Ryuzo Yokoyama

Sea surface effects on the sea surface temperature estimation by remote sensing

Abstract By referring to the sea surface temperature profiler buoy (SSTPB) data observed in Mutsu Bay, this study showed under calm and strong sunshine conditions, the vertical water temperature profile near the sea surface bends abruptly, and sea surface temperature detected by satellite remote sensing is not necessarily coincident to the bulk sea surface temperature. Besides the atmospheric effect, this effect causes another error in the estimation of sea surface temperature by remote sensing data known as the sea surface effect (SSE). As a sequel to a former paper, this paper is concerned with the investigation of the conditions which occur in the apparent SSE. Statistical analyses were directed to the total data set of SSTPB. The amount of SSE was evaluated by the water temperature difference between the uppermost surface and 1 m depth, and apparent SSE was identified to when the absolute value of the difference is larger than 0·5 °C. Apparent SSE was observed in the season from May to September. Its ...

DEM generation method from contour lines based on the steepest slope segment chain and a monotone interpolation function

In this paper, a method to generate a digital elevation model (DEM) from contour lines is proposed. The method is characterized by 16 search directions to find the steepest slope direction from a grid point to the nearest and second nearest contour lines, an interpolation along the steepest slope segment chain, an improved identification of slope grid points, and a monotone interpolation provided by a simple cubic Hermit function to interpolate slope grid points. Noticeable improvements are achieved in the generated DEM from the proposed method against the DEM produced by the Geological Survey Institute (GSI) of Japan.

Phase-variable canonical forms for linear, multi-input, multi-output systems†

Three types of system equivalent relations are introduced to unify existing definitions of system equivalence. Called α-, β- and γ-equivalence, their characteristics are examined mathematically and physically. Based on those definitions, two phase-variable canonical forma are developed for linear, multi-input, multi-output systems, resulting in a canonical form for control and a canonical form for observation. It is shown that a characteristic quantity called a stage sequence can be defined for a given system to uniquely determine its equivalent system in the canonical forms. The compact structures of these canonical forms are convenient representations of the mathematical and physical compositions of systems and for subsequent system analyses.

Texture synthesis using a growth model

A systematic method of gray tone texture generation is presented. The procedure is composed of two phases. The first phase is to generate a set of images having characteristic pattern structures. Called mother images, these are synthesized by repetitive applications of seed distribution operations, skeleton growth operations, and muscle growth operations. The second phase is to synthesize a set of gray tone textures from a mother image by applying specific probabilistie transformations which convert numbers in the mother image to gray tone values.

Air-sea interacting effects to the sea surface temperature observation by NOAA/AVHRR

Abstract Abstract. By combining the brightness temperatures by NOAA-9/AVHRR and the sea surface temperature by Mutsu Bay automatic marine monitoring buoy system, the total number of 390 match-ups was set up. The temporal and spatial coincidence in each match-up is within 30 minutes and one pixel resolution. Following to the split-window method, a regression function for the sea surface temperature estimation was calculated and its standard deviation of estimation errors was 0-59°C. The residues were carefully examined with respect to the sensor calibration data and the meteorological data at match-up collections. Then it was found that large errors appeared when differences between the air temperature and the buoy temperature were large. Those were estimated to be caused by the air-sea interacting effects. By removing the match-ups with larger errors, a selected data set with 334 match-ups was prepared and the SST estimation function was recalculated. The standard deviation of errors reduced to 0-34 °C.

Spectral-Temporal Classification Using Vegetation Phenology

In this paper we describe a multitemporal classification procedure for crops in Landsat scenes. The method involves the creation of crop signatures which characterize multispectral observations as functions of phenological growth states. The phenological signature models spectral reflectance explicitly as a function of crop maturity rather than a function of date. This means that instead of stacking spectral vectors of one observation on another, as is usually done for multitemporal data, for each possible crop category a correspondence of time to growth state is established which minimizes the smallest difference between the given multispectral multitemporal vector and the category mean vector indexed by growth state. The results of applying it to winter wheat show that the method is capable of discrimination with about the same degree of accuracy as more traditional multitemporal classifiers. It shows some potential to label degree of maturity of the crop without crop condition information in the training set.

Estimation Of Sea Surface Temperature Via Noaa-AVHRR Sensor: Comparison With Sea Truth Data By Fixed Buoys

Brightness temperatures observed by ch. 4 and ch. 5 HRPT data of the AVHRR aboard NOAA-9 were compared with in situ sea surface temperature provided by the fixed buoys in Mutsu bay in northern Japan. The total of 154 match-ups of the coincidence within 30 minutes and 3 pixels were screened out. The linear regression analysis w as applied to the t hree grouped data sets, i.e.. the total data, the daytime data and the nighttime d ata. The standard errors in b oth single and d ouble variate r egression functions were comparable to be a round 0.5t. but t he maximum residues w ere improved in the double variate regression.

Line noise extraction of thermal infrared camera image in observing sea skin temperature

A thermal infrared camera provides relevant data to observe fine structure of sea skin temperature distribution. The image is exposed to various noises. The authors have developed two algorithms to correct a strip-type noise caused by the scanning mechanism and an inverse shading-type noise caused by spatial inhomogeneity of detecting sensitivity. The first algorithm is based on the two dimensional Fourier transform, and the second one was based on a spatial weighting function. By applying to scanning mode images of MUBEX the authors could confirm the effectiveness of the algorithms.

MUBEX: Japan and UK Collaboration for Mutsu Bay sea surface temperature validation experiment

MUBEX (MUtsu Bay sea surface temperature validation EXperiment) is a Japan-UK joint research project for accuracy validation of sea surface temperature observed by satellite and investigating into the physical behavior of heat exchange at the ocean surface. The project started in 1995 with the term of three years. The authors describe the outline of MUBEX and introduce some data obtained.

Transfer function matrix of linear, multi-input and multi-output systems†

The transfer function matrix of linear, multi-input, multi-output systems is calculated by using the phase variable canonical forms suggested by Yokoyama and Kinnen (1973). The transfer function matrix is described by rational functions of the matrix polynomial, of which coefficient matrices are submatrices in the coefficient matrices of the canonical form. The partition is uniquely determined by the stage sequence of an originally given system. This simple description of the transfer function matrix will be used conveniently in general analyses of linear multi-variable systems.