Abstract A large systematic difference (ranging from −20 cm to +130 cm) was found between NAVD 88 (North AmericanVertical Datum of 1988) and the pure gravimetric geoid models. This difference not only makes it very difficult to augment the local geoid model by directly using the vast NAVD 88 network with state-of-the-art technologies recently developed in geodesy, but also limits the ability of researchers to effectively demonstrate the geoid model improvements on the NAVD 88 network. Here, both conventional regression analyses based on various predefined basis functions such as polynomials, B-splines, and Legendre functions and the Latent Variable Analysis (LVA) such as the Factor Analysis (FA) are used to analyze the systematic difference. Besides giving a mathematical model, the regression results do not reveal a great deal about the physical reasons that caused the large differences in NAVD 88, which may be of interest to various researchers. Furthermore, there is still a significant amount of no-Gaussian signals left in the residuals of the conventional regression models. On the other side, the FA method not only provides a better not of the data, but also offers possible explanations of the error sources. Without requiring extra hypothesis tests on the model coefficients, the results from FA are more efficient in terms of capturing the systematic difference. Furthermore, without using a covariance model, a novel interpolating method based on the relationship between the loading matrix and the factor scores is developed for predictive purposes. The prediction error analysis shows that about 3-7 cm precision is expected in NAVD 88 after removing the systematic difference.
NAVD 88 (North AmericanVertical Datum of 1988)与纯重力大地水准面模型存在较大的系统差异(- 20 ~ +130 cm)。这种差异不仅使得直接使用庞大的NAVD 88网络与最新的大地测量学技术来增强局部大地水准面模型非常困难，而且也限制了研究人员在NAVD 88网络上有效展示大地水准面模型改进的能力。在这里，基于各种预定义基函数(如多项式、b样条和勒让德函数)的传统回归分析和潜在变量分析(LVA)(如因子分析(FA))都被用于分析系统差异。除了给出一个数学模型外，回归结果并没有揭示导致NAVD 88差异巨大的物理原因，这可能会引起各种研究人员的兴趣。此外，在传统回归模型的残差中仍然存在大量的非高斯信号。另一方面，FA方法不仅提供了更好的数据，而且还提供了对误差来源的可能解释。在不需要对模型系数进行额外的假设检验的情况下，FA的结果在捕获系统差异方面更有效。此外，在不使用协方差模型的情况下，提出了一种基于负荷矩阵与因子得分之间关系的预测插值方法。预测误差分析表明，去除系统差异后，NAVD 88的预测精度约为3 ~ 7cm。
{"title":"Modeling the North American vertical datum of 1988 errors in the conterminous United States","authors":"X. Li","doi":"10.1515/jogs-2018-0001","DOIUrl":"https://doi.org/10.1515/jogs-2018-0001","url":null,"abstract":"Abstract A large systematic difference (ranging from −20 cm to +130 cm) was found between NAVD 88 (North AmericanVertical Datum of 1988) and the pure gravimetric geoid models. This difference not only makes it very difficult to augment the local geoid model by directly using the vast NAVD 88 network with state-of-the-art technologies recently developed in geodesy, but also limits the ability of researchers to effectively demonstrate the geoid model improvements on the NAVD 88 network. Here, both conventional regression analyses based on various predefined basis functions such as polynomials, B-splines, and Legendre functions and the Latent Variable Analysis (LVA) such as the Factor Analysis (FA) are used to analyze the systematic difference. Besides giving a mathematical model, the regression results do not reveal a great deal about the physical reasons that caused the large differences in NAVD 88, which may be of interest to various researchers. Furthermore, there is still a significant amount of no-Gaussian signals left in the residuals of the conventional regression models. On the other side, the FA method not only provides a better not of the data, but also offers possible explanations of the error sources. Without requiring extra hypothesis tests on the model coefficients, the results from FA are more efficient in terms of capturing the systematic difference. Furthermore, without using a covariance model, a novel interpolating method based on the relationship between the loading matrix and the factor scores is developed for predictive purposes. The prediction error analysis shows that about 3-7 cm precision is expected in NAVD 88 after removing the systematic difference.","PeriodicalId":44569,"journal":{"name":"Journal of Geodetic Science","volume":"3 1","pages":"1 - 13"},"PeriodicalIF":1.3,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79218502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Sidereal filtering is the name of a technique used to reduce the effect of multipath interference on a GPS position time series associated with a static or quasi-static antenna. This article assesses the impact of a GPS satellite outage on the performance of a sidereal filter. Two different types of sidereal filter are tested: a position-domain sidereal filter (PDSF) and an observation-domain sidereal filter (ODSF). A satellite outage is simulated at two static receivers with contrasting antenna types and multipath environments. At both stations, the ODSF is more effective than a PDSF at removing multipath error over averaging intervals under around 200 seconds in length whether there is an outage or not. However, difference in the performance of the two types of sidereal filter was much more significant at the station more prone to multipath interference. The results are particularly relevant for applications where high-rate precise point positioning (PPP) is used for monitoring: If a PDSF is applied, then errors due to highfrequency multipath interference may still alias into the resulting position time series if a satellite outage occurs and possibly increasing the false alarm rate. In contrast, an ODSF is likely to perform better in such circumstances.
{"title":"Performance of GPS sidereal filters during a satellite outage","authors":"C. Atkins, M. Ziebart","doi":"10.1515/jogs-2017-0015","DOIUrl":"https://doi.org/10.1515/jogs-2017-0015","url":null,"abstract":"Abstract Sidereal filtering is the name of a technique used to reduce the effect of multipath interference on a GPS position time series associated with a static or quasi-static antenna. This article assesses the impact of a GPS satellite outage on the performance of a sidereal filter. Two different types of sidereal filter are tested: a position-domain sidereal filter (PDSF) and an observation-domain sidereal filter (ODSF). A satellite outage is simulated at two static receivers with contrasting antenna types and multipath environments. At both stations, the ODSF is more effective than a PDSF at removing multipath error over averaging intervals under around 200 seconds in length whether there is an outage or not. However, difference in the performance of the two types of sidereal filter was much more significant at the station more prone to multipath interference. The results are particularly relevant for applications where high-rate precise point positioning (PPP) is used for monitoring: If a PDSF is applied, then errors due to highfrequency multipath interference may still alias into the resulting position time series if a satellite outage occurs and possibly increasing the false alarm rate. In contrast, an ODSF is likely to perform better in such circumstances.","PeriodicalId":44569,"journal":{"name":"Journal of Geodetic Science","volume":"26 1","pages":"141 - 150"},"PeriodicalIF":1.3,"publicationDate":"2017-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89831863","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The existence of hardware induced phase biases might influence the accuracy in precise positioning if not handled properly. This is extra problematic if the biases are dependent on the satellite tracked, as these biases no longer will be common between the satellites, and thus will not be absorbed by the receiver clock term of the positioning solution. In this paper, we carried out two studies to investigate whether there exists a satellite dependency of the relative phase biases. Even though small in size, satellite dependent variations were found in both cases. In the first case, relative receiver phase biases were studied, while relative phase biases between signals (e.g. between carrier phases from C/A-code and P-code tracking) were investigated in the second case. The biases in the first case had a size of 0.8 mm between the satellites with the largest and smallest values, and additionally showed temporal variations that were consistent over time. The corresponding sizes of the biases second case were 2 mm and 3.5 mm for GPS L1 and L2 respectively, and no temporal variations were found.
{"title":"Satellite dependency of GNSS phase biases between receivers and between signals","authors":"M. Håkansson","doi":"10.1515/jogs-2017-0014","DOIUrl":"https://doi.org/10.1515/jogs-2017-0014","url":null,"abstract":"Abstract The existence of hardware induced phase biases might influence the accuracy in precise positioning if not handled properly. This is extra problematic if the biases are dependent on the satellite tracked, as these biases no longer will be common between the satellites, and thus will not be absorbed by the receiver clock term of the positioning solution. In this paper, we carried out two studies to investigate whether there exists a satellite dependency of the relative phase biases. Even though small in size, satellite dependent variations were found in both cases. In the first case, relative receiver phase biases were studied, while relative phase biases between signals (e.g. between carrier phases from C/A-code and P-code tracking) were investigated in the second case. The biases in the first case had a size of 0.8 mm between the satellites with the largest and smallest values, and additionally showed temporal variations that were consistent over time. The corresponding sizes of the biases second case were 2 mm and 3.5 mm for GPS L1 and L2 respectively, and no temporal variations were found.","PeriodicalId":44569,"journal":{"name":"Journal of Geodetic Science","volume":"30 1","pages":"130 - 140"},"PeriodicalIF":1.3,"publicationDate":"2017-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89284711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Least-squares estimates are trustworthy with minimal variance if the correct stochastic model is used. Due to computational burden, diagonal models that neglect correlations are preferred to describe the elevation dependency of the variance of GPS observations. In this contribution, an improved stochastic model based on a parametric function to take correlations between GPS phase observations into account is presented. Built on an adapted and flexible Mátern function accounting for spatiotemporal variabilities, its parameters can be fixed thanks to Maximum Likelihood Estimation or chosen apriori to model turbulent tropospheric refractivity fluctuations. In this contribution, we will show in which cases and under which conditions corresponding fully populated variance covariance matrices (VCM) replace the estimation of a tropospheric parameter. For this equivalence “augmented functional versus augmented stochastic model” to hold, the VCM should be made sufficiently largewhich corresponds to computing small batches of observations. A case study with observations from a medium baseline of 80 km divided into batches of 600 s shows improvement of up to 100 mm for the 3Drms when fully populated VCM are used compared with an elevation dependent diagonal model. It confirms the strong potential of such matrices to improve the least-squares solution, particularly when ambiguities are let float.
{"title":"Fully populated VCM or the hidden parameter","authors":"G. Kermarrec, S. Schön","doi":"10.1515/jogs-2017-0016","DOIUrl":"https://doi.org/10.1515/jogs-2017-0016","url":null,"abstract":"Abstract Least-squares estimates are trustworthy with minimal variance if the correct stochastic model is used. Due to computational burden, diagonal models that neglect correlations are preferred to describe the elevation dependency of the variance of GPS observations. In this contribution, an improved stochastic model based on a parametric function to take correlations between GPS phase observations into account is presented. Built on an adapted and flexible Mátern function accounting for spatiotemporal variabilities, its parameters can be fixed thanks to Maximum Likelihood Estimation or chosen apriori to model turbulent tropospheric refractivity fluctuations. In this contribution, we will show in which cases and under which conditions corresponding fully populated variance covariance matrices (VCM) replace the estimation of a tropospheric parameter. For this equivalence “augmented functional versus augmented stochastic model” to hold, the VCM should be made sufficiently largewhich corresponds to computing small batches of observations. A case study with observations from a medium baseline of 80 km divided into batches of 600 s shows improvement of up to 100 mm for the 3Drms when fully populated VCM are used compared with an elevation dependent diagonal model. It confirms the strong potential of such matrices to improve the least-squares solution, particularly when ambiguities are let float.","PeriodicalId":44569,"journal":{"name":"Journal of Geodetic Science","volume":"254 1","pages":"151 - 161"},"PeriodicalIF":1.3,"publicationDate":"2017-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73541424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract For an adjustment of a similarity transformation, it is often appropriate to consider that both the source and the target coordinates of the transformation are affected by errors. For the least squares adjustment of this problem, a direct solution is possible in the cases of specific-weighing schemas of the coordinates. Such a problem is considered in the present contribution and a direct solution is generally derived for the m-dimensional space. The applied weighing schema allows (fully populated) point-wise weight matrices for the source and target coordinates, both weight matrices have to be proportional to each other. Additionally, the solutions of two borderline cases of this weighting schema are derived, which only consider errors in the source or target coordinates. The investigated solution of the rotation matrix of the adjustment is independent of the scaling between the weight matrices of the source and the target coordinates. The mentioned borderline cases, therefore, have the same solution of the rotation matrix. The direct solution method is successfully tested on an example of a 3D similarity transformation using a comparison with an iterative solution based on the Gauß-Helmert model.
{"title":"A weighted adjustment of a similarity transformation between two point sets containing errors","authors":"C. Marx","doi":"10.1515/jogs-2017-0012","DOIUrl":"https://doi.org/10.1515/jogs-2017-0012","url":null,"abstract":"Abstract For an adjustment of a similarity transformation, it is often appropriate to consider that both the source and the target coordinates of the transformation are affected by errors. For the least squares adjustment of this problem, a direct solution is possible in the cases of specific-weighing schemas of the coordinates. Such a problem is considered in the present contribution and a direct solution is generally derived for the m-dimensional space. The applied weighing schema allows (fully populated) point-wise weight matrices for the source and target coordinates, both weight matrices have to be proportional to each other. Additionally, the solutions of two borderline cases of this weighting schema are derived, which only consider errors in the source or target coordinates. The investigated solution of the rotation matrix of the adjustment is independent of the scaling between the weight matrices of the source and the target coordinates. The mentioned borderline cases, therefore, have the same solution of the rotation matrix. The direct solution method is successfully tested on an example of a 3D similarity transformation using a comparison with an iterative solution based on the Gauß-Helmert model.","PeriodicalId":44569,"journal":{"name":"Journal of Geodetic Science","volume":"10 1","pages":"105 - 112"},"PeriodicalIF":1.3,"publicationDate":"2017-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84926150","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The present study investigates the crustal strain in Turkey by using data from the Turkish permanent GNSS network (TPGN) and international GNSS services (IGS) observations for a period of 9 years, 2009 t0 2017. The positional variation of GNSS sites is studied to understand the coordinate reliability, interseismic and coseismic effects and linear velocities as well as three dimensional principal strains across the country. The study of coordinate reliability shows that the horizontal and vertical residuals in 2013 and 2015 are of the order of 100 mm per coordinate or higher than those of 2009 and 2011 and 10 times higher than those of 2017. The changes in baseline length relative to an arbitrary zero-o_set for the selected period shows that the most of the sites have displacement in the interval −10 to 10 mm but some sites have larger variations. These displacements are mostly related to motion of the Turkish tectonic plate, regional crustal deformation and small amounts of errors inGNSS positioning. The most GNSS site velocities located all over Turkey give significant information for the study. The GNSS data shows that the Anatolian plate relative to the Eurasia is moving in a western direction in the central part of Turkey and starts to move in a south-westerly direction in the west part of the country. The westward motion of Anatolia increases gradually from 20 mm/yr in central Anatolia to 30 mm/yr in south-west Turkey. The numerical simulation of the crustal strain in the Aegean region shows a maximum 1.0446×10−6 compressional principal strain rate while the second principal strain rate is zero. The strain in Central Anatolia is evidently dominated by extensional deformations and the principal strain rate reaches to 0.9589×10−6 with maximum extension. The Marmara Region network is subject to an extensional principal strain (0.6608×10−6) which is also revealed in the Mediterranean Region with a 0.5682×10−6 extension. The present analysis of GNSS data over the region may complement towards the understanding of the stability of regional tectonics and long term aseismic strain inside the country.
{"title":"Numerical Simulation of Crustal Strain in Turkey from Continuous GNSS Measurements in the Interval 2009–2017","authors":"K. Ansari, O. Corumluoglu, S. Sharma","doi":"10.1515/jogs-2017-0013","DOIUrl":"https://doi.org/10.1515/jogs-2017-0013","url":null,"abstract":"Abstract The present study investigates the crustal strain in Turkey by using data from the Turkish permanent GNSS network (TPGN) and international GNSS services (IGS) observations for a period of 9 years, 2009 t0 2017. The positional variation of GNSS sites is studied to understand the coordinate reliability, interseismic and coseismic effects and linear velocities as well as three dimensional principal strains across the country. The study of coordinate reliability shows that the horizontal and vertical residuals in 2013 and 2015 are of the order of 100 mm per coordinate or higher than those of 2009 and 2011 and 10 times higher than those of 2017. The changes in baseline length relative to an arbitrary zero-o_set for the selected period shows that the most of the sites have displacement in the interval −10 to 10 mm but some sites have larger variations. These displacements are mostly related to motion of the Turkish tectonic plate, regional crustal deformation and small amounts of errors inGNSS positioning. The most GNSS site velocities located all over Turkey give significant information for the study. The GNSS data shows that the Anatolian plate relative to the Eurasia is moving in a western direction in the central part of Turkey and starts to move in a south-westerly direction in the west part of the country. The westward motion of Anatolia increases gradually from 20 mm/yr in central Anatolia to 30 mm/yr in south-west Turkey. The numerical simulation of the crustal strain in the Aegean region shows a maximum 1.0446×10−6 compressional principal strain rate while the second principal strain rate is zero. The strain in Central Anatolia is evidently dominated by extensional deformations and the principal strain rate reaches to 0.9589×10−6 with maximum extension. The Marmara Region network is subject to an extensional principal strain (0.6608×10−6) which is also revealed in the Mediterranean Region with a 0.5682×10−6 extension. The present analysis of GNSS data over the region may complement towards the understanding of the stability of regional tectonics and long term aseismic strain inside the country.","PeriodicalId":44569,"journal":{"name":"Journal of Geodetic Science","volume":"29 1","pages":"113 - 129"},"PeriodicalIF":1.3,"publicationDate":"2017-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81908880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract This paper describes the reconstruction of postflight trajectories of suborbital free flying units by using logged GPS raw data. We took the reconstruction as a global least squares optimization problem, using both the pseudo-range and Doppler observables, and solved it by using the trust-region-reflective algorithm, which enabled navigational solutions of high accuracy. The code tracking was implemented with a large number of correlators and least squares curve fitting, in order to improve the precision of the code start times, while a more conventional phased lock loop was used for Doppler tracking. We proposed a weighting scheme to account for fast signal strength variation due to free-flier fast rotation, and a penalty for jerk to achieve a smooth solution. We applied these methods to flight data of two suborbital free flying units launched on REXUS 12 sounding rocket, reconstructing the trajectory, receiver clock error and wind up rates. The trajectory exhibits a parabola with the apogee around 80 km, and the velocity profile shows the details of payloadwobbling. The wind up rates obtained match the measurements from onboard angular rate sensors.
{"title":"Post-flight trajectory reconstruction of suborbital free-flyers using GPS raw data","authors":"N. Ivchenko, Y. Yuan, E. Lindén","doi":"10.1515/jogs-2017-0011","DOIUrl":"https://doi.org/10.1515/jogs-2017-0011","url":null,"abstract":"Abstract This paper describes the reconstruction of postflight trajectories of suborbital free flying units by using logged GPS raw data. We took the reconstruction as a global least squares optimization problem, using both the pseudo-range and Doppler observables, and solved it by using the trust-region-reflective algorithm, which enabled navigational solutions of high accuracy. The code tracking was implemented with a large number of correlators and least squares curve fitting, in order to improve the precision of the code start times, while a more conventional phased lock loop was used for Doppler tracking. We proposed a weighting scheme to account for fast signal strength variation due to free-flier fast rotation, and a penalty for jerk to achieve a smooth solution. We applied these methods to flight data of two suborbital free flying units launched on REXUS 12 sounding rocket, reconstructing the trajectory, receiver clock error and wind up rates. The trajectory exhibits a parabola with the apogee around 80 km, and the velocity profile shows the details of payloadwobbling. The wind up rates obtained match the measurements from onboard angular rate sensors.","PeriodicalId":44569,"journal":{"name":"Journal of Geodetic Science","volume":"9 1","pages":"104 - 94"},"PeriodicalIF":1.3,"publicationDate":"2017-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90597167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract In this study, a hydrographic map of a South Florida canal is prepared using RTK GPS (Real Time Kinematic Global Positioning System) measurements combined with a hydrolite (single beam echo sounder). RTK GPS measurements are made using both single RTK and Network RTK systems. Digital sounding measurements taken by hydrolite are compared to manual lead line measurements. Single RTK and Network RTK results differed in the order of tenth of a foot accuracy for horizontal coordinates and for height measurements variations can go up to several tenths. Sounding results indicate a best-fit trend line with a slope of 0.993, and an R squared value of 0.972, demonstrating that hydrolite measurements and manually collected depths at this site are well correlated.
{"title":"Hydrographic survey of a south Florida canal using a hydrolite","authors":"M. Berber, W. Wright","doi":"10.1515/jogs-2017-0009","DOIUrl":"https://doi.org/10.1515/jogs-2017-0009","url":null,"abstract":"Abstract In this study, a hydrographic map of a South Florida canal is prepared using RTK GPS (Real Time Kinematic Global Positioning System) measurements combined with a hydrolite (single beam echo sounder). RTK GPS measurements are made using both single RTK and Network RTK systems. Digital sounding measurements taken by hydrolite are compared to manual lead line measurements. Single RTK and Network RTK results differed in the order of tenth of a foot accuracy for horizontal coordinates and for height measurements variations can go up to several tenths. Sounding results indicate a best-fit trend line with a slope of 0.993, and an R squared value of 0.972, demonstrating that hydrolite measurements and manually collected depths at this site are well correlated.","PeriodicalId":44569,"journal":{"name":"Journal of Geodetic Science","volume":"24 1","pages":"79 - 83"},"PeriodicalIF":1.3,"publicationDate":"2017-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90924408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract This study demonstrates that relative sea level trends calculated from long-term tide gauge records can be used to estimate relative vertical crustal velocities in a region with high accuracy. A comparison of the weighted averages of the relative sea level trends estimated at six tide gauge stations in two clusters along the Eastern coast of United States, in Florida and in Maryland, reveals a statistically significant regional vertical crustal motion of Maryland with respect to Florida with a subsidence rate of −1.15±0.15 mm/yr identified predominantly due to the ongoing glacial isostatic adjustment process. The estimate is a consilience value to validate vertical crustal velocities calculated from GPS time series as well as towards constraining predictive GIA models in these regions.
{"title":"Inferring regional vertical crustal velocities from averaged relative sea level trends: A proof of concept","authors":"H. Iz, C. Shum, C. Zhang, C. Kuo","doi":"10.1515/jogs-2017-0007","DOIUrl":"https://doi.org/10.1515/jogs-2017-0007","url":null,"abstract":"Abstract This study demonstrates that relative sea level trends calculated from long-term tide gauge records can be used to estimate relative vertical crustal velocities in a region with high accuracy. A comparison of the weighted averages of the relative sea level trends estimated at six tide gauge stations in two clusters along the Eastern coast of United States, in Florida and in Maryland, reveals a statistically significant regional vertical crustal motion of Maryland with respect to Florida with a subsidence rate of −1.15±0.15 mm/yr identified predominantly due to the ongoing glacial isostatic adjustment process. The estimate is a consilience value to validate vertical crustal velocities calculated from GPS time series as well as towards constraining predictive GIA models in these regions.","PeriodicalId":44569,"journal":{"name":"Journal of Geodetic Science","volume":"71 1","pages":"59 - 67"},"PeriodicalIF":1.3,"publicationDate":"2017-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86243609","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Jamil, M. Kadir, R. Forsberg, A. Olesen, M. N. Isa, S. Rasidi, A. Mohamed, Z. Chihat, E. Nielsen, F. Majid, K. Talib, SAIFUL AMAN Bin HJ SULAIMAN
Abstract This paper describes the development of a new geoid-based vertical datum from airborne gravity data, by the Department of Survey and Mapping Malaysia, on land and in the South China Sea out of the coast of East Malaysia region, covering an area of about 610,000 square kilometres. More than 107,000 km flight line of airborne gravity data over land and marine areas of East Malaysia has been combined to provide a seamless land-to-sea gravity field coverage; with an estimated accuracy of better than 2.0 mGal. The iMAR-IMU processed gravity anomaly data has been used during a 2014-2016 airborne survey to extend a composite gravity solution across a number of minor gaps on selected lines, using a draping technique. The geoid computations were all done with the GRAVSOFT suite of programs from DTU-Space. EGM2008 augmented with GOCE spherical harmonic model has been used to spherical harmonic degree N = 720. The gravimetric geoid first was tied at one tide-gauge (in Kota Kinabalu, KK2019) to produce a fitted geoid, my_geoid2017_fit_kk. The fitted geoid was offset from the gravimetric geoid by +0.852 m, based on the comparison at the tide-gauge benchmark KK2019. Consequently, orthometric height at the six other tide gauge stations was computed from HGPS Lev = hGPS - Nmy_geoid2017_.t_kk. Comparison of the conventional (HLev) and GPS-levelling heights (HGPS Lev) at the six tide gauge locations indicate RMS height difference of 2.6 cm. The final gravimetric geoidwas fitted to the seven tide gauge stations and is known as my_geoid2017_fit_east. The accuracy of the gravimetric geoid is estimated to be better than 5 cm across most of East Malaysia land and marine areas
{"title":"Airborne geoid mapping of land and sea areas of East Malaysia","authors":"H. Jamil, M. Kadir, R. Forsberg, A. Olesen, M. N. Isa, S. Rasidi, A. Mohamed, Z. Chihat, E. Nielsen, F. Majid, K. Talib, SAIFUL AMAN Bin HJ SULAIMAN","doi":"10.1515/jogs-2017-0010","DOIUrl":"https://doi.org/10.1515/jogs-2017-0010","url":null,"abstract":"Abstract This paper describes the development of a new geoid-based vertical datum from airborne gravity data, by the Department of Survey and Mapping Malaysia, on land and in the South China Sea out of the coast of East Malaysia region, covering an area of about 610,000 square kilometres. More than 107,000 km flight line of airborne gravity data over land and marine areas of East Malaysia has been combined to provide a seamless land-to-sea gravity field coverage; with an estimated accuracy of better than 2.0 mGal. The iMAR-IMU processed gravity anomaly data has been used during a 2014-2016 airborne survey to extend a composite gravity solution across a number of minor gaps on selected lines, using a draping technique. The geoid computations were all done with the GRAVSOFT suite of programs from DTU-Space. EGM2008 augmented with GOCE spherical harmonic model has been used to spherical harmonic degree N = 720. The gravimetric geoid first was tied at one tide-gauge (in Kota Kinabalu, KK2019) to produce a fitted geoid, my_geoid2017_fit_kk. The fitted geoid was offset from the gravimetric geoid by +0.852 m, based on the comparison at the tide-gauge benchmark KK2019. Consequently, orthometric height at the six other tide gauge stations was computed from HGPS Lev = hGPS - Nmy_geoid2017_.t_kk. Comparison of the conventional (HLev) and GPS-levelling heights (HGPS Lev) at the six tide gauge locations indicate RMS height difference of 2.6 cm. The final gravimetric geoidwas fitted to the seven tide gauge stations and is known as my_geoid2017_fit_east. The accuracy of the gravimetric geoid is estimated to be better than 5 cm across most of East Malaysia land and marine areas","PeriodicalId":44569,"journal":{"name":"Journal of Geodetic Science","volume":"42 1","pages":"84 - 93"},"PeriodicalIF":1.3,"publicationDate":"2017-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77992927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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