Recent aggravation of the problems related to the outflow of the eroded silty red- soil from the Okinawa Island and its subsequent deposition on the coral reef needs more comprehensive and quantitative methods to analyse their actual situation. For this purpose, in the present paper, a new methodology mainly based on LANDSAT/TM data has been developed for the analyses not only of the islands as the source area of the red-silt but also of the surrounding coral reef as the deposition area of the silt.
Although there have been no attempts to detect the information of the deposition on the seabed from LANDSAT/TM data, the present study has succeeded in that by using the visible light band data and by developing a new data processing technique derived from the light transmission and reflection theory. For the analysis of the land area, LANDSAT/TM-based NVI (Normalized Vegetation Index) has been found to provide the information of the land covering rate by vegetation.
Finally, the interrelationship between the source-related factors in the island area, such as precipitation and land slope as well as the land covering by vegetation, and the deposition of the effluent silt on the coral reef area has been examined by using the quantification theory of type II. The result of the analysis shows that among these factors the covering by vegetation is the most influential factor on the red-silt outflow and its deposition on the reef.

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The split-window method is known as an effective sea surface temperature estimation algorithm by using NOAA/AVHRR data. Two fundamental structures are presently used for the purpose, i.e. the double varible function and the split-window function, but their coefficients derived from the regression analysis are empirically known to be almost equal. The similarity of the coefficients was investigated mathematically. It is shown that the similarity comes from the data statistics specific to the split-window method, i.e., the comparable ranges of the sea-truth temperature and the satellite brightness temperatures, and the high correlation coefficients between them. The variations of the coefficients were observed by the simulation using the match-up data set collected in Mutsu bay.

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Importance of conversion from digital numbers of remote sensing data to physical units has been stressed these days. For instance, the Log Residual method was proposed to relate digital numbers to reflectance patterns. However, the apparent spectral pattern given by the Log Residual method is not similar to the real reflectance spectrum, if this method is applied to the which contain one dominant cover type. The Least Upper Bound Residual method, which uses a spectral pattern with the maximum fluctuation as a reference, was proposed to avoid this problem. In this paper, we expose the problems of these methods and propose Gray Scale Log Residual (GSLR) method instead.
The GSLR method, which is a new technique to convert digital numbers to "apparent" reflectance patterns, is a modification of the original Log Residual technique in the following aspect ; to use reference pixel data which presumably exhibit flat (gray) reflectance pattern, e.g. cloud, halite and alluvial fan, in the visible to short-wave-infrared regions.
In this study, the GSLR method is evaluated by using cumulus cloud as reference pixels. Although the reference does not indicate a completely flat (gray) reflectance pattern, the GSLR method is the best of all the techniques in conversion from original data to apparent reflectance patterns.

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A method of generating Digital Elevation Model (DEM) automatically from system corrected SPOT data using at least 3 Ground Control Points (GCPs) of different elevations was developed. An area surrounding the Central Alps of Japan was selected as the test site and a pair of images (stereo registered images) of the test site which are registered to be available for computing the elevation, was produced using only 3 GCPs of different elevations. A method of correcting the elevations of the GCPs in producing the stereo registered images was proposed. The corresponding points between the stereo registered images were searched using an automatic image matching technique and three dimensional positions of the corresponding points were directly computed in the Earth Center Rotation (ECR) coordinate. The computing accuracy, examined by 36 check points, was 39.9 m, 71.7 m and 30.3 m (rms error) respectively in the direction of X, Y of an UTM and the elevation. The error of the elevation was 15.3 m and the errors of X, Y of the UTM were not changed when 3 GCPs of a same elevation were used. Many points of abnormal elevations whose elevations are abnormally different from their surroundings could be found in the first computed output, but most of them could be eliminated by post processings. A DEM generated by this method agreed generally very well with a DEM produced from 1 : 25000 scale geographical maps.

