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An Analysis of the Moisture and Moist Static Energy Budgets in AMIP Simulations

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An Analysis of the Moisture and Moist Static Energy Budgets in AMIP Simulations An Analysis of the Moisture and Moist Static Energy Budgets in AMIP Simulations by Kristine Adelaide Boykin Bachelor of Science Physics Southern Polytechnic State University 2004 A thesis submitted to the Department of Marine and Environmental Systems at Florida Institute of Technology in partial fulfilment of the requirements for the degree of Master of Science in Meteorology Melbourne, Florida September, 2016 © Copyright 2016 Kristine Adelaide Boykin All Rights Reserved The author grants permission to make single copies_____________________________ We the undersigned committee hereby recommend that the attached document be accepted as fulfilling in part of the requirements for the degree of Master of Science of Meteorology. An Analysis of the Moisture and Moist Static Energy Budgets in AMIP Simulations by Kristine Adelaide Boykin _____________________________________________ P. K. Ray, Ph.D., Major Advisor Assistant Professor, Marine and Environmental Systems _____________________________________________ G. Maul, Ph.D. Professor of Oceanography _____________________________________________ M. Bush, Ph.D. Professor of Biological Sciences _____________________________________________ T. Waite, Ph.D., Department Head Marine and Environmental Systems Abstract An Analysis of the Moisture and Moist Static Energy Budgets in AMIP S by Kristine Adelaide Boykin Major Advisor: P. K. Ray, Ph.D. An analysis of the second phase of the Atmospheric Model Intercomparison Project (AMIP) simulations has been conducted to understand the physical processes that control precipitation in the tropics. This is achieved primarily through the analysis of the moisture and moist static energy budgets. Overall, there is broad agreement between the simulated and observed precipitation, although specific tropical regions such as the Maritime Continent poses challenges to these simulations. The models in general capture the latitudinal distribution of precipitation and key precipitating regions including the Inter- Tropical Convergence Zone (ITCZ) and the Asian Monsoon. The simulations portrayed the global patterns of evaporation and precipitation relatively accurately, confirming that the ocean was the primary source of evaporation. The ensemble of simulations proved to be the most reliable simulation of the moisture budget globally, within the tropics, and the Maritime Continent. A strong relationship between precipitation and vertical advection, or horizontal convergence, is seen among the observations and simulations. Some simulations were more successful than others in reproducing the largest amount of rainfall over the islands in the Maritime iii Continent. The moist static energy budget proved difficult to simulate without large residual values, both in the tropics and the Maritime Continent. The total radiation and surface heat flux displayed lesser values of outgoing radiation and incoming surface heat, respectively, across major precipitation and convergence regions such as the ITCZ and the Indian Monsoon. The residual values were often smaller over areas of larger precipitation, such as the ITCZ, but spiked in value elsewhere. This resulted in a larger overall residual value for the tropical region, but a slightly smaller residual over the Maritime Continent as larger residual spikes fell further afield. However, considering the overall size of the residual values, the observations and simulations are not successful at demonstrating the moist static energy budget. iv Table of Contents List of Keywords vii List of Figures viii List of Tables ix List of Abbreviations x Acknowledgement xi Chapter 1 Introduction 1 1.1 Overview of AMIP and its Objectives 3 1.2 Previous Studies 5 1.3 Objectives 6 1.3.1 Organization of thesis 6 Chapter 2 Models, Data, and Method 7 2.1 Models 7 2.2 Data 10 2.3 Method 12 Chapter 3 Moisture Budget 15 3.1 Global Precipitation 15 3.1.1 Precipitation Difference 21 3.1.2 Zonally Averaged Precipitation 27 3.1.3 Annual Cycle of Precipitation 28 3.1.4 Statistic of Simulated Global Precipitation 30 3.2 Precipitation – Evaporation 32 3.3 Annual cycle of the global Moisture Budget 37 3.3.1 Comparison of Monthly Global Means 38 3.4 Mean Moisture Budget in the Tropics 41 3.4.1 Statistics of Simulated Tropical Moisture Budget 44 3.5 Annual Cycle of the Tropical Moisture Budget 51 3.5.1 Comparison of Monthly Tropical Means 51 3.6 Discussion 54 Chapter 4 Moist Static Energy Budget 57 4.1 Mean Moist Static Energy Budget 57 v 4.1.1 Statistics of the Tropical Moist Static Energy Budget 60 4.2 Annual cycle of the tropical Moist Static Energy Budget 68 4.2.1 Comparison of Monthly Tropical Means 68 4.2.2 Comparison of Monthly Tropical Perturbations 71 4.3 Discussion 72 Chapter 5 A case study on the Maritime Continent 74 5.1 The Moisture Budget 74 5.1.1 Statistics of the Moisture Budget 78 5.2 Annual Cycle 85 5.2.1 Comparison of the Monthly Means 85 5.2.2. Comparison of the Monthly Perturbations 88 5.3 