API src

Found 5 results.

Other language confidence: 0.9882414822396386

Rock-Water-Ice topographic gravity field model 2015 (RWI 2015 model)

High-resolution spherical harmonic representation of the Earth's topographic gravitational potential based on a three-layer decomposition of the topography with variable density values. Main features: - Three-layer decomposition of the topography using information of the new 1'x1' Earth2014 topography model - Rigorous separate modeling of rock, water, and ice masses with layer-specific density values: Rock: 2670 kg m-3, Water: 1030 kg m-3 (Ocean), 1000 kg m-3 (Inland), Ice: 917 kg m-3 - Ellipsoidal arrangement of the topography using the GRS80 ellipsoid + geoid undulations as height reference surface - Additional compilation of a consistent rock-equivalent version REQ_TOPO_2015 using condensed DTM-heights Processing: - Forward modelling in the space domain using tesseroid mass bodies - Transformation of global gridded values to the frequency domain by applying harmonic analysis up to degree and order 2190 Model versions: - Spherical harmonic coefficients of the RWI model are provided by two versions (GM = 3.986004415e+14 m3 s-2, a = 6378136.3 m): RWI_TOPO_2015 (topographic potential) REQ_TOPO_2015 (topogr. potential of rock-equivalent heights) - To allow the evaluation of the RWI model by synthesis software that by default subtracts the coefficients of a normal gravity field, two additional versions are available: RWI_TOPO_2015_plusGRS80 (RWI_TOPO_2015 + GRS80) REQ_TOPO_2015_plusGRS80 (REQ_TOPO_2015 + GRS80) where the following zonal harmonic coefficients of the GRS80 normal gravity field are added to the coefficients of the RWI model: C( 0,0) = 0.100000014676351e+01 C( 2,0) = -0.484167032228604e-03 C( 4,0) = 0.790304535833168e-06 C( 6,0) = -0.168725253450154e-08 C( 8,0) = 0.346053594536695e-11 C(10,0) = -0.265006548323563e-14 C(12,0) = -0.410788602320538e-16 C(14,0) = 0.447176931400485e-18 C(16,0) = -0.346362561442980e-20 Note that these coefficients are already rescaled to the above specified parameters GM and a of the RWI model. Details about the used Earth2014 topography model can be found in Hirt and Rexer (2015, https://doi.org/10.1016/j.jag.2015.03.001).

PRESSurE precipitation time series, Nepal

This data set was taken within the Perturbations of Earth Surface Processes by Large Earthquakes PRESSurE Project (https://www.gfz-potsdam.de/en/section/geomorphology/projects/pressure/) of the GFZ Potsdam. This project aims to better understand the role of earthquakes on earth surface processes. Strong earthquakes cause transient perturbations of the near Earth’s surface system. These include the widespread landsliding and subsequent mass movement and the loading of rivers with sediments. In addition, rock mass is shattered during the event, forming cracks that affect rock strength and hydrological conductivity. Often overlooked in the immediate aftermath of an earthquake, these perturbations can represent a major part of the overall disaster with an impact that can last for years before restoring to background conditions. Thus, the relaxation phase is part of the seismically induced change by an earthquake and needs to be monitored in order to understand the full impact of earthquakes on the Earth system. Early June 2015, shortly after the April 2015 Mw7.9 Gorkha earthquake, 6 automatic compact weather station were installed in the upper Bhotekoshi catchment covering an area ~50km2. The weather station network is centered around the Kahule Khola catchment, a small headwater catchment and is part of a wider data acquisition strategy including hydrological monitoring, seismometers, geophones and high resolution optical (RapidEye) as well as radar imagery (TanDEM TerraSAR-X). https://www.gfz-potsdam.de/sektion/geomorphologie/projekte/pressure/

Rock-Water-Ice topographic-isostatic gravity field model 2012 (RWI 2012 model)

High-resolution spherical harmonic representation of the Earth's topographic, isostatic, and topographic-isostatic gravitational potential based on a three-layer decomposition of the topography with variable density values and a modified Airy-Heiskanen concept incorporating seismic Moho depths. Main features: - Three-layer decomposition of the topography using information of the 5'x5'global topographic database DTM2006.0 - Rigorous separate modeling of rock, water, and ice masses with layer-specific density values (2670, 1000, 920 kg m-3) - Avoidance of geometry changes compared to classical condensation methods (e.g. rock-equivalent heights) - Ellipsoidal arrangement of the topography using the GRS80 ellipsoid as reference surface - Adapted and modified Airy-Heiskanen isostatic concept - Incorporation of seismic Moho depths derived from CRUST2.0 - Location-dependent estimation of the crust-mantle density contrast Processing: - Forward modelling in the space domain using tesseroid mass bodies - Transformation of global gridded values to the frequency domain by applying harmonic analysis up to degree and order 1800 Model versions: - Spherical harmonic coefficients of the RWI model are provided by three versions (GM = 3.986004415e+14 m3 s-2, a = 6378136.3 m): RWI_TOPO_2012 (topographic potential) RWI_ISOS_2012 (isosatic potential) RWI_TOIS_2012 (topographic-isostatic potential) - To allow the evaluation of the RWI model by synthesis software that by default subtracts the coefficients of a normal gravity field, three additional versions are available: RWI_TOPO_2012_plusGRS80 (topographic potential + GRS80) RWI_ISOS_2012_plusGRS80 (isosatic potential + GRS80) RWI_TOIS_2012_plusGRS80 (topogr.-isostatic potential + GRS80) where the following zonal harmonic coefficients of the GRS80 normal gravity field are added to the coefficients of the RWI model: C( 0,0) = 0.100000014676351e+01 C( 2,0) = -0.484167032228604e-03 C( 4,0) = 0.790304535833168e-06 C( 6,0) = -0.168725253450154e-08 C( 8,0) = 0.346053594536695e-11 C(10,0) = -0.265006548323563e-14 C(12,0) = -0.410788602320538e-16 C(14,0) = 0.447176931400485e-18 C(16,0) = -0.346362561442980e-20 Note that these coefficients are already rescaled to the above specified parameters GM and a of the RWI model. Details about the used DTM2006.0 topography model can be found in Pavlis et al. (2012, https://doi.org/10.1029/2011JB008916). Details about the used CRUST2.0 model is available from Laske et al. (2000, https://igppweb.ucsd.edu/~gabi/crust2.html).

Rock-Ocean-Lake-Ice topographic gravity field model (ROLI model) expanded up to degree 3660

The determination of the global gravity field has gained momentum due to high accuracy satellite-derived observations and development of forward gravity modelling. Forward modelling computes the global gravitational field from mass distribution sources instead of actual gravity measurements and helps improving and complementing the medium to high frequency components of the global gravity field models. In this study, we approximate the global gravity potential of the Earth’s upper crust based on ellipsoidal approximation and a mass layer concept. Lateral density variations within a sequence of thin volumetric shells bounded by confocal lower and upper shell ellipsoids are used in the computation of the ellipsoidal harmonic coefficients which are then transformed into spherical harmonic coefficients on the Earth’s surface in the final step. The main outcome of this research is a spectral representation of the Earth’s upper crust’s gravitational potential, computed up to degree and order 3660 in terms spherical harmonic coefficients (ROLI_EllApprox_SphN_3660).

GDEMM2024: 30 Arcsec Global Digital Elevation Merged Model 2024, a suite for Earth relief

We merged various digital elevation models (DEMs) published in the recent years and created an up-to-date composite and global solution for Earth’s topography and bathymetry. Compared to the original geographically limited data sets, the final product is a seamless merged grid which additionally provides high resolution and accuracy topography and depth globally. We provide Earth relief grids w.r.t EIGEN-6C4 global geoid in terms of surface and bedrock elevation, ice thickness, and land-type masks which have been substantially improved w.r.t the global grids found in literature. We assessed the quality of the merged surface elevations w.r.t the heights given for about globally distributed 5000 ITRF stations. The merged surface model shows improvement of a factor of three w.r.t the other commonly used DEMs in terms of standard deviation. In addition to the four grids, GDEMM2024_SUR, GDEMM2024_BED, GDEMM2024_ICE, and GDEMM2024_LTM, we provide two additional files, the surface elevation without water (GDEMM2024_TBI) and the GDEMM2024_GEO file to transform the heights above EIGEN_6C4 geoid to ellipsoidal heights. The final grids are provided both in 30 arcsec and 1arcmin resolution and in GeoTIFF format which is one of the standards that is available in GMT (Generic Mapping Tools), GDAL (Geospatial Data Abstraction Library) and in almost all GIS software systems.

1