Revising the representation of snow and radiation-topography interactions in the GFDL Earth System Model
Webinar, National Oceanic and Atmospheric Administration (NOAA) Climate Process Teams, Virtual
Talks and presentations
Quantifying the Global Effects of Light-Absorbing Particles Deposition on Magnitude and Timing of Snow Melt in an Earth System Model
Talk, American Geophysical Union Fall Meeting, San Francisco, California
The deposition of light–absorbing particles (LAPs) over snow covered surfaces leads to a decrease in surface albedo. This effect, by increasing the energy absorbed by the snowpack, also enhances melt and accelerates snow aging, which in turn is responsible for a further decrease in snow albedo. Quantifying both direct and indirect effects of LAPs deposition on snowmelt is important in Earth System Models (ESMs), as these effects can modulate the timing of runoff and can produce relevant feedbacks in a coupled climate model. Here we investigate the magnitude of LAPs deposition effects on snow melt over a set of instrumented sites spanning a wide range of LAP deposition rates, terrain and climate conditions. To this end we employ GLASS, a newly developed snow scheme implemented in the Geophysical Fluid Dynamics Laboratory (GFDL) ESM. GLASS provides a detailed multi-layer description of snow processes, with prognostic prediction of snow optical diameter as well as snow grain shape. The mass balance of each LAP species is explicitly resolved within the multi-layer snowpack, so that their concentration determines snow optical properties together with grain size and shape. The snow model is forced by dry and wet deposition of black carbon, mineral dust and organic carbon obtained offline from a general circulation model (GFDL AM4.0). We evaluate the new model configuration over a set of instrumented sites in Europe and North America, finding that at most sites the effect of LAPs is quite relevant, with an average reduction in number of snow cover days between 5 and 20 days/year depending on the site. For sites in the Western US this effect is primarily due to dust deposition, while we find the role of black and organic carbon more relevant at study sites in the Alps. Finally, we provide a global quantification of the effects of LAPs on the magnitude and timing of snow melt in current climate conditions (1985-2015).
Harnessing high-resolution terrain information in Earth System Models
Conference proceedings talk, ICIMOD, Kathmandu, Nepal, kathmandu, Nepal