In this parer, a temperature decrease by thermal interaction between the atmosphere and the land surface was analyzed in relation to the existence of sea breezes, extracting the distribution of land surface temperature on a single kind of land-use with Landsat TM and land-use data from National Digital Land Information. The land-surface temperature values in the coastal areas on the leeward side of the Japan Sea were found to decrease due to sea breezes horizontally and cross-sectionally regarding land-use of paddy fields or forests in Shimane Prefecture. Two spots were chosen to express the decrease in land-surace temperature due to sea breezes using the temperature difference between two points, one located in the leeward coastal area and the other inland.
The temperature decrease effect on leeward areas of the water related not only to wind speed but also the sea surface temperature and the atmospheric one. The effect was found to increase with the product U(T_a-T_w), which means the sensible heat, of the wind speed U and the difference between atmospheric temperature T_a and the sea surface T_w. According to the existence of this phenomena, the surface temperature is not only a fixed thermal boundary condition on the soil-plant-air system but another which needs to be considered from interaction with the atmosphere.

View full abstract

The present study was carried out in view of the industrial development and geographical changes of the Inchon area, near Seoul, Korea. The time series observations by Landsat have revealed that the salt fields in this area have remarkably decreased over the past decade, though there was almost no significant salt field reduction in the preceding four decades. The process of the salt field reduction on this area was displayed in the classified time series image from 1972 to 1988 with a view of making raster type GIS data files. The changes of coast lines were clearly revealedby overlaying old maps on the time series images. For Better visual demonstration of the changes of land coverage, these GIS data files were overlayed after rating with a special care. This procedure is probably available to make many types of thematic maps as well as GIS data base for various purposes.
It has been also found that the salt fields in the Inchon area have been being reclaimed as industrial sites, as ever seen in Seto Inland Sea area from the 1960's through 70's in Japan.

View full abstract

A method for image classification based on category proportion estimation is proposed. In this method, all pixels in a remotely sensed image are assumed to be mixed pixels (Mixels), and are classified to the most dominant category. Among the E, there exists unconfidential pixels which should be catetorized as unclassified pixels. In order to discriminate them, two types of criteria, Chi squere and AIC, are proposed for fitness test on the pure pixel hypothesis. Experimental result with a simulated dataset show an usefulness of the proposed classification criteion compared to the conventional maximim likelihood criterion and applicability of the fitness tests based on Chi squere and AIC.

View full abstract

In the temperature and emissivity (T/E) separation methods for ASTER thermal infrared multispectral data, influences of the atmospheric correction error as well as those of the empirical assumption error have tc be considered because no atmospheric profile will be observed simultaneously in the current plan. Thus, the sensitivity of T/E separation methods to the atmospheric correction error and the empirical assumption error is showed to be a function of atmospheric parameters, land surface parameters and wavelength and evaluated by LOWTRAN 7.
Considering the dependence of this sensitivity upon wavelength, a new suggestion to the application of T/E separation methods is introduced, which can reduce the influences of atmospheric correction error by the stepwise processings. The first step is to eliminate some channels relatively sensitive to the atmospheric correction error, then the second step is to calculate the temperature and the spectral emissivity of remained channels. This step is based on the empirical assumption on the emissivity of these channels. The final step is to derive the spectral emissivity of the eliminated channels using the previously obtained temperature.
In the final part of this study, the effectiveness of this approach is evaluated in the typical T/E separation method called the normalization method. The laboratory spectra of various materials are used as model data. This evaluation demonstrates the advantage of this approach, while the necessity of validity check of empirical assumption is also indicated.

View full abstract

A non-contact and non-destructive method was applied to the estimation of volcanic ashes on the surface of soybean plant leaves using spectroradiometer.
In this paper, we found the most effective spectral band and experimental equations suitable for estimating amount of volcanic ashes (white ashes and black ashes from Mt. Sakurajima Volcano) piled on soybean plant leaves.
The most effective spectral index for estimting the white volcanic ashes piled on plant leaves (Y_W, g/m₂) was the value of (R_900nm-R_450nm)/(R_900nm+R_450nm). The regression equation was Y_W=244.Oe^(-4.60x)(X:dimensonless). The determination coefficient (r²) was 0.939.
The most effective spectral index for estimating the black volcanic ashes piled on plant leaves (Y_B) was the value of (R_800nm-R_450nm)/(R_800nm+R_450nm). The regression equation was Y_B=252.8e^(-4.22X) (X:dimensionless). The determination coefficient was 0.965.
The observed and the estimated values of the amount of volcanic ashes (white ashes and black ashes) piled on plant leaves were well distributed on the ratio line of one to one. The determination coefficients were 0.958 and 0.970, and the standard errors of prediction were 4.78 and 4.13 respectively.

View full abstract

The topographic distortions, especially fore-shortening and layover phenomena of the Synthetic Aperture Radar (SAR) images are discussed in this paper.
Firstly, for the triangle terrain, degrees of fore-shortening and back-elongation of SAR images in the case of plane-wave illumination and spherical-wave illumination are digested here.
And for the steep triangle terrain, layover and shadow regions are defined and analyzed. Layover and shadowing phenomena closely depend on the off-nadir angle of radar waves.
As a typical example, the image of Mt. Fuji obtained by European Remote Sensing Satellite (EERS-1) SAR with an off-nadir angle of 23 degrees, clearly shows layover phenomena. As an another example, the image of Mt. Fuji obtained by Japanese Earth Resources Satellite (JERS-1) SAR with an off-nadir angle of 35 degrees, shows fore-shortning (non-layover) phenomena.
Both cases are also simulated by a computer and the same results are verified.

View full abstract