Danielle Perrot

Research

Green Lakes Valley, CO (NWT LTER)

I am interested in the interactions between landscapes, climate, and ecology, and how these interactions affect processes governing snow hydrology and water resources. Below are descriptions of my three current projects.  

Snowmelt and the Mountain Pine Beetle

Dead and dying lodgepole pine in Rocky Mountain National Park (CO)

The Mountain Pine Beetle (MPB) has had a profound effect on the health of forests in western North America. Much of the area impacted by the MPB depends on snowmelt for its water. Trees (needle-leaf, in this case) determine the energetics of the sub-canopy and in return mediate how snow will accumulate, and how fast and when it will melt. It follows that a change in canopy structure related to tree-death may induce changes in snowpack processes. Some of my work has focused on trying to model how changing canopy structure would change the energetics of a subcanopy snowpack, and how snowmelt may be affected. 

 

Dust, needles, and snow surface albedo

Ken Peterson applies red lodgepole pine needles and dust to an experimental snowpack plot at a subalpine site (NWT LTER).

The snow surface albedo (reflectivity) determines how much light energy will be absorbed by the snowpack. Darkening the surface of the snowpack by adding contaminants decreases the snow surface albedo and thereby increases the amount of absorbed energy. An increase in snowpack energy results in snowmelt. Currently, wind-deposited dust and needle-litter from MPB-affected trees are two contaminants to the snow surface in subalpine areas that are causing a decrease in snow surface albedo. It is relatively well-understood how these two contaminants influence snow surface albedo separately, but not combined. I am interested in comparing the albedo-reducing effects of dust and needle-litter, studying how they interact in the snowpack to result in combined albedo-reduction, developing a snow albedo model for subalpine areas that incorporates the effects of different contaminants, and incorporating this snow albedo model into a distributed snowmelt model to improve hydrologic forecasting.

Visit our fieldwork blog at http://thealbedoproject.blogspot.com/.

Nitrate and snowmelt in alpine catchments

Alpine stream, Yosemite National Park (CA)

Atmospheric nitrate deposition to alpine areas has been increasing over the last century, and is expected to continue to rise. The addition of nitrate to these nutrient-limited ecosystems can reduce biodiversity of plant communities, acidify streams and lakes, and impact carbon storage. Snowmelt and stream nitrate concentrations have distinct signatures in streamflow. I am interested in whether snowmelt has an effect on when the stream nitrate pulse occurs to examine how different alpine watersheds may hydrochemically react to changes in snowmelt rates and timing under a changing climate. 

 

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