Black and Bloom

TCD Paper: Bioalbedo model and critique of empirical methods

Our new paper in The Cryosphere presents a model for predicting the spectral albedo reduction resulting from biological growth on snow or ice. The biomass concentration and pigmentation of cells, cell radii, vertical position of the cells in the snow or ice, ice grain radii and inorganic impurity optical properties, mass concentration and vertical distribution can all be prescribed by the user. The model can also be tailored to specific times and locations using measured or modelled incoming solar irradiance. Interstitial water can also be included to better model snow and ice in a state of melt.

Example outputs from BioSNICAR. The legend shows the biomass concentration in a 3mm surface layer of ice (1500 um ice grain radii). The cell radius was 15 um. The pigment concentrations (expressed a % total cell dry mass) were: A) 1.5% chlorophyll a, 10% photoprotective carotenoids; B) 1.5% chlorophyll a, 5% photoprotective carotenoids; C) 1.5% chlorophyll a, 1% photoprotective carotenoids; D) 1.5% chlorophyll a only.

We used the model to support a review of the techniques used to characterize bioalbedo in the field and examine some of the difficulties in linking empirical ground measurements with remote sensing and theoretical work. The paper is written specifically to support those new to spectroscopy in designing experiments to measure biological effects on albedo and to highlight areas of uncertainty.


The paper is available to view here.