March 23, 2015 BAO Tower update and tower structure information:

All tower instruments running this morning.
There was a glitch in direction display on NCAR's website starting late last week. Fixed by Steve Oncley.

BAO Tower measurements and structural information.
 Because of the age of the tower (built in ~1976) all we have are blue prints. Below is general information and a link to some pictures.

The tower is a triangular structure 3.05m (10') wide from center leg to center leg.
The orientation of the 3 tower faces are:
334-154 degrees T
274-94 degrees T
214-34 degrees T

The booms point 334 and 154 T (within ~3-5 degrees accuracy)
The distance from outer edge of tower leg to center of sonic path is 4.3m
At each boom level there are instrumentation boxes, power boxes, and elevator control panels that increase the wind blockage. 

Tower legs are 9 1/2" dia at the bottom tapering to 4" at the top.
The lowest 40' above the ground has angle iron cross members. Above this point the cross members are rods.

The west face of the tower has two racks that the elevators ride up/dn on. It is a cog system. The west face also has our cable conduits and hoses for drawing air at 3 levels (22, 100, 300m). This face is parallel to the booms (154/324T) pointing.

The top boom is within a few feet of the very top, so there is almost no structure above it. The top of the tower has more cross members than below and has angle iron cross members again.

There are 6 guy wire connection points on each leg (18 total):
164', 328', 492', 656', 820', and 984'.  Guys are 1 7/16" dia to 2 3/16" dia
At the NE point of the triangular structure there is a ladder running from the bottom to top for emergency evacuation.



Here is where you can see some pictures of the tower:
http://www.esrl.noaa.gov/psd/technology/bao/galler