seasonal, and diurnal temporal scales. Due to Arctic climate warming, at these two sites, the snow melting day arrives earlier and the non-snow-cover duration increases. Aerosol optical depth (AOD) increased during the periods of 2001-2003 and 2005-2009, and decreased during 2003-2005. The LWP, COD, and CF exhibit apparently decreasing trends from 2002 to 2007 and increased significantly after 2008. (Abstract shortened by UMI.)

APA, Harvard, Vancouver, ISO, and other styles

6

Koutoulaki, Aikaterini. "Study of ozone non-thermal IR emission using ISAMS observations." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298344.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Hudson, Stephen R. "Solar radiation processes on the East Antarctic Plateau : interaction of clouds, snow, and atmospheric gases /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/10066.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Albar, Ossama Fadhul. "The spectral distribution of solar ultraviolet radiation at the ground." Thesis, University of Nottingham, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303128.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Bednarz, Ewa Monika. "Chemistry-climate modelling studies of decadal and interdecadal variability in stratospheric ozone and climate : the 11-year solar cycle and future ozone recovery." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/274359.

Full text

Abstract:

The Earth’s atmosphere constitutes a complex system subject to a large number of forcings of both natural and anthropogenic origin; these influence its evolution on a range of timescales. This thesis makes use of the UMUKCA global chemistry-climate model to explore several aspects relating to the atmospheric response to the 11-year solar cycle forcing and future stratospheric ozone recovery. Firstly, following recent improvements in the model, the atmospheric response to the solar cycle forcing simulated in UMUKCA is discussed. It is shown that while some features show a broad resemblance to observations/reanalysis, there are clear differences with regard to other features; the latter could result from model deficiencies and/or uncertainties in the observed response. The role of analysis method and of interannual variability is also addressed. Secondly, the solar cycle response is separated into the individual contributions from direct radiative heating and from ozone production using a set of sensitivity experiments. It is shown that while the tropical yearly mean responses to the two components are generally linearly additive, this is not necessarily the case in the high latitudes. It is suggested that solar-induced ozone changes could be important for modulating the Southern Hemisphere dynamical response. Thirdly, the role of the representation of the solar ozone response is studied. It is shown that the choice of the solar ozone response prescribed in the radiation scheme in non-interactive ozone experiments has a substantial impact on the simulated temperature response to the solar cycle forcing. The Northern Hemisphere dynamical responses are found to be generally similar within the uncertainty. A comparison with an interactive ozone case is also discussed. Lastly, future ozone recovery is investigated using a seven-member ensemble of 1960- 2099/1980-2080 integrations. The long-term evolution of ozone in different regions is found to be generally consistent with previous modelling studies. The long-term trends and variability in springtime Arctic ozone and its chemical, radiative and dynamical drivers are assessed. It is shown that Arctic ozone increases in the future, consistent with future reduction in stratospheric chlorine, stratospheric cooling and strengthening large-scale circulation. Yet, the large interannual variability is found to continue and to facilitate episodic ozone reductions, with halogen chemistry becoming a smaller but non-negligible driver of future springtime Arctic ozone variability for many decades.

APA, Harvard, Vancouver, ISO, and other styles

10

Ho, Wing-kwok, and 何永國. "Solar ultraviolet radiation: monitoring, dosimetry and protection." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31222675.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Loughman, Robert Paul 1971. "A detailed numerical description of the solar aureole." Thesis, The University of Arizona, 1995. http://hdl.handle.net/10150/291355.

Full text

Abstract:

A new method of calculating accurate visible radiance values in the solar aureole region is derived in this study. The method interpolates between the radiance values output by a Gauss-Seidel flat atmosphere radiative transfer model using the radiative transfer equation itself. The method thereby produces accurate radiance values for arbitrary directions with only a slight increase in the required computational effort. The radiance and diffuse irradiance are then calculated for a variety of specified model atmospheres. The impact of polarization and the vertical stratification of aerosol particles is also investigated under various atmospheric conditions, and found to be relatively small under most realistic conditions. It is also found that some care must be taken when choosing the maximum aerosol radius at which to truncate the aerosol size distribution employed in the model atmosphere, to ensure that one does not exclude significant contributors to the scattered radiance field.

APA, Harvard, Vancouver, ISO, and other styles

12

Xiang, Xuwu. "The delta-Sobolev approach for modeling solar spectral irradiance and radiance." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/25801.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Conant, William Christopher. "Interactions between aerosol, water vapor, and solar radiation /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2000. http://wwwlib.umi.com/cr/ucsd/fullcit?p3025938.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Phillips, Amy Louise. "ABSOLUTE CALIBRATION OF, AND ATMOSPHERIC MEASUREMENTS USING, A MULTIBAND FIELD RADIOMETER (RADIOMETRY)." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275418.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Balaras, Constantinos Agelou. "Investigation of the dependence of atmospheric transmittance for beam radiation on clearness index." Thesis, Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/19156.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Robertson, Robert Voorhies. "Highly Physical Solar Radiation Pressure Modeling During Penumbra Transitions." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/73537.

Full text

Abstract:

Solar radiation pressure (SRP) is one of the major non-gravitational forces acting on spacecraft. Acceleration by radiation pressure depends on the radiation flux; on spacecraft shape, attitude, and mass; and on the optical properties of the spacecraft surfaces. Precise modeling of SRP is needed for dynamic satellite orbit determination, space mission design and control, and processing of data from space-based science instruments. During Earth penumbra transitions, sunlight is passing through Earth's lower atmosphere and, in the process, its path, intensity, spectral composition, and shape are significantly affected. This dissertation presents a new method for highly physical SRP modeling in Earth's penumbra called Solar radiation pressure with Oblateness and Lower Atmospheric Absorption, Refraction, and Scattering (SOLAARS). The fundamental geometry and approach mirrors past work, where the solar radiation field is modeled using a number of light rays, rather than treating the Sun as a single point source. This dissertation aims to clarify this approach, simplify its implementation, and model previously overlooked factors. The complex geometries involved in modeling penumbra solar radiation fields are described in a more intuitive and complete way to simplify implementation. Atmospheric effects due to solar radiation passing through the troposphere and stratosphere are modeled, and the results are tabulated to significantly reduce computational cost. SOLAARS includes new, more efficient and accurate approaches to modeling atmospheric effects which allow us to consider the spatial and temporal variability in lower atmospheric conditions. A new approach to modeling the influence of Earth's polar flattening draws on past work to provide a relatively simple but accurate method for this important effect. Previous penumbra SRP models tend to lie at two extremes of complexity and computational cost, and so the significant improvement in accuracy provided by the complex models has often been lost in the interest of convenience and efficiency. This dissertation presents a simple model which provides an accurate alternative to the full, high precision SOLAARS model with reduced complexity and computational cost. This simpler method is based on curve fitting to results of the full SOLAARS model and is called SOLAARS Curve Fit (SOLAARS-CF). Both the high precision SOLAARS model and the simpler SOLAARS-CF model are applied to the Gravity Recovery and Climate Experiment (GRACE) satellites. Modeling results are compared to the sub-nm/s^2 precision GRACE accelerometer data and the results of a traditional penumbra SRP model. These comparisons illustrate the improved accuracy of the SOLAARS and SOLAARS-CF models. A sensitivity analyses for the GRACE orbit illustrates the significance of various input parameters and features of the SOLAARS model on results. The SOLAARS-CF model is applied to a study of penumbra SRP and the Earth flyby anomaly. Beyond the value of its results to the scientific community, this study provides an application example where the computational efficiency of the simplified SOLAARS-CF model is necessary. The Earth flyby anomaly is an open question in orbit determination which has gone unsolved for over 20 years. This study quantifies the influence of penumbra SRP modeling errors on the observed anomalies from the Galileo, Cassini, and Rosetta Earth flybys. The results of this study prove that penumbra SRP is not an explanation for or significant contributor to the Earth flyby anomaly.
Ph. D.

