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The monitoring of urban land surface subsidence is the main task of urban disaster prevention and mitigation. In this paper, the land surface subsidence process in Changchun metropolitan area is calculated based on PS-InSAR technology by using the SLC data of Sentinel-1B with 50 scenes within the metropolitan area of Changchun from 2016 to 2020. The results show that the metropolitan surface of Changchun is basically in a stable state, the main settlement is located in the southeast of the metropolitan around the Century Square, the maximum settlement rate is 20.45mm/a, the average settlement rate is 2.98mm/a, the correlation coefficient between the settlement results calculated by PS-InSAR and the second-class leveling verification results reaches 0.67, which indicates that the regional settlement results calculated by PS-InSAR have high reliability. The subsidence area is dominated by the geological structure of the Mesozoic Cretaceous Yaojia Formation, with many intercalations of fine silty sand rocks and locally containing medium-coarse gravel sandstone. The overall structural stability is poor, which may be the main reason for subsidence in this area.
He Wang; Jiuchang Mao; Shijun Zhao; Xinguo Ning; Qiong Wu. PS-InSAR based surface subsidence analysis in Changchun metropolitan area. E3S Web of Conferences 2021, 290, 02006 .
AMA StyleHe Wang, Jiuchang Mao, Shijun Zhao, Xinguo Ning, Qiong Wu. PS-InSAR based surface subsidence analysis in Changchun metropolitan area. E3S Web of Conferences. 2021; 290 ():02006.
Chicago/Turabian StyleHe Wang; Jiuchang Mao; Shijun Zhao; Xinguo Ning; Qiong Wu. 2021. "PS-InSAR based surface subsidence analysis in Changchun metropolitan area." E3S Web of Conferences 290, no. : 02006.
Single-frequency precise point positioning (PPP) is widely used with the advantage of cost-efficient, while its further development and application are limited by the difficulty of ionospheric delay correction and the long-time convergence, especially for real-time positioning. And the development of high-accuracy ionospheric models plays an important role for the correction of ionospheric delay in single-frequency PPP. In this paper, the final and rapid global ionospheric map (GIM) products released by Chinese Academy of Science (CAS), Center for Orbit Determination in Europe (CODE), European Space Agency (ESA), Jet Propulsion Laboratory (JPL), Universitat Politècnica de Catalunya (UPC), Wuhan University (WHU) and International GNSS Service (IGS) were used as external constraints in static, simulation kinematic and kinematic single-frequency PPP respectively. The performance and practicality of each product were analyzed by using IGS station observation data (September 2017 and January 2018, with different ionospheric activity levels) and a kinematic experiment. The results indicate that GIM products may improve convergence time in most areas of middle and high latitudes of the globe. However, the improvement of convergence time of some regions in low latitudes or near the equator with dense and uniform distributed IGS stations show even better performance than the regions in middle and high latitudes. Comparing with standard PPP (S-PPP), the convergence time of static PPP is reduced about 14–42% and 13–29% with GIM final and rapid products respectively. In simulation kinematic PPP, the convergence time improves 10–43% and 12–25% for final and rapid products respectively. In the kinematic positioning, the addition of external ionospheric constraints may speed up the convergence in the early stage of positioning and improve the accuracy to a certain extent. Among all GIM products, the final products show better performance than that of the rapid products obviously. The GIM products from CAS and CODE and UQRG from UPC express the best performance are recommended to process ionospheric delay in the high-accuracy positioning.
Qiong Wu; Peng Zhang; Mengfei Sun; Shi Liu; He Wang; Shengbo Chen. Performance evaluation of GIMs released by different IGS ionosphere associate analysis centers in ionospheric constrained single-frequency precise point positioning. Advances in Space Research 2020, 1 .
AMA StyleQiong Wu, Peng Zhang, Mengfei Sun, Shi Liu, He Wang, Shengbo Chen. Performance evaluation of GIMs released by different IGS ionosphere associate analysis centers in ionospheric constrained single-frequency precise point positioning. Advances in Space Research. 2020; ():1.
Chicago/Turabian StyleQiong Wu; Peng Zhang; Mengfei Sun; Shi Liu; He Wang; Shengbo Chen. 2020. "Performance evaluation of GIMs released by different IGS ionosphere associate analysis centers in ionospheric constrained single-frequency precise point positioning." Advances in Space Research , no. : 1.
