DOCSLIB.ORG

MACROPHYSICAL PROPERTIES and a CLIMATOLOGY of ARCTIC COASTAL FOG in EAST GREENLAND GAËLLE FLORENCE GILSON Bachelor of Science

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
MACROPHYSICAL PROPERTIES and a CLIMATOLOGY of ARCTIC COASTAL FOG in EAST GREENLAND GAËLLE FLORENCE GILSON Bachelor of Science MACROPHYSICAL PROPERTIES AND A CLIMATOLOGY OF ARCTIC COASTAL FOG IN EAST GREENLAND GAËLLE FLORENCE GILSON Bachelor of Science, Université catholique de Louvain, 2008 Master of Science, Université libre de Bruxelles, 2010 A Thesis Submitted to the School of Graduate Studies of the University of Lethbridge in Fulfilment of the Requirements for the Degree DOCTOR OF PHILOSOPHY Department of Geography University of Lethbridge LETHBRIDGE, ALBERTA, CANADA © Gaëlle Florence Gilson, 2018 MACROPHYSICAL PROPERTIES AND A CLIMATOLOGY OF ARCTIC COASTAL FOG IN EAST GREENLAND GAËLLE FLORENCE GILSON Date of Defence: January 26, 2018 Dr. H. Jiskoot Associate Professor Ph.D. Supervisor Dr. C. Hopkinson Professor Ph.D. Thesis Examination Committee Member Dr. M. Letts Professor Ph.D. Thesis Examination Committee Member Dr. J. J. Cassano Associate Professor Ph.D. Thesis Examination Committee Member University of Colorado at Boulder Dr. L. Flanagan Professor Ph.D. Internal External Examiner Department of Biological Sciences Dr. A. Bush Professor Ph.D. External Examiner University of Alberta Edmonton, Alberta Dr. S. Bubel Associate Professor Ph.D. Chair, Thesis Examination Committee DEDICATION This dissertation is dedicated to my grandparents Denise and André, age 91 and 97. iii ABSTRACT Arctic summer fog is a major transportation hazard and has implications for the cryospheric energy balance. In this thesis, the climatology and macrophysical properties of fog along the coast of East Greenland are explored, and local to mesoscale environmental conditions studied to explain regional differences. Using a combination of long-term synoptic weather observations and Integrated Global Radiosonde Archive data, novel automated methods were developed to classify liquid fog thermodynamic structure and calculate fog top elevation. Six fog types were identified; several of which could be associated with advection fog formation and dissipation processes. Temperature inversions during fog were deeper and stronger compared to non-fog conditions. At Low- Arctic locations fog was geometrically thin and occurred below the temperature inversion. Fog was thicker in the High-Arctic, often penetrating the inversion layer. The radiosonde data analysis and automated methods presented are applicable to any synoptic Arctic weather station with present weather codes. iv ACKNOWLEDGEMENTS My PhD journey was a beautiful challenge and experience that would not have been possible without the help and guidance of many individuals. This thesis is the result of support from a wonderful supervisor, encouraging committee members and colleagues, talented scientists I met at conferences, helpful and empathetic academic staff at the University of Lethbridge, and my generous and loving friends and family. The person who undoubtedly contributed the most to my success is my dedicated PhD supervisor Dr. Hester Jiskoot. I am extremely thankful that she offered me the opportunity to conduct my PhD under her supervision and become her first PhD student in the Glaciology & Geoscience Lab. Her trust and wisdom carried me all along my PhD journey. With her scientific rigour, creativity and fairness, Hester is an inspiring model. She helped me develop as an academic thanks to her ongoing constructive feedback on all aspects of my thesis and because she offered me exceptional opportunities such as participating in prestigious graduate courses and international conferences. Under her supervision I learned to develop research ideas, write proposals and scientific manuscripts, and prepare effective presentations for conferences or teaching. Her advice went beyond my graduate programme since I also learned about research ethics and to initiate new research projects in collaboration with other scientists. Besides being a great researcher and supervisor, Hester is also a kind and generous person, who had always had a thought for me on celebration days or when I was recovering from my work-related injury. Lastly, I want to thank Hester for her availability and the considerable amount of time that she spent revising draft chapters of this thesis in great detail. I sincerely hope I will have the opportunity to keep collaborating with her beyond the scope of this thesis. v My supportive PhD supervisory committee has