Koto Tinggi is one of the vulnerable soil movement areas in Lima Puluh Kota Regency. The steep slope condition is one of the main causes in this area, coupled with inappropriate land use. The construction of settlements on steep cliff slopes increases the risk of landslides that can cause property and life loss, especially Lima Puluh Kota Regency is a developing district. The availability of complete and accurate information on the vulnerability zones of soil movement is very necessary to prevent and minimize the loss of life and economic impacts. This research was conducted with the aim of the geological factors combined with the Remote Sensing and Geographical Information System used to determine the influence of soil control factors and the development of the vulnerability of soil movement.

This letter proposes a new atmospheric phase screen (APS) compensation method for ground-based synthetic aperture radar interferometry (InSAR). Conventionally, the APS trend is retrieved employing the assumption that the displacement component is a high spatial frequency component, thus making it separable from the APS trend and easy to be identified as outliers during the trend estimation whether using least squares or spectral analysis. However, landslides generally occur over a wide area forming a low spatial frequency component similar to the atmospheric component, which could give significant bias during the parameter estimation. This led to the suppression of the observed displacement from its true since it was partly misidentified as the APS. This specific APS misidentification issue is rarely mentioned in previous literature regarding APS compensation. A robust method to address this issue is proposed in this letter, dubbed best subsample consensus (BeSSaC). This method employs a robust estimation technique using the least median absolute residual criteria, it is shown that a wide-displacement component can be effectively separated from the APS using this technique.

LAPAN-A3, an Indonesian small satellite launched in 2016, carried a magnetometer sensor as one of its payloads to measure the Earth’s magnetic field for a scientific mission. As it is not the satellite’s primary mission, there are some limitations due to the lack of onboard instruments. First, only one fluxgate magnetometer onboard without a scalar magnetometer, which is commonly found in other satellites. Second, the satellite does not have a boom for the magnetometer. With such limitations, the mission becomes a unique problem compared to other satellites. This research studies the residual measurement and the factors that may degrade the measurements. The data that was used is all the 2019–2020 measurements. These resulted in 94.3% of scalar components having residuals less than 300 nT and 91%, 93.1%, and 92.9% of the North, East, and Down components, respectively, with residuals less than 500 nT. It is revealed that three factors affect the measurement, the availability of the satellite’s attitude data, the satellite activity, and system time inaccuracy. While the magnetorquer activity is the most significant, communication to the ground also affects the measurements. It is also revealed that the system time inaccuracy can increase residuals in vector or scalar components more than the unavailability of attitude data.

This paper extends the Convolutional Neural Network to a neural network composed of local filters to diversify its processing unit called Speckle-Network-X (SNet-X), which can better realize the despeckling task on polarimetric SAR images. Neurons in SNet-X are designed based on Linear Minimum Mean Squared Error Filter (LMMSE-Conv) and Diffusion Filter (Diffusion-Conv). The combination of the mathematical modelling filter and the deep learning method enables these traditional local filters to achieve multiple iterations and possess self-adaptive capabilities, which is conducive to mastering the distribution information of noise and the local texture feature simultaneously. This paper also proposes a joint-training method using the loss function to make different filter neurons learn from each other and help the model improve the despeckling efficiency. The superiority of our model has been verified on simulation data, spaceborne linear polarimetric SAR data and airborne circular polarimetric SAR data. It is demonstrated that this method can be applied to any polarimetric channel for despeckling. Moreover, considering the lack of reliable reference images for real SAR data, this paper introduces a segmentation method named TeacherNet (TN) to evaluate the despeckling results, which is closer to subjective evaluation than statistical indexes. All the code and pretrained weights related to this paper will be made public on this website: https://github.com/YuFan-Cai/SNet-X.

Application of fully polarimetric synthetic aperture radar (PolSAR) for detection of archaeological site in Muaro Jambi, Indonesia, is presented. Scale mode of manmade structure is constructed and is measured using setup reproducing ALOS PALSAR2 full polarization strip map mode. The backscattered signal is then decomposed and analyzed for each scattering mechanism. Both scale model and satellite measurement is analyzed. It is shown that the scattering mechanism of scale model confirms theoretical and real measurement of satellite data.

