Snow surveys using a snowtube and thermometer recorded the following data from a

ID: 907100 • Letter: S

Question

Snow surveys using a snowtube and thermometer recorded the following data from a snow course on two different dates. The snow temperature was measured the midpoint of the snow depth to represent average snowpack temperature. NOTE: SWE: snow water equivalent. (a) Calculate the snow density (g/cm^3) and cold content (J/m^2) for March 2. (b) Calculate the snow density (g/m^3) and cold content (J/m^2) for March 17. (c). How much energy must be added to the snowpack on each date to initiate the water output phase (J/m^2).

Explanation / Answer

(a) : we can calcualte the snow density from the following formulae

SWE = Zs x (density of snow / density of pure water)

=> Density of snow = SWE x (density of pure water) / Zs

Where SWE = snow water equivalent

Zs = Snow depth.

Density of pure water = 1 g/cm3

Measurement for March 2:

For station-1: Density of snow = SWE x (density of pure water) / Zs = 29cm x (1 g.cm-3) / 92cm = 0.315 g.cm-3

For station-2: Density of snow = 30cm x (1 g.cm-3) / 94cm = 0.319 g.cm-3

For station-3: Density of snow = 33cm x (1 g.cm-3) / 105cm = 0.314 g.cm-3

For station-4: Density of snow = 29cm x (1 g.cm-3) / 93cm = 0.312 g.cm-3

For station-5: Density of snow = 32cm x (1 g.cm-3) / 96cm = 0.333 g.cm-3

Average snow density for March - 2

= (0.315 +0.319 +0.314 +0.312+0.333) / 5 = 0.319 g.cm-3

Cold content(Qcc): It is the amount of energy required to raise the average snow pack temperature to melting point (0 DegC) and can be calculated from the following formulae

Cold content, Qcc = - Ci x (density of ice) x Zs x (Ts - 0)

where Ci = heat capacity of ice = 2102 JKg-1DegC-1

Zs = snow depth

Since we need to find Qcc in J/m2, we need to convert the given data into SI system

For station-1 : Zs = 92 cm = 92 cm x (1 m / 100 cm) = 0.92 m

Density of ice = 0.315 g.cm-3 = 0.315 g.cm-3 x (1000 Kg.m-3 / 1 g.cm-3) = 315 Kg.m-3

Ts = - 6 DegC