Table 4. Variables and initial conditions for the Density/Depth section

Table 4. Variables and initial conditions for the Density/Depth section.

Initial

Variable

Units

compaction time constant

96

h

MELT_I

melted solid water when LWC <= LWCAP

0

mm of H2O/h

MELT_II

melted solid water when LWC > LWCAP

0

mm of H2O/h

MRHO

maximum dry density for snowpack

0.35

vol/vol

RHO

dry density of snowpack

solid water content of snowpack

first estimate of dry density in compaction

0.203

vol/vol

TRHO_II

second estimate of dry density in compaction

SDEPt1 = SDEPt 0 + dt(SNOW_IN ∆t + COMPACTION ∆t - SNOWMELT∆t )

(13)

where SNOW_IN = DSNOW

(14)

COMPACTION = COMPAC_CALC

(15)

SNOWMELT = (MELT_I + MELT_II) / RHO

(16)

The following equations describe the methods by which density is calculated. To complete the

numerical integrations, several objects, such as RHO, TRHO_DEL, TRHO_I and TRHO_II, were

created to calculate density:*

RHO = SWC/SDEP

(17)

Equation 18 is a delayed density calculation since this equation calculates density one dt (time inter-

val) later than eq 17, 19 and the first part of eq 20:

TRHO_DEL = [RHO MRHO]/[RHO + (MRHO RHO)EXP(1/KC)]t 0

(18)

TRHO_It1 = TRHO_It 0 + dt(TRHO_I_IN ∆t + TRHO_I_OUT∆t )

(19)

then TRHO_II = [TRHO_I MRHO]/[TRHO_I+(MRHO-TRHO_I)

If DSNOW = 0

EXP(1/KC)]

If DSNOW > 0

then TRHO_II = TRHO_DEL

(20)

KC = B EXP( A TEMP).

(21)

Equation 17 is used to calculate eq 18. Equation 19 is used to calculate eq 20 in the absence of

snowfall, while eq 18 is used to calculate eq 23 during snowfall. Equation 21 is used by equations 18

and 20. Equations 1721 are used to imitate the order of operations shown in Figure A.2 in the

GAWSER manual.

* Equations

17 and 21 are equivalent to equations A.5 and A.11b in the GAWSER manual.

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