DOT/FAA/TC-14/31 The High Ice Water Content Study Federal Aviation Administration William J. Hughes Technical Center of Deep Convective Clouds: Aviation Research Division Atlantic City International Airport Report on Science and Technical New Jersey 08405 Plan July 2016 Final Report This document is available to the U.S. public through the National Technical Information Services (NTIS), Springfield, Virginia 22161. This document is also available from the Federal Aviation Administration William J. Hughes Technical Center at actlibrary.tc.faa.gov. U.S. Department of Transportation Federal Aviation Administration NOTICE This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the contents or use thereof. The U.S. Government does not endorse products or manufacturers. Trade or manufacturers’ names appear herein solely because they are considered essential to the objective of this report. The findings and conclusions in this report are those of the author(s) and do not necessarily represent the views of the funding agency. This document does not constitute FAA policy. Consult the FAA sponsoring organization listed on the Technical Documentation page as to its use. This report is available at the Federal Aviation Administration William J. Hughes Technical Center’s Full-Text Technical Reports page: actlibrary.tc.faa.gov in Adobe Acrobat portable document format (PDF). Technical Report Documentation Page 1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. DOT/FAA/TC-14/31 4. Title and Subtitle 5. Report Date THE HIGH ICE WATER CONTENT STUDY OF DEEP CONVECTIVE July 2016 CLOUDS: REPORT ON SCIENCE AND TECHNICAL PLAN 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No. Strapp, J.W., A. Korolev, T. Ratvasky, R. Potts, A. Protat, P. May, A. Ackerman, A. Fridlind, P. Minnis, J. Haggerty, J. T. Riley, Lyle E. Lilie, and G.A. Isaac 9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) Met Analytics Inc. 88 Whispering Pine Trail 11. Contract or Grant No. Aurora, ON, Canada L4G4Y1 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered U.S. Department of Transportation Final Report Federal Aviation Administration William J. Hughes Technical Center 14. Sponsoring Agency Code Aviation Research Division ANE 111 Atlantic City International Airport, NJ 08405 15. Supplementary Notes The Federal Aviation Administration William J. Hughes Aviation Research Division COR was James Riley. 16. Abstract This report describes a collaborative research project to collect atmospheric data to support engineering issues related to the failure of commercial aircraft jet engines in convective clouds and a variety of scientific issues related to the microphysical properties and structure of deep convective clouds. The aviation sector has compiled information on more than 100 weatr he -related engine power-loss events and concluded that they are due to flight through areas of high ice water content (HIWC) associated with deep convective clouds. Flight into high ice concentrations has also resulted in failures of air data probes, most notably aircraft pitot probes. As a result, an industry-led working group, the Engine Harmonization Working Group (EHWG), recommended the collection of an in situ data set to characterize the microphysical properties of these clouds, to be used to provide guidance to manufacturers and to substantiate the new Title 14 Code of Federal Regulations Part 33 Appendix D engine icing certification envelope for HIWC ice crystal conditions. This report provides background information and recommendations on how to conduct flight test operations for these aviation objectives. The objectives of the data collection and the design of the flight experiment were determined during numerous meetings of the EHWG and are consistent with its technical plan. Measurements will focus on the characterization of HIWC regions and the provision of 99th percentile total water content statistics and ice crystal characteristic size as a function of distance scale. These measurements will provide the first extensive modern data set of in situ measurements of the updraft areas of tropical oceanic deep convection and stratiform regions of more vigorous tropical continental convection that can be safely penetrated and will be a unique resource for the industry and science communities. Data will be used by the science community to improve knowledge on basic cloud microphysical processes and numerical cloud modeling and to develop better algorithms for ground- and space-based remote sensors in active convective cells. In addition, the measurements will support the development of pilot’s radar and nowcasting tools for the aviation sector to help in forecasting and avoidance of these hazardous cloud regions. 