Abstract Spatial structure of habitats has been found to affect the species abundance and distribution patterns in heterogeneous environments. In this thesis, I studied landscape responses of the Siberian flying squirrel in a boreal forest context in northern Finland. Studies were conducted at several spatial scales in order to identify landscape characteristics that are associated with the species occurrence at a local scale and its distribution patterns at a regional scale. Data on species presence and absence in forest areas were collected in the field. Habitat patterns in landscapes were analysed from satellite images and landscape metrics concerning landscape structure were quantified in Geographic Information Systems (GIS). Results of this study are in agreement with the general landscape ecological theory and findings in the field. In northern Finland, the distribution of the Siberian flying squirrel primarily follows the spatial extent of spruce-dominated forests but that its actual occurrence is dependent on the scale of observation and the habitat structure. At a home range scale the abundance of deciduous trees in old spruce forest increases the probability that a forest site is occupied by the species, whereas at a local scale the amount of such spruce forests and linkages between habitat patches play an important role. At a regional scale, an increase in open areas and the dominance of pine makes the habitat unsuitable and restricts the presence of the species. Findings of the present research forward practical forest management planning at a large scale and may help set general conservation goals for the Siberian flying squirrel. When managing the species in a complex network of habitat patches in heterogeneous landscapes, spatial dispersion of potential habitat patches as well as connecting habitat and their temporal development should be considered carefully. For this purpose, remote sensed images and GIS are valuable and useful tools. Satellite-image based landscape analysis is presently developing rapidly and hopefully this methodology will soon become a common practice in landscape ecological research and everyday forest management planning.

The purpose of this study is to validate the ability of the Simplified Surface Energy Balance (SSEB) approach and the Simple Method to provide AET estimates for wetland recovery efforts. The study utilizes the MODIS sensor aboard NASA's Terra satellite and SFWMD solar radiation data to derive AET values for South Florida. The SSEB/Simple-Method approach provided mixed results with good agreement with control values during dry season (rave (59) = 0.700, pave < 0.0005) and poor agreement during wet season (rave(46) = 0.137, pave = 0.304). Further refinement is needed to make this method viable for yearly estimates due to the poor performance during wet season months. This approach can prove useful for short term wetland recovery assessment projects that occur during the dry season and/or long term projects that compare AET rates from a site from dry season to dry season.

Abstract not available.

Crop residues left on agricultural field after harvest is an effective alternative, among others, to minimize the harmful effects of wind and water erosion, to increase the quantity of nutriments in the soils and to reduce CO2 emissions in the atmosphere. During this master's degree, two methods used in remote sensing were applied to the Probe-1 hyperspectral image of an agricultural field situated in the Southeast Saskatchewan, crop residue index and neural networks. The purpose was to determine which of the two methods was the most effective to accurately map and estimate crop residues. It is worth while mentioning that this the first time hyperspectral data were used to mapping ends of crop residue, which constitutes an advancement in the domain. To complete the dataset, several spectral reflectance measures were taken from different types of crop residues (corn, wheat, herb, soya and sunflower) and different types of bare soils, obtained by the spectroradiometer GER3700. Nine crop residue indices were used (BI, CAI, NDI-1, NDI-2, SACRI-1, SACRI-2, MSACRI-1, MSACRI-2 and CRIM). (Abstract shortened by UMI.)

Since the 1960s, warming air and sea surface temperatures have led to decreasing sea ice extent and longer periods of open water in the Canadian Arctic Archipelago (CAA). Recent and rapid changes have also been observed in the ice discharge patterns of glaciers in this region. For example, Trinity and Wykeham glaciers on the Prince of Wales Icefield (POW), SE Ellesmere Island, contributed ~62% of total ice discharge to the ocean from the Canadian Arctic Archipelago in 2016, compared to ~22% in 2000. Given these changes, an important question is whether there is a relationship between changing sea ice conditions (e.g., extent, freeze up dates, break up dates) and iceberg production from these glaciers. This study used synthetic aperture radar (Radarsat-1, 2 and ALOS PALSAR) and optical (Landsat-7 and 8) imagery to identify iceberg plume events and sea ice break-up/freeze-up dates between 1997 and 2015 for 40 tidewater glaciers around the POW. Results show a clear relationship between the presence of sea ice and the production of icebergs from glaciers, with most events occurring during the open water season and fewer when sea ice was present. While there have not been clear increasing trends of icebergs produced from all glaciers in the POW, Trinity and Wykeham glaciers show that increases in detected iceberg plumes coincide with increases in previously measured glacier velocity and significant terminus retreat. Comparison to ocean temperature, surface air temperature from NCEP/NCAR reanalysis and tidal data showed no clear relationship with increased calving events, however further research into all factors is recommended. It is likely that there are several factors contributing to the spatial and temporal variability of iceberg production from the POW.

