Publication Date:
2023-07-10
Description:
Interception of snow by trees is the dominant control on snow accumulation patterns in forest environments but is notoriously difficult to observe and model. In this work, we use time-lapse photography to create a timeseries of snow unloading to link with local meteorological measurements to better understand how snow unloads from the canopy. Our results support previous studies that air temperature drives unloading when temperatures are above 0 ºC. However, we found that below 0°C multiple variables interact when unloading occurs. For example, unloading occurs when shortwave radiation exceeds 400 Wm〈sup〉-2 〈/sup〉for at least one hour, even while air temperatures remain negative. While it is well known that shortwave radiation heats canopy elements, it is rarely included in unloading parameterizations. Additionally, when air temperatures were below -3ºC, wind speeds as low as 2 to 4 ms〈sup〉-1〈/sup〉 could unload snow, but wind speeds greater than 5 ms〈sup〉-1〈/sup〉 were needed when temperatures were warmer than -3ºC. This can be explained by the greater cohesivity of snow at temperatures above -3ºC. The concept of snow cohesion changing with temperature is often included in the loading aspect of models, but not considered in the unloading counterpart. As a result of these observations, we adapted existing unloading parameterizations to account for the relationships between air temperature, wind speed, and incoming solar radiation statistically. We present model results demonstrating the impact of incorporating variable interactions in the Structure for Unifying Multiple Modelling Alternatives (SUMMA) modular hydrologic modelling framework.
Language:
English
Type:
info:eu-repo/semantics/conferenceObject
Permalink