Large public events, such as concerts, rallies, and festivals, impact turf health when held on natural turfgrass surfaces. The impact associated with these events is due to the placement of physical structures such as stages and seating areas and pedestrian and vehicular traffic on the turf surface. Trafficked turf protection covers, which are field covers meant to be placed directly on the turf surface where pedestrian or vehicular traffic is expected and/or equipment will be placed, can be used to minimize damage to the turf surface. Scientific data on turf response to these covers is lacking. Four cover treatments comprised of a non-covered non-trafficked control, plywood, plywood + Enkamat Plus, and white high-density polypropylene [single sided (Terratile) or double sided (Matrax)] were applied to tall fescue (Festuca arundinacea Schreb.) and effects of light intensity, duration of covering, season and soil moisture were evaluated. Growth chambers and field experiments were conducted in 2010-2011. Tissue samples were taken in growth chambers experiments every four days over the 20-day period to analyze chlorophyll (Chl a, Chl b, Chl a+b) and carotenoids (carot) under split factors of light intensity (12hr, PAR 530 μmol m-2 s-1, 5 μmol m-2 s-1) and soil moisture (50%, 75% of pot soil moisture capacity). Field trial treatment effects were observed every two days and eight days after cover removal in the spring, summer and fall and a normalized difference vegetative index (NDVI) measure was used at the conclusion of each trial period to confirm visual ratings. Covers that allowed light transmission to the canopy provided the best visual retention of percent green cover and higher contents of Chl a, Chl b, Chl a+b and carot. However, when treatments were tested under conditions that simulated low light under a concert stage (PAR 5 μmol m-2 s-1), covers performed similarly. Moderate soil moisture increased Chl b and carot content under covers. Field trials showed that plywood and plywood + Enkamat allowed for acceptable covering periods of six days in spring, four days in fall, and zero days in summer. Summer conditions shortened the number of days (8 -10) thattall fescue could be covered with Matrax and Terratile and still maintain an acceptable level of green cover. Matrax performed the best during high temperatures and did not tend to sink into the turf in saturated soil. All covers exhibited desirable qualities and limitations that should be considered for turf protection during an event. / Master of Science

Yes / The variation of solar irradiance is one of the natural forcing mechanisms of the terrestrial climate. Hence, the time-dependent solar irradiance is an important input parameter for climate modelling. The solar surface magnetic field is a powerful proxy for solar irradiance reconstruction. The analyses of data obtained with the Michelson Doppler Imager (MDI) on board the SOHO mission are therefore useful for the identification of solar surface magnetic features to be used in solar irradiance reconstruction models. However, there is still a need for automated technologies that would enable the identification of solar activity features from large databases. To achieve this we present a series of enhanced segmentation algorithms developed to detect and calculate the area coverages of specific magnetic features from MDI intensitygrams and magnetograms. These algorithms are part of the Automated Solar Activity Prediction (ASAP) tool. The segmentation algorithms allow us to identify the areas on the solar disk covered by magnetic elements inside and outside boundaries of active regions. Depending on their contrast properties, magnetic features within an active region boundary are classified as sunspot umbra and penumbra, or faculae. Outside an active region boundary magnetic elements are identified as network. We present the detailed steps involved in the segmentation process and provide the area coverages of the segmented MDI intensitygrams and magnetograms. The feature segmentation was carried out on daily intensitygrams and magnetograms from April 21, 1996 to April 11, 2011. This offers an exciting opportunity to undertake further investigations that benefit from solar features segmentations, such as solar irradiance reconstruction, which we plan to investigate in the future.

Solar photovoltaic (PV) resources are a key enabling technology in the global energy transition towards a more sustainable future. However, PV generation is highly variable due to the dynamic shading caused by clouds. To mitigate the effects of PV variability on electrical grid stability, grid operators rely on solar forecasts to proactively dispatch grid assets and balance supply and demand. To gain insights into the nature of solar variability, which is key for effective solar forecasting, this thesis presents a statistical assessment of high resolution spectral and broadband solar irradiance in Ottawa, Canada. The statistical assessment investigates the first- and second-order spectral and temporal dependencies of irradiance time series within the context of stationarity. The temporal structures indicate that solar irradiance processes are at best weakly stationary, and the implications for forecasting are discussed. The results of the statistical assessment are leveraged to develop several deterministic machine learning solar forecasting models (LSTM, XGBoost, and 1D-CNN). These models are implemented and compared in terms of computational complexity and prediction accuracy. It was found that under all sky conditions, the inclusion of spectral irradiance data improved forecasting performance compared to only using broadband irradiance. A ramp regime classification algorithm is then described, which enables the training and testing specialized ramp regime forecasting sub-models. These specialized sub-models were found to yield even greater forecasting accuracy within their respective ramp regimes, compared with the all-sky models. Further optimization and ensembling of the presented solar forecasting models is recommended for future work.

No description available.

We introduce two models to design near field reflectors in R^3 that solve an inverse problem in radiometry, taking into account the inverse square law of irradiance. The problem leads to a Monge-Ampere type inequality. The surfaces in the first model are strictly convex and require to be far from the source to avoid obstruction. In the second model, the reflectors are neither convex nor concave and do not block the rays even if they are close to the source. / Mathematics

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.

