Some atmospheric tracer experiments in complex terrain at LASL: experimental design and data. [Fluorescent particle tracer study] Page: 4 of 39
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Specifications of the particular tracer used in each experiment are given in
data tables that will be discussed below.
B. Release Procedure
Metered quantities of FP tracer material were released using a Metronics
Model 10 Aerosol Generator. The actual amount of tracer released was determined
by pre- and postrelease mass determinations. Release rates were calculated from
this value and the duration of the release. Release rates and amounts varied de-
pending on the experimental situation and details for each experiment are given
in data tables that will follow.
C. Sampling Procedure
Tracer samples were collected using Metronics Rotorod Sampler Model 60 A
and Type H Rotorods. Metal fence posts were installed at each sampling location
and a sampler was attached to each post at approximately one meter dbove the
ground. The collection rods were installed and samplers turned on just prior to
a release and collected as soon after plume passage as was practical. All sam-
plers were operated on 12-volt d.c. battery systems.
The sampler motors used were measured to have a constant angular speed for
supply voltage between 9.3 and 17 volts. To insure proper operation all batter-
ies were checked before each experiment and none was used that measured less
than 11.5 volts under a resistive load.
Figure 2 shows a sampler with a type H rotorod attached. The vertical ro-
torod arms are coated with a blbck silicone adhesive. When the sampler is ener-
gized the rotorod rotates and particles are imparted on the leading edge of the
collection arms. For the particle size range (2-5 um) used in these experiments
this collection system has a 65% efficiency.
The sampling rate, the volume of air swept out by the rotorod per unit
time, is determined as follows (refer to Fig. 3)
Sampling Rate = VWw, (1)
where
V = 2Trdh = volume of a cylindrical shell formed by a rotating
strip of H-type collector rod
d = diameter of rotating cylinder = 12 cm
h = length of one strip = 6 cm
W = width of strip = 0.048 cm
w = angular speed = 2400 50 rpm .3
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Archuleta, J.; Barr, S.; Clements, W.E.; Gedayloo, T. & Wilson, S.K. Some atmospheric tracer experiments in complex terrain at LASL: experimental design and data. [Fluorescent particle tracer study], report, March 1, 1978; New Mexico. (https://digital.library.unt.edu/ark:/67531/metadc1059268/m1/4/: accessed April 24, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.