WMOD00420

• Title: Corrections of Surface Particle Probe Measurements for the Effects of Aspiration
• Date: 8/4/1988
• Weather Modification - Doc Type: Report

AUGUST 1988

TERR Y DESHLER

557

5.0

Winds < t m s-l

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8 3.5

w
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cr 3~0
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@ Winds [-2 m 5-1

* Wnds>2ms"

0.0

0.0

0.5

1.0

1.5

2.0

2.5

3.0

SIZE (mm)

FlG. II. Ratio (aspirated:truckbome) of ice particle concentrations as a function of size for three
windspeed windows: <I, 1-2 and >2 m s.'.

stant air flux through the target appropriate only for
infinitesimal particles.
For discussion of the errors introduced by aspiration,
consider Cm, the ratio of particle concentration at the

target, Ct, to particle concentration in the free stream,
C:

C = Ct = FtAsVs
m Cs FsAtVr'

TABLE 3. Ratios ofIPC by size bin for an aspirated 2D-C to a truckbome 2D-C. The ratios
are also presented for certain windspeed windows.
All measurements Winds 0-1 m S-I Winds 1-2 m s-' Winds> 2 m s-,
Average
winds 1.5 m S-I 0.6 m S-I 1.3 m s-' 3.0 m s-,
Size
interval Number Number Number Number
(mm) Mean u points Mean u points Mean u points Mean u points
0.05-0.1 1.61 0.76 65 1.49 0.54 21 1.82 0.91 24 1.49 0.72 20
0.1-0.2 3.38 1.51 67 3.72 1.11 19 3.66 1.49 27 2.72 1.63 21
0.2-0.3 2.23 1.04 80 2.66 1.09 26 2.24 0.93 33 1.68 0.91 21
0.3-0.4 1.94 0.91 82 2.43 0.93 27 1.86 0.79 34 1.45 0.76 21
0.4-0.5 1.86 0.97 79 2.37 0.91 25 1.78 0.89 33 1.40 0.89 21
0.5-0.6 1.84 0.95 75 2.08 0.84 25 1.99 1.07 30 1.32 0.66 20
0.6-0.8 1.65 0.93 77 1.95 0.87 26 1.81 0.99 31 1.00 0.48 20
0.8-1.0 1.23 0.66 68 1.46 0.74 25 1.26 0.59 28 0.80 0.39 15
1.0-1.5 0.85 0.52 59 1.11 0.66 23 0.77 0.30 23 0.54 0.30 13
1.5-2.0 0.75 0.53 35 0.91 0.63 17 0.53 0.32 13 0.78 0.38 5
2.0-2.5 0.76 0.31 7 0.85 0.28 4 0.46 0.19 2 1.03 I
2.5-3.0 0.55 0.29 2 0.84 I 0.25 I

--~