We have built a pulse-compressed high-resolution radar for surveying polar ice caps and ice sheet. In experiments with this instrument at the Agassiz ice cap, radio echoes from the bedrock and internal layers measured with high resolution. The resolution of the radar in ice is about 1 meter. The greatest depth from which signals from bedrock were received was more than 400 meters and that from which signals from internal ice were received was about 200 meters. Such performances are suitable for generating data that can be used for detailed comparison between ice core analysis and radar data. This radar is expected to be an effective tool for revealing the three-dimensional extension of event-layer in the ice core and to give information about the scattering mechanism of internal echoes.

The worst month statistics of rain attenuation at 34.5 and 81.8 GHz along a terrestrial path of 1.3 km and rain rate were analyzed. The relation between the worst month percentage and the yearly percentage is independent of frequency. The results we obtained on the worst month statistics show a good agreement with Brussaard and Watson's semi-empirical model.

An airborne X- and L-band synthetic aperture radar system was developed by the Communications Research Laboratory and the National Space Development Agency of Japan in their joint project from 1993 to 1996. It is installed in the airplane, Gulfstream II. In both the azimuth and range directions, the resolution is 1.5 m for the X-band and 3 m for the L-band. Both SARs can make fully polarimetric observations. The X-band SAR has a cross-track interferometric function. In this paper we describe the SAR system, its ground processing system, and its performance. We also discuss motion compensation and interferogram quality.

Rain over ocean was observed by a real aperture microwave imaging radar. The radar has a function to record the received power on hit-by-hit base. Since the imaging radar has a wide beam in a plane perpendicular to the flight direction, rain echo and sea surface echo are overlapped in some range gates. In the overlapped range gates, a short-term received power fluctuations appeared. The correlation time of the fluctuation is shorter than those of rain and sea surface echoes. This fluctuation is thought to be due to an interference between rain and sea surface echoes. A computer simulation supports this speculation.

This paper attempts to use the polarimetric correlation coefficient for extraction of the polarimetric features of the urban areas and the natural distributed areas from Polarimetric Synthetic Aperture Radar (POLSAR) data. There is a possibility that the polarimetric correlation coefficient can reveal various scattering mechanisms of terrains based on the reflection symmetry property. In order to verify the capability of polarimetric correlation coefficient, we examined the behavior of this coefficient of the urban areas and the natural distributed areas with respect to the several polarimetric scattering models in the linear and circular polarization bases, and the difference of the polarimetric scattering characteristics between these two areas was derived. It was confirmed that the polarimetric correlation coefficient is useful to extract the polarimetric features from the actual L-band and X-band POLSAR data.

This paper describes a polarimetric feature extraction method from urban areas using the POLSAR (Polarimetric Synthetic Aperture Radar) data. The scattering characteristic of urban areas is different from that of natural distributed areas. The main point of difference is polarimetric correlation coefficient, because urban areas do not satisfy property of azimuth symmetry, Shh = Shv = 0. The decomposition technique based on azimuth symmetry can not be applied to urban areas. We propose a new model fit suitable for urban areas. The proposed model fit consists of odd-bounce, even-bounce and cross scattering models. These scattering models can represent the polarimetric backscatter from urban areas, and satisfy Shh 0 and Shv 0. In addition, the combination with the proposed model fit and the three component scattering model suited for natural distributed areas is examined. It is possible to apply the combined technique to POLSAR data which includes both urban areas and natural distributed areas. The combined technique is used for feature extraction of actual X-band POLSAR data acquired by Pi-SAR. It is shown that the proposed model fit is useful to extract polarimetric features from urban areas.