A model for landslide prediction is developed using land cover information obtained from a satellite multi-spectral scanner data and geographical information such as the lay of the land, the nature of the soil and so on.
In this study, the applicability of remote sensing data for this model, the position of the remote sensing data on this model, and the significance of vegetation index and reflection characteristics are investigeted.
The conclusion of this study is as follows.
(1)The effective bands of TM-data for the landslide prediction are band-1, 4, 5, 6 selected with the Quantification Method Type I. The usage of the infrared bands is assumed to be particularly effective for the landslide prediction.
(2)The clustering of reflection characteristics is defined and evaluated with the Quantification Method Type II using the four bands described above. The selecting method of the effective bands from TM-data is found resonable.
(3)Although vegetation index in deduced from some different data with Quantification Method Type II, the most effective vegetation index of the four indices cannot be decided for the landslide prediction. Therefore another study from different viewpoint is necessary for the selection of the most effective vegetation index.
(4)The landslide prediction map thus made up is successfully compared with the existing field condition. This map can be used practically for the landslide prediction.

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By applying the regression analysis, this paper investigated the relationship between the ground surface temperature observed by NOAA-AVHRR and various environmental factors such as elevation, albedo of ch. 1, albedo of ch. 2, vegetation index, cosy and latitude. y is the incident angle of the direct sun light to the ground surface. The test area was specified to Tohoku district, which is located in the most northern part of Honshu, Japan, and has the size of about 200 km × 600 km. Three mid-afternoon AVHRR images collected on April 17, 1988, June 12, 1986 and October 8, 1987 by NOAA-9 were used in the analysis. The sample points were selected at every 5 km distance, but points in the areas of water, snow and cloud, or with large amounts of data variation in their neighbor-hoods were excluded.
The elevation and the vegetation index appeared to be significant to all the three images, but other explanation variables were not consistent. The April image had the smallest data range of the ground surface temperature and the correlation coefficient remained to be 0.53. In the June image, the most effective variable was the vegetation index, but the two albedos were comparable to this. Its highest correlation coefficient was 0.85. The October image showed the highest correlation coefficient as 0.84, and the latitude was the most important variable. Large positive residues appeared in inland basins where the vegetation index are not so high, and large negative residues appeared in coastal regions which would be affected by sea wind.

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By using a satellite data set and operational in situ measurements of snow, we produced a new data set to develope a detection scheme of snow in Japan using the satellite data. N-LAND database, created from NOAA-HRPT data, and AMeDAS observation data are combined to produce the data set. A case study of the snow detection made for the Tohoku area on 15 February, 1989 using the data set, shows that, with respect to the presence of snow, 96.4% of the cloud free observation points are judged right by a simple threshold level of channel 1 of AVHRR/NOAA. The failed points are investigated in detail, and possible explanations of the failures are given.

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This paper describes of an introduction to the "Special Issue on Radio Wave and Remote Sensing". Sensing with microwave is superior to with optical wave as all weather sensor. The penetrability of microwave to opaque weather such as cloud and rain has been proved by SEASAT and other Satel-lites. The subsurface radar has successed to probe objects buried in deep underground. Japanese Satellite implemented microve sensors i.e. MOS-1 MSR and JERS-1 SAR, and planning TRMM and ADEOS are also introduced in this Special Issue.

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Physical background of microwave remote sens-ing is introduced. Basic principles of microwave remote sensors (microwave radiometer, microwave scatterometer, microwave altimeter and microwave imaging radars) are reviewed. As for the microwave radiometer, the millimeter wave sounder is also introduced. In addition to the conventional scatterometer to measure wind vector, the precipitation radar is shown as an example of three dimensional scatterometer. As for the microwave imaging radar, both real aperture and synthetic aperture radar are shown. Especially, various types of synthetic aperture radars such as, interferometric SAR, polarimetric SAR, and scan SAR are introduced.

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NASDA conducted field experiment using Bread-Board Model (BBM) of MOS-1 MSR (Microwave Scanning Radiometer) for the water vapor, snow and others during 1981 FY-1983 FY. NASDA con-ducted MOS-1 airborne experiment using Engineering Model (EM) of MOS-1 MSR during 1984 FY-1985 FY. After the launch of MOS-1 (Feb. 19, 1987), NASDA conducted MOS-1 Verification Program (MVP) experiment using satellite, airborne data and others during 1987 FY-1989 FY. These experi-ments were conducted in collaboration with many participating organizations. As a result of these experiments, MSR data are found to be effective in monitoring water vapor, liquid water in cloud, ice concentration, ice distribution and snow depth. NASDA is a member of SAFISY (Space Agency Forum on International Space Year) and responsible for sea surface temperature and polar ice extent where MSR plays an important role. Ice concentration is measured under all weather condition. NASDA is developing AMSR (Advanced Microwave Scanning Radiometer). This is a candidate sensor for ADEOS-II which will be scheduled for launch in 1998. In this paper, outline of utility of microwave radiometer in earth environment monitoring is presented and several technical items are studied.

