Thursday, February 24, 2011, 4:30PM - 5:30PM
Civil Engineering, UCLA
Full title: The use of detailed forest structure to explain plot scale snowmelt patterns in a conifer forest: improving physically based model representation of sub-canopy hydrometeorology. Results from a southern Sierra Nevada CZO, Sequoia National Park, CA.
Abstract: We present the use of detailed canopy structure as measured by hemispherical photographs taken at locations coinciding with 24 ultrasonic snow depth sensors, coupled with above canopy radiation measurements, to estimate sub-canopy solar irradiance. We relate both the detailed canopy structure and simulated direct beam fluxes to three years of measured sub-canopy snow dynamics recorded by the automated depth sensors and repeated density measurements (i.e. SWE ablation indicators) along a sub-alpine elevation gradient. The relationships observed at the scale of our forested research plots serve to inform optimal treatment of canopy structure in physically based snow models as well as to guide the use of increasingly available LiDAR data for basin level hydrological applications. To improve understanding of the feedbacks between atmospheric processes, forest canopy structure and the spatiotemporal evolution of snow properties and soil moisture, we apply a one-dimensional snow, vegetation and soil model (SNOWPACK) with a modified treatment of high resolution canopy transmissivity. The results of this work may be used to inform the development of improved forest cover parameterizations necessary for regional climate models, macro-scale hydrologic models, and ecosystem models.