Output Variables

This section describes all output variables generated by pySnowClim, their units, and physical meaning.

Variable Categories

pySnowClim generates comprehensive outputs organized into several categories:

• Snow State Variables: Physical properties of the snowpack

• Mass Balance Components: Inputs and outputs of water/snow

• Energy Balance Components: Heat fluxes and energy transfers

• Surface Properties: Characteristics of the snow surface

• Internal Snowpack Properties: Subsurface conditions

Complete Variable List

Snow State Variables

Variable Name	Units	Description
SnowWaterEq	mm	Snow water equivalent - total amount of water stored as snow
SnowDepth	mm	Physical depth of snowpack from ground surface
SnowDensity	kg/m³	Bulk density of the snowpack
SnowfallWaterEq	mm/timestep	Water equivalent of new snowfall during timestep
SnowTemp	°C	Temperature of the snow surface

Mass Balance Components

Variable Name	Units	Description
SnowMelt	mm/timestep	Amount of snow melted during timestep
Sublimation	mm/timestep	Snow lost to sublimation (positive values)
Condensation	mm/timestep	Water gained from vapor condensation (negative sublimation)
RefrozenWater	mm/timestep	Liquid water that refroze within the snowpack
Runoff	mm/timestep	Surface runoff from snowpack (melt + rain excess)
RaininSnow	mm/timestep	Rainfall remaining in snowpack after water drainage
PackWater	mm	Total liquid water currently stored in snowpack

Energy Balance Components

Variable Name	Units	Description
Energy	kJ/m²/timestep	Net energy flux at snow surface (positive = energy input)
Q_sensible	kJ/m²/timestep	Sensible heat flux between air and snow surface
Q_latent	kJ/m²/timestep	Latent heat flux (evaporation/sublimation/condensation)
Q_precip	kJ/m²/timestep	Heat input from liquid precipitation
SW_down	kJ/m²/timestep	Incoming shortwave (solar) radiation
SW_up	kJ/m²/timestep	Reflected shortwave radiation
LW_down	kJ/m²/timestep	Incoming longwave (atmospheric) radiation
LW_up	kJ/m²/timestep	Outgoing longwave radiation from snow surface
MeltEnergy	kJ/m²/timestep	Energy consumed by melting process
Gf	kJ/m²/timestep	Ground heat flux (typically small positive value)

Surface Properties

Variable Name	Units	Description
Albedo	dimensionless	Surface albedo (fraction of solar radiation reflected)
ExistSnow	binary	Snow presence flag (1 = snow present, 0 = no snow)

Internal Snowpack Properties

Variable Name	Units	Description
PackCC	kJ/m²	Cold content of snowpack (energy deficit below 0°C)
CCenergy	kJ/m²/timestep	Energy used to eliminate cold content during timestep
CCsnowfall	kJ/m²/timestep	Cold content added by new snowfall

Derived Variables

Additional variables that can be calculated from primary outputs:

Derived Variable	Units	Calculation	Description
Net_SW	kJ/m²/timestep	SW_down - SW_up	Net shortwave radiation
Net_LW	kJ/m²/timestep	LW_down - LW_up	Net longwave radiation
Net_Radiation	kJ/m²/timestep	Net_SW + Net_LW	Total net radiative flux
Mass_Balance	mm/timestep	SnowfallWaterEq - SnowMelt - Sublimation + RefrozenWater	Net mass change of snowpack

Understanding the Variables

Sign Conventions

Energy Fluxes:

• Positive values: Energy input to snowpack (warming)

• Negative values: Energy loss from snowpack (cooling)

Mass Fluxes:

• Positive values: Mass gain or output from snowpack

• Negative values: Mass loss (for Sublimation, negative values indicate condensation)

Temperature:

• All temperatures in Celsius

• Snow surface temperature ≤ 0°C

• Cold content always ≤ 0 (represents energy deficit)

Temporal Considerations

Instantaneous vs. Accumulated:

• Most variables represent fluxes or changes during the timestep

• State variables (SWE, depth, temperature) represent conditions at end of timestep

• Some variables (PackWater, PackCC) represent current storage amounts

Timestep Dependencies:

• Flux variables scale with timestep length

• Daily timesteps will have larger absolute values than hourly

• Rate calculations should account for timestep duration