Yes / The cadence and resolution of solar images have been increasing dramatically with the launch of new spacecraft such as STEREO and SDO. This increase in data volume provides new opportunities for solar researchers, but the efficient processing and analysis of these data create new challenges. We introduce a fuzzy-based solar feature-detection system in this article. The proposed system processes SDO/AIA images using fuzzy rules to detect coronal holes and active regions. This system is fast and it can handle different size images. It is tested on six months of solar data (1 October 2010 to 31 March 2011) to generate filling factors (ratio of area of solar feature to area of rest of the solar disc) for active regions and coronal holes. These filling factors are then compared to SDO/EVE/ESP irradiance measurements. The correlation between active-region filling factors and irradiance measurements is found to be very high, which has encouraged us to design a time-series prediction system using Radial Basis Function Networks to predict ESP irradiance measurements from our generated filling factors.

Nous présentons un modèle pour l’irradiance solaire spectrale entre 200 et 400 nm. Celui-ci est une extension d’un modèle d’irradiance solaire totale basé sur la simulation de la fragmentation et l’érosion des taches qui utilise, en entrée, les positions et aires des taches observées pour chaque pas de temps d’une journée. L’émergence des taches sur la face du Soleil opposée à la Terre est simulée par une injection stochastique. Le modèle simule ensuite leur désintégration, qui produit des taches plus petites et des facules. Par la suite, l’irradiance est calculée en sommant la contribution des taches, des facules et du Soleil inactif. Les paramètres libres du modèle sont ajustés en comparant les séquences temporelles produites avec les données provenant de divers satellites s’étalant sur trois cycles d’activité. Le modèle d’irradiance spectrale, quant à lui, a été obtenu en modifiant le calcul de la contribution des taches et des facules, ainsi que celle du Soleil inactif, afin de tenir compte de leur dépendance spectrale. Le flux de la photosphère inactive est interpolé sur un spectre synthétique non magnétisé, alors que le contraste des taches est obtenu en calculant le rapport du flux provenant d’un spectre synthétique représentatif des taches et de celui provenant du spectre représentatif du Soleil inactif. Le contraste des facules est quand à lui calculé avec une procédure simple d’inversion de corps noir. Cette dernière nécessite l’utilisation d’un profil de température des facules obtenu à l’aide de modèles d’atmosphère. Les données produites avec le modèle d’irradiance spectrale sont comparées aux observations de SOLSTICE sur UARS. L’accord étant peu satisfaisant, particulièrement concernant le niveau d’irradiance minimal ainsi que l’amplitude des variations, des corrections sont appliquées sur le flux du Soleil inactif, sur le profil de température des facules, ainsi qu’à la dépendance centre-bord du contraste des facules. Enfin, un profil de température des facules est reconstruit empiriquement en maximisant l’accord avec les observations grâce à un algorithme génétique. Il est utilisé afin de reconstruire les séquences temporelles d’irradiance jusqu’en 1874 à des longueurs d’ondes d’intérêt pour la chimie et la dynamique stratosphérique. / We present a model for spectral solar irradiance between 200 and 400 nm. It is an extension of a model for total solar irradiance based on sunspots fragmentation and erosion. This model takes the observed sunspot position and area as input for every oneday time step whereas emergences on the far side of the Sun are injected stochastically. The model simulates the spot’s disintegration and fragmentation into smaller structures such as spots and faculae and produces a magnetic structures area distribution evolving with time. The model contains many free parameters controlling the spots fragmentation, the quiet Sun irradiance, etc. They are adjusted by comparing the model outputs with observations from satellites spanning approximately three activity cycles. The model for spectral irradiance is a modified version of the model for total irradiance. More precisely, the spots and faculae contrast calculation and the quiet Sun contribution are adjusted to account for their spectral dependance. First, the quiet Sun flux is interpolated on a non magnetic synthetic spectrum, while the spots contrast is calculated with the ratio of the flux from a synthetic spectrum colder than the non magnetic photosphere, and the flux from a quiet Sun spectrum. The facular brightening is calculated with a simple procedure using the black body theory. This procedure interpolates a temperature associated with the formation height of photons from faculae on a temperature profile resulting from model atmosphere calculations. The spectral irradiance time series calculated with the model are compared to data from SOLSTICE on UARS. The two data sets do not agree very well, especially when we consider the minimum irradiance level and the amplitude variations over a complete cycle. Therefore, we apply a correction on the quiet Sun level and on the facular temperature profile. Finally, using a genetic algorithm, we reconstruct an empirical facular temperature profile by maximizing the fitness with observations. We use it to reconstruct spectral irradiance time series starting in 1874 at wavelengths of interest for stratospheric chemistry and dynamics.

