The main objectives of this study were to develop the indicatri es of reflected solar radiation from different natural surfaces and to show comparisons between values sensed in space of emergent radiation to ground values obtained from accounting for anisotropic reflection and estimating the effect of the intervening atmosphere. Thus, this study demonstrated that a prior knowledge of the angular distribution of reflected radiation allows determining the true hemispherical reflected radiation from a narrow field of view instrument such as found on a flying platform. Measurements for determining the indicatrices were made from a tower-mounted Nimbus MRIR and, in one case, with a hand-held TIROS five-channel radiometer. Anisotropy of reflected radiation was found for all surfaces examined and increased with decreasing solar angle. Different surfaces showed different degrees and patterns of fonvard and backscatter. A clearly defined anti-solar point was found for plowed field, various agricultural crops and vegetated desert surfaces, while snow, the Alkali Flats, and Bonneville Salt Flats showed a broad pattern of backscatter. As a consequence of surfaces exhibiting well-defined antisolar points the anisotropic correction factors relating normal reflectances to 2π reflected values were less than 100 percent for solar angles greater than approximately 60°. All surfaces examined showed anisotropic correction factors increasing with decreasing solar angles. The albedo over the White Sands dune field decreased with decreasing solar angles due to large shadow patterns which are produced at low solar angles. The sand dunes values were derived from aircraft measurements. Comparisons were made between estimated emergent radiation from the top of the earth 's atmosphere accounting for anisotropy of the ground reflection pattern and estimates of atmospheric attenuation to values of reflected radiation obtained from the MSS subsystem of the ERTS program for the lava beds region and White Sands area in New Mexico. Also comparisons were shown between the estimated emergent radiation from the earth's surface for the same features and spectral bands to the values sensed in space. Under high albedo conditions as found in the White Sands area there was a decrease in emergent radiation to space while with low surface albedo, such as the lava beds region, the extra-terrestrial radiation increased from the ground values.

The black colour of an asphalt pavement causes it to reach very high temperatures throughout the summer months. Asphalt binder is a temperature dependent material, so these high temperatures can result in damage to the road surface. This report explores the use of light coloured surface coatings to decrease the temperature of an asphalt pavement. A field testing method was developed to compare the effect of several surface materials on temperature. To support this field test, a method was developed to characterize the surface colour (albedo) through the use of a simple light meter. As well, the durability of the surface coatings applied to asphalt pavement surfaces was examined using the Wet Track Abrasion Test, and methods for further testing were suggested. A numerical model was developed in Abaqus to predict the temperature effects based on the surface colour and climate conditions. This model can be used to predict the temperature in an asphalt concrete pavement at the surface and throughout the depth of the pavement. Two versions of this model were created: A complete model, which is used when all climate data is available, and a simplified model, which uses estimated values to replace any data that is not available The temperature difference between white and black painted asphalt concrete surfaces was found to be as much as 17C. Using light coloured surfaces with albedo values in the range of 0.2 to 0.3 yielded a temperature decrease of approximately 7 to 10C as compared to a black painted surface. Microclimate effects were found to be significant; wind speed can drastically affect the temperature of a pavement. The use of hydrated lime in conjunction with a polymer modified asphalt surface course yielded good results for both temperature reduction and durability. It should be considered for future work. / Thesis / Master of Applied Science (MASc)

<p> The importance of snow surface albedo has been recorded by many authors. Techniques have been attempted with less than favorable results by D.E. Petzold (1977). This paper investigates the methods proposed by Petzold and offers alternative methods of albedo estimations using polar, sub-polar and continental stations as data sources. </p> / Thesis / Bachelor of Arts (BA)

