1. Introduction of Chiba University

Chiba University was founded in 1949 and one of the leading academic research centers of Japan. Currently, Chiba University consists of nine faculties, the university library, the university hospital and nineteen research centers including Center for Environmental Remote Sensing (CEReS) [1]. With approximately 11,000 students in the undergraduate program, it has long been one of the largest national universities in Japan. As for the graduate school, annually there are about 2,500 students in master programs and 1,200 students in doctoral programs. The University's four campuses, Nishi-Chiba, Inohana, Matsudo and Kashiwa-no-ha are ideally located in Chiba Prefecture, an area noted for its industrial, intellectual and international achievements. In recent decades, Chiba has undergone rapid development which in many ways rivals the neighboring Tokyo Metropolis. Many national projects have been based in Chiba Prefecture, and now Chiba has one of the main international transport centers (New Tokyo International Airport Narita), one of the largest business centers and resorts (Tokyo Disney land and Tokyo Disney Sea) in Japan. Many new academic and industrial complexes for the advanced sciences (i.e. The Kazusa DNA Research Institute, National Institute of Radiological Sciences) are located in Chiba Prefecture. The developments in Chiba today are representative of tomorrow's Japan.

Chiba University, with the support of the Japanese national government, is extending the frontiers of its international activities. The University is establishing new cooperative relations with numerous overseas universities and developing an even closer relationship with those with which it has already concluded cooperation agreements. The University has already achieved a high degree of participation in international cooperative research projects. Chiba University presently has a large body of international research scholars and students studying on its various campuses. As of 2010, there are 205 sister universities in 39 countries, 293 international research projects in 41 countries and 1068 international students in 51 countries all over the world. Also, Chiba University has 6 International offices in Canada, Finland, Indonesia, Thailand, and China (Beijing and Hangzhou).

2. Center for Environmental Remote Sensing (CEReS)

The Center for Environmental Remote Sensing (CEReS) has contributed to the science community of environmental studies through archiving, processing and disseminating satellite data since its establishment as a national cooperative research center of academic community on remote sensing in April 1995 [2]-[3]. The mission of the CEReS is to conduct research on remote sensing for understanding environmental changes and the interactions between human and the environment. This mission places the CEReS as Japan's leading institution of remote sensing for environmental applications. The CEReS plays an important mission in research and education for remote sensing field in Japan. In education mission, the CEReS already has graduated 159 master students and 98 doctoral students from domestic and overseas since 1995.

The CEReS started the following three programs as a newly, officially accredited center for cooperative use and research cooperation under the Japan government from April 2010: (1) Program 1 Innovation in remote sensing technology and algorithm, (2) Program 2 Integrated use of geoinformation, (3) Program 3 Advanced application of satellite remote sensing.



Fig. 1. Satellite receiver facilities (NOAA and other satellites) on top of CEReS Building

Program 1 Innovation in remote sensing technology and algorithm (Leader: Prof. Josaphat Tetuko Sri Sumantyo):
The limitation of existing approaches has often been recognized in the course of the Earth environment studies using remote sensing. In this program, novel sensors and algorithms are explored in order to establish new remote sensing methodologies that enable more in-depth and comprehensive analyzes of various target including vegetation and atmosphere. In this way this program aims at the innovation of remote sensing through such activities as construction and operation of next-generation satellite sensors, and the integration of wide spectral-range observations using optical and microwave remote sensors. The goals of Program 1 is the integration of wide spectral-range observations using optical and microwave remote sensing sensors, and practical applications of innovative remote sensing to global and regional problems. The projects under Program 1 are (1) development of polarimetric synthetic aperture radar onboard ummaned aerial vehicle and microsatellite for microwave remote sensing and their application for Earth observation, (2) Feasibility study of air pollutant and other atmospheric minor gas retrieval from geostationary satellites, (3) Information retrieval from next generation sensors for global environment, especially aimed at the atmospheric and vegetation monitoring, and (4) Implementation of validation and various data applications of the next-generation Earth observing satellite GCOM-C.

