A numerical code of finite-difference time domain (FDTD) method to solve a light scattering by irregular particles has been developed. Using a standard 2nd order FDTD scheme and an absorbing boundary condition by a perfectly matched layer (PML), it is found that the light scattering features for size parameter x≤50 at wavelength 1.381μm for spherical ice particles have been successfully demonstrated by this FDTD code with spatial grid increment δ= 2./20. In the same numerical conditions, the light scattering calculations for hexagonal column aggregates are performed taking into account the particle's random orientation. The averaged phase function for the aggregate shows rather a flat angular dependence with no prominent peak features, which differs from the results of geometrical optics approximations for larger aggregate particles. Furthermore, a decrease of the side/back scattering efficiency and an increase of the asymmetry factor around the interference region of the particle's size are confirmed.
This paper represents the monitoring method of a carbon sink preservation activity for the global warming countermeasure using a high-resolution satellite image. The objective of this study is to assess the diffusion of organic farming in Papua New Guinea (P.N.G.) by applying the object-based image analysis to land-use classification. Slash-and-burn agriculture, also known as shifting cultivation, is commonly employed in P.N.G. With a low population density, forests have sufficient time to recover before being slashed and burned again. However, the significant increase in the population of P.N.G. accelerates the expansion of slash-and-burn fields, which causes decreasing of forests. Therefore, the prevention system against spreading the slash-and-burn fields should be established. Recently, the project that serves the prevention system and preserves forests has been practiced in Palmalmal village in P.N.G. This project promotes the organic farming so that the slash-and-burn fields could stand the recursive use. Moreover, the rice cultivation is diffused, which enables them to maintain the stable food, because rice could be stored for a long time. In this paper, we estimate the slash-and-burn field as one of the evaluating indices of the project. The object-based land-use classification is proposed to identify the slash-and-burn field. This preliminary examination indicates that the satellite image analysis is applicable to extract basic information for assessing the diffusion of organic farming, especially where the precise map is not available. We also discuss the estimation method of rice cultivating area.
Landsat ETM+images geocoded on the UTM coordinate over the World Geodetic System are now available. Although geometric accuracy of the images is much higher than that of Landsat TM images because of GPS based orbit information, there usually remains topographical relief displacement, which is significant for off-nadir part of the images over rugged terrain. This paper describes a method for ortho-rectifying the geocoded images. Direction and distance between a target pixel and nadir point are estimated using the geometric features of the actual data region in the images. Utilization of the digital elevation model geocoded over the Japan Geodesic System is also considered.
A balloon observation system aiming at taking remote sensing data at arbitrary date and hour and taking top views of the existing circumstances in detail has been developed. It was. approved that images almost corresponding to Band 1-Band 4 of Landsat TM with much higher space reso lution could be obtained except only for rainy and strong windy hours. For example, the size and space resolution of the image taken from the balloon altitude of 250 m are about 250 m×190m and about 9.7 cm, respectively. Application experiments to waterweeds monitoring, etc. were successfully performed.
Typhoon 200310 (Etau) caused concentrated heavy rain in the Hidaka district of Hokkaido, Japan, in August 2003, and large-scale landslides occurred in the region, especially in the Appetsu River basin (ca. 29, 000 ha). The landslides destroyed large areas of forest on hillsides, and a huge amount of timber was carried downstream, seriously damaging the economy and affecting people's lives along the river. To prevent secondary disasters and institute prompt measures for recovery of the watershed, we applied remote-sensing techniques using aerial photographs and satellite images to estimate the distribution and area of the landslides. The total area of landslides resulting from the typhoon was estimated to be 397 ha in the Appetsu River basin, constituting 1.7% of the total forest area in the basin. The total stem volume of timber destroyed by the landslides was estimated to be 57, 100m3.