The seasonal spectral reflectance of tree leaves was measured by the use of a Shimadzu UV-2100 spectrophotometer with the integrating sphere in the region of visible and near infrared, from summer to autumn coloration period. In addition, the spectral reflectance of leaves was analyzed colorimetrically. Following results were obtained. 1) The spectral reflectance of green leaves was found to follow the previously discovered pattern. The spectrum had two major absorption ranges : in the region between 400 and 500 nm and in the region of 680 nm, which are similar to photosynthetic absorption range. Also another characteristic was the reflectance peak in the near infrared region, which was above 750 nm. During autumn coloration, the properties of the spectral reflectance of leaves changed. The spectral reflectance of the yellow leaf lost its absorption properties in the red region, and showed single absorption characteristics between 400 nm and 500 nm. The spectral reflectance of the red leaf showed absorption ranges between 400 and 500 nm, and again between 500 and 580 nm, the latter being caused by the appearance of newly formed red pigments. 2) The spectral reflectance increased in accordance with the number of layers of leaves. In the spectra of green leaves, the more the layers, the higher they reflected in the near infrared region. As for yellow and red leaves, the reflectance increased not only in the near infrared region but also in the visible region at the respective wave lengths for yellow and red. 3) Using the CIE (Commission Internationale de I'Eclairage) 1964 supplementary standard colorimetric system, seasonal color change patterns of leaves could be determined. Results of the present study suggest that these data are useful in the groundwork for further research on vegetation using satellite data.
Water balance on ground surface has been modified under the influence of changes in land covers. Potential evapotranspiration (Ep), which is one of the principal elements in a water balance equation, is calculated based on the method developped by Kotoda (1986). The changes in Ep are evaluated on the basis of bi-temporal LANDSAT images. The study area of 3767 km' includes western part of Tokyo Metropolitan area, Tama hills and Sagamihara upland. In Tama hills, many housing developments are distributed along several railroad lines. Calculated area is divided into 120×120 meshes, and Ep is evaluated for each mesh. Two LANDSAT MSS images, which were taken at Dec/14/1972 and Jan/23/1985, are used for land cover classification after geometric correction. Changes in land cover during 12 years are obtained for each mesh. Land cover mesh maps clearly show the enlargement of urban and residential areas, and the reduction of forested areas. Albedo (p) and the soil heat flux constant (Cr) had increased by 1.3% and 2.1% respectively, and the net radiation had decreased by 45 MJm-2 between 1972 and 1985. Annual Ep's for 1972 and 1985 are 592.6 mm/year and 573.9 mm/year respectively, and the change is -19 mm/year on the average. The decrease in Ep is large in Tama hill region, where the increase in residencial area, and the decrease in forested area are large. The relationship among 4Ep (mm/year), 4p (%) and 4Cr (%) is obtained by multiple regression analysis as follows, ΔEp=1.1-10.3Δρ-3.8ΔCr. The equation shows that the increases in p and Cr lead to the decreases of Ep quantitatively.
This paper describes optical design of the Retroreflector In-Space (RIS) for the Advanced Earth Observing Satellite (ADEOS), which is planned for launch in February of 1995. RIS is a cube-corner retroreflector for earth-satellite-earth laser longpath absorption measurements of atmospheric trace species such as ozone, CFC 12, carbon dioxide and methane. In the RIS measurement, a laser beam is transmitted from a ground station, reflected by RIS and received at the ground station. The absorption spectrum of the atmosphere is measured by scanning the laser wavelength. The density of the trace species are obtained by analyzing the spectrum. RIS has a single-element hollow structure and has an effective diameter of 0.5 m. The mirror shape for RIS was newly designed to optimize the intensity pattern of the beam reflected by RIS in orbit. A slightly curved surface is used for one of three mirrors forming the retroreflector to overcome the velocity aberration of the reflected beam. The effect of the curved surface on the intensity pattern of the reflected beam was investigated by a computer simulation. The parameters of the surface curvature were determined by optimizing the reflected beam intensity at the ground station.
Japan is known as the disaster island, various types of disasters occur every year in different parts of our country. The scale of disaster ranges from large to small, and in some cases these can be analyzed from satellite data with high resolution, but in other case aerial color photographs are more suitable for some cases. It is very important to establish disaster prevention measures in order to grasp land conditions under which a large scale slope hazards, such as a landslide may occur, namely to clarify the differences of land conditions at these risky areas. For this purpose, it is considered to utilize effectively aerial photographs taken befere and after the occurrence of landslide. Since the aerial photograph has geometric distortion, it is necessary to convert the aerial photograph into a digital image and to obtain an orthographic image by applying geometric correction. Furthermore, using the corrected image of land conditions, it is possible to analyze the specific features of land conditions of the area where slope hazard may occur by overlaying the two temporal images with the corresponding pixels. In this paper, the emphasis is placed on the image analysis method of aerial color photograph for the purpose of analyzing the difference of land conditions of the area where slope hazards occurred freouently. To explain the image analysis method more clearly, we attempted to make analysis using aerial color photographs of Jizuki mountain in Nagano Prefecture taken before and after the landslide occurence which took place on July 26, 1985.
