This dissertation consists of three parts, each devoted to a particular issue of significant importance for satellite-based remote sensing of cirrus clouds. In the first part, we develop and present a fast infrared radiative transfer model on the basis of the adding-doubling principle. The model aims to facilitate the radiative transfer computations involved in hyperspectral remote sensing applications. The model is applicable to a variety of cloud conditions, including vertically inhomogeneous or multilayered clouds. It is shown that for hyperspectral applications the model is two order-of-magnitude faster than the well-known discrete ordinate transfer (DISORT) model, while maintains a similar accuracy. The second part is devoted to the investigation of uncertainties in the FSSP (Forward Scattering Spectrometer Probe) measurement of cloud extinction by small ice particles. First, the single-scattering properties of small ice particles in cirrus clouds are derived and compared to those of equivalent spheres according to various definitions. It is found that, although small ice particles in cirrus clouds are often “quasi-spherical”, their scattering phase functions and asymmetry factors are significant different from those of ice spheres. Such differences may lead to substantial underestimation of cloud extinction in FSSP measurement, if small ice particles are assumed to be spheres. In the third part, we present a comparison of cirrus cloud optical thickness retrievals from two important instruments, MODIS (Moderate Resolution Imaging Spectrometer) and POLDER (Polarization and Directionality of Earth’s Reflection), on board NASA’s A-train satellite constellation. The comparison reveals a large difference. Several possible reasons are discussed. It is found that much of the difference is attributable to the difference between the MODIS and POLDER retrieval algorithm in the assumption of cirrus cloud bulk scattering properties. Potential implications of the difference for climate studies are investigated. An important finding is that the use of an unrealistic cirrus bulk scattering model might introduce artificial seasonal variation of cirrus optical thickness and shortwave radiative forcing into the retrieval.

The Antarctic ice sheet mass budget is a very important factor for global sea level. An understanding of the glacial dynamics of the Antarctic ice sheet are essential for mass budget estimation. Utilizing a surface velocity field derived from Radarsat three-pass SAR interferometry, this study has investigated the strain rate, grounding line, balance velocity, and the mass balance of the entire Lambert Glacier – Amery Ice Shelf system, East Antarctica. The surface velocity increases abruptly from 350 m/year to 800 m/year at the main grounding line. It decreases as the main ice stream is floating, and increases to 1200 to 1500 m/year in the ice shelf front. The strain rate distribution defines the shear margins of ice flows. The major ice streams and their confluence area experience the most severe ice deformation. The width of the shear margin decreases as it flows downstream except for the convergent areas with tributary glaciers. The grounding line for the main ice stream and the boundary of Amery Ice Shelf and surrounding tributary glaciers is delineated. The total basal melting is estimated to be 87.82 ± 3.78 Gt/year for the entire Amery Ice Shelf. Compared with the ice flux (16.35 ± 3.11 Gt/year) at the ice shelf front, basal melting is apparently the dominant discharging process of the system. The melting rate for the Amery Ice Shelf decreases rapidly from the grounding zone (21.64 ± 2.17 m/year) to the ice shelf front (-0.95 ± 0.14 m/year). The Lambert Glacial Basin contributes the total ice mass of 95.64 ± 2.89 Gt/year to the ocean, which is equivalent to increasing the global sea level by 0.24 mm/year. Considering 90.54 ± 1.55 Gt/year of snow accumulation, the entire Lambert Glacier – Amery Ice Shelf system is slightly negatively imbalanced at -5.09 ± 3.46 Gt/year. Although the entire system is estimated to have a slight negative mass balance, three sub-glacial systems have a net positive mass balance due to a relatively high snow accumulation rate or relatively slow ice motion. Considering the large mass loss in West Antarctica, it is believed that the overall mass budget in Antarctica is negative based on this research.