Global Climate Models (GCMs) are indispensable tools for modeling climate change projections. Due to approximations, errors are introduced in the GCM computations of atmospheric radiation. The existing methodologies for the comparison of the GCM-computed shortwave fluxes (SWF) exiting the top of the atmosphere (TOA) against satellite observations do not separate the model errors in terms of the atmospheric and surface components. A new methodology has been developed for estimating the GCM systematic errors in the SWF at the TOA under clear-sky (CS) conditions. The new methodology is based on physical principles and utilizes in-situ measurements of SWF at the surface. This error adjustment methodology (EAM) has been validated by comparing GCM results against satellite measurements from the Clouds and the Earth’s Radiant Energy System (CERES) mission. The EAM was implemented in an error estimation model for solar radiation (EEMSR), and then applied to examine the hypothesis that the Community Climate System Model (CCSM), one of the most widely used GCMs, was deficient in representing the annual phenology of vegetation in many areas, and that satellite measurements of vegetation characteristics offered the means to rectify the problem. The CCSM computed monthly climatologies of TOA-CS-SWF were compared to the CERES climatology. The incorporation of satellite-derived land surface parameters improved the TOA SWF in many regions. However, for more meaningful interpretations of the comparisons, it was necessary to account for the uncertainties arising from the radiation calculations of CCSM. In-situ measurements from two sites were used by EMBC to relate the observations and model estimates via a predictive equation to derive the errors in TOA CS-SWF for monthly climatologies. The model climatologies were adjusted using the computed error and then compared to CERES climatology at the two sites. The new results showed that at one of the sites, CCSM consistently overestimated the atmospheric transmissivity whereas at the other site the CCSM overestimated during the spring, summer and early fall and underestimated during late fall and winter. The bias adjustment using the EMBC helped determine more clearly that at the two sites the utilization of satellite-derived land surface parameters improved the TOA CS-SWF.

No description available.

A computer program was written to calculate snow albedos for the months of January, March, and May in western Canada. Snow depth as well as water equivalent depth data was obtained from snow cover records and climatic maps. It was found that for the months of January and March, the snow depths were all greater than 10 cm and so the snow albedo was not a function of the surface type rather only the snow cover. For May, however, snow depths of less than 10 cm were obtained and the albedo became a function of both the water equivalent as well as surface type. The method of data collection is criticized primarily because of the instances of measurements and methods of measurement. Also, the equation in which the snow albedo is calculated is criticized because it only takes into consideration snow depth and not other important factors such as snow age density and crystal structure. However, age, density, and crystal structure are difficult measures to obtain data for on a large scale typical of GCMs. Good comparisons are made with the snow albedo values of forested sites obtained in this study with those in the literature. / Thesis / Bachelor of Science (BSc)

Humans have extensively altered terrestrial surfaces through land-use and land-cover change. This change has resulted in increased food, fiber, fuel, and wood that is provisioned by ecosystems to support the human population. Unfortunately, the change has also altered climate through carbon emissions and changes in the surface energy balance. Consequently, maximizing both the provisioning and climate regulation services provided by terrestrial ecosystems is a grand challenge facing a growing global population living in a changing climate. The planting of pine forests for timber and carbon storage and switchgrass fields for bioenergy are two land-cover types that can potentially be used for climate mitigation. Importantly, both are highly productive systems representing contrasts in albedo (grass are brighter than pines) and vegetation height (pines are taller than the grass) along with unknown differences in carbon and water balance that influence local to global climate. Here I use eddy-covariance data to investigate how a transition from a perennial bioenergy crop (switchgrass) to a planted pine plantation alters the local surface temperature, global carbon dioxide concentrations, and global energy balance. First, I found that switchgrass and pine ecosystems have very similar local surface temperatures, especially during the grass growing season. After the switchgrass is harvested, surface temperature in the pine forest is much lower than switchgrass because no vegetation is present to facilitate the evaporation of water. The surface temperature in a bare-ground system (a recent clear-cut) was also high relative to the pine and pre-harvest switchgrass ecosystems. This illustrates the importance of maintaining vegetation cover to reduce local surface temperature. Second, I found that the 30-year mean change in global energy balance (i.e., radiative forcing) from planting a pine ecosystem rather than a switchgrass field was positive (pine warms climate) when considering changes in albedo and carbon measured using eddy-covariance systems. When including harvested carbon, pine and switchgrass can have similar global radiative forcing if all harvested pine carbon is stored, but harvested switchgrass carbon is burned. However, no scenarios I explored resulted in a strong negative radiative forcing by the pine ecosystem relative to the switchgrass field. These results show that afforestation or reforestation in the eastern United States may not result in any climate benefit over planting a switchgrass field. However, the presence of vegetation in both ecosystem types offers a clear benefit by cooling local surface temperatures. / Doctor of Philosophy / Humans are changing the Earth's climate by using oil and gas as fuel that emits greenhouse gases, mainly carbon dioxide, into the atmosphere. Planting trees to reestablish forests is a natural solution for climate change because forests absorb carbon dioxide from the air, but reforestation also changes the Earth's climate in other ways. For example, forests are generally darker than crops and grasses and absorb more sunlight, which traps energy in the atmosphere that can warm global temperature. These non-carbon effects can potentially offset the climate benefit from absorbed carbon dioxide. An alternative natural climate solution is to replace oil and gas with fuels derived from plants, known as bioenergy. Here I compared the local and global climate influence of a tree plantation (loblolly pine) to a bioenergy crop (switchgrass). I found that the local temperature of pine and switchgrass were similar in the summer when the grass was growing, and both were cooler than bare-ground, which was unable to evaporate and transpire water to the atmosphere. Over 30 years, I found that pine and switchgrass absorb similar amounts of carbon. The pine forest absorbs more carbon than switchgrass when it is fully grown but releases carbon during the first five years of growth. As a switchgrass field is brighter than a pine forest, planting a pine forest instead of a switchgrass field warms the Earth's climate. However, assuming no carbon from the harvested trees is released to the atmosphere, the pine and switchgrass have the same influence on global climate. My findings show that a pine plantation and a bioenergy crop can have similar climate benefits when carbon is stored in forests.