also played a crucial role in the accomplishment of this thesis. Drs. Matthew Letts and Chris Hopkinson are highly acknowledged for their time, ongoing encouragement, guidance and critical feedback throughout the years. Chris was very helpful with feedback on funding proposal writing, and is thanked for giving me the opportunity to teach for him, participate in field work, and learn about observation techniques in hydrology. I would like to thank Matt for giving critical feedback on part of this thesis before submission, as well as for encouraging me to seek specific expertise in Arctic boundary-layer processes. Following his suggestions and supported by Hester, I participated in the Arctic Atmospheric Boundary Layer and Local Climate Processes course at the University Centre in Svalbard (UNIS), which allowed me to gain the background knowledge that I was missing. During that course I had the great opportunity to meet Dr. John Cassano (CIRES), who kindly offered to become my fourth PhD committee member, and who has since provided invaluable feedback on my research. I am extremely grateful for his time, consideration and advice, and feel honoured to have him as co-author on several manuscripts. Additionally, I would like to particularly thank my two external examiners Drs. Larry Flanagan (University of Lethbridge) and Andy Bush (University of Alberta) for their valuable feedback and thorough review of my thesis. During my participation in two international PhD courses and various conferences, I was fortunate to meet scientists from across the world whose expertise have contributed to the development of my research ideas and who helped me grow as an academic. I thank Dr. Hans Oerlemans for leading the 2014 Karthaus Summer School on Ice Sheets and Glaciers in the Climate System, and Dr. Marius Jonassen for allowing me to live the vi exceptional experience of participating in a 2016 UNIS graduate course. Fruitful discussions with Dr. Jakob Abermann (Asiaq) directed part of this work towards microwave radiometer data and opened my mind to creative research ideas. I am also grateful to have crossed paths with Dr. Robert Schemenauer (FogQuest), who is a kind and wise man and respected scientist who I was very happy to meet. Our discussions about academic career and life in general were very enlightening. I would like to especially acknowledge him for introducing me to Dr. Ismail Gultepe, one of the top fog scientists in Canada. Dr. Gultepe generously invested a week of his time to talk about fog processes and to show me his extensive suite of fog measuring instruments, which was a unique experience. In addition, he gave me the opportunity to deliver a department seminar during my visit to Environment and Climate Change Canada, as well as be part of his EGU-2017 session. He is further highly acknowledged for his co-authorship on the Boundary-Layer Meteorology manuscript. In addition, I would like to acknowledge several scientists who I have not had a chance to meet in person, but who provided me with important information for the achievement of this thesis. I thank Dr. Timothy James for providing his time-lapse images that were an invaluable support to complement my radiosonde data analysis. Dr. Andy Rhines (University of Washington, http://www.stochtastic.com/) is acknowledged for sharing his Matlab script to extract radiosonde data. Dr. Michael Tjernström and John Cappelen provided important information regarding field data and fog measurement techniques. During my PhD journey, I received a considerable support from colleagues and academics at the University of Lethbridge. I would like to particularly thank Drs. Phil Bonnaventure and Rob Laird who provided advice about data analysis and statistics, and vii Drs. Shawn Bubel and Stefan Kienzle for contributing to my PhD comprehensive examination. Orrin Hawke, Ben Fox and Tyrell Nielsen, undergraduate students supervised by Hester, are acknowledged for their help in contributing to the development of some of the Matlab scripts for Chapter 2, researching relevant literature on fog microphysics, and retrieving CALIPSO data. The teaching seminars delivered by Dr. Doug Orr were very instructive, and helpful for developing my teaching and presentation skills. I thank Dr. Wesley Van Wychen for providing me with valuable feedback on oral presentations. All other lab mates, particularly Jade Cooley, are acknowledged for their good and productive working atmosphere. I also want to thank all graduate students I had the pleasure to meet during my stay at the University of Lethbridge, including Charmaine, Colin, Gordon, Dave, Shaghayegh, Nima, Marcus, Ashley, Linda and Thais. In addition, I would like to thank Suzanne McIntosh, Dean Rob Wood, Kathy Schrage and all medical staff for their help, support and accommodation following my work-related injury occurring in the early stages of my PhD. I acknowledge my funding agencies for making this project possible. This PhD was supported by an NSERC Discovery Grant to Dr. Hester Jiskoot, an Alberta Innovates Technology Futures Graduate Scholarship, and various University of Lethbridge scholarships and awards. Additional funding was through a Women Scholars Award, Gem and Mineral Federation of Canada Scholarship, LPIRG,