The south coast of Java is located in an active subduction zone where the Indo-Australian plate is beneath the Eurasian plate with a velocity of 7,0 cm/year. The phenomena lead to the area front of disaster, especially earthquakes and tsunami. Some areas along the coast of JAVA are being pressed (subsidence) or lifted due to the tectonic activity of the plate. Also, the activity can result in the creation of areas that have the potential to experience ground movement. However, information about it with scientific evidence is still inadequate. Therefore it is necessary to observe the effects of tectonic activity in southern Java on land surface changes along the coastline and estimate the potential epicenter of earthquakes due to this activity. In this study, we observed land deformation along the southern coast of Java to determine which areas experienced significant deformation. Based on the result, we can estimate the future earthquake's potential epicenter and the land movement area. Also, we analyzed the duration required since the last observation of earthquake events or land movement in the area. The land deformation observation uses satellite radar SAR data of ALOS-2 PALSAR-2 provided by JAXA. The type of SAR data is a stripmap with a 3 x 8-meter resolution. The time acquisition varied for each area observed from 2017 to 2020. The covered area of studies is spread from West to East (Pandagelang, Lebak, Sukabumi, Cianjur, Garut, Pangandaran, Banjar, Cilacap, Kebumen, Purworejo, and Bantul).

Weather observations are usually derived from measurements and monitoring by sensors, radars, satellites, and human observation. Remote cameras are also used; however, meteorological experts typically report changes in the sky, clouds, and weather based on these images every hour or longer. Moreover, it is challenging to install additional cameras in more locations due to the lack of such experts. Because of the complexity of cloud textures, state-of-the-art (SOTA) Deep Learning (DL) models have been applied to limited cloud types, mainly in clear weather conditions. In addition, sky, cloud, and weather recognition from camera images typically implement multiple DL models. However, SOTA DL models have not considered the impact of weather changes, i.e., rain. This paper proposes PanopticBlue, an integrated transformer-based camera-sky-cloud-weather image recognition and classification model under adversarial weather conditions. Scene object recognition is also used to reduce cloud-type classification errors by DL. Experimental results show the superiority of the proposed DeepTex for many cloud types, i.e., unique cloud recognition, twilight cloud recognition, and Cb type cloud, and weather changes, i.e., rain, lightning, and fog, in enhanced accuracy and robustness over SOTA DL models. Moreover, vision language is used to enrich auto-briefing in weather conditions.

Aviation turbulence is a well-known meteorological hazard that can result in aviation mishaps. This study aims to identify the characteristics of aviation turbulence. Hence, we proposed a method to determine the turbulence from the altitude change data obtained from the Automatic Dependent Surveillance-Broadcast (ADS-B) and spatial temperature difference (STD) of Band 13 Himawari-8 in this research. We employed these methods to investigate turbulence in the cruising phase in the flight route from Soekarno Hatta Airport Jakarta (CGK) to Juanda Airport Surabaya (SUB) and vice versa (VV) at Java Island, Indonesia, in July, and December 2019. The result indicates that in July, high-frequency vertical turbulence occurred at 31000 feet. While in December took place at a height of 33000 feet. Horizontally, the turbulence occurs in northern central Java Island. In July, non-convective turbulence was preeminent, whereas convective turbulence was prevalent in December. The dominant STD surrounding the turbulence event is between 0.4° and 0.5°. In the future, this technique will be used to monitor the distribution of turbulence in Indonesia.

In Indonesia, extensive tropical peatland has been facing land degradation due to deforestation and drainage canal construction. Such activities lead to the decrease of groundwater level (GWL), accelerating the peat decomposition, followed by peatland subsidence. This study addresses to estimate a three-year (from Jan. 2018 to Jan. 2020) tropical peatland subsidence over Kalimantan, Indonesia, using the time-series interferometric synthetic aperture radar (TlnSAR) technique by Sentinel-IA. TlnSAR analysis revealed the apparent large displacement found in 2019 due to a significant decline of GWL caused by positive Indian-Ocean dipole mode (IOD) event compared to other years. Furthermore, we employed GWL derived from satellite-based remote sensing data to investigate the relationship between subsidence and GWL and showed a mutual relationship.

