Snow‐melt degree‐day ratios determined from snow‐lab data

Abstract

Observations made at the Central Sierra Snow Laboratory in California and the Upper Columbia Snow Laboratory in western Montana have been used to determine the ratio of the amount of snow melt to the accumulated number of degree days or degree hours above selected base temperatures during the late spring melting season. The use of degree days was found to give smaller errors of estimation than degree hours, and a base temperature of 32°F gave smaller errors of estimation than other bases tried. The ratio was found to be smaller for greater forest cover and to increase during the melting season. No relation was found between the ratio and average wind, humidity, or cloudiness. These, of course, have important physical effects on the heat supply to a snow cover, but variations in their effect could be obscured by the fact that they were averaged over weekly or longer periods, and some of their effect may be included in the time‐of‐year parameter.