Snow physics research update
A recent research project involving Snowy Hydro Ltd, the University of Western Australia and the University of Queensland, investigated the hydrometeorology of the Australian snowpack and highlighted the fundamentally important role that individual meteorological events play in its development. Fieldwork took place in the Pipers Creek catchment, adjacent to Perisher Valley, with a particular focus on collecting a comprehensive new set of physical measurements.
There were three main aspects to this research:
– The spatial and temporal variability of the snowpack. Analysis of snow survey data showed that marginal snowpacks exhibit high variability and unique dynamical characteristics – we can’t just think of them as incrementally warmer versions of a textbook ’cold climate’ snowpack. This has important consequences for how we can use point measurements (such as those from the snow course at Spencers Creek) to represent the surrounding catchment or the snowpack of the region as a whole.
– The snowpack energy balance and drivers of snowmelt. This study involved the first measurements of the energy balance of the Australian snowpack, establishing the importance of longwave and shortwave radiation to snowmelt in this environment. Although rain-on-snow is important to the hydrology of our region, it was shown that the energy provided to the snowpack by rain is small; instead, the higher snowmelt during these events is driven by increased turbulent fluxes and longwave radiation.
– The contribution of snowmelt to streamflow variability. While it has been shown elsewhere that warmer snowpacks are among the most vulnerable to global warming, less snow doesn’t necessarily translate to a similarly large impact on water resources in these environments. The Australian Alps already feature a short and highly variable snow season, and precipitation falling as rain is common throughout winter. A shift towards proportionally less snowfall is, hydrologically speaking, not as much of a departure from existing conditions as it will be in colder climates, where greater changes in the timing of snowmelt are expected. Of more significance to streamflow in the Australian Alps are observed declines in total precipitation and likely increases in evapotranspiration.
For more details, check out the following papers:
Bilish, S. P., McGowan, H. A., & Callow, J. N. (2018). Energy balance and snowmelt drivers of a marginal subalpine snowpack. Hydrological Processes, 32, 3837–3851. https://doi.org/10.1002/hyp.13293
Bilish, S. P., Callow, J. N., McGrath, G. S., & McGowan, H. A. (2019). Spatial controls on the distribution and dynamics of a marginal snowpack in the Australian Alps. Hydrological Processes, 33, 1739-1755. https://doi.org/10.1002/hyp.13435
Bilish, S. P., Callow, J. N., & McGowan, H. A. (2019). Streamflow variability and the role of snowmelt in a marginal snow environment. Manuscript submitted for publication.