APA, Harvard, Vancouver, ISO, and other styles

17

Paris, Mark V. "Model studies of solar spectral irradiance at the bottom and top of a cloudy atmosphere." Diss., Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/16900.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

James, Jonathan David. "Investigation into the composition and formation of atmospheric aerosol over the north-east Atlantic Ocean." Thesis, University of Birmingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324171.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Loeb, Norman Gary. "Evidence of three-dimensional cloud effects in satellite measurements of reflected solar radiation." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40181.

Full text

Abstract:

The purpose of this study is to assess the performance of the plane parallel model in analyzing satellite measurements of clouds, and to examine what role 3D cloud effects may play in explaining any discrepancies. Direct comparisons between one year of Earth Radiation Budget Satellite (ERBS) scanner radiances and plane parallel model calculations are carried out under different Sun-Earth-satellite viewing configurations over ocean between 30$ sp circ$N and 30$ sp circ$S. When the plane parallel model calculations are matched to observations at nadir on a pixel-by-pixel basis by adjusting cloud fraction and cloud optical depth, the resulting frequency distributions of cloud optical depth show a systematic shift towards larger values with increasing solar zenith angle, regardless of what assumptions are made in the calculations. On average, this increase in cloud optical depth is extremely large for solar zenith angles $ sbsp{ tilde}{>}$63$ sp circ.$ For the thinnest 50% of the clouds, the increase only occurs at very oblique sun angles, whereas it is observed at all solar zenith angles for the thickest 10% of clouds. The cause is traced to a fundamental flaw in plane parallel theory when applied to real clouds: at nadir the solar zenith angle dependence of model reflectance is opposite to that of the observations.
On average, differences between observed and plane parallel model reflectances are found to be less sensitive to view and relative azimuth angle than to solar zenith angle. For solar zenith angles less than ${ approx}63 sp circ,$ plane parallel model reflectances are within $ approx$10% of the observations. As solar zenith angle increases, differences between the observations and calculations increase at all view angles. At lower sun elevations, observed reflectances exceed plane parallel values by a constant amount at all view angles in the backscattering direction, while plane parallel model reflectances show a different view angle dependence from that observed in the forward direction. When comparisons are performed as a function of relative azimuth angle, no appreciable dependence in the reflectance difference is observed. Violation of the principle of reciprocity applied to real observations is shown to be mainly caused by the systematic difference in the solar zenith angle dependence between observations and plane parallel calculations.
Monte Carlo simulations involving stochastic, isotropic, scale-invariant broken cloud fields are carried out in order to show that, qualitatively, differences between observed and plane parallel reflectances are generally consistent with 3D theory. While much of the discrepancy between 3D and 1D reflectances can be attributed to the presence of cloud sides, affecting the illuminated cloud area, it is shown that the slope of the illuminated cloud top surfaces may also play an important role.

APA, Harvard, Vancouver, ISO, and other styles

20

THOMASON, LARRY WILLIS. "EXTINCTION OF NEAR INFRARED SOLAR RADIATION AS A MEANS FOR REMOTE DETERMINATION OF ATMOSPHERIC WATER VAPOR." Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/188078.

Full text

Abstract:

A computationally efficient and accurate model is derived for the calculation of the atmospheric transmittance along inhomogeneous paths and within spectral bands dominated by molecular line absorption. It is a Stieltjes integration of transmission weighted by the frequency of occurrence of absorption coefficient within the band. Path inhomogeneitites are accounted for by assuming that the rank of absorption coefficient at any wavenumber is independent of temperature and pressure. The technique is then applied to the ground based radiometric determination of precipitable water. It is found that the technique predicts the behavior of the ρστ water vapor absorption band very well. An RMS disagreement of 11% is found when the model predictions are compared to radiosonde determinations of precipitable water. The model is also applied to the determination of vertical water vapor distributions in the stratosphere given measured effective optical depths as a function of tangent height from a limb scanning satellite. A new iterative reduction technique is introduced which incorporates the transmission model and it is shown to be both numerically stable and rapidly convergent. A comparison of the results with an independent reduction technique shows good overall agreement with a small systematic difference above 20 km. The uncertainty in the measurements, which yields solution uncertainties on the order of 30%, renders this systematic difference unimportant.

APA, Harvard, Vancouver, ISO, and other styles

21

Feng, Jian 1971. "Solar radiation in the Mackenzie River Basin : retrieval from satellite measurements and evaluation of atmospheric models." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=38186.

Full text

Abstract:

Accurate determination of solar flux at the top of the atmosphere (TOA), which can only be made from satellite observations, is essential for climate studies. In the present study, we developed a new technique to derive the solar fluxes at the TOA and at the surface from operational meteorological satellites. Two key steps in the technique are the narrowband to broadband (NTB) conversion and deriving the net solar flux at the surface from TOA observations. We developed a new NTB conversion algorithm from ScaRaB observations and radiation transfer model simulations. In deriving the net solar fluxes at the surface from TOA measurements, the effects of absorbing aerosols have been investigated.
The technique described above has been applied to AVHRR data to derive a dataset of solar flux in the Mackenzie River Basin (MRB) for the Canadian GEWEX Enhanced Study (CAGES) period from June 1998 to September 1999. The derived net solar fluxes at the surface were evaluated with the surface measurements in the basin and good agreement was achieved.
Radiation fields from two atmospheric models used in the Mackenzie GEWEX Study (MAGS) project, the Canadian Regional Climate Model (CRCM) and the Global Environmental Multiscale (GEM) model, were evaluated against satellite retrievals of radiation fluxes in the present study. It was found that the CRCM simulated the TOA reflected flux well in the MRB for the summer of 1994, but large biases were found in the partition of absorbed solar radiation between the atmosphere and the earth's surface. The net surface solar radiation was found to be overestimated by about 15% in the CRCM. Evaluation of the preliminary output from the new version of CRCM shows substantial improvement. Evaluation of radiation fields from the GEM model shows good agreement under clear skies, but under cloudy skies, the TOA albedo simulated by the GEM model in the MRB was about 30% lower than observations for the summer of 1999.

APA, Harvard, Vancouver, ISO, and other styles

22

Voisin, Nathalie 1978. "Sensitivity of the hydrology and the energy budget of the Mackenzie River Basin to uncertainties in solar radiation." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=79154.