Scale dependence is one of the major characteristics of landscape. Urban landscape is highly affected by human activities with a multi-scale structure, which makes the multi-scale identification of urban structure an obligation for urban spatial studies. Although there have been many previous studies on urban landscape structure, most of them have been conducted on a single scale, and the multi-scale effects of landscape patterns were rarely involved. Two-dimensional wavelet transforms can link spatial structures to scale and spatial locations, and maybe an effective method for the multi-scale analysis of landscape. In this paper, we applied two-dimensional discrete wavelet transform and wavelet variance to analyze the multi-scale spatial structure characteristics and the nested hierarchical structure of the metropolitan Beijing area. The results indicated that the spatial distribution and configuration of the patches were highly scattered at small scales, and the urban landscape exhibited a relatively complicated structure. At medium scales, a combination of the polycentric and sectorial structure was identified due to the prominence of dominant patches within each administrative district. At larger scales, the urban landscape pattern exhibits typical concentric ring characteristics. Two characteristic scales were detected by the wavelet variance in the south-north direction of the main urban zones, scale 4 (112m) and 8 (1792m) in Dongcheng District, scale 3 (56m) and 6 (448m) in Xicheng District, which were corresponding to the extent of middle-small blocks and large blocks respectively. One characteristic scale was detected in each of the suburb areas (Chaoyang, Haidian, and Fengtai District). The spatial structure of the main urban zones is more complex than that of the suburb areas, and it presents a typical hierarchical structure in the south-north direction. In general, the spatial structure of Beijing metropolitan area appears polycentric and concentric ring structure at large scales, the main urban area has nested hierarchies at different characteristic scales, and the wavelet method can effectively identify multi-scale characteristics of urban spatial structure.
Qiong Wu; Jinxiang Tan; Fengxiang Guo; Hongqing Li; Shengbo Chen; Sheng Jiang. Multi-Scale Identification of Urban Landscape Structure Based on Two-Dimensional Wavelet Analysis: The Case of Metropolitan Beijing, China. Ecological Complexity 2020, 43, 100832 .
AMA StyleQiong Wu, Jinxiang Tan, Fengxiang Guo, Hongqing Li, Shengbo Chen, Sheng Jiang. Multi-Scale Identification of Urban Landscape Structure Based on Two-Dimensional Wavelet Analysis: The Case of Metropolitan Beijing, China. Ecological Complexity. 2020; 43 ():100832.
Chicago/Turabian StyleQiong Wu; Jinxiang Tan; Fengxiang Guo; Hongqing Li; Shengbo Chen; Sheng Jiang. 2020. "Multi-Scale Identification of Urban Landscape Structure Based on Two-Dimensional Wavelet Analysis: The Case of Metropolitan Beijing, China." Ecological Complexity 43, no. : 100832.
The selection of an appropriate global gravity field model and refinement method can effectively improve the accuracy of the refined regional geoid model in a certain research area. We analyzed the accuracy of Experimental Geopotential Model (XGM2016) based on the GPS-leveling data and the modification parameters of the global mean square errors in the KTH geoid refinement in Jilin Province, China. The regional geoid was refined based on Earth Gravitational Model (EGM2008) and XGM2016 using both the Helmert condensation method with an RCR procedure and the KTH method. A comparison of the original two gravity field models to the GPS-leveling benchmarks showed that the accuracies of XGM2016 and EGM2008 in the plain area of Jilin Province are similar with a standard deviation (STD) of 5.8 cm, whereas the accuracy of EGM2008 in the high mountainous area is 1.4 cm better than that of XGM2016, which may be attributed to its low resolution. The modification parameters between the two gravity field models showed that the coefficient error of XGM2016 model was lower than that of EGM2008 for the same degree of expansion. The different modification limits and integral radii may produce a centimeter level difference in global mean square error, while the influence of the truncation error caused by the integral was at the millimeter level. The terrestrial gravity data error accounted for the majority of the global mean square error. The optimal least squares modification obtained the minimum global mean square error, and the global mean square error calculated based on XGM2016 model was reduced by about 1~3 cm compared with EGM2008. The refined geoid based on the two gravity field models indicated that both KTH and RCR method can effectively improve the STD of the geoid model from about six to three centimeters. The refined accuracy of EGM2008 model using RCR and KTH methods is slightly better than that of XGM2016 model in the plain and high mountain areas after seven-parameter fitting. EGM2008 based on the KTH method was the most precise at ± 2.0 cm in the plain area and ± 2.4 cm in the mountainous area. Generally, for the refined geoid based on the two Earth gravity models, KTH produced results similar to RCR in the plain area, and had relatively better performance for the mountainous area where terrestrial gravity data is sparse and unevenly distributed.
