ADEOS was successfully launched on 17, Aug. 1996 by National Space Development Agency. This satellite marked a new era of global change study using Earth observing satellites. Global change study requires a comprehensive knowledge of the Earth system. Eight sensors on board ADEOS observe atmosphere, ocean and land simultaneously. Unfortunately, ADEOS has stopped its operation on 30, June, 1997 due to the breakdown of its solar paddle. However, almost 8 months of global data sets have been collected before the ADEOS accident. Data from ADEOS will bring better understanding of the Earth system.
After the investigation, NASDA has submitted the final report on the ADEOS accident and its influence on the future plans to the Space Activities Commission on September 1997. According to this report, NASDA has shown (1) the relationship between the ADEOS accident and the following six satellite programs, ADEOS-II, COMETS, ETS-VII, TRMM, OICETS, DRTS and summarized the degree of its influence on these programs and the technical measures to be taken for them. (2) the summary of early results from the analysis on the data obtained during about ten months observation, including the resuls applicable to the research to elucidate the Earth environmental change. (3) the action plans in the near future, the result of investigation on the similar data distribution, the utilization of similar sensors and the substitute satellites/sensors. This paper describes some of early results from ADEOS data analysis and NASDA's action plans following this report.
A method for cross calibration of the mission instruments onboard same platform as well as a method for cross validation of the products derived from more than two mission instrument data are proposed. The methods are verified with the mission instruments onboard ADEOS satellite. The experimental results from cross calibration betwee OCTS and AVNIR show that better than 1.5% of caross calibration accuracy can be achieved while the cross calibration between ADEOS/TOMS and Earth Probe/TOMS shows that better than 1% of cross calibration accuracy can be achieved. On the other hand, the cross validation of wind vectors derived from ADEOS/NSCAT and ERS-2/AMI shows that better than 0.41 m/s of cross validation accuracy can be achieved while the cross validation of Sea Surface Temperature derived from OCTS and AVHRR shows around 5 K of systematic difference between them. Through these studies, it was found that improvements on the data quality and on the calibration accuracy can be achieved.
The cross validation and the in-flight calibration are carried out for the radiometric calibration of AVNIR and OCTS reflective bands at the Rogers (Dry) Lake in USA. These two sensors are on the same platform, ADEOS, and can acquire the image of same scene in same sun-target-sensor geometry simultaneously, therefore the calibration coefficients in the cross calibration can be obtained with small uncertainty. The OCTS calibration coefficients in in-flight calibration based on the vicarious calibration and the cross calibration show the difference of 10 to 20% from the previously reported ones, and the AVNIR and OCTS calibration coefficients in cross validation based on the cross calibration show the difference of 10%.
This is an interim report of an ongoing CAL/VAL study for the ADEOS AVNIR sensor which is being conducted by the ADEOS sensor team and working group (including PIs). In order to calibrate and validate on-orbit AVNIR sensor characteristics, ADEOS CAL/VAL Campaign experiments using AVIRIS were conducted in the western USA. AVIRIS observations from ER-2 aircraft correlative flights by NASA JPL were conducted over Rogers Dry Lake and Ivanpah Playa in California on February 28 and March 4, 1997 respectively. The Japanese AVNIR sensor team/WG and NASA JPL team successfully performed correlative field experiments in both test sites. This paper firstly describes the objectives and outline of these ADEOS CAL/VAL campaign experiment in the USA. A few of in-situ simultaneous measurements data using spectral radiometers, Sun photometers, sky radiometer etc. are then shown. Finally, the first results of preliminary analysis for these field experiments are presented. Estimated gain parameters of AVNIR Mu bands are presented for Ivanpah Playa and Rogers Dry Lake using a vicarious calibration method. Typical estimated values of PSF1/2 of AVNIR Mu bands without atmospheric correction are also presented. As the CAL/VAL study for the AVNIR sensor is still ongoing, these data are tentative and must be validated.
Using OCTS and NSCAT /ADEOS data, the Chlorophyll-a concentration (Chl-a) and Sea Surface Temperature (SST) response to wind stress (τ) was investigated. The divergence of Ekmann transport (Ediv) was calculated from τ as a substitute for Ekmann upwelling. The studied area is west coast of North and Central America, and the twelve weekly data was analyzed at intervals in the period from 3 November, 1996 to 30 March, 1997. In this paper, it was verified that increase of Chl-a and decrease of SST correspond to increase of Ediv off Tehuantepec Bay in the south of Mexico and off California.
