Comparison of ground-based and airborne snow surface albedo parameterizations in an alpine watershed: Impact on snowpack mass balance

[1] Two commonly used snow surface albedo models were evaluated using albedo data from the Airborne Visible/Infrared Imaging Spectroradiometer (AVIRIS), and their influence on snowmelt timing and magnitude was assessed using a net radiation/ temperature index snowmelt model, a series of satellite-based snow covered area scenes, and on-site snow surveys. Albedo estimates using an explicit representation of snow surface temperature, snow age, and solar illumination angle, based on the Biosphere Atmosphere Transfer Scheme ( BATS), were within the 0.02 AVIRIS measurement error for 78% of the snow-covered portions of the watershed. Conversely, albedo values estimated using a simple model based solely on snow surface age underestimated AVIRIS-observed albedo. Correlations between the timing of snowmelt and observed runoff using the BATS albedo model (R-2 = 0.69) were significantly better than those using the age-based approach (R-2 = 0.59) and were comparable to using AVIRIS data (R-2 = 0.73). Snow extent was simulated most accurately with the AVIRIS parameterization; average map accuracy was 79 and 10% greater than when using the age-based and BATS albedo parameterizations, respectively. The error in snow water equivalent for April was 14% for BATS versus 39% for the age-based albedo; however, it was less than 1% for simulations using AVIRIS albedo data. Thus the BATS albedo estimates performed better than the age-based albedo but did not outperform simulations using AVIRIS albedo data.