Adamastor

The map in Watch

Under Watch a drag pans the map or turns the Orthographic globe, and a double-click resets the view. The pivot, a right-button drag or a drag with Option or Alt held, turns a polar map about the pole and scrolls the longitude at which a Winkel Tripel map is cut. The Full Primitive sphere offers Winkel Tripel, Orthographic, Polar N and Polar S, the last seen from outside the globe with east clockwise, and a Quasi-Geostrophic hemisphere Polar, Winkel Tripel and Orthographic. Each projection keeps its own zoom, position and rotation.

A stationary click pins a point and opens the Sample window, which reports conditions there, with running means under Climatology. On the plane and the channel, positions are kilometres east and north of the lower-left corner. Closing the window clears the pin.

Under Full Primitive the levels follow the ground, so no level lies inside a mountain. Under Quasi-Geostrophic a layer shows nothing over a mountain that fills it, and the Sample window reads a dash there for the layer’s quantities. The layer holding the crest, and the fields without a layer, are drawn over the mountain. Beside the rock the surface wind is slower than the surrounding flow.

The display dock writes the same state as View Settings. Its right end carries the View Settings button, the header’s twin, and the chevron that collapses the dock to that end. With the Layers column’s Sync tick on, one Layer column steps every synced surface. Under Full Primitive a stepper shows its level’s index and its column’s label the level’s pressure in millibars; with the layers synced the Layer column shows both on its stepper, as do the Layer rows of the Air over Ocean and Air over Land cards. Beneath the lowest level a stepper reaches the Surface position where its field has one, which it shows as S, with SFC in place of the pressure; the Centres column reaches it too, where the centres lie on the sea-level or surface pressure. The Land column’s Show tick sets the Land view mode to Invisible or back to the last visible mode.

The fields

The Climatology fields are running means over the session. A mean wind speed is the mean of the speed, not the speed of the mean wind.

Full Primitive

The Geopotential height is the height of the level’s pressure surface, and the Level height follows the ground. The boundary-layer, sea, moisture and sea-ice fields are described under their cards.

While the boundary layer runs, Temperature, Potential temperature, Specific humidity, Relative humidity, Zonal wind, Meridional wind and Wind speed each have a Surface position beneath the lowest level, named Surface in the layer menus and S on the dock’s steppers, with SFC in place of the pressure. It holds the temperatures and humidities 2 m above the ground and the winds 10 m above it, read from the surface layer’s profile between the ground and the lowest level, under the field’s own colour map, range and isoline interval. There the tracers and the wind arrows follow the 10 m wind, and the Sample window quotes the screen-level values. The 2 m relative humidity is not capped and exceeds 100 % at night over land, where the ground cools below the dew point of the air above, and over open water beneath much colder air. With the boundary layer off the position is withdrawn, and a field on it moves to the lowest level.

The Geopotential height has a Surface position too, the Mean sea-level pressure, offered whatever the boundary layer: a layer selector moved to S with the height chosen lands on it, and a step upward returns to the height. A quantity of its own, it keeps its name and place in the class menus, where its layer menu reads Surface with the height’s levels beneath, and its own colour map, range and 4 hPa interval.

The map opens on the lowest level’s temperature, contoured by the geopotential height of the level nearest 500 hPa. The geopotential height’s chart interval, held per level, is 30 m at 600 hPa and below, 60 m to 350 hPa and 120 m above, and at the lowest level matches the 4 hPa spacing of the sea-level isobars.

Quasi-Geostrophic

Vertical motion is positive for ascent and zero until the first step. The Temperature anomaly lies on the interfaces between layers. Pressure and Temperature are their anomalies plus a standard-atmosphere background at each layer’s own height, the surface layer’s at 10 m. Column water (per cent of the reference saturation), precipitation (per cent of that column per day), cloud cover and mountain blocking have no layer, and the first three read zero while the Moisture card is off.

The map opens on the wind speed in the highest tropospheric layer, contoured by the surface layer’s Pressure every 4 hPa.

View Settings

General

Shading

Contours

Contours 1 and Contours 2 are two independent isoline sets.

Shape

The shape is an optional base field in the Mono ramp beneath the shading, and Blend sets the shading’s opacity over it. Under Full Primitive, precipitation, cloud amount and their means add a Floor, independent of the shading’s, at which the ramp begins, black below it.