Load more

Recommended publications
  • Thermodynamics
    Copyright© 2004, School of Meteorology, University of Oklahoma. Rev 04/04 Knowledge Expectations for METR 3213 Physical Meteorology I: Thermodynamics Purpose: This document describes the principal concepts, technical skills, and fundamental understanding that all students are expected to possess upon completing METR 3213, Physical Meteorology I: Thermodynamics. Individual instructors may deviate somewhat from the specific topics and order listed here. Pre-requisites: Grade of C or better in MATH 2443, PHYS 2524, METR 2024 (or 2413). Students should have a basic understanding of functions of several variables, partial derivatives, differentials of multivariate functions, line and surface integrals, the basics of state variables such as temperature, pressure, density, and volume, and basic energy concepts prior to starting this course. Goal of the Course: This course introduces the physical processes associated with atmospheric composition, basic radiation and energy concepts, the equation of state, the zeroth, first, and second law of thermodynamics, the thermodynamics of dry and moist atmospheres, thermodynamic diagrams, statics, and atmospheric stability. Topical Knowledge Expectations I. Basic Radiation Principles. • Understand the basic physical concepts of radiative transfer of energy, including radiation characteristics, quantities and units. • Understand the concepts of emission, absorption, and scattering of radiation. • For solar (short-wave) radiation, understand the definition of the albedo and know typical values for different surfaces. Understand the dominant causes of absorption and scattering of solar radiation in the atmosphere. • For long-wave radiation in the atmosphere, understand the important constituents (greenhouse gases) and processes affecting emission and absorption. • Be familiar and work problems using Wien’s Law, Stefan Boltzmann’s Law, and the Inverse Square Law.
    [Show full text]
  • Properties of Diamond Dust Type Ice Crystals Observed in Summer Season at Amundsen-Scott South Pole Station, Antarctica
    180 JournaloftheMeteorological SocietyofJapanVol 57,No.2 Properties of Diamond Dust Type Ice Crystals Observed in Summer Season at Amundsen-Scott South Pole Station, Antarctica By Katsuhiro Kikuchi Department of Geophysics, Hokkaido University, Sapporo and Austin W. Hogan Atmospheric Sciences Research Center, State University of New York at Albany, Albany, New York (Manuscript received 17 November 1977, in revised form 20 May 1978) Abstract The properties of diamond dust type ice crystals were studied from replicas obtained during the 1975 austral summer at South Pole Station, Antarctica. The time variation of the number concentration and shapes of crystals, and the length of the c-axis, the axial ratio (c/a) and the growth mode of columnar type crystal were examined at an air tempera- ture of -35*. Columnar type crystals prevailed, but occasionally more than half the number of ice crystals were plate types, including hexagonal, scalene hexagonal, pentagonal, rhombic, trapezoidal and triangular plates. A time variation of two hour periodicity was found in the number concentration of columnar and plate type crystals. When the number con- centration of columnar type crystals decreased, the length of the c-axis of columnar type crystals also decreased. When the number concentration of columnar type crystals increased, the length of the c-axis of the crystals also increased. There was sufficient water vapor to grow these ice crystals in a supersaturation layer several tens to several hundred meters above the surface. The growth mode of columnar type crystals was different from that of warm and cold region columns reported by Ono (1969). The mass growth rate was 6.0* 10-10 gr*sec-1, and was similar to that obtained in cold room experiments by Mason (1953), but less than that found in field experiments by Isono, et al.