The accuracy of radiance measurements of the MOS-1 MESSR (instrument No. 1) was evaluated by comparing the MESSR data with simultaneously collected ground based measurement data as follows. The upward radiances at the height of the MOS-1 were theoretically computed from the observed upward radiance at the ground surface using the atmospheric transemittance and the atmospheric path radiance. The transemittance and the path radiance were calculated from the data of the atmospheric turbidity, the vertical profiles of atmospheric temperature, the relative humidity etc. Those data were collected at the same time and place with the MESSR data. Multiple scattering theory was used for path radiance estimation, and the LOTWRAN6 code was used for the transemittance calculation. Then the upward radiance computed as above were compared with those measured by the MESSR. As a result, it was shown that the measurement accuracies of MESSR in band 1, 2 and 3 were very close to the planned sensor accuracy. However, the radiance derived from band 4 data showed the gain of about 0.7 against the the radiance derived from the ground based measurements. This suggests the decline of the sensor response in band 4 has taken place since the launch of MOS-1.
The accuracy of the sea surface temperature measured by the MOS-1 MSR has been degraded by both the rotated polarization due to antenna scanning and antenna sidelobes. This paper describes data correction methods for them. First, a simple function has been introduced to correct the polarization error due to antenna scanning. Second, an inverse filtering has been used to suppress the error due to antenna sidelobes in both simulation and real data obtained by the MOS-1 MSR. The MOS-1 MSR is a microwave sensor that rotates the main dish antenna with mechanically conical scanning. At the same time the observing polarization is also rotated by the mechanical scanning. Because sea surface brightness temperature depends on polarization, the rotation of the polarization causes measurement errors. The amount of the errors are estimated about 3 K at 23 GHz and 4 K at 31 GHz, respectively. The sea surface brightness temperature varies as nearly cosine or sine curves according to the rotated polarization. Then we made simple equations for error correction. Using the equations, the error correction for both 23 GHz and 31 GHz has been done and the errors after correction became within ±0.1 K. In order to evaluate the influence of antenna sidelobes on observed brightness temperature, we have calculated the brightness temperature on a simulation image. The results are as follows. If the main beam of the antenna is directed to sea and the antenna sidelobes look at ground, the sea surface brightness temperature are observed higher than true data because of the influence of the higher temperature of the ground. On the other hand if the main beam and the sidelobes are directed to land and sea area respectively, the land brightness temperature is observed lower than true data. The amount of the errors due to the antenna sidelobes are about 10 K higher at sea and 20 K lower at land. An inverse filtering method for the error correction has been applied to both simulation images and real data of the MOS-1 MSR. By this method we can correct more than 5 K and 10 K of the brightness temperature at sea surface and land, respectively. Finally, we discussed the effect of pixel fractionization for smoothing.
Microwave sensor can measure the ground objects through cloud cover and some rain. Using 23 GHz and 31 GHz bands of MOS/MSR, the authors developed a technology to observe the flooded area in Bangladesh. The observation principle is to estimate the submerged land from the decreasing ratio of the radiance emitted from the land when it is flooded with water. This measurement becomes possible because of the large difference of the emittance between water and solid land. Generally, the emittance from water is less than that from the solid land. This paper suggests a technique to measure the difference of two frequency radiance, 23 GHz minus 31 GHz, in order to avoid the disturbance caused by local variation of the ground physical temperature or caused by the change of atmospheric conditions. Although the emissions from the solid land varies with the moisture content, an assumption was taken here that the constant moisture level could be maintained in the tropical soil in Bangladesh in the rainy season. Thus, the measurement accuracy of water ratio to the field of view can be estimated with maximum error about 10% or less. Next, the sequentially observed MOS/MSR data for Bangladesh land during two years are analyzed by this technique. The results agree to the records of the hydrographs at three major rivers and at the lower stream regions.