In this research, we propose a sub-array antenna that is the core of the X-band antenna for circularly polarized SAR (CP-SAR) onboard an unmanned aerial vehicle (UAV). We aim to realize a high-resolution CP-SAR with a wide bandwidth of 800MHz and a low axis ratio. For this purpose, we designed an ax -shaped radial surface with square slots and prototyped a low-axis band antenna using sequential array technology arranged in 4×4. The basic characteristics of the prototype antenna were verified by experiments in an anechoic chamber.

This research developed a lightweight and robust radome for UAV and airborne circularly polarized synthetic aperture radar (SAR) using novel polymaterial. This paper discussed characteristics of polymaterial for radome designed for airborne SAR, ground test, and flight test at Yogyakarta, Indonesia in August 2017. The polymaterial radome acquired about 1 dB improved scattering gain compared to carbon fiber radome. In the future, the proposed radome using polymaterial is considered could be applied for radome of UAV and airborne, also mobile devices like vehicles, ships, and aircraft, and fixed ground devices of 5G and 6G.

Our laboratory developed airborne circularly polarized synthetic aperture radar (SAR) for disaster and environment observation. This paper explains the investigation of scattering characteristics of circular polarization in the ground test and flight test of circularly polarized SAR in the Hinotori-C2 mission onboard CN235MPA aircraft in March 2018 at Makassar, Indonesia. The ground test was held to investigate a multi-polarized single pulse scattering from various corner reflectors. The flight test was done with multipath to collect the full polarimetric circularly polarized images. The circularly polarized scattering clarification was done using trihedral, cylindrical, and omni corner reflectors. The result shows good agreement with the theory and our previous research. The proposed circularly polarized SAR will be employed in further study of scattering and calibration techniques.

Several techniques have been proposed to observe long-term land surface deformation using phase information of synthetic aperture radar (SAR), for example, interferometric SAR (InSAR), differential interferometric SAR (DInSAR), permanent scatterer interferometric SAR (PS-InSAR), and small baseline subset (SBAS) using images of JERS-1, ALOS-1/2, ENVISAT, ERS-1/2, RADARSAT-1/2, TerraSAR-X, SENTINEL-1A/B, and so on. These methods have also been employed to investigate land deformation and the impact caused by the hot mudflow accident at the study area of regency of Sidoarjo, East Java province, Indonesia, where this disaster happened on May 29, 2006, and has been flowing until now. But these methods only derived the land surface deformation and did not figure geological situation in the Earth, especially the current of geological material outflow. Therefore, this research proposed the continuity equation of the law of conservation of material to estimate the current of material outflow to investigate the impact of the land surface disaster in the study area. The information of vertical deformation or subsidence is derived by the consecutive DInSAR using multispaceborne SAR and substituted into the proposed equation to estimate the volume and current of hot mud outflow. The differential global positioning system (GPS) data collected since 2006 were employed to validate the analysis result of land surface deformation, and the root means square (rms) error is 0.46 m. The result obtained the current at the center of the study area at the beginning of the mudflow period was 6800 m3/day and decreased from 2018 until now that matched well with the local reports. The proposed equation could also be applied for observation of land deformation, volcano, fault activity, underground water, and so on, using remote sensing technologies.

Several techniques have proposed to observe long-term land deformation using phase information of synthetic aperture radar (SAR), for example, InSAR, DInSAR, PS-InSAR, SBAS using spaceborne SAR images. But every mission of spaceborne SAR has an orbit duty period less than ten years and other problems of discontinuity or blank period of observation using the similar specification of sensors. Hence land deformation with an observed time of more than ten years is not available to be monitored continuously using a single mission. This research proposed a method called Bridging Consecutive DInSAR (BC-DInSAR) to connect Consecutive DInSAR. These methods were employed to investigate land deformation and the impact caused by hot mudflow accident at Regency of Sidoarjo, Indonesia, where this disaster happened on 29 May 2006 and is flowing until now. The differential GPS data since 2006 was employed to validate the analysis result of BC-DInSAR, which obtained 0.46 m RMS error.