    [Show full text]
  • Vertical Structure of the Atmosphere
    Chapter 5: Vertical structure of the atmosphere 5.1 Sounding of the atmosphere Fig.2.1 indicates that globally temperature decreases with altitude in the troposphere. However, already Fig.4.2 showed that locally the temperature can also stay constant with height (isothermal layer), or even increase (inversion layer). The actual stratification of the atmosphere is highly variable in space and time and is, thus, routinely probed by all national weather services. Generally, this probing consists of launching a radiosonde every 3 to 6 hours. Fig. 5.1: Photo sequence of the launching of a radiosonde on a ship and (on the right) the schematic structure of a radiosonde; La METEO de A à Z; Météo France ISBN/2.234.022096 The balloon is filled with hydrogen. Attached is a parachute to assure a soft landing, an aluminium foil to assure a high radar reflectivity and the actual sonde containing instruments for measuring pressure, temperature and humidity. For a description of the humidity sensor see chapter 3.4.1. Temperature, humidity and pressure are radiotransmitted to the station at the ground, while wind speed and wind direction are derived from telemetric data following the balloon by radar. The vertical profile of the atmosphere is then transferred on thermodynamic diagram papers. An eXample of such a representation can be found in Fig. 5.3. The diagram paper used here is a skew T –log p diagram paper which has a logarithmic aXis of pressure in the vertical and the isotherms are straight lines tilted 45° with respect to the horizontal. Other diagram papers are known also.
    [Show full text]
  • ESCI 241 – Meteorology Lesson 8 - Thermodynamic Diagrams Dr
    ESCI 241 – Meteorology Lesson 8 - Thermodynamic Diagrams Dr. DeCaria References: The Use of the Skew T, Log P Diagram in Analysis And Forecasting, AWS/TR-79/006, U.S. Air Force, Revised 1979 An Introduction to Theoretical Meteorology, Hess GENERAL Thermodynamic diagrams are used to display lines representing the major processes that air can undergo (adiabatic, isobaric, isothermal, pseudo- adiabatic). The simplest thermodynamic diagram would be to use pressure as the y-axis and temperature as the x-axis. The ideal thermodynamic diagram has three important properties The area enclosed by a cyclic process on the diagram is proportional to the work done in that process As many of the process lines as possible be straight (or nearly straight) A large angle (90 ideally) between adiabats and isotherms There are several different types of thermodynamic diagrams, all meeting the above criteria to a greater or lesser extent. They are the Stuve diagram, the emagram, the tephigram, and the skew-T/log p diagram The most commonly used diagram in the U.S. is the Skew-T/log p diagram. The Skew-T diagram is the diagram of choice among the National Weather Service and the military. The Stuve diagram is also sometimes used, though area on a Stuve diagram is not proportional to work. SKEW-T/LOG P DIAGRAM Uses natural log of pressure as the vertical coordinate Since pressure decreases exponentially with height, this means that the vertical coordinate roughly represents altitude. Isotherms, instead of being vertical, are slanted upward to the right. Adiabats are lines that are semi-straight, and slope upward to the left.
    [Show full text]
  • IMS4 Weather Studio
    IMS4 Weather Studio IMS4 Weather Studio is a unique tool for processing, analyzing and graphic presentation of the surface and upper air meteorological, radiation and climatological data. Processing, analyzing and presentation of data of various kinds Meteorological and Standalone application or integrated Supports standard Archive of various settings Pilot Briefing with IMS4 Message switching meteorological saved by individual users and data processing server formats The easy-to-use tool provides convenient way for objective • Topography analysis and displaying of complex data - real-time data • Actual or historical weather data from SYNOP and METAR distribution systems (GTS), SADIS, as well as data outputs from bulletins Numeric Weather Prediction models (NWPs). • NWP model output in GRIB format • Satellite and radar information IMS4 Weather Studio has an inestimable wide use in • SIGWX charts in BUFR format meteorological institutions, forecasting services, and crisis • Lightning locations centers, airports, at climatological research and dispersion • Flight Information Region (FIR) modeling and for many other users. Each layer allows customization by providing a wide choice of Layered maps setting options and the stored customized layer configurations The IMS4 Weather Studio allows easy creating, viewing and can be applicated easily over the maps. printing of the layered maps. The layers include among others: 1 IMS4 Weather Studio Visualization of thermodynamic diagram from local temp IMS4 Weather Studio - GRIB Model (station Prostějov, 1.5.2014 – 00.00, 12.00) Weather data Thermodynamic diagram Weather data can be displayed as numeric values at selected The IMS4 Weather Studio offers a tool to draw thermodynamic locations or grid points, or interpolated in the forms of color diagram.