In this study, we discuss the methods to manage the disaster information of slope land along the railway from the comprehensive viewpoint basing on the image analysis method of aerial photograph data already reported in this proceeding (1991, Setojima and Oyama) and utilizing the various information including related geographical information and map information. Main method used for conventional management of slope land long the railway has been the interpretation of aerial photograph. By this method, however, the volume of information to be collected is limited, and as the information thus collected is mostly expressed on a map, it has been too complicated to interpret and difficult to use. Due to the recent development of remote sensing technique, especially due to the rapid and technical access between remote sensing and GIS, more complex and comprehensive analysis have been realized by adding these techniques, to comprehensive remote sensing. As one of the methods to utilize these techniques for the prevention of disasters on slope land along railway and the management of railway facility, we tried to apply the image analysis technique using GIS functions for this purpose.
In this special edition, the present and future of remote sensing in the fishery are reviewed. The theme has such a broad spectrum that nine number of articles are edited to discuss following subjects. satellite ocean color remote sensing infrared survey on oceanic fine structure acoustic survey on fisheries resource original study on fishing ground formation coastal area environments case studies in the world fisheries forcasting system in Japan electronic systems on fishing vessels fishermen's intelligence of early ages The editor deeply thanks the authors for their generous contribution, and also hope multi disciplinary networks to be extended more comprehensively on these interesting thema.
Past and near-future satellite ocean color sensors, processing algorithms and related issues are reviewed. First, the paper excerpts the principle of ocean color remote sensing, showing the significance of satellite-derived pigment map in relation to fisheries application. After describing basic specification and function of Nimbus-7/CZCS which had been collecting useful data from late 1978 to mid 1986, the paper introduces the widely-used Gordon's atmospheric correction scheme. Problems in applying it to some portion of Japanese CZCS data set are identified. Thirdly, near-future satellite sensors, SeaWiFS (to be launched in August, 1993) and OCTS (to be launched in early 1995) are described in terms of technical specifications and functional enhancement compared to CZCS. The paper also lists out systematic requirements for operational use of SeaWiFS data in Japan.
Satellite infrared sensors can detect a lot of small scale phenomena at the sea surface such as streamers, warm tongues, frontal eddies and the others, which cannot be found out by old hydrographic surveys. But there remains some issues whether all of these phenomena are real one, because the satellite sensors observe just sea surface where the air-sea interaction is very active. So we have to distinguish that which kind of phenomena are real one or only illusion. In this paper, structures of some streamers and a warm tongue, which were observed on board the R/V Soyo Maru and by satellite NOAA AVHRR, will be presented. A cold streamer around the Kuroshio warm-core ring was derived from NOAA-9 AVHRR infrared images during June 8-13, 1986. The streamer was observed in late June, 1986. A cold low-salinity band, which was 2 to 20 km wide, more than 200 km long and more than 500 m deep, existed around the warm-core ring with geostrophic structure. On 15 May 1989, a warm streamer around the Kuroshio warm-core ring was visible in a NOAA-10 AVHRR image. The warm streamer was observed on board the R/V Soyo Maru during May 20 -22, 1989. The warm streamer had a structure deeper than 500 m depth. And also another warm streamer was observed in the warm-core ring. A warm tongue was detected in a NOAA-9 AVHRR image on 1 September 1987 in the northwestern part of the warm-core ring. A temperature section, which was observed during 5-21 September 1987, shows that the warm tongue was 300 m in thickness. A warm streamer was derived from a NOAA-10 infrared image on 18 May 1988 in Enshu-nada sea. Observations by only one section was conducted across this warm streamer during May 15-21, 1988. Warm water and cold water were recognized by turns in a temperature section. The geostrophic current relative to 1000 m deep in this. section suggests that an anticlockwise current around the warm streamer, which also coincides with the satellite image. All of these four phenomena detected by satellites actually exist and have deep structures. So satellite data are very useful for oceanographic studies.
Recent progress of underwater techniques for fisheries resources surveys is reviewed. The most important technique for the purpose is quantitative echo sounders. The technique is classified into three categories : estimation for individual fish which includes the echo counting method and in situ target strength measurement; estimation for individual school which includes density measurements in school; and echo integration method which is the most popular tool for abundance estimations. These methods are explained briefly. Some types of quantitative echo sounders are introduced and some advices for installing them are given. To perform a successful survey, some watching work is necessary, such as observing noise contamination and setting a threshold level to cut the noise. Future developments in this field are discussed and some powerful techniques such as the echo trace analysis for fish behaviour observation and the multi-frequency observation for plankton size and abundance estimation.
