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Anti-Shatter Tips for Cloud Imaging Probe (CIP), Cloud Combination Probe (CCP) or Cloud, Aerosol, and Precipitation Probe (CAPS)
Print Version
Sample integrity is a fundamental requirement for accurate measurement of aerosols and precipitation in clouds. Recent work by
Korolev and others
demonstrates that droplets and ice crystals hitting the DMT Cloud Imaging Probe (CIP) can leave unwanted artifacts in the sample space, but that this problem can be remedied by outfitting the instrument with specially designed tips.
Atmospheric ice and liquid particles that strike a solid surface on an aircraft or measurement probe will shatter, bounce, and/or splash, creating many small particles. When this occurs forward of the probe sample area, the fragments can cause errors in the measured particle number and size distribution. The design principle behind the Korolev Tips, pictured below, insures that trajectories of the modified particles do not intersect the probe sample area and cause a sampling artifact.
Original CIP Design
The original tip design used cylinders at the ends of the probe arms and "wetless" windows. These cylinders and the "wetless" windows have the potential for creating fragments which can have trajectories into the sample area.
Modified "Korolev-Tip" Design
The modified “Korolev-tip” design does not prevent shattering and splashing from occurring, but the design deflects shattered fragments away from the sample volume. This tip modification further reduces the artifact by eliminating probe protrusions upstream from the sample area.
Flight Testing of Tip Design
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Flight testing of different tip designs was carried out by Environment Canada in the vicinity of Ottawa during 2009 by employing side by side mounting of the standard and modified tip designs (left).
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The CIP images from the left panel below are from the unmodified tips. These images clearly show the small particle artifact due to shattering/splashing as contrasted with the modified design shown on the right side panel. (The vertical lines are particle separators, so vertical lines grouped closely together indicate small particles or fragments.)
The data plot below gives the time trace of number concentration for the standard tips and modified tips. The altitude and ambient temperature are shown for reference.
The chart below shows an associated size distribution from a selected flight through an ice cloud.
Selected Bibliography
“Small ice particles in tropospheric clouds: fact or artifact?, Airborne Icing Instrumentation Evaluation Experiment,” A. V. Korolev, E. F. Emery, J. W. Strapp, S. G. Cober, G. A. Isaac and M. Wasey, BAMS, submitted May 2010.
“The effect of ice bouncing and shattering on the performance of airborne cloud microphysical instrumentation," A. Korolev, G. McFarquhar, P. Lawson, J-F Gayet, M. Kraemer, A Heymsfield, D. Rogers, C. Twohy, and O. Stetzer, AMS conference proceedings from Portland, Oregon, July 2010.
“Particle impact and breakup in aircraft measurements,” Vidaurre and J. Hallet, J. Atmos. Oceanic Technol., 26, 972-9 83, 2009, link.
“Shattering and particle interarrival times measured by optical array probes in ice clouds,” P. R. Field, A. J. Heymsfield, and A. Bansemer, J, Atmos Oceanic Technol., 23, 1357-1370, 2006, link.
Patent application, 2009: “Probe tips for airborne instruments used to measure cloud microphysical parameters,” Canadian patent application #2660753, United States patent application #12/415,314.
Specifications
| Sample Volume Length |
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Two separate arm lengths available to optimize measurement under different cloud optical densities:
• Short sample volume length (4 cm) best for optically dense clouds
• Long sample volume length (7 cm) best for optically thin clouds
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| Anti-Ice Heaters |
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Heaters embedded in tips to avoid ice-build-up
Specify voltage when ordering: 115 VAC or 28VDC
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| Construction Material |
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Tips constructed of aluminum with titanium nitride (TiN) coating for surface protection and electrical conductivity
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| Windows |
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• Prevent water and moisture from entering the probe arms
• Are removable for easy cleaning
• Contain water removal features that direct water away from the windows
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| Tip Covers |
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Covers are included for user safety and to protect tips from damage; remove before use
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Specifications are subject to change without notice.
How to Order
Korolev Tips can be retrofitted to existing stand-alone Cloud Imaging Probes (CIP) and to the CIP section of a Cloud Combination Probe (CCP) or a Cloud, Aerosol, and Precipitation Probe (CAPS). The service includes a standard cleaning and complete probe calibration with minor repairs to insure a properly functioning probe after retrofit.
Korolev Tips are available as an option when ordering a Cloud Imaging Probe (CIP), Cloud Combination Probe (CCP) or Cloud, Aerosol, and Precipitation Probe (CAPS).
Contact DMT for pricing and to schedule a retrofit: +1.303.440.5576,
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Acknowledgments
DMT has secured the license to manufacture and distribute this patented design from Environment Canada and has worked closely with A. Korolev (Environment Canada) to adapt the patented tip design to meet production and servicing requirements.
High-Speed Photo Footage
Below is a high-speed image of a standard CIP tip during a wind tunnel run. Note the shattered droplets enter into the sample area creating measurement artifacts.
Below is a high-speed image of a modified CIP tip during a wind tunnel run. Note the lack of artifact particles entering the sample area.
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