Microphysics

One-moment bulk microphysics scheme, which includes:

• terminal velocity of precipitation
• condensation and evaporation of cloud liquid water and deposition and sublimation of cloud ice (relaxation to equilibrium)
• autoconversion of cloud liquid water into rain and of cloud ice into snow
• accretion due to collisions between categories of condensed species
• evaporation and sublimation of hydrometeors
• melting of snow into rain

v0_rai(param_set, ρ)

• param_set - abstract set with earth parameters
• ρ air density

Returns the proportionality coefficient in terminal velocity(r/r0).

n0_sno(snow_param_set, q_sno, ρ)

• snow_param_set - abstract set with snow parameters
• q_sno - snow specific humidity
• ρ - air density

Returns the intercept parameter of the assumed Marshall-Palmer distribution of snow particles.

τ_relax(liquid_param_set)
τ_relax(ice_param_set)

• liquid_param_set - abstract set with cloud liquid water parameters
• ice_param_set - abstract set with cloud ice parameters

Returns the relaxation timescale for condensation and evaporation of cloud liquid water or the relaxation timescale for sublimation and deposition of cloud ice.

lambda(q, ρ, n0, m0, me, r0, χm, Δm)

• q - specific humidity of rain, ice or snow
• ρ - air density
• n0 - size distribution parameter
• m0, me, χm, Δm, r0 - mass(radius) parameters

Returns the rate parameter of the assumed size distribution of particles (rain drops, ice crystals, snow crystals).

unpack_params(param_set, microphysics_param_set, ρ, q_)

• param_set - abstract set with earth parameters
• microphysics_param_set - abstract set with microphysics parameters
• q_ - specific humidity
• ρ - air density

Utility function that unpacks microphysics parameters.

G_func(param_set, T, Liquid())
G_func(param_set, T, Ice())

• param_set - abstract set with earth parameters
• T - air temperature
• Liquid(), Ice() - liquid or ice phase to dispatch over.

Utility function combining thermal conductivity and vapor diffusivity effects.

terminal_velocity(param_set, precip_param_set, ρ, q_)

• param_set - abstract set with earth parameters
• precip_param_set - abstract set with rain or snow parameters
• ρ - air density
• q_ - rain or snow specific humidity

Returns the mass weighted average terminal velocity assuming a Marshall-Palmer (1948) distribution of rain drops and snow crystals.

conv_q_vap_to_q_liq_ice(liquid_param_set::ALPS, q_sat, q)
conv_q_vap_to_q_liq_ice(ice_param_set::AIPS, q_sat, q)

• liquid_param_set - abstract set with cloud water parameters
• ice_param_set - abstract set with cloud ice parameters
• q_sat - PhasePartition at equilibrium
• q - current PhasePartition

Returns the cloud water tendency due to condensation and evaporation or cloud ice tendency due to sublimation and vapor deposition. The tendency is obtained assuming a relaxation to equilibrium with a constant timescale.

conv_q_liq_to_q_rai(rain_param_set, q_liq)

• rain_param_set - abstract set with rain microphysics parameters
• q_liq - liquid water specific humidity

Returns the q_rai tendency due to collisions between cloud droplets (autoconversion), parametrized following Kessler (1995).

conv_q_ice_to_q_sno(param_set, ice_param_set, q, ρ, T)

• param_set - abstract set with earth parameters
• ice_param_set - abstract set with ice microphysics parameters
• q - phase partition
• ρ - air density
• T - air temperature

Returns the q_sno tendency due to autoconversion from ice. Parameterized following Harrington et al. (1996) and Kaul et al. (2015).

accretion(param_set, cloud_param_set, precip_param_set, q_clo, q_pre, ρ)

• param_set - abstract set with earth parameters
• cloud_param_set - abstract set with cloud water or cloud ice parameters
• precip_param_set - abstract set with rain or snow parameters
• q_clo - cloud water or cloud ice specific humidity
• q_pre - rain water or snow specific humidity
• ρ - rain water or snow specific humidity

Returns the sink of cloud water (liquid or ice) due to collisions with precipitating water (rain or snow).

accretion_rain_sink(param_set, ice_param_set, rain_param_set,
                    q_ice, q_rai, ρ)

• param_set - abstract set with earth parameters
• ice_param_set - abstract set with cloud ice parameters
• rain_param_set - abstract set with rain parameters
• q_ice - cloud ice specific humidity
• q_rai - rain water specific humidity
• ρ - air density

Returns the sink of rain water (partial source of snow) due to collisions with cloud ice.

accretion_snow_rain(param_set, i_param_set, j_param_set, q_i, q_j, ρ)

• i - snow for temperatures below freezing or rain for temperatures above freezing
• j - rain for temperatures below freezing or rain for temperatures above freezing
• param_set - abstract set with earth parameters
• i_param_set, j_param_set - abstract set with snow or rain microphysics parameters
• q_ - specific humidity of snow or rain
• ρ - air density

Returns the accretion rate between rain and snow. Collisions between rain and snow result in snow at temperatures below freezing and in rain at temperatures above freezing.

evaporation_sublimation(param_set, rain_param_set, q, q_rai, ρ, T)
evaporation_sublimation(param_set, snow_param_set, q, q_sno, ρ, T)

• param_set - abstract set with earth parameters
• rain_param_set - abstract set with rain microphysics parameters
• snow_param_set - abstract set with snow microphysics parameters
• q - phase partition
• q_rai - rain specific humidity
• q_sno - snow specific humidity
• ρ - air density
• T - air temperature

Returns the tendency due to rain evaporation or snow sublimation.

snow_melt(param_set, snow_param_set, q_sno, ρ, T)

• param_set - abstract set with earth parameters
• snow_param_set - abstract set with snow microphysics parameters
• q_sno - snow water specific humidity
• ρ - air density
• T - air temperature

Returns the tendency due to snow melt.