Night-time airflow in a forest canopy near a mountain crest

0348522 - ÚFA 2011 RIV NL eng J - Journal Article
Sedlák, Pavel - Aubinet, M. - Heinesch, B. - Janouš, Dalibor - Pavelka, Marian - Potužníková, Kateřina - Yernaux, M.
Night-time airflow in a forest canopy near a mountain crest.
Agricultural and Forest Meteorology. Roč. 150, č. 5 (2010), s. 736-744. ISSN 0168-1923. E-ISSN 1873-2240
R&D Projects: GA AV ČR IAA300420803; GA AV ČR KJB3087301
Grant - others:CarboEurope Integrated Project(XE) GOCE-CT-2003-505572
Institutional research plan: CEZ:AV0Z30420517; CEZ:AV0Z60870520
Keywords : Spruce forest * Canopy layer * Slope * Drainage flow * Wind profile
Subject RIV: DG - Athmosphere Sciences, Meteorology
Impact factor: 3.228, year: 2010

Night-time airflow within a deep and dense canopy near the top of a mountain ridge is investigated based on measurements at Bily Kriz, Czech Republic. A decoupled two-layer structure of canopy flow typically develops at night. While the above-canopy flow is most frequently an upslope-directed larger-scale flow over the ridge, the lower-canopy flow is downslope. However, the lower-canopy flow can be forced upslope when the wind speed above the canopy exceeds a well-defined limit. Less frequently, on the lee slope to the larger-scale flow, both the above-canopy and the lower-canopy flow are usually downslope, although a flow reversal in the lower canopy is also observed, accompanied with a large shear stress (friction velocity) above the canopy. We introduce a simple diagnostic model, which gives realistic values of the downslope or upslope direction and speed of the lower-canopy flow that agree well with the measurements.
Permanent Link: http://hdl.handle.net/11104/0189042