University of North Dakota UND Scholarly Commons Theses and Dissertations Theses, Dissertations, and Senior Projects January 2018 An Investigation Of Severe Weather Environments In Atmospheric Reanalyses Austin Taylor King Follow this and additional works at: https://commons.und.edu/theses Recommended Citation King, Austin Taylor, "An Investigation Of Severe Weather Environments In Atmospheric Reanalyses" (2018). Theses and Dissertations. 2251. https://commons.und.edu/theses/2251 This Thesis is brought to you for free and open access by the Theses, Dissertations, and Senior Projects at UND Scholarly Commons. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of UND Scholarly Commons. For more information, please contact [email protected]. AN INVESTIGATION OF SEVERE WEATHER ENVIRONMENTS IN ATMOSPHERIC REANALYSES by Austin Taylor King Bachelor of Science, University of Oklahoma, 2016 A Thesis Submitted to the Graduate Faculty of the University of North Dakota in partial fulfillment of the requirements for the degree of Master of Science Grand Forks, North Dakota May 2018 Copyright 2018 Austin King ii PERMISSION Title An Investigation of Severe Weather Environments in Atmospheric Reanalyses Department Atmospheric Sciences Degree Master of Science In presenting this thesis in partial fulfillment of the requirements for a graduate degree from the University of North Dakota, I agree that the library of this University shall make it freely available for inspection. I further agree that permission for extensive copying for scholarly purposes may be granted by the professor who supervised my thesis work or, in his absence, by the Chairperson of the department or the dean of the School of Graduate Studies. It is understood that any copying or publication or other use of this thesis or part thereof for financial gain shall not be allowed without my written permission. It is also understood that due recognition shall be given to me and to the University of North Dakota in any scholarly use which may be made of any material in my thesis. Austin Taylor King May 4, 2018 iv TABLE OF CONTENTS LIST OF FIGURES .......................................................................................................... vii LIST OF TABLES ............................................................................................................ ix ACKNOWLEDGMENTS .................................................................................................. x ABSTRACT ...................................................................................................................... xi CHAPTER I. INTRODUCTION ..................................................................................... 1 Background .................................................................................... 1 Severe Weather in Atmospheric Reanalyses ...................... 1 Trends in Severe Weather Environments ........................... 4 Purpose of Study ............................................................................. 7 II. REANALYSIS DATASETS ..................................................................... 9 Overview ......................................................................................... 9 Details ........................................................................................... 10 NARR ............................................................................... 10 ERA-Interim ..................................................................... 10 MERRA2 .......................................................................... 11 JRA55 ............................................................................... 12 v 20CR ................................................................................. 12 CFSR ................................................................................ 13 III. METHODS .............................................................................................. 15 Reanalysis Comparison ................................................................ 15 Climatology .................................................................................. 19 IV. EXAMPLE CASES ................................................................................. 28 3 May 1999 OKC .......................................................................... 28 18 July 2004 GFK ......................................................................... 31 V. RESULTS ................................................................................................. 41 Reanalysis Performance and Comparison .................................... 41 Statistical Results ............................................................. 41 Comparison of Reanalyses to T03 and T07 ..................... 44 Climatology and Trends in Severe Weather Parameters .............. 47 Climatology ...................................................................... 48 Trends in Environments Favorable for Severe Weather .. 49 VI. DISCUSSION ........................................................................................... 76 Reanalysis Performance and Comparison .................................... 76 Climatology and Trends in Severe Weather Parameters .............. 79 VII. SUMMARY AND CONCLUSIONS ....................................................... 84 Reanalysis Performance and Comparison .................................... 84 Climatology and Trends in Severe Weather Parameters .............. 86 REFERENCES ................................................................................................................. 88 vi LIST OF FIGURES Figure Page 1. Box and whiskers plots of MLCAPE and ESRH for RUC-2 proximity soundings sorted by storm type .................................................................................... 27 2. Surface analyses for RUC-2 at 23 UTC 3 May 1999 and reanalyses at 00 UTC 4 May 1999 .................................................................................................... 34 3. 500 mb analyses for RUC-2 at 23 UTC 3 May 1999 and reanalyses at 00 UTC 4 May 1999 .................................................................................................... 35 4. Proximity soundings near Oklahoma City, OK for RUC-2 at 23 UTC 3 May 1999 and reanalyses at 00 UTC 4 May 1999 ................................................... 36 5. Observed sounding for Norman, OK (OUN) at 00 UTC 4 May 1999 ......................... 37 6. 00 UTC 19 July 2004 surface analyses for the reanalyses ........................................... 38 7. 00 UTC 19 July 2004 500 mb analyses for the reanalyses .......................................... 39 8. Proximity soundings near Grand Forks, ND for RUC-2 at 23 UTC 3 May 1999 and reanalyses at 00 UTC 19 July 2004 .................................................. 40 9. Box and whiskers plots of MLCAPE, EFFSRH, SCP, and 0-1 km bulk shear for RUC-2 and the reanalyses ............................................................................ 58 10. Violin plots of MLCAPE for RUC-2 and the reanalyses .......................................... 59 11. Violin plots of EFFSRH for RUC-2 and the reanalyses ............................................ 60 12. Violin plots of 0-1 km bulk shear for RUC-2 and the reanalyses .............................. 61 13. Violin plots of SCP for RUC-2 and the reanalyses .................................................... 62 14. Violin plots of STP for RUC-2 and the reanalyses .................................................... 63 15. Average number of days during the period of 1986-2015 with 00 UTC NARR MUCAPE values exceeding 2000 J kg-1 and MLCAPE values exceeding 2000 J kg-1 ................................................................................................. 64 vii 16. Average number of days during the period of 1986-2015 with 00 UTC product of NARR MUCAPE and 0-6 km shear exceeding 20,000 ........................... 65 17. Average number of days during the period of 1986-2015 with 00 UTC NARR SCP exceeding 2 ............................................................................................ 66 18. Linear trend in days with NARR 00 UTC MLCAPE values exceeding 2000 J kg-1 for each season ........................................................................................ 67 19. Linear trend in days with NARR 00 UTC MUCAPE values exceeding 2000 J kg-1 for each season ........................................................................................ 68 20. Linear trend in days with NARR 00 UTC MLCIN values exceeding -75 J kg-1 for each season ........................................................................................... 69 21. Linear trend in days with NARR 00 UTC 0-6 km shear values exceeding 40 kts for each season ................................................................................................ 70 22. Linear trend in days with NARR 00 UTC SCP values exceeding 2 for each season ................................................................................................................. 71 23. Linear trend in days with NARR 00 UTC EFFSRH values exceeding 100 m2s2 for each season ............................................................................................ 72 24. Linear trend in days with NARR 00 UTC EBWD values exceeding 15 ms-1 for each season .............................................................................................. 73 25. Linear trend in days with MLCAPE