Akihide Kamei

Long-term cross-calibration of the Terra ASTER and MODIS over the CEOS calibration sites

The Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) and theModerate Resolution Imaging Spectroradiometer (MODIS) onboard Terra satellite, which have different spatial resolution, can observe the earth surface simultaneously. Both of these sensors have been operated more than 10 years, and it is very useful for cross-calibration because of their simultaneous observations mostly without BRDF effect. On the other hand, the CEOS IVOS group arranges the pseudo-invariant standard test sites for cross-calibration, which are able to evaluate the long-term stability among multiple sensors. This paper shows the TOA reflectance comparison between ASTER and MODIS sensor over the CEOS pseudo-invariant standard test sites.

The long-term vicarious and cross calibration plan for Hyper-spectral Imager Suite (HISUI)

The hyperspectral and multispectral remote sensing mission named HISUI is the Japanese next-generation Earth observation project that will be onboard ALOS-3. HISUI will be composed of hyperspectral imager (185 spectral bands in VNIR-SWIR region with 30 m spatial resolution) and multispectral imager (4 spectral bands in VNIR region with 5 m spatial resolution). To expand use of Earth observation data from HISUI, quality assurance and control of data products is indispensable, therefore, the long-term radiometric calibration has a crucial role. The objective of this research is to establish the techniques and develop the plans for conducting the in-flight radiometric calibration of HISUI with high frequency, reliability, and stability, based on the traditional in-flight radiometric calibration for multispectral sensors.

Aster Digital Elevation Model and orthorectified images generated on the GEO Grid

The ASTER on-demand processing service, which provides a Digital Elevation Model (DEM) and orthorectified images was developed and deployed on the GEO Grid system. It is designed to support the latest algorithms for radiometric and atmospheric corrections developed by researchers as well as the geometric correction and other DEM processing options. The functions and options in this service are developed and implemented as modules, so that they can be arranged as the user requires. Although the system is an experimental, it can provide higher quality data sets than the standard products.

Cloud profiling radar (CPR) for EarthCARE and synergy algorithm studies

Design study and algorithm development efforts are overviewed with cloud profiling radar (CPR) for EarthCARE mission. EarthCARE is a candidate for the ESA Earth Explore Core Missions and presently Phase A study is ongoing. EarthCARE is jointly proposed by European and Japanese scientists, and CPR is being studied by CRL and NASDA, Japan. The EarthCARE CPR is characterized by very high sensitivity 94 GHz radar with nadir pointing and Doppler measurement capability. CPR is designed to maximize synergy performance in combination with other onboard active and passive sensors. In this report, after summarizing CPR objectives and expected performance in responding to requirements, study topics concerning Doppler capability and variable PRF techniques are discussed. The EarthCARE synergy algorithm development efforts through airborne campaign experiment are also introduced.

An assessment of ASTER surface reflectance products generated by GEO Grid

The GEO Grid is an e-infrastructure, which is capable in archiving large amount of satellite data and conducting higher level processing using the advanced grid technologies.1 The Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) Level 0 data are stored in a cluster system on GEO Grid, and ASTER ortho-rectified radiance and Digital Elevation Model (DEM) products are able to be generated on this system globally since 2000. This research shows validation of new ASTER surface reflectance products generated by the GEO Grid system, which can apply the radiometric and atmospheric correction to ASTER ortho-rectified radiance data of Visible and Near Infrared (VNIR) and Shortwave Infrared (SWIR).

Impact of Changes in Minimum Reflectance on Cloud Discrimination

Greenhouse Gases Observing SATellite-2 (GOSAT-2) will be launched in fiscal year 2018. GOSAT-2 will be equipped with two Earth-observing instruments: the Thermal and Near-infrared Sensor for carbon Observation Fourier Transform Spectrometer 2 (TANSO-FTS-2) and TANSO-Cloud and Aerosol Imager 2 (CAI-2). CAI-2 can be used to perform cloud discrimination in each band. The cloud discrimination algorithm uses minimum reflectance (Rmin) for comparisons with observed top-of-atmosphere reflectance. The creation of cloud-free Rmin requires 10 CAI or CAI-2 data. Thus, Rmin is created from CAI L1B data for a 30-day period in GOSAT, with a revisit time of 3 days. It is necessary to change the way in which 10 observations are chosen for GOSAT-2, which has a revisit time of 6 days. Additionally, Rmin processing for GOSAT CAI data was updated to version 02.00 in December 2016. Along with this change, the resolution of Rmin changed from 1/30° to 500 m. We examined the impact of changes in Rmin on cloud discrimination results using GOSAT CAI data. In particular, we performed comparisons of: (1) Rmin calculated using different methods to choose the 10 observations and (2) Rmin calculated using different generation procedures and spatial resolutions. The results were as follows: (1) The impact of using different methods to choose the 10 observations on cloud discrimination results was small, except for a few cases, e.g., snow-covered regions and sun-glint regions; (2) Cloud discrimination results using Rmin in version 02.00 were better than results obtained using Rmin in the previous version, apart from some special situations. The main causes of this were as follows: (1) The change of used band from band 2 to band 1 for Rmin calculation; (2) The change of spatial resolution of Rmin from 1/30° to 500-m.