High Resolution Technology of Shuttle Radar Topography Mission for Geoid Model

2017 ◽  
Keyword(s):  
High Resolution ◽  
Shuttle Radar Topography Mission ◽  
Geoid Model

scholarly journals A High-Resolution Gravimetric Geoid Model for Kuwait Using the Least-Squares Collocation

2022 ◽  
Vol 9 ◽  
Author(s):  
Hamad Al-Ajami ◽  
Ahmed Zaki ◽  
Mostafa Rabah ◽  
Mohamed El-Ashquer
Keyword(s):  
High Resolution ◽  
Least Squares ◽  
Geopotential Model ◽  
Gravimetric Geoid ◽  
Least Squares Collocation ◽  
Geoid Model ◽  
Terrestrial Gravity ◽  
Digital Elevation ◽  
Elevation Model ◽  
Gps Leveling

A new gravimetric geoid model, the KW-FLGM2021, is developed for Kuwait in this study. This new geoid model is driven by a combination of the XGM2019e-combined global geopotential model (GGM), terrestrial gravity, and the SRTM 3 global digital elevation model with a spatial resolution of three arc seconds. The KW-FLGM2021 has been computed by using the technique of Least Squares Collocation (LSC) with Remove-Compute-Restore (RCR) procedure. To evaluate the external accuracy of the KW-FLGM2021 gravimetric geoid model, GPS/leveling data were used. As a result of this evaluation, the residual of geoid heights obtained from the KW-FLGM2021 geoid model is 2.2 cm. The KW-FLGM2021 is possible to be recommended as the first accurate geoid model for Kuwait.

Comparison of Dynamic Topography Bias in HIROMB and NEMO-Nordic Model by Utilizing Marine Geoid

2020 ◽  
Author(s):  
Vahidreza Jahanmard ◽  
Nicole Delpeche-Ellmann ◽  
Artu Ellmann
Keyword(s):  
High Resolution ◽  
Reference Frame ◽  
Tide Gauge ◽  
Equipotential Surface ◽  
Geodetic Reference System ◽  
Dynamic Topography ◽  
Tide Gauges ◽  
Geoid Model ◽  
The North ◽  
The Baltic

<p>Hydrodynamic models (HDM) provide a reasonable estimate of the sea conditions. Thus making them a vital tool for climate change, engineering, and marine ecosystems. One of the parameters often derived from HDM is the Sea Surface Height (SSH). There exists however a very important hidden characteristic with respect to SSH derived from HDM. For instance, the modelled sea level may have a bias relative to a geodetic reference system datum. In many cases, this bias can change both spatially and temporally. This study now examines this bias by comparison of HDM modelled SSH with tide gauges derived SSH that are geodetically referenced to a more stable vertical reference frame such as the marine geoid (equipotential surface of the earth i.e. is the shape of the ocean surface under the influence of the gravity and rotation of Earth alone).</p><p>In this study, the performance of two HDM is analysed for the period 2014‒2015: the Nemo-Nordic (utilised for the Baltic and the North Sea) and the HIROMB-BOOS (used for operational sea forecast in Estonia). In these models, the derived SSH is compared to the fourteen tide gauges (TG) located along the Estonian coastal zone of the Baltic Sea. The vertical reference frame for these tide gauges is fitted to that of a regional high-resolution geoid model, thus deriving the Dynamic Topography. The methodology consisted of: (i) determining the offshore points that are closest to the tide gauge location, (ii) filtering and averaging of the data sets to remove outliers and high-frequency fluctuations (iii) calculation of the SSH bias between TG and HDM (iv) calculation of the standard deviation and root mean square error (RMSE).</p><p>In general, results show that both models conform to a similar trend as tide gauge. The bias however between tide gauge and models varied randomly in magnitude (both spatially and temporally) between both models. The maximum bias for the HIROMB was calculated to be an overestimation of 57 cm and for the Nemo an underestimation of 64 cm. These results hint of possible improvement that can be made in HDM by utilizing a high resolution geoid model that can assist in accurate engineering and scientific studies.</p>

scholarly journals Geomorpho90m - Global high-resolution geomorphometry layers: empirical evaluation and accuracy assessment

2019 ◽  
Author(s):  
Giuseppe Amatulli ◽  
Daniel McInerney ◽  
Tushar Sethi ◽  
Peter Strobl ◽  
Sami Domisch
Keyword(s):  
High Resolution ◽  
Accuracy Assessment ◽  
Empirical Evaluation ◽  
Shuttle Radar Topography Mission ◽  
The United States ◽  
Rate Of Change ◽  
Environmental Models ◽  
Digital Elevation ◽  
The Difference ◽  
Elevation Model

Topographical relief is composed of the vertical and horizontal variations of the Earth's terrain and drives processes in geography, climatology, hydrology, and ecology. Its assessment and characterisation is fundamental for various types of modelling and simulation analyses. In this regard, the Multi-Error-Removed Improved Terrain (MERIT) Digital Elevation Model (DEM) is the best global, high-resolution DEM currently available at a 3 arc-seconds (90 m) resolution. This is an improved product as multiple error components have been corrected from the underlying Shuttle Radar Topography Mission (SRTM3) and ALOS World 3D - 30 m (AW3D30) DEMs. To depict topographical variations worldwide, we developed the Geomorpho90m dataset comprising of different geomorphometry features derived from the MERIT-DEM. The fully standardised geomorphometry variables consist of layers that describe (i) the rate of change using the first and second order derivatives, (ii) the ruggedness, and (iii) the geomorphology landform. To assess how remaining artefacts in the MERIT-DEM could affect the derived topographic variables, we compared our results with the same variables generated using the 3D Elevation Program (3DEP) DEM, which is the highest quality DEM for the United States of America. We compared the two data sources by calculating the first order derivative (i.e., the rate of change through space measured in degrees) of the difference between a MERIT-derived vs. a 3DEP-derived topographic variable. All newly-created topographic variables are readily available at resolutions of 3 and 7.5 arc-seconds under the WGS84 geographic system, and at a spatial resolution of 100 m under the Equi7 projection. The newly-developed Geomorpho90m dataset provides a globally standardised dataset for environmental models and analyses in the field of geography, geology, hydrology, ecology and biogeography.

scholarly journals Accurate Sea Surface heights from Sentinel-3A and Jason-3 retrackers by incorporating High-Resolution Marine Geoid and Hydrodynamic Models

2021 ◽  
Vol 11 (1) ◽  
pp. 58-74
Author(s):  
M. Mostafavi ◽  
N. Delpeche-Ellmann ◽  
A. Ellmann
Keyword(s):  
High Resolution ◽  
Baltic Sea ◽  
Hydrodynamic Model ◽  
Average Distance ◽  
Sea Surface ◽  
Hydrodynamic Models ◽  
Geoid Model ◽  
Sea Surface Heights ◽  
Ice Conditions ◽  
The Baltic

Abstract One of the major challenges of satellite altimetry (SA) is to produce accurate sea surface heights data up to the shoreline, especially in geomorphologically complex sea areas. New advanced re-tracking methods are expected to deliver better results. This study examines the achievable accuracy of Sentinel-3A (S3A) and Jason-3 (JA3) standard retrackers (Ocean and MLE4) with that of improved retrackers adapted for coastal and sea ice conditions (ALES+ SAR for S3A and ALES+ for JA3). The validation of SA data was performed by the integration of tide gauges, hydrodynamic model and high-resolution geoid model. The geoid being a key component that links the vertical reference datum of the SA with other utilized sources. The method is tested in the eastern section of Baltic Sea. The results indicate that on average reliable sea surface height (SSH) data can be obtained 2–3 km from the coastline for S3A (for both Ocean and ALES+SAR) whilst an average distance of 7–10 km for JA3 (MLE4 and ALES+) with a minimum distance of 3–4 km. In terms of accuracy, the RMSE (with respect to a corrected hydrodynamic model) of S3A ALES+ SAR and Ocean retrackers based SSH were 4–5 cm respectively, whereas with the JA3 ALES+ and MLE4 associated SSH RMSE of 6–7 cm can be achieved. The ALES+ and ALES+ SAR retrackers show SSH improvement within a range of 0.5–1 cm compared to the standard retrackers. This assessment showed that the adaptation of localized retrackers for the Baltic Sea (ALES+ and ALES+SAR) produced more valid observation closer to the coast than the standard retrackers and also improved the accuracy of SSH data.

scholarly journals An advanced distributed automated extraction of drainage network model on high-resolution DEM

2014 ◽  
Vol 11 (7) ◽  
pp. 7441-7467 ◽  
Author(s):  
Y. Mao ◽  
A. Ye ◽  
J. Xu ◽  
F. Ma ◽  
X. Deng ◽  
...  
Keyword(s):  
High Resolution ◽  
Network Model ◽  
Land Surface ◽  
Multiple Scales ◽  
Water Cycle ◽  
Computation Time ◽  
Shuttle Radar Topography Mission ◽  
Drainage Network ◽  
Automated Extraction ◽  
Continuous Drainage

Abstract. A high-resolution and high-accuracy drainage network map is a prerequisite for simulating the water cycle in land surface hydrological models. The objective of this study was to develop a new automated extraction of drainage network model, which can get high-precision continuous drainage network on high-resolution DEM (Digital Elevation Model). The high-resolution DEM need too much computer resources to extract drainage network. The conventional GIS method often can not complete to calculate on high-resolution DEM of big basins, because the number of grids is too large. In order to decrease the computation time, an advanced distributed automated extraction of drainage network model (Adam) was proposed in the study. The Adam model has two features: (1) searching upward from outlet of basin instead of sink filling, (2) dividing sub-basins on low-resolution DEM, and then extracting drainage network on sub-basins of high-resolution DEM. The case study used elevation data of the Shuttle Radar Topography Mission (SRTM) at 3 arc-second resolution in Zhujiang River basin, China. The results show Adam model can dramatically reduce the computation time. The extracting drainage network was continuous and more accurate than HydroSHEDS (Hydrological data and maps based on Shuttle Elevation Derivatives at multiple Scales).

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