A study of the parameters effecting diffuse irradiance in mountainous terrain was made. Ground/location parameters of site elevation, ground albedo, elevated horizon and surface tilt were examined under the pertinent atmospheric conditions of clear, polluted, overcast , and cloudy. Measured diffuse irradiance data used for comparisons were taken from fall 1977-spring 1979 at four sites located in northern Utah. Diffuse irradiance varied with elevation according to the existing atmospheric conditions. For clear sky, diffuse irradiance decreased with elevation due t o the shorter optical pathlength, thus less scatter of the direct beam. However, with completely overcast sky, diffuse irradiance increased with elevation. The thinner cloud cover associated with higher elevations causes less adsorption of the diffuse irradiance. For partially cloudy conditions a correlation of diffuse irradiance with duration of sunshine showed curved relationships with maximum diffuse irradiance at 70 percent cloud cover. At high elevation, the curves were much steeper than at low elevation , becoming almost linear. Climatic changes in ground albedo were found to modify diffuse irradiance considerably. This occurred mainly through multiple reflection between ground and atmosphere with maximum enhancement for snow covered ground and overcas t sky. Even for clear days snow cover shifted the maximum in the annual cycle of diffuse irradiance day totals towards the spring months. A comparison of March (snow cover) and September (bare ground) diffuse irradiance values for various amounts of cloud cover showed that diffuse enhancement increased steadily with cloud amount to a maximum at overcast conditions. The effects of elevated horizon such as might be found in a mountain valley were examined through validation of a physical model describing a V-shaped valley. Comparisons between calculated and measured diffuse irradiance showed excellent results for clear days during winter, spring, and summer. The ratio of measured diffuse irradiance on a south facing sao tilt to that on the horizontal was plotted against duration of sunshine for different seasons. For clear days the Sao tilt enhanced diffuse irradiance values as much as two times the horizontal values during winter while during summer sao values dropped to .8 of the horizontal values. For overcast days the ratio varied from 1.0-0.3 for winter and summer, respectively. A model predicting diffuse irradiance on a tilted surface for clear day was developed and validated using measured data. A good comparison is shown for spring and fall days using high and low elevation data.

Firstly, this dissertation proposes a new characterization and classification method for daily sky conditions by using the daily sky clearness index (KD) and the daily probability of persistence (POP-KD) that can be derived from ground-based irradiance measurement data. Quality of daily solar irradiance is characterized by a newly proposed parameter, POP-KD. This characterized daily quality is varying and uncertain at the middle level of the quantity, but high and more certain at very high and low quantity levels. In addition, the proposed characterization method shows interesting results for KD and POP-KD: a statistical consistency for multiple years and similarity for their seasonal trends. The classification results also indicate an existence of dominant classes, and transitions between the dominant classes are significant for all locations. This dissertation also generates annual synthetic sequences of KD and POP-KD using a Markov approach. The generated sequences show statistical similarities with observed sequences. Secondly, this dissertation proposes methodologies to estimate day-ahead solar irradiance using the National Weather Service (NWS) sky cover forecast. For model development, this paper splits up a direct estimation process from the sky cover forecast to solar irradiance into two stages: forecast verification and cloud-to-irradiance conversion. Uncertainty for each stage and for the overall estimation process is quantified. NWS forecast uncertainty (about 20%) is identified as the main source of uncertainty for the overall process. In addition, verification of the sky cover forecast shows approximately 20% overestimated bias at days with a high irradiance level. Thus, the NWS sky cover forecast needs to be adjusted based on the type of day. This dissertation also proposes a conversion equation relating daily quantity of cloud information and daily quantity of solar irradiance. The proposed conversion equation achieves accuracy with simplicity. Five day-ahead solar irradiance quantity estimation methods are proposed in this dissertation. The proposed methods incorporate different schemes for dealing with the bias discovered in the cloud forecast. The observed data are regularly found within the 95% confidence intervals of the estimated values. Estimation results demonstrate the effectiveness of the conditional adjustment schemes at different irradiance levels. Lastly, this dissertation proposes a methodology to estimate day-ahead solar irradiance using fluctuation information of the NWS sky cover forecast. POP-KD was used as a parameter for the quality of daily solar irradiance. POP-KD efficiently represents the quality of daily solar irradiance. In addition, POP-KD indicates the probability that solar irradiance variability is within the ramp rates of common generators in power systems at a certain photovoltaic penetration level. This dissertation also proposes a new equation for the conversion from cloud fluctuation information to daily quality of surface solar irradiance. The proposed equation achieves accuracy. The proposed day-ahead solar irradiance quality estimation method is based on fluctuation information provided by the NWS sky cover forecast. This method uses a normalization approach to relate fluctuation of cloud forecast and fluctuation of cloud observation. The observed data are regularly found within the 95% CIs of the estimated values. / Ph. D.

