Slope flows in the presence of vegetation during Perdigão

In the spring of 2017, the Perdigão campaign instrumented a unique, forested, parallel ridge mountain in Perdigão, Portugal in unprecedented spatial and temporal resolution using tower mounted sensors and a network of Doppler LiDARs. Of particular interest to Perdigão were complex terrain processes that occur under varied synoptic forcing. Under weak synoptic forcing, as recently observed during the MATERHORN program, a diurnal pattern of thermal circulations consisting of up/down slope and up/down valley flows are the dominant flow pattern. At MATERHORN, the mountain was much more idealized as it was mostly void of vegetation whereas at Perdigão, the mountain was densely forested. To investigate the influence of the canopy on the slope flows, a slope transect was instrumented with a series of 30 m towers, placed less than 100m apart. To capture the flow above the canopy, synchronized dual Doppler LiDARs extended the tower measurements vertically with virtual tower scans to several hundred meters above. Quiescent periods of data were analyzed to investigate the impact of the canopy compared to MATERHORN observations of Granite Mountain, on slope flow development, boundary layer growth, turbulence, surface fluxes, and surface energy budgets.