OPERATIONAL LIGHTNING FORECASTING TECHNIQUE DEVELOPMENT AND TESTING UTILIZING C-BAND DUAL-POLARIMETRIC RADAR by CRYSTAL J. WOODARD A THESIS Submitted in partial fulfillment of the requirements for the degree of Master of Science in The Department of Atmospheric Science to The School of Graduate Studies of The University of Alabama in Huntsville HUNTSVILLE, ALABAMA 2011 UMI Number: 1507429 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent on the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. UMI 1507429 Copyright 2012 by ProQuest LLC. All rights reserved. This edition of the work is protected against unauthorized copying under Title 17, United States Code. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, MI 48106 - 1346 ACKNOWLEDGMENTS I would first and foremost like to thank my advisor, Dr. Larry Carey, for his time and patience in assisting the development of my education and research. I would like to extend words of gratitude to my committee members, Dr. Kevin Knupp and Dr. Walt Petersen. I would also like to acknowledge the assistance of the faculty and staff of the Atmospheric Science Department of UAHunstville and my peers, especially Chris and Elise Schultz, Sandy LaCorte, Mariana Felix, Whitney Guerin and Dennis Buechler. I would not be on this track without the support of my family and extended family, David and Darlene Boiko and Jim and Dianne Stewart, who have supported and encouraged me to strive to achieve this goal. I am also most gracious for the support and of the Military Officers’ Association of America, National Oceanic and Atmospheric Administration (NOAA) Collaborative Science, Technology, and Applied Research Program (CSTAR), and National Aeronautics and Space Administration (NASA) Marshall Space Flight Center (MSFC) during my educational endeavors. v TABLE OF CONTENTS Page List of Figures .................................................................................................................viii List of Tables ................................................................................................................. xiii Chapter I INTRODUCTION ....................................................................................................... 1 II BACKGROUND ......................................................................................................... 4 2.1 Convective Development ...................................................................................... 6 2.2 Charging ............................................................................................................... 13 2.3 Flash ..................................................................................................................... 20 2.4 Previous Radar-based First Flash Forecasting and Observations ........................ 25 III DATA AND METHODOLOGY ............................................................................... 31 3.1 Instruments .......................................................................................................... 33 3.1.1 Radar: ARMOR ....................................................................................... 33 3.1.2 NALMA and NLDN ................................................................................ 46 3.2 Cell Selection ....................................................................................................... 47 3.3 Atmospheric Sounding ......................................................................................... 51 3.4 Radar Data Analysis Methodology ...................................................................... 51 3.4.1 Zh and ZDR Calibration ............................................................................. 51 3.4.2 Attenuation Correction ............................................................................. 52 3.4.3 PID ........................................................................................................... 54 3.5 Test Algorithms ................................................................................................... 60 vi 3.6 Skill Scores .......................................................................................................... 65 IV RESULTS AND DISCUSSION ................................................................................ 70 4.1 Thunderstorm Forecasting .................................................................................. 75 4.1.1 The bench mark ........................................................................................ 75 4.1.2 Basic radar reflectivity, Zh ....................................................................... 76 4.1.3 ZDR column .............................................................................................. 80 4.1.4 PID ........................................................................................................... 83 4.1.5 Comparison of thunderstorm forecasting techniques .............................. 87 4.2 Cloud-to-Ground Forecasting .............................................................................. 88 4.2.1 The bench mark ........................................................................................ 88 4.2.2 Basic radar reflectivity, Zh ....................................................................... 90 4.2.3 ZDR column .............................................................................................. 93 4.2.4 PID ........................................................................................................... 97 4.2.5 Optimum CG forecasting technique ........................................................ 99 4.3 Comparison of CG and Thunderstorm Forecasting ........................................... 102 V SUMMARY, CONCLUSIONS, AND FUTURE WORK ...................................... 104 5.1 Summary of Objectives and Methods ............................................................... 104 5.2 Results Summary, Conclusions and Future Work ............................................ 106 APPENDIX: Lead Time Histograms, Mean, Median and Mode ................................. 112 REFERENCES .............................................................................................................. 120 vii LIST OF FIGURES Figure Page 2.1 Diagram of Benjamin Franklin’s atmospheric electricity warning system. A bell and ball warning system for the detection of electrical fields associated with atmospheric electricity of thunderstorms. .............................................................. 5 2.2 An idealized depiction of the three stages in the life cycle of an ordinary single cellular thunderstorm, (a) cumulus or growth stage, (b) mature stage and (c) dissipating stage. The vectors indicate the strength and general direction of motion in the storm cell. An idealized altitude and temperature profile of the storm is indicated on the Y-axis. ............................................................................ 6 2.3 Radar reflectivity cross section of a developing convective cell. The thermal levels for -10, -15, and -20°C level are indicated. a) Radar cross section of a convective cell in the growth phase. b) Cross section of a cell nearing the mature phase. c) Cross section of a mature cell with a precipitation core and downdraft as indicated by high reflectivity values. d) Cross section after the decent of the precipitation core. ................................................................................................ 10 2.4 An idealized profile of a mature convective cell indicating the bulk precipitation phases at generalized thermal levels. At thermal temperatures above freezing, precipitation is ideally liquid only. In regions below freezing temperatures, water and ice exists together in the mixed phase region. All water phase hydrometeors freeze at temperatures below -40°C, thus this region is dominated by ice forms only. ..................................................................................................................... 12 2.5 Example of negative non-inductive charging mechanism between two hydrometeors, such as graupel and ice crystal. The two particles collide momentarily exchanging a charge, then separate carrying opposite charges. ..... 15 2.6 The idealized tripole structure of a mature thunderstorm consists of a lower positive charge existing at levels below -10°C, a main negative charge extending from approximately -10 to -20°C and the upper region of the cloud hosts the upper main positive charge which extends from -20°C and above. The region roughly between -10 and -20°C is the approximate location of the main processes of charging. .......................................................................................................... 18 2.7 A more accurate idealization of the charge structure of a thunderstorm. The charge accumulations in a thunderstorm are not perfectly vertically separated. This image though still an idealization of the charge centers depicts the distribution of charge centers throughout the convective cell. ............................ 19 viii 2.8 Positive corona is a positively charged point in an enhanced electric field that attracts positive ions which initiates an electron avalanche. This is the beginning of a streamer leading to the development of a flash of lightning.