In recent years, different renewable energy sources have been on the rise. Among these, solar power has shown great potential in both small and big scale. Since solar irradiance is the main input for solar power systems, it is of great importance to examine how much of the solar irradiance actually reaches a certain location, and how much of the total solar irradiance consists of direct (beam), diffuse and reflected irradiance. This is usually done with expensive measurement meters, such as pyranometers and pyrheliometers. In this thesis, incident solar irradiance data from a cheap sensor network is analyzed, a new proposed model for estimating beam and diffuse fraction is examined and the results are compared to another estimation model, namely Erbs model. The comparison between the two models shows high correlation for beam irradiance, regardless of weather conditions, whereas the correlation for diffuse irradiance shows a highly varying result, much dependent on the weather conditions. It is difficult to motivate how well the proposed model is performing on a broader scale, since the study is limited to a specific area during a short period of time.

xv, 165 p. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / The amount of solar radiation at the earth's surface is modulated by fluctuations in aerosol density and cloud optical depth--two uncertain factors in climate change studies. The University of Oregon Solar Radiation Monitoring Lab has collected five-minute resolution surface shortwave irradiance measurements at three sites in Oregon since 1980 or earlier. Direct normal surface solar irradiance has increased 4-5% per decade (8-11 W/m 2 per decade) at these three sites since 1980 (1979 in Eugene). Total solar irradiance has likewise increased by 1-2% per decade (2-3 W/m 2 per decade). This unusually long direct normal time series was used to examine the causes of trends because of its high sensitivity to scattering and high instrumental accuracy. The strongest factor causing direct normal irradiance trends was found to be the high stratospheric aerosol concentrations after the volcanic eruptions of El Chichà à à à ³n (1982) and Mt. Pinatubo (1991). Removing the four years most impacted by each volcanic eruption (1982-1985 and 1991-1994) reduces the trend in annual average direct normal irradiance by 20-55%, depending on the site. All measurement sites show low irradiance values before the volcanic eruption of El Chichà à à à ³n in 1982 compared to later periods of relatively low volcanic aerosols (1989- 1990, and 2000-2007). These low values are visible both in all-sky and clear-sky monthly averages, suggesting high aerosol loads as a likely cause. Clear-sky direct normal irradiance measurements from high solar zenith angles (6575à à à à °) are analyzed to test the hypothesis that the increase in irradiance comes from a reduction of anthropogenic aerosols since the late 1980s. No change in anthropogenic aerosols between 1987 and 2007 is detectable within the noise of the data. Even after removing the four years most heavily impacted by volcanic eruptions, the continued reduction of volcanic aerosol loads causes over half of the clear-sky direct normal irradiance increase since 1987. The remaining increase could be accounted for by a 20-year decrease in 550 nm aerosol optical depth of .005 à à à à ± .005, or 6% à à à à ± 6%, but considerable statistical uncertainty exists. / Adviser: Gregory Bothun

Due essentially to the difficulties associated with obtaining explicit forms of stationary marginal distributions of non-linear stationary processes, appropriate characterizations of such processes are worked upon little. After discussing an elaborate motivation behind this thesis and presenting preliminaries in Chapter 1, we characterize, in Chapter 2, the stationary marginal distributions of certain non-linear multivariate stationary processes. To do so, we show that the stationary marginal distributions of these processes belong to specific skew-distribution families, and for a given skew-distribution from the corresponding family, a process, with stationary marginal distribution identical to that given skew-distribution, can be found. While conventional time series analysis greatly depends on the assumption of stationarity, measurements taken from many physical systems, which consist of both periodicity and randomness, often exhibit cyclostationarity (i.e., a periodic structure in their first- and second-order moments). Identifying the hourly global horizontal irradiances (GHIs), collected at a solar monitoring station of Saudi Arabia, as a cyclostationary process and considering the significant impact of that on the energy production in Saudi Arabia, Chapter 3 provides a temporal model of GHIs. Chapter 4 extends the