PARTITIONING THE CONTRIBUTION OF LIGHT ABSORBING AEROSOLS TO SNOW AND GLACIER MELT USING A NOVEL HYPERSPECTRAL MICROSCOPY METHOD

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, dust and organics onto snow and glacier surfaces can be an even larger driver of melt in some regions. Attempts to partition the relative contribution of different types of LAA to snow and glacier melt based on LAA abundances are limited by uncertainties in the LAA optical properties. The objective of this research is to optically characterize LAA from different regions using a recently developed Hyperspectral Imaging Microscope Spectrometer (HIMS) method. HIMS combines optical microscopy and high-resolution hyperspectral imaging technology to provide hyperspectral images of LAA at 138 nm² pixel resolution. Using HIMS different LAA can be characterized by morphology, color, and reflectance at the submicron scale. The LAA samples used for optical characterization were sourced from snow and glaciers from: Iceland; the Peruvian Andes; Juneau Icefield, Alaska; Colorado Rockies; Central Tibetan Plateau; and the Washington Cascades. These samples encompass a wide range of environments with differences in LAA relative abundances and LAA particle reflectance. We present the results from this research, including an assessment of regional differences in LAA contributions to snow and glacier melt due to regional variations in LAA optical properties and abundances in different environmental settings.