Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER) is a Japanese sensor proposed to NASA EOS-am platform and Thermal Infrared Radiometer (TIR) is one of subsystems. ASTER TIR and Thermal Infrared Multispectral Scanner (TIMS), NASA/JPL airborne sensor, are unique because of their capabilities of multispectral and high spatial resolution observation of the earth surface in thermal infrared region.
In this parer, the applicability of the split window technique to TIMS data was discussed. The split window technique is a surface temperature estimation technique widely applied to AVHRR data for global sea surface temperature retrieval.
First, the effects of approximations used in this technique were examined. After that, computer simulations using LOWTRAN7 with several model atmospheres were carried out to investigate linear relations between surface and observed temperatures. These results indicate that TIMS Ch. 1 and 3, and 5 and 6 combinations are suitable for the split window application compared with other combinations.
A technique to determine coefficients of the split window equation which fits local atmospheric conditions was also proposed. This technique uses one base model atmosphere and several different relative humidity profiles in the simulations, and the equation can correct effects of local variations of water vapor content from the base atmosphere. Linear relations between simulated temperatures were significantly improved because atmospheres used in the simulations were identical except their humidity profiles. As a result, it can be said that the split window technique is applicable to TIMS Ch. 1/3 and 5/6 combinations within. these simulation conditions.
These split window equations were experimentally applied to TIMS data acquired over jasper Ridge, California. Though the atmosphere at jasper Ridge had less water vapor than Midlatitude Summer (MLS) model, the split window equations based on MLS model were able to correct the effects of this atmosphere properly. The effects of spectral variation of surface brightness temperature on the split window application were also found.

View full abstract

For three types of the estimation functions for sea surface temperature by the split window method, the error statistics were described in an unified manner by using the statistics of the validation match-up data set. The mean of sqnared errors is described as the sum of the residual variance in the regression function and the squared difference between the estimared values by the specified function and the regression function. The error variances were compared among the estimation functions, and those results were confirmed by the simulations using the Mutsu Bay match-up data set of NOAA-9/AVHRR.

View full abstract

An integrated data set composed of multi-sensor data (VTIR, MSR, MESSR and AVHRR) from MOS-1 and NOAA satellite combined with the observation data of sea surface temperature (SST) by ocean data buoys was developed for the purpose of the study on SST retrieval from satellite data.
The most important aspects for the data set are accuracy and easiness in the comparison of satellite data with sea truth data. The data set was developed by creating sub-images in which the image centers always correspond to the locations of the four ocean data buoys fixed at the oceanic areas around Japan by Japan Meteorological Agency. From the continuons measurement of SST by the buoys, the sea truth of SST can be estimated accurately when a satellite passes over the buoys. As the result, the precise evaluations for the algorithms in SST retrieval from satellite data are expected to be achieved.
Total four kinds of data sets were developed and some of the data sets were preliminary evaluated in order to verify the basic characteristics of MOS-1 data in SST retrieval. A remarkable improvement of the accuracy in SST retrieval with the combination of VTIR and MSR was found from the preliminary evaluation.

View full abstract

Heat islands of the cities in the Kanto Plain are recognized in the LANDSAT Thematic Mapper (TM) channel 6 image in assending mode (Path : 206/Row : 209) which was taken in 14/Aug./1984. The purpose of this study is to clarify the relationship betmeen the heat island intensity and the scale of urban area using the satellite image.
TM image is superimposed on the land use mesh map (KS202) in the Digital National Land Information of the Geographic Survey Institute, Japan. As a measure of the scale of the urban area, four indices are selected. They are the population density, population and the area of the Densely Inhabited District (DID), and the area of building site A (category 7) in the mesh map. Heat island intensity is defined as maximun difference in the digital number (DN) of the TM channel 6 between the building site A (category 7) and the paddy field (category 1), which is selected as a representative of suburban area. By using the mesh map as a mask on the TM image, heat island intensity is calculated for 35 cities in the Kanto Plain.
Heat island intensity increases with the increase in the scale of urban area. It is mutually related to the area of urban area rather than the population in the urban area. In the city surrounded by active vegetation, such as paddy in summer, heat island intensity becomes larger than that of the city surrounded by a small amount of vegetation, even though the scale of urban area are the same. Heat island intensity is not the index of the urban area itself, but the index of the area which includes the urban and surrounding suburban area.
Comparison of the thermal image with the Normalized Vegetation Index (NVI) image, which is processed from the MSS data in 31/Jul./1984, reveals the close relationship between the observed brightness temperature and the vegetation. Digital number in TM channel 6 decreases with the increase in NVI. It suggests that the vegetation lower the temperature of the terrain, and the distribution of vegetation strongly controls the thermal environment of the terrain.

