Alpine wind speed and blowing snow trend identification and analysis

Abstract

The substantial quantity of climate change related analyses has resulted in increased research efforts concerning temporal wind speed trends. A change in wind speeds over time could have a widespread effect on snow transport and distribution in alpine regions. Since alpine meteorological stations are sparsely distributed, the intentions of this research were to explore North American Regional Reanalysis (NARR) to assess long-term trends of atmospheric conditions affecting snow transport with greater spatial coverage. NARR is a consistent, continuous and long-term dataset spanning the extent of North America at a spatial resolution of 32 km2 grids. NARR data were compared to two alpine sites (Niwot Ridge, Colorado and Glacier Lakes Ecological Experiments Station, Wyoming) from1989 to 2009. Multiple analyses were conducted to evaluate dataset agreement and temporal trends of alpine climatic conditions at the annual, seasonal and daily scales. The correlation of temperature, precipitation and wind speed between NARR and alpine in situ datasets showed temperature data as correlated, but wind and precipitation lacked agreement. NARR wind speed data were systematically lower when compared to observational data for both locations, but the frequency of wind events was captured. Thus, to more accurately assess blowing snow dynamics using NARR additional methods would be needed to relate the lower wind speed values to the extent of blowing snow. Trend analyses of wind speed datasets for each temporal scale (annual, seasonal and daily) showed slight trends, minimal significance and trends were not significantly different between NARR and in situ data. The statistical similarities were observed for trends with opposite signatures and slopes and a result of weak trends. Additional blowing snow analyses were conducted using temperature, wind speed and precipitation to estimate probable blowing snow events. The low agreement between NARR and observational data for wind speed and precipitation parameters prohibited the use of NARR to assess blowing snow processes and expand spatial and temporal coverage.