Crosshatching

A fourth field slot hatches every region where its field exceeds the Threshold. Each field keeps its own threshold and style. Precipitation has two style cards under one threshold, Rain where the surface is above freezing and Snow below, and its mean a single one.

Tracers

Tracers are wind-borne particles whose brightness follows speed. Their Layer follows the shaded layer until set. Unticked, True wind speed moves them at a fixed pace that Scaling with wind intensity multiplies, as it does the brightness. Ticked, while the run plays, the same streaks, with the same trail length, density and brightness, move at the local wind in model time: their motion, their fading and their renewal run at the rate the model clock advances. Paused, they return to the fixed pace. Density multiplies the standard particle density, up to Density ceiling. Trail length is the time constant of the trails’ fade. Dim field under tracers darkens the shading by Dim strength and draws the streaks at Streak strength. The tracers flow whether the run plays or pauses. Under the Terrain tool they are hidden and their switch disabled. Under a reduced-motion preference they hold still as short streamlets.

Overlays

Pressure centres mark highs and lows on the layer or level of Centres from, whatever the map shades.

Full Primitive. Centres from offers Surface beneath the levels. There Pressure at, shown at that position alone, chooses the sea-level pressure or the Surface pressure, on which alone a mountain appears as a low. At every level, the lowest included, the centres lie on the geopotential height of the level’s pressure surface, labelled in metres.

Quasi-Geostrophic. The centres lie on the layer’s pressure, labelled by Values as the absolute Pressure or the signed Anomaly.

While Full Primitive’s Diurnal Cycle pill is On, these overlays are drawn:

The Statistics window

The Statistics window shows the clock and step count, the global diagnostics, each level’s or layer’s Peak wind and Vort RMS, and a sparkline of the peak wind.

Full Primitive. Temperature spread is the RMS departure of temperature from each level’s area mean, over all levels. The drift of Mean surface pressure is the mass budget. Polar surface pressure averages the two polar rings. Jet strength is the strongest zonal-mean zonal wind at the level nearest 250 hPa, and Jet latitude its latitude, north positive.

Quasi-Geostrophic. Painted cells sums the cells of every Interact patch dropped. Temperature RMS is the RMS temperature anomaly over all interfaces. With Moisture on, the area-mean Column water, Evaporation, Precipitation and Water balance (E − P, the trend in stored water) follow.

The control panel

During a run the control panel’s tabs hold these cards.

The System tab

The System card describes the running design.

The Atmosphere card shows the vertical column, fixed for the run, above a cartoon. A cartoon box’s sync button sends every layer choice to its level or layer, whether or not Sync layer choice is ticked.

Full Primitive

Levels gives the transition η_t of the hybrid σ–p coordinate. Levels are named by their reference pressure.

Quasi-Geostrophic

Vertical column appears only with a stratosphere or Earth-like density.

The Simulation tab

Every control here acts from the next step without reseeding. Builder values change only through Back to Builder, which discards the run.

Simulation. The logarithmic Time step slider carries an optimal mark that follows the flow. Pin to optimal holds the step at the mark and disables the slider. Restrict by optimal caps the step there, and the two exclude each other. Steps per frame changes the pacing, not the result.

Friction. On the Quasi-Geostrophic card Land drag applies over land and desert, and a mountain of height h takes the fraction 1 − exp(−h/1 km) of the way from it to the Mountain drag. A drag of 0 over land takes the sea’s rate. The Full Primitive card sets one drag per surface type.

Moisture. On the Quasi-Geostrophic card Land uptake scales the evaporation of land and mountain cells against the ocean’s, and desert never evaporates. The Full Primitive card sets one uptake per land type. Under Off, which disables the card’s settings, every moisture field reads zero except the Full Primitive infrared cloud cover.

Full Primitive

Every slider on the Friction, Boundary Layer, Ocean, Moisture and Sea Ice cards, and on the Forcing tab’s Base Atmosphere, Air over Ocean and Air over Land cards, carries an Earth-like mark at its default; a click on the mark returns the slider there. A blank design stands at every mark.