Chiba University proposed and developed airborne and high altitude platform system (HAPS) onboard C band circularly polarized synthetic aperture radar (CP-SAR) for environment and disaster monitoring on altitude 2–20 km. This paper explains concept, system configuration, RF system and antenna, and flight test of CP-SAR in Hinotori-C2 (Firebird-C2) mission onboard CN235MPA aircraft on 14–15 March 2018 at Indonesia. The result of flight test depicts full polarimetric CP images that shows good performance of CP-SAR. The assessment of CP image analysis, and novel image classification using axial ratio (AR), ellipticity (ε), and polarization ratio (p) are discussed. We plan to hold the flight test of HAPS onboard CP-SAR in 2023.

There is a tradeoff between an azimuth resolution and signal-to-noise ratio (SNR) in synthetic aperture radar (SAR) imaging. One of solutions is using a spotlight mode SAR. In this mode, however, an observation area is limited compared to a stripmap mode SAR. Thus, we propose a new method using a frequency scanning antenna and steering an antenna beam in azimuth direction to solve the tradeoff without limiting an observation area. The unique and essential point of this method is a large beam steering occurs in azimuth direction on every scan in contrast to a beam steering in a spotlight mode SAR that occurs little by little through an observation.The main outcome of this study is a mathematical model of echo signals for the proposed method, and we conclude that from a result of a numerical evaluation, the method solves the tradeoff in some situations but not all, because a non-negligible side effect exists.

Precise evaluation of cloud types is indispensable for the detailed analysis of the Earth's radiation budget. The split window algorithm (SWA) is an algorithm that has been widely employed for cloud type classification from meteorological satellite imagery. In this study, we apply the SWA to analyze the clouds that appear in the Japan area using the imagery of Himawari-8 meteorological satellite. The brightness temperature (BT) information from band 13 (BT13, 10 μm) and band 15 (BT15, 12 μm) are employed with the BT difference (BTD) between these two bands (BTD13-15). For daytime analysis, the albedo of band 1 (0.47 μm) is also used to discriminate the cloudy and cloud-free areas. The validation of the resulting cloud type (SWA13-15), which includes ten classes including cloud-free condition, is carried out using the space-borne lidar data concurrent with the satellite observations. In addition, two different classifiers, namely, the sequential minimal optimization (SMO) and Naïve Bayes (NB) classifiers are tested with the results of SWA. When about 10% of 2 million data points are used for training the classifiers, the test results reveal that the correctly classified points are 97.0% and 89.5% for the first dataset (observed in July 2015) and 97.4%, and 92.1% for the second dataset (July 2016) for SMO and NB, respectively.

In this research, a Flood Warning System is designed based on Water Level Data image obtained by a simple web camera. The system processes the output data from the water level image into tables and then connect to the flood map database to select the corresponding map to be displayed as a flood prediction image with a GIS program. The system processes the data in real time to provide public users with an accurate flood area prediction. By using this system, user can expect the area which will be affected when the water level rises to allow peoples that live near the affected area to evacuate or at least to prepare for the upcoming flood. This kind of early warning system is expected not only will save the lives of people who live near the affected area but also save their valuables from the flood disaster. The flood area is segmented from LiDAR data at 1 m intervals and the water level is recorded at 10 cm intervals. The resulting area obtained from elevation data is considered as the boundary of the maximum extent of the flood. Each corresponding map layer is linked to specific water level recorded by the camera.

Chiba University proposed and developed airborne C band circularly polarized synthetic aperture radar (CP-SAR) for environment and disaster monitoring. This paper explains concept, system configuration, RF system and antenna, and flight test of CP-SAR in Hinotori-C2 (Firebird-C2) mission onboard CN235MPA aircraft on 14-15 March 2018 at Indonesia. The result of flight test depicts full polarimetric CP images that shows good performance of CP-SAR. The assessment of CP image analysis, and novel image classification using axial ratio (AR), ellipticity (ε), and polarization ratio (ρ) are discussed.

This paper presents the development of circularly polarized microstrip antenna using triangular truncation with axial ratio enhancement for X-band communication of Synthetic Aperture Radar (SAR) system. It is well-known that the axial ratio is ome of most essential characteristics in term of antenna with circular polarization. Many methods had been reported in attempting to generate circular polarization, one of them is by utilizing a truncation technique. Thus, in this work a novel truncation shape using a triangular truncation is introduced. The required antenna dimension is less than 40mm×40mm. A single patch antenna is developed by two layers of NPC-H220A substrate with each thickness of 1.6mm and dielectric constant of 2.17. The feeding line is positioned at the middle part between the first layer and the second layer. Here, the proposed antenna attains a decent circular polarization. The axial ratio obtained is 0.49GHz with the low frequency stands at 7.9GHz and the high frequency stands at 8.44GHz. Meanwhile, the minimum requirements of antenna design are 0.4GHz bandwidth with the resonant frequency at 8.2GHz.

In this paper, we attempt to develop the soil moisture retrieval method taking into account a wide variety of vegetation variations for the sparsely vegetated area. The method is constructed by introducing generalized volume scattering model into the polarimetric two-scale two-component model (PTSTCM). The proposed method was applied to L-band fully polarimetric ALOS-2 SAR datasets obtained over tropical peatland, Indonesia. The retrieved results were validated by simultaneously measured in-situ soil moisture. The proposed method yields more improved results than original PTSTCM with specific types of volume model (i.e., randomly, horizontally, and vertically oriented volume models) regarding the root-mean-square-error (RMSE) as well as inversion rate.

Center for Environmental Remote Sensing, Chiba University develops multiband (L, C, and X bands) circularly polarized synthetic aperture radar (CP-SAR) for microsatellite SAR constellation (150 kg class). This paper explains the project, specification, antenna deployment, RF system, and ground-flight test of SAR system at Indonesia. In the future, this microsatellite SAR constellation will be employed to monitor global land deformation and environment.

We developed a novel concept for X-band (center frequency 9.4 GHz, HH polarization) airborne SAR, the Wide Area Long Range Synthetic Aperture Radar (WALR-SAR) onboard a Boeing 737-200 aircraft for simultaneous air and terrestrial disaster monitoring. This paper explains the configuration of our WALR-SAR system and slotted array antenna installed on the Boeing 737-200. Ground measurements of the slotted array antenna were realized to measure the characteristics of antenna and its results are discussed in this paper. Flight test of WALR-SAR onboard Boeing 737-200 in Hinotori-X1 (Firebird-X1) mission was performed during the period of 2 to 10 August 2017 at Pare-Pare and Makassar, Indonesia. Results show good performance of the WALR-SAR system and its image acquisition that covers the depression angle 0.5 to 42.0 degrees.

The Study of the X-band circularly polarized antenna with circle-shaped microstrip patch and triangular truncation factor is discussed in this manuscript. The total dimension of the single patch is less than 40mm × 40mm and the maximum thickness of the proposed antenna is 10mm. This single patch antenna developed in the double layer of substrates NPC-H220A with thickness 1.6mm and the dielectric constant 2.17. The feeding line developed in the middle part between first layer and second layer, the feed-line will be the focus of discussion of this manuscript. In this Proposed antenna, the feeding line designed with bended method, this style produced excellent circular polarization characteristics. The Axial ratio obtained of 0.49GHz with low frequency stand at 7.96GHz while the hing frequency stand at 8.45GHz. The minimum requirement of the antenna design are 0.4GHz of the bandwidth, then the resonant frequency at 8.2GHz.

Circularly polarized (CP) synthetic aperture radar (SAR) is a recent state of art SAR that adopts CP-antennas on both a transmitter and a receiver (end-to-end circular polarization). For use of this SAR configuration practically and precisely, in this paper, we propose two types of point target-based polarimetric calibration methods modified by existing calibration for the linearly polarized (LP) radar. Two proposed methods are applied to a ground-based (GB) CP-SAR system to assess the calibration capability on a polarimetric application. The proposed methods yield more accurate entropy-alpha (H-α) distributions than uncalibrated data. The proposed point target-based polarimetric calibration methods can be applied to the wide-frequency bandwidth CP GB-SAR application.

Center for Environmental Remote Sensing, Chiba University develops L Band circularly polarized synthetic aperture radar (SAR) sensor for microsatellite (150 kg class). This paper explains the project, specification, antenna deployment, RF system, and experiment of circularly polarized SAR in anechoic chamber. In the future, this sensor will be employed to monitor global land deformation.

This paper proposes the phase error compensation algorithm of the wide band chirp generator for the synthetic aperture radar (SAR) use. The proposed algorithm dynamically calculates the phase error of transmitting chirp to reduce spurious of signal. In addition, it uses the curve fitting method and feedback when the desired signal are set by user. Numerical results show that the proposed algorithm can enhance the impulse response function (IRF) results such as the peak to side-lobe ratio (PSLR) and the integrated side-lobe ratio (ISLR) up to −0.1561 dB and −0.0548 dB respectively. Furthermore, the spurious has been reduced by compared to the conventional direct digital frequency synthesizer (DDFS) chirp generators.

This paper introduces the progress of circularly polarized synthetic aperture radar (CP-SAR) development for Boeing 737–200 Aircraft (L, C and X bands) and microsatellite (L band). This sensor will be employed to monitor global land deformation.

The Jakarta province proposed the Jakarta Giant Sea Wall as the waterfront city for the new urban settlement zone and the deep seaport for the new economic zone along the coastal areas at northern Jakarta. This letter investigated land deformation at 11 watersheds of the West Java Mega Urban Region using the persistent scatterer interferometry technique of the Advanced Land Observing Satellite phased-array-type L-band synthetic aperture radar data. The result shows that land deformation at the study area, particularly the Bandung city area gives a significant impact to sedimentation velocity along the eastern Jakarta strait, particularly the deep seaport for 43 years later. This letter recommends to evaluate land conservation at upland watersheds and the well management of artificial canals to reduce the impact of sedimentation at the Jakarta strait, particularly the new depth seaport.

Chiba University develops two microsatellites called GAIA-I and GAIA-II. GAIA-I payload is GNSS Radio Occultation (RO) sensor and Electron Density — Temperature Probe (EDTP) for Ionosphere monitoring, and GAIA-II payload is Circularly Polarized Synthetic Aperture Radar (CP-SAR) for global land deformation monitoring. In the near future, we will employ these microsatellites to investigate relationship of total electron content (TEC), electron density and temperature, and global land deformation to observe precursor of earthquake. This paper focuses to discuss the development progress of GAIA-I microsatellite.

As an imaging radar, synthetic aperture radar (SAR) requires the images of high-resolution. To enhance the resolution of images, SAR adopts the chirp signal [1]. The chirp signal is often referred as a linear frequency modulated (LFM) signal because the instantaneous frequency of chirp signal increases or decreases linearly with the time. To realize the chirp signal in SAR system, the chirp signal generator adopts the direct digital synthesizer (DDS) type arbitrary waveform generator. However, the phase error due to the truncation in DDS degrades spectrum purity of output signal. This paper proposes the phase error compensation method for DDS chirp signal generator using polynomial model. To verify the performance of proposed method, the peak to side-lobe ratio (PSLR) and integrated side-lobe ratio (ISLR) are analyzed. In this paper, compared to the conventional DDS system, the PSLR is improved from −13.5536 dB to −13.6207 dB and ISLR is improved from −10.3263 dB to −10.3126 dB when the proposed method is applied.

Dielectric permittivity εrmeasured on the Earth's surface is an effective property for characterizing surface materials in terms of rock type and water content, particularly in highly changeable environments such as active volcanoes. We propose a technique termed dielectric permittivity from polarimetric synthetic aperture radar (dPSAR) to quantify εrusing a single scene of polarimetric SAR data, based on the small perturbation model of backscattering (SPMB). For an optimal solution, the Nelder-Mead simplex method was combined with SPMB. The application of dPSAR to a scene of ALOS PALSAR data from the vicinity of Mt. Merapi, Indonesia, correctly identified the relative value ranges of εrfor pyroclastic flow and tephra deposits accompanying large eruptions that occurred on November 5, 2010; their means were 2.55 and 3.07, respectively. Pore water within porous ashes is a plausible factor for increases in the εrof the tephra.