Full text

Abstract:

One of the goals of the Mackenzie GEWEX Study (MAGS) is to model the critical components of the water and energy cycles that affect the climate of the Mackenzie Basin. The land surface - hydrological model WATCLASS is used to simulate the energy and water transports at and below the surface. Atmospheric input to WATCLASS is provided by the output from the atmospheric model GEM. There may be significant uncertainties in the GEM incoming solar radiation due largely to difficulties in simulating clouds and their radiative properties. The question that we address is how these uncertainties affect the simulation of the energy and water budgets of this northern river watershed.
To assess this sensitivity, two series of two WATCLASS model runs are compared. Both runs are driven by atmospheric data from GEM for the 1998--99 water-year, but in the second run shortwave radiation fluxes retrieved from satellite measurements replace the GEM fluxes. Land cover differs in the two series of runs and so provides an assessment of the sensitivity to vegetation variability. Results show that the atmospheric model overestimates the incoming solar radiation field by 36%. This results in an increase in the basin annual average surface temperature of about 1°C and an overestimation in net longwave radiation, and sensible and latent heat fluxes. Snowmelt starts earlier with a decreased first snowmelt peak in runoff and discharge hydrographs. The overall consequence is an annual discharge underestimation.

APA, Harvard, Vancouver, ISO, and other styles

23

Garvin, Theresa Dawn. "Evidence, policy and practice in environmental health : an international case study of sun safety /." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0033/NQ66209.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Sanchez, Romero Alejandro. "Sunshine duration as a proxy of the atmospheric aerosol content." Doctoral thesis, Universitat de Girona, 2016. http://hdl.handle.net/10803/394045.

Full text

Abstract:

One of the most important radiative properties of aerosols is their optical thickness (AOD), which is closely linked to the total burden of atmospheric aerosols. On the contrary, we do avail of long time series of sunshine duration (SD) measurements, which is defined as the total time length of those sub-periods for which the direct solar irradiance exceeds a certain threshold. In the past, the Campbell-Stokes sunshine recorder (CSSR) has been the most common instrument for measuring SD. Specifically, SD is obtained measuring the length of the burn produced on a cardboard. The principal goal of the present thesis is to investigate the suitability of sunshine observations, as well as the width of the burn on the cards, for detecting changes in atmospheric aerosol load for both high time resolution and long time scales. The initial hypothesis is that an increase of AOD reduces both SD and the burn width.
Una de les propietats radiatives més importants dels aerosols atmosfèrics és el seu espessor òptic (AOD), que està molt vinculat a la càrrega total d’aerosols en l’atmosfera. Per altra banda, existeixen llargues series temporals d’insolació (SD), que es defineix com la suma de subperíodes en què la irradiància solar directa excedeix un cert llindar. En el passat, l’heliògraf Campbell-Stokes ha estat l’instrument més comú per la mesura de SD, obtinguda a partir de la longitud de la cremada produïda en una banda de cartolina. L’objectiu principal d’aquesta tesi ha estat investigar la idoneïtat de la utilització de mesures de SD, així com l’amplada de les cremades en les cartolines, per tal de detectar canvis en la càrrega d’aerosols atmosfèrics, tant en alta resolució temporal com en llargues escales temporals, partint de la hipòtesis de que un augment de l’AOD redueix tant la mesura de SD com l’ample de la cremada.

APA, Harvard, Vancouver, ISO, and other styles

25

Mooring, Raymond Derrell. "On using empirical techniques to optimize the shortwave parameterization scheme of the community atmosphere model version two global climate model." Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-04172005-231106/unrestricted/mooring%5Fraymond%5Fd%5F200505%5Fphd.PDF.

Full text

Abstract:

Thesis (Ph. D.)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2005.
Dickinson, Robert, Committee Chair ; Jenkins, Gregory, Committee Member ; Vidakovic, Brani, Committee Member ; Fu, Rong, Committee Member ; Cunnold, Derek, Committee Member. Vita. Includes bibliographical references.

APA, Harvard, Vancouver, ISO, and other styles

26

Li, Peng. "Temporal and Spatial Variability of Surface Solar Radiation over the South-West Indian Ocean and Reunion Island : Regional Climate Modeling." Thesis, La Réunion, 2015. http://www.theses.fr/2015LARE0021/document.

Full text

Abstract:

Ce travail documente la variabilité spatiale et temporelle du rayonnement solaire à la surface sur le sud-ouest de l'océan Indien (SOOI) et l'île de La Réunion à l'aide de deux modèles régionaux de climat (MRC) : les modèles RegCM et WRF. La première partie de ce travail est dédiée à l'analyse de la variabilité temporelle du rayonnement solaire à l'aide du modèle RegCM sur le SOOI avec une résolution spatiale modérée (50km). S'agissant du premier travail sur la modélisation régionale du climat pour l'étude du rayonnement solaire dans le SOOI, une première série de tests pour illustrer les performances du modèle et sa sensibilité au choix des paramétrisations physiques (transfert radiatif, convection), à la taille du modèle, et à la résolution spatiale, est effectuée. Le schéma radiatif par défaut, le schéma CCM, et le schéma convectif mixte : Grell sur les terres et Emanuel sur les océans, donnent les résultats les plus satisfaisants pour la région, comparés aux autres options disponibles. La variabilité climatique interannuelle, intrasaisonnière et jour-à-jour est ensuite examinée sur la base des indices climatiques. Dans un premier temps, plusieurs paramètres (vent horizontal, température, humidité relative) issus des réanalyses ERA-Interim et utilisés comme paramètres d'entrée pour le modèle RegCM, sont analysés en lien avec ceux correspondant fournis en sortie du modèle, pour vérifier l'aptitude du modèle à maintenir les signaux ENSO (El-Nino Southern Oscillation), IOD (Indian Ocean Dipole), MJO (Madden-Julian Oscillation) et les Talwegs Tropicaux-Tempérés (TTT). Dans un second temps, le rayonnement solaire à la surface simulé par le modèle RegCM est mis en lien avec ces différents modes de variabilité. La seconde partie du travail est consacrée à l'analyse de la variabilité spatiale du rayonnement solaire à la surface à La Réunion à l'aide du modèle WRF à très haute résolution spatiale (750m) pour différentes échelles de temps : interannuelle, intrasaisonnière, jour-à-jour. Une classification est appliquée sur les sorties de rayonnement produites par WRF, et le lien avec la circulation atmosphérique de grande échelle est analysé dans chacune des classes. Les résultats de la modélisation sont validés à l'aide des données d'observations du réseau Météo France et des produits satellite CM SAF. Les résultats indiquent que les MRC ont la capacité de représenter la variabilité temporelle et spatiale du rayonnement solaire à La Réunion
This work documents the temporal and spatial variability of surface solar radiation (SSR) over the southwest Indian Ocean (SWIO) and Reunion Island using two complementary Regional Climate Models (RCMs): RegCM4 and WRF. The first part of the work is dedicated to the analysis of the temporal variability of SSR based on RegCM4 over the SWIO at a moderate spatial resolution (50km). Because RegCM4 is the first RCM that focuses on the solar radiation research over the SWIO region, a first series of test experiments with this model to illustrate the model performance and its sensitivity to the choice of the physical parameterizations (radiation, convection), the domain size, and the spatial resolution, are performed. The default CCM radiative and the mixed convective scheme: Grell scheme over land and Emanuel scheme over ocean, give better performance over the SWIO compared to the other available options. The interannual, intraseasonal and synoptic climate variability is then examined through the climate indices and several ERA-Interim parameters (U, V, T and RH) are firstly analyzed along with the corresponding RegCM4 output data to check whether the RegCM4 model forced by ERA-Interim reanalyses is able to maintain the El-Nino Southern Oscillation (ENSO), the Indian Ocean Dipole (IOD), the Madden-Julian Oscillation (MJO) and the Tropical Temperate Trough (TTT) signals. Secondly, simulated SSR in association with the different modes of variability is examined. In the second part, SSR spatial variability over Reunion Island is analyzed based on WRF simulations at very fine resolution (750m) for seasonal, intraseasonal, and daily time scales. Clustering classification is applied to WRF simulated SSR over Reunion and the effect from the atmospheric circulation is checked together. Météo France observations and CM SAF are used to validate the results of the model. The results indicate that regional climate models have the ability to present the temporal and spatial variability of SSR over Reunion