analysis to a spatio-temporal cyclostationary modeling of 45 different solar monitoring stations of the Kingdom. Both the proposed models are shown to produce better forecasts, more realistic simulations, and reliable photovoltaic power estimates in comparison to a classical model that fails to recognize the GHI data as cyclostationary. Chapter 5 extends the notion of cyclostationarity to a novel and flexible class of processes, coined evolving period and amplitude cyclostationary (EPACS) processes, that allows periods and amplitudes of the mean and covariance functions to evolve and, therefore, accommodates a much larger class of processes than the cyclostationary processes. Thereafter, we investigate its properties, provide methodologies for statistical inference, and illustrate the presented methods using a simulation study and a real data example, from the heavens, of the magnitudes of the light emitted from the variable star R Hydrae. Finally, Chapter 6 summarizes the findings of the thesis and discusses its significance and possible future extensions.

This study addresses the availability of total solar irradiance at the earth's surface during varying weather conditions . Two years of irradiance and meteorological data were collected at mountain and valley sites along 40° North latitude in the Rocky Mountains of Utah and Colorado. Generalized cases of recurring seasonal weather episodes and the associated t o t al irradiance a re identified and discussed , including local mesoscale phenomena (orographic clouds , valley fog, etc.) unique to mountainous regions . The generalized cases can be useful in long- range energy assessment planning. The east and west slopes of the Rocky Mountains are shown to have similar annual average solar energy potential , however the seasonal differences reveal unique climates which require different considerations for each slope. Short -term relationships between cloudiness and t o t al irradiance are developed for the mountainous region, providing a tool for forecasting solar irradiance using a cloudiness forecast. Total irradiance is shown to correlate much better to opaque sky cover than co total cloud cover . The relationships on the east and west slopes are similar , however greater variations a re observed with elevation between the moun t ain and valley sites . Short- term forecasting of irradiance is found to be limited due t o unreliable cloudiness fore-casting techniques , tho ugh satellite imagery trajectories are more reliable than numerical methods.

On-board the International Space Station (ISS), the Remote Atmospheric and Ionospheric Detection System (RAIDS) is a suite of limb-scanning monitors taking measurements from the extreme ultraviolet (EUV) to the near infrared (NIR). A single-scattering Rayleigh model is developed to eliminate the scattered brightness below 90 km and an inversion technique is applied on limb-scanned radiance profiles at 236.5 nm, NO (0,1) gamma band. The ISS orbit allows observations from 7:00 to 16:00 local hours over a one-month period from mid-June to mid-July of 2010 and observation of the local-time variation of NO abundance in the lower thermosphere is derived. The uniquely stable solar activity during 2010 allows the local time variation of NO to be observed with limited influence of solar variability. The comparison with a 1D model shows good agreement at altitude above 120 km, suggesting that most of the local time variation of NO is due to solar illumination, radiation, chemistry, and vertical diffusion. Solar soft X-ray is the major driver of the variability observed in the ionospheric and thermospheric constituents at the equatorial region. Over the years measurements in these wavelengths are scarce and discrepancies lie among the existing data. The Solar Aspect Monitor (SAM) is a pinhole camera on the Extreme-ultraviolet Variability Experiment (EVE) flying on the Solar Dynamics Observatory (SDO). Every 10 seconds SAM projects the solar disk onto the CCD through a metallic filter designed to allow only solar photons shortward of 7 nm to pass. Contamination from energetic particles and out-of-band irradiance is, however, present. The broadband (BB) technique is developed for isolating the 0.1 to 7 nm integrated irradiance to produce broadband irradiance. The results agree with the zeroth-order product from the EUV SpectroPhotometer (ESP) with 25% regardless of solar activity level. Active regions in the solar atmosphere are tracked by the Apertural Progression Procedure for Light Estimate (APPLE). The photon event detection (PED) algorithm takes both BB and APPLE results as prior information to extract in-band photons. Applications of the PED products, including solar feature studies and spectral resolved irradiance, are demonstrated. / Ph. D.

