WMOD00420

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

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JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY

VOLUME 5

.. Needles. Sheaths, Aggregates. Groupe! - Winds 1.2 m s"

@ Needles, Dendrites, Aggregates, Groupel - Winds 0.8 m S-I

* Needes, Aggregates, Groupel - Winds 1.9 m s"

Graupel. Small rImed particles, Needles - Winds 2.0 m s"

* Needles, Sheaths, Aggregates, Groupel - WindS 0.6 m s"

J
J

0.5

1.0

2.0

3.0

2.5

1.5

SIZE (mml

FiG. 10. Ratio (aspirated:truckborne) of ice particle concentrations as a function of size for the five snowfall events
sampled. The habits observed on each day are listed on the plot in rough order of their predominance.

follow streamlines, whereas larger particles will be rel-
atively unaffected by the converging streamlines. Par-
ticle speed through the target will be similarly affected.
Particles with the least mass will be nearly accelerated

to the airspeed at the target, while larger particles will
be traveling slower. Thus, particle flux through the tar-
get will differ subs~ntially from free-stream part~cle
flux, yet sample vplume is calculated based on a con-

TABLE 2. Ratios of IPC by size bin for an aspirated 2D-C to a truckbome 2D-C. The ratios are presented for each snowfall event.
Needles, sheaths, Needles, dendrites, Needles, aggregates, . Graupel, small rimed Needles, sheaths,
aggregates, graupel aggregates, graupel graupel particles, needles aggregates, graupel
Average
winds 1.2 m S-I 0.8 m S-I 1.9 m S-I 2.0 m S-I 0.6 m S-I
Size
interval Number Number Number Number Number
(mm) Mean (J points Mean (J points Mean (J points Mean (J points Mean (J points
0.05-0.1 1.5 0.6 7 1.5 0.4 11 1.7 1.1 22 1.7 0.6 18 1.5- 0.6 7
0.1-0.2 2.5 0.9 12 4.2 1.2 6 3.4 1.7 22 3.6 1.6 20 3.6 0.6 7
0.2-0.3 2.0 1.1 17 3.3 1.1 12 2.1 1.0 23 2.0 0.9 21 2.1 0.3 7
0.3-0.4 1.7 1.0 18 2.6 0.8 13 1.7 0.8 23 1.9 0.8 21 2.2 1.0 7
0.4-0.5 1.3 0.8 16 2.7 0.8 13 1.7 0.8 23 2.1 1.1 20 1.7 0.7 7
0.5-0.6 1.6 0.6 14 2.4 0.9 13 1.6 0.7 23 2.1 1.3 18 1.6 0.8 7
0.6-0.8 1.3 0.8 16 2.4 0.7 13 1.4 0.6 22 1.9 1.2 19 1.2 0.4 7
0.8-1.0 1.1 0.4 13 1.9 0.7 13 1.0 0.6 20 1.2 0.8 15 0.9 0.2 7
1.0-1.5 0.7 0.3 9 1.5 0.6 13 0.6 0.4 18 0.7 0.3 12 0.7 0.2 7
1.5-2.0 0.6 1 1.1 0.7 11 0.6 0.3 10 0.8 0.5 7 0.5 0.1 6
2.0-2.5 0.7 0.1 2 0.8 0.4 3 1.0 I' 0.5 I
2.5-3.0 0.6 0.3 2