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ARS Home » Pacific West Area » Boise, Idaho » Watershed Management Research » Research » Publications at this Location » Publication #310655

Research Project: Understanding Snow and Hydrologic Processes in Mountainous Terrain with a Changing Climate

Location: Watershed Management Research

Title: Modeling temperature and humidity profiles within forest canopies

Author
item Flerchinger, Gerald
item Reba, Michele
item Link, Timothy - University Of Idaho
item Marks, Danny - Danny

Submitted to: Agricultural and Forest Meteorology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/18/2015
Publication Date: 8/6/2015
Citation: Flerchinger, G.N., Reba, M.L., Link, T.E., Marks, D.G. 2015. Modeling temperature and humidity profiles within forest canopies. Agricultural and Forest Meteorology. 213:251-262.

Interpretive Summary: Understanding the role of ecosystems in modulating energy, water and carbon fluxes is critical to quantifying the variability in energy, carbon, and water balances across landscapes. These balances are subject to change with vegetation changes resulting from management, climate change or vegetation succession. Refinements to a plant canopy model were tested for three diverse forest canopies. Good agreement between measured and modeled temperature and humidity profiles within the forest canopy suggest that the model can be reliably used to simulate vegetation influence on energy, water and carbon fluxes from diverse ecosystems. Scientists can capitalize upon these results to better describe and model these ecosystems and the influence of landscape changes.

Technical Abstract: Physically-based models are a powerful tool to help understand interactions of vegetation, atmospheric dynamics, and hydrology, and to test hypotheses regarding the effects of land cover, management, hydrometeorology, and climate variability on ecosystem processes. The purpose of this paper is to further refine the modifications to a multi-layer plant canopy model and to evaluate it for simulating temperature and water vapor within three diverse forest canopies: a 4.5-m tall aspen thicket, a 15-m tall aspen canopy, and a 60-m tall Douglas fir canopy. Root mean square deviation (RMSD) between simulated and observed temperature ranged from 0.1°C for the top of the 15-m aspen canopy during the winter to 1.5°C for the bottom of the 4.5-m aspen thicket during the summer period. RMSD for vapor pressure ranged from 0.002 kPa for the top of the 15-m aspen canopy during winter to 0.120 kPa for the bottom of the 15-m aspen canopy during the summer. At each site, the model performed best near the top of canopy where the air was well mixed and gradients between it the meteorological conditions above the canopy used to drive the model were minimal. RMSD tended to increase with depth in the canopy as the distance from the driving meteorological observations increased. RMSD also tended to be higher for the summer periods when there was much more heat and vapor added to the canopy space due to solar warming and transpiration.