This paper proposes a procedure how to determine aerosol characteristics by referring to both of radiance and polarization. Our algorithms come from an idea that aerosol characteristics can be estimated in terms of scattering behavior in the polarization field. At first it is shown that a heterogeneous grain model according to Maxwell-Garnett mixing rule as small water-soluble (WS) inclusions in an oceanic (OC) matrix is available to interpret ADEOS/OCTS and POLDER data observed over the Arabian Sea. Then atmospheric correction, which is based on radiative transfer process in an atmosphere-ocean model involving the retrieved heterogeneous aerosol model, is applied to ocean color data given by ADEOS/OCTS. Finally our atmospheric correction provides an expected chlorophyll map near the sea surface. It is of interest to mention that retrieval algorithms for atmospheric aerosols are improved by combination use of radiance and polarization.
Ocean Color and Temperature Scanner (OCTS) is a visible and infrared radiometer devoted to frequent global measurement of Chlorophyll-a (Chl-a) and sea surface temperature (SST). After a long break of the global ocean-color observation, OCTS reopened it since November, 1996. Initial check of the sensor and preliminary results of Cal/Val have demonstrated availability of the OCTS data for global ocean color research. This article introduces the OCTS sensor, its Cal/Val and its characteristics in terms of oceanography.
AVNIR is a high spatial resolution imager on ADEOS with four multispectral bands covering visible range (blue, green and red band) and near-infrared range, and one panchromatic band. It has high spatial resolution observation capability with 16 m for multispecral bands and 8 m for panchromatic band. AVNIR has also a multi-viewangle observation capability (pointing function) with 40 degrees from nadir. These two characteristics of AVNIR enables to produce high quality land cover/use maps and digital elevation models (DEM). Besides these two pratical products AVNIR is expected to produce scientific parameters including space reflectance and surface reflectance which would play an important role in assessing radiation and energy budget on the earth surface. Also as science data sets AVNIR is expected to produce different types of thematic maps including wetland map, vegetation map and hazards map. This paper describes the function and the role of AVNIR in the ADEOS science program, and also introduces the current status of AVNIR data production.
AVNIR is a visible and near-Infrared multispectral imager on ADEOS. AVNIR observes the earth surface with the spatial resolution of 16 meters covering the wavelength range of 420 nm890 nm with 4 bands. It has also one panchromatic band of 520 nm690 nm with the spatial resolution of 8 meters. AVNIR scans about 80 km swath width along the cross track, using the large lineararray CCDs with 5, 000 pixels (multispectral band) and 10, 000 pixels (panchromatic band). The observation area is limited because of narrow swath width. In order to compensate this disadvantage, the pointing capability acquires the wide range of target within +/- 40 degrees around the nadir. In this paper, on-orbit calibration results of AVNIR and some application analyses results will be described.
In this study, we proposed a new algorithm for estimating aerosol optical thickness, using satellite image data alone. The algorithm validation was made using ADEOS/AVNIR image data (taken on April 24, 1997) and the atmospheric truth data by the skyradiometer (Prede : POM-01). We found that the estimation errors in optical thickness were less than 0.04. The atmospheric correction for the AVNIR image was done and the resulting surface reflectance image showed many detailed features, compared with the original one.
The ADEOS/AVNIR has a pointing function in the cross track direction and enables to conduct stereoscopic observation. Using the stereo pair images, it is possible to calculate the elevation based on photogrammetric principles. In this paper, the procedure for generating DEM from stereo AVNIR images is introduced.
An algorithm to derive the effect of adjacent land (ocean) surface on the emergent radiation from the top of the atmosphere is proposed. The underlying surface is heterogeneous. Thus the algorithm considers the effect of adjacent pixels to target pixel on the emergent radiation. This paper is a supplement to our paper (Vol. 17, No. 4).
ILAS (Improved Limb Atmospheric Spectrometer) on board ADEOS worked satisfactorily during the period from November 1996 to June 1997 until the end of ADEOS operation. It provided huge amount of data regarding high-latitude stratospheric ozone layer both in the southern and northern hemispheres. The present paper aims at describing briefly the data processing algorithms and data processing status, and demonstrating some early results of the Antarctic ozone hole measurements. The ozone and nitrous oxide distribution show clearly the structures of ozone hole in an altitude-longitude cross section.
Earth-satellite-earth laser long-path absorption experiment was being carried out with the Retroreflector in Space. The RIS is a hollow cube-corner retroreflector with an effective diameter of 0.5 m which has an unique design having a curved mirror surface. Optical characteristics of the RIS were tested using a second harmonics Nd:YAG laser. The intensity of reflection from the RIS was analyzed with an ICCD camera by comparing the image with those of stars. It was confirmed that the RIS in orbit was working properly as a retroreflector. Spectroscopic measurement was carried out with the TEA CO2 lasers. Spectra of ozone were measured successfully with the method using the Doppler shift of return beam which is caused by the movement of the satellite. The measurement of ozone using the RIS was validated by simultaneous measurement with a laser heterodyne spectrometer.