APA, Harvard, Vancouver, ISO, and other styles

27

Lamy, Kévin. "Projection Climatique du Rayonnement Ultraviolet au cours du 21ème siècle : impact de différents scénarios climatiques." Thesis, La Réunion, 2018. http://www.theses.fr/2018LARE0018/document.

Full text

Abstract:

Suite à la signature du Protocole de Montréal en 1987, la concentration atmosphérique des substances destructrices d’ozone (ODS) est en baisse. La couche d’ozone montre des signes de récupération (Morgenstern et al. 2008a). Toutefois, l’émission des gaz à effet de serre (GHG) est en augmentation et devrait affecter au cours du 21ème siècle la distribution et les niveaux d’ozone dans l’atmosphère terrestre. En particulier, la modélisation du climat futur montre des signes d’accélération de la circulation de Brewer-Dobson transportant l’ozone de l’équateur vers les pôles. L’ozone est un constituant chimique important de l’atmosphère. Bien que nocif dans la troposphère, il est essentiel à la vie sur Terre grâce à sa capacité d’absorption d’une grande partie du rayonnement ultraviolet (UV) provenant du Soleil. Des modifications dans sa variabilité temporelle ou géographique impliqueraient des changements d’intensité du rayonnement UV à la surface de la Terre (Hegglin et al. (2009), Bais et al. (2011)). Le rayonnement UV à la surface affecte toute la biosphère. Les interactions entre rayonnement UV et écosystèmes terrestres et aquatiques sont nombreuses. Ces interactions ont des effets sur les cycles biogéochimiques et engendrent des rétroactions positives et négatives sur le climat (Erickson III et al., 2015a). La capture du CO2 atmosphérique par photosynthèse des plantes terrestres en est un exemple (Zepp et al., 2007a). Dans l’océan la pompe biologique du CO2 par la photosynthèse du phytoplancton est aussi directement affecté par la variabilité du rayonnement UV (Hader et al., 2007a). Pour l’homme le rayonnement UV est nécessaire car il participe à la photosynthèse de la vitamine D (Holick et al., 1980), mais une surexposition à des niveaux d’intensité élevés du rayonnement UV est la cause principale du développement de cancer de la peau (Matsumura and Ananthaswamy, 2004). L’objectif de ce travail de thèse est d’analyser l’évolution possible du rayonnement UV au cours du 21ème siècle, en particulier aux tropiques sud, dans le cadre des modifications climatiques attendues. Une première partie de ce travail consiste à modéliser le rayonnement UV en ciel clair dans les tropiques grâce au modèle TUV (Madronich et al., 1998) et à comparer les résultats aux mesures sols réalisées à la Réunion. Cette première partie permet l’utilisation future du modèle aux tropiques avec un bon niveau de confiance. La sensibilité du modèle de transfert radiatif en fonction de différents paramètres d’entrée est analysée (section efficace d’absorption de l’ozone,spectre extraterrestriel du soleil, ...). Les sorties du modèle sont ensuite validées à partir de mesures UV spectral au sol obtenues grâce à un spectromètre BENTHAM DM300n. Un filtrage ciel-clair des données au sol est opéré à partir de mesures de flux et de l’algorithme de Long and Ackerman (2000). Les projections climatiques des indices UV (Mc Kinlay and Diffey, 1987) sont réalisées par la suite. Pour cela, on utilise les sorties de plusieurs modèles de Chimie-Climat participant à l’exercice d’inter-comparaison CCMI (Chemistry Climate Model Initiative), couplées aux modèle TUV, validé en première partie dans les tropiques. L’exercice CCMI consiste à projeter le climat et la chimie Terrestre jusqu’en 2100 selon différents scénarios. Ces sorties décrivant la chimie et physique de l’atmosphère servent d’entrée au modèle de transfert radiatif, on obtient alors le rayonnement UV jusqu’en 2100 pour différents scénarios. Une première analyse comparative de l’UV obtenue pour quatre scénarios d’émissions (RCP2.6/4./6.0/8.5, Meinshausen et al., 2011) est effectuée. La fin du travail consiste à étudier l’impact des ODS, GHG et aérosols sur l’évolution du rayonnement UV au cours du 21ème siècle, avec un focus particulier sur les tropiques de l’hémisphère sud
Following the 1987 Montreal Protocol, atmospheric concentrations of ozone-depleting substances are decreasing. The ozone layer shows signs of recovery. Nonetheless, greenhouse gases emissions (GHG) are rising et should affect the ozone distribution in the atmosphere. Ozone is an important due to his ability to absorb ultraviolet (UV) radiation. The goal of this work is to analyse the possible evolution of UV radiation through the 21st century, particularly in the tropics, for possible climate modification. The first part of this work is to UV in clear-sky in the tropics with the TUV (Madronich et al., 1998) model and to compare against ground-based observations made on Reunion Island. This validation allows the utilisation of TUV in the tropics with a good confidence level. The sensitivity of the model is analysed for multiple parameters. Modelling output is validated against spectral ground-based measurement. Climate Projection of UVI (Mc Kinlay and Diffey, 1987) are then realized with the use of output from model participating in the CCMI ( Model Initiative) exercise and the TUV model. CCMI output describes the chemistry and physics of the atmosphere through the 21st century for four climate scenarios (RCP2.6/4.5/6.0/8.5), they are used as input for the TUV model in order to obtain UV radiation. ODS, GHG and aerosols impact on UVI evolution is analysed

APA, Harvard, Vancouver, ISO, and other styles

28

Palmieri, Anderson Marcelli. "Desenvolvimento de sistema automatizado de baixo custo para coleta e armazenamento de dados de variáveis climáticas: aplicações no ambiente agrícola." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/11/11131/tde-18022010-142019/.