Program 2 Integrated use of geoinformation (Leader : Prof. Atsushi Higuchi):
This program aims to promote atmospheric terrestrial environmental studies based on integrated use of geoinformation including satellite remote sensing data, ground measurement data, and extracted environmental data. Main research subjects in this program are correction and preprocessing of satellite data, efficient processing methods for a huge volume of satellite data, environmental monitoring method by integrating satellite data and ground data, and extraction of atmospheric / terrestrial environmental parameters. This program has close relationship with the operation of the data distribution and sharing systems of the whole CEReS. The goal of this program is long-term climatology analysis and its implementation by means of the seamless monitoring over more than 20 years, leading to the synergy of land and atmospheric studies and realization of the information center for the Earth environment. The projects under Program 2 are (1) Long-term seamless monitoring of the atmosphere is employed for climatology study, through the high-level analysis of various earth-observing satellites, especially geo-synchronous meteorological satellites, (2) invigorating the atmospheric and land-surface studies through the feedback of the knowledge from the seamless monitoring to the data pre-processing such as calibration and atmospheric correction prior to the land-coverage analysis, (3) the formation of the information center for the earth environment by disseminating the data obtained from this program and other CEReS programs. The international geospatial data sharing system called CEReS Gaia, will promote terrestrial environmental research by integrating existing data and research products through mutual comparison activities.

Program 3 Advanced application of satellite remote sensing (Leader : Prof. Akihiko Kondoh):
Since the establishment of the Aerospace Basic Act in 2008, the major purpose of the national policy over the space development and utilization has changed from the stage of research and development to that of wide-range, practical utilization. Thus, it is absolutely needed for the environmental remote sensing community to establish the methodology of utilization of remote sensing for finding, understanding, and solving various problems on both scientific and social bases. In view of such background, this program aims at assigning important problems that must be solved on national and global levels, integrating the results of satellite and ground-based observations, and realizing the advanced application methodology of satellite remote-sensing data through the synergetic activities of scientists representing various fields of environmental monitoring. As the goal of this program, we plan to produce novel application methodology of satellite remote sensing data in combination with the data obtained from ground observations. The targets will include various problems such as desertification, water problem, food security, evaluation of ecological services, urban and rural planning etc. The projects under this program are (1) Monitoring and causal analyzes of environmental changes in Asia, (2) Restorations of sound hydrologic cycle and biodiversity in Chiba prefecture, (3) Study on spatial information system that nurtures the disaster and environmental literacy, and (4) Construction and provision of spatial information helpful to our daily life.

3. Josaphat Microwave Remote Sensing Laboratory (JMRSL)

Josaphat Microwave Remote Sensing Laboratory (JMRSL) in Program 1 of the CEReS promotes research and education in microwave remote sensing technology and science for future Earth observation, especially development of next generation of synthetic aperture radar (SAR), SAR image signal processing techniques for unmanned aerial vehicle (UAV), aircraft and microsatellite, and SAR image applications [4]. The main projects in JMRSL are (1) Development of circularly polarized synthetic aperture radar (CP-SAR) onboard UAV and microsatellite, (2) Compact CP-SAR for UAV, (3) SAR image signal processing, (4) theory and measurement technique of SAR system, (5) microwave circuits and antennas development for SAR, rocket tracking, GPS-SAR, GPS - radio occultation (RO) sensors, (6) 3 dimensional weather radar and vehicle onboard radar for ice and snow monitoring (see Fig. 2), and (7) long-term consecutive environmental change monitoring by using old maps and satellite images. JMRSL has collaboration with researchers from University of Tokyo, Nihon University, Kyoto University, Osaka University, Japan Aerospace Exploration Agency (JAXA) and some high research dedicated companies Weathernews, PASCO etc to develop some new technology in remote sensing field. Our laboratory has many study sites in the world for field survey to promote global research and education in microwave remote sensing field. JMRSL already has developed the CP-SAR UAV (see Fig. 3) and microsatellite during the fiscal year 2007 to 2009 under the supporting of Japanese Ministry of Education and Technology (Monbukagakusho), Chiba University Center of Excellent Start-up Program - Microsatellite Institute for Earth Diagnosis, the Japan Society for the Promotion of Science (JSPS); National Institute of Information and Communication Technology (NICT) etc.



Fig.2. Prof. Josaphat (yellow jacket) with students held ground survey to investigate the circular polarization of microwave characteristics of snow and ice at Saroma Lake, Hokkaido, Japan by using synthetic aperture radar (SAR) and microwave radiometer 18 GHz and 36 GHz.