Orientador: Marcos Pereira Marinho Aidar / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-21T19:18:09Z (GMT). No. of bitstreams: 1 Marchiori_NidiaMara_M.pdf: 3439360 bytes, checksum: 8e5d49e665742675abd331ec9cff9ba4 (MD5) Previous issue date: 2012 / Resumo: O Nitrogênio é um nutriente essencial para o crescimento das plantas e produtividade de um ecossistema, visto sua ação como limitante para a fotossíntese ou relação com a reflectância da luz (albedo). Além disso, detém importância ecológica por ser uma ferramenta para a categorização de espécies em classes sucessionais baseado na utilização de suas formas disponíveis. Dessa forma, a compreensão da fisiologia do uso de N é essencial, especialmente em florestas tropicais, onde existem poucos estudos com essa abordagem. A Mata Atlântica (MA) é originalmente a segunda maior floresta tropical do continente americano, contudo grande parte de sua área e biodiversidade foi perdida e atualmente essa Floresta é definida como um "hotspot" para conservação da biodiversidade. O conhecimento e entendimento da estrutura e do funcionamento de ecossistemas complexos como os que compõem a MA é de suma importância para a discussão de temas atuais como o balanço de carbono global, nutrição vegetal e mudanças climáticas. Dentre os principais objetivos foram: a caracterização fitossociológica e estrutural de um trecho de Floresta Ombrófila Densa Montana (FODM), elucidar as estratégias de utilização de nitrogênio pelas plantas e avaliar através de parâmetros foliares, as respostas das plantas frente à mudança da estação do ano e a sazonalidade intrínseca. A área de coleta estava localizada na microbacia Ribeirão Casa de Pedra, Núcleo Santa Virgínia/Parque Estadual da Serra do Mar- São Luiz do Paraitinga, SP. Quanto à estrutura e composição do trecho de FODM estudado pode-se verificar uma floresta em estádio secundário inicial de regeneração avançando para uma condição mais tardia, sendo essa definição baseada tanto no histórico de utilização da área, quanto na composição de espécies e fisiologia do uso de nitrogênio. Assim, os resultados indicaram que em FODM há intensa diversidade biológica e diversidade funcional. Importante ressaltar também que esse projeto de mestrado foi parte integrante do Projeto Temático "Carbon tracker and water availability: controls of land use and climate changes" (Clima - FAPESP 08/58120-3; período de 2009-2013; coordenação Humberto Ribeiro da Rocha), cujo objetivo principal foi a quantificação à longo prazo da dinâmica dos fluxos de água, energia e CO2 em Biomas de Cerrado e Mata Atlântica no sudeste do Brasil / Abstract: Nitrogen is an essencial nutrient for plant growth and ecosystem productivity, either by limiting photosynthesis or related to the light reflectance (albedo). In addition, N has an ecological importance because it can be a tool for the categorization of species in ecological succession and functional types based on the use of its available forms. Thus, understanding the physiology of N use is essential, especially in tropical forests, where despite the impending increase of this element as a result of intensive fertilization or atmospheric deposition there are few studies using this approach. The Atlantic Forest (AF) is originally the second largest rainforest at the America continent, but much of its area and biodiversity has been lost and now the forest is defined as a "hotspot" for biodiversity conservation. The knowledge and understanding of the structure and functioning of complex ecosystems such as those that comprise the AF is of paramount importance for the discussion of current issues as the global carbon balance, plant nutrition and climate change. The main aims were: phytosociological and structural characterization of the tree component in a Montane Tropical Rainforest, understand the strategies of nitrogen use by plants and assess through leaf parameters, the response of plants to the change of season and intrinsic seasonality. The study area of the three chapters that follow are inserted in the watershed Ribeirão Casa de Pedra, Núcleo Santa Virginia Parque Estadual da Serra do Mar, located in São Luiz do Paraitinga-SP. The results indicated that Montane Tropical Rainforest was in initial secondary stage of regeneration evolving to a climax condition, based on the past human disturbance in the area, species composition and physiology of N use. Also indicated that this forest has many species and functional diversity. It is also important to note that this Master's project is part of the Thematic Project "Carbon tracker and water availability: controls of land use and climate changes" (Climate - FAPESP 08/58120-3; period 2009-2013; coordinated by Humberto Ribeiro da Rocha), whose main objective is to quantify the long-term dynamics of fluxes of water, CO2, energy at Cerrado and Atlantic Forest biomes in southeastern Brazil / Mestrado / Biologia Vegetal / Mestra em Biologia Vegetal