A phase correction procedure for the IMG interferogram data have been developed. The first step of the procedure is to set the Zero Path Difference (ZDP) sift values of the interferograms for the atmosphere (dXa), blackbody (dXh), and the deep space (dXc) to that stored in the IMG Level 0 data. The second step is to find the dXa for which anomaly of the phases of the difference vector between the atmosphere and the deep space is minimum. The third step is to find the dXh for which the phases estimated for the original radiations from the atmosphere and black body are equal to each other. The final step is to shift dXa, dXh, and dXc by the samestep so as that the final phase interested becomes flat. Also studied were phase error effects on the calibrated spectrum and retrieved vertical profiles of atmospheric parameters such as temperature. The results show that the magnitude of the spectral error caused by the phase error depends on the incident radiation intensity at each wavelength, and that degree and the vertical region where the retrieved results are affected by the spectral change can be estimated from the weighting function analysis.
El Niño-A global weather phenomenon was observed since March 1997. Equatorial sea surface temperature (SST) anomalies (departures from normal) greater than +2.5°C were observed along the equator east of 110°W in June ; SST anomalies in the Niño regions in 1997 have been the largest August and September values observed in the last 50 years. NASA Scatterometer (NSCAT) aboard Japan's Advanced Earth Observing Satellite (ADEOS, Midori) continually observed the global ocean surface wind speed and direction from September 1996 to June 1997. These easterly winds began to weaken from March. Since then, weaker than normal easterly winds have been observed across most of the equatorial Pacific. Wind shifted to westerly in the equator west of about 140°W in June 1997. The intraseasonal variations of zonal wind component are important during the El Niño onset period.
Winds are the critical factor in determining regional weather patterns and climate. In winter, the winds over the Sea of Japan have great effect on the weather of Japan islands. In this paper, wind distribution over the Sea of Japan is analyzed by using wind data observed by NASA Scatterometer (NSCAT) aboard Japan's Advanced Earth Observing Satellite (ADEOS, Midori). Synoptic views of the wind field over the Sea of Japan show remarkable evidence of a land topography effect causing a convergence of the surface wind field during cold-air outbreaks. The Changbai mountains in the North Korea locates at upstream of outbreak winds, and the wind field is deformed by them over the western part of the Sea of Japan. Strong north winds and northwesterly winds of about 15-20 m/s are observed off Vladivostok and off the Korea Peninsula, respectively, and they converge while blowing over the Sea of Japan. A wind shadow, where the wind speed is less than about 9 m/s, is seen in the downwind of the mountains, extending more than 200 km. Numerical experiments using a three-dimensional local circulation model were performed to investigate the formation mechanisms of the outbreak-wind deformation. The results show that the simulated winds agree well with the NSCAT observed winds.
Total ozone data obtained by ADEOS/TOMS (Total Ozone Mapping Spectrometer) were compared with those by ground based observation. Both of the deviations were about 2%. ADEOS/TOMS data showed availability for Antarctic ozone hole and anomalous ozone depletion over the Arctic in 1997. We concluded that such high quality global total ozone data obtained by ADEOS/TOMS are necessary for analysis of ozone layer.
Huge forest fires occurred in the dry season of 1997 in Indonesia. The fire smoke spread over Kalimantan, Sumatra, Indonesia and Malaysian Peninsula. Forest fires (biomass burning) has been thought to be a significant source of ozone precursors such as carbon monoxide, nitrogen oxides, and hydrocarbons. There will be a significant production of ozone, which is one of the important greenhouse gases and plays an important role in tropospheric chemistry. EORC/NASDA has made observations of atmospheric ozone with ozonesondes and a Brewer spectorophotometer at Watukosek, Indonesia under cooperation with LAPAN and University of Tokyo. Analyses have been made using ozone data at Watukosek and total ozone observed by Total Ozone Mapping Spectrometer (TOMS) on the satellites Advanced Earth Observing Satellite (ADEOS) and Earth Probe. The vertical ozone profiles show that the ozone mixing ratio has been enhanced especially above about 4 km altitude in the troposphere. The ozone mixing ratio sometimes reached over 100 nM/M (nano mol per mol). Total ozone observed by a Brewer spectorophotometer began to increase in the first half of September. Total ozone over 275 DU was frequently observed during the last half of September and October.
ADEOS/POLDER(POLarization and Directionality of the Earth's Reflectance) is the first space-based sensor aimed to observe the polarization and directionality of solar radiation reflected by the Earth atmospheresurface system. POLDER instrument is a multispectral photopolarimeter consisting of a two dimensional CCD detector array with a wide field of view of ±51° and ±43° in cross-track and along-track directions. POLDER measures the polarized light at three polarization angles. As for the multi-angle observations, it has a capability of measuring the light reflected by the target with 14 directions. On the other hand, due to this variety of measurements, POLDER products are very complicated and intractable. All POLDER data are processed and distributed by CNES in France. This paper introduces an overview of POLDER level 1 products and algorithms for processing line from the Level 1 data to frame-images. Once the frame-image has been obtained, we can get valuable information of clouds, atmospheric aerosols, land surface and ocean.