The Moist Static Energy Budget 88 5.3.1 Statistics of the Moist Static Energy Budget 91 5.4 Annual Cycle 98 5.4.1 Comparison of Monthly Means 98 5.4.2 Comparison of Monthly Perturbations 99 5.5 Discussion 102 Chapter 6 Summary and Conclusion 105 References 111 Appendix A Chapter 3 114 Appendix B Chapter 4 130 Appendix C Chapter 5 145 vi List of Keywords AMIP CMAP ITCZ Maritime Continent Moist Static Energy Budget Moisture Budget NCEP-DOE Reanalysis 2 Precipitation Tropics vii List of Figures 1.1 Climatological mean precipitation from CMAP 2 1.2 CMIP5 Schematics 4 3.1 Climactic Mean Precipitation 17 3.2 Difference of Mean Precipitation 22 3.3 Zonally averaged time mean precipitation 28 3.4 Annual cycle of precipitation, model minus observations 29 3.5 Precipitation - Evaporation 33 3.6 Monthly Global Means of the Moisture Budget 39 3.7 Monthly Mean Moisture Budget Perturbations, Global 40 3.8 Tropical Mean Moisture Budget 42 3.9 Monthly Mean Moisture Budget Terms, Tropics 52 3.10 Monthly Mean Moisture Budget Perturbations, Tropics 53 4.1 Tropical Climactic Mean MSE Budget 58 4.2 Monthly Means of the MSE 69 4.3 Monthly Mean MSE budget perturbations 70 5.1 Climactic Mean Moisture Budget in the Maritime Continent 75 5.2 Monthly Means of the Moisture Budget in the Maritime Continent 86 5.3 Monthly Mean Moisture Budget Perturbations 87 5.4 Climactic Mean Moist Static Energy Budget in the Maritime Continent 89 5.5 Monthly Means of the MSE in the Maritime Continent 100 5.6 Monthly Mean MSE budget perturbations in the Maritime Continent 101 A.1 Identifying Lines 115 A.2 Climactic Mean Moisture Budget in the Tropics 116 B.1 Climactic Mean MSE Budget in the Tropics 131 C.1 Climactic Mean of the Moisture Budget in the Maritime Continent 147 C.2 Climactic Mean of the MSE Budget in the Maritime Continent 161 viii List of Tables 2.1 Model Information. 8 2.2 Model Resolution. 9 3.1 Climatological statistics of Precipitation over the globe. 31 3.2 Climatological statistics of Precipitation over the tropics 45 3.3 Climatological statistics of Evaporation over the tropics 46 3.4 Climatological statistics of Horizontal Advection over the tropics 47 3.5 Climatological statistics of Convergence over the tropics 48 3.6 Climatological statistics of Residual over the tropics 49 4.1 Climatological statistics of MSE Advection over the tropics 61 4.2 Climatological statistics of MSE Convergence over the tropics 63 4.3 Climatological statistics of Total Radiation over the tropics 64 4.4 Climatological statistics of Total Heat Flux over the tropics 65 4.5 Climatological statistics of MSE Residual over the tropics 67 5.1 Climatological statistics of Precipitation over the Maritime Continent 79 5.2 Climatological statistics of Evaporation over the Maritime Continent 80 5.3 Climatological statistics of Horizontal Advection over the Maritime Continent 82 5.4 Climatological statistics of Convergence over the Maritime Continent 83 5.5 Climatological statistics of Residual over the Maritime Continent 84 5.6 Climatological statistics of MSE Advection over the Maritime Continent. 92 5.7 Climatological statistics of MSE Convergence over the Maritime Continent 94 5.8 Climatological statistics of Total Radiation over the Maritime Continent 95 5.9 Climatological statistics of Total Heat Flux over the Maritime Continent 96 5.10 Climatological statistics of MSE Residual over the Maritime Continent 97 ix List of Abbreviations AMIP: Atmospheric Model Intercomparison Project CMAP: CPC Merged Analysis of Precipitation CMIP: Coupled Model Intercomparison Project ITCZ: Intertropical Convergence Zone MSE: Moist Static Energy NCEP-DOE: National Centers for Environmental Prediction, Department of Energy RMSE: Root Mean Squared Error x Acknowledgement I would like to express my sincere gratitude to my advisor, Dr. Pallav Ray, for his constant support, expertise, patience, and for making a long distance research thesis possible. I would also like to thank my thesis committee, Dr. George Maul and Dr. Mark Bush, for their helpful insights and critiques, and my fellow graduate student Marcus Morgan for his knowledge and troubleshooting. My degree would not have been possible without the financial support of the Department of Marine and Environmental Systems, the Deering-Irlandi Fellowship Fund, the Gertrude E. Skelly Charitable Foundation, and the John M. Williams Fellowship Endowment. Finally, I would like to thank my husband, Aiken Oliver, for his constant support and encouragement as I worked diligently to complete my goal. xi Chapter 1 Introduction Precipitation is an important part of our daily lives. Not only does precipitation affect various industries, from agriculture to shipping, but it also affects our local weather and climate, and by extension, the global weather and climate. As a result, understanding and forecasting of precipitation is vital. Figure 1.1 shows the climatological mean of precipitation from the CPC Merged Analysis of Precipitation (CMAP) observations. Major regions of high precipitation fall within the tropics (30°S-30°N), such as the Indian Monsoon region, the Inter-Tropical Convergence Zone (ITCZ), and the Maritime Continent.
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