Modeling of solar irradiance for lunar base locations Abstract An incident radiation is an essential factor for a discovery of a place suitable for building a lunar base. This thesis presents a new approach for modeling of solar irradiance in an arbitrary lunar location at selected time. Shadowing by surrounding terrain is calculated by spatial intersection between lines of illumination and digital terrain model. Model also takes variable distance between Moon and Sun and areal representation of the Sun into account. In this thesis a new geometrical procedure for calculation of reflected irradiance is designed. The resulting model is implemented within ArcGIS software as an executable script, which utilizes the freely available data from Lunar Reconnaissance Orbiter as an input. Key words: Moon, solar irradiance, geoinformatic modelling, scripting

Cette thèse a pour objectif d'apporter un regard nouveau sur les principales caractéristiques physiques du Soleil. Avant le développement de l'astrophysique, l'étude d'un astre concernait surtout ses propriétés géométriques. La mesure précise du diamètre du Soleil a été entreprise dès l'antiquité et représente un des plus vieux problèmes en astrophysique. Une partie de cette thèse est consacrée à l'étude du diamètre solaire et de ses variations au cours du temps. Un des objectifs est de déterminer si le diamètre du Soleil varie en fonction de l'activité solaire. Les données acquises par les instruments de la mission PICARD ont été utilisées afin d'essayer de répondre à cette question. Cette thèse porte aussi sur la détermination absolue de l'aplatissement solaire et de ses variations au cours du cycle 24. Cette étude s'est basée sur l'exploitation des mesures acquises par deux télescopes spatiaux (PICARD/SODISM et SDO/HMI). Les mesures de l'aplatissement solaire sont importantes et permettent de valider les hypothèses physiques mises en œuvre dans les modèles du Soleil. Cette thèse consiste aussi à déterminer la valeur absolue de l'éclairement solaire total et de sa variabilité au cours du temps. L'éclairement solaire total représente une entrée essentielle pour tous les modèles climatiques. Sa détermination précise est donc fondamentale. La valeur absolue de l'éclairement solaire total a été obtenue à partir des mesures réalisées par le radiomètre PICARD/SOVAP. Le dernier chapitre de cette thèse est dédié à l'étude de l'éclairement solaire dans l'ultraviolet et de ses variations au cours du cycle 24. Cette étude s'appuie sur les mesures réalisées par le spectromètre SOLAR/SOSLPEC à bord de la station spatiale internationale. La variabilité du rayonnement ultraviolet au cours d'un cycle solaire (environ 10% à 200 nm) est beaucoup plus élevée que celle de l'éclairement solaire total (environ 0.1%). La détermination précise de la variabilité ultraviolet est donc très importante. Il est aussi de plus en plus évident que les variations de l'éclairement solaire dans l'ultraviolet jouent un rôle significatif au niveau de la chimie de l'atmosphère et du climat de la Terre. Les résultats obtenus au cours de cette thèse montrent l'intérêt de réaliser des mesures précises dans l'ultraviolet au cours d'un cycle solaire de 11 ans. / This thesis aims to highlight a new vision on the main physical characteristics of the Sun. Before the development of astrophysics, the study of a star mainly concerned its geometrical properties. The accurate measurement of the solar diameter was carried