The Microwave Remote Sensing Lab (MIRSL) at the University of Massachusetts has developed a second-generation L-band synthetic aperture microwave radiometer referred to as the Electronically Steered Thinned Array Radiometer, or ESTAR, which measures soil moisture or ocean salinity from an airborne platform. This dissertation reviews the basics of synthetic aperture microwave radiometry, then details recent modifications to the ESTAR instrument, including the change to a horizontally polarized antenna, and improvements to the instrument's thermal control. The dissertation discusses calibration methods, including corrections to the null feedback radiometer (NFR) data used to form the system response matrix, or G-matrix. It also describes image calibration, noting steps taken to reduce image ripple. Results obtained during the Southern Great Plains 1997 (SGP'97) hydrology experiment in Oklahoma are discussed and compared to rainfall data obtained from the Oklahoma Mesonet system of weather stations. This data set is the largest one of its type obtained by ESTAR to date, in terms of area of geographical and temporal coverage.

This dissertation presents the Imaging Wind and Rain Airborne Profiler (IWRAP), the first high-resolution dual-band airborne Doppler radar designed to study the inner core of Tropical Cyclones (TCs). IWRAP is usually operated from a National Oceanic and Atmospheric Administration (NOAA) WP-3D aircraft during missions through TCs and severe ocean storms. The system is designed to provide high-resolution dual-polarized C- and Ku-band reflectivity and Doppler velocity profiles of the atmospheric boundary layer (ABL) within the inner core precipitation bands of TCs and to study the effects precipitation has on ocean wind scatterometry as it applies to TCs. A summary of the principles of operation and the design of the instrument is given, with an emphasis on the unique digital receiver. Airborne ocean backscatter measurements at C- and Ku-band wavelengths and HH and VV polarizations obtained in moderate to very high wind speed conditions (25–65 m·s−1) are presented. The differences between these measurements and current geophysical model functions (GMFs) are reported. The impact of these results on satellite-based scatterometry is discussed, and their application is illustrated through the reprocessing of QuikSCAT passes with the new GMFs. The use of dual wavelength techniques to determine differential attenuation from IWRAP's dual band reflectivity measurements, as well as to derive rainfall rates and drop-size distribution parameters is also addressed. In addition, results on the use of the radar Doppler velocity measurements to derive the three-dimensional (north, east and vertical) components of the ABL winds within rainbands of TCs are presented. Validation of these results is performed by comparison against other available datasets. IWRAP's unique imaging capability provides, to our knowledge, the highest-resolution measurements of the ABL winds of a hurricane ever obtained.

The relationship between microwave imaging radar measurements of the nearshore ocean region and nearshore dynamics is studied. Normalized radar cross section and Doppler velocity are estimated from radar measurements of nearshore waves at near-grazing angles. Radar scattering is classified using joint histograms of radar cross section and Doppler velocities. Scattering in these distributions is investigated through comparisons with theoretical wave predictions, video particle image velocimetry (PIV), and in situ acoustic Doppler velocimeter (ADV) measurements. This analysis shows that shoaling and breaking waves measured through radar grating lobes significantly affect Doppler velocities near the edges of the images and also scattering from the back faces of waves. Doppler velocities from breaking waves are found to agree well with wave phase velocity predictions in the surf zone (the rms difference is 0.14 m/s), and large radar cross section features are correlated with breaking waves and the motion of surf-zone bores in video imagery. Differences in inter-bore velocities are expected, since the measurements are not collocated. However; Doppler inter-bore velocities are found to correlate well with fluid velocities (the correlation coefficient is 0.65), but are offset by around 0.8 m/s. This offset may be due to a combination of the Bragg wave phase velocities, radar sensitivity to short wavelength waves in the nearshore which is limited by the spatial resolution of the radar, and inherent biasing of Doppler velocities towards velocities of large NRCS scattering. In low-wind conditions, radar measurements of the nearshore show patches of increased backscatter. Animation of sequences of the images shows movement of these patches. A feature-tracking algorithm based on PIV is presented to quantify the velocities of the observed features. The nature of the patches is also investigated through comparison with video images. It is concluded that the patches of backscatter are due to low-grazing angle scattering from streaks of foam, however contributions from mechanically-generated surface roughness are not ruled out. Comparisons between surface velocities derived from the feature-tracking algorithm and subsurface velocities measured by in situ current meters show best agreement for sensors beyond the surf zone. It is concluded that the estimated velocity fields are related to nearshore flows such as wave-induced cell circulations and longshore currents.

