Quantifying the Impact of Synoptic Weather Types on Snowpack Energy Flux in the Snowy Mountains, Australia

Seasonal snowpack contained within the Snowy Mountains of Southeast Australia accounts for approximately two thirds of the area’s annual water and is crucial to agriculture, hydroelectric energy production, and recreation. Insight into atmospheric drivers of snowpack ablation and their characteristics is vital to understanding seasonal and sub-seasonal snowpack dynamics and subsequent hydrology of the area. Energy flux data from an eddy covariance (EC) instrumentation site located at the headwaters of the Pipers Creek catchment was collected during the 2016 and 2017 winter seasons. Periods with homogeneous snow cover were determined using ground/snow surface temperature data, soil moisture and temperature characteristics, and planetary surface albedo. European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim reanalysis products were gathered for days that corresponded to the identified homogeneous snow cover periods. Daily regional synoptic characteristics were then investigated and dominant synoptic weather types were determined using the k-means clustering technique on the ERA-Interim data. Snow cover days were categorized by their corresponding synoptic type and mean atmospheric characteristics were determined by identifying mean values between days in the period. Snowpack energy flux measurements for each synoptic type were then collated and analyzed. This paper compares the energy flux from an array of atmospheric variables under each dominant synoptic weather type. This is an important step towards the identification of primary snow ablation synoptic patterns in Australia and their impact on snowpack water storage and inflows in the Snowy Mountains region.