This paper introduces the progress of circularly polarized synthetic aperture radar (CP-SAR) development in Center for Environmental Remote Sensing, Chiba University, Japan for unmanned aerial vehicle (UAV, JX series) and microsatellites (GAIA series). This sensor will be used to monitor global land deformation and disaster area.

We are developing L-band Circularly Polarized Synthetic Aperture Radar(CP-SAR) for Unmanned Aerial Vehicle (UAV) and microsatellite. Our SAR base-band processor consists of FPGA and PC block. Base-band processor is basically common part which is adaptable to any type of SAR. Hence the pulse specification must be configured to match any platform and observation situation, and in addition, autonomous pulse variability is required to get more precise SAR image. We developed base-band Tx, Rx part and some post processor by using FPGA and PC. In the future, all functions will migrate from PC to FPGA, and complete low cost SAR system consist of only FPGA and Telecommunication devices.

Synthetic Aperture Radar (SAR) is well-known as a multi-purpose sensor in all-weather and day-night time. In this research, we are developing Circularly Polarized Synthetic Aperture Radar (CP-SAR) onboard microsatellite to observe land deformation on Earth surface under Japanese Ministry of Education and Technology (MEXT) program etc. The CP-SAR employs elliptical wave propagation and scattering phenomenon by radiating and receiving the elliptically polarized wave, including the specific polarization as circular and linear polarizations. The sensor is designed as a low cost, light, low profile of configuration to transmit and receive left-handed circular polarization (LHCP) and right-handed circular polarization (RHCP). Then these circularly polarized waves are employed to investigate relationship of physical information of scatterer and axial ratio, ellipticity, tilt angle etc. This sensor is also considered to reduce the effect of ionosphere's Faraday rotation. For ground experiment of CP-SAR, we also develop the CP-SAR onboard unmanned aerial vehicle (UAV CP-SAR) that is discussed in this paper.

Synthetic Aperture Radar (SAR) is well-known as a multi-purpose sensor that can be operated in all-weather and day-night time. The past SAR sensors for Earth observation mission are commonly operated in linear polarization that sensitive to Faraday rotation effect, especially in low frequency. This paper introduce our Circularly Polarized Synthetic Aperture Radar onboard Unmanned Aerial Vehicle (CP-SAR UAV) that is developed to retrieve the physical information of Earth surface for Earth diagnosis mission. The CP-SAR system is considered as small, light in weight and low power consumption system. The CP-SAR sensor is employing elliptical wave propagation and scattering phenomenon by radiating and receiving the elliptically polarized wave, including the special polarization as circular and linear polarizations. This paper introduces the CP-SAR and UAV system, including simulated full polarimetric CP-SAR images.

In the present paper, we propose the application of a differential synthetic aperture radar interferometry (DInSAR) technique to retrieve the volume changes of the damaged area and the volcanic sediment on the sloped surface of Merapi volcano, Indonesia, which erupted on October 26 and November 4, 2010. This technique was used to investigate the thickness of volcanic ash and the volume change of post-ejected wet lava (sand and rock) surrounding Merapi volcano by assessing L-band ALOS PALSAR data. The results reveal the volume of the damaged area, or deformation, and the volume of sedimentation in the study area are 1.4 million and 2.2 million m3, respectively, and indicate that the radius of the dangerous area is 15.6 km.

A new geospatial data sharing/overlay system, CEReS Gaia, has developed. The purpose of the system development is to promote land surface environmental studies. Since existing databases do not meet the requirements by academic users who wish easy data analysis by using his/her own data with existing other data, the new geospatial data sharing system has developed. The system has the following features; a) internationally unlimited expansion of servers, b) multi-language capability (currently, only English), c) free access without user registration, d) data upload/download by registered users, e) capability to overlay user's data on other registered data, f) option of unlimited or selective data distribution. The system operation has started in August 2012.

