This paper proposes a microwave radiative tansfer model in snow cover on sea ice. The radiation propagating at an arbitrary depth in the snow layer is assumed diffuse radiation due to multiple scattering effect by snow particle based on observation. The model reasonably explains that the surface brightness temperature of the snow layer monotonously increases toward a symptotic value with increase in snow depth. Backward-scattering and absorption coefficients of the snow layer to diffuse microwave radiation were determined, applying observed brightness temperature. They are 1.16×10-3 and 8.27×10-3 cm-1 at 6.7 GHz, and 7.38×10-3 and 3.41×10-2 cm-1 at 18.6 GHz. Reflectivities of sufficient deep snow layer at 6.7 and 18.6 GHz were estimated from the model, and they are 0.068 and 0.098, respectively.
Patterns of total ozone distribution around typhoons were studied on NIMBUS-7 TOMS (Total Ozone Mapping Spectrometer) data, where the typhoon positions were determined by the typhoon track charts provided by Japan Meteorological Agency (JMA). Out of 185 samples on typhoon in the area 0-45N in latitude and 100-180E in longitude, in the period of four months, July through October (typical typhoon season), each year from 1979 through 1989, 80 typhoons showed definite signatures. Characteristic patterns were recognized in 243 samples. The patterns were roughly classified into 2 types : Central Dense (CD)-type and Spiral (S)-type. A CD-type has a dense ozone core on the typhoon position surrounded by a thin density fosse. An S-type shows a pattern, into which ozone dense stripes swirled. It is found that the S-type appears when a typhoon is coupled with a trough of a large scale pressure system in a westerly wind zone, and that the life time of the CD-type is comparatively short.
There are five cities on the southern foor of Mt. Fuji and the adjacent regions. Urban and industrial areas of these cities have greatly expanded during 20 years since 1970. The role of the forest vegetation in the suburbs of these cities has recently become very important to maintain the environment in good condition for human life, under the rapid urbanization. Environmental evaluation of Japanese black pice (Pinus thunbergii) forests which are distributed along the coast of the Suruga Bay and on a hill in the urban area is presented in this paper. The coastal pine forest spreads about 10 km long and 0.1 km wide, along the coast of the Senbonhama. The hill pine forest covers Mt. Kanukiyama, a hill in Numazu City, about 170 m above the sea level. False color images were produced by the multi dimentional level-slice method of the Landsat TM data based on the measurement of the spectro reflectance of the pine leaves. They show that decline in growth and/or death of pine trees occurred in both the Senbonhama forest and in Mt. Kanukiyama forest during five years since 1986. Ground-truth was carried out to make detailed analyses concerning the results of the false color images. It is concluded that, 1) decline of the pine trees in the coastal pine forest, recognized by Landsat TM data, is confirmed by the ground-truth, in which many declined old pine trees with thin leaves and a small number of the pine trees killed by the attack of destructive longicorn beetle (Monashamus alternates) were observed, 2) the pine forest of Mt. Kanukiyama had seriously destroyed by the attack of the longicorn beetle.
This paper describes the systematic analysis of the input power level, signal-to-noise ratio (S/N) characteristics and observation bandwidth for a high resolution earth observation system accommodated with charge coupled devices (CCD). The paper reports on the analysis of the S/N characteristics of the observation system using CCD considering the input power dependent noise. As a result of the analysis, the paper gives the diameter of the optical telescope for the required S/N value, and the examination results of the diameter of actual telescopes for satellite use. Accompanying the progress to higher resolution, the fine structure of the ground surface becomes to affect the input optical power. The paper reports on the input optical power characteristics in the case. of uneven ground surface and partial specular reflectance characteristics applying a simple surface model. The analysis shows that the signal dynamic range expands and the minimum signal level decreases in the higher recolution system with uneven ground surface. The paper also reports on studies for optimization of observation bandwidth considering the optical wavelength characteristics of the ground surface. The optimized observation bandwidth is analyzed to be expanded from reflection bandwidth in low S/N region.
The objective of this study is to propose a method to purify the training sample for the Maximum Likelihood Classification (MLC). Furthermore, we discuss whether purifying the training samples with the proposed method is significant or not for improvement of classification accuracy. The procedure of the proposed method consists of five steps as follows: STEP-1) Preparing the preliminary designated training data through the detailed ground truth. STEP-2) Classifying the preliminary designated training data by using MLC. STEP-3) Clustering the preliminary designated training data by using ISO-DATA algorithm. STEP-4) By using the separability as the index of the distance between classes, one to one correspondence is found between each classes acquired through the processing of step-2 and step-3 respectively. After that, the pixels which belong to the same class are selected to purify the training data. STEP-5) Classifying the pixels based on the class statistics of the purified training data by using MLC. The effectiveness of the proposed method were verified for the HRV data. The summaries of the results are as follows: 1) The proposed method can purify the training data automatically and effectively based on the statistical proceeding. 2) In comparison of the statistic values of the purified training data with those of the preliminary designated training data, the separability in terms of divergence was improved among all pairs of classes. Furthermore, the goodness of fit to the multivariate normal distribution was also improved. 3) The accuracy of PCC (Probability of Correct Classification) was increased to 92.6% from 84.9%. The proposed method for purifying the training data in this study is very practical and useful for classifying high resolution satellite data in case of using MLC.
A method of resolution enhancement for microwave active sensor such as marine radar is proposed in this paper. The resolution of an active sensor is determined by it's signal bandwidth and antenna beam width. Therefore, resolution enhancament generally requires to change the hardware of transmitter and receiver of the sensor or enlarge the antenna size. But this is usually limited in practical applications. This paper introduces a resolution enhancement method based on inversion method which can enhance the resolution of active sensors by signal processing without changing their hardware or enlarging their antennas. Deconvolution methods in frequency domain and spatial domain are described first. The effectiveness of these methods are shown by simulation. Then, some examples of resolution enhancement are applied to both marine radar and ground based pulse radar. The results of practical experiments show that these methods are effective and useful for upgrading radars by simply processing the received signals. The comparison between the two kinds of method in different domains shows that the processing in frequency domain is better than that in spatial domain when real time processing is required. A method about how to determine the optimum value of parameter α in revised Wiener filter is also proposed in this paper.