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The satellite remote sensing is prevailing in sea areas monitoring for environmental conservation since the visible and near infrared bands of satellite data are sensitive to turbidity and chlorophyll. In previous studies on this subject, however, the effect of the surface waves on the brightness values has never been considered so far. If the brightness values of the visible and near infrared bands are greatly enhanced by the surface waves, its effect should be detected and eliminated from the apparent values not to make confusion.
The authors have examined the MOS-1 MESSR data containing the areas with probable effect of the surface waves, which are extended widely enough to classify, and proposed a definition of the surface waves factor using the statistics on the brightness values.
We carried out the unsupervised classification by Histogram Overlay Method (HOM) on the basis of this definition and compared with the results by conventional cluster analysis. The areas with effect of the surface waves were discriminated from the turbid areas only when the HOM was applied. In addition, its effect was more pronounced in the near infrared band.
The effect of the surface waves on the reflection intensity of the sun light was investigated experimentally and theoretically. It was shown that the strongest reflection intensity is observed by satellites in summer when the incident angle of the sun light becomes the highest and when the direction of the wind is south-southeast, i.e., the same direction with the sun light.

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Mission Data Transmitter (MDT) Fl system functions were checked out on March 3 and F2 system functions were checked out in the Optical Sensors (OPS) checkout. On March 18 images were transmitted in the two-wave transmission mode and operations were confirmed to be normal. In off-line evaluations, the effective isotropic radiated power (EFRP) was checked over the entire area visible in Japan and the values found to exceed the standards.
Mission Data Recorder (MDR) functions were checked out on March 2 and the recording and play back time satisfied the standards off-line evaluations were used to check the bit error rate and the values were comfortably below the standard error rate 10^-6.
For OPS, first the operating restrictions were checked. The cooler's cooldown time was 15 min-utes (within 20 minutes as the spec.) and the restart interval was 73 minutes (within 90 minutes as the spec.). The shortened prep time for Short Wave Infrared Rediometer (SWIR) photography will greatly increase the operational effectiveness. In optical calibration tests, the lamp optics were radiated at all bands and all pixels, and the sensitivity was checked.
Data collected in orbit and thermal vacuum test data were compared and matched well, indicating that system changes caused by the launch are minor enough to ignore. Quantitatively evaluated pixels in particular, matched to within 1 LSB. When it is considered that images were recorded/replayed with the MDR and sent to the earth by the MDT, both OPS sensitivity and transmission system performance were within normal prameters.
In electrical calibration tests for each item, results were analogous to those described above. In image tests, the following categories were evaluated for the images captured:
[1] existence of noise and blooming.
[2] differentiation of sea, land and clouds/appropriateness of output levels, and
[3] sensitivity evaluations.
Data was evaluated qualitatively and quantitatively for those items. Results showed that output for all bands and each type of subject was optained and output levels (sensitivity) were normal. Overall, the above results indicated that the OPS easily satisfied the development specifications and that characteristics and performance base-line data for input at ordinary operation stage were obtainable.

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JERS-1, launched in February 1992, is the first Japanese satellite dedicated to supplying of data for practical earth resources applications. ERSDIS, the image processing that is being developed in ERSDAC under sponsorship by MITI, is composed of 3 main subsytems : PRS for performing of basic image processings and management of data storages, ALS for making of standard products and support of R & D activities, and DRS for data retrieval and product ordering. In principle, most of routine works related to user services would be performed on the semi-automatic basis, initiated by accesses from user terminals (word processors or personal computers) through data communication lines.

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Preliminary investigation on users' performance requirements to the sensors onboard Japanese Earth Resources Satellite (JERS-1) was performed using image data obtained in the initial evaluation stage. JERS-1 carries two observation sensors; Synthetic Aperture Radar (SAR) and Optical Sensor (OPS). The SAR uses L-band microwave with an off-nadir angle of 35 degrees. Compared with the SAR image obtained by European Remote Sensing Satellite (EERS-1) with an off-nadir angle of 23 degrees, JERS-1 SAR images have much smaller topographic distortions such as layover and fore-shortening that make photogeologic interpretation very difficult. The JERS-1 images of L-band exhibit a better capability to discriminate vegetation types compared with the C-band EERS-1 SAR and X-band airborne SAR images. Topographic texture patterns on the JERS-1 SAR images were quite useful to distinguish lithologic units.
The OPS has better ground resolution than LANDSAT TM and thus allows us more detailed surface observation. In the case of the normal gain setting, DN mean and deviation of OPS image data were small, because of six bits quantization and the large maximum input radiamce, which was chosen not to be saturated at even very bright targets. On the other hand, saturation occurs at bright targets in a few bands with low gain setting. Considering these situations, flexible and complex operation with frequent gain changes is highly desired. The SWIR data is expected to be useful for lithologic mapping but shows high interband correlation as expected. It is necessary to employ techniques to enhance spectral response patterns such as the decorrelation stretching and spectral index methods.

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