An Evaluation of a Point Snow Model and a Mesoscale Model
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AN EVALUATION OF A POINT SNOW MODEL AND A MESOSCALE MODEL FOR REGIONAL CLIMATE SIMULATIONS by Jason Thomas Butke A thesis submitted to the Faculty of the University of Delaware in partial fulfillment of the requirements for the degree of Master of Science in Geography Fall 2006 Copyright 2006 Jason Thomas Butke All Rights Reserved UMI Number: 1440623 UMI Microform 1440623 Copyright 2007 by ProQuest Information and Learning Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. ProQuest Information and Learning Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, MI 48106-1346 AN EVALUATION OF A POINT SNOW MODEL AND A MESOSCALE MODEL FOR REGIONAL CLIMATE SIMULATIONS by Jason Thomas Butke Approved: __________________________________________________________ Brian Hanson, Ph.D. Professor in charge of thesis on behalf of the Advisory Committee Approved: __________________________________________________________ Brian Hanson, Ph.D. Interim Chair of the Department of Geography Approved: __________________________________________________________ Thomas Apple, Ph.D. Dean of the College of Arts and Sciences Approved: __________________________________________________________ Daniel Rich, Ph.D. Provost ACKNOWLEDGMENTS I would firstly like to express my gratitude to my thesis advisor, Dr. Brian Hanson, for his expertise, knowledge, and understanding, all of which added considerably to my graduate experience. His brilliance with computers and modeling is second to no one, and his assistance in understanding concepts greatly impacted my perception of numerical modeling. I would also like to thank my committee members Dr. Daniel Leathers and Dr. Andrew Grundstein for their assistance in all aspects of my research project. Finally, I would like to thank Dr. Cort Willmott for his expertise and sincere guidance in more than just academic affairs. A special thank you goes to Dr. Arthur Samel, without whose motivation and encouragement I may not have considered a graduate career in climatological research. Dr. Samel is the one professor who truly made a difference in my life. It was under his tutelage that I developed a focus and gained confidence. He provided me with direction, technical support, and became more of a mentor and friend, than a professor. It was through his persistence, understanding, and kindness that I completed my undergraduate degree and was encouraged to apply for higher education. I doubt that I will ever be able to convey my appreciation fully, but I owe him my eternal gratitude. I would also like to thank my mother, Barbara Butke, for putting up with me since childbirth, raising me well, and working so hard to provide for our family, in the absence of my father. Without her hard work and determination, I would not be the person that I am today or come as far as I have. A thank you goes to the National Center for Atmospheric Research (NCAR) for their computing resources and data that aided in running MM5. In conclusion, I recognize that this research would not have been possible without the financial assistance of the Department of Geography at the University of Delaware (teaching and research assistantships), and so I express my sincere gratitude. TABLE OF CONTENTS LIST OF TABLES .................................................................................................... iv LIST OF FIGURES.................................................................................................... x NOMENCLATURE................................................................................................ xiii ABSTRACT............................................................................................................. xx 1 LITERATURE REVIEW............................................................................. 1 1.1 Introduction........................................................................................... 1 1.2 Project Objectives ................................................................................. 2 1.3 Snow Physics in the Climate System..................................................... 2 1.3.1 Micro-Scale Effects .................................................................. 2 1.3.2 The Forest Canopy and Blowing Snow Effects ......................... 6 1.3.3 Ablation and Regional Hydrological Impacts............................ 7 1.4 Snow Cover Modeling........................................................................... 8 1.4.1 Introduction.............................................................................. 8 1.4.2 Snow Model Types................................................................... 9 1.4.3 Complex One-Dimensional Snow Models .............................. 10 1.4.4 Simple One-Dimensional Snow Models.................................. 13 1.5 General Circulation Models and Mesoscale Models ............................ 14 1.6 Research Objectives ............................................................................ 16 2 SNTHERM.................................................................................................. 18 2.1 Introduction......................................................................................... 18 2.2 Conservation Equations....................................................................... 19 2.3 Surface Energy Balance ...................................................................... 23 3 MM5............................................................................................................ 26 3.1 Model System Components................................................................. 26 3.2 General Equations............................................................................... 29 3.3 Cloud Schemes.................................................................................... 32 3.4 Precipitation Schemes ......................................................................... 33 3.5 Radiation Schemes.............................................................................. 33 3.6 Surface Schemes ................................................................................. 34 3.7 Model Setup........................................................................................ 35 i 4 MODEL SNOW PHYSICS ........................................................................ 38 4.1 NOAH LSM Snow Model Introduction............................................... 38 4.2 Precipitation Rate................................................................................ 40 4.3 Snow Albedo ...................................................................................... 41 4.4 Thermal Conductivity ......................................................................... 42 4.5 New Snow Density.............................................................................. 47 4.6 Ablation .............................................................................................. 48 4.7 Surface Energy Budget........................................................................ 50 4.7.1 Turbulent Exchange Fluxes..................................................... 51 4.7.2 Snow/Ground Interface Temperature ...................................... 52 4.7.3 Snow/Ground Interface Heat Flux........................................... 54 4.8 SNTHERM Snow Compaction, Metamorphosis, and Grain Growth.... 55 5 DATA AND METHODOLOGY ................................................................ 57 5.1 SNTHERM Input Data........................................................................ 57 5.2 MM5 Input Data ................................................................................. 58 5.3 Observation Data................................................................................. 60 5.3.1 Snow Observation Errors........................................................ 60 5.3.2 NCDC Data Errors.................................................................. 61 5.4 Model Sensitivity Analysis.................................................................. 61 5.5 Model Evaluation Statistics................................................................. 63 6 RESULTS.................................................................................................... 66 6.1 General Model Analysis...................................................................... 67 6.2 Heavy Snow Events ............................................................................ 70 6.2.1 Anomalous Event ................................................................... 71 6.3 Model Evaluation................................................................................ 72 6.4 Snow Physics Evaluation .................................................................... 83 6.4.1 Snow Albedo .......................................................................... 84 6.4.2 Turbulent Exchange Fluxes..................................................... 86 6.4.3 Snow Ground Interface........................................................... 88 6.4.4 Subsurface Temperatures........................................................ 99 6.4.5 Snow/Ground Interface Heat Flux......................................... 115 ii 7 DISCUSSION AND CONCLUSIONS ..................................................... 117 7.1 Discussion......................................................................................... 117 7.2 Conclusions......................................................................................