Qiong Wu; Hongyao Wang; Bin Wang; Shengbo Chen; Hongqing Li. Performance Comparison of Geoid Refinement between XGM2016 and EGM2008 Based on the KTH and RCR Methods: Jilin Province, China. Remote Sensing 2020, 12, 324 .
AMA StyleQiong Wu, Hongyao Wang, Bin Wang, Shengbo Chen, Hongqing Li. Performance Comparison of Geoid Refinement between XGM2016 and EGM2008 Based on the KTH and RCR Methods: Jilin Province, China. Remote Sensing. 2020; 12 (2):324.
Chicago/Turabian StyleQiong Wu; Hongyao Wang; Bin Wang; Shengbo Chen; Hongqing Li. 2020. "Performance Comparison of Geoid Refinement between XGM2016 and EGM2008 Based on the KTH and RCR Methods: Jilin Province, China." Remote Sensing 12, no. 2: 324.
The relationship between urban landscape pattern and land surface temperature (LST) is one of the core issues in urban thermal environment research. Although previous studies have shown a significant correlation between LST and landscape pattern, most were conducted at a single scale and rarely involve multi-scale effects of the landscape pattern. Wavelet coherence can relate the correlation between LST and landscape pattern to spatial scale and location, which is an effective multi-scale correlation method. In this paper, we applied wavelet coherence and Pearson correlation coefficient to analyze the multi-scale correlations between landscape pattern and LST, and analyzed the spatial pattern of the urban thermal environment during the urbanization of Beijing from 2004 to 2017 by distribution index of high-temperature center (HTC). The results indicated that the HTC of Beijing gradually expands from the main urban zone and urban function extended zone to the new urban development zone and far suburb zone, and develops from monocentric to polycentric spatial pattern. Land cover types, such as impervious surfaces and bare land, have a positive contribution to LST, while water and vegetation play a role in mitigating LST. The wavelet coherence and Pearson correlation coefficients showed that landscape composition and spatial configuration have significant effects on LST, but landscape composition has a greater effect on LST in Beijing metropolitan area. Landscape composition indexes (NDBI and NDVI) showed significant multi-scale characteristics with LST, especially at larger scales, which has a strong correlation on the whole transect. There was no significant correlation between the spatial configuration indexes (CONTAG, DIVISION, and LSI) and LST at smaller scales, only at larger scales near the urban area has a significant correlation. With the increase of the scale, Pearson correlation coefficient calculated by spatial rectangle sampling and wavelet coherence coefficient have the same trend, although it had some fluctuations in several locations. However, the wavelet coherence coefficient diagram was smoother and less affected by position and rectangle size, which more conducive to describe the correlation between landscape pattern index and LST at different scales and locations. In general, wavelet coherence provides a multi-scale method to analyze the relationship between landscape pattern and LST, helping to understand urban planning and land management to mitigate the factors affecting urban thermal environment.
Qiong Wu; Jinxiang Tan; Fengxiang Guo; Hongqing Li; Shengbo Chen. Multi-Scale Relationship between Land Surface Temperature and Landscape Pattern Based on Wavelet Coherence: The Case of Metropolitan Beijing, China. Remote Sensing 2019, 11, 3021 .
AMA StyleQiong Wu, Jinxiang Tan, Fengxiang Guo, Hongqing Li, Shengbo Chen. Multi-Scale Relationship between Land Surface Temperature and Landscape Pattern Based on Wavelet Coherence: The Case of Metropolitan Beijing, China. Remote Sensing. 2019; 11 (24):3021.
Chicago/Turabian StyleQiong Wu; Jinxiang Tan; Fengxiang Guo; Hongqing Li; Shengbo Chen. 2019. "Multi-Scale Relationship between Land Surface Temperature and Landscape Pattern Based on Wavelet Coherence: The Case of Metropolitan Beijing, China." Remote Sensing 11, no. 24: 3021.
Yan’an new district (YND) is one of the largest civil engineering projects for land creation in Loess Plateau, of which the amount of earthwork exceeds 600 million m3, to create 78.5 km2 of flat land. Such mega-scale engineering activities and complex geological characteristics have induced wide land deformation in the region. Small baseline subset synthetic aperture radar interferometry (SBAS-InSAR) method and 55 Sentinel-1A (S-1A) images were utilized in the present work to investigate the urban surface deformation in the Yan’an urban area and Yan’an new airport (YNA) from 2015 to 2019. The results were validated by the ground leveling measurements in the YNA. It is found that significant uneven surface deformation existed in both YND and YNA areas with maximum accumulative subsidence of 300 and 217 mm, respectively. Moreover, the average subsidence rate of the YND and YNA areas ranged from −70 to 30 mm/year and −50 to 25 mm/year, respectively. The present work shows that the land deformation suffered two periods (from 2015 to 2017 and from 2017 to 2019) and expanded from urban center to surrounding resettlement area, which are highly relevant with urban earthwork process. It is found that more than 60% of land subsidence occurs at filled areas, while more than 65% of surface uplifting occurs at excavation areas. The present work shows that the subsidence originates from the earth filling and the load of urban buildings, while the release of stress is the major factor for the land uplift. Moreover, it is found that the collapsibility of loess and concentrated precipitation deteriorates the degree of local land subsidence. The deformation discovered by this paper shows that the city may suffer a long period of subsidence, and huge challenges may exist in the period of urban maintaining buildings and infrastructure facilities.
Qiong Wu; Chunting Jia; Shengbo Chen; Hongqing Li. SBAS-InSAR Based Deformation Detection of Urban Land, Created from Mega-Scale Mountain Excavating and Valley Filling in the Loess Plateau: The Case Study of Yan’an City. Remote Sensing 2019, 11, 1673 .
AMA StyleQiong Wu, Chunting Jia, Shengbo Chen, Hongqing Li. SBAS-InSAR Based Deformation Detection of Urban Land, Created from Mega-Scale Mountain Excavating and Valley Filling in the Loess Plateau: The Case Study of Yan’an City. Remote Sensing. 2019; 11 (14):1673.
Chicago/Turabian StyleQiong Wu; Chunting Jia; Shengbo Chen; Hongqing Li. 2019. "SBAS-InSAR Based Deformation Detection of Urban Land, Created from Mega-Scale Mountain Excavating and Valley Filling in the Loess Plateau: The Case Study of Yan’an City." Remote Sensing 11, no. 14: 1673.
The update of the Android system and the emergence of the dual-frequency GNSS chips enable smartphones to acquire dual-frequency GNSS observations. In this paper, the GPS L1/L5 and Galileo E1/E5a dual-frequency PPP (precise point positioning) algorithm based on RTKLIB and GAMP was applied to analyze the positioning performance of the Xiaomi Mi 8 dual-frequency smartphone in static and kinematic modes. The results showed that in the static mode, the RMS position errors of the dual-frequency smartphone PPP solutions in the E, N, and U directions were 21.8 cm, 4.1 cm, and 11.0 cm, respectively, after convergence to 1 m within 102 min. The PPP of dual-frequency smartphone showed similar accuracy with geodetic receiver in single-frequency mode, while geodetic receiver in dual-frequency mode has higher accuracy. In the kinematic mode, the positioning track of the smartphone dual-frequency data had severe fluctuations, the positioning tracks derived from the smartphone and the geodetic receiver showed approximately difference of 3–5 m.
Qiong Wu; Mengfei Sun; Changjie Zhou; Peng Zhang. Precise Point Positioning Using Dual-Frequency GNSS Observations on Smartphone. Sensors 2019, 19, 2189 .
AMA StyleQiong Wu, Mengfei Sun, Changjie Zhou, Peng Zhang. Precise Point Positioning Using Dual-Frequency GNSS Observations on Smartphone. Sensors. 2019; 19 (9):2189.