    [Show full text]
  • 2010GM000935-SE-Pattyn 27..44
    Antarctic Subglacial Lake Discharges Frank Pattyn Laboratoire de Glaciologie, Département des Sciences de la Terre et de l’Environnement Université Libre de Bruxelles, Brussels, Belgium Antarctic subglacial lakes were long time supposed to be relatively closed and stable environments with long residence times and slow circulations. This view has recently been challenged with evidence of active subglacial lake discharge under- neath the Antarctic ice sheet. Satellite altimetry observations witnessed rapid changes in surface elevation across subglacial lakes over periods ranging from several months to more than a year, which were interpreted as subglacial lake discharge and subsequent lake filling, and which seem to be a common and widespread feature. Such discharges are comparable to jökulhlaups and can be modeled that way using the Nye-Röthlisberger theory. Considering the ice at the base of the ice sheet at pressure melting point, subglacial conduits are sustainable over periods of more than a year and over distances of several hundreds of kilo- meters. Coupling of an ice sheet model to a subglacial lake system demonstrated that small changes in surface slope are sufficient to start and sustain episodic subglacial drainage events on decadal time scales. Therefore, lake discharge may well be a common feature of the subglacial hydrological system, influencing the behavior of large ice sheets, especially when subglacial lakes are perched at or near the onset of large outlet glaciers and ice streams. While most of the observed discharge events are relatively small (101–102 m3 sÀ1), evidence for larger subgla- cial discharges is found in ice free areas bordering Antarctica, and witnessing subglacial floods of more than 106 m3 sÀ1 that occurred during the middle Miocene.
    [Show full text]
  • Results of the Third Marine Ice Sheet Model Intercomparison Project (MISMIP+)
    The Cryosphere, 14, 2283–2301, 2020 https://doi.org/10.5194/tc-14-2283-2020 © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License. Results of the third Marine Ice Sheet Model Intercomparison Project (MISMIP+) Stephen L. Cornford1, Helene Seroussi2, Xylar S. Asay-Davis3, G. Hilmar Gudmundsson4, Rob Arthern5, Chris Borstad6, Julia Christmann7, Thiago Dias dos Santos8,9, Johannes Feldmann10, Daniel Goldberg11, Matthew J. Hoffman3, Angelika Humbert7,12, Thomas Kleiner7, Gunter Leguy13, William H. Lipscomb13, Nacho Merino14, Gaël Durand14, Mathieu Morlighem8, David Pollard15, Martin Rückamp7, C. Rosie Williams5, and Hongju Yu8 1Centre for Polar Observation and Modelling, Department of Geography, Swansea University, Swansea, UK 2Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA 3Los Alamos National Laboratory, Los Alamos, NM, USA 4Faculty of Engineering and Environment, Northumbria University, Newcastle, UK 5British Antarctic Survey, Cambridge, UK 6Department of Civil Engineering, Montana State University, Bozeman, MT, USA 7Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany 8Department of Earth System Science, University of California, Irvine, Irvine, CA, USA 9Centro Polar e Climático, Universidade Federal do Rio Grande do Sul, Porto Alegre RS, Brazil 10Potsdam Institute for Climate Impact Research, Potsdam, Germany 11Institute of Geography, University of Edinburgh, Edinburgh, UK 12Faculty of Geosciences, University of Bremen, Bremen, Germany 13Climate and Global Dynamics Laboratory, National Center for Atmospheric Research, Boulder, CO, USA 14Université Grenoble Alpes, CNRS, IRD, IGE, Grenoble, France 15Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA, USA Correspondence: Stephen L. Cornford ([email protected]) Received: 30 December 2019 – Discussion started: 20 January 2020 Revised: 7 May 2020 – Accepted: 21 May 2020 – Published: 21 July 2020 Abstract.
