A calibration load with specular-reflection absorbers for a submillimeter-wave radiometer is proposed, and the results of fabrication and performance tests are described. The load consists of a pair of flat-surface specular absorbers set at their Brewster angle giving polarization-independent performance. By the use of absorbers with specular surfaces, the electrical and thermal design for a hig-power reflection loss calibration load becomes easy. The obtained effective brightness temperature and coherent power reflection coefficient are 300 K and less than -60 dB, respectively, at frequencies between 624 and 650 GHz. The load has been used for the absolute calibration of the SMILES (Superconducting Submillimeter-wave Limb-Emission Sounder on the International Space Station/Japanese Experiment Module).
The present study shows an assessment of the equivalence between the four-component scattering power decomposition (4-CSPD) algorithms based on rotation of covariance matrix and coherency matrix, and the ambiguity in the rotation of these matrices. Theoretically, the 4-CSPD algorithms with rotation of the two matrices should be identical. In this paper, an experimental proof is presented to show the actual equivalence of the two algorithms using polarimetric synthetic aperture radar (POLSAR) data acquired by Phased Array L-band SAR (PALSAR) on board Advanced Land Observing Satellite (ALOS). An obscure point in the previous publications was also made clear. That is, there is ambiguity in minimizing the cross-polarized term in order to enhance the double-bounce scattering component by the rotation of polarimetric matrices. We analyzed how the results would be different if this ambiguity remains. The removal of this ambiguity optimally enhances the double-bounce scattering component.
The Advanced Land Observing Satellite (ALOS), which was launched in January 2006, ended its successful mission life in May 2011. The satellite had observed global land areas from space for more than five years and left us with a huge amount of data. The Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM), one of ALOS’s onboard sensors, was designed to generate worldwide topographic data with its stereoscopic, hig-resolution observation. The sensor consists of three independent panchromatic radiometers for forward, nadir, and backward viewing to produce a triplet stereoscopic image along its track. Each radiometer has 2.5 m ground resolution in its 35 km swath. We developed software to generate Digital Surface Model (DSM) data from the stereoscopic images for the Earth Observation Research Center/Japan Aerospace Exploration Agency (EORC/JAXA). The software fully supports the rigorous sensor models that are being applied to standard products. It generates DSMs in 10 m grid spacing using a unique image-matching algorithm developed exclusively for PRISM and then archives them scene by scene. We have processed more than 6000 DSM scenes of Japan and some specific sites that have their validations and research applications. These DSM scenes must be combined and interpolated onto the familiar geographic latitude/longitude grid for the final standard DSM dataset. This paper reports on the status of the archive of DSM scenes on all Japan land areas and the mosaicking algorithm, which combines the data into 1°×1° tiles, along with its processing results. The absolute and relative accuracies of mosaicked DSM tiles are validated with ground control points (GCPs) and a variety of height reference data, including DSMs produced by airborne light detection and ranging (LiDAR) instruments. The absolute height accuracy was confirmed at 2.9 m as the root mean square error using more than 3000 GCPs on the mosaicked DSM tiles.
During the 3.5-years of operation of the Greenhouse gases Observing SATellite (GOSAT), the GOSAT Data Handling Facility (DHF) of National Institute for Environmental Studies (NIES) has been producing many of the standard data products from the observation data of the two sensors, the Thermal And Near-infrared Sensor for carbon Observation (TANSO) - Cloud and Aerosol Imager (CAI) and the TANSO - Fourier Transform Spectrometer (TANSO-FTS). The standard data products, CAI Level 1B/1B+, FTS Short Wavelength Infra Red (SWIR) Level 2 (column amounts of CO2 and CH4, including column-averaged dry air mole fraction, XCO2 and XCH4), FTS Thermal Infra Red (TIR) Level 2 (profiles of CO2 and CH4 concentrations), CAI Level 2 (cloud flag), FTS Level 3 (global map of XCO2 and XCH4), and CAI Level 3 (global radiance and global reflectance), have been provided to General Users (GU). In addition, CAI Level 3 Normalized Difference Vegetation Index (NDVI) and Level 4A (CO2 flux) and Level 4B (global 3-dimensional CO2 concentration) have been released to GU since late 2012. Since the FTS SWIR Level 2 data have been accumulated more than three years, seasonal variation and annual trends of XCO2 and XCH4 are shown for more than three years. In 2012, the versions up of FTS Level 1B, CAI Level 1B, CAI Level 2 cloud flag, and FTS SWIR Level 2 were done, and the data quality of the new version has been significantly improved for each of them. By using the new version of the FTS SWIR Level 2 product, the higher level products (Level 4A and Level 4B products) have been produced and released.