Simulation

The optimal mark is the least of one hour and the three limits beneath the slider, and the stage warns above 1.8 times it. A design the kernel refuses is not run. The Diffusion time acts on the shortest retained wave, and on the divergence unless Separate divergence time is ticked. On the 512 × 256 grid both times apply at half their stated values, which keeps the damping per step that of 256 × 128. A time too short for the step is lengthened. The sponge damps the winds above the Sponge base, reaching its Damping time at the top.

Friction

The card sets the Rayleigh friction as one rate at the ground per surface type, whatever the thermal forcing and the cell’s height; sea ice takes the Ocean drag, and a land type’s drag of 0 takes it too. The friction falls linearly with pressure to zero at the Boundary-layer top σ_b (0.70 by default), a fraction of the ground’s pressure that also sets the boundary layer of the relaxation. The plot draws the five rates against the height above the ground, the levels’ interfaces marked.

Boundary Layer

The card sets the surface fluxes of heat and moisture and their turbulent mixing (Frierson, Held and Zurita-Gotor 2006), whatever the thermal forcing. The heat flux acts over open sea at the Ocean card’s temperature, and over land as the Air over Land card’s diurnal heating while the Diurnal Cycle is On. Over land the ground stands at the lowest level’s air brought down the dry adiabat, with its diurnal swing, and over land ice and sea ice no warmer than 0 °C.

It adds Sensible heat flux (W/m², positive upward) and Boundary-layer height (m) to the pickers, and the screen-level fields at the Surface position.

After the boundary layer, every step mixes each layer whose potential temperature falls with height to neutral, keeping the column’s heat (a dry convective adjustment, Manabe and Strickler 1964), with the scheme on or off.

Ocean

Under Fixed each ocean cell takes the law the card sets. Under Dynamic each takes a 50 m mixed layer, cooled by the boundary-layer fluxes and relaxed toward the law over the Sea coupling time. The pickers offer Sea-surface temperature (°C) over open sea under either Mode, the law’s or the observed temperature under Fixed and the mixed layer’s under Dynamic, and under Dynamic add Sea-surface temperature anomaly (K, from the law). Under Dynamic the Air coupling is the sea ice’s conductance to the air, as the time to relax the lowest 150 hPa of air. The sea never reads below −1.8 °C, and a lower Polar value sets where the law crosses freezing. The law keeps a season of its own, by default a sixth of a cycle behind the global season.

A design whose land carries observed sea surface temperatures, such as Our Earth’s, adds a Law segment beneath the Mode segment, under either Mode. Idealised is the law the card sets. Observed reads each ocean cell’s monthly mean temperature, interpolated between the months’ middle days at the global season and no colder than −1.8 °C, in the law’s place wherever the cell carries a reading; the set-points, the swing and the season leave the card, the sketch draws the field’s zonal mean, and a line beneath the segment states its area mean at the season on show. Under Dynamic the mixed layer is laid at the observed temperatures and relaxes toward them. Our Earth’s temperatures are the 1991–2020 monthly means of the NOAA OI SST analysis. The temperatures follow the land, and a launch with the land unticked runs the law.

Moisture

Under On, the blank design’s Mode, each level carries a specific humidity whose condensation warms the level. The surface supplies humidity through the boundary-layer moisture flux alone, over open sea toward saturation at the Ocean card’s temperature and over each land type at its own multiple: Land, Desert, Mountain and Ice uptake, the last over land ice and sea ice alike.

The pickers offer Specific humidity (g/kg) and Relative humidity at every level, Column water (kg/m²), Precipitation and Evaporation (mm/day), Cloud amount, and Cloud cover (infrared) in °C.

The cloud amount is the mass-weighted mean of the levels’ cloud fractions beneath the 150 hPa level. The infrared field is the temperature a satellite would see from above, and under Off the surface level’s temperature. The precipitation is a running mean with a time constant of one model hour, emptied by Reset Simulation.

Sea Ice

Sea ice acts at both poles whatever the thermal forcing. Under the forcing, an iced cell relaxes as land ice does: toward the Air over Land equilibrium held at 0 °C at the ground and rising to that equilibrium at the boundary-layer top, at the surface air relaxation time whatever its latitude. The boundary layer takes it as land ice. The ice’s Dynamic Mode requires the sea’s, and returning the sea to Fixed returns the ice to Prescribed.

Under Prescribed, each cap’s extent in degrees of latitude from the pole is the Minimum extent plus the Amplitude times one plus the cosine of the global season read at the Season offset, the south cap reading the season half a cycle later.

