Output variables & visualisation#

goSPL writes its results to the directory given by the output: dir key of the input file. Each output interval (time: tout) produces, per MPI rank, an HDF5 data file plus a small XDMF descriptor; a top-level .xmf / .xdmf file ties the per-step, per-rank pieces together. Open the top-level ``gospl.xdmf`` in ParaView (or any XDMF reader) — it exposes every surface field below as a node-centred scalar that can be coloured, warped and filtered.

This page lists the fields goSPL can write and what they mean, then shows how to turn the flat-mesh or global-sphere output into a 3-D surface in ParaView.

Output fields#

Many fields are only written when the corresponding process is enabled (noted in the When written column). Unless stated otherwise, lengths are in metres and rates are per year; discharges/fluxes are volumetric (m³/yr).

Core surface#

Field	Meaning	When written
`elev`	Surface elevation of the bed.	always
`erodep`	Cumulative erosion (negative) and deposition (positive) since the start of the run.	always
`EDrate`	Erosion–deposition rate over the current step (m/yr; negative = incision).	always

Water & drainage#

Field	Meaning	When written
`FA`	Water flow accumulation (drainage discharge, m³/yr) on the actual surface.	always
`fillFA`	Flow accumulation on the depression-filled surface — drainage routed through lakes/pits.	always
`waterFill`	Filled water-surface elevation (lake / depression water level).	when depressions are filled
`sedLoad`	River sediment load carried downstream (m³/yr).	always
`sedLoadF`	Fine-fraction sediment load/flux (dual-lithology runs only); coarse flux = `sedLoad − sedLoadF`.	dual lithology
`surfFineFrac`	Surface exposed fine fraction (mud share, 0–1, of the topmost stratigraphic layer) — the in-place composition, complementing the `sedLoadF` flux.	dual lithology
`rain`	Precipitation rate forcing the run (m/yr).	when rainfall is set
`evap`	Evaporation rate (m/yr).	when evaporation is set

Soil, tectonics & flexure#

Field	Meaning	When written
`soilH`	Soil / regolith thickness.	`soil` enabled
`uplift`	Vertical tectonic displacement rate applied this step (m/yr; positive = uplift).	vertical tectonics
`flexIso`	Flexural isostatic vertical deflection (m; positive = up).	`flexure` enabled

Glacial (ice) fields#

Written only when an ice section is present (see Surface processes parameters). The diagnostic glacial model derives these each step from the routed ELA accumulation — there is no ice-thickness time integration.

Field	Meaning	Units
`iceH`	Ice thickness from the Bahr discharge scaling \(H=\mathrm{eheight}\cdot\mathrm{fwidth}\cdot Q^{0.3}\). Zero below the terminus.	m
`iceFA`	Ice discharge \(Q\) — the volume of ice routed through each cell (the glacial analogue of river `FA`).	m³/yr
`iceUb`	Basal sliding velocity magnitude from Glen’s sliding law on the ice thickness and bed slope (\(u_b\propto H^{n-1}\|\nabla s\|^{n-1}\nabla s\)). This is the driver of abrasion.	m/yr
`iceAbr`	Glacial (vertical) abrasion rate \(E_g = K_g\,\|u_b\|^{l}\) — bed lowering by sliding ice. (Lateral valley-wall erosion, `Kl`, contributes to bed change via the till budget but is not added into this field.)	m/yr
`iceMelt`	Glacial meltwater delivered to the rivers — the ice accumulation released as liquid water where the ice melts out (ablation zone / terminus). With `melt_conserve: True` it is discharge-conserving (total melt = total accumulation), so it shows where glaciers feed streamflow. Not the same as the internal till-deposition weight.	m³/yr

Note

To see glacial valley deepening, colour by erodep / EDrate (the bed change) — iceAbr reports only the vertical abrasion rate. To see valley widening (U-shaping), enable lateral wall erosion with abrasion: Kl > 0 (see Surface processes parameters) and inspect erodep across the valley: vertical Kg deepens the trough, lateral Kl lowers the flanking walls. Increasing Kg deepens more but does not widen — widening is controlled by Kl.

Stratigraphy#

Written when stratigraphic recording is on (strat interval set), in the separate h5/stratal.<step>.p<rank>.h5 files. These are per-layer arrays (one column per recorded layer): stratZ (layer elevation), stratH (layer thickness), phiS (porosity), stratK (erodibility multiplier), stratP (per-layer provenance), and, under dual lithology, stratHf (fine-fraction thickness) and phiF (fine porosity). The per-layer fine fraction is stratHf / stratH.

The stratal HDF5 files have no XDMF wrapper of their own. Several post-processing tools turn them into figures (all documented, with the exact commands, in Running goSPL):

3-D volume for ParaView — gospl-strata-volume stacks the layers into a wedge (triangular-prism) volume coloured by lithology or provenance.
Publication sections / wells / Wheeler diagrams — gospl-section draws vector cross-sections (along x/y/a path), horizontal depth slices, synthetic wells (one, or several side by side via well_panel) and chronostratigraphic (Wheeler) charts, coloured by deposition elevation, thickness, lithology, porosity, age, provenance or depositional facies (water depth at deposition). Distance is shown in km, time in ky; see Running goSPL for the full option list.
Surface composition over time — instead of the pile, colour the main gospl.xdmf by surfFineFrac (in-place mud share) or sedLoadF (fine transport flux).

Visualising in ParaView#

The mesh is stored flat — node coordinates plus the elev (Z) scalar — so by default ParaView shows a flat sheet (planar model) or a smooth sphere (global model) coloured by whatever field you pick. Apply one of the filters below to turn elevation into relief.

Flat / planar model — Warp By Scalar#

Load the .xdmf and colour by a field (e.g. elev).
Apply Filters → Alphabetical → Warp By Scalar.
Set Scalars = Z (the elevation), choose a Scale Factor (1 for true scale, larger for vertical exaggeration), and Apply.

The sheet now stands up as topography; re-colour by erodep, FA, iceH, … as needed.

Global / spherical model — Calculator radial warp#

For a global run the nodes already lie on a sphere of radius ~6 378 137 m, so a Warp By Scalar would displace them incorrectly. Instead push each node radially by its (exaggerated) elevation with a Calculator filter:

Apply Filters → Alphabetical → Calculator.
Tick Coordinate Results and Result Normals.
Set the expression to:
```
(iHat*coordsX + jHat*coordsY + kHat*coordsZ) * (1 + Z*50/6378137)
```
Here coordsX/Y/Z are the node coordinates, Z is the elevation scalar, and 50 is the vertical-exaggeration factor (raise/lower to taste; 1 gives true scale). The term 1 + Z·50/6378137 scales the radius by the (exaggerated) elevation as a fraction of the planet radius.
Apply, then in the Properties set the Interpolation to Flat (rather than Gouraud) so faceted relief reads clearly.

Note

6378137 is Earth’s radius in metres — goSPL’s default. If you are modelling another planet, set the planet radius (and surface gravity, used by the flexural-isostasy solver) in the domain block of the input file and substitute that radius into the formula above. For example, a Mars run (radius ≈ 3 389 500 m, gravity ≈ 3.71 m/s²):

domain:
    npdata: ['input/mesh', 'v', 'c', 'z']   # spherical mesh: vertices, cells, elevation
    radius: 3389500.0                       # planet radius (m); default 6378137 (Earth)
    gravity: 3.71                           # surface gravity (m/s^2); default 9.81 (Earth)
    flowdir: 6                              # MFD flow directions

would use ... * (1 + Z*50/3389500) in the Calculator. (The bc edge key is for flat/planar meshes only — a spherical planet mesh has no edges.)

Re-colour the warped surface by any output field to inspect topography, drainage, ice or sediment in 3-D.

Gridded export for PyGMT / ArcGIS (basins, χ, river profiles)#

goSPL’s native output is an unstructured triangular mesh, which PyGMT and ArcGIS do not read directly. The gospl-grid tool reassembles the global mesh, interpolates every surface field of a step onto a regular CF-NetCDF grid (lon/lat for global meshes), and runs a raster D8 hydrology pass to add drainage_area, basin and chi (\(\chi\)); a companion notebook API extracts per-basin river longitudinal profiles. The base level for catchments/χ defaults to the run’s sea level. See Running goSPL for the command, options and the river-profile API.