Retrieval of wintertime monthly climatological precipitation from snow survey data

Abstract:

For the purposes of developing high resolution maps of monthly climate normals for precipitation in British Columbia, the data-sparse high elevation regions present a substantial problem. These locations suffer from a sparse observational network to begin with and the measurements sites that do exist are often unable to accurately record solid precipitation amounts owing to undercatch associated with blowing snow, instrument capping, instrument failure, bridging over snow pillows or grossly inadequate instrumentation such as tipping buckets. British Columbia's River Forecast centre operates a fairly extensive network of snow survey sites which are accessed on a monthly basis beginning as early as January in a given year and running through June at sites where snow is present. These measurements have long temporal histories which enables their use as proxies for monthly precipitation during the months when instrument measurement is most difficult. These are proxy indicators because SWE on the ground is a product of accumulated snow minus evaporation and any meltwater that has percolated through the snowpack. We present a simple method for retrieving monthly climatological precipitation from snow survey sites and demonstrate the effects of including the data in construction of Parameter Regression on Independent Slopes Model precipitation climatology maps.