Quantification of the Effects of Shattering on Airborne Ice Particle Measurements

Abstract

Ice particle shattering poses a serious problem to the airborne characterization of ice cloud microstructure. Shattered ice fragments may contaminate particle measurements, resulting in artificially high concentrations of small ice. The ubiquitous observation of small ice particles has been debated over the last three decades. The present work is focused on the study of the effect of shattering based on the results of the Airborne Icing Instrumentation Evaluation (AIIE) experiment flight campaign. Quantitative characterization of the shattering effect was studied by comparing measurements from pairs of identical probes, one modified to mitigate shattering using tips designed for this study (K-tips) and the other in the standard manufacturer's configuration. The study focused on three probes: the forward scattering spectrometer probe (FSSP), the optical array probe (OAP-2DC), and the cloud imaging probe (CIP). It has been shown that the overestimation errors of the number concentration in size distributions measured by 2D probes increase with decreasing size, mainly affecting particles smaller than approximately 500 mm. It was found that shattering artifacts may increase measured particle number concentration by 1 to 2 orders of magnitude. However, the associated increase of the extinction coefficient and ice water content derived from 2D data is estimated at only 20%-30%. Existing antishattering algorithms alone are incapable of filtering out all shattering artifacts from OAP-2DC and CIP measurements. FSSP measurements can be completely dominated by shattering artifacts, and it is not recommended to use this instrument for measurements in ice clouds, except in special circumstances. Because of the large impact of shattering on ice measurements, the historical data collected by FSSP and OAP-2DC should be reexamined by the cloud physics community.Corresponding author address: Alexei Korolev, Cloud Physics and Severe Weather Section, Environment Canada, 4905 Dufferin St.,

Ice crystal number concentration estimates from lidar-radar satellite remote sensing. Part 1: Method and evaluation

“…D < 100 µm), which highly contribute to N i . This implies that possible phenomena of ice crystal shattering on the probe tips and inlets (Korolev et al, 2011(Korolev et al, , 2013) must be accounted for to a reasonable extent, through combined specific instrumental design and post-processing (Field et al, 2006;Korolev and Field, 2015). Jensen et al, 2015).…”

Further evidence for superterminal raindrops

“…Hauser et al, 1984;Hosking and Stow, 1991;Kruger and Krajewski, 2002]. Gardiner and Hallett, 1985;Field et al, 2006;Korolev et al, 2013]. One could argue that the analogue of shattering for rain detection would be a type of splashing and suggests that perhaps the measured superterminal drops might still be the result of an instrumental artifact.…”

A statistical comparison of cirrus particle size distributions measured using the 2-D stereo probe during the TC&lt;sup&gt;4&lt;/sup&gt;, SPARTICUS, and MACPEX flight campaigns with historical cirrus datasets

“…Results from several flight legs made during three field campaigns where this was done are described in three recent papers: Korolev et al (2013b), , and . Probes built for several particle size ranges were examined, but those of interest here are the 2D-S and the older 2DC.…”

“…The opposite is true for the 2DC. This is attributed to the 2D-S's larger sample volume; to its improvements in resolution and electronic time response over the 2DC; and to its 256 photodiode elements (Jensen et al, 2009;Lawson, 2011;Brenguier et al, 2013), which allow it to size particles smaller than 100 µm and to measure particle inter-arrival times more accurately (Lawson et al, 2010;Korolev et al, 2013b;Brenguier et al, 2013).…”

“…Thus Korolev et al (2013b) posit that bulk quantities computed from higher-order PSD moments -such as shortwave extinction coefficient, IWC, and radar reflectivity -are likely to compare much better between the 2D-S and the 2DC than is N T (see also Heymsfield et al, 2017).…”