My thesis investigates the relationship between snow algae and black carbon from forest fire
aerosols. In Chapter One, I discuss the motivation and objectives of this thesis, followed by a
background on the importance of glaciers in Western Canada, processes of glacier surface
darkening, and a review of the ecology of snow algae and forest fire aerosols. In Chapter Two, I
describe and analyze the results from a field experiment conducted on Place Glacier, in which I
fertilized snow with wood ash. I observed no difference in snowmelt from the treatment, and due
to a loss of data from early snowmelt on the last field visit, the wood ash impact on red snow
algae growth was inconclusive. At the beginning of the field experiment, I measured snow
reflectance, which I then converted to instantaneous radiative forcing. The average instantaneous
radiative forcing for the snow algae at Place Glacier on June 3 was 192 ± 12 W m-2 with a
maximum of 274 ± 16 W m-2. This radiative forcing translated to a melt potential of up to 27.8
mm w.e. d-1. In Chapter Three, I use remote sensing data from the Harmonized Landsat Sentinel
(HLS) project and reanalysis products from MERRA-2 and ERA-5 Land to model the
occurrence of red snow algae on glaciers in British Columbia and Alberta for the summer
seasons of 2015 to 2023. I modelled the red snow algae using the random forest regressor and
XGBoost algorithms, and used the permutation feature importance and SHAP to evaluate the
variables’ influence on the model output. The model explained 60% of the variance in the data
and the three most important variables were longitude, black carbon and temperature. These
results suggest that black carbon may promote red snow algae growth. Finally, in Chapter Four I
conclude with the major findings, limitations and recommendations for future research.
