Measuring snow accumulation and ablation dynamics during rain-on-snow events: innovative measurement techniques

Rain-on-snow (ROS) is the primary generator of peak flow events in mountainous coastal regions of North America. Uncertainty remains as to the role of forest canopy interception leading up to and during ROS events. Much of this uncertainty can be attributed to a lack of suitable techniques to collect data during ROS, due in part to the dynamic nature of climatic conditions, particularly related to snow accumulation and melt. We supplemented a meteorological network with non-weighing snow melt lysimeters, suspended spring scales to measure snow throughfall and an automated time lapse photography network to monitor state of precipitation (rain vs. snow), snow accumulation/ablation, canopy interception and unloading of snow from the canopy. Image analysis software allowed for the extraction of data from images. Rapid loading and unloading of snow from the canopy, closely linked to changes in temperature, was observed using this approach. We were also able to continuously monitor throughfall snow water equivalent using low cost suspended spring scales. This experimental design allowed us to capture information previously unavailable without direct observation. Copyright (C) 2008 John Wiley & Sons, Ltd.