Document Type

Thesis

Date of Degree Completion

Spring 2017

Degree Name

Master of Science (MS)

Department

Geological Sciences

Committee Chair

Susan Kaspari

Second Committee Member

Carey Gazis

Third Committee Member

Megan Walsh

Abstract

Wildfires in the seasonal snow zone affect both snow accumulation and ablation patterns by decreasing forest canopy and depositing light absorbing impurities (LAI) on the snowpack. LAI such as black carbon (BC), burned woody debris, and dust reduce snow albedo (reflectance), accelerate melt, and affect the timing and availability of water resources. Charred trees in post-wildfire forests provide a significant source of BC that is deposited on the snowpack for years following a wildfire, and this effect varies with burn conditions and forest structure. Snow samples were gathered from five sites of varying burn age (0.7, 2.7, 3.8, and 9.8 years) and burn severity throughout the Cascade Mountain Range in Washington State to characterize the spatial and temporal variability of LAI deposition and quantify changes in reflectance by LAI. BC and other LAI concentrations in snow samples were measured using a Single Particle Soot Photometer (SP2), gravimetric filtration, and spectroradiometer analysis. These analyses demonstrate that the greatest BC deposition is localized to high burn severity areas, and decreases significantly within ten years of a wildfire. Spectroradiometer data demonstrate that BC has the strongest effect on reduced albedo per unit mass of all impurities. SNOTEL data from Table Mountain indicates that complete snowmelt occurs an average of 48 days earlier in post-wildfire forests, compared to pre-fire conditions and regardless of temperature.

Available for download on Wednesday, June 26, 2019

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