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Studies of Blowing Snow and Its Impact on the Atmospheric Surface Layer

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Studies of Blowing Snow and Its Impact on the Atmospheric Surface Layer STUDIES OF BLOWING SNOW AND ITS IMPACT ON THE ATMOSPHERIC SURFACE LAYER SERGIY A. SAVELYEV A DISSERTATION SUBMITTED TO THE FACULTY OF GRADUATE STUDIES IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY GRADUATE PROGRAM IN EARTH AND SPACE SCIENCE YORK UNIVERSITY TORONTO, ONTARIO MAY 2011 Library and Archives Bibliotheque et 1*1 Canada Archives Canada Published Heritage Direction du Branch Patrimoine de I'edition 395 Wellington Street 395, rue Wellington OttawaONK1A0N4 Ottawa ON K1A 0N4 Canada Canada Your file Votre re'fGrence ISBN: 978-0-494-80554-1 Our file Notre r6f6rence ISBN: 978-0-494-80554-1 NOTICE: AVIS: The author has granted a non­ L'auteur a accorde une licence non exclusive exclusive license allowing Library and permettant a la Bibliotheque et Archives Archives Canada to reproduce, Canada de reproduire, publier, archiver, publish, archive, preserve, conserve, sauvegarder, conserver, transmettre au public communicate to the public by par telecommunication ou par Nnternet, preter, telecommunication or on the Internet, distribuer et vendre des theses partout dans le loan, distribute and sell theses monde, a des fins commerciales ou autres, sur worldwide, for commercial or non­ support microforme, papier, electronique et/ou commercial purposes, in microform, autres formats. paper, electronic and/or any other formats. The author retains copyright L'auteur conserve la propriete du droit d'auteur ownership and moral rights in this et des droits moraux qui protege cette these. Ni thesis. Neither the thesis nor la these ni des extraits substantiels de celle-ci substantial extracts from it may be ne doivent etre imprimes ou autrement printed or otherwise reproduced reproduits sans son autorisation. without the author's permission. In compliance with the Canadian Conformement a la loi canadienne sur la Privacy Act some supporting forms protection de la vie privee, quelques may have been removed from this formulaires secondares ont ete enleves de thesis. cette these. While these forms may be included Bien que ces formulaires aient inclus dans in the document page count, their la pagination, il n'y aura aucun contenu removal does not represent any loss manquant. of content from the thesis. 1+1 Canada Abstract In January - May of 2004 as a part of the Canadian Arctic Shelf Exchange Study experiment, an on-ice camp and a meteorological measurement site were established on first-year landfast ice. Standard meteorological and turbulent flux measuring in­ strumentation was complimented with a set of sensors dedicated to the detection of airborne particles and measurements of various parameters of snow transport. Snow cover probing and manual observations at the ship meteorological station and on the ice were performed on schedule according to the activities plan. Pho­ toelectric particle detectors, designed and fabricated at York University, Toronto, were installed at various heights above the snow surface and provided continuous information on snow particle flux during this period. Drifting or blowing of snow in the course of the experiment was detected for 40% of the time. The criteria for blowing snow event was to last at least one hour and be separated from the previous event by greater than one hour. These criteria resulted in identification of 32 events. We propose a method of prediction of the iv threshold wind speed that has to be attained for blowing to begin. The method is different for three types of snow surface forming processes: solid precipitation, hoarfrost deposition and wind hardening. The aerodynamic roughness length Zom for snow covered seasonal ice was derived from pairs of wind speed and temperature profiles measured during the experiment. Its median value is 0.001 m with variations that span two orders of magnitude. This value is valid for flow with friction velocity u* greater than 0.35 m s"1 and less than 0.7 m s_1 (maximum encountered). No dependency of roughness length on suspended snow particle density in the reported range of u* was revealed. The Maximum Likelihood approach is at the base of our profile fitting procedure. The effect of random measurement errors on the result of fitting is examined. The quantitative assessment of the particle load in the multicomponent flow requires proper instruments to measure mass or volume fraction of individual con­ stituents. Three generations of photo-electronic counters have been developed. The first two variants only counted particles without sizing them. The third variant has an ability to measure the time-of-flight of the particle through the sensor field of view. This time can be converted into estimates of the particle size if certain