Full text

Abstract:

As variáveis climáticas como temperatura do ar, umidade relativa do ar e radiação solar exercem grande influência sobre a produção agrícola, sendo capazes de ocasionar perdas durante o processo produtivo, acarretando em um aumento considerável no preço do produto final. Desse modo, a presente pesquisa teve por objetivo, desenvolver um sistema automatizado de baixo custo, tendo como base o microcontrolador Basic Step 1, o qual gerenciou um circuito eletrônico capaz de coletar e armazenar dados das respectivas variáveis climáticas, em um dispositivo de memória flash com conexão USB (pen drive). Além disso, o equipamento conta com o Data Basic - Software, o qual foi elaborado de modo a permitir ao usuário a análise dos dados coletados, com fácil visualização, devido à sua interface gráfica, bem como seu manuseio pelo fato de estabelecer uma conexão com planilha eletrônica (EXCEL). Os resultados mostraram a viabilidade do uso do sistema automatizado (Data-Basic) o qual funcionou com regularidade e precisão ao coletar e armazenar o sinal de tensão contínua enviado pelos 3 sensores. Assim, os dados coletados pelos sensores de umidade relativa do ar e temperatura, HIH 4000 e LM35, respectivamente demonstraram-se confiáveis, evidenciando a viabilidade do uso do equipamento, embora o sensor de radiação solar tenha demonstrado fragilidade e necessidade de uma pré-calibração antes de sua instalação. O custo de montagem do equipamento foi cerca de 50% menor em relação aos data loggers portáteis e apresentou fácil manutenção, pois permite a troca de placas como a do Basic Step1 ou do módulo de gravação PenBS, sem contar que os sensores são externos o que facilita também sua substituição caso seja necessário. Desse modo, pôde-se concluir a viabilidade de utilização deste instrumento mediante o seu baixo custo de produção, porém para longos períodos de coleta, recomenda-se a utilização de uma bateria externa a fim de se evitar a perda de dados pela falta de energia da rede elétrica, além disso, durante o processo de instalação, devem ser tomadas precauções no sentido de evitar a oxidação dos sensores e erros de medida, que podem afetar diretamente a qualidade dos dados coletados.
Climate variables such as air temperature, air humidity and solar radiation have a significant impact on agricultural yield. These variables affect the production process, and have a considerable influence on final product prices. The objective of this research, therefore, was to develop a low-cost, automated system, based on the Basic Step 1 microcontroller, to collect and store climate data in a flash memory device with USB connection (pen drive). In addition, the system includes the Data Basic Software, developed to enable the user to visualize the data in a graphical user interface and to manipulate the data in a spreadsheet (EXCEL). The results demonstrated the viability of the automated system (Data-Basic), which worked with regularity and precision in measuring and storing continuous voltage signals from 3 sensors. The measured data from the air humidity and temperature sensors, HIH4000 and LM35, were reliable, showing the viability of the system, while the radiation sensor was fragile and required pre calibration before installation. The cost of mounting the equipment was approximately 50% of that of a portable data logger. The system is easy to maintain, allows for the replacement of elements such as the microcontroller (Basic Step 1) or the storage module (PenBS), and has external sensors which can be replaced if necessary. It is feasibility to use this tool because of its low production cost. However, for extended periods of data collection, it is recommended that an external battery be added to prevent data loss during power outages. During the installation process, precautions should be taken to prevent the oxidation of the sensors, which would result in measurement errors, directly affect the quality of data collected.

APA, Harvard, Vancouver, ISO, and other styles

29

Barabash, Victoria. "Investigation of Polar Mesosphere Summer Echoes in Northern Scandinavia." Doctoral thesis, Umeå University, Physics, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-176.

Full text

Abstract:

This PhD thesis deals with phenomena which are closely related to the unique thermal structure of the polar summer mesosphere, namely Polar Mesosphere Summer Echoes (PMSE). PMSE are strong radar echoes commonly observed by VHF MST radars from thin layers in the 80-90 km altitude interval at high latitudes during summer. They follow a seasonal pattern of abrupt appearance in late May and a gradual disappearance in mid-August. This period corresponds roughly to the time between the completion of the summer time cooling of the polar mesopause to the time of reversal of the mesospheric circulation to autumn condition. In this connection, PMSE are associated with the extremely low temperatures, i.e. below 140 K, which are unique to the polar summer mesopause. Traditional theories of radar (partial) reflection and scattering have been unable to explain the PMSE and the exact mechanism for their occurrence remains unclear despite the steadily increasing interest in them over the past 20 years. Currently accepted theories regarding the mechanism giving rise to PMSE agree that one of the conditions needed for enhanced radar echoes is the presence of low-mobility charge carries such as large cluster ions and ice aerosols which capture the ambient electrons. It has been established that the PMSE are in some way associated with noctilucent clouds (NLC), layers of ice crystals, which constitute the highest observed clouds in the earth’s atmosphere. PMSE occurrence and dynamics are also found to be closely connected with the planetary and gravity waves.

Observations of PMSE presented in this thesis have been carried out by the Esrange MST radar (ESRAD) located at Esrange (67°56’N, 21°04’E) just outside Kiruna in northernmost Sweden. The radar operates at 52 MHz with 72 kW peak power and a maximum duty cycle of 5%. The antenna consists of 12x12 array of 5-element Yagis with a 0.7l spacing. During the PMSE measurements the radar used a 16-bit complementary code having a baud length of 1mS. This corresponds to height resolution of 150 m. The sampling frequency was set at 1450 Hz. The covered height range was 80-90 km. The presence of PMSE was determined on the basis of the radar SNR (signal-to-noise ratio). The PMSE measurements have been made during May-August each year since 1997.

PMSE seasonal and diurnal occurrence rates as well as dynamics have been studied in connection with tidal winds, planetary waves, temperature and water vapor content in the mesosphere (Papers I, IV and VI). Simultaneous and common-volume observations of PMSE and noctilucent clouds have been performed by radar, lidar and CCD camera (Paper V). Correlation between variations in PMSE and variations in extra ionization added by precipitating energetic electrons or high-energy particles from the Sun has been examined (Papers II and III). Possible influence of transport effects due to the electric field on PMSE appearance has been studied during a solar proton event (Paper III).

APA, Harvard, Vancouver, ISO, and other styles

30

Burnett, Benjamin F. "Exploratory Eddy Covariance Measurements of Surface Heat and CO2 Fluxes in the Roughness Sublayer of an Urban Environment." PDXScholar, 2010. https://pdxscholar.library.pdx.edu/open_access_etds/401.

