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Convective Cores in Continental and Oceanic Thunderstorms: Strength, Width, And

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Convective Cores in Continental and Oceanic Thunderstorms: Strength, Width, And Convective Cores in Continental and Oceanic Thunderstorms: Strength, Width, and Dynamics THESIS Presented in Partial Fulfillment of the Requirements for the Degree Master of Science in the Graduate School of The Ohio State University By Alexander Michael McCarthy, B.S. Graduate Program in Atmospheric Sciences The Ohio State University 2017 Master's Examination Committee: Jialin Lin, Advisor Jay Hobgood Bryan Mark Copyrighted by Alexander Michael McCarthy 2017 Abstract While aircraft penetration data of oceanic thunderstorms has been collected in several field campaigns between the 1970’s and 1990’s, the continental data they were compared to all stem from penetrations collected from the Thunderstorm Project in 1947. An analysis of an updated dataset where modern instruments allowed for more accurate measurements was used to make comparisons to prior oceanic field campaigns that used similar instrumentation and methodology. Comparisons of diameter and vertical velocity were found to be similar to previous findings. Cloud liquid water content magnitudes were found to be significantly greater over the oceans than over the continents, though the vertical profile of oceanic liquid water content showed a much more marked decrease with height above 4000 m than the continental profile, lending evidence that entrainment has a greater impact on oceanic convection than continental convection. The difference in buoyancy between vigorous continental and oceanic convection was investigated using a reversible CAPE calculation. It was found that for the strongest thunderstorms over the continents and oceans, oceanic CAPE values tended to be significantly higher than their continental counterparts. Alternatively, an irreversible CAPE calculation was used to investigate the role of entrainment in reducing buoyancy for continental and oceanic convection where it was found that entrainment played a greater role in diluting oceanic buoyancy than continental buoyancy. ii Acknowledgments I would like to begin by thanking my advisor Dr. Jialin Lin for his guidance and support with this research. Without his help with data collection and lessons in scientific programming, this research would not have been possible. I also would like to thank my additional committee members Dr. Jay Hobgood and Dr. Bryan Mark who helped provide additional suggestions and revisions for this thesis. In addition, I would like to thank Jim Degrand, Dr. Jeffrey Rogers, and Dr. Alvaro Montenegro, as well as my aforementioned committee members, for providing the educational framework for my knowledge of the Atmospheric Sciences. Furthermore, special thanks go to the staff of Delaware County Emergency Management Agency including Sean Miller, Sandy Mackey, and Bob Lavender for allowing me the opportunity to intern with them over the last two years, thus allowing me to apply my meteorological background to public safety. For their technical assistance, I would like to thank Zach McCarthy for assistance with programming and statistical analysis, as well as Stephen Shield for his assistance with ArcGIS. Lastly, I would like to thank my family, John, Karen, and Ryan McCarthy, for their support through graduate school. iii Vita May, 2011 ......................................................Canton Central Catholic High School May, 2015 .....................................................B.S. Atmospheric Science, The Ohio State University Fields of Study Major Field: Atmospheric Sciences iv Table of Contents Abstract ............................................................................................................................... ii Acknowledgments.............................................................................................................. iii Vita ..................................................................................................................................... iv List of Tables ..................................................................................................................... vi List of Figures ................................................................................................................. vvii List of Abbreviations .......................................................................................................... x List of Constants and Variables ......................................................................................... xi Chapter 1: Introduction ...................................................................................................... 1 Chapter 2: Datasets Gathered for Analysis ....................................................................... 17 Chapter 3: Methodology ................................................................................................... 26 Chapter 4: Analysis of Aircraft Penetration Data ............................................................. 30 Chapter 5: Analysis of Oceanic Soundings ...................................................................... 63 Chapter 6: Conclusions ..................................................................................................... 77 References ......................................................................................................................... 81 Appendix A: Updraft Selection Program .......................................................................... 86 Appendix B: CAPE Calculation Program......................................................................... 89 v List of Tables Table 1. Dates and times of flights in the North Dakota Tracer Experiment ................... 19 Table 2. Flight dates and times from the Convection and Precipitation Electrification Experiment ........................................................................................................................ 20 Table 3. Flight dates and times from the Cooperative Oklahoma Profiler Study ............. 20 Table 4. Flight dates and times from the Vortex 1994 field experiment .......................... 21 Table 5. Flight dates and times from the Vortex 1995 field experiment .......................... 21 Table 6. Sites of acquisition of continental precipitaiton data and soundings .................. 23 Table 7. Sites of acquision of oceanic precipitation data and sounidings ........................ 25 Table 8. Relationship between diameter and mean vertical velocity at three different altitude ranges; 2500m-3800m, 3800m-5000m, and 5000m-6200m................................ 40 Table 9. Relationship between diameter and maximum vertical velocity at three different altitude ranges; 2500m-3800m, 3800m-5000m, and 5000m-6200m................................ 41 vi List of Figures Figure 1. Locations of field campaigns and atomspheric soudings used in this thesis ..... 17 Figure 2. Continental updraft diameters from Florida, Oklahoma, and South Dakota thunderstorm penetrations ................................................................................................. 31 Figure 3. Continental updraft mean vertical velocitys from Florida, Oklahoma, and South Dakota thunderstorm penetrations .................................................................................... 33 Figure 4. Continental updraft maximum vertical velocity from Florida, Oklahoma, and South Dakota thunderstorm penetrations .......................................................................... 34 Figure 5. Continental updraft liquid water content from Florida, Oklahoma, and South Dakota thunderstorm penetrations .................................................................................... 35 Figure 6. Vertical profile of continental uprdraft core diameters ..................................... 37 Figure 7. Vertical profile of continental updraft core mean vertical velocity .................. 38 Figure 8. Vertical profile of continental updraft core maximum vertical velocity ........... 38 Figure 9. Relationship between continental updraft core diameter and mean vertical velocity .............................................................................................................................. 39 Figure 10. Relationship between diameter and maximum vertical velocity for continental updraft cores...................................................................................................................... 41 Figure 11. Vertical profile of continetnal updraft core liquid water content .................... 42 vii Figure 12. Continental downdraft core diamters from Florida, Oklahoma, and South Dakota thunderstorm penetrations. ................................................................................... 43 Figure 13. Continental downdraft mean vertical velocity from Florida, Oklahoma, and South Dakota thunderstorm penetrations .......................................................................... 44 Figure 14. Continental downdraft maximum vertical velocity from Florida, Oklahoma, and South Dakota thunderstorm penetrations ................................................................... 45 Figure 15. Continental downdraft liquid water content from Florida, Oklahoma, and South Dakota thunderstorm penetrations .......................................................................... 46 Figure 16. Vertical profile of continental downdraft core diameters ............................... 47 Figure 17. Vertical profile of continental downdraft core mean vertical velocity ............ 48 Figure 18. Vertical profile of continental downdraft core maximum vertical
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