Frank R. Schiebe

The Relationship of MSS and TM Digital Data with Suspended Sediments, Chlorophyll, and Temperature in Moon Lake, Mississippi

A comparison of six concurrent Landsat MSS and TM scenes was made to determine the relationship of Landsat digital data with suspended sediments, chlorophyll, and temperature in the surface water of an agricultural lake. There were no significant differences in best correlations between MSS or TM data with surface suspended sediments. Thus, the advantage of using MSS is the ability to monitor large areas with significantly less data. TM data can be efficiently used to monitor smaller lakes and reservoirs. TM Band 1 reflectance was the only Landsat data that accounted for at least 50% of the variability in the chlorophyll data. This would not be adequate for a monitoring program for chlorophyll in sediment dominated lakes, such as Moon Lake. TM thermal data were highly correlated with surface water temperature. TM measured surface water temperatures could be useful in determining water balance in small agricultural reservoirs. A monitoring program based on Landsat MSS and TM scanners can provide data on suspended sediments that would allow the location of reservoirs with significant suspended sediment and allow better conservation assessment and planning.

Remote Sensing of Lake Chicot, Arkansas: Monitoring Suspended Sediments, Turbidity, and Secchi Depth with Landsat MSS Data

This research used water quality data from Lake Chicot, Arkansas and a corresponding set of Landsat MSS data to compare the ability of satellite-based sensor systems to monitor suspended sediment concentration, Secchi disk depth, and nephelometric turbidity. Lake Chicot was selected, in part, because of the availability of a wide range of water quality conditions. Secchi disk depth and nephelometric turbidity are both optical measures of water quality and differ from suspended sediment concentration, which is a measure of the weight of inorganic particulates suspended in the water column. four different models for these relationships between the satellite data and the water quality data were tested: 1) simple linear regression analysis with the satellite data transformed to exo-atmospheric reflectance, 2) a simple linear regression involving a natural logarithm transformation of the satellite and water quality variables, 3) simple linear regression analysis of the digital chromaticity transformation of the satellite data and the natural logarithm of the water quality data, and 4) optimized curve fitting of a theoretically derived exponential model for the relationship between exoatmospheric reflectance and the water quality data. Two different solar spectral irradiance curves and an orbital eccentricity correction factor are tested using the exponential model. Results suggest: 1) Remote sensing from space-based platforms can provide meaningful information on water quality variability; 2) an exponential model best characterizes the relationship between the satellite data and the water quality measures investigated; 3) slight differences result from using the solar curve proposed by the World Radiation Center (as opposed to the NASA standard); and 4) predictions based on optical measures of water quality, rather than measures of the weight of particles in the water column, are slightly better when using Landsat MSS data.

Remote sensing of suspended sediments : the lake Chicot, Arkansas project

Abstract Landsat-MSS satellite data and corresponding water quality measurements of suspended sediment concentration for Lake Chicot, Arkansas, were used to evaluate several possible models For the relation between these two data types. Satellite data were converted to physical values of radiance and reflectance using both the NASA standard curve and the spectrum recommended by the World Radiation Center. Incorporation of an orbital eccentricity correction factor into the computation of solar spectral irradiance was also tested. Results of the analyses, which involved 310 observations suggest that a theoretically-derived expontential curve best characterizes the relation between exo-atmospheric reflectance and suspended sediment concentration. Based on the strength of the model relations and the range of data tested, it is concluded that temporal and spatial variability in the concentration of suspended sediments within lakes and reservoirs can be inventoried and monitored from space-based sensor systems.

Canopy attributes of desert grassland and transition communities derived from multiangular airborne imagery

Abstract The surface bidirectional reflectance distribution function (BRDF) contains valuable information on canopy physiognomy for desert grassland and grass–shrub transition communities. This information may be accessed by inverting a BRDF model against sets of observations, which encompass important variations in viewing and illumination angles. This paper shows that structural canopy attributes can be derived through inversion of the Simple Geometric Model (SGM) of the BRDF developed in this paper. It is difficult to sample BRDF features from the ground because of the discontinuous nature of the canopies and long intrinsic length scales in remotely sensed spectral measures (>10 m). A multispectral digital camera was therefore used to derive spatial multiangular reflectance data sets from the air and the SGM was validated against and inverted with these. It was also validated using 3-D radiosity simulations driven with maps of field-measured plant dimensions. The interpretation of the retrieved parameter maps (shrub density, shrub width and canopy height) reveals variations in canopy structure within desert grassland and grassland–shrubland transition communities, which are clearly related to structural and optical features in high resolution panchromatic and vegetation index images. To our knowledge, this paper reports on the first attempts to acquire structural canopy attributes of desert landscapes using multiple view angle data at scales less than 1 km. The results point to further opportunities to exploit multiangular data from spaceborne sensors such as the Multiangle Imaging SpectroRadiometer (MISR) and the Compact High Resolution Imaging Spectrometer (CHRIS) on the NASA Terra and European Space Agencys PROBA satellites, respectively.

