Showing papers on "Spectroradiometer published in 1977"
TL;DR: A joint project to monitor the spectral distribution of daylight was instituted between the Smithsonian Radiation Biology Laboratory and the National Physical Laboratory of Israel as discussed by the authors, where the purpose of this project is to gather sufficient data to study the variations in spectral quality due to natural seasonal and atmospheric variations at various geographical locations.
4 citations
01 Sep 1977
TL;DR: In this article, the authors compare and quantify the airborne spectroradiometer multispectral data to ground truth water quality measurements obtained in Lake Powell, Utah, during June 1975.
Abstract: : During the past three years there has been a renewed interest in the methodology and procedures used to monitor water quality in fresh and salt water regimes. However, there still exists a need to calculate quantitatively the amount of surface turbidity by remote sensing methods to provide rapid and synoptic water quality surveys. Recently a 500-channel airborne spectroradiometer, which may provide a quantitative means of comparing high resolution multispectral data to water quality parameters, has been designed at the the NASA Goddard Institute for Space Studies (GISS). The objective of this study is to correlate and quantify the airborne spectroradiometer multispectral data to ground truth water quality measurements obtained in Lake Powell, Utah, during June 1975. A ground truth water sampling program was accomplished during 9-16 June 1975 for correlation to an aircraft spectroradiometer flight. Field measurements were taken of percentage of transmittance, surface temperature, pH and secchi disk depth. Also, percentage of transmittance was measured in the laboratory for the water samples. In addition, electron micrographs and suspended sediment concentration data were obtained of selected water samples located at Hite Bridge (Mile 171), Mile 168, Mile 150 and Bullfrog Bay (Mile 122). Airborne spectroradiometer spectra were selected which correlated to the Hite Bridge (Mile 171), Mile 168, Mile 150 and Bullfrog Bay (Mile 122) test sites.
3 citations
01 Sep 1977
TL;DR: In this paper, the NPS Spectroirradiometer (spectral irradiance meter) incorporates a rotating spectral wedge filter and was developed to measure the spatial distribution of downwelling underwater solar irradiance.
Abstract: : The NPS Spectroirradiometer (spectral irradiance meter) incorporates a rotating spectral wedge filter and was developed to measure the spatial distribution of downwelling underwater solar irradiance. Spectral irradiance data in the 402 to 577 nm regime was observed to depths of 130 m under both clear and foggy sky conditions. Diffuse attenuation coefficients, k, for downwelling light at selected wavelength/depth combinations were calculated from the observed spectral irradiances. The downwelling spectral irradiance values obtained ranged from 436 microwatts/sq. cm/nm at 494 nm to .00150 microwatts/sq cm/nm at 577 nm and are numerically comparable to data from other studies of coastal waters. The calculated values for five selected wavelengths, namely 418, 453, 487, 522, and 557 nm, ranged from .097/m at 418 nm to .274/m at 557 nm and are representative values. The results of the measurements indicate that the NPS Spectroirradiometer provides a practical method of determining irradiance distributions.
1 citations
TL;DR: The function of a field-averaging spectrograph camera is the same as a spectroradiometer, which is widely used for remote sensing applications at the present time and is more compact, portable, and lower priced than conventional instruments.
Abstract: A field-averaging spectrograph camera utilizing a continuous interference filter and a step tablet has been investigated and its characteristics measured. Using color patches, the values obtained with the camera are compared with those obtained by a spectroradiometer and a self-spectrophotometer. The results obtained with the photographic method show slightly higher values than those of the other methods in the measured wavelength region. In the measurement of spectral reflectances of two-color patches with different ratios of area within a field of view angle, the same reversal point of the relative reflectance curves is observed with this camera as the spectroradiometer. Therefore, the function of a field-averaging spectrograph camera is the same as a spectroradiometer, which is widely used for remote sensing applications at the present time. Moreover, it is more compact, portable, and lower priced than conventional instruments. The spectral reflectances of scenes were measured by photographic and spectroradiometer methods in field experiments. The spectral image of soil photographed by a beam split camera used with the field-averaging spectrograph camera is displayed in false color.
1 citations
01 Dec 1977
TL;DR: In this paper, a procedure for calibrating an infrared scanning spectroradiometer by a computerized parametric error analysis technique was developed, which is applicable to the radiometric calibration of any infrared radiometer.
Abstract: A procedure for calibrating an infrared scanning spectroradiometer by a computerized parametric error analysis technique was developed. The uncertainties in the radiometric measurements of scene radiance and (for the case of a blackbody scene) temperature due to possible uncertainties in the calibration target temperature, calibration target emissivity, and instrument temperature were calculated for a range of uncertainty levels in the parameters, as well as for a gamut of scent temperatures corresponding to a given spectral channel. This technique is applicable to the radiometric calibration of any infrared radiometer. It was applied specifically to the Cloud-Top Scanning (C.T.S) Radiometer, a three-channel instrument designed for aircraftborne cloud radiance measurements in the 6.75 and 11.5 micron thermal emission spectral regions.