    [Show full text]
  • EGU2010-2038, 2010 EGU General Assembly 2010 © Author(S) 2010
    Geophysical Research Abstracts Vol. 12, EGU2010-2038, 2010 EGU General Assembly 2010 © Author(s) 2010 On the use of the unstable manifold correction in a Picard iteration for the solution of the velocity field in higher-order ice-flow models Bert De Smedt (1), Frank Pattyn (2), and Pieter de Groen (3) (1) Department of Geography and Earth System Science, DGGF-WE, Vrije Universiteit Brussel, Brussels, Belgium ([email protected], +32 (0)262933 78), (2) Laboratoire de Glaciologie, CP 160/03, Faculté de Sciences, Université Libre de Bruxelles, Brussels, Belgium, (3) Department of Mathematics, DWIS-WE, Vrije Universiteit Brussel, Brussels, Belgium Nonlinear iteration schemes are essential for a fast and stable solution of higher-order ice-flow models (HOIFM’s). This topic is gaining momentum as now also ice-sheet models are planned to include higher-order mechanics. In 1996, Hindmarsh and Payne proposed the unstable manifold correction as a way to stabilise the numerical solution of implicit finite-difference discretisations of the time-dependent thickness-evolution equation for ice flow. Since 2002, Pattyn (e.g. Pattyn (2002), Pattyn (2003)) has been using the unstable manifold correction in a Picard iteration to facilitate the solution of the velocity field in HOIFM’s. In more recent work, a variant of the original algorithm was used (e.g. Pattyn and others, 2004). Although this variant usually enables a relatively fast solution, it is theoretically less sound. Using a new 2D HOIFM implementation, we show that, in most cases, there is no need for the unstable manifold correction or its variant in a Picard iteration.
    [Show full text]
  • 5 Atmospheric Stability
    Copyright © 2015 by Roland Stull. Practical Meteorology: An Algebra-based Survey of Atmospheric Science. 5 ATMOSPHERIC STABILITY Contents A sounding is the vertical profile of tempera- ture and other variables in the atmosphere over one Building a Thermo-diagram 119 geographic location. Stability refers to the ability Components 119 of the atmosphere to be turbulent, which you can Pseudoadiabatic Assumption 121 determine from soundings of temperature, humid- Complete Thermo Diagrams 121 ity, and wind. Turbulence and stability vary with Types Of Thermo Diagrams 122 time and place because of the corresponding varia- Emagram 122 tion of the soundings. Stüve & Pseudoadiabatic Diagrams 122 We notice the effects of stability by the wind Skew-T Log-P Diagram 122 gustiness, dispersion of smoke, refraction of light Tephigram 122 Theta-Height (θ-z) Diagrams 122 and sound, strength of thermal updrafts, size of clouds, and intensity of thunderstorms. More on the Skew-T 124 Thermodynamic diagrams have been devised Guide for Quick Identification of Thermo Diagrams 126 to help us plot soundings and determine stability. Thermo-diagram Applications 127 As you gain experience with these diagrams, you Thermodynamic State 128 will find that they become easier to use, and faster Processes 129 than solving the thermodynamic equations. In this An Air Parcel & Its Environment 134 chapter, we first discuss the different types of ther- Soundings 134 modynamic diagrams, and then use them to deter- Buoyant Force 135 mine stability and turbulence. Brunt-Väisälä Frequency 136 Flow Stability 138 Static Stability 138 Dynamic Stability 141 Existence of Turbulence 142 Building a Thermo-diagram Finding Tropopause Height and Mixed-layer Depth 143 Tropopause 143 Components Mixed-Layer 144 In the Water Vapor chapter you learned how to Review 145 compute isohumes and moist adiabats, and in Homework Exercises 145 the Thermodynamics chapter you learned to plot Broaden Knowledge & Comprehension 145 dry adiabats.
    [Show full text]
  • Pattyn2010 EPSL.Pdf
    Earth and Planetary Science Letters 295 (2010) 451–461 Contents lists available at ScienceDirect Earth and Planetary Science Letters journal homepage: www.elsevier.com/locate/epsl Antarctic subglacial conditions inferred from a hybrid ice sheet/ice stream model Frank Pattyn Laboratoire de Glaciologie, Département des Sciences de la Terre et de l'Environnement, CP160/03, Université Libre de Bruxelles, Av. F.D. Roosevelt 50, B-1050 Brussels, Belgium article info abstract Article history: Subglacial conditions of large polar ice sheets remain poorly understood, despite recent advances in satellite Received 15 October 2009 observation. Major uncertainties related to basal conditions, such as the temperature field, are due to an Received in revised form 9 April 2010 insufficient knowledge of geothermal heat flow. Here, a hybrid method is presented that combines numerical Accepted 12 April 2010 modeling of the ice sheet thermodynamics with a priori information using a simple assimilation technique. Available online 18 May 2010 Additional data are essentially vertical temperature profiles measured in the ice sheet at selected spots, as Editor: M.L. Delaney well as the distribution of subglacial lakes. In this way, geothermal heat-flow datasets are improved to yield calculated temperatures in accord with observations in areas where information is available. Results of the Keywords: sensitivity experiments show that 55% of the grounded part of the Antarctic ice sheet is at pressure melting Antarctic ice sheet point. Calculated basal melt rates are approximately 65 Gt year−1, which is 3% of the total surface numerical modeling accumulation. Although these sensitivity experiments exhibit small variations in basal melt rates, the impact subglacial temperature on the ice age of basal layers is quite important.
