This paper describes a method of compiling the Kuroshio Current vector map from NOAA-6/AVHRR data, and aims at obtaining knowledge of the dynamics of oceanic currents and eddies. Through the compilation of the map, the following results were obtained. (1) A projection method of NOAA-6/AVHRR data to the 1:3, 000, 000 scaled map entiled "Japan and Its Surroundings" produced by Geometrical Survey Institute was worked out. This method allows for keeping a geometrical accuracy of 1% or less distortion at any portion in the mapping range of about 2, 000 x 3, 000 km2. (2) Continuous colour display from B&W imagery was developed. Oceanic currents and eddies can be recognized more effectively in this display than in conventional displays such as colour sliced ones. (3) The Kuroshio current vector map gives us the differences in the sea surface temperature over wide area, patterns of oceanic currents, and also sea bottom topography. All of this information is given on one photo. (4) A method of measuring current velocities using corresponding sea marks on time serial scenes was developed. With this method a measuring accuracy of 0.1 knots or less can be obtained. This method can be used to measure the angular velocity of oceanic eddies (this is attained by measuring twin current velocities on the sea surface at the eddy's center). Next, the following items of oceanic currents and eddies are discussed using some hydrodynamical model tests. (1) To strengthen the oceanic current chart provided by the Maritime Safety Board. (2) Oceanic eddies distributed in the surroundings of Japan Islands and their hydrodynamical features. (3) Observation of meandering in a very short period along the Kuroshio and its characteristics.
The airborne microwave rain-scatterometer/radiometer system operated at X-band and Ka-band was developed for the remote sensing of precipitation, especially rain from the airplane. This sensor system is the combination of the active microwave remote sensors, (i.e. the rain-scatterometers of X-band and Ka-band) and the passive microwave remote sensors, (i.e. the microwave radiometers of X-band and Ka-band). Airborne rain-scatterometers were developed as a first step for the development of the future space-borne rain-scatterometer. The total system is installed in the Cessna 404 and the remote sensing of precipitation is performed from the top of raining area through clouds. Flight experiments of more than 80 hours were perfomed in June, July and October, 1980 and in June, 1981. Date recorded in magnetic tapes are analyzed by the ground-based computer. An outline of airborne microwave rain-scatterometer/radiometer system is introduced. The sensor system in the flight experiment is shown with the example of measurement result. Some examples of preliminary data analyses are also discussed.
Remote sensing is regarded as a potentially effective data source for the measurement of water quality and for the environmental evaluation of water .bodies. In this paper, the water quality measurement by LANDASAT multispectral scanner data is described. Discussion emphasizes the estimation of the model for water quality measurement as well as the evaluation of path radiance and transmittance in the atmosphere. First, the path radiance and the transmittance were evaluated based on the linear regression analysis between the LANDSAT MSS data and the radiance data measured above the water surface. Next, the model for estimating water quality was derived based onthe linear regression analysis between the water quality parameters monitored on the lake and the LANDSAT MSS data after the atmospheric correction utilizing the evaluated path radiance and transmittance. The transparency and the suspended sediment concentration were mapped from the LANDSAT MSS images by the estimated model.
This paper firstly describes the principles of SAR(Synthetic Aperture Radar) imaging, i.e. resolution concept, frequency pulse modulation, pulse compression and Doppler effects. In the real aperture radar systems, the azimuth resolution depends on slant-range, wave length and antenna length, therefore it is greatly limited by the sensor itself. On the contrary SAR can achieve much higher resolution by storing observed signals and processing afterward. Secondly the analytical expression of transmitted and received signals is studied, and the digital processing of them to reconstruct SAR images is also theretically treated in detail, in terms of both range and azimuth directions, as one of compression problems of two-dimensional impulse response which is reflected from a point target. In this paper, matched filters in frequency domain are described along with some detailed evaluation of them. This processing is mainly consists of 4 steps, (1) holographic data generation, (2) real-complex data conversion, (3) range compression and (4) azimuth compression. In addition to the azimuth compression, multilook images are stacked to reduce the speckle noises which appear in reconstructed images because of the coherency of microwaves used. As an actual example, a two-dimensional impulse response generated by computer with SEASATSAR parameters was successfully compressed to a sharp single impulse. Finally a SEASAT-SAR image around LOSANGELS is reconstructed to show the validity of the digital processing presented by the authors.