Preprints
https://doi.org/10.5194/amt-2022-87
https://doi.org/10.5194/amt-2022-87
 
19 May 2022
19 May 2022
Status: this preprint is currently under review for the journal AMT.

Technique for comparison of backscatter coefficients derived from in-situ cloud probe measurements with concurrent airborne Lidar

Shawn Wendell Wagner and David James Delene Shawn Wendell Wagner and David James Delene
  • Atmospheric Sciences, University of North Dakota, Grand Forks, 58202, United States of America

Abstract. Jet engine power loss due to ice particle accumulation is a recognized aviation hazard occurring in cloud conditions difficult to forecast or visually recognize. High-altitude cirrus clouds can have ice particle concentrations high enough to be dangerous; therefore, pilots must be informed when aircraft enter such environments. One approach to determining ice particle concentration is an onboard Lidar system. Concurrent Lidar measurements are compared to backscatter coefficients derived from particle size distributions obtained from wing-mounted, in-situ probes during four case studies consisting of sixty-second flight segments at different temperatures; +7 °C and +4 °C for water droplet analysis, -33 °C and -46 °C for ice particle analysis. Backscatter coefficients derived from external cloud probes (ECP) are correlated (0.91) with measurements by an airborne Lidar system known as the Optical Ice Detector (OID). Differences between OID and ECP backscatter coefficients range from less than 1 to over 3 standard deviations uncertainties. The backscatter coefficients are primarily in agreement for liquid clouds and disagreement for the -33 °C and -46 °C cases, with ECP derived backscatter coefficients lower than the OID for three out of the four cases. Measurements over four research flights show that measured total water content is correlated (0.74) with the OID backscatter coefficient, which indicates that the OID is a useful instrument for determining ice particle concentrations over a broad range of environments, including at ice water contents as low as 0.02 g m-3. Additionally, concurrent measurements from cloud imaging probes and an airborne Lidar test system provides improved knowledge of cloud conditions and can help in understanding cloud processes.

Shawn Wendell Wagner and David James Delene

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2022-87', Anonymous Referee #1, 14 Jun 2022
    • AC1: 'Reply on RC1', Shawn Wagner, 20 Jun 2022
  • RC2: 'Comment on amt-2022-87', Anonymous Referee #2, 20 Jun 2022
    • AC2: 'Reply on RC2', Shawn Wagner, 28 Jun 2022
  • RC3: 'Comment on amt-2022-87', Anonymous Referee #3, 27 Jun 2022

Shawn Wendell Wagner and David James Delene

Data sets

Analysis of Concurrent Backscatter Coefficients from In-situ Cloud Probes and Airborne Lidar Shawn Wagner; David Delene https://doi.org/10.31356/data015

Shawn Wendell Wagner and David James Delene

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Short summary
Jet engine power loss due to ice accumulation is a hazard that occurs in high-altitude clouds. A potential tool to inform pilots when entering such clouds is an onboard Lidar system. Lidar measurements are compared to backscatter coefficients derived from wing-mounted probes and are found to be in agreement for liquid clouds but disagreement for ice clouds. Total water content is correlated with the Lidar measurements, indicating it is useful for ice detection in a range of environments.