Global Continental Residual Topography

This repository contains estimates of global residual topography after correcting elevation for crustal thickness and density variations. It constitutes the results of Stephenson et al. (2024). A full methodological description can be found in that paper. 'Residual topography' is topography supported by mantle buoyancy structure after having crustal isostatic topography removed. The crustal thickness database used to calculate these reisudal topographic estimates is SeisCruST, a global seismic crustal thickness and structure database. Crustal density calculations are carried out using SMV2rho, a package designed to estimate cotinental crustal density from seismic velocity profiles.

NOTE

Crustal thickness estimates are taken from a large database of estimates of crustal thickness and velocity determined by a variety of seismic experiments. If using the crustal thickness, velocity or density information provided here, it is imperative that the user refer to the documentation in SeisCruST and properly reference both that package and the individual authors whose work is included in the compilation.

Binned residual topographic estimates

The BINNED_RESIDUAL_ELEVATION/ directory contains data where the residual topography has been averaged into bins of 1, 2, 3, and 4 degrees.

The data is organized into the following columns:

| Column Name | Description | | --- | --- | | lon | Longitude | | lat | Latitude | | t_c | Depth of the Mohorovičić discontinuity (the boundary between the Earth's crust and mantle) | | residual_elevation | Residual elevation | | residual_elevation_error | Error in the residual elevation |

Pointwise residual topographic estimates

The POINTWISE_RESIDUAL_ELEVATION/ directory contains station-by-station residual topgoraphic estimates with uncertainties. IIt also contains geophysical parameters exracted locally to the station from global grids. The structure is as follows:

| Column Name | Description | | --- | --- | | station | The identifier for the station where the data was collected (NaN if no velocity profile present). | | lon | Longitude of the station. | | lat | Latitude of the station. | | t_c | Depth to Moho. | | vp | Bulk P-wave velocity. | | vs | Bulk S-wave velocity. | | rho_c | Density of the crust calculated using temperature dependent version of SMV2rho. | | ETOPO | Topographic elevation. | | ETOPO_filt_30km | Topographic elevation filtered for wavelengths > 30 km. | | tl | Lithospheric thickness taken from Hoggard et al. (2021) at the station. | | long_lam_grav | Long-wavelength free air gravity anomaly at the station. | | thickness_correction | Crustal thickness correction | | density_correction | Crustal density correction | | residual_topography | Residual topographic estimate | | dens_err_all | Crustal density error | | res_topo_err | Residual topography error | | dens_corr_err | Crustal density correction error | | thickness_corr_err | Crustal thickness correction error |

Input crustal files

Located in INPUT_CRUST_FILES/. Here the input crustal thickness and density data can be found, as well as several other geophysical parameters extracted locally from various grids at the site of each data point.

Crustal database

This data file station_lon_lat_vp_vs_rho_topo_filt_lith_grav_all_onshore.dat contains pointwise crustal thickness, velocity and density estimates as well as geophysical parameters extracted locally from various grids at each data point. Velocity and density is taken from SeisCruST and SMV2rho. Please refer to documentation for these packages for more information. The columns in the file are described as follows:

| Column Name | Description | | --- | --- | | station | The identifier for the station where the data was collected (NaN if no velocity profile present). | | lon | Longitude of the station. | | lat | Latitude of the station. | | t_c | Depth to Moho. | | vp | Bulk P-wave velocity. | | vs | Bulk S-wave velocity. | | rho_c | Density of the crust calculated using temperature dependent version of SMV2rho. | | ETOPO | Topographic elevation. | | ETOPO_filt_30km | Topographic elevation filtered for wavelengths > 30 km. | | tl | Lithospheric thickness taken from Hoggard et al. (2021) at the station. | | long_lam_grav | Long-wavelength free air gravity anomaly at the station. |

Sea level reference model

sea_level_points.dat contains the subset of points within 25 m of sea level.

Scripts

The SCRIPTS/ directory contains useful processing and plotting routines.

Residual topography calculation notebook

calc_residual_topography_crust_only.ipynb contains a notebook to calculate continental residual topography. It also contains some useful plots and processing to remove outliers that are fully described in Stephenson et al. (2024).

Residual topography binning

bin_residual_topography.gmt contains a shell or gmt script to average residual topography into $1\times1$ degree bins and then calculate some useful statistics on the binned results.

Excision polygons

excision_polys_combined.ll contains polygons to mask out parts of the world where flexure or orogenesis may be a significant control on topography.

License

The package is distributed under an MIT license.