Full text

Abstract:

In this study eddy covariance was used to measure sensible heat, latent heat, and carbon dioxide fluxes for the months of August, September, and October of 2009 within the roughness sublayer (RSL) of the urban center of Portland, OR. Vehicle traffic and solar radiation were also measured for the month of October. Flux measurements were compared with measurements from other urban areas as a test of reasonableness. CO₂ fluxes were nearly always positive and were strongly correlated with the weekday diurnal traffic cycle. CO₂ fluxes averaged 6.6 μmol/m^²s, which is less than other published measurements in urban areas. Sensible and latent heat fluxes followed the expected diurnal profile associated with solar radiation. Average sensible heat flux decreased as the season changed from summer to fall, moving from an average of 39 W/m^² in August to 12 W/m^² in October. A corresponding increase in latent heat flux was observed during this period, changing from an average of 10 W/m^² in August to 17 W/m^² in October. Heat flux behavior and amplitude was consistent with other urban measurements, though amplitude varies considerably from city to city. Stationarity was shown to positively influence measured CO₂ fluxes, but to have little effect on measured heat fluxes. Preliminary comparisons of October sensible heat and CO₂ fluxes to an inventory-based estimate of vehicle emissions indicate that eddy covariance measurements underestimate the true fluxes by 50%.

APA, Harvard, Vancouver, ISO, and other styles

31

Salgado, Paula Rodrigues. "Fenóis totais no cafeeiro em razão das fases de frutificação e do clima." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/11/11136/tde-26042005-145455/.

Full text

Abstract:

Os vegetais apresentam defesa natural contra os fatores externos, bióticos e abióticos, por meio da síntese de compostos fenólicos no metabolismo secundário, as quais variam com as fases fenológicas e com o clima. O aumento dos compostos fenólicos nas plantas está, diretamente, relacionado com a resistência à infecção por patógenos e à infestação de pragas. Entretanto, pouco se sabe sobre a variação dos teores dessa substância durante os estádios fenológicos do cafeeiro, em particular, nas fases de frutificação, e em razão das condições climáticas. Tais conhecimentos são fundamentais para a previsão dos riscos de ataques aos vegetais, uma vez que a defesa natural da planta deve mudar ao longo do ciclo. O experimento foi realizado em uma cultura de Coffea arabica L., cultivar Obatã IAC 1669-20, instalada no campo experimental do Departamento de Produção Vegetal, da Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Piracicaba/SP. Para a realização do experimento foi adotado o delineamento experimental inteiramente casualizado, utilizando quatro tratamentos (plantas com e sem frutos - folhas dreno e plantas com e sem frutos - folhas fonte) e cinco repetições constituídas por plantas individuais. Após a análise de variância dos resultados foi aplicado o teste t de Student ao nível de 5 % de significância para a comparação das médias entre os tratamentos. Os teores de fenóis totais (µg g-1) foram extraídos das folhas maduras (fonte) e novas (dreno) e analisados em relação à produção de café, fenologia e clima. As variáveis climáticas adotadas foram temperatura atmosférica (média, mínima e máxima; oC), radiação global (MJ m-2 dia-1) e insolação diária (h dia-1). Durante a condução do experimento foram realizadas avaliações de altura da planta (cm), diâmetro do caule (mm) e comprimento de ramos plagiotrópicos (cm) para determinar as respectivas taxas de crescimento vegetativo das plantas. As quantidades de fenóis totais determinadas nas plantas com produção (17.40 µg g-1 e 13.89 µg g-1 folhas dreno e fonte, respectivamente) e sem produção de café (18.65 µg g-1 e 12.76 µg g-1 folhas dreno e fonte, nessa ordem) não variaram. No entanto, a concentração de fenóis totais nas folhas novas (dreno) das plantas com e sem produção de café foi maior que a quantidade determinada nas folhas maduras (fonte), da ordem de 25 % e 46 %, respectivamente. A síntese de fenóis nas fases de expansão (16.35 µg g-1) e granação dos frutos (14.68 µg g-1) foi 31 % inferior em relação às quantidades determinadas na fase de maior produção dessas substâncias fruto em maturação (21.24 µg g-1). A metabolização de fenóis totais depende, indiretamente, da temperatura (oC) e da radiação global (MJ m-2 dia-1), apresentando tendência inversa em relação a estas variáveis climáticas. A orientação do manejo fitossanitário deve levar em consideração as épocas em que há comprometimento da defesa natural da planta, em relação à produção de substâncias protetivas os fenóis.
The vegetables show a natural defense against external factors, biotic and abiotic, by the synthesis of the phenolic compounds in the secondary metabolism, which varies with the maturity state and with the climate. The increase of phenolic compounds in the plants is directly related to the resistance to the infection thought pathogens and insect infestation. However, little is known about the variation in the content of this substance during the maturity state of the coffee tree, particularly in the fructification phases due to the climatic variations. Such knowledge is the base for the risks analyses of attacks to vegetables, since the natural defense of the plant shall change during the cycle. The experiment was carried out in a Coffea arabica L. crop, to cultivar Obatã IAC 1669-20, installed in the experimental field of the department of vegetal production of the Escola Superior de Agricultura "Luiz de Queiroz", University of São Paulo, Piracicaba/SP. For the accomplishment of the experiment it was adopted a totally randomized experimental design, using four treatments (plants with and without fruits drain leaves and plants with and without fruits source leaves) and five repetitions consisting of individual plants. After analysing the variance of the results it was applied Student t test at the level of 5 % of significance to compare the averages between the treatments. The total phenol grade (µg g-1) have been extracted from the mature (source) and new (drain) leaves and have been analyzed in relation to the coffee yield, phenology and climate. The climatic conditions adopted were atmospheric temperature (average, minimum and maximum; oC), global radiation (MJ m-2 day-1) and daily insolation (h day-1). During the conduction of the experiment it was analyzed the evaluations of the height (cm), diameter (mm) and length of the reproductive branches (cm) to determine the respective vegetative growth rates of the plants. The determined amounts of total phenols in the plants with production (17.40 µg g-1 and 13.89 µg g-1 drain and source leaves, respectively) and without coffee production (18.65 µg g-1 and 12.76 µg g-1 drain and source leaves, respectively) did not varied. However, the total phenol concentrations in new leaves of the plants with and without coffee production were greater than the amount determined in mature leaves around 25 % and 46 %, respectively. The secondary substance synthesis in the phases of expansion (16.35 µg g-1) and grain filling of the fruits (14.68 µg g-1) was 31% lower than the amounts determined in the phase of the greatest production of these substances - fruit in maturation (21.24 µg g-1). The total phenol metabolization depends indirectly on the temperature (oC) and on the global radiation (MJ m-2 day-1), presenting inverse trend in relation to these climatic variable. The orientation of the crop protection managing shall take into consideration the period when it has endangerment of the natural defense of the plant.

APA, Harvard, Vancouver, ISO, and other styles

32

Stephenson, Judy Ann Elizabeth. "Solar influences on Polar ozone." Thesis, 1994. http://hdl.handle.net/10413/5079.