out since the antiquity and represents one of the oldest problems in astrophysics. Part of this thesis is devoted to the study of the solar diameter and its variation over time. One of the objectives is to determine whether the diameter of the Sun varies with the solar activity. Data acquired by the PICARD mission instruments were used to try to answer this question. This thesis also deals with the absolute determination of the solar oblateness and its variation during the cycle 24. This study was based on the use of the measurements acquired by two space-based telescopes (PICARD/SODISM and SDO/HMI). The solar oblateness measurements are important and allow to validate the physical hypotheses implemented in the solar models. This thesis also consists to determine the absolute value of the total solar irradiance and its variability over time. The total solar irradiance is an essential parameter for all climate models. Its accurate determination is therefore fundamental. The absolute value of the total solar irradiance was obtained from the measurements carried out by the PICARD/SOVAP radiometer during the solar cycle 24. The last chapter of this thesis is devoted to the study of the solar irradiance in the ultraviolet and its variation during the solar cycle 24. This study is based on the measurements carried out by the SOLAR/SOSLPEC spectrometer on board the International Space Station. The variations of the ultraviolet radiation during a solar cycle (10% at 200 nm for a strong solar cycle) are much higher than the variations of the total solar irradiance (0.1%). The accurate determination of the ultraviolet solar irradiance is therefore very important. It is also increasingly evident that the variations of the solar irradiance in the ultraviolet play a significant role in the chemistry of the Earth's atmosphere and climate. The results obtained during this thesis show the interests to perform accurate measurements in the ultraviolet during a solar cycle of about 11 years. Through this work, we bring a new perspective with respect to the absolute value of the main solar parameters.

This thesis is focused on the aerosols and clouds optical properties and the effects that these parameters have on the solar radiation transfer in the atmosphere. The first chapter provides a brief description of the basic concepts of radiative transfer. The radiative transfer theory is described, along with various approximations, used to address specific atmospheric transfer problems. The atmospheric constituents, which are of interest of this thesis, aerosols and clouds, are described, in terms of their types and radiative properties and the main aspects of the scattering and absorption that they induce on the solar radiation, are provided. The second chapter provides a description of the networks, models and satellite instruments, whose data were used in this thesis, along with a description of the radiative transfer model, used for the simulations. Chapter three focuses on the aerosol optical properties in the ultraviolet and visible wavelength ranges, in the Mediterranean. Three datasets, from ground-based stations, global aerosol models and satellite instruments, are used to simulate the corresponding irradiances in the UV and VIS, in eight stations in the Mediterranean basin. Data from AERONET, AeroCom and MODIS are used and the differences on the modeled irradiances, which arise from the different aerosol optical properties