At present, Japan Fisheries Information Service Center (JAFIC) makes the Satellite Aided Oceanographic Condition Charts with NOAA AVHRR data and sends these charts to fishing boats in ocean. Making of the Satellite Aided Oceanographic Condition Charts significantly depends on human experts knowledges and experiences. It was turned out that the expert system is useful and effective for extraction of ocean conditions from sea surface temperature data. The JAFIC developed a discriminant prediction system of fishing ground formation using the NOAA AVHRR data (1982-1985). The discriminant prediction formula is as follows: F=0.32X1 +0.36X2 +0.88X3 If F>0, the fishing ground will be formed and F<0, the fishing ground will be not formed. Then the JAFIC applied this discriminant formula to the MOS-1 VTIR data. Besides, we investigated the relationship between fine structure of warm eddy and fishing ground using the MOS-1 VTIR data with assistance of aircraft data. We obtained interesting results as follows. (1) By use the simultaneous aircraft data, we know that many schools of sardine are distributed at the head of warm streamer. (2) It seems that the warm streamer is useful for the transfer of schools toward for the north.
Since LANDSAT-1 was launched in 1972, the satellite remote sensing and airborne remote sensing based on the analysis of high resolutional imagery which detects so many sea surface phenomena distinctly has become very popular in the field of oceanography and fishery. In this report, the author tried to investigate the capability of remote sensing by satellite and airborne using the data obtained in Japan and sevaral remarkable results were carried out as follows : 1. NOAA AVHRR data is recognized as very effective to monitor the flow pattern of Kuroshio Current. 2. LANDSAT MSS and TM data were considered as very useful to detect river effluent, coastal current, discontinuity line and hot efflux from power station. 3. MOS-1 MESSR and VTIR data were also recognized as very effective to monitor the sea surface phenomena as the interpolate data of LANDSAT and NOAA. 4. Airborne MSS data is concluded as very useful to monitor the environmental problem such as hot efflux and oil pollution in time-lapse observation.
Applications of RS (Remote Sensing) to fisheries oceanography are rapidly spreading to many sea areas in the world. Many of them, however, are not necessarily in higher level than contemporary methods, while the technology of satellites and sensors are being developing exceedingly. Authors analysed applicabilities of RS to fisheries oceanography and carried out case studies on the pursuance of them in various sea areas and also for different living marine resources. On the basis of the findings, authors consolidated results of investigations for long years and showed how those applicabilities were being pursued in major foreign countries. Through these aspects, international views for the technical cooperation or the needs/seeds-oriented research are expected.
The roles of the various environmental factors played in the success or failure of fishing operations, resources research and management have been discussed in many papers. Fisheries forecasting is one application of these natural rules to fishing industries. Among these factors, oceanographic conditions are most closely linked to fish resources and fisheries. These conditions can be put into two different categories, according to their shortand long-term implication. The methods and techniques to be employed in fisheries forecasting differ greatly by category. In Japan, short-term forecasting has been practically implemented. by the Japan Fisheries Information Service Center (JAFIC), a subsidiary organazation of the central government, in collaboration with national and local fisheries research institutes. And, for short-term forecasting analysis observations of sea-surface temperature made of satellite can be used for the services provided by JAFIC. On the other hand, long-term forecasting is carried out chiefly by the oceanographic and resources departments of the national fisheries research institutes in close collaboration with local fisheries experimental stations of prefectural government, over the entire coast of Japan. I present in this paper a review of the fisheries forecasting system currently employed in the coastal pelagic fish fisheries in Japan from both a technical and administrative point of view.
The use of electronics in fishing dates back to 1948 when fishermen first used the echo sounder in Nagasaki, Japan. In those days fishermen used to fish by their experience and human sense. For example, they knew from experience that they could find a school of sardines where the sea surface was bubbling up. This fish-finding technique based on the experience and human sense could be called "human remote sensing." Such an intuitional method could be successful once in a while, by chance, but on a rainy day the fishermen could not discriminate any "bubbles" on the sea surface. Then, the echo sounder (also called the "fish finder") appeared to replace the "human remote sensing." The authors believe the advent of the echo sounder that used ultrasonic waves marked the beginning of "electronic remote sensing." Since then, many fishing vessels adopted a wide range of electronic equipment. Today's typical fishing vessel is heavily equipped with the electronic equipment that would entitle her to be called an "electronic ship." This paper describes the latest electronic systems installed on fishing vessels. It also introduces how the equipment is used by fishermen. We expect the electronics for fishing will ever develop in the future.
Through the ages, Japanese fishermen have handed down a large volume of intelligence of sea, air, fish and their interrelation. The most interesting is of the stormy currents called Shikeshio. Near the capes, a strong current system is induced by atmospheric lows and often brings with it a big catch of yellowtail. In this article, the knowledge of Shikeshio is made revitalized as the sea and air truth for the satellite oceanography of the Kuroshio. Based on it, a deterministic eddy system is reasonably interpreted on NOAA imageries and its geofluid mechanics is uncovered. Some snapshots are also presented together with NOAA imageries and weather charts to document an exciting big. catch of yelloxtail at the Cape Ashizuri, that had resulted from an arrival of a strong low in the March of 1988.