Towards a 3-Dimensional Model of Forest Heat Contributions to Snowpack
Thermodynamics: Determining internal snowpack temperature responses to
energy balance drivers in the Australian Alps
Abstract
Research on modification to snowpacks as a result of forest disturbance
has typically focused on spatiotemporal patterns of snow depth and snow
water equivalent, snowpack energy fluxes, and melt/ablation
characteristics. However, little work has been conducted on
relationships between tree trunks and snowpack dynamics. Insight into
drivers of internal snowpack thermodynamics around trees and their
response to forest disturbance is crucial to understanding hydrological
processes in forested regions of the cryosphere, especially as forest
disturbance through climate change continues. This work investigates
relationships between energy fluxes and thermodynamic patterns
surrounding tree trunks and within the greater snowpacks of forest
stands in the Snowy Mountains of the Australian Alps. Measurements of
vertical and horizontal snowpack temperature profiles and sub-canopy
energy fluxes were collected during the 2018 winter season in
non-disturbed and fire-disturbed Eucalyptus pauciflora (Snow Gum)
stands. Primary heat sources were identified for each measurement
location in the snowpack through employing the Random Forest machine
learning regression method. Preliminary results indicate that soil heat
flux is the dominant control on snowpack temperature at all locations in
the un-disturbed forest stand. However, outgoing longwave radiation is
shown to be the prevalent driver at numerous locations within the
fire-disturbed stand that are close to the snowpack surface and tree
well. This work aims to develop the physical basis for a 3-dimensional
thermodynamic model of snowpacks contained in forests that could be used
in conjunction with existing 1-dimensional snowpack models to determine
melt and variability.