provided by each dataset, are examined. The irradiance simulations are performed with the libRadtran radiative transfer model. The MODIS aerosol optical depth climatology shows better agreement with AERONET data. The highest difference in the monthly average values is equal to 0.09 at 550nm, while the differences between the AERONET and the AeroCom climatologies reach 0.25 and 0.15 in the UV and VIS wavelengths respectively. As a result, the AERONET modeled VIS and UV irradiances are closer to MODIS, with the absolute differences in average values reaching 6%, while absolute differences with AeroCom irradiances can reach up to 12%. The differences are higher in areas affected by desert dust aerosols. In chapter four, the aerosol direct effect on the UV solar irradiance, is examined, at a typical West European site. Measurements from a Brewer instrument, operating at the site, are used, along with model simulations, provided from libRadtran, to estimate the aerosol forcing efficiency in the 300-360 nm spectral region and in the UV-B region of 300-315nm. Instrument measurements and model calculations are subsequently used to derive the aerosol single scattering albedo at low UV-A and at UV-B wavelengths. In the 300-360 nm spectral region, the highest values were revealed at 30o (-6.9 ± 0.9 W/m2), while at 60o the RFE was almost 2.5 times lower (-2.7 ±0.1 W/m2). In the UV-B region (300-315nm), the RFE value at 60o and 30o was estimated to be equal to -0.069 ±0.005 W/m2 and -0.35 ±0.04 W/m2, respectively. The estimated monthly averages of the Brewer single scattering albedo at 320 nm are in very close agreement (within ±0.01) with measurements at 440nm from a collocated CIMEL sunphotometer. Chapter five focuses on the aerosol effect on the Direct Normal Irradiance, in the area of Europe. Data from the MODIS satellite instrument, AERONET network and model simulations with SBDART, are used to calculate the daily amount of Direct Normal Irradiance received in the European continent, with a spatial resolution of 1°x1°, for a 13-year period. The clear-sky aerosol radiative forcing is calculated and possible variations in the received Direct Normal Irradiance, during the 13-year studied period, are examined. The clear-sky aerosol radiative forcing on Direct Normal Irradiance is high in areas influenced by desert dust and intense anthropogenic activities, such as the Mediterranean basin and the Po Valley in Italy. In May, the attenuation from aerosols, over these areas, can reach values up to 35% and 35-45%, which corresponds to 4 and 4.5-6 kWh/m2 per day, respectively. The Direct Normal Irradiance received, seems to have increased during the recent period, due to the decreasing trend of aerosol load, over many parts of Europe. The largest increases are around 6 to 12%, which correspond to an amount of 0.5 to 1.25 more kWh/m2 received per day. Finally, chapter six focuses on the retrieval of solar irradiance on the ground, based on satellite-derived cloud data. The SEVIRI instrument, onboard the MSG satellites, is used to provide data regarding the cloud modification factor. These data are used, along with model simulations, performed with libRadtran, to derive the global solar irradiance incident on a horizontal surface, a surface with a tilted orientation and the direct normal irradiance. The study focuses on the area of Greece and the work is part of the Hellenic Network for Solar Energy, developed to support solar energy