Chlorophyll Measurements in the Presence of Suspended Sediment Using Broad Band Spectral Sensors Aboard Satellites

ABSTRACT Concentrations of chlorophyll-a in waters with high average annual concentrations of suspended sediment were measured in three lakes and compared with broad band Landsat MSS satellite digital data for 104 dates between December 1976 and August 1988. Concentrations of chlorophyll-a ranged from 0.3 to 211 mg·m−3 for 452 measurements. Concentrations of suspended sediment ranged from 1 to 867 mg·l−1 in the same samples. In general, chlorophyll-a concentrations were inversely related to suspended sediment concentrations. Radiance and reflectance calculated from the four MSS bands increased as a function of increasing concentrations of suspended sediment. Radiance and reflectance were inversely related to the concentration of chlorophyll-a, but the relationships were not statistically significant. This study indicated that the measurement of chlorophyll-a with broad band (100 nanometer) MSS data in waters dominated by suspended sediments is not effective since the detection of the increased absorption ...

Surface Water Quality Measurements of Lake Chicot, Arkansas Using Data from Landsat Satellites

ABSTRACT Thirty-three Landsat satellite multispectral scanner (MSS) scenes of Lake Chicot, Arkansas, collected between July 1976 and November 1979 were analyzed and compared with measurements of total solids, suspended solids and chlorophyll-a in the surface water. Total solids ranged from 117 to 908 mg l−1 with a mean of 234 mg l−1. Suspended solids ranged from 1 to 828 mg l−1 with a mean of 93 mg l−1. Chlorophyll-a ranged from 2 to 113 mg m−3 with a mean of 27 mg m−3. Radiance in milliwatts per square centimeter per steradian (mW cm−2 Sr−1) and reflectance in MSS band 6 (700–800 nm) had the highest correlation with total (r = 0.64 for radiance and 0.73 for reflectance) and suspended (r = 0.69 for radiance and 0.78 for reflectance) solids. Landsat MSS band 5 (600–700 nm) had the highest correlation coefficient (r = −0.55 for radiance and r = −0.57 for reflectance) with chlorophyll-a. Multiple linear regressions with the 4 MSS bands did not improve the correlations for either total or suspended sediment o...

Temperature sensitivity characterization of a silicon diode array spectrometer

Abstract High spectral resolution remote sensing devices are frequently used to quantify the flux of energy reflected from or transmitted through an optical medium. Their use requires careful calibration against a well-characterized standard. This study was conducted to characterize temperature sensitivity of a typical silicon-detector-based spectroradiometer, demonstrate the potential errors due to temperature effects, and present a methodology to correct for temperature-induced errors. Three Spectron Engineering SE590 units were independently evaluated under varying temperatures at three separate institutions. A procedure for correcting calibration coefficients (radiance/count) as a junction of temperature and wavelength was developed and applied. The evaluation showed that at wavelengths between 390 nm and 940 nm the calibration coefficients differed from each other by less than 5% among all ambient temperatures. At 1000 nm, the calibration coefficient decreases about 5% going from 25°C to 35°C and increases about 25% going from 25°C to 0°C. Wavebands below 390 nm responded chaotically to temperature. At any given wavelength above 940 nm the change in calibration coefficient value was a nearly linear function of temperature, an indication that a simple temperature correction can be applied. Calibration coefficients were linearly interpolated for each waveband greater than 940 nm at temperatures between temperature extremes imposed upon the instruments during the experiments. Linearly interpolated calibration coefficients were found to be within 4% of actual values. Users of silicon-detector-based spectroradiometers should be aware of potential errors in data due to temperature effects.

Spectral Measurements of Surface Suspended Matter in an Oxbow Lake in the Lower Mississippi Valley

ABSTRACT An 18-month study on Lake Chicot, Arkansas, has shown that spectral reflectance can be used to estimate the concentration of suspended solids in the surface water. Wavelengths between 700 and 900 nm give the best estimate of the concentration of suspended solids. This study shows that it should be possible to estimate the concentration of suspended solids in the surface water of Lake Chicot using remote sensing technology. Thus Landsat images, aerial photography, or sensors mounted directly over the water surface transmitting data could give a reservoir manager valuable data about suspended solids concentration that would be useful in making decisions on the management of water inflow to a lake or reservoir to control water quality.

Computer Mapping for Monitoring and Assessment of Surface Water Reservoirs

ABSTRACT A flow-through, water quality monitoring system, designed to evaluate the spatial heterogeneity of water quality in reservoirs (Grimshaw, 1987), was used to sample Lake Thunderbird, a reservoir near Norman, Oklahoma. Field testing was conducted to evaluate the operational feasibility of monitoring several water quality parameters along multiple transects, in a real-time manner. Results were processed and interpolated using two computer mapping systems and synoptic maps were generated. Qualitative and quantitative comparisons of the two mapping techniques were made. A synoptic map of turbidity, generated from Landsat Multispectral Scanner Band 3 (700–800 nm) data was compared to results obtained from both computer mapping techniques. With the exception of pH and turbidity, the synoptic maps provided similar estimates of lake area within selected intervals, but differed in the degree of detail revealed. Landsat-based turbidity estimates were higher than those measured directly in the littoral zone.

A device for the continuous measurement of algal photosynthetic response to light

Abstract A device is described for continuously monitoring the photosynthetic response to light of phytoplankton in eutrophic waters. Water is pumped from the system being monitored, and flows in parallel into 8 chambers that are placed in a light gradient. Dissolved oxygen is measured periodically at the inflow and outflow of each chamber. Solution of the dynamic mass balance equation for a well mixed system provides an estimate of net photosynthetic oxygen evolution as a function of light intensity. The last chamber is darkened with opaque plastic thereby providing a continuous estimate of community dark respiration. The assumptions made in design of the system are verified by tracer studies. The utility of the system is demonstrated by comparison with in situ incubations, and by results of monitoring phytoplankton growth in turbid waters.