Chicago/Turabian StyleQiong Wu; Mengfei Sun; Changjie Zhou; Peng Zhang. 2019. "Precise Point Positioning Using Dual-Frequency GNSS Observations on Smartphone." Sensors 19, no. 9: 2189.
Landscapes display overlapping sets of correlations in different regions at different spatial scales, and these correlations can be delineated by pattern analysis. This study identified the correlations between landscape pattern and topography at various scales and locations in urban-rural profiles from Jilin City, China, using Pearson correlation analysis and wavelet method. Two profiles, 30 km (A) and 35 km (B) in length with 0.1-km sampling intervals, were selected. The results indicated that profile A was more sensitive to the characterization of the land use pattern as influenced by topography due to its more varied terrain, and three scales (small, medium, and large) could be defined based on the variation in the standard deviation of the wavelet coherency in profile A. Correlations between landscape metrics and elevation were similar at large scales (over 8 km), while complex correlations were discovered at other scale intervals. The medium scale of cohesion and Shannon’s diversity index was 1–8 km, while those of perimeter-area fractal dimension and edge density index were 1.5–8 km and 2–8 km, respectively. At small scales, the correlations were weak as a whole and scattered due to the micro-topography and landform elements, such as valleys and hillsides. At medium scales, the correlations were most affected by local topography, and the land use pattern was significantly correlated with topography at several locations. At large spatial scales, significant correlation existed throughout the study area due to alternating mountains and plains. In general, the strength of correlation between landscape metrics and topography increased gradually with increasing spatial scale, although this tendency had some fluctuations in several locations. Despite a complex calculating process and ecological interpretation, the wavelet method is still an effective tool to identify multi-scale characteristics in landscape ecology.
Qiong Wu; Fengxiang Guo; Hongqing Li. Wavelet-Based Correlation Identification of Scales and Locations between Landscape Patterns and Topography in Urban-Rural Profiles: Case of the Jilin City, China. Remote Sensing 2018, 10, 1653 .
AMA StyleQiong Wu, Fengxiang Guo, Hongqing Li. Wavelet-Based Correlation Identification of Scales and Locations between Landscape Patterns and Topography in Urban-Rural Profiles: Case of the Jilin City, China. Remote Sensing. 2018; 10 (10):1653.
Chicago/Turabian StyleQiong Wu; Fengxiang Guo; Hongqing Li. 2018. "Wavelet-Based Correlation Identification of Scales and Locations between Landscape Patterns and Topography in Urban-Rural Profiles: Case of the Jilin City, China." Remote Sensing 10, no. 10: 1653.
The Continuously Operating Reference Station (CORS) technique has been widely applied in land resource management, surveying, mapping, deformation monitoring, precise navigation, etc. This article analyzed the positioning method using EGM2008 and CORS of Jilin Province, China. The vertical transformation of EGM2008 from WGS84 to China’s CGCS2000 datum and the horizontal coordinate transformation from CGCS2000 to a triangulation coordinate system were discussed. The results indicated that a local geoid with respect to CGCS2000 can be transferred from EGM2008 with the same accuracy, and the geoid correction between CGCS2000 and WGS84 varied from 0.023 m to 0.111 m. The coordinate transformation method based on the curve surface approximation method indicated that the theoretical error was less than 0.09 m in the grid within 10° longitudinal and 5° latitudinal, and less than 0.3 m in large area and 0.1 m in small area in field validation. The method proposed in this article expanded the positioning result and its application for JLCORS and other CORS with local datum.
Qiong Wu; Jingyu Kang; Shuwen Li; Jianing Zhen; Hongqing Li. GNSS Positioning by CORS and EGM2008 in Jilin Province, China. Sensors 2015, 15, 30419 -30428.
AMA StyleQiong Wu, Jingyu Kang, Shuwen Li, Jianing Zhen, Hongqing Li. GNSS Positioning by CORS and EGM2008 in Jilin Province, China. Sensors. 2015; 15 (12):30419-30428.
Chicago/Turabian StyleQiong Wu; Jingyu Kang; Shuwen Li; Jianing Zhen; Hongqing Li. 2015. "GNSS Positioning by CORS and EGM2008 in Jilin Province, China." Sensors 15, no. 12: 30419-30428.
