Lau Yun Ngau, Patrick. / Bibliography: leaves 126-131 / Thesis (M.Ph.)--Chinese University of Hong Kong, 1985

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During snowmelt net radiation above a snow surface was measured simultaneously at forty-four locations to permit comparison of measurements in a black spruce forest with those in the open. / Data, obtained during cloudy daylight and at night were used to produce meaningful surface radiation maps of the experimental site. For all periods of observation the range in values recorded between any two sensors was greatest between those positioned in the forest. Spatially, net radiation varied most within the forest. The location of high and low net radiation values recorded during the day are the reverse at night. The spruce canopy reduces net radiation at the snow surface on cloudy days by obstructing a portion of the incident diffuse sky radiation. Conversely, the canopy is shown to exert considerable effect as a source of longwave radiation. Surface net longwave radiation increases sharply with proximity to trees. The effect of local and snow surface topography is greatest on clear days when irradiance is highly directional. On clear nights the forest edge is distinguished by a steep gradient of net radiation. On cloudy nights the variability and range in surface net radiation are greatly reduced.

Thesis (Ph. D.)--University of Hawaii at Manoa, 2004. / Includes bibliographical references (leaves 134-139). / Also available by subscription via World Wide Web / xvi, 139 leaves, bound ill. 29 cm

Thesis (Ph. D.)--University of Hawaii at Manoa, 2004. / Includes bibliographical references (leaves 134-139).

Soil moisture information can be used accurately in determining the timing and amount of irrigation applied to plants. Pan and Pan et al. proposed a robust and simple daily diagnostic equation for estimating daily soil moisture. The diagnostic equation evaluates the relationship between the soil moisture loss function and the summation weighted average of precipitation. The loss function uses the sinusoidal wave function which employs day of the year (DOY) to evaluate the seasonal variation in soil moisture loss for a given year. This was incorporated into the daily diagnostic equation to estimate the daily soil moisture for a location. Solar radiation is an energy source that drives the energy and water exchanges between vegetation and the atmosphere (i.e., evapotranspiration), and thus impacts the soil moisture dry-down. In this paper, two parameters (the actual solar radiation and the clear sky solar radiation) are introduced into loss function coefficient to improve the estimation of soil moisture. After the Introduction of the solar radiation data into soil moisture loss function, a slight improvement was observed in the estimated daily soil moisture. Pan observed that generally the correlation coefficient between the estimated and the observed soil moisture is above 0.75 and the root mean square error is below 5.0 (%v/v). The introduction solar radiation data (i.e. clear sky solar radiation and actual solar) improve the correlation coefficient average for all the sites evaluated by 0.03 when the root mean square error is generally below 4.5(%v/v) for the entire root zone.

A solar spectroradiometer is an instrument used for measuring the transmitted solar radiation on a quasi-continuous basis. An existing computer controlled solar spectroradiometer system has been modified and made operable. Test measurements have shown that the signal to noise ratio (which is time of day and wavelength dependent) is at an acceptable level. The chief use of the spectroradiometer will be for atmospheric transmittance studies, which will require calibration of the instrument. Strategies for calibrating the instrument have been discussed.

Three different types of radiometry have been examined to find the best type for solar spectral irradiance measurements requiring long-term (22 years) and ultra-high precision (0.1% uncertainty) in the near-UV, visible, and near infrared. It has been determined that the best radiometry uses the self-calibration technique developed at NBS using laser lines. Normalization techniques were applied to silicon reflectivity and quantum efficiency models for use with thermal sources and grating spectrometers. The results compared with similar laser-source calibration showed disagreement less than 0.1%. Germanium and GaAsP detectors were also investigated in the infrared and deep blue wavelengths. The germanium detector showed significant recombination loss of photogenerated carriers due to the ion implantation fabrication process. GaAsP detectors have very small dark currents ( < 1 nA), but also demonstrate significant recombination losses inside the photodiode. The possible loss mechanism of the Ge and GaAsP detectors are suggested for future study.

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Thesis (M. Sc.)--York University, 1997. Graduate Programme in Earth and Space Science. / Typescript. Includes bibliographical references (leaves 83-85). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pMQ27334.