    [Show full text]
  • Thermodynamic Diagrams
    ESCI 341 – Atmospheric Thermodynamics Lesson 17 – Thermodynamic Diagrams References: Introduction to Theoretical Meteorology, S.L. Hess, 1959 Glossary of Meteorology, AMS, 2000 GENERAL Thermodynamic diagrams are used to graphically display the relation between two of the thermodynamic variables T, V, and p. Process lines represent specific thermodynamic processes on the diagram. Important process lines are Isotherms Isobars Adiabats Pseudoadiabats Isohumes A useful thermodynamic diagram should have the following general properties The area enclosed by a cyclic process should be proportional to the work done during the process. As many of the process lines as possible should be straight. The angle between the isotherms and adiabats should be as close to 90 as possible. CREATING A DIAGRAM WITH AREA PROPORTIONAL TO WORK We’ve previously used the p- diagram. Since work per unit mass is defined as dw pd the area on a p- diagram is proportional to work. The p- diagram is not very useful for meteorologists because The angle between isotherms and adiabats is very small Process lines aren’t very straight Volume is not a convenient thermodynamic variable for meteorology For meteorology it would be useful to have a diagram that uses T and p as the thermodynamic variables. However, we can’t just arbitrarily use T and p and hope that area will be proportional to work. We have to find a way of setting up the axes of our diagram so that area will be proportional to work. Let the variables for the axes be X and Y, and let X and Y be functions of the thermodynamic variables.
    [Show full text]
  • Curriculum Vitae
    Frank Pattyn Home | C.V. | Research | Publications | Cours | Leisure | Contact Curriculum Vitae Personal info • Name: Pattyn • First names: Frank, Jean-Marie, Leon • Birthplace and date: Etterbeek (Belgium), 4 March 1966 • Nationality: Belgian Professional address Laboratoire de Glaciologie Université Libre de Bruxelles CP 160/03 50, av. F.D. Roosevelt, 1050 - Bruxelles Tel.: +32-2-650 28 46 / +32-2-650 22 27 (secr.) Fax.: +32-2-650 22 26 email: [email protected] URL: http://dev.ulb.ac.be/glaciol/index.htm Homepage: http://homepages.ulb.ac.be/~fpattyn Studies • PhD, Vrije Universiteit Brussel, 1998. Title Ph.D. thesis: "Ice-sheet dynamics in eastern Dronning Maud Land, Antarctica". • Doctorate training course certificate, Vrije Universiteit Brussel, 1998. • Graduate (licentiate) in Geography, Vrije Universiteit Brussel, 1986-88. • Title Master Thesis: Een numeriek ijskapmodel van het gletsjersysteem in de Sør Rondane, Dronning Maud Land, Antarctica: een interpretatie van waargenomen gletsjerfluktuaties (A numerical ice-sheet model of the glacier system in the Sør Rondane, Dronning Maud Land, Antarctica: an interpretation of observed glacier fluctuations) . • Undergraduate (candidate) in Geography, Vrije Universiteit Brussel, 1984-86. Professional career • Professor (Professeur) at the Université Libre de Bruxelles , from October 2011 (Chargé de Cours since December 2005). • Visiting Professor at the Université J. Fourier (Laboratoire de Glaciologie et de Géophysique de l'Environnement, LGGE), Grenoble France, May-June 2013. • Visiting professor at the University of Ghent , 2008-2013 (Master course on Basin Modelling, 5%) • Research associate at the Vrije Universiteit Brussel , March 2000 - November 2005. • Lecturer (Maître de Conférence from 2000 and Chargé de Cours (0.1 ETP) from 2004) at the Université Libre de Bruxelles .
    [Show full text]