Qian Yang -; Shengbo Chen -; Peng Lu -; Mingchang Wang -; Qiong Wu -; Chao Zhou -; Yanli Liu -. Unmanned Airship Based High Resolution Images Acquisition and the Processing. International Journal of Advancements in Computing Technology 2013, 5, 379 -386.
AMA StyleQian Yang -, Shengbo Chen -, Peng Lu -, Mingchang Wang -, Qiong Wu -, Chao Zhou -, Yanli Liu -. Unmanned Airship Based High Resolution Images Acquisition and the Processing. International Journal of Advancements in Computing Technology. 2013; 5 (3):379-386.
Chicago/Turabian StyleQian Yang -; Shengbo Chen -; Peng Lu -; Mingchang Wang -; Qiong Wu -; Chao Zhou -; Yanli Liu -. 2013. "Unmanned Airship Based High Resolution Images Acquisition and the Processing." International Journal of Advancements in Computing Technology 5, no. 3: 379-386.
Remote sensing and GIS have been widely employed to study temporal and spatial urban land use changes in southern and southeastern China. However, few studies have been conducted in northeastern regions. This study analyzed land use change and spatial patterns of urban expansion in the metropolitan area of Jilin City, located on the extension of Changbai Mountain, based on aerial photos from 1989 and 2005 Spot images. The results indicated that urban land and transportation land increased dramatically (by 94.04% and 211.20%, respectively); isolated industrial and mining land decreased moderately (by 29.54%); rural residential land increased moderately (by 26.48%); dry land and paddy fields increased slightly (by 15.68% and 11.78%, respectively); forest and orchards decreased slightly (by 5.27% and 4.61%, respectively); grasslands and unused land decreased dramatically (by 99.12% and 86.04%, respectively). Sloped dry land (more than 4 degrees) was mainly distributed on the land below 10 degrees with an east, southeastern and south sunny direction aspect, and most sloped dry land transformed to forest was located on an east aspect lower than 12 degrees, while forest changed to dry land were mainly distributed on east and south aspects lower than 10 degrees. A spatial dependency analysis of land use change showed that the increased urban land was a logarithmic function of distance to the Songhua River. This study also provided some data with spatial details about the uneven land development in the upstream areas of Songhua River basin.
Dan Hu; Guodong Yang; Qiong Wu; Hongqing Li; Xusheng Liu; Xuefeng Niu; Zhiheng Wang; Qiong Wang. Analyzing Land Use Changes in the Metropolitan Jilin City of Northeastern China Using Remote Sensing and GIS. Sensors 2008, 8, 5449 -5465.
AMA StyleDan Hu, Guodong Yang, Qiong Wu, Hongqing Li, Xusheng Liu, Xuefeng Niu, Zhiheng Wang, Qiong Wang. Analyzing Land Use Changes in the Metropolitan Jilin City of Northeastern China Using Remote Sensing and GIS. Sensors. 2008; 8 (9):5449-5465.
Chicago/Turabian StyleDan Hu; Guodong Yang; Qiong Wu; Hongqing Li; Xusheng Liu; Xuefeng Niu; Zhiheng Wang; Qiong Wang. 2008. "Analyzing Land Use Changes in the Metropolitan Jilin City of Northeastern China Using Remote Sensing and GIS." Sensors 8, no. 9: 5449-5465.
Qiong Wu; Rusong Wang; Hongqing Li; Paulussen Juergen; Yong He; Bihui Wang. [Statistical properties of Markov chain in land use and landscape study]. Ying yong sheng tai xue bao = The journal of applied ecology 2006, 17, 434 -7.
AMA StyleQiong Wu, Rusong Wang, Hongqing Li, Paulussen Juergen, Yong He, Bihui Wang. [Statistical properties of Markov chain in land use and landscape study]. Ying yong sheng tai xue bao = The journal of applied ecology. 2006; 17 (3):434-7.
Chicago/Turabian StyleQiong Wu; Rusong Wang; Hongqing Li; Paulussen Juergen; Yong He; Bihui Wang. 2006. "[Statistical properties of Markov chain in land use and landscape study]." Ying yong sheng tai xue bao = The journal of applied ecology 17, no. 3: 434-7.