During the last century wetlands have considerably decreased. The principal cause is urbanization, especially in large urban regions such as the Houston area. In order to protect the remaining wetlands, they have to be monitored carefully. However monitoring wetland is a difficult and time-demanding task because it has to be done repetitively on large areas to be effective. This study was conducted to determine if Geographical Information System (GIS) and remote sensing technologies would allow accurate monitoring of wetland as a less time-consuming method. With this idea, a suitability model was developed to delineate wetlands in the Houston area. This model combined GIS and remote sensing technologies. The data used for this study were as high spatial resolution as possible and were generally easy to obtain. This suitability model consisted of four submodels: hydrology, soil, vegetation and multi- attribute. Each submodel generated a Wetland Suitability Index (WSI). Those WSI were summed to obtain a general WSI. The suitability model was calibrated using half of the study area. During calibration, the general model was evaluated as well as each individual index. Generally, the model showed a lack of sensitivity to changes. However, the model was slightly modified to improve the delineation of upland wet- lands by increasing the weight of the soil submodel. This model was validated using the second half of the study area. The validation results improved a bit compared to the calibration results; however they remained weak. It was demonstrated that the model does not favor riverine wetlands over upland wetlands, nor large size wetlands. The model ground truth data were evaluated and were suffciently proven to be up to date. Those results indicated that the weakness of the model must come from inac- curacy in the input data. Therefore, the study showed that while existing computing capacity supports remote delineation, spatial accuracy is still insuffcient to perform correct wetland delineation using remote sensing and GIS technologies.

An improved physically-based rainfall algorithm was developed using AMSR-E data based on a radiative transfer model. In addition, error models were designed and embedded in the algorithm to assess retrieval errors quantitatively and to reduce net retrieval uncertainties. The algorithm uses six channels (dual polarizations at 36.5, 18.7 and 10.65GHz) and retrieves rain rates on a pixel-by-pixel basis. Monthly rain totals are estimated by summing average rain rates computed by merging six rain rates based on proper weights that are estimated from error models. Error models were constructed based upon the principal error sources of rainfall retrieval such as beam filling error, drop size distribution uncertainty and instrument calibration errors. Several improved schemes that minimize uncertainties of the rainfall retrieval were developed in this study. In particular, improved offset correction that corrects the biases near zero rain plays a very important role for reducing uncertainties which are mainly driven by calibration uncertainty including the modeling errors. AMSR-E's larger calibration uncertainty was substantially absorbed by this offset correction as well as by the weighted average scheme to combine all six channels optimally. As a framework for inter-comparison with the experimental algorithm, the current operational algorithm (NASA, level 3 algorithm) was also updated with respect to AMSR-E data. The experimental algorithm was compared with the operational algorithm for both AMSR-E and TMI data and rainfall retrieval uncertainties were analyzed using error models. When the experimental algorithm was used, many limitations of the operational algorithm were overcome and uncertainties of rainfall retrieval were considerably eliminated.

Thesis (M. Sc.)--York University, 2000. Graduate Programme in Earth and Space Science. / Typescript. Includes bibliographical references (leaves 107-111). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pMQ56168.

Thesis (M.S.)--Brigham Young University. Dept. of Electrical and Computer Engineering, 1999. / Includes bibliographical references (p. 177-180).

<p> Climate warming is occurring at an unprecedented rate in the Arctic, seriously impacting sensitive environments, and triggering land cover change. These changes are compounded by localized human influences. This work classifies land cover change for the Lower Yenisei River, identifies those changes that were climate- and anthropogenic- induced, and discusses the implications for the underlying permafrost system. This is accomplished using a modified version of the &ldquo;Landsat dense time stacking&rdquo; methodology for three time periods spanning 29 years that are representative of Russian socio-economic transitions during the mid- to late-1980s (1985-1987), the early 2000s (2000-2002), and the contemporary 2010s (2012-2014). The classified area includes three cities indicative of different post-Soviet socio-economic situations, including continued population and infrastructure decline (Igarka), a relatively stable community (Dudinka), and a community receiving local reinvestment (Norilsk). The land cover classification, in tandem with regional climate reanalysis data, enabled climate- and anthropogenic- induced changes to be identified, characterized, and quantified. Climatic changes within the natural environments have produced a steady greening effect throughout the study area, as well as an increase in large lake abundance, indicative of permafrost degradation. Pollution, in close proximity to heavy industrial activity, caused a secondary plant succession process. The results of this work provide both map products that can be applied to future research in this region, as well as insights into the impacts of the warming climate and human presence on sensitive Arctic environments.</p>