This paper described the analysis results of the reflectance and polarization image data acquired by POLDER on board ADEOS satellite. The ADEOS/POLDER's reflectance and polarization image data at 0.865, μm over the Arabian Sea near Indian Continent, taken on Nov. 18, 1996, were investigated by using typical aerosol size distribution models, namely, Oceanic, Water-Soluble and Junge models. We made multiple scattering simulations for these models by assuming a tropical atmosphere. A single atmospheric layer model with an isotropic Gaussian type ocean surface (Cox-Munk model) was assumed in this study. The main results of this study were summarized as follows: 1) We found that Junge model with ν=4.0-4.5 and m =1.50-i[0.00.01] and Water-Soluble model can satisfy the observed reflectance data, as well as the observed polarization data by assuming the typical ocean aerosol optical thickness values. 2) Oceanic aerosol model was rejected on the ground that it failed to explain the observed polarization features. 3) Based on multiple scattering computations, the image construction for both reflectance and linear polarization was made, using the estimated aerosol optical parameters. Simulated images showed that most of characteristic features in the observed images can be theoretically reconstructed. 4) Furthermore, the ocean wind speed at the time of POLDER observation was estimated to be V =4.06.0 m/sec from the analysis of the observed reflectance data.
The polarization at 443 and 865 channels over the coastal zone using ADEOS/POLDER data is analyzed.The data used here are 2 scenes including India and 1 scene over the Indian Ocean taken on November 18, 1996, 1 scene over the Pacific Ocean taken on November 1, 1996, and 2 scenes including the Sea of Japan taken on April 12 and 13, 1997. From the polarization analysis of ADEOS/POLDER images used in the present study, the following results are obtained : (1) At 443 nm, the polarization is due to the scattering of light by atmospheric particles. (2) Optical properties of atmospheric aerosols over the Indian Ocean are similar as those over the Pacific Ocean at November, 1996 because the polarization (%) versus scattering angle on the principal plane in the Indian Ocean is almost the same as that in the Pacific Ocean. (3) Over the sea surface, minimum points of polarization degrees are in visible in the backscattering region on both sides of the principal plane. On the other hand, it seems that over the land surface minimum points of polarization degrees appear in the vicinity of the principal plane at the 443 channel.
Measurements of the radiance and degree of polarization and optical thickness of aerosol made by a portable multi-spectral polarimeter on the ship are presented. The radiance and degree of polarization and the optical thickness of the aerosol over the ocean were measured from the ship. Wavelength regions are the same as those of visible and near-infrared bands of POLDER and OCTS on board the ADEOS satellite launched in August, 1996. As a whole, the numerical simulation agrees relatively well with the measurements in the radiance and the degree of polarization at the scattering angle of 90°from the solar direction.
A muti-purpose field radiometer (MSR7000) was modified to measure the degree of polarization and radiance of the skylight either from the ground or from a ship. The purpose is to evaluate atmospheric aerosol characteristics using polarimetric technique.
AOTF is a solid state electro-optical device which acts as an electronically tunable spectral filter. The specific point of the device is that we can simultaneously obtain two diffracted beams perpendicularly polarized to each other. So we developed an imaging spectro-polarimeter employing a visible (450-700 nm) AOTF as well as a visible and up to near infrared (500-1, 000 nm) AOTF. This paper first presents the concept, configuration, performance of the instrument and, examples of laboratory as well as field measurements. Then advantages and disadvantages of the instrument are discussed when installed in such an artificial satellite as ADEOS.
An improved method for designing the Global Imager (GLI) on board the Advanced Earth Observing Satellite II (ADEOS-II) is discussed. The GLI Signal Simulator (GSS) was developed and used for the experiments to study the performance of the some GLI channels. This method allowed successful selection of channels from a objective, rational point of view. The expected standard products which will be obtained by using GLI data are also discussed.
An interferometric method for multispectral imaging has been considered to be a sensor in remote sensing of greenhouse gases from satellite platforms. This method, which we call imaging coherence spectroradiometry, retrieves multispectral images from the three-dimensional spatial coherence function measured by a simple volume interferometer. This interferometer is equivalent to a parallel two-dimensional array of usual Fourier transform spectrometers which are known to work well in thermal infrared regions. The principle of this radiometry and a specific example of the design of interferometer are demonstrated to show the capability of the sensor to conduct global observations.
The first images acquired by the rain observation sensors on the Tropical Rainfall Measuring Mission (TRMM) were introduced. They are the global TRMM Microwave Imager (TMI) image that indicates the snow and ice in the convection around the tropical area, and the precipitation radar images that show horizontal and vertical distributions of rain rate in the typhoon 28.