View full abstract

The earth observation satellite, Landsat-5 launched in 1984, carried a high resolution imaging instrument called the Thematic Mapper. It is possible that the satellite occurs a high frequency attitude fluctuation caused by scanning mirror and high gain antenna drive, et al.. Fortunately, the magnitude of a high frequency attitude fluctuation was less than 30 meters of sensor spatial resolution of the TM imagery and didn't occur conspicuous geometric distortions in imagery. But, an Enhanced TM imagery of 15 meters spatial resolution of Landsat-6 scheduled to be launched in 1993, may be apt to cause attitude fluctuations due to the satellite bus. Therefore, it is necessary to develop an accurate attitude determination in regard to these problems.
There are two types of attitude sensors onboard the Landsat spacecraft: Inertial Measurement Unit and Angular Displacement Sensors. The IMU measures angular rate from DC to about 2 Hz. The ADS measures angular deviations from 2 Hz to 125 Hz. The geometric correction of TM imagery requires a time history from DC to the highest frequency at which a significant motion occurs about 100 Hz. To estimate the attitude is necessary to use an inverse filter with a compensated transfer function of these two sensors. However, some troubles would occur if an inverse filter is applied in straight forward manner. This paper discribes a high accurate estimation algorithm for attitude determination based on the crossover network model proposed by Sehn et al., and evaluates estimation accuracy using a simulated data. The estimation accuracy of 10^-2μ rad order at 0.01 Hz to 100 Hz is obtained. Our proposed algorithm may be applied to the attitude determination for the platforms of ADEOS, EOS, scheduled to be launched in 1996 and 1998, respectively.

View full abstract

An earth laser beacon observed from space looks like a point similar to a bright star. Thus the spot image of a laser beacon is very useful for calibration/correction of the earth's surface image taken by optical radiometers or cameras, since it corresponds to an infinitively small landmark whose absolute location and brightness are known precisely. We conducted experiments of tracking the MOS-1 satellite and transmitting a laser beam from a ground station at CRL to the satellite. An argon ion laser was used as the beacon and the images taken by the MESSR were analyzed for this study.
As the results of our analyses, the tendency of the MOS-1 location error obtained from optical tracking is shown. Then the geometric error of the MESSR earth images and the satellite's attitude estimated from two dimensional coordinates of the laser spot and the scene center, are shown.

View full abstract

Aerial photographs taken by using color films are utilized extensively and frequently in the environmental survey of ports and harbor areas. However, as to the human visual inspection and photointerpretation, their capabilities are limited, and it is fairly difficult to discern from the delicate densities of color photographs the turbidities and hydrodynamic phenomena in ports and harbors. Many items of effective information may conceivably be overlooked.
The present research is concerned with the digitizing of aerial photographs, treatment of them as multi-spectral data having three wavelength bands in the visual light region of red, green, blue colors, followed by subjecting the resultant data to image processing and statistical analysis. By carrying out such processes, it is intended to extract the potentialies inherent in aerial photographs and to male them serve furthermore as the means of environmental surveys in ports and harbors.
The results of the present research are summarrized as follows.
1) Although quantization of images ideally performed by histogram representation, very few data on red color components are available in the case of the information on surface water bodies. This leads to the deficiency of information therein, which requires alteration of the specification of films sensitometric characteristics.
2) False color image are helpful in visual inspection and photointerpretation. For the photointerpretation of turbidities in surface water bodies, a combination consisting of assigning respectively each of B, G and R color wavelength bands to each of R, G and B color image planes proved to be effective.
3) Eigenvalues and contribution factors, derived from the analysis of principal components, show the possibility of the intensive treatment of data. The score diagrams analyzing the turbidities of ports and harbor

View full abstract