Seasonal Snowcovers: Physics, Chemistry, Hydrology

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1 Seasonal Snowcovers: Physics, Chemistry, Hydrology

2 NATO ASI Series Advanced Science Institutes Series A series presenting the results of activities sponsored by the NATO Science Committee, which aims at the dissemination of advanced scientific and technological knowledge, with a view to strengthening links between scientific communities. The series is published by an international board of publishers in conjunction with the NATO Scientific Affairs Division A Life Sciences B Physics C Mathematical and Physical Sciences D Behavioural and Social Sciences E Applied Sciences F Computer and Systems Sciences G Ecological Sciences H Cell Biology Plenum Publishing Corporation London and New York D. Reidel Publishing Company Dordrecht, Boston, Lancaster and Tokyo Martinus Nijhoff Publishers Dordrecht, Boston, Lancaster Springer Verlag Berlin, Heidelberg, New York, London, Paris, and Tokyo Series C: Mathematical and Physical SCiences Vol. 211

Seasonal Snowcovers: Physics, Chemistry, Hydrology edited by H.G.Jones Institut National de la Recherche Scientifique, Universite du Quebec, Ste-Foy, Quebec, Canada and W. J.

3 Seasonal Snowcovers: Physics, Chemistry, Hydrology edited by H.G.Jones Institut National de la Recherche Scientifique, Universite du Quebec, Ste-Foy, Quebec, Canada and W. J. Orvill-e-Thomas Department of Chemistry and Applied Chemistry, University of Salford, Lancashire, U.K. D. Reidel Publishing Company Dordrecht / Boston / Lancaster / Tokyo Published in cooperation with NATO Scientific Affairs Division

4 Proceedings of the NATO Advanced Study Institute on Seasonal Snowcovers: Physics, Chemistry, Hydrology Les Arcs, France July 13-25, 1986 Library of Congress Cataloging in Publication Data NATO Advanced Study Institute on Chemical Dynamics of Seasonal Snowcovers (1986 : Les Arcs, France) Seasonal snowcovers: physics, chemistry, hydrology / edited by H.G. Jones and W.J. Orville-Thomas. p. cm - (NATO ASI series. Series C, Mathematical and physical sciences; vol. 211) "Proceedings of the NATO Advanced Study Institute on Chemical Dynamics of Seasonal Snowcovers, Les Arcs, France, July 13-25, 1986"-T.p. verso. "Published in cooperation with NATO Scientific Affairs Division." Includes index. ISBN-13: e-isbn-13: : / Snow-Congresses. I. Jones, H.G. (H. Gerald), II. Orville-Thomas, W. J., III. North Atlantic Treaty Organization. Scientific Affairs Division. IV. Title. V. Series: NATO ASI series. Series C, Mathematical and physical sciences; no.211. GB N '846--dc CIP Published by D. Reidel Publishing Company P.O. Box 17, 3300 AA Dordrecht, Holland Sold and distributed in the U.S.A. and Canada by Kluwer Academic Publishers, 101 Philip Drive, Assinippi Park, Norwell, MA 02061, U.S.A. I n all other countries, sold and distributed by Kluwer AcademiC Publishers Group, P.O. Box 322, 3300 AH Dordrecht, Holland D. Reidel Publishing Company is a member of the Kluwer Academic Publishers Group All Rights Reserved 1987 by D. Reidel Publishing Company, Dordrecht, Holland. So fico vcr reprint of the hardcover 1 st edition 1987 No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage and retrieval system, without written permission from the copyright owner.

5 TABLE OF CONTENTS Preface ix Paper Snow ~etamorphism S. C. Colbeck and Classification Water Vapor Transport in Snow. A 2-D Simulation of Temperature Gradient Hetamorphism l1ark Christon, Patrick Burns, El1ik Thompson and Richard Sommerfeld Measurement of Snow Grain Properties Robert E. Davis, Jeff Dozier and Ron Perla Experimental Study on Thermal Convection and Grains Picture Analysis Eric Brun, Francois Touvier and Gilles Brunot The Fractionation of Natural Isotopes during Temperature Gradient Hetamorphism of Snow Richard A. Sommerfeld, Irving Friedman and Mark Nilles Avalanche Forecasting and Snow Physics Jerome Lafeuille Wind Transport of Seasonal Snowcovers J. W. Pomeroy and D. H. Hale Note on certain Diurnal Variations in the Albedo of Snow and Ice S. J. Bolsenga Modelling of Snowmelt Rates in a Deciduous Forest A. G. Price Prediction of Snow Density and Temperature Changes within Layers of the Snowpack using a Point Energy and Mass Balance Model Jean Stein, Douglas L. Kane, Marcel Prevost, Richard Barry and Andre P. Plamondon

6 vi TABLE OF CONTENTS Paper Modelling of Water Flow through Snowpacks E. M. Morris Direct Scavenging and Induced Transport of Atmospheric Aerosol by Falling Snow and Ice Crystals J. Podzimek Experimental Protocol for the Chemical Analysis of Snow, Firn and Ice Cores Michel R. Legrand and Robert J. Delmas Review of Snowpack Chemistry Studies D. R. DeWalle Chemical Transformations in a Snowcover at Heissfluhjoch, Switzerland, situated 2500 m.a.s.l. Andreas Sigg, Albrecht Neftel and Fritz ZUrcher The Chemical Evolution of a Seasonal Snowcover at Mid-and-High Altitudes Yves Page Physical and Chemical Factors controlling Gaseous Deposition of SO to Snow R. C. Bales, M. P. Valdez, G. A. Dawson and D. A. Stanley The Contribution of Dry Deposition to Snowpack Acidity in Michigan Steven H. Cadle and Jean Muhlbaier Dasch Wind as a Factor in the Direct Measurement of the Dry Deposition of Acid Pollutants to Snowcovers V. Delmas and H. G. Jones The Removal of Soluble Ions from l1elting Snowