The geometric characteristics of Moon-based Earth observation platforms differ significantly from those of satellite platforms, with geolocation being a key factor that impacts data quality. The geolocation of a Moon-based sensor is influenced by three key factors: lunar ephemeris (lunar position and libration), Earth orientation parameters (EOPs), and the Earth reference model. Measurement errors from these three sources can significantly affect the geolocation accuracy of a Moon-based sensor. This study proposes a new unbiased estimation method to quantify the geolocation uncertainty introduced by these factors, based on the fusion of multiversion datasets. The method avoids making assumptions about the error distribution of ephemeris parameters while providing an effective approximation of the spatiotemporal patterns of geolocation uncertainty. We integrate three types of ephemeris data, three Earth reference models, and multiple EOPs datasets to assess the overall distribution of geolocation uncertainty and separately evaluate the geolocation uncertainty introduced by each individual factor using control variates method. The results indicate that the maximum total geolocation uncertainty caused by the three factors is about 46 m. Ephemeris errors are the dominant contributor, accounting for more than 98% of the total uncertainty. In addition, measurement errors in lunar libration also account for why longitudinal uncertainty is significantly greater than latitudinal uncertainty.

A Moon-based sensor offers a unique view for continuous Earth observation. The 2-D turntable’s pointing performance is a critical factor influencing geolocation accuracy. The vast distance between the Earth and the Moon amplifies minor pointing errors of the turntable into significant geolocation inaccuracy. By establishing a geometric model, an analytic expression of Earth’s trajectory from the Moon-based view is derived. Three critical issues are discussed: 1) the Earth’s 18.6-year trajectory forms a$16^{\circ } \times 14^{\circ }$envelope, which determines the observation range for the sensor. The rotation angle and position of the envelope vary at different lunar locations, while its size and shape remain consistent; 2) geolocation errors caused by temporal interval vary periodically with a half-sidereal month cycle and can be compensated by calculating Earth’s velocity, while errors due to the step angle show irregular oscillations. Without calibration, both parameters can introduce geolocation errors on the scale of hundreds of kilometers. Reducing both parameters can significantly improve geolocation accuracy; and 3) even with optimization of both parameters, the geolocation accuracy cannot be reduced to within a single pixel. To achieve geolocation accuracy within design requirements, it is necessary to not only optimize these two factors but also adopt additional measures to improve precision. All these insights will inform the parameter optimization and design of the Moon-based sensor for future applications.

Deploying Moon-based sensors at the lunar south polar regions offers unprecedented opportunities for continuous Earth observation. However, previous studies have neglected the combined effects of lunar terrain and latitudinal libration on Earth visibility. This study systematically evaluates the Earth visibility conditions in the lunar south polar regions (80°S–90°S) using high-resolution Lunar Orbiter Laser Altimeter (LOLA) data and a novel visibility algorithm. Results reveal that terrain obstruction reduces Earth visibility by up to 80% in crater-rim and high-latitude regions, rendering the spherical Moon approximation inaccurate for these areas. A 14° maximum elevation angle threshold is identified for complete Earth visibility at lunar south polar regions. Optimal sites cluster near the lunar central meridian (0° longitude) in low latitudes (80°S–82.5°S), balancing extreme observation geometry and terrain occlusion effects. High-visibility areas (≥95%) are fragmented into small patches (82.5°S). This letter has quantitatively characterized the impact of lunar terrain on Moon-based Earth observations, offering guidance for future Moon-based Earth observation sensor deployment and lunar base planning.

The Earth’s outgoing radiation (EOR) at the top of atmosphere (TOA) is an advantageous goal of Moon-based Earth observations. In this study, we focused on the Earth’s reflected radiation (ERR), which is a component of EOR and has a strong relationship with the Earth–Moon–Sun positions. To determine ERR characteristics, we parameterized the Moon-based Earth observation geometry and proposed a method to simulate the ERR at TOA for a Moon-based sensor under clear- and all-sky conditions. The ERR was found to have the distinct cycle of a synodic month and was inversely proportional to the Earth’s phase angle. Clouds increased ERR reflected to space under hemispheric-scale observation; thus, ERR under all-sky conditions was approximately twice as much as that under clear-sky conditions. The ERR was also influenced by incoming solar radiation (ISR), and the removal of the effect of ISR on ERR helped reveal ERR characteristics clearly. The results showed that when the Earth’s phase angle was between 0° and 90°, particularly when the Earth’s phase angle was in the range of 30°–60° and 60°–90° under all- and clear-sky conditions, respectively, the ERR–ISR ratio could indicate the reflective characteristics of the Earth under hemisphere-scale observations. These results will be helpful in demonstrating Moon-based ERR monitoring.

The variation of pointing vector direction for Moon-based Earth observations are analyzed in this paper. The pointing vector direction is parameterized as two angles, namely azimuth and elevation angle. We first establish the observation geometry model to calculate the pointing vector in Moon-centered Moon-fixed (MCMF) coordinate system. Then, the azimuth and elevation angles are defined and their theoretical expressions are deduced respectively. Besides, different observation periods are considered. It is found that the pointing vector direction shows regular variations over one orbital period and 18.6 years. The combination of azimuth and elevation angles can characterize variations of pointing vector direction. They mainly depend on the lunar sub- Earth points. The elevation angle ranges from 83 ° to 97° and the azimuth angle varies from −8° to 8° in an 18.6-year period. These characteristics will give valuable guidance for application of Moon-based platform.

The Moon-based telescope with visible and near-infrared band is equipped on the lunar surface which is 360000 kilometers away from the Earth, and is expected to provide a unique observational data set for the Earth. In this paper, we first proposed an ideal telescope optical system of the Moon-based telescope, then preliminarily designed the stray light suppression structures including the outer baffle and the inner baffle. Further, the geometric model and properties of the telescope structure are established, and the stray light of the Moon-based telescope with visible and near-infrared band is simulated and analyzed by ZEMAX software. The results show that the when the off-axis angle is$4^{\circ}$, the Point Source Transmittance (PST) magnitude is 10−4; when the off-axis angle is more than$20^{\circ}$, the PST is 0. It can be seen that the baffle used in this paper can meet the requirements.

The outgoing longwave radiation (OLR) at the top of the atmosphere is a key component of Earth’s radiation budget. Moon-based OLR observations take Earth as a single point, and provide an alternative to near-Earth orbital measurements. However, in the sensitivity design of a sensor, the effects of adopted Earth’s shape on the design of the sensitivity are particularly severe in the Moon-based OLR observations, which needs to be fully considered. In this study, the observational solid angle related to the ellipsoidal Earth model during OLR measurements was analyzed to improve upon previous studies conducted under the assumption of a spherical Earth. The radiative equilibrium temperature of the Earth–atmosphere system was then applied to simulate the emitted OLR according to Stephen Boltzmann’s law. The magnitude and sensitivity of the Moon-based OLR measurements were estimated by combining the observational solid angle and the simulated OLR. The results showed that the sensitivity of Moon-based OLR measurements is on the order of$10^{-3}$W m−2K−1, and the effects of Earth’s shape on sensitivity estimates cannot be ignored. Further, quantitative estimates revealed that a more realistic (ellipsoid) shape is needed when designing the sensitivity of relevant sensors.

The signal propagation of the lunar-based synthetic aperture radar (LBSAR) is affected by perturbations of the lunar orbit, wherein the apsidal precession that exerts a significant impact on the LBSAR imaging performance of the LBSAR deserves special care. Accordingly, the orbital determination used to maintain well-focused quality and high geometric fidelity in the existing SAR system becomes critical for the LBSAR. In this article, through establishing criteria for the orbital determination of LBSAR based on its imaging performance under the influence of apsidal precession, we investigate the accuracy requirements for the LBSAR orbital determination in terms of the position and velocity determinations. Analysis results show that the required accuracy for the LBSAR position determination depends on the geometric fidelity in the range direction, while the accuracy requirement for the velocity determination is dominated by the azimuth positioning accuracy. The focusing quality is not a primary issue for the LBSAR orbital determination. In addition, the far look angle of LBSAR accounts for the highest accuracy requirement in the position and velocity determinations; thus, it can be treated as the optimum look angle for the LBSAR orbital determination. It is also found that both velocity and position determinations are challenging in the${z}$-direction for the LBSAR.

The imaging performance of the lunar-based SAR (LBSAR) is susceptible to the orbital perturbation effects. In particular, the perturbations of orbital inclination and right ascension of ascending node (RAAN) could give rise to the temporally varying orbit drift of LBSAR and further lead to Doppler errors in the radio signal. As a result, the LBSAR image performance might be influenced by such effects. This study comprehensively probes into the phase error induced by perturbations of orbital inclination and RAAN, and its effects on the LBSAR imaging performance are further explored. It is found the LBSAR imaging performance in terms of focusing quality and geometric fidelity are affected by the perturbations of orbital inclination and RAAN, wherein the deterioration of focusing quality is closely associated with the synthetic aperture time. In this regard, the azimuth resolution on a decameter level is optimum for Earth observation of LBSAR with satisfactory image quality. Regarding the geometric fidelity, the accuracy requirement for the orbit determination of the LBSAR under perturbations of the orbital inclination and RAAN is proposed. The analysis results show that the LBSAR orbit determination in terms of the position and velocity determinations are most strenuous in the z-direction. Finally, point target responses are simulated to illustrate the preceding analysis.

The Moon-based platform has different observation angular characteristics from artificial satellites due to its peculiar orbit. To illustrate the difference, we first normalize the positions and attitudes of the Sun, Earth, and Moon into the same reference system using coordinate transformations. Then, we calculate the observation angles (including viewing elevation angel, solar elevation angel and relative azimuth angle) distribution of satellites in LEO, GEO and at Lagrange L1 satellites during the same period. Furthermore, the observation angles distribution of the Moon-based platform in different seasons with the Earth observed point located at different positions are analyzed. Results revealed that compared to artificial satellites, the Moon-based platform has continuous viewing observation angles and solar observation angles. Its observation angles change with the seasons, and it provides more angular information for equatorial regions than polar regions of the Earth.

Although estimating the Earth radiation budget (ERB) by satellite platforms have become more and more reliable, it is still difficult to carry out conclusive evidence that supports whether the Earth is warming. As the important component of ERB, the measurement requirements of Earth's outgoing radiation are to acquire global-scale absolute calibration data. Observing Earth's outgoing radiation on the lunar surface is a feasible way to improve the consistency and continuity of such data. Since the Moon is a celestial body and the sensor can be equipped anywhere on the near-side of the Moon, the site selection issue of a Moon-based platform will be the most vital step. This paper mainly discusses the site selection issue of a Moon-based Earth radiation budget experiment platform from the perspective of Earth observation geometry. By analyzing observation performance, geolocation accuracy, radiation response and solar invasion effects, we suggest that the mid-high latitude will be a better position to equip sensors.

Moon-based platform is a potential platform that can realize the observations of large-scale geoscience phenomenon. Unlike existing earth observation platforms, the moon-based platform is equipped on a natural celestial body. Its position is calculated by the lunar position and libration derived from the planetary ephemeris. However, limited to the astrometric model and accuracy of observational data, no planetary ephemeris can provide absolutely accurate data, and this will lead to a platform's position error. This letter investigates the impacts of the platform's position error on geolocation for a moon-based sensor. We first made comparisons to the lunar position and libration derived from different planetary ephemerides so as to evaluate the magnitude of the platform's position error. Then, the Monte Carlo method was applied to simulate the platform's position error. According to the geometric model, the effects of the platform's position error on geolocation were presented. The results showed the effects of lunar libration error are associated with position on the lunar surface, while the differences of lunar position error effects are not evidently shown in different positions on the lunar surface. Furthermore, high-latitude regions of the moon are demonstrated to have less impact on the platform's position error, which would be suitable for equipping earth observation sensors.

The spatiotemporal coverage of a Moon-based synthetic aperture radar (SAR) is analyzed based on the imaging geometry, upon which the spatial coverage and image formulation rely. The distance from the Earth to the Moon-based SAR and bounds of the grazing and azimuthal angles jointly determine the coverage area on the Earth's surface. Meanwhile, the ground coverage of the Moon-based SAR is determined by the bounds of the grazing and azimuthal angles and geographic coordinates of the nadir point at a specified time. Moreover, the temporal variation in the spatial coverage is pertinent to the temporally varying nadir point of the Moon-based SAR on the Earth's surface. Furthermore, numerical simulations using the lunar ephemeris data are carried out to complement the analysis and to illustrate the spatiotemporal coverage. Finally, a guideline for the optimal site selection of a Moon-based SAR is proposed. In conclusion, a Moon-based SAR has the potential to perform long-term, continuous Earth observations on a global scale to enhance our capability to understand the planet.

Recently, moon, the unique earth's natural satellite, was proposed as a new platform for large-scale geoscience phenomena observation. However, the geometry between sun, earth and moon, was the precondition to understand the moon-based earth observation from the point of the sun-target-sensor geometry. If a sensor was arranged on moon's surface, the location of the sensor will affect the earth observation geometry directly due to the longer observation distance. After designing and implementing the geometry simulation system, we use it to simulate the geometry for moon-based earth observation (MEO) and discuss the influence of moon-based sensor (MBS)'s location on earth observation. In this work, some of the intelligible aspects are taken into account, including the MBS's subpoint, the earth interests' azimuth-elevation angle for the MBS and the observation duration. We calculated the three aspects under the geometry numerical simulation system and using the JPL DE data, and the results show that the MBS's location affect the three aspects directly but with different degree.

There is increasing concern about the new potential platform for Earth observation - the Moon-based Earth observation platform. The Moon-based platform has the advantages of large-scale, constant and long-term dynamic Earth observations, when compared with the space-borne and airborne platforms. Some scholars have presented ideas for the construction of Moon-based Earth observation, however, most of them ignored the impact caused by lunar terrain. In this paper, we propose a Moon-based Earth observation intervisibility algorithm, based on the Lunar Orbiter Laser Altimeter (LOLA) data. Then we apply the algorithm to the Sinus Iridum area and the Mare Nectaris area and analyze the inter-visibility conditions of the two areas. This intervisibility algorithm will give support to the site selection of future Moon-based Earth observation system or lunar exploration missions.

To deepen the understanding of the Moon-based Earth observations, we establish a new kind of expression of the observation angle. Considering the Earth as a single point, the relative azimuth angle and viewing zenith angle of a Moon-based platform are defined. We first summarize the general procedures of the geometrical model. Based on the geometrical model, the positions of the Sun, the Earth, and the Moon can be acquired. Then, the new expressions of the observation angles are defined in the International Terrestrial Reference System (ITRS). The relative azimuth angle is related to the solar direction, while the viewing zenith angle describes the relationship between the lunar position and the Earth Equator. Results revealed the characteristics of the viewing zenith angle and relative azimuth angle, demonstrating the features of Moon-based Earth observations.

Large-scale geoscience phenomena are increasingly attracting more attention because of their great scientific and social significance. However, many existing earth observation systems lack the ability to conduct long-term continuous observations at a regional-to-global scale because of spatial and temporal coverage limitations and systematic bias. Recently, the Moon, the unique Earth's natural satellite, was proposed as a new platform for earth observation of large-scale geoscience phenomena. However, the geometry relationship between the Sun, Earth and Moon was the precondition to understand the moon-based earth observation. In this work, a simulation system of moon-based earth observation was developed based on the Jet Propulsion Laboratory ephemerides, the reference systems transformation, and which was implemented under the Microsoft. NET framework using C# language. In this system, we will carry out the following studies: (1) The position and attitude change rule of moon-based platform. The position and posture of moon are the main factors that affect the Earth observation, which needs to be studied based on the relative motion law and the moon-based platform simulation system. Then, we will study the regularity of the position and the attitude periodicity of the moon-based platform. (2) The regularity of moon-based platform for Earth observation. Based on the proposed moon-based Earth observation simulation system, the changes of the solar angle, observation angle, observation range, sub-satellite point position, twilight line, oblique distance and observation period of the typical moon-based Earth observation sensor are analyzed.

We simulate to perform Earth radiation budget on the lunar surface. This simulation is to support the study of the Earth radiation budget from a new observation strategy. There are two instruments deployed on the lunar surface for monitoring the Earth outgoing radiation and detecting changes at global scale. As opposed to small instantaneous spatial coverage of the space-borne instruments, the instruments equipped on the lunar surface will have the observational scope of whole Moon-facing hemisphere to allow for a better quantification of the Earth outgoing radiation on the planetary scale. In this paper, we make simulations of equipping multispectral camera and active cavity radiometer on the lunar surface and analyze the characteristics of the Earth outgoing radiation acquired by the Moon-based platform.

More and more attention has been paid to taking the Earth as a whole for researching. Though space-borne and airborne platform have acquired various data from the Earth, the existing Earth observation system lack the ability of long-term continuous observation at a global scale. Three-polar regions include the Arctic, Antarctic and Tibet Plateau, which characterized by its large scale and need long-term observation. This will need large-scale, constant and long-term dynamic Earth observation system. Here we established a new platform, Moon-based Earth observation platform, which focuses on the observation of global scale scientific phenomena, turning out to be an ideal platform to study Three-polar regions environment comparison research. In this paper, we propose the Moon-based observation platform, and discuss the system parameters performance briefly and next focus on the potential applications of Three-polar regions.

Although the precision of the surface parameters calculated from satellite data gets higher and higher, it is still difficult to guarantee the temporal consistency and spatial continuity for large scale geoscience phenomena. Developing new earth observation platforms is a feasible way to improve the consistency and the continuity. As the only natural satellite of the Earth, the Moon has special advantages as a platform for earth observation. This paper mainly discusses the advantages and the potential applications of moon-based earth observation, as well as the train of thoughts of further researches.

Although Synthetic Aperture Radar (SAR) can capture rich land cover information as a most important advanced technique in the field of international earth observation, the application effects still limited significantly. One of the reasons is that the study of SAR imaging processing, SAR image processing and SAR applications are usually conducted respectively, and the study on integrating the three processes is lacked. Focusing on the science problem, taking the typical natural distribution targets (surface deformation, sea ice classification) and man-made targets (building complex and collapsed buildings) as examples, some application studies oriented to SAR environmental parameters inversion are conducted, and the information integrated frames and methods are proposed.

It's a new concept to set up sensors on the Moon to observe the large-scale Earth science phenomena. In order to reveal its potentials and characteristics, this paper focuses on the simulative moon-based Earth observation which makes use of the Jet Propulsion Laboratory (JPL) ephemeris and transformations of relative reference frames. By simulating the observation scenes at different time, we analyze the observation conditions, including observation time series, geometry and effective coverage. The result shows that the moon-based Earth observation has advantages in wide swath, continuous observation and large effective coverage which contributes to the monitoring and understanding of large-scale Earth science phenomena.

Global change refers to changes in earth system function at a global scale including atmospheric and ocean circulation, hydrologic and biogeochemical cycles, and changes in resource, land use and others. Global change is characterized by its large scale and needing long-term observation. Moon is an ideal platform for observing global change. In order to reveal its potentials for observing of global change sensitive regions, this paper focuses on the coverage analysis of moon-based earth observation which makes use of the JPL ephemeris and generates observation Boolean matrixes of global change sensitive regions. The result shows that the moon based earth observation has advantages in wide swath, continuous observation and large effective coverage which contribute to the monitoring and understanding of global change.

Synthetic aperture radar (SAR) interferometric baseline parameters form important input for SAR interferometry. In this paper, a nonlinear error model is established for the SAR interferometric baseline and parameterized as a polynomial based on the natural nonlinearity of the orbit of a satellite. Unlike conventional models, the proposed model takes into account the nonlinear part of the baseline error. A theoretical derivation is performed based on the imaging geometry of interferometric SAR, and the results of the analysis show that the parameters of the nonlinear baseline error model can be obtained from the relationship between the orbit, the nominal baseline, the baseline error, and the residual interferogram phase. A sample data set from the Japanese Earth Resources Satellite-1 (JERS-1) L-band SAR is used to validate the proposed model, and the results indicated that the compensation of the residual interferogram phase of the test data is superior to that provided by conventional models.

The Goldstein filter is one of the most commonly used filters for synthetic aperture radar (SAR) interferograms. The level of noise after filtering is controlled by a filter parameter, “alpha,” the value of which is determined by pixels within the moving window. However, when there exist different features within a single filter window, especially along the border, the value of alpha as estimated from the pixels within the window can be inaccurate and this may result in blurred borders in filtered interferograms. This letter proposes a modified Goldstein filter based on the adaptive-neighborhood technique. The idea of this method is to filter each pixel of the interferogram within an adjusted filter patch. In this adjusted patch, the adaptive-neighborhood pixels retain the original phase values while the “background” pixels are replaced by the mean value of adaptive-neighborhood pixels. Then, the Fourier transform of the complex phase is applied to this adjusted filter patch. The difficulty of estimating the noise level near the borders of different features can be decreased using this new filtering method. The quantitative results from real data show that this newly developed method could reduce the phase noise efficiently while also outperforming the Goldstein, Baran and empirical mode decomposition (EMD) filters by preserving the edges in interferograms.

The Goldstein filter is one of the most commonly used synthetic aperture radar (SAR) interferogram filters. This letter proposes a new method to find filter parameters of the Goldestein filter based on noise level derived by the empirical mode decomposition (EMD) method. The filtering parameter determined by this method has a definite physical meaning. We used bidimensional empirical mode decomposition (BEMD) to extract features of an interferometric phase image into multiple scales of spatial frequencies, called intrinsic mode functions (IMF). We constructed a pseudo-SNR (signal-to-noise ratio) with the given IMF component, then the new parameter was applied to the Goldstein filtering method in place of the original fixed value ascertained artificially. The results from simulation and real data show that the performance of the new algorithm outperforms the original Goldstein filter, and its enhanced version, the Baran filter. The quantitative evaluation also shows that modification based on the EMD proposed in our paper minimizes the loss of phase while still reducing the level of noise in an interferogram.

With several advantages superior to low earth orbit SAR, such as high space resolution together with large range swath and short revisit interval, the moon based SAR (MB-SAR) could be a potential data source for global changes monitoring and environment change research. Due to the high stability and ease of maintenance, the novel system is competent for offering a long and continuous time series of remote sensing imagery. In this paper, we discuss the system performance briefly at the beginning, and next focus on its possible applications.

To reliably monitor the deformation of a single landslide is often a difficulty for DInSAR with mid-resolution SAR data. The high resolution SAR systems bring opportunities for the task. Among the landslides in Three Gorges area, Shuping landslide is typical and some previous works using DInSAR have been done during the last years. In this paper, 9 TerraSAR-X spotlight images are used to map the surface displacement of Shuping landslide. Conventional and coherent pixels based DInSAR are both applied. The deformation field of the landslide is mapped and 2 deformtion cones are identified. Meanwhile, this paper gives out the average deformation velocities of the coherent pixels during the period from January to March 2012. It is confirmed that DInSAR can become a valuable tool in studying and monitoring single landslides with high resolution SAR images. In the future, the DInSAR measurements along the line of sight direction should be converted to real slide direction of the landslide and analyzed joint with multi-source data.

The motion of mountain glaciers on the Tibetan Plateau is one of the key parameters in the research of environmental changes, especially the surface velocity variation over a period of years. Due to the abominable geographical conditions of steep terrain and freezing temperature, it is hard to acquire enough information using traditional ground survey. Optical remote sensing images could be useless during some special period with too much cloud cover. The main objective of this paper is to evaluate the performance of the alternative method-tracking offsets from SAR images, and is trying to add to the lacking information of glacier monitoring in west Kunlun Mountain. Three complete and detailed maps of glacier flow velocity fields during 2007-2010 are obtained by procedures of offset detection using cross correlation in Fourier domain. We found that winter glacier motions on the north slope are averagely 1 cm/day faster than south slope, well corresponding to the local topography. Accuracy of the results could be evaluated based on the offsets extracted from the regions obviously stationary, like the flat ground or the bed rock. The potential deviation is on the order of 0.12-0.25 pixels, which is acceptable in such large scale.

Linfen area is dominated by a series of strike-slip active faults and is presently characterized by low or medium seismicity. The Multi-temporal Interferometry SAR (MT-InSAR) methodology provides high resolution assessment of surface deformations over long periods of observation. Stanford Method for Persistent Scatterers (StaMPS) includes a Permanent Scatterer InSAR (PS-InSAR) method and a Small Baseline (SB) method, which are the two categories of MT-InSAR. Over 100,000 PS velocity along the satellite Line Of Sight (LOS) was calculated using ENVISAT images acquired as well as the time series of LOS displacement based on SB method of StaMPS, which mainly show a successive dynamic pattern, i.e., mountains or sub-uplift zones keep rising, and basins or depressions remain subsiding. Moreover, uplift with large scale emerges in the region where Hancheng Fault runs crossing Luoyun Piedmont Fault, which is perhaps caused by the being obstructed of its right-lateral slip. As a result, crustal stress field is accumulating and seismic hazard becomes increasing.

The velocity of glacier is the most important parameter in the study of glaciers and remote sensing is a powerful tool to calculate their surface velocities. Due to persistent cloud cover in this region, it is impossible to acquire enough optical images to provide measurements. However, measurement of the offsets between two SAR images is an effective way to determine surface velocity. In order to do this, offsets both in slant range and azimuth directions are derived from two SAR images. The movement of the glacier during the SAR data acquisition time is calculated after the global part of offsets has been removed by the polynomial fit method. The offsets used for removing the global part are selected on the basis of the Single-to-Noise ratio (SNR) and correlation in area without glaciers but with large topographic changes. The surface velocity of the whole glacier using SAR data will make a significant contribution to the study of glacier dynamics. The Kekesayi glacier can be divided into four parts, based on the velocity map. The results show that the surface velocity of the Kekesayi glacier is different on the different part of the glacier, and offset measurements are an effective method for the study of glaciers.

Landslide in threegorge area is a severe geohazard threatening many people. Conventional differential SAR interferometry (DInSAR) and Persistent Scatterers for SAR interferometry (PSInSAR) technique are unsuitable for landslide deformation monitoring in this area due to temporal and lack of natural phase stable point targets. The method of DInSAR using corner reflectors (CRInSAR) is a powerful tool in the vegetation area. The procedure of DInSAR using corner reflectors (CRInSAR) used by this paper is briefly introduced. Using ENVISAT ASAR time series data, the deformation of 12 corner reflectors (CR) in Shuping landslide are analyzed. As to the CR with slow creep deformation, the CRInSAR results are reliable. But as to the CR with nonlinear accelerated deformation, our CRInSAR method still needs to be enhanced.

In this paper, the methods, primary PS-like method and Stanford Method for PS (StaMPS) are both studied and used to monitor the subsidence in Tianjin area.