The Physical Representation of Bare Ice Albedo in Radiative Transfer Models and the Implications on Greenland Ice Sheet Albedo and Surface Mass Balance
Accurate modeling of cryospheric surface albedo is essential for our understanding of climate change as snow and ice surfaces regulate the global radiative energy budget and sea level through their albedo and mass balance. Although significant progress has been made using physical principles to repr...
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| Other Authors: | , , , , , |
| Format: | Thesis |
| Language: | English |
| Published: |
2023
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| Subjects: | |
| Online Access: | https://hdl.handle.net/2027.42/193485 https://doi.org/10.7302/23130 |
| Summary: | Accurate modeling of cryospheric surface albedo is essential for our understanding of climate change as snow and ice surfaces regulate the global radiative energy budget and sea level through their albedo and mass balance. Although significant progress has been made using physical principles to represent the dynamic albedo of snow, models of land ice albedo tend to be heavily parameterized and not explicitly connected with physical properties that govern albedo, such as the number and size of air bubbles, specific surface area, and presence of abiotic and biotic light absorbing constituents (LACs). The lack of physically based and computationally efficient ice albedo models has led to unrealistic bare ice albedo representations in Earth System Models (ESMs). For example, many ESMs prescribe a constant albedo over ice surfaces. However, it is increasingly important that ESMs capture the spatially, temporally, and spectrally varying ice albedo as polar temperatures are rapidly increasing, and more bare ice is being exposed. The Greenland Ice Sheet (GrIS) is currently the largest cryospheric contributor to increasing sea levels, and a significant portion of GrIS surface melt is due to dark ice regions along the edge of the ice sheet, where solar absorption is influenced by the ice albedo. The work presented in this thesis (1) improves our ability to simulate bare ice albedo using physical and optical properties of ice surfaces, (2) incorporates those improvements in an ESM to quantify the contribution of exposed bare ice to the GrIS surface mass balance, and (3) quantifies the relative impact of three different LACs on the GrIS ablation zone melt rates. First, I introduce a single column cryospheric radiative transfer model that accurately simulates the albedo of snow and ice using their physical and optical properties (SNICAR-ADv4). SNICAR-ADv4 compares well to in-situ measurements of snow and ice albedo. SNICAR-ADv4 is applied to ice on the GrIS in the Exascale Earth System Model (E3SM) using MODIS observations ... |
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