applications. The daily amount of solar energy, as well as the monthly and annual sums, are estimated, during an 11-year period and a monthly climatology is derived. Results are compared with measurements from various ground stations in Greece. Comparison shows a general good agreement between satellite and stations data, with the highest differences occurring in cases of broken cloud conditions or very thick clouds. Solar energy collected from surfaces under tilted orientations can provide 15-25 % higher amounts than horizontal surfaces. In Greece, the highest collected monthly solar energy values are found during summer months, in Southern Peloponnese, Crete and the Cyclades islands, and exceed 250 kWh/m2. / Η παρούσα διατριβή ασχολείται με τις οπτικές ιδιότητες των αιωρούμενων σωματιδίων και των νεφών και τις επιδράσεις που αυτές έχουν στη διάδοση της ηλιακής ακτινοβολίας στην ατμόσφαιρα. Το πρώτο κεφάλαιο παρέχει μια σύντομη περιγραφή των βασικών αρχών που διέπουν τη διάδοση της ηλιακής ακτινοβολίας. Η θεωρία της διάδοσης της ακτινοβολίας περιγράφεται, μαζί με διάφορες προσεγγίσεις, που χρησιμοποιούνται για τη λύση συγκεκριμένων προβλημάτων στις ατμοσφαιρικές επιστήμες. Τα συστατικά της ατμόσφαιρας, που είναι άμεσου ενδιαφέροντος σε αυτήν τη διατριβή, τα αιωρούμενα σωματίδια και τα νέφη, περιγράφονται, με βάση τους τύπους τους και τις οπτικές τους ιδιότητες, ενώ περιγράφονται ακόμα οι βασικές αρχές της σκέδασης και της απορρόφησης, μέσω των οποίων επηρρεάζουν τη διάδοση της ηλιακής ακτινοβολίας. Το δεύτερο κεφάλαιο παρέχει μια περιγραφή των επίγειων δικτύων, μοντέλων και δορυφορικών οργάνων, των οποίων τα δεδομένα χρησιμοποιήθηκαν, για τη διεκπαιρέωση αυτής της διατριβής, μαζί με την περιγραφή του μοντέλου διάδοσης της ακτινοβολίας, που χρησιμοποιήθηκε για τους θεωρητικούς υπολογισμούς. Το τρίτο κεφάλαιο επικεντρώνεται στις οπτικές ιδιότητες των αιωρούμενων σωματιδίων, στο υπεριώδες και ορατό κομμάτι του ηλεκτρομαγνητικού φάσματος, στην Μεσόγειο. Τρεις ξεχωριστές βάσεις δεδομένων, από επίγειους σταθμούς, μοντέλα και δορυφορικά όργανα, χρησιμοποιούνται για τον υπολογισμό της ακτινοβολίας στο υπεριώδες και ορατό, σε οχτώ σταθμούς στην περιοχή της Μεσογείου. Χρησιμοποιούνται δεδομένα από το AERONET, το AeroCom και το MODIS και μελετούνται οι διαφορές στις υπολογιζόμενες, από το μοντέλο, ακτινοβολίες, οι οποίες προκύπτουν από τις διαφορές στις οπτικές ιδιότητες των αιωρούμενων σωματιδίων, που παρέχονται από κάθε βάση δεδομένων. Οι ακτινοβολίες υπολογίζονται με το μοντέλο διάδοσης ακτινοβολίας libRadtran. Τα δεδομένα του MODIS βρίσκονται σε καλύτερη συμφωνία με αυτά του AERONET, με τη μέγιστη διαφορά στο οπτικό βάθος, στα 550 nm, να είναι ίση με 0.09, ενώ οι αντίστοιχες διαφορές με το AeroCom υπολογίζονται στα 0.25 και 0.15, για το υπεριώδες και ορατό αντίστοιχα. Ως αποτέλεσμα, οι απόλυτες διαφορές στις υπολογιζόμενες ακτινοβολίες, μεταξύ AERONET και MODIS υπολογίζονται γύρω στο 6%, ενώ αυτές που αφορούν την κλιματολογία AeroCom φτάνουν το 12%. Οι μεγαλύτερες διαφορές αφορούν περιοχές που επηρεάζονται από σωματίδια ερημικής σκόνης. Στο τέταρτο κεφάλαιο, η άμεση επίδραση των αιωρούμενων σωματιδίων, στην υπεριώδη ακτινοβολία, μελετάται, για μια τυπική περιοχή της Δυτικής Ευρώπης. Μετρήσεις από ένα όργανο Brewer, που λειτουργεί στην περιοχή και θεωρητικοί υπολογισμοί με το μοντέλο libRadtran, χρησιμοποιούνται για τον υπολογισμό της ικανότητας κλιματικού εξαναγκασμού των αιωρούμενων σωματιδίων, στο φάσμα 300-360 nm και στο