Full text

Abstract:

Measurements by the TOMS instrument aboard the Nimbus 7 satellite, of total column ozone over polar regions have been studied to determine the effects of solar induced natural ozone modulation. Two different analysis methods were employed to ascertain short term (days to months) and long term (months to years) solar influences on polar ozone. Bursts of intense solar activity can result in solar proton events (SPE's). The high energy protons, originating in solar flares, produce secondary electrons which can generate large concentrations of odd nitrogen in the middle atmosphere. These reactive species can catalytically destroy ozone. Three case studies are presented in an attempt to quantify the effect of SPE's on ozone mass over a latitude region 90 to 70°. In order to monitor the ozone response following a SPE over both hemispheres simultaneously, the SPE must occur during the equinox period when both poles are irradiated. Fortuitously, a SPE was recorded in March 1989, the analysis of which forms a case study in this thesis. Ozone depletions of 7.4 x 10 to the power of 9 kg for the south polar cap and 8.0 x 10 to the power of 9 kg for the north polar cap indicate the degree of symmetry for this event. Longer term effects of solar variability are investigated by Fourier techniques. A Fourier transform of eleven years of total ozone mass values, over the region 90 to 70° S, was performed. Inspection of the Fourier spectrum reveals peaks associated with solar cycle, annual and semi-annual oscillations, that may be attributed directly to solar variation. Other peaks, corresponding to QBO and ENSO periodicities, may be ascribed to indirect solar influences i.e. thermally driven dynamics. Finally, a comparison between the phase of the solar cycle peak in this spectrum with that in a spectrum of daily values of solar radio flux, reveals that the austral polar ozone solar cycle periodicity lags solar forcing by 2.8 years. Portions of chapters have been reported at the 1990 South African Institute of Physics Annual Conference, University of Port Elizabeth, South Africa and as a poster at the 1992 Quadrennial Ozone Symposium, Charlottesville, United States of America, 4-13 June 1992. In addition, various parts of this work has been submitted for publication, viz: Stephenson, J. A. E. and M. W. J. Scourfield, Importance of energetic solar protons in ozone depletion, Nature, 352, 137: 1991.
Thesis (Ph.D.)-University of Natal, Durban, 1994.

APA, Harvard, Vancouver, ISO, and other styles

33

Martins, I. "Neural models project for solar radiation and atmospheric temperature forecast." Master's thesis, 2009. http://hdl.handle.net/10400.1/3993.

Full text

Abstract:

Dissertação de mest., Engenharia Electrónica e Telecomunicações, Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2009
This work arises from the necessity of temperature and solar radiation forecast, to improve the Heating, Ventilating, and Air Conditioning (HVAC) systems e ciency. To do so, it was necessary to determine neural models capable of such forecast. The chosen characteristics were solar radiation and temperature because these two characteristics directly a ect the room temperature inside a building. This forecast system will be implemented on a portable computational device, so it must be built with low computational complexity. During this dissertation the various research phases are described with some detail. The applications were developed on Python programming language due to it library collection. In this task several algorithms were developed to determine the cloudiness index. The results of these algorithms were compared with the results obtained using neural models for the same purpose. In solar radiation and temperature forecast only neural models were used. The cloudiness index forecast was not implemented as this is only an intermediate step; instead measured values of cloudiness index were used for the solar radiation forecast. Regarding the solar radiation forecast two neural models were implemented and compared, one of the models has an exogenous input, the cloudiness index forecast, and the other one is simply a time series. This models were compared to determine if the inclusion of the cloudiness index forecast improves solar radiation forecast. In temperature forecast only one model will be presented, a Nonlinear AutoRegressive with eXogenous input (NARX) model, with solar radiation forecast as exogenous input. All the neural models are radial Basis Function (RBF) and there structure was determined using a Multi-Objective Genetic Algorithm (MOGA). The models were used to determine cloudiness index, forecast solar radiation and temperature.

APA, Harvard, Vancouver, ISO, and other styles

34

Dikty, Sebastian [Verfasser]. "Short-term variations in middle atmospheric ozone induced by solar forcing / von Sebastian Dikty." 2010. http://d-nb.info/100232470X/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Gomes, João Mealha. "Implementation of an intelligent sensor for measurement and prediction of solar radiation and atmospheric temperature." Master's thesis, 2011. http://hdl.handle.net/10400.1/8408.

Full text

Abstract:

Dissertação de mestrado, Engenharia Electrónica e Telecomunicações, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2011
The aim of this study was to develop an intelligent sensor for aquiring temperature, solar radiation and cloudiness index data, and use these measured values to predict temperature and solar radiation in a near future. The prototype produced could ultimately be used in systems related to thermal comfort in buildings and the e cient and intelligent use of energy resources. So to incorporate these functionalities, a small and portable prototype was developed, which consisted in: a CCTV camera with a sh-eye lense for sky images aquisition; a computer of format mini-itx with a Linux operating system, for data aquisition and processing; a GPS to enable automatic use independent of the system's geographical position; a pyranometer for regular measurements of solar radiation; a temperature probe, for regular measurements of outdoor temperature; a shadow band to eliminate the sun's are e ect on sky images; Arduino, an open source electronics prototyping platform that aquires data from the temperature and solar radiation sensors, as well as processing the data provided by the GPS and controlling the shadow band; neural networks of the type NARX (not developed in this present study), which use the aquired data to forecast the cloudiness index, solar radiation and temperature, in the next four hours. The system was programmed to aquire data, both from the sensors and the camera, every five minutes.

APA, Harvard, Vancouver, ISO, and other styles

36

Winkler, Holger [Verfasser]. "The response of middle atmospheric ozone to solar proton events in a changing geomagnetic field / von Holger Winkler." 2008. http://d-nb.info/990463621/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Chu, Shaoping. "A study of the impact of doubling carbon dioxide and solar radiation variations on the climate system." Thesis, 1994. http://hdl.handle.net/1911/16723.

Full text

Abstract:

The exchange of moisture and heat between the atmosphere and the Earth's surface fundamentally affect the dynamics and thermodynamics of the climate system. In order to trace moisture flow through the climate system and examine its impact on climate, a hydrologic cycle and a land energy balance have been developed and incorporated into a coupled climate-thermodynamic sea ice (CCSI) model. The expanded CCSI model has been tested by comparing computed climate parameters with available observations and GCM modeling results. In general, the expanded model does a good job in simulating the large scale features of the atmospheric circulation and precipitation in both space and time. The expanded model has been used to examine the possibility that increased levels of CO$\sb2$ in the atmosphere may induce the growth of Northern Hemisphere ice sheets. Results of the study indicate that if summer ice albedo is high enough, and there is some mechanism for initially maintaining ice through the summer season, then it may be possible to have ice sheet growth under the conditions CO$\sb2$ induced warming, mainly the result of decreased summer ice melt in response to the higher land ice albedo, and not an increase in precipitation. The expanded model has also been used to examine the impact of Milankovitch solar radiation variations on the climate system, to study the mechanisms that produce glacial-interglacial cycles, especially with respect to the initiation of ice sheets. The results show the Milankovitch solar radiation variations affect the climate system most in the polar regions with the mean annual surface air temperature varying directly in response to changes in the annually averaged incoming solar radiation. However, the seasonal variations in the surface air temperatures are much more complex with large magnitude variations for brief times during the year. The study indicates that ice sheets may start to grow under the conditions of low insolation that occurred at 25, 70, and 115 kyr BP and a land ice minimum albedo of 0.53, with the largest growth rate at 115 kyr BP, approximately when the current 100 kyr cycle began as observed in the geological record.

APA, Harvard, Vancouver, ISO, and other styles

38

Chapman, Robert Douglas. "Estimation of vapour pressure and solar radiation in South Africa." Thesis, 2004. http://hdl.handle.net/10413/3570.

