As snow accumulates, it settles or compacts under its own weight, or by the action of the wind, resulting in an increase in the dry density and a decrease in the porosity. A growth curve approach was chosen to compute compaction effects. The new relative dry density, TRHO after an interval of DT hours is determined as:

MRHO = the maximum specified relative dry density,
KC = the compaction time constant (h),
A (1/°C) and B (h) are coefficients.

Similar to KM and TBAS, the seasonal variation is also applied to MRHO.

The final dry density (due to compaction) for the interval DT is determined according to:

The snowpack depth is also updated with new dry density.