Nous présentons un modèle pour l’irradiance solaire spectrale entre 200 et 400 nm. Celui-ci est une extension d’un modèle d’irradiance solaire totale basé sur la simulation de la fragmentation et l’érosion des taches qui utilise, en entrée, les positions et aires des taches observées pour chaque pas de temps d’une journée. L’émergence des taches sur la face du Soleil opposée à la Terre est simulée par une injection stochastique. Le modèle simule ensuite leur désintégration, qui produit des taches plus petites et des facules. Par la suite, l’irradiance est calculée en sommant la contribution des taches, des facules et du Soleil inactif. Les paramètres libres du modèle sont ajustés en comparant les séquences temporelles produites avec les données provenant de divers satellites s’étalant sur trois cycles d’activité. Le modèle d’irradiance spectrale, quant à lui, a été obtenu en modifiant le calcul de la contribution des taches et des facules, ainsi que celle du Soleil inactif, afin de tenir compte de leur dépendance spectrale. Le flux de la photosphère inactive est interpolé sur un spectre synthétique non magnétisé, alors que le contraste des taches est obtenu en calculant le rapport du flux provenant d’un spectre synthétique représentatif des taches et de celui provenant du spectre représentatif du Soleil inactif. Le contraste des facules est quand à lui calculé avec une procédure simple d’inversion de corps noir. Cette dernière nécessite l’utilisation d’un profil de température des facules obtenu à l’aide de modèles d’atmosphère. Les données produites avec le modèle d’irradiance spectrale sont comparées aux observations de SOLSTICE sur UARS. L’accord étant peu satisfaisant, particulièrement concernant le niveau d’irradiance minimal ainsi que l’amplitude des variations, des corrections sont appliquées sur le flux du Soleil inactif, sur le profil de température des facules, ainsi qu’à la dépendance centre-bord du contraste des facules. Enfin, un profil de température des facules est reconstruit empiriquement en maximisant l’accord avec les observations grâce à un algorithme génétique. Il est utilisé afin de reconstruire les séquences temporelles d’irradiance jusqu’en 1874 à des longueurs d’ondes d’intérêt pour la chimie et la dynamique stratosphérique. / We present a model for spectral solar irradiance between 200 and 400 nm. It is an extension of a model for total solar irradiance based on sunspots fragmentation and erosion. This model takes the observed sunspot position and area as input for every oneday time step whereas emergences on the far side of the Sun are injected stochastically. The model simulates the spot’s disintegration and fragmentation into smaller structures such as spots and faculae and produces a magnetic structures area distribution evolving with time. The model contains many free parameters controlling the spots fragmentation, the quiet Sun irradiance, etc. They are adjusted by comparing the model outputs with observations from satellites spanning approximately three activity cycles. The model for spectral irradiance is a modified version of the model for total irradiance. More precisely, the spots and faculae contrast calculation and the quiet Sun contribution are adjusted to account for their spectral dependance. First, the quiet Sun flux is interpolated on a non magnetic synthetic spectrum, while the spots contrast is calculated with the ratio of the flux from a synthetic spectrum colder than the non magnetic photosphere, and the flux from a quiet Sun spectrum. The facular brightening is calculated with a simple procedure using the black body theory. This procedure interpolates a temperature associated with the formation height of photons from faculae on a temperature profile resulting from model atmosphere calculations. The spectral irradiance time series calculated with the model are compared to data from SOLSTICE on UARS. The two data sets do not agree very well, especially when we consider the minimum irradiance level and the amplitude variations over a complete cycle. Therefore, we apply a correction on the quiet Sun level and on the facular temperature profile. Finally, using a genetic algorithm, we reconstruct an empirical facular temperature profile by maximizing the fitness with observations. We use it to reconstruct spectral irradiance time series starting in 1874 at wavelengths of interest for stratospheric chemistry and dynamics.

With the increase in energy demand, and therefore, in energy generation, new high voltage direct current export links and overseas connections of large amounts of power are being introduced. These new links are subject to possible malfunction or failures, which may causea substantial frequency increase in the power system. The need of restorative measurements for over-frequencies is then necessary to regulate this probable imbalance. A new ancillary market product for frequency down-regulation is then being introduced. The Frequency Containment Reserves – Disturbances for downregulation is a service used to handle overfrequencies in the power system. The ancillary market has been historically dominated by hydro, however, with the local plans that set goals to reach 100 % renewable electricity production by the year 2040, ineluctably solar and wind will be occupying a large share of the energy generation, thus the amount of renewable resources to provide ancillary services will increase as well. Nevertheless, requirements to participate in the ancillary market are strict, and renewables face challenges such as unpredictable power generation, making forecasting tools essential for their participation. In this thesis, through the literature and research of an emerging field, the synthetic solar irradiance, an algorithm with adjusted parameters is replicated with the objective of downscaling solar irradiance presumptive-forecasts from 15-minute intervals to 1-minute intervals. An updated clear-sky model, and weather categorization method is used as input to improve the results of the synthesis. A year evaluation with a method to detect irradiance dips is used to evaluate the algorithm. The result of this study contributes with positive outputs. The introduction of this secondary tool to estimate higher resolution irradiance variability data proves to obtain, at 57 % of the point-to-point critical cases examination, an over-estimation of the measured irradiance. This, in turn, grants the actors that participate with solar power the option to adjust the bidding strategy process in the ancillary market accordingly to the output of this tool.