Authors:  Sean P. Burns and Peter D. Blanken

Title: Characteristics of Airflow and Turbulence Just-Above and Within
a Subalpine Forest in Complex Terrain.

Winds at the the long-term Niwot Ridge Subalpine Forest AmeriFlux
tower (US-NR1) have typically been measured at 3-4 levels between the
primary flux-measurement level (21.5 m) and the ground.  In order to
enhance the vertical resolution of the wind profile, seven CSAT3 sonic
anemometers were added to the US-NR1 tower in Fall of 2014 and
operated for a full year.  The US-NR1 site is located in complex
mountainous terrain approximately 8 km east of the Continental Divide
below Niwot Ridge, Colorado.  The topography at the site has a slope
angle that ranges from 4-7 degrees with much steeper terrain within
several miles of the tower.  The mixed-conifer subalpine forest
surrounding the tower has a leaf-area index (LAI) of approximately
3.8-4.2.  We present several aspects of air flow in complex terrain
related to: (1) how a forest and stability affect the vertical profile
of wind speed, wind direction, and turbulence at the site, and (2) the
general characteristics of the downslope nocturnal drainage flow.