scholarly journals Evaluating Two Numerical Methods for Developing a Local Geoid Model and a Local Digital Elevation Model for the Red Sea Coast, Egypt

2021 ◽  
Author(s):  
Hamdy M. Ahmed ◽  
Elshewy A. Mohamed ◽  
Shaheen A. Bahaa
Keyword(s):  
Numerical Methods ◽  
Digital Elevation Model ◽  
Red Sea ◽  
Geoid Model ◽  
Digital Elevation ◽  
Red Sea Coast ◽  
Elevation Model ◽  
Local Geoid ◽  
Sea Coast

A method to compute terrain corrections for gravimeter stations using a digital elevation model

Geophysics ◽  
2001 ◽  
Vol 66 (4) ◽  
pp. 1110-1115 ◽  
Author(s):  
J. Garca‐Abdeslem ◽  
B. Martn‐Atienza
Keyword(s):  
Numerical Methods ◽  
Digital Elevation Model ◽  
Mass Density ◽  
Model Solution ◽  
Gravitational Attraction ◽  
Gravity Effect ◽  
Gravity Station ◽  
Digital Elevation ◽  
Terrain Corrections ◽  
Elevation Model

A description is given of a method to compute the terrain corrections for a gravity survey using a digital elevation model. This method is based upon a new forward model solution to compute the gravity effect due to a rectangular prism of uniform mass density that is flat at its base but has a nonflat top. The gravitational attraction of such a prism is evaluated at the gravity station locations by combining analytic and numerical methods of integration. Two simple synthetic examples are provided that show the accuracy of this numerical method, and its performance is illustrated in a field example.

Development and evaluation of the xGEOID20 Digital Elevation Model at NGS

2020 ◽  
Author(s):  
Jordan Krcmaric
Keyword(s):  
Digital Elevation Model ◽  
Geoid Undulation ◽  
Geodetic Survey ◽  
National Geodetic Survey ◽  
Geoid Model ◽  
The North ◽  
Digital Elevation ◽  
Vertical Datum ◽  
Elevation Model ◽  
Ellipsoid Heights

<p>The U.S. National Geodetic Survey (NGS), an office of the National Oceanic and Atmospheric Administration (NOAA), will release a new vertical datum in 2022, the North American-Pacific Geopotential Datum of 2022 (NAPGD2022). This new datum will be based on a high degree spherical harmonic model of the Earth’s gravitational potential, and will yield a geoid undulation model (GEOID2022) to calculate orthometric heights from GNSS-derived ellipsoid heights.</p><p>In preparation for the new vertical datum, NGS has computed annual experimental geoid models (xGEOID) since 2014. This year’s xGEOID model (xGEOID20) will use an updated digital elevation model (DEM) composed of TanDEM-X, 3DEP, MERIT, and other DEMs. The DEMs are merged together to create a seamless elevation model across the extent of the xGEOID20 model. The accuracy of the merged DEM is tested using independent datasets such as GPS on benchmarks and Icesat-2. The effect of the updated DEM on the geoid model is also determined by comparing geoid models computed with previous DEMs to the new xGEOID20 model, and with comparisons to the NGS Geoid Slope Validation Survey lines.</p>

STUDY OF THE LANDSLIDE MORPHOLOGY BASED ON GNSS DATA AND AIRBORNE SOUNDING (ON THE EXAMPLE OF A SECTION OF THE PROTVA RIVER VALLEY)

2018 ◽  
Vol 12 (5-6) ◽  
pp. 50-57 ◽  
Author(s):  
I. S. Voskresensky ◽  
A. A. Suchilin ◽  
L. A. Ushakova ◽  
V. M. Shaforostov ◽  
A. L. Entin ◽  
...  
Keyword(s):  
Digital Elevation Model ◽  
Geodetic Network ◽  
Aerial Survey ◽  
River Valley ◽  
Ease Of Use ◽  
Digital Elevation ◽  
Loose Deposits ◽  
Positioning Method ◽  
Landslide Body ◽  
Elevation Model

To use unmanned aerial vehicles (UAVs) for obtaining digital elevation models (DEM) and digital terrain models (DTM) is currently actively practiced in scientific and practical purposes. This technology has many advantages: efficiency, ease of use, and the possibility of application on relatively small area. This allows us to perform qualitative and quantitative studies of the progress of dangerous relief-forming processes and to assess their consequences quickly. In this paper, we describe the process of obtaining a digital elevation model (DEM) of the relief of the slope located on the bank of the Protva River (Satino training site of the Faculty of Geography, Lomonosov Moscow State University). To obtain the digital elevation model, we created a temporary geodetic network. The coordinates of the points were measured by the satellite positioning method using a highprecision mobile complex. The aerial survey was carried out using an unmanned aerial vehicle from a low altitude (about 40–45 m). The processing of survey materials was performed via automatic photogrammetry (Structure-from-Motion method), and the digital elevation model of the landslide surface on the Protva River valley section was created. Remote sensing was supplemented by studying archival materials of aerial photography, as well as field survey conducted immediately after the landslide. The total amount of research results made it possible to establish the causes and character of the landslide process on the study site. According to the geomorphological conditions of formation, the landslide refers to a variety of landslideslides, which are formed when water is saturated with loose deposits. The landslide body was formed with the "collapse" of the blocks of turf and deluvial loams and their "destruction" as they shifted and accumulated at the foot of the slope.

Roads of Arabia: New finds of Aqaba amphorae in the Red Sea from a newly discovered wreck site at Jeddah/Eliza shoals

2020 ◽  
Author(s):  
Rupert Brandmeier
Keyword(s):  
Saudi Arabia ◽  
Red Sea ◽  
Saudi Arabian ◽  
Maritime Archaeology ◽  
Western Coast ◽  
Research Activities ◽  
Red Sea Coast ◽  
Insight Into ◽  
Sea Coast

This paper concerns a probable shipwreck cargo of Aqaba amphorae, which was discovered during the second season of the survey project along the Saudi Arabian coast, initiated by nautical archaeologists of Philipps-University Marburg and conducted in cooperation with members of the Saudi Commission for Tourism and Heritage in autumn 2013. Seafaring and sea trade was, according to the few ancient sources and modern research activities, a hazardous endeavor in antiquity. Transport containers like the Aqaba Amphorae played a major role in sea trade, a significant number of which have been detected on various sites along the Red Sea coast and its hinterland. The chronological classification as well as the application is far from complete, and recent archaeometrical investigations help to clarify the logistical aspects of manufacturing and distribution of Aqaba amphorae. Finding a number of remains of Aqaba amphorae at a supposed shipwreck site close to Jeddah delivers new insight into the maritime routes and activities along the western coast of Saudi Arabia. The documentary material currently available is the baseline for further research in the field of maritime archaeology as it pertains to trade in the Red Sea.

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