Land ice is losing mass to the worlds oceans at an accelerated rate. The worlds glaciers contain much less ice than the ice sheets but contribute equally to eustatic sea level rise and are expected to continue to do so over the coming centuries if global temperatures continue to rise. It is therefore important to characterize the mass balance of these glaciers and its relationship to climate trends and variability. In the Canadian High Arctic, analysis of long-term surface mass balance records shows a shift to more negative mass balances after 1987 and is coincident with a change in the mean location of the July circumpolar vortex, a mid-troposphere cyclonic feature known to have a strong influence on Arctic summer climate. Since 1987 the occurrence of July vortices centered in the Eastern Hemisphere have increased significantly. This change is associated with an increased frequency of tropospheric ridging over the Canadian High Arctic, higher surface air temperatures, and more negative glacier mass balance. However, regional scale mass balance modeling is needed to determine whether or not the long-term mass balance measurements in this region accurately reflect the mass balance of the entire Canadian High Arctic. The Canadian High Arctic is characterized by high relief and complex terrain that result in steep horizontal gradients in surface mass balance, which can only be resolved if models are run at high spatial resolutions. For such runs, models often require input fields such as air temperature that are derived by downscaling of output from climate models or reanalyses. Downscaling is often performed using a specified relationship between temperature and elevation (a lapse rate). Although a constant lapse rate is often assumed, this is not well justified by observations. To improve upon this assumption, near-surface temperature lapse rates during the summer ablation season were derived from surface measurements on 4 Arctic glaciers. Near-surface lapse rates vary systematically with free-air temperatures and are less steep than the free-air lapse rates that have often been used in mass balance modeling. Available observations were used to derive a new variable temperature downscaling method based on temperature dependent daily lapse rates. This method was implemented in a temperature index mass balance model, and results were compared with those derived from a constant linear lapse rate. Compared with other approaches, model estimates of surface mass balance fit observations much better when variable, temperature dependent lapse rates are used. To better account for glacier-climate feedbacks within mass balance models, more physically explicit representations of snow and ice processes must be used. Since absorption of shortwave radiation is often the single largest source of energy for melt, one of the most important parameters to model correctly is surface albedo. To move beyond the limitations of empirical snow and ice albedo parameterizations often used in surface mass balance models, a computationally simple, theoretically-based parameterization for snow and ice albedo was developed. Unlike previous parameterizations, it provides a single set of equations for the estimation of both snow and ice albedo. The parameterization also produces accurate results for a much wider range of snow, ice, and atmospheric conditions.

No description available.