UV-B φάσμα των 300-315nm. Μετρήσεις από το όργανο και θεωρητικοί υπολογισμοί, χρησιμοποιούνται στη συνέχεια για τον υπολογισμό της ανακλαστικότητας μεμονωμένης σκέδασης των αιωρούμενων σωματιδίων, σε χαμηλά UV-A και σε UV-B μήκη κύματος. Στο φάσμα 300-360 nm, οι μεγαλύτερες τιμές της ικανότητας κλιματικού εξαναγκασμού, παρατηρούνται στις 30o (-6.9 ± 0.9 W/m2), ενώ στις 60o οι τιμές είναι σχεδόν 2.5 φορές χαμηλότερες (-2.7 ±0.1 W/m2). Στο UV-B κομμάτι του φάσματος (300-315nm), οι αντίστοιχες τιμές στις 60o και 30o υπολογίζονται ίσες με -0.069 ±0.005 W/m2 και -0.35 ±0.04 W/m2. Συγκρίνοντας τις τιμές που προκύπτουν για την ανακλαστικότητα μεμονωμένης σκέδασης στα 320 nm, με αυτές από το γειτονικό CIMEL στα 440 nm, προκύπτει πολύ καλή συμφωνία (±0.01). Το πέμπτο κεφάλαιο, επικεντρώνεται στην επίδραση των αιωρούμενων σωματιδίων στην άμεση ηλιακή ακτινοβολία, σε επίπεδο κάθετο στην κατεύθυνση της ακτινοβολίας, στην περιοχή της Ευρώπης. Δεδομένα από το MODIS, το AERONET και θεωρητικοί υπολογισμοί με το μοντέλο SBDART, χρησιμοποιούνται για τον υπολογισμό της ημερήσιας ποσότητας άμεσης ηλιακής ακτινοβολίας, στην Ευρώπη, με χωρική ανάλυση 1°x1° για μια χρονική περίοδο 13 ετών. Ο κλιματικός εξαναγκασμός, υπό ανέφελο ουρανό, των αιωρούμενων σωματιδίων και πιθανές μεταβολές στην ληφθείσα άμεση ακτινοβολία κατά τη διάρκεια αυτής της περιόδου, μελετούνται. Οι επιδράσεις των αιωρούμενων σωματιδίων είναι σημαντικές σε περιοχές που επηρεάζονται από σωματίδια ερημικής σκόνης και περιοχές με έντονη ανθρωπογενή δραστηριότητα, όπως η Μεσόγειος και η κοιλάδα του Πάδου στην Ιταλία. Σε αυτές τις περιοχές η μείωση της ακτινοβολίας, λόγω αιωρούμενων σωματιδίων, φτάνει, το Μάιο, το 35% και 35-45%, που αντιστοιχεί σε 4 και 4.5-6 kWh/m2 την ημέρα. Η ληφθείσα άμεση ακτινοβολία έχει αυξηθεί κατά τα τελευταία χρόνια, λόγω ελάττωσης της συγκέντρωσης των αιωρούμενων σωματιδίων σε πολλά μέρη της Ευρώπης. Οι μεγαλύτερες αυξήσεις κυμαίνονται μεταξύ 6 και 12%, ποσοστό που αντιστοιχεί σε 0.5 με 1.25 kWh/m2 την ημέρα. Στο έκτο κεφάλαιο, αυτής της διατριβής, μελετάται ο υπολογισμός της ηλιακής ακτινοβολίας στο έδαφος, χρησιμοποιώντας δορυφορικά δεδομένα για την επίδραση των νεφών. Το όργανο SEVIRI, στους δορυφόρους MSG, χρησιμοποιείται για την παροχή δεδομένων σχετικά με το συντελεστή επίδρασης των νεφών. Τα δεδομένα αυτά, μαζί με θεωρητικούς υπολογισμούς με το μοντέλο libRadtran, χρησιμοποιούνται για τον υπολογισμό της ολικής ηλιακής ακτινοβολίας, σε οριζόντια επιφάνεια και σε επιφάνεια υπό κλίση, καθώς και τον υπολογισμό της άμεσης συνιστώσας σε επιφάνεια κάθετη στη διεύθυνση της ακτινοβολίας. Η μελέτη πραγματοποιείται για της περιοχή της Ελλάδας και αποτελεί κομμάτι του Ελληνικού Δικτύου Ηλιακής Ενέργειας, που έχει αναπτυχθεί για την υποστήριξη εφαρμογών και συστημάτων ηλιακής ενέργειας. Υπολογίζονται οι ημερήσιες ποσότητες ακτινοβολίας, οι μηνιαίες και οι ετήσιες τιμές, για μια περίοδο 11 ετών, καθώς και η μηνιαία κλιματολογία που προκύπτει για αυτήν την περίοδο. Η σύγκριση των αποτελεσμάτων με μετρήσεις από επίγειους σταθμούς, δίνει πολύ καλή συμφωνία, ενώ οι μεγαλύτερες διαφορές παρατηρούνται σε περιπτώσεις πολύ πυκνών νεφών. Η ηλιακή ακτινοβολία που συλλέγεται σε κεκλιμένη επιφάνεια, παρέχει 15-25 % μεγαλύτερα ποσά, σε σχέση με αυτήν που παρέχουν οριζόντιες επιφάνειες συλλογής. Στην Ελλάδα, τα μεγαλύτερα μηνιαία ποσά ηλιακής ενέργειας, παρατηρούνται κατά τους θερινούς μήνες, στη Νότια Πελοπόννησο, την Κρήτη και τις Κυκλάδες και ξεπερνούν τις 250 kWh/m2.