A Comparison of Degree-day Factors for Snowmelt Between Three Cedar Stands and an Opening

Abstract

　Snowmelt and meteorological observations were conducted at the opening and three cedar stands with different sky view factors. The sky view factors of cedar stands A, B, and C were, respectively, 17.8%, 5.2%, and 2.4%. Snow water equivalent (SWE) at the stands on 9 March decreased concomitantly with the decreasing sky view factor. SWE at each site on 12 April in order from smallest to largest was the opening, the cedar stands C, A, and B. Melt-off dates were the same order from earliest to latest. The degree-day factors k calculated based on the snowmelt measurements for 21 days were also the same order from largest to smallest. The values of k estimated using the daily average air temperature at the open site for the opening, the cedar stands A, B, and C were, respectively, 4.09 mm °C^-1 day^-1, 2.34 mm °C^-1 day^-1, 2.13 mm °C^-1 day^-1, and 2.38 mm °C^-1 day^-1, whereas k estimated based on the daily average air temperature measured at each site for stands A, B, and C were, respectively, 2.83 mm °C ^-1 day^-1, 2.70 mm °C^-1 day^-1, and 2.90 mm °C^-1 day^-1. Dates of melt-off at all sites were reproduced using values of k except for cedar stand A, where snow disappeared 4-5 days earlier than the estimation. Sky view factors were insufficient to elucidate the magnitude relation on k between stands B and C. Instead, the living branch height and the amount of litter might contribute to it.