Estimating recharge is a critical aspect of groundwater management, when aquifer resources are constrained by multiple users. The Edwards Aquifer, an artesian aquifer underlying Austin and San Antonio, Texas, sustains municipalities, farmers and fragile habitats at discharge locations. Rising municipal demand for Edwards water supports the need for effective conservation over time to maintain the well-being of all users. Predicting recharge is a valuable tool for determining future available resources. Evapotranspiration (ET) accounts for a majority of water loss following precipitation, significantly affecting recharge. Developing a method for accurate regional estimates of ET is complicated by aquifer characteristics, expensive instrumentation, and a variable climate. This study investigates a specific method for estimating regional potential ET (ETp), by combining the Priestley-Taylor equation with data primarily retrieved from the Moderate-Resolution Imaging Spectroradiometer. Improved resolution and timing of satellite measurements provides greater regional specificity for variables related to ET calculations. ETp is then estimated for 2004 and 2005, utilizing data from MODIS, aboard NASA’s Aqua and Terra satellites. Land surface temperature, leaf area index and albedo retrieved from MODIS replace in situ measurements, which are often nonexistent in a regional context. Incoming radiation, a direct input in the Priestley-Taylor equation, is retrieved from the National Center for Environmental Prediction’s North American Regional Reanalysis Model (NARR). Results show methods overestimate ET between 400% to over 1000% when compared to actual ET (ETa) at two locations in the northeast portion of the aquifer. Correlation is improved when ETp is treated as an instantaneous rate rather than daily. During months of above average precipitation, which are more representative of potential conditions, instantaneous ETp exceeded ETa by an average of 81%, with a root mean squared error of 1.15 mm/30min and an average positive bias of 2.84 mm/30min. Considering the soil moisture limited conditions throughout Central Texas, a positive bias is not surprising. Incorporating a calibrated Priestly-Taylor could improve accuracy, but estimating regional ETp remains restricted by available daily data necessary for calculations and comparison. / text

Patterns of surface sediment concentration distribution in rivers are significant for understanding the broad ranges of fluvial environmental systems. In the case of the Amazon Basin, the complexity in the sediment pattern distribution is affected by the anabranching channel pattern of the Amazon River, the input by tributaries (some of which are among the largest rivers on earth) and the existence of huge and complex floodplains. Until recently, the assessment of sediment fluxes has been concentrated on hydro-sedimentological techniques in the Amazon Basin; however, efforts on characterizing the patterns of sediment transport have been neglected. This study aims to improve the understanding of the pattern of sediment distributions over a large scale in the Amazon River by estimating surface sediment concentration with remote sensing techniques. Field acquired surface sediment concentration values were supplied from three gauging stations representing the upstream, midstream and downstream sections of the Amazon River from 2000 to 2010 and calibrated with MODIS surface reflectance products (N=207, 232, 313, respectively). Empirical models were derived with robust causalities (0.63<R2<0.92) between field surface sediment concentration and surface reflectance from each station; however, sensitivity of reflectance around each stations were shown to be significantly affected by the local hydrological behaviors, leaving implications on analysis of the geomorphic characteristics affecting these associations. Overall, the capability of the remote sensing-based platform introduced in this study is successfully demonstrated by capturing the spatial and temporal variability of surface sediments in the Amazon River Basin, which is the largest and the most complex river system on earth. / text

Urban growth is one type of urban development. Many Canadian cities have dramatically evolved over the past twenty years. Along with the rapid growth of urban region, urban sprawl has become one of the most significant issues challenging most cities. Remote sensing techniques are frequently used to analyse urban growth and sprawl. In this study, three temporal satellite images, which were taken at 1990, 2000, 2010 respectively, are classified using software ENVI to determine the urban extent and growth pattern of the city of London, Ontario, Canada. Statistical models including Shannon‘s entropy and Pearson‘s chi-square are applied to calculate the degree of sprawl and degree of freedom of London. Moreover, the overall degree of goodness of the urban growth is calculated as a promotion of the former two statistic models towards the analysis of urban growth. The results shows London is sprawled in the past 20 years (from 1990 to 2010) with a decreasing degree of freedom and a moderate degree of goodness of urban growth. Apart from mathematical analysis, policies that have been implemented since 1990s to curb urban sprawl in London are reviewed. Key factors that impact the urban growth pattern of London are identified through reviewing. It is found that 1993‘s annexation, the creation of Urban Growth Boundary and changed political intentions are the main factors. By analyze these factors, it also help to explain the results derived from mathematical models. Brownfield redevelopment, residential intensification, smart moves are regarded as the most important strategies to deal with urban sprawl carried out by London‘s local government. It also witnesses a great impact of policies initiated by the province on a mid-sized municipality such as London. It is argued that municipalities gain only limited political autonomy and administrative capacity. Recommendations are addressed specifically for the related strategies for further promotions. / published_or_final_version / Urban Planning and Design / Master / Master of Science in Urban Planning