A design whose land carries observed concentrations, such as Our Earth’s, adds a Rule segment under Prescribed. Idealised is the extent rule above. Observed freezes each ocean cell where the design’s monthly mean concentration, interpolated between the months’ middle days, reaches 15 %, and the card shows each cap’s frozen area in place of the four dials. Our Earth’s concentrations are the 1991–2020 means of the NSIDC Sea Ice Index. The concentrations follow the land, and a launch with the land unticked runs the extent rule.

Under Dynamic the ice evolves on the mixed layer, a cell counting as ice above the Threshold thickness. A longer Air coupling slows growth and melt, and a shorter Sea coupling confines the ice to where the law nears freezing. Choosing Dynamic lays ice once, one metre thick, on the cells the Prescribed rule freezes, and Reset Ice lays it again at the season on show without stopping the run. The Sea ice thickness plane (m) is zero under Prescribed.

Quasi-Geostrophic

Simulation

The f₀ multiplier scales f₀, which sets the pressure and temperature readings and the forcings’ temperature scale. The β multiplier, on the periodic domain and the β-plane channel only, scales the planetary vorticity gradient. A non-finite run may also need less heating or a weaker jet.

Friction

The card sets the Ekman friction at the ground.

Moisture

Mode is Off on a blank design and disabled on a channel. Under On, column water is advected by the surface wind, rains out near saturation and is recharged by the ocean toward 85 % of saturation over the Ocean recharge time. At a Latent Heating Magnitude of 0 the water is passive. The Multiple, with a snap point at the half-sine value, sets the Heating Profile at the interface its own stepper selects and moves no other, so the column mean moves with it.

The Forcing tab

The Thermal Forcing selector arms both column cards. Every control is live during a run, and every value but a sketch’s level or interface is saved with the design.

Cycle seasons advances the Season over the Cycle period, in model days, and, while the cycle runs, Reset Simulation restarts it with the model clock.

Full Primitive

Thermal Forcing

On, a blank design’s default, relaxes sea cells toward the Air over Ocean equilibrium and land, desert, mountain and sea-ice cells toward the Air over Land one, never both. Off removes only the relaxation and hides the cards below, unchanged.

Season & Diurnal Cycle

At Winter the solstice term of Polvani and Kushner (2002) cools the northern surface equilibrium by the column’s Seasonal swing times the sine of the latitude and warms the southern by as much. Summer reverses it, and the equinoxes carry none.

Diurnal Cycle Off disables the land’s diurnal heating. On, Time of day is the solar time at longitude 0, and Cycle days advances it with the model clock. Local time east of longitude 0 is later by the longitude’s fraction of a rotation, earlier under retrograde rotation.

Base Atmosphere

The card holds Held and Suarez’s equilibrium, from whose surface temperatures each column’s Equatorial and Polar are offsets. Moving the base’s Equatorial or Polar moves both columns’ offsets the other way, so neither column’s temperatures change, and the dial stops where an offset would leave −40 to 40 K. A column offset’s Earth-like mark follows the base.

Air over Ocean and Air over Land

Both columns stand at the global season.

Each sketch draws the target at the Layer selected, L0 the lowest.

The seed

With the forcing On a run starts from the ocean set’s equilibrium at every cell, at the Season shown, with a balancing westerly jet in each hemisphere, and with it Off at rest. Both carry a half-kelvin perturbation in zonal wave 6, whose wavenumber Regenerate initial state advances.

Quasi-Geostrophic

Thermal Forcing

Off, a blank design’s default, disables the column cards. On relaxes ocean cells toward the Air over Ocean equilibrium and land, desert and mountain cells toward the Air over Land one, at every tropospheric interface. The card’s season reshapes the equilibrium on a hemisphere and, on a flat domain while the cycle runs or under a Fixed season, scales the contrast by 2 at Winter, 1 at Spring and Autumn and 0.5 at Summer.

Air over Ocean

Populate with preset fills every interface, Uniform with 45 K at 40 days (10 days over land), Earth-like with 60 K (90 over land) tapered with height at 40 days. On this card Earth-like blends this below 4 km with the sea’s pull, a smaller, lagged contrast at a short time, and ticks Asymmetric relaxation.