Over the past few decades, several single radar methods have been developed to probe the kinematic structure of storms. All these methods trade angular-resolution to retrieve the wind-field. To date, the spaced-antenna method has been employed for profiling the ionosphere and the precipitation free lower atmosphere. This work focuses on applying the spaced-antenna method on an X-band active phased-array radar for high resolution horizontal wind-field retrieval from precipitation echoes. The ability to segment the array face into multiple displaced apertures allows for flexible spaced-antenna implementations. The methodology employed herein comprises of Monte-Carlo simulations to optimize the spaced-antenna system design and analysis of real data collected with the designed phased-array system. The contribution that underpins this dissertation is the demonstration of qualitative agreement between spaced-antenna and Doppler beam swinging retrievals based on real data. First, simulations of backscattered electric fields at the antenna array elements are validated using theoretical expressions. Based on the simulations, the degrees of freedom in the spaced-antenna system design are optimized for retrieval of mean baseline wind. We show that the designed X-band spaced-antenna system has lower retrieval uncertainty than the existing S-band spaced-antenna implementation on the NWRT. This is because of the flexibility to synthesize small overlapping apertures and the ability to obtain statistically independent samples at a faster rate at X-band. We then demonstrate a technique to make relative phase-center displacement measurements based on simulations and real data from the phased-array spaced-antenna system. This simple method uses statistics of precipitation echoes and apriori beamwidth measurements to make field repeatable phase-center displacement measurements. Finally, we test the hypothesis that wind-field curvature effects are common to both the spaced-antenna and Doppler beam swinging methods. Based on a close-range winter storm data set, we find that the spaced-antenna and fine-resolution Doppler beam swinging retrievals are in qualitative agreement. The correlation between the spaced-antenna and fine-resolution Doppler beam swinging retrievals was 0.57. The lowered correlation coefficient was, in part, due to the high standard deviation of the DBS retrievals. At high wind-speeds, the spaced-antenna retrievals significantly departed from variational retrievals of mean baseline wind.

This dissertation presents the design and operation of a high-resolution frequency-modulated continuous-wave (FM-CW) radar system to study the structure and dynamics of clear-air turbulence in the atmospheric boundary layer (ABL). This sensitive radar can image the vertical structure of the ABL with both high spatial and temporal resolutions, and provide both qualitative information about the morphology of clear-air structures and quantitative information on the intensity of fluctuations in refractive-index of air. The principles of operation and the hardware and data acquisition characteristics of the radar are described in the dissertation. In October 1999, the radar participated in the Cooperative Atmosphere-Surface Exchange Study (CASES'99) Experiment to characterize the temporal structure and evolution of the boundary-layer features in both convective and stable conditions. The observed structures include clear-air convection, boundary layer evolution, gravity waves, Kelvin-Helmholtz instabilities, stably stratified layers, and clear-air turbulence. Many of the S-band radar images also show high-reflectivity returns from Rayleigh scatterers such as insects. An adaptive median filtering technique based on local statistics has, therefore, been developed to discriminate between Bragg and Rayleigh scattering in clear-air radar observations. The filter is tested on radar observations of clear air convection with comparison to two commonly used image processing techniques. The dissertation also examines the statistical mean of the radar-measured [special characters omitted] for clear-air convection, and compares it with the theoretical predictions. The study also shows that the inversion height, local thickness of the inversion layer, and the height of the elevated atmospheric layers can be estimated from the radar reflectivity measurements. In addition, comparisons to the radiosonde-based height estimates are made. To examine the temporal and spatial structure of [special characters omitted], the dissertation presents two case studies with the measurements of remote (the FM-CW radar and Doppler lidar) and in-situ (research aircraft, kite, and radiosonde) sensors from the stable nighttime boundary layer. It also presents a unique observation of evolution of the convective and nocturnal boundary layers by the S-band radar, and provides description of the observed boundary layer characteristics with the aid of in-situ measurements by the 55m instrumented tower and radiosonde.