Document Type

Thesis

Date of Degree Completion

Winter 2018

Degree Name

Master of Science (MS)

Department

Geological Sciences

Committee Chair

Susan Kaspari

Second Committee Member

Angela Halfpenny

Third Committee Member

Carey Gazis

Fourth Committee Member

Chris Mattinson

Abstract

Snow and glaciers are receding at a global scale. Warming temperatures are often identified as the dominant cause of this decline; however, deposition of light absorbing aerosols (LAA), including black carbon, mineral dust and organics onto snow and glacier surfaces can be an even larger driver of melt in some regions (Skiles et al., 2012). Attempts to partition the relative contribution of different types of LAA to snow and glacier melt has been limited by the uncertainties in the LAA optical properties (Kaspari et al., 2014). A new hyperspectral imaging microscope spectrometer (HIMS) method was recently developed to measure LAA spectral reflectance at the particle scale. The objectives for this study are to do the following: 1. Advance the HIMS method by determining the reproducibility of a iv 99% reflective standard over time, improve sample preparation routines for both 3D and 2D samples, critique region of interest (ROI) selection, and develop an analysis method for 2D samples. 2. Use the HIMS to measure the spectral reflectance of LAA from samples originating from three different environments (South Cascade, Colorado Rockies, and Iceland). South Cascade LAA include red and bright minerals, and black carbon, and highly absorptive minerals. Colorado Rockies LAA included red and white minerals with some black carbon, and were most identifiable by the abundance of iron oxides. Iceland LAA include ash that has mostly low reflectance, but particle size and ROI selection have influenced reflectance data. By analyzing hyperspectral data in three separate environments, it is evident that there are large differences in the optical properties of LAA at the particle scale. This large range of variability confirms that generic optical properties should not be used to determine the contribution of LAA to albedo reductions and melt.

Available for download on Wednesday, January 10, 2024

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