Tasuku Tanaka

Calibration and Validation of the Ocean Color Version-3 Product from ADEOS OCTS

We present calibration and validation results of the OCTS’s ocean color version-3 product, which mainly consists of the chlorophyll-a concentration (Chl-a) and the normalized water-leaving radiance (nLw). First, OCTS was calibrated for the inter-detector sensitivity difference, offset, and absolute sensitivity using external calibration source. It was also vicariously calibrated using in-situ measurements for water (Chl-a andnLw) and atmosphere (optical thickness), which were acquired synchronously with OCTS under cloud-free conditions. Second, the product was validated using selected 17 in-situ Chl-a and 11 in-situnLw measurements. We confirmed that Chl-a was estimated with an accuracy of 68% for Chl-a less than 2 mg/m3, andnLw from 94% (band 2) to 128% (band 4). Geometric accuracy was improved to 1.3 km. Stripes were significantly reduced by modifying the detector normalization factor as a function of input radiance.

On a possibility to monitor seismic activity using satellites

Abstract Methods of satellite monitoring of different phenomena around the date of large earthquakes are evaluated and reviewed. A combination of satellite and ground-based monitoring will be evidently useful for the study of seismo-electromagnetic phenomena either directly connected with the radiation from seismic source or revealed from the radio sounding of atmosphere and ionosphere.

Solution of radiative transfer in anisotropic plane-parallel atmosphere

We solve the radiative transfer problem analytically in the anisotropic, plane-parallel atmosphere. Chandrasekhar formalized the radiative transfer process as a simultaneous, two-variable, non-linear, integral equation and obtained the analytical solution of the second approximation for the isotropic plane-parallel atmosphere. We obtain the second approximation for the anisotropic atmosphere, by integrating the first approximation multiplied by weighting functions which are products of the scattering phase functions. We truncate the second approximation and obtain the radiance at the top of the atmosphere as a quadratic equation with a logarithmic term in the optical thickness. We evaluate the second approximation of the radiance at the top of the atmosphere for Rayleigh scattering and the maritime aerosol atmosphere and compare them with both the exact solution and the single scattering approximation.

Earth observation program in Japan and its international cooperative activities

Abstract In Japan, the first experimental earth observation satellite, Marine Observation Satellite‐1 (MOS‐1) was launched on February 19, 1987 successfully by National Space Development Agency of Japan (NASDA). NASDA is now performing MOS‐1 Verification Program (MVP) in order to verify the usefulness of MOS‐1 sensor data. Japanese Earth Resources Satellite‐1 (ERS‐1), with its launching scheduled in early 1992, is under development as a joint program of Ministry of International Trade and Industry (MITI) and NASDA. Following the fulfillment of these programs, Japan is to pursue its next step earth observation programs. As a next generation earth observation satellite, NASDA plans to launch Advanced Earth Observing Satellite (ADEOS) in 1993. Moreover, a new earth observation program with Polar Orbiting Platform (POP) is now planned and coordinated among the Space Station Partners, namely, NASA, NOAA, ESA, Canada and Japan. Currently, NASA, ESA and Japan have their own platform launch plans in late 1990s. ...

Retrieval of Earth observation data in visible and near-infrared bands

Multichannel Earth observation data have been available to the science community since the launch of ADEOS. To retrieve several geophysical parameters, not one, we need multiple-band observation. The ADEOS satellite carried eight instruments that covered bands from ultraviolet to microwave. We have begun to analyze the spectrally wide ADEOs data, or multiple- instrument data, to seek new methods to infer crucial geophysical parameters. Satellites observed data in the visible and near infrared bands comprise radiation from molecular scattering (Rayleigh scattering), aerosol scattering (Mie scattering), water vapor absorption, and surface reflection. The separation of components is an important goal of satellite remote sensing retrieval. In this paper, we introduce the ADEOS satellite, its instrumentation, and the ADEOS SYNERGISM dataset. We will discuss the characteristics of the radiance received by satellites and show interesting data and properties derived from the ADEOS SYNERGISM dataset. We will also discuss further separation of the components that constitute satellite observed data in the visible and near- infrared bands.

Integration of Chandrasekhar's integral equation

Abstract We solve Chandrasekhars integration equation for radiative transfer in the plane-parallel atmosphere by iterative integration. The primary thrust in radiative transfer has been to solve the forward problem, i.e., to evaluate the radiance, given the optical thickness and the scattering phase function. In the area of satellite remote sensing, our problem is the inverse problem: to retrieve the surface reflectance and the optical thickness of the atmosphere from the radiance measured by satellites. In order to retrieve the optical thickness and the surface reflectance from the radiance at the top-of-the atmosphere (TOA), we should express the radiance at TOA “explicitly” in the optical thickness and the surface reflectance. Chandrasekhar formalized radiative transfer in the plane-parallel atmosphere in a simultaneous integral equation, and he obtained the second approximation. Since then no higher approximation has been reported. In this paper, we obtain the third approximation of the scattering function. We integrate functions derived from the second approximation in the integral interval from 1 to ∞ of the inverse of the cos of zenith angles. We can obtain the indefinite integral rather easily in the form of a series expansion. However, the integrals at the upper limit, ∞, are not yet known to us. We can assess the converged values of those series expansions at ∞ through calculus. For integration, we choose coupling pairs to avoid unnecessary terms in the outcome of integral and discover that the simultaneous integral equation can be deduced to the mere integral equation. Through algebraic calculation, we obtain the third approximation as a polynomial of the third degree in the atmospheric optical thickness.

Earth observing system of NASDA

Abstract Since the successful launch of Marine Observation Satellite-1 (MOS-1) in 1987, the National Space Development Agency of Japan (NASDA) has been operating, developing, and planning Earth observation satellite programs. Looking to the 1990s, our primary concern is “Global Change”. NASDA is now developing Geo-Stationary Meteorological Satellite-5 (GMS-5), the Japanese Earth Resources Satellite-1 (ERS-1) and the Advanced Earth Observing Satellite (ADEOS). These will be followed by the Japanese Polar Orbiting Platform (JPOP). In addition, NASDA is now conducting the Tropical Rainfall Measuring Mission (TRMM) in cooperation with NASA. This paper introduces the mission objectives of NASDAs programs and discusses how to conduct space-based observations for global change research activities.

Japanese earth observing systems in the 1990s

Abstract Since the successful launch of Marine Observation Satellite-1 (MOS-1) in 1987, the National Space Development Agency of Japan (NASDA) has been operating, developing, and planning Earth observation satellite programs. Looking to the 1990s, our primary concern is the “Global Change.” NASDA is now developing the Japanese Earth Resources Satellite-1 (ERS-1) and the Advanced Earth Observing Satellite (ADEOS). These will be followed by Japanese Polar Orbiting Platform (JPOP). In addition, NASDA is now conducting the Tropical Rainfall Measuring Mission (TRMM) in cooperation with NASA. Other countries have their own Earth observing programs for 1990s. All the Earth observing programs are summarized in Table 1.