Full text

Abstract:

Vapour pressure (interchangeably referred to as atmospheric humidity) and solar radiation data are, for different reasons, difficult data to obtain in South Africa. Relative humidity measuring instruments (from which vapour pressure values can be obtained) require constant maintenance , while solar radiation can only be measured electronically. Data from both of these variables are, however, required as inputs to the Penman-Monteith equation, which has become the internationally accepted reference for the estimation of potential evaporation. It is necessary, therefore, to produce estimates of vapour pressure and solar radiation over South Africa from more common surrogates, e.g. rainfall and temperature data. Several methods of estimating vapour pressure and solar radiation from the literature are reviewed in this dissertation. Considerably greater attention is focused on models of vapour pressure than solar radiation , as less literature exists on this subject. In general, the methods involved in estimating vapour pressure tend to be relatively rudimentary. The FAO 56 documentation advises using saturated vapour pressure at minimum air temperature as an estimate of vapour pressure, yet the implicit assumptions of using this approach can fail in many circumstances, particularly in the more arid regions . It was found that monthly vapour pressure at any given location in South Africa could be estimated from geographical (invariate) data alone. It was also found that the most influential factor affecting daily vapour pressure at a given location within a given time frame (less than one month) was "air masses". Air masses proved too complicated to model from surrogate data of temperature and rainfall , however, and were thus omitted from the final model. Daily values of vapour pressure and vapour pressure deficit were estimated by holding vapour pressure for a given month constant, but varying temperature on a daily basis It was found that this method produced acceptable results for both elements throughout South Africa. The need for estimating solar radiation has existed for considerably longer than for vapour pressure. Professions other than agriculture, principally architecture and civil engineering, have long required solar radiation data/values. For this reason the art of estimating solar radiation values is better established and more models were available in the literature. Several suitable and recently developed solar radiation models, which use surrogate data (temperature and rainfall) , were identified from the literature survey. These models were then applied in situ and the results were compared with observed values. It was found that the majority of models produced similar output to one another. However, the Liu and Scott (2001) model, which is an enhancement of the Bristow and Campbell (1984) model, was found to be the best available model of those tested, particularly in the more humid locations of South Africa . Verification analyses revealed that the Liu and Scott (2001) model could be used to interpolate solar radiation where a sparse network of solar radiation measuring stations exists, e.g. in the arid locations of South Africa . The structure of the Liu and Scott (2001) model , however, prevented it from being employed in a subsequent exercise on mapping solar radiation over South Africa . For this purpose, the Hunt et al . (1998) model was employed. The estimation of two elements , vapour pressure and solar radiation , was improved upon, and the Penman-Monteith equation can thus now be more confidently applied throughout South Africa. Of these two elements, it is vapour pressure , which, because of a paucity of research to date on the subject, lends itself to expansive research in the future .
Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.

APA, Harvard, Vancouver, ISO, and other styles

39

Krasowski, Christopher B. "On the modelling of solar radiation in urban environments – applications of geomatics and climatology towards climate action in Victoria." Thesis, 2019. http://hdl.handle.net/1828/11217.

Full text

Abstract:

Modelling solar radiation data at a high spatiotemporal resolution for an urban environment can inform many different applications related to climate action, such as urban agriculture, forest, building, and renewable energy studies. However, the complexity of urban form, vastness of city-wide coverage, and general dearth of climatological information pose unique challenges doing so. To address some climate action goals related to reducing building emissions in the City of Victoria, British Columbia, Canada, applied geomatics and climatology were used to model solar radiation data suitable for informing renewable energy feasibility studies, including photovoltaic system sizing, costing, carbon offsets, and financial payback. The research presents a comprehensive review of solar radiation attenuates, as well as methods of accounting for them, specifically in urban environments. A novel methodology is derived from the review and integrates existing models, data, and tools – those typically available to a local government. Using Light Detection and Ranging (LiDAR), a solar climatology, Esri’s ArcGIS Solar Analyst tool, and Python scripting, daily insolation (kWh/m2) maps are produced for the city of Victoria. Particular attention is paid to the derivation of daily diffuse fraction from atmospheric clearness indices, as well as LiDAR classification and generation of a Digital Surface Model (DSM). Novel and significant improvements in computation time are realized through parallel processing. Model results exhibit strong correlation with empirical data and support the use of Solar Analyst for urban solar assessments when great care is taken to accurately and consistently represent model inputs and outputs integrated in a methodological approach.
Graduate

APA, Harvard, Vancouver, ISO, and other styles

40

Wissing, Jan Maik. "Analysis of Particle Precipitation and Development of the Atmospheric Ionization Module OSnabrück - AIMOS." Doctoral thesis, 2011. https://repositorium.ub.uni-osnabrueck.de/handle/urn:nbn:de:gbv:700-201108318300.

Full text

Abstract:

The goal of this thesis is to improve our knowledge on energetic particle precipitation into the Earth’s atmosphere from the thermosphere to the surface. The particles origin from the Sun or from temporarily trapped populations inside the magnetosphere. The best documented influence of solar (high-) energetic particles on the atmosphere is the Ozone depletion in high latitudes, attributed to the generation of HOx and NOx by precipitating particles (Crutzen et al., 1975; Solomon et al., 1981; Reid et al., 1991). In addition Callis et al. (1996b, 2001) and Randall et al. (2005, 2006) point out the importance of low-energetic precipitating particles of magnetospheric origin, creating NOx in the lower thermosphere, which may be transported downwards where it also contributes to Ozone depletion. The incoming particle flux is dramatically changing as a function of auroral/geomagnetical activity and in particular during solar particle events. As a result, the degree of ionization and the chemical composition of the atmosphere are substantially affected by the state of the Sun. Therefore the direct energetic or dynamical influences of ions on the upper atmosphere depend on solar variability at different time scales. Influences on chemistry have been considered so far with simplified precipitation patterns, limited energy range and restrictions to certain particle species, see e.g. Jackman et al. (2000); Sinnhuber et al. (2003b, for solar energetic protons and no spatial differentiation), and Callis et al. (1996b, 2001, for magnetospheric electrons only). A comprehensive atmospheric ionization model with spatially resolved particle precipitation including a wide energy range and all main particle species as well as a dynamic magnetosphere was missing. In the scope of this work, a 3-D precipitation model of solar and magnetospheric particles has been developed. Temporal as well as spatial ionization patterns will be discussed. Apart from that, the ionization data are used in different climate models, allowing (a) simulations of NOx and HOx formation and transport, (b) comparisons to incoherent scatter radar measurements and (c) inter-comparison of the chemistry part in different models and comparison of model results to MIPAS observations. In a bigger scope the ionization data may be used to better constrain the natural sources of climate change or consequences for atmospheric dynamics due to local temperature changes by precipitating particles and their implications for chemistry. Thus the influence of precipitating energetic particles on the composition and dynamics of the atmosphere is a challenging issue in climate modeling. The ionization data is available online and can be adopted automatically to any user specific model grid.

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Solar radiation; Atmospheric ozone'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles