Setting up: the Launcher and the Builder
The Launcher
| Preset | A design included with the app. |
| Import | A design pasted as JSON in the Export tab’s format. |
| Blank | The default design of the model chosen in the Model dropdown. |
Choosing a model
A preset or file names its model, a file in model.type as "primitive" or "quasigeostrophic", and the Launcher opens that model’s card. Choosing the other model under Blank returns every control to its defaults and clears the chosen preset.
The presets
Without an HTTP server the list is empty. A pick turns the card at once, and the stage reads Loading and the preset’s name until its preview can be drawn.
| Preset | Design |
|---|---|
| Our Earth | Full Primitive. The Earth’s coastlines, relief, deserts and land ice, sixteen levels at 256 × 128, moist, with the sea Dynamic and the sea ice the observed 1991–2020 climatology. A state at day 457. |
| Another Earth | Full Primitive. As Our Earth, over painted continents, its sea on the idealised law and its sea ice Dynamic. A state at day 561. |
| Held–Suarez | Full Primitive. The dry benchmark without land, sixteen levels at 128 × 64. |
| Hemispheric Earth | Quasi-Geostrophic. A moist, forced hemispheric cap of eight layers, the top two a stratosphere, with sea ice and land. A state at day 2,763. |
| Stripe Earth | Quasi-Geostrophic. A dry, forced, four-layer channel from 10° to 80° N, four times as wide as high. |
| Simple Box | Quasi-Geostrophic. The unforced two-layer periodic plane, a β-plane at 45° N, with a 350 km deformation radius and a 35 m/s jet. |
The tickboxes
Each optional block of a preset or file has a tickbox.
- Include land or Import land is held ticked while the snapshot box is, and unticked leaves the design over open ocean.
- Start with preset’s view settings or Import view settings, unticked, keeps the default look.
- Start from snapshot or Import snapshot, unticked, starts the design from a fresh seed.
Next and Initialize
Next leads to the Builder. With the snapshot box ticked, a Full Primitive or hemispheric Quasi-Geostrophic design bypasses the design steps for the Compute card, and on a flat Quasi-Geostrophic design the button reads Initialize and starts the run. A run launched from the snapshot keeps the snapshot’s grid and clock, and Reset Simulation returns to it.
On a large design the stage names each wait: while a stored state is read, while Next prepares the Builder’s preview of a Full Primitive design that the Launcher’s preview does not already show, and while the run starts. The stage moves once the preview can be drawn, the button is inactive meanwhile, and the window does not respond while the work runs.
Importing a file
A paste replaces the box’s text. The stage reads Loading JSON… until the preview can be drawn, and the card then turns to it; the button is inactive meanwhile. A file or state the model cannot take is refused. A pasted design is discarded when another source or model is chosen.
The Builder
Every Full Primitive design and a hemispheric Quasi-Geostrophic one have a third step, Compute.
The domain (step 1)
Full Primitive
| Control | Effect |
|---|---|
| Resolution | From 64 × 32 to 512 × 256 cells. Each position quadruples the cells and halves the derived time step, so a model day costs about eight times the computation of the position below. At 512 × 256 with sixteen levels the page holds about 2.2 GB, and the diffusion times apply at half their stated values. |
| Transition | The η below which interfaces are pressure surfaces. |
| Exponent | Lowering it or the Transition permits taller mountains. |
| Regenerate initial state | Re-seeds the perturbation at the next zonal wavenumber. |
Quasi-Geostrophic
Periodic is a doubly periodic β-plane about the Central latitude, and Hemisphere a polar cap of fixed size whose near-equatorial flow is a boundary condition. Channel, zonally periodic between free-slip walls, alone offers Coriolis.
- f-plane holds f uniform at the Central latitude.
- β-plane varies f linearly about that latitude.
- Earth-like takes the real variation between Lower latitude and Upper latitude, whose separation sets the domain’s height at 111 km per degree. Domain width, a multiple of that height, replaces Domain size and Central latitude.
| Control | Effect |
|---|---|
| Domain size | Side of a periodic domain, or width of a channel, which is half as high. |
| Treatment | Earth-like channel or hemisphere only. Under Latitude-dependent (c/f) the radius slider states the radius at the band’s midpoint, 45° N on the hemisphere, and Saturate toward the equatorial radius stops it diverging near the equator. |
| Resolution | Cells per deformation radius. Fewer than 2 suppresses the eddies, and 4–8 resolves them. A latitude-dependent radius must be resolved at its smallest. |
| Initial mean zonal jet | On the hemisphere, an annular westerly at 45° N. |
| Regenerate initial state | Moves the precursor of the first storm. |
The vertical column (step 2)
Full Primitive
The reference column falls from the Surface temperature at the Lapse rate to the Stratosphere temperature at the tropopause, uniform above, and the column diagram names the tropopause in amber on its axis with its height and pressure. With the thermal forcing Off the run starts from this column at rest, and with it On from the forcing’s seed.
Quasi-Geostrophic
The troposphere spans 10 km, and the surface slab is at least 1,457 m (850 hPa) thick.
| Control | Effect |
|---|---|
| Troposphere layers | At most eight in all, stratosphere included. |
| Density | Earth-like lets it fall as exp(−z/H), with H the Density scale height, and offers Layer thickness. |
| Layer thickness | Mass-weighted gives the tropospheric slabs equal mass, so they thicken with height. |
| Stratosphere | On adds two 5 km slabs above the tropopause, unheated by the forcings, and offers Stratosphere stiffness, their resistance to vertical motion relative to the troposphere. |
The Compute card (step 3)
A design launched from a stored state stops here, with Setup its only retreat. Each model’s card keeps its own choice, which applies at Initialize.
| Control | Effect |
|---|---|
| Kernel execution | Multi-core requires cross-origin isolation, which a page opened from file:// lacks. |
| CPU cores | The threads the run steps on, from 2 to 16. A mark, Browser-reported max, stands at the number of logical processors the browser reports for the machine, hyper-threads included, and a warning appears beneath the slider while more threads than that are chosen; a browser may report fewer processors than the machine has. The default is the reported count less two, at most 8. |
What the design keeps
Initialize fixes the Builder’s settings for the run. A saved design carries the first two steps’ controls, except Regenerate initial state and Domain size.
Leaving the Builder
| Setup | Returns to the Launcher, keeping Builder edits for a Blank design only. |
| Back to Builder | Discards the run, its parameter changes and Terrain painting, restoring the design as launched. Only an export made beforehand keeps painted coastlines. |
| Back to Launcher | Replaces Back to Builder after a launch from a stored state, keeping nothing of the run. |
Each restores the default view mode, pointer tool and display settings, or the source’s look where its view box is ticked.