Thermal

Sun simulation · thermal on terrain

Date & Time

Simulation date

Target date for sun position and weather data.

UTC offset (h)

Interval (min)

Min sun elevation (°)

Scenarios with sun below this angle are skipped.

Terrain

Sim zoom

Mesh zoom

Zoom 12 ≈ 30 m/px (sim), zoom 14 ≈ 7 m/px (mesh).

Heating

ERA5 auto-calibrate max_heat

Fetches ERA5 data to derive max_heat from observations.

Weather mode

Typical (5-years average of ERA5 data around this date.) Exact (past date only; ERA5 data for specific date)

max_heat (K) — manual fallback

Peak ground-air temperature anomaly under full insolation.

ERA5 window (days)

Diffuse fraction

Env. lapse rate (K/km)

Environmental lapse rate. Higher = more unstable atmosphere.

Solar Radiation Model

T_atm base

T_atm exponent

Kasten-Czeplak transmittance: T_atm = T_base^(AM^exp). Higher base → more solar energy, e.g. 0.80 for high-altitude clear days.

Incidence smoothing σ

Clear-sky threshold (W/m²)

Incidence smoothing reduces cliff artefacts. Clear-sky threshold filters ERA5 calibration to sunny hours only.

Thermal Inertia

τ hours (reference grassland)

Time constant for ground temperature to reach solar equilibrium. ~1 h bare rock, ~1.5 h mixed, ~3 h forest/water.

Land cover smoothing σ

Gaussian blur on the land-cover thermal factor map. Blends abrupt forest/grassland boundaries.

Terrain Analysis

Convexity smooth σ

Trigger blur σ

Convexity weight (0–1)

Trigger factor = w·convexity + (1−w)·LC boundary. Higher w favours terrain peaks; lower w favours forest edges.

Thermal Release

K_release (h⁻¹)

Threshold (K)

Accumulated heat above threshold releases at trigger zones.

Advection

V_advect_max (m/h)

Ref slope

Anabatic flow speed ceiling and reference slope (tan angle).

K_collect (collector suction)

Strength of dT-gradient suction: collectors bleed heat toward trigger zones. 0 = pure orographic flow; higher = stronger collector→trigger funnelling.

Flow smooth σ

CFL safety factor

Flow smoothing blurs the advection vector field. CFL safety factor controls substep count (lower = more substeps, more stable).

Diurnal Model

Diurnal amplitude (K)

Peak hour (local)

Cosine model for filling missing ERA5 hourly temperature values. Amplitude = daily range / 2.

Output

Arrow step (px)

Downsample flow arrows: every N-th sim grid cell.