assumptions are made. Calibration procedures are developed that allow for accu­ rate estimation of the minimum detected particle diameters depending on both the particle position in the sampling volume and its speed. v Acknowledgements My first and foremost gratitude goes to Professor Peter Taylor. It is with his guidance and help that this work came to a conclusion. In so many ways he influenced my way through the graduate studies that emphasizing just the scientific supervision does not do full justice to his role. I consider him my mentor and role model. I am grateful to my supervisors, John Miller and Jack McConnell for challenging me to be better, for encouraging me or warning when I tried to do things beyond my abilities. Professor John Pomeroy jump-started our work with particle counters. Many thanks to personnel of Electronics and Machine Shops of the Faculty of Science and Engineering of the York University. Jim Hodges and Harvey Emberley patiently translated our vague ideas into precise electronics design. The microcontroller ex­ pert Ivan Nesterenko made the third generation of counters possible. One can not wish for better chance to upgrade knowledge and professional vi experience than the opportunity I've been given in the overwintering expedition on the board of the CCGS "Amundsen". Funding for this work was provided by the Canadian Foundation for Climate and Atmospheric Sciences (CFCAS). Space on the Amundsen during CASES was made available through ArcticNet. I thank the entire crew and the group of researchers that made this experiment unforgettable. Names of my closest colleagues Mark Gordon of York University and Professor Tim Papakyriakou of University of Manitoba have to be mentioned in particular. Professor John Hanesiak was not on the ship in person but contributed in many ways from his office at University of Manitoba. The scientific collaboration with him resulted in several published papers. Professor Cheryll McKenna-Neuman provided us with the opportunity and as­ sistance to investigate the performance of particle counters in wind tunnel of Trent University, Peterborough. There were several dream winters in Churchill Northern Studies Center, Churchill, Manitoba. This is where one of my excuses for doing thesis for so long is grounded. With personnel and surroundings like those in CNSC you just want to do it again. Here should go a complete list of people that made those expeditions so special. I can't help but mention Qiang Huang and Roger Voloshin although anybody from that list is well worth mentioning. My colleagues from "Zephyr North", Burlington, deserve special thanks. I vii learned a lot from collaboration with Paul Stalker and Jim Salmon. It is Dr. Jim Salmon who persuaded me to listen to my supervisor Professor Taylor and return to York University to complete my thesis. As usual, my family and friends stand by me, support me on the bumpy road of my career no matter what. vin Table of Contents Abstract iv Acknowledgements vi Table of Contents ix List of Tables xiii List of Figures xv 1 Introduction 1 1.1 Snow in a geophysical context 2 1.1.1 Blowing Snow 5 1.1.2 Threshold velocity 8 1.1.3 Snow particle size distribution in blowing snow events .... 11 1.2 Gauges to measure snow transport 15 1.3 Objectives of the study 19 ix 2 On-ice stage of the Canadian Arctic Shelf Exchange Study exper­ iment in January - May of 2004 (CASES04) 22 2.1 Introduction 22 2.2 Meteorological towers absolute and relative locations 25 2.3 Instrumentation details 26 2.3.1 Wind measuring devices 33 2.3.2 Temperature/Relative Humidity sensors 35 2.3.3 Snow Depth Ranger 36 2.3.4 Visibility Sensors 37 2.3.5 FlowCapt anemo-driftometer 40 2.3.6 ZEBRA Field Mill 40 2.3.7 Digital Imaging 43 2.3.8 Particle Counters 44 2.3.9 Snow Depth, Density and Salinity 47 2.3.10 Snow Traps 49 3 Snow and its transport in CASES04 51 3.1 Introduction 51 3.2 Snow density 54 3.2.1 Density of surface snow moved by wind 56 x 3.2.2 Surface snow density 59 3.2.3 Density distribution within snow pack 64 3.2.4 Pockets of faceted crystals within snow pack 66 3.3 Salinity of the snow cover 69 3.4 Statistics of the blowing snow events 71 3.5 Threshold wind speed observations and prediction 74 4 Aerodynamic roughness length of a snow covered ice surface based on CASES04 data 80 4.1 Introduction 80 4.2 Site location and profile measuring instrumentation in CASES04 . 83 4.3 Monin-Obukhov Similarity Theory (MOST) form of mean wind speed and temperature profiles 85 4.4 Maximum Likelihood approach to fitting curves to observations . 89 4.5 Fitting data to MOST profiles 93 4.6 Application of the fitting method to artificial profiles 102 4.7 Momentum roughness in CASES04 108 4.8 Influence of snow drift on momentum roughness 115 5 Light beam interruption counter 121 5.1 Basics of individual particles light shadowing detection 122
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