On a flat domain the profile is Sine or Earth-like, the latter in a channel alone. The Thermal Profiles stepper selects the interface the sketch draws and the controls below edit.

Air over Land

The card matches Air over Ocean without Asymmetric relaxation or Heating time, and uses its profile.

Sea Ice

On a hemisphere under the forcing, unless Enable sea ice is unticked, ocean cells poleward of the ice edge are sea ice, relaxed by the Air over Land card, with the ocean’s drag. The extent, in degrees of latitude from the pole, is a cosine of the global season.

The Compute tab

The Engine card is a read-only report. Threads engage on Full Primitive and hemispheric Quasi-Geostrophic designs, as chosen on the Builder’s Compute card.

The Export tab

The Export Config File card writes the design and the map’s view settings, except the view mode, split seam, camera and Observables settings, as JSON that Import reads. The file begins with the version of the app that wrote it, app_version, which Import does not read. Include state snapshot (current fields) adds the state and the elapsed model time, which a run launched from the file shows as the Total of Model Run Time. The Last Generated JSON Preview is emptied on entering or leaving the tab and when the run ends.

Full Primitive. A sixteen-level snapshot occupies about 5 MB at 128 × 64 and 21 MB at 256 × 128, a third more when moist.

Quasi-Geostrophic. A moist eight-layer snapshot on 128 rings occupies about 8 MB.

Interact

Choosing a brush tool, Interact or Terrain, on the Orthographic globe switches the view to Winkel Tripel on the sphere or Polar on a hemisphere, and Watch restores the globe. Under a brush tool the right button or Control + left-drag pans, and adding Option / Alt to either pivots. Brush size is the radius on screen. A patch or stroke continues across a periodic edge and stops at a channel’s walls.

Interact, under Quasi-Geostrophic only, drops one patch per left click.

Terrain

Terrain pauses the run while active and disables Play and View Settings. A left drag draws with the dock’s pills, and Grab reads the clicked cell into the brush. Heights follow four actions, the first three working while the button is held, in 10 m steps.

• Raise lifts the terrain, fastest at the brush’s centre, up to the design’s ceiling.
• Lower sinks it toward the sea’s level.
• Smooth relaxes heights toward their neighbours’ mean, leaving the sea unchanged.
• Place lays the height slider’s height under the brush, sloping to the terrain at its ring.

A cell’s material sets its drag and, while the thermal forcing is on, its equilibrium. Undo/Redo covers the last hundred strokes, a history dropped with the design. Terrain is part of the design and survives Reset Simulation.

Full Primitive

The Tool pill reads Pan, Terrain and Height, and a cell’s type and height are set apart. Terrain lays a type, Land, Desert, Mountain (ground rough below the grid’s scale), Land ice (permanent) or Ocean, each land type keeping the ground’s height and Ocean clearing it; Grab reads the type. Height applies the four actions to land of every type, leaving the sea and the sea ice unchanged, and Place lays the Height slider’s height. Each type has its own drag and uptake, and every land type relaxes toward the Air over Land equilibrium.

Strokes land on a 1024 × 512 painting grid and reach the model’s grid only when the tool is left. The model smooths heights, so one painted cell becomes a low hill. The Height slider marks the levels’ reference heights and stops at the ceiling, 3,410 m on the Blank design. A smaller Exponent in the Builder raises the ceiling, and higher stored heights are carried at it.

Quasi-Geostrophic

The Tool pill reads Pan, Grab and the materials, and Grab reads the height too. Desert is land that yields no moisture, and Mountain takes the Mountain action pill’s actions, Place at the Mountain height slider’s height; Lower sinks a mountain to plain land.

The Mountain height slider’s marks stand 30% of the way into each layer. A mountain carries topographic PV in the layer its crest reaches, strongest at a hemisphere’s pole and nearly absent at its equator. Land and desert carry none. Layers a mountain fills obstruct the flow and show nothing over it.

The Mountain blocking field is the non-dimensional mountain height at the crest. Above about 0.85 a ridge would overturn the flow and above about 1 an isolated hill would split it, neither of which quasi-geostrophy represents.

The Observables view

The Observables view plots the ticked series of an Observable class, each with a dashed running average over the Full run or the trailing Time window, the plot’s span. Having no map, the view disables the brush tools.

Under Split the brush tools work on the map.