Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2018 Understanding diurnal cycle mode intensification and its effect on interannual and interdecadal warm season precipitation trends over the U.S. Corn Belt Amanda Black Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Part of the Meteorology Commons Recommended Citation Black, Amanda, "Understanding diurnal cycle mode intensification and its effect on interannual and interdecadal warm season precipitation trends over the U.S. Corn Belt" (2018). Graduate Theses and Dissertations. 16791. https://lib.dr.iastate.edu/etd/16791 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Understanding diurnal cycle mode intensification and its effect on interannual and interdecadal warm season precipitation trends over the U.S. Corn Belt by Amanda Suzanne Black A dissertation submitted to the graduate faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Major: Meteorology Program of Study Committee: Xiaoqing Wu, Major Professor Tsing-Chang Chen Gene S. Takle Raymond W. Arritt William J. Gutowski The student author, whose presentation of the scholarship herein was approved by the program of study committee, is solely responsible for the content of this dissertation. The Graduate College will ensure this dissertation is globally accessible and will not permit alterations after a degree is conferred. Iowa State University Ames, Iowa 2018 Copyright © Amanda Suzanne Black, 2018. All rights reserved. ii DEDICATION To my mother, Susan, and my father, Dan “The Man” Black. iii TABLE OF CONTENTS LIST OF FIGURES ....................................................................................................................... vi LIST OF TABLES ........................................................................................................................ xii ACKNOWLEDGEMENTS ......................................................................................................... xiii ABSTRACT ................................................................................................................................. xiv CHAPTER 1. GENERAL INTRODUCTION ............................................................................... 1 1.1 Research Objectives ............................................................................................................ 4 1.2 References ........................................................................................................................... 5 CHAPTER 2. THE ROLE OF THE DIURNAL CYCLE MODE ON WARM SEASON PRECIPITATION THROUGH ITS RELATIONSHIP TO THE GREAT PLAINS LOW-LEVEL JET .......................................................................................................................... 8 Abstract ..................................................................................................................................... 8 2.1 Introduction ......................................................................................................................... 9 2.2 Methods............................................................................................................................. 11 2.2.1 Data .......................................................................................................................... 11 2.2.1.1 Climate Forecast System Reanalysis .............................................................. 11 2.2.1.2 North American Regional Reanalysis ............................................................. 11 2.2.1.3 Nesting Technique .......................................................................................... 13 2.2.2 GPLLJ identification ................................................................................................ 14 2.2.3 Water vapor flux transport derivation ...................................................................... 15 2.2.4 Diurnal component isolation technique ................................................................... 17 2.3 Results ............................................................................................................................... 18 2.3.1 Synoptic environments of GPLLJ events ................................................................ 18 2.3.2 GPLLJ water vapor transport ................................................................................... 22 2.3.3 Climatological water vapor transport....................................................................... 25 2.4 Discussion ......................................................................................................................... 26 2.5 Conclusions ....................................................................................................................... 28 2.6 Acknowledgements ........................................................................................................... 29 2.7 References ......................................................................................................................... 29 CHAPTER 3. INVESTIGATING THE EFFECT OF DIURNAL CYCLE MODE INTENSIFICATION ON INTERANNUAL VARIATION AND EXTREME RAINFALL EVENTS OVER THE U.S. CORN BELT ................................................................................... 32 Abstract ................................................................................................................................... 32 3.1 Introduction ....................................................................................................................... 33 3.2 Methods............................................................................................................................. 36 3.2.1 Data .......................................................................................................................... 36 iv 3.2.1.1 Climate Forecast System Reanalysis .............................................................. 36 3.2.1.2 North American Regional Reanalysis ............................................................. 37 3.2.1.3 Nesting Technique .......................................................................................... 37 3.2.2 Extreme event selection ........................................................................................... 38 3.2.2.1 Flood events ................................................................................................. 38 3.2.2.2 Drought events ............................................................................................. 39 3.2.3 Water vapor flux transport derivation ...................................................................... 41 3.2.4 Diurnal component isolation technique ................................................................... 42 3.3 Results ............................................................................................................................... 43 3.3.1 Monthly phase and amplitude of diurnal fields ....................................................... 43 3.3.2 Composite 3-hourly diurnal fields ........................................................................... 45 3.3.3 Phase and amplitude of extreme events ................................................................... 47 3.4 Discussion ......................................................................................................................... 51 3.4.1 Interannual variation ................................................................................................ 51 3.4.2 Extreme events compared to climatology ................................................................ 52 3.5 Conclusions ....................................................................................................................... 53 3.6 Acknowledgements ........................................................................................................... 53 3.7 Appendix A. NCDC PDSI plots ....................................................................................... 54 3.7.1 Criteria 1 drought events .......................................................................................... 54 3.7.2 Criteria 2 drought events .......................................................................................... 55 3.8 References ......................................................................................................................... 58 CHAPTER 4. AN EVALUATION OF THE DECADAL INCREASE IN WARM SEASON RAINFALL OVER THE U.S. CORN BELT ............................................................................... 61 Abstract ................................................................................................................................... 61 4.1 Introduction ....................................................................................................................... 62 4.2 Methods............................................................................................................................. 64 4.2.1 Data .........................................................................................................................