Fig.3. CP-SAR, GPS-SAR and GPS-RO sensors onboard Josaphat Laboratory Experimental Unmanned Aerial Vehicle (JX-1)

3.1. Circularly Polarized Synthetic Aperture Radar

Synthetic Aperture Radar (SAR) is well-known as a multi-purpose sensor that can be operated in all-weather and day-night time. Recently, many missions of SAR sensors are operated in linear polarization (HH, VV and its combination) with high power, sensitive to Faraday rotation effect etc. In this research, we proposed the Circularly Polarized Synthetic Aperture Radar onboard microsatellite (CP-SARSAT) that will be launched five years later to retrieve the physical information of Earth surface for Earth diagnosis by using the characteristics of circular and elliptical polarizations. Before the development of microsatellite, we developed UAV for ground experiment of our microwave sensors, including the CP-SAR sensor. Fig. 4 shows the concept of CP-SAR UAV. The CP-SAR sensor is employing the elliptical wave propagation and scattering phenomenon by radiating and receiving the elliptically polarized wave using circular polarized antennas (right- and left-handed circular polarization : RHCP and LHCP), where elliptical polarization includes the special polarization as circular and linear polarizations. UAV is employed for ground experiment (validation and calibration) of CP-SAR before we install this sensor in the microsatellite. The sensor is designed as a low cost, light, low power or safe energy, low profile configuration to transmit and receive LHCP and RHCP, where the transmission and reception are both working in RHCP+LHCP as shown in Fig. 4. Then the circularly polarized waves are employed to generate the axial ratio image (ARI), tilted angle spectrum image, ellipticity ratio image, etc. This sensor is considered not depending to the platform posture, and it is available to avoid the effect of Faraday rotation during the propagation in ionosphere when installed in microsatellite. Therefore, the high precision and low noise image is expected to obtain by the CP-SAR.

3.2. CP-SAR Onboard Unmanned Aerial Vehicle (CP-SAR UAV)

In this research, the CP-SAR onboard unmanned aerial vehicle (CP-SAR UAV) as shown in Fig. 3 is developed for CP-SAR ground testing before install it on the microsatellite. The platform called Josaphat Laboratory Experimental Unmanned Aerial Vehicle (JX-1) has 25 kg of payload availability for various microwave sensors (CP-SAR, GPS SAR, and GPS RO) and optic sensors (visible cameras). The UAV operation altitude is 1,000 m to 4,000 m as the optimum altitude for L band CP-SAR sensor.

The specification of CP-SAR sensor for UAV: frequency 1.27 GHz, ground resolution 1m, pulse length 3.9 to 23.87 ms, pulse bandwidth 61.14 to 244.69 MHz, off nadir angle 40^o to 60^o, swath width 1 km, antenna size 1.5 m x 0.4 m for LHCP and RHCP, azimuth beamwidth 6.77^o, range beamwidth 29.78^o, antenna radiation efficiency >80%, PRF 1000 Hz, and peak power 8.65 W (1 km) to 94.38 W (4 km). The CP-SAR has receiver antenna composed by LHCP and RHCP antenna. The data retrieved by LHCP and RHCP antenna is employed to generate the axial ratio, tilted angle, ellipticity ratio etc of images. This image is used to retrieve the physical information of Earth surface, i.e. soil moisture, biomass, Cryosphere, agriculture, ocean dynamics, land deformation, disaster monitoring, digital elevation model etc. In this UAV, we also install the linearly or horizontally polarized SAR (LP-SAR) in frequency P-, L-, and X-bands as shown in Fig. 4. The Linearly polarized SAR data will be compared with CP-SAR data, and employ it for some applications.

3.3. CP-SAR MICROSATELLITE MISSION

We employ three microwave sensors in CP-SAR μSAT mission as main sensors, there are CP-SAR, GPS-SAR and GPS-radio occultation (RO), as shown in Figs. 5 and 6. GPS-SAR is an experimental passive SAR sensor. This mission plans to investigate the possibility to receive the GPS pulse and process it to retrieve the SAR image. GPS-RO is an experimental four unit of patch array antenna sensor to receive the GPS signal and process it to retrieve the conditions of electron in the ionosphere to investigate the coupling of total electron charge or density change (GPS-TEC) and land deformation on Earth surface. This coupling is used to predict the earthquake activity with magnitude more than 5, and build the early warning system in Asian countries in the near future. CP-SAR is as active sensor that could transmit and receive the L band chirp pulses for land deformation monitoring, especially for post disaster monitoring.