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Validation of geophysical parameters retrieved through iteration method by using the data of Special Sensor Microwave/Imager (SSM/I) was made with the truth data, such as total water vapor content and rain amount measured at the weather station of Chichijima island in Japan. We compared wind speed derived from SSM/I data with that observed by ocean buoys of Japan and U.S. The characteristics of the current and planned microwave radiometers are discussed, including Microwave Scanning Radiometer (MSR), Advanced MSR (AMSR), SSM/I, and SSM/IS. To measure sea surface temperature, requirement for calibration on AMSR is also discussed.

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This paper deals with the present status of active microwave remote sensing for rainfall measurement from space by rain radar. About 60% of the global rainfall is concentrated in the tropical region and it is presumably the principal driving force of the global climate system. This paper outlines the Tropical Rainfall Measuring Mission (TRMM) which is the first observation project with an active array rain radar in space. France is also planning the BEST project to observe tropical energy budget by measuring tropical rain and wind. Plans of rain radars on the manned space station of both USA (TRAMAR) and Japan (rain radar on JEW) are also introduced.

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Atmospheric gases have characteristic emission or absorption structures in millimeter-to submillimeter-wave range. Using the spectral features, various atmospheric soundings are in practical use; global monitoring of atmospheric temperature pro-files in the altitude range from 0 to 40 km is possible by using the bands of oxygen molacules in 50-60 GHz range or near 118.750 GHz. Monitoring of water vapor profiles in the troposphere is possible by using several bands near 183.310 GHz water vapor resonance and in 90-150 GHz range. Monitor-ing of upper-atmospheric ozone, water vapor, andmany trace gases, e.g. CIO originating in Freon gases, is possible by using ground-based short-millimeter-wave systems and satellite-borne or balloon-borne limb sounders operating in submillimeter-wave range. This report surveys these applications of millimeter-and submillimeter-wave sensors for atmospheric sounding.

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We have been developing a radio acoustic sounding system (RASS) which is a combination of an acoustic transmitter and a pulse Doppler radar to detect the velocity of acoustic wavefronts. The purpose of the development is to provide an operational tool to observe wind and temperature profiles unattendedly and continuously. The data obtained with RASS are useful for the researches of atmospheric phenomena relating to local weather and pollutant transportation. RASS can measure the temperature inversion layer with an accuracy of less than 0.3 K which is almost comparable with those observed with radiosondes. The development of RASS is now at a stage of practical operational use. In this report, measurement techniques of RASS and their capabilities and applications are described.

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The MU (middle and upper atmosphere) radar, established in Shigaraki in 1984, has been extensively contributing to the studies of the atmospheric dynamics. The fine time-height variations of the three components of the wind fields in the troposphere (below 10-15km) and middle atmosphere (10-100km) are observed with the MU radar, by using the clear air echoes caused by the refractive index fluctuations induced by the atmospheric turbulence. Various parameters of the ionized atmosphere in the ionospheric E and F regions (100-400km) can also be obtained by the incoherent scatter measurements with the MU radar. The versatility of the MU radar has enabled us to develop new observation techniques, such as RASS (Radio Acoustic Sounding System) for profiling the atmospheric temperature in the lower atmosphere, and the spatial and frequency domain interferometer for the measurements of the detailed structure of the atmospheric motions.

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A HF ocean radar is useful to observe sea states near coast. Okinawa Radio Observatory, Communications Research Laboratory has developed the radar in 1988, firstly in Japan. This article describes principles to deduce ocean current, sea surface wind direction and wave height from Doppler spectra detected by HF radar, and shows examples of them. Ocean current is calculated by Doppler shift of first order echo from Bragg frequency, and sea surface wind direction is obtained by the ratio of two first order echo intensities. But it is necessary to use second order echo for calculation of wave height. Comparison between sea states deduced by the radar and those by in-situ measurements shows good agreement.

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[in Japanese]

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