The seasonal variations of sea surface temperature have been investigated by the thermal image of the satellite and compared with the sea truth data. In spring, an coastal 'front formed between the Kuroshio branch and the inland water was observed in the Bungo Channel. In addition, small scale fronts were observed in the Iyo Sea as well. The sea surface temperature of the central part of the Iyo Sea is recorded as the lowest in this season. In summer, the coastal fronts became unclear because of a predominant upswelling in the Bungo Channel. The temperature in the Suo Sea is the highest in the inland. The sea state in autumn is, in general, analogous to that of spring. The coastal front was formed in the Bungo Channel as in spring. However, the lowest temperature could be observed in the southern Suo Sea. In winter, the influence of the Kuroshio branch reached around the central part of the Iyo Sea and formed remarkable coastal fronts, while the Suo Sea is much cooled than autumn.

View full abstract

Optimum spatial resolution which makes the heighest classification accuracy is determined from spatial frequency components, spectral features of objects and classification method.
Since variance of pixels correspond to that in the feature space increases in accordance with improvement of spatial resolution, classification accuracy will be gotten worse in accordance with improvement of spatial resolution under the limitations of variety of objects and class categories.
On the other hand, classification accuracy get better in accordance with improvement of spatial resolution because of decreasing of a ratio of "mixels" which are pixels composing with plural class categories. Since aforementioned two effects contribute to classification accuracy multiplicatively, it seems that there exist an optimum spatial resolution.
First, in this paper, based on the relationship between variance of pixels and classification accuracy, classification accuracy for MSS images with various Instantaneous Field of View(IFOV) will be shown. In their connection, variance of pixel values for images with various IFOV will be clarified.
Second, assuming the shape of boundary line between adjacent categories is circle, relationship among IFOV, ratio of mixels and classification accuracy will be cleared under the supposition that the number of mixels equals to that of misclassified pixels.
Finaly, it will be also shown that aforementioned relationships and optimum spatial resolution have been confirmed by using airborne MSS data of Sayama district in Japan.

View full abstract

Images of Geostationary Meteorological Satellite (GMS) since 1977 through 1984 are inspected to elucidate its detection capability of eruption clouds in the field of view of GMS. During this period above, eruption clouds by 26 volcanic eruptions of 196 events in total are detected and the detection capability is about 13%. The lowermost of altitude and dimension of detected eruption clouds are around 5 km and 30 km, respectively.
It is difficult to find out small-scale and ascending eruption clouds at the initial stage of eruptions, but the sequences such as time variations of driftdirections and coverage areas of the clouds, and decay of eruptive activities are fairly well observed by analyses of the whole shapes of eruption clouds, altitudes and isothermal squares of the upper surface of eruption clouds. The thermal energy release during eruption periods is estimated on the basis of thermal energy release rate by Briggs's formula(1969) and the supposed duration-times of eruptions, and the results are approximately proportional to intensities of respective eruptive activities.
Further increase of detection capability and more precise observations of volcanic eruption-sequences will be realized by increase of image-taking frequency and application of higher resolution sensors.

View full abstract

This paper discusses the dependence of SAR image qualities on the operating parameters for spaceborne SAR systems. The subjects treated in this paper are:
-incidence angle considerations for SAR imagery with geologic mapping purposes,
-the relation between the signal-to-noise ratio of the radar-receiver output signal and SAR image qualities,
-the influence of the receiver output signal quantization upon SAR image qualities.
We have defined several parameters to characterize SAR image qualities and determined them as a function of SAR system parameters.
The derived results, summarized in tables and charts, will provide quantative data to radar studies employing radar image simulation, in which image qualities are generally assessed visually. The results can also be applied to investigate the qualities and limitations of actual SAR images.

View full abstract