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).