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| Titel |
Effects of ice particles shattering on the 2D-S probe |
| VerfasserIn |
R. P. Lawson |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 4, no. 7 ; Nr. 4, no. 7 (2011-07-05), S.1361-1381 |
| Datensatznummer |
250002050
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| Publikation (Nr.) |
 copernicus.org/amt-4-1361-2011.pdf |
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| Zusammenfassung |
| Recently, considerable attention has been focused on the issue of large ice
particles shattering on the inlets and tips of cloud particle probes, which
produces copious ice particles that can be mistakenly measured as real ice
particles. Currently two approaches are being used to mitigate the problem: (1) Based on recent high-speed video in icing tunnels, probe tips have been
designed that reduce the number of shattered particles that reach the probe
sample volume, and (2) Post processing techniques such as image processing
and using the arrival time of each individual particle. This paper focuses
on exposing suspected errors in measurements of ice particle size
distributions due to shattering, and evaluation of the two techniques used
to reduce the errors. Data from 2D-S probes constitute the primary source of
the investigation, however, when available comparisons with 2D-C and CIP
measurements are also included. Korolev et al. (2010b) report results from a
recent field campaign (AIIE) and conclude that modified probe tips are more
effective than an arrival time algorithm when applied to 2D-C and CIP
measurements. Analysis of 2D-S data from the AIIE and SPARTICUS field
campaigns shows that modified probe tips significantly reduce the number of
shattered particles, but that a particle arrival time algorithm is more
effective than the probe tips designed to reduce shattering. A large dataset
of 2D-S measurements with and without modified probe tips was not available
from the AIEE and SPARTICUS field campaigns. Instead, measurements in
regions with large ice particles are presented to show that shattering on
the 2D-S with modified probe tips produces large quantities of small
particles that are likely produced by shattering. Also, when an arrival time
algorithm is applied to the 2D-S data, the results show that it is more
effective than the modified probe tips in reducing the number of small
(shattered) particles. Recent results from SPARTICUS and MACPEX show that
2D-S ice particle concentration measurements are more consistent with
physical arguments and numerical simulations than measurements with older
cloud probes from previous field campaigns. The analysis techniques in this
paper can also be used to estimate an upper bound for the effects of
shattering. For example, the additional spurious concentration of small ice
particles can be measured as a function of the mass concentration of large
ice particles. The analysis provides estimates of upper bounds on the
concentration of natural ice, and on the remaining concentration of
shattered ice particles after application of the post-processing techniques.
However, a comprehensive investigation of shattering is required to quantify
effects that arise from the multiple degrees of freedom associated with this
process, including different cloud environments, probe geometries, airspeed,
angle of attack, particle size and type. |
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