In this paper, the long-term consecutive differential interferometric synthetic aperture radar (SAR) technique is used to measure the volume change during land deformation. This technique was used to investigate the subsidence of Bandung city, Indonesia, by assessing the data from two Japanese L-band spaceborne SARs (Japanese Earth Resources Satellite 1 SAR and Advanced Land Observation Satellite Phased Array type L-band Synthetic Aperture Radar) during the periods of 1993–1997 and 2007–2010. The results are confirmed using GPS observation data, ground survey data, local statistics, ground water level trend data, and the geological formation of the study area. The obtained results reveal a close correlation between the subsidence measurements and changes in the ground water level due to water pumping, population growth, industry growth, and urbanization of the study area.

The advancement of remote sensing technology has contributed to a significant level of assistance in reducing nature's calamities, threatening both human lives and property in its immediate vicinity. Volcanic eruption is one of a kind where the dangerous environment surrounding it also causes great difficulties for close-up monitoring and surveillance. Differential Synthetic Aperture Radar Interferometry (DInSAR) is a technique useful for accurately detecting the ground displacement or land deformation in the antenna line-of-sight (slant-range) direction using synthetic aperture radar (SAR) data taken at two separate acquisitions. As one of important targets of the DInSAR analysis, we have studied the volcanic eruption of Miyakejima island, successfully demonstrating the detection of land deformation around its crater.

This study shows that DInSAR methods able to detect the ground deformation which occurred because of underground material eruption, not only in nearby the center of eruption but also in the area far from the center of eruption (more than 4 kilometers apart). The DInSAR analysis can be considered as potential tool to monitor the mud volcano eruption disaster with low cost, especially to detect ground deformation as an impact of such phenomenon which may occurred in remote area or dangerous area in such wide spreading area. The observation continuation becomes important to monitor the ground deformation and to prevent further human severe. In the future, multiple aperture technique and GPS measurement will be applied to get a better result and analysis.

In this paper, we proposed the circularly polarized Synthetic aperture radar onboard microsatellite (μSAT CP-SAR). The CP-SAR is designed as the small, light in weight and low power consumption system. The CP-SAR sensor is developed to radiate and receives circularly polarized wave. This CP-SAR sensor will be applicable for land cover, disaster monitoring, snow cover, and oceanography mapping, etc. We also proposed the CP-SAR UAV for ground experiment at Shikabe airport (Japan) and Sulaiman airport (Indonesia) in 2011–1012.

Various methods proposed for image fusion satellite images are examined from the viewpoint of accuracies with which the color information and spatial context of the original image are reproduced in the fused product image. Image fusion is a useful tool in integrating a high resolution panchromatic image (PI) with a low resolution multispectral image (Mis) to produce a high resolution multispectral image and better understanding of the observed earth surface. In this study, five typical fusion methods of Gram-Schmidt (GS), Ehler, modified intensity-hue-saturation, high pass filter, and wavelet-principal component analysis (PCA) are compared. The spectral quality assessment of the products using these different methods is implemented by image quality metrics. The accuracy of classification result is assessed by means of the support vector machine based on radial basis function kernel. Our analysis indicates that as a whole, the Ehler and wavelet-PCA methods show good performances, followed by GS. Also, the examination of confusion matrix shows that both Ehler and wavelet-PCA yield better accuracies in the classification results.

In this paper, we develop a novel method for forest biomass estimation. The intensity values of Advanced Land Observation Satellite-Advanced Visible and Near Infrared Radiometer type 2 and PRISM images and the texture features of the Japanese Earth Resources Satellite 1 image are used in a multilayer perceptron neural network (MLPNN) that relates them to the forest variable measurements on the ground. A proposed speckle noise model is also applied for modeling and reducing the speckle noise in the synthetic aperture radar (SAR) image. Reducing the speckle would improve the discrimination among different land use types and would make the textual classifiers more efficient in SAR images. Ideally, filters will reduce the speckle without loss of information. In the process of the forest biomass estimation, the filters should preserve the backscattering coefficient values and edges between different areas. We investigate both quantitative and qualitative criteria in speckle reduction and texture preservation to evaluate the performance of the proposed filter in the forest biomass estimation. We will also show that the biomass estimation accuracy is significantly improved in an MLPNN when the radar and the optical data are used in combination compared to estimating the biomass by using a single datum only. The root-mean-square error (rmse) value is decreased when the proposed method is used (rmse= 2.175 ton) compared with that of the classic method (rmse= 5.34 ton).