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).
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).
The model named EHFM_Earth_7200 was derived by layer-based forward modeling technique in ellipsoidal harmonics, the maximum degree of this model reaches 7200. The relief information was provided by Earth2014 relief model. EHFM_Earth_7200 provides very detailed (~3 km) information for the Earth’s short-scale gravity field, and it is expected to be able to augment or refine existing global gravity models. To meet the existing standard, here we provide spherical harmonic coefficients, which are transformed from original ellipsoidal harmonic coefficients. The maximum degree of the spherical harmonic coefficients is 7300.