17. Key Words 18. Distribution Statement This document is available to the U.S. public through the Ice crystal icing, Jet-engine icing, Appendix D, NPRM 10-10 National Technical Information Service (NTIS), Springfield, Virginia 22161. This document is also available from the Federal Aviation Administration William J. Hughes Technical Center at actlibrary.tc.faa.gov. 19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price 105 Unclassified Unclassified Form DOT F 1700.7 (8-72) Reproduction of completed page authorized TABLE OF CONTENTS Page EXECUTIVE SUMMARY xi 1. INTRODUCTION 1 1.1 Jet-engine Powerloss in Deep Convective Clouds 1 1.2 Review of Hypothesis on the Meteorological Conditions that Cause Engine Power-Loss Events 2 1.2.1 Hypotheses on the Location of HIWC Regions 7 1.3 Motivation for Meteorological Investigations in aN HIWC Study 10 2. TECHNICAL (AVIATION) OBJECTIVES OF THE FLIGHT TEST PROGRAM TO SUPPORT THE JET ENGINE ICING ISSUE 11 2.1 Background 11 2.2 Overview of Engine (Aviation) Objectives 13 2.3 Objective E1: Characterization of the HIWC Environment 13 2.3.1 TWC Statistics for the EIWG 13 2.3.2 Estimates of Hydrometeor Characteristic Size for the EIWG 15 2.3.3 Cloud Resolving Model Simulations to Integrate Measurements and Theory 16 2.3.4 Linking Characteristics of Sampled Clouds to the Engine-Event Database 17 2.4 Objective E2: Flight-Deck Recognition of the HIWC Environment 18 2.4.1 Visual/Aural Signatures of HIWC 18 2.4.2 Radar Reflectivity in HIWC Regions 19 2.4.3 Onboard Sensors to Detect the Presence of HIWC on Commercial Aircraft 21 2.5 Objective E3: Development of Tools to Nowcast the HIWC Environment 21 3. SCIENCE OBJECTIVES 23 3.1 Overview of Science Objectives 23 3.2 Objective S1: Characterization of the Microphysical and Thermodynamic Properties of Vertically Developing Cells of Deep Convective Clouds 25 3.3 Objective S2: Small Ice Particle Formation in Deep Convective Clouds and Importance of Small Ice Crystals in Bulk Microphysical Properties 30 iii 3.4 Objective S3: Temporal and Spatial Evolution of the Mixed Phase in Deep Convective Clouds 33 4. OBJECTIVE S4: VALIDATION OF GROUND-BASED, REMOTELY SENSED MICROPHYSICAL PROPERTIES OF DEEP CONVECTION AND ASSOCIATED CLOUD SYSTEMS 35 4.1 Objective S5: Validation of Satellite Remote Sensing of Cloud Properties and HIWC Regions in Deep Convection 38 4.2 Objective S6: Improvement of Simulation of Deep Convection Using CRMs 41 5. MEASUREMENTS TO SUPPORT TECHNICAL AND SCIENCE OBJECTIVES 42 5.1 Research Aircraft Measurements 42 5.1.1 Basic Aircraft Requirements 42 5.1.2 Aircraft Accommodation of Instrumentation 44 5.1.3 List of Instrumentation 44 5.1.4 Instrumentation Development and Modifications for HIWC 47 5.2 Ground Observational Network Requirements 47 5.2.1 Ground-Based Radar 47 5.2.2 Other Ground-Based Data 48 5.2.3 Lightning Network Data 48 5.3 Meteorological Satellite Requirements 48 6. FLIGHT CAMPAIGN LOCATIONS 49 6.1 The Darwin Location 51 7. AIRBORNE MEASUREMENT STRATEGY AND FLIGHT PLANS 54 7.1 Types of Convection and Distribution of Flights 54 7.2 Flight Sampling Strategies 59 7.2.1 Idealized Flight Plans: Small Convective Systems Over Water 59 7.2.2 Idealized Flight Plans: MCS Over Water (Less Vigorous) 61 7.2.3 Idealized Flight Plans: MCS Over Land (More Vigorous) 64 7.2.4 Idealized Flight Plans: Tropical Storms 66 7.2.5 Optimizing Flight Methodologies for Non-Vigorous Clouds 67 7.2.6 Sampling Statistics: Small Convective Systems Over Water; MCS Over Water and Land; and Tropical Storms 69 7.2.7 Temperatures (Altitudes) of Flight Transects 70 iv 7.2.8 Additional Idealized Flight Plans: Isolated and Multi-Cell Continental Convection 70 7.2.9 Additional Flight Plans Variations to Support HIWC Science Objectives 71 8. FLIGHT PROGRAM OPPORTUNITIES 72 8.1 Recent industry flight-test programs 72 8.2 The HAIC-HIWC Darwin 2014 flight campaign 73 8.3 Other future campaigns 73 8.4 Measurements from commercial aircraft 74 9. HIWC PROJECT PARTNERS 74 10. REFERENCES 76 APPENDIX A—EFFORTS UNDERTAKEN BY THE HIGH ICE WATER CONTENT TEAM TO CHARACTERIZE AND IMPROVE INSTRUMENT PERFORMANCE FOR THE HIGH ICE WATER CONTENT ENVIRONMENT A-1 v LIST OF FIGURES Figure Page 1 Simplified cross section of a deep convective cloud, from the Australian Storm Spotter’s Guide 4 2 Median VPRR from convective cells in 41 tropical oceanic, 44 tropical continental, and 57 mid-latitude continental MCS events studied 7 3 Pictures of overshooting tops 9 4 NOAA-15 AVHRR visible and IR imagery from an overpass on June 19, 2001 show the structure of the overshooting tops and cloud-top