This paper describes the effective spatial information for increasing the classification accuracy in case of using SPOT HRV data. In this study, we deal with the spatial information, such as the texture feature, the enhancement image and the restoration image. The enhancement image was made with Laplacian operator, and the restoration image with MTF (Modulation Transfer Function). Nine cases, in combination with the spectral data and the spatial information, were executed. The results of this study are as follows : 1) It was found that the enhancement image and the restoration image are more useful than the texture feature for increasing the classification accuracy. 2) The enhancement image made with Laplacian operator considering the direction of 45 degrees is the most useful. 3) In this case, the Probability of Correct Classification (PCC) and the Division Accuracy are increased respectively from 88.1% to 92.2% and 91.0% to 96.5%. The Error Ratio considering Omission and Commission errors is decreased from 19.0% to 7.5%. 4) In comparison with the operation time (including CPU time), it takes respectively more than half an hour to make the texture feature (500×500 (pixels)) and the restoration image with MTF, but it takes only about 30 seconds to make the enhancement image with Laplacian operator. The efficiency of Laplacian operator is higher than the operator of making the texture image and the restoration image with MTF.
In an attempt to find out the characteristics of ozone distribution associated with the typhoon, analyses are made on the data of TOMS aboard NIMBUS-7 covering the south-western Pacific Ocean of the northern hemisphere. The analyzed data are for the months of July through October (typhoon season) and from 1979 through 1989. Following features are found on the characteristics of the ozone concentration: the pattern of ozone concentration associated with the typhoon is approximately classified into two types: CD (Dense in the Center) type characterized with higher concentration in the central part and S (swirl) type similar to rainbands of a typhoon. CD type is classified further into A- and B-types. A-type is characterized with a clear-cut high concentration core surrounded by area with lower concentration, while in the case of B-type this feature is not manifest. In this paper, we report that CD-A type ozone signatures on TOMS data can be roughly grouped into typhoon and non-typhoon signatures by some geometrical factors of the signature.
National Research Institute for Earth Science and Disaster Prevention (NIED) has conducted thermal observations of Unzendake Volcano using airborne MSS (VAM-90A) since Nov. 23 1990 through the period from initial stage to fierce eruptive activities of the volcano. The VAM-90A furnishes 8 spectral bands consist of 3 visible and near-infrared bands, 2 short-wave infrared bands and 3 thermal infrared bands to detect wide range of temperature from ordinary to highest at molten lava temperature for predicting volcanic eruption and watching eruptive activity. Through three times observation of the crater temperatures from Nov. 23 1990 to March 24 1991, consecutive temperature rise could be detected which indicated a precursor of increasing eruptive activity of the volcano. Thermal observation conducted on June 21 1991, when a lava dome was growing on the Jigokuato Crater and fierce pyroclastic flows had occurred frequently, could detect highest temperature of 475°C in a part of lava dome and high tempertures from 50°C to 243°C in the part of pyroclastic flow traces. Which are far high from the maximum temperatures ever observed by airborne MSS. It seems to be useful for precise recognition of the actual state of volcanic activity and estimating its perspective.
This paper describes an observation experiment of Volcano Unzen using an airborne imaging radar. The purpose of the observation is to confirm the potential of the microwave imaging radar for a practical use. Microwave images do not suffer from cloud or rain. This is a great advantage over the visible images. Volcano Unzen is very active and it is producing a lava dome and causes pyroclastic flows which killed people and damaged farms and houses, but Volcano Unzen was hard to observe because of rain cloud, especially in the raining season in Japan. We obtained thirteen images of Volcano Unzen. The best image was the one taken from west side of the mountain. The topography of Volcano Unzen was clearly shown. The active lava dome which has a dimension of about 100 m by 200 m was not clearly identified because of the relatively poor horizontal resolution of the imaging radar which was about 40 m by 40 m. The recorded data were corresponding to a pixel of 6.3 m by 15 m which is much smaller than the resolution of the radar determined by the pulse length and the antenna beam width. The oversampled data were averaged over eight data, which was very effective to improve the quality of the image without degradation of the resolution. Some problems for the practical use of the microwave imaging radar, including the resolution, aircraft flight conditions, were also pointed out.
The imageries of the volcanic eruption clouds (VECs) from Mt. Pinatubo, Philippines were taken at one hour intervals from 2240 ut (universal time) 14 June-2040 ut 15 June, 1991 by the Japanese Geostationary Meteorological Satellite Himawari 4 (GMS-4). These imageries were studied and indicated the following features. A disc-shaped VEC which is characterized by a visible gray area appeared in the vicinity of Mt. Pinatubo and covered an area ≈130 km in diameter in the visible image taken at 2240 ut on June 14, 1991. The VEC cast shadows on the surrounding white cloud (altitude : ≈16 km) due to typhoon and the VEC's equivalent blackbody temperature (Tbb) based on infrared digital image data was several degrees higher than the tropopause temperature (-83°C), thereby it is believed that the VEC injected into the stratosphere. The formation and dispersion of VECs repeatedly appeared in all visible imageries from 2240 ut 14 June-0540 ut 15 June, 1991. A gigantic disc-shaped VEC appeared, having its center ≈20 km west of the volcano in the 0640 ut visible image and covered an area ≈300 km in diameter. The VEC's Tbb was more than 10°C greater than the tropopause temperature. From 0640 - 0840 ut the VEC radially expanded against an easterly wind, spread out an area ≈600 km in diameter, especially 200 km upwind from the volcano and showed an increase in the VEC's Tbb. Furthermore, the area having a Tbb higher than -60°C continued to expand in all directions, especially up to 100 km upwind until 1140 ut, thus indicating that the volcano's activity continued. At 1240 ut the east edge of the VEC began to move westward, but the VEC continued to extend in the southward and westward directions until 1540 ut. Subsequently, the VEC's Tbb surrounding the volcano rapidly decreased and also the area having a temperature than -70°C further decreased, while the VEC enclosed by the -70°C isotherm gradually changed to the fan-shaped pattern which is dispersing westward from the volcano.
The objective of this study was to explore whether Landsat TM Data could be applicable to Tokyo Bay for mapping chlorophyl-a consentration. This study was investigated using Landsat TM Data and sea truth Data in Tokyo Bay on 6 August 1986, and 2 March 1987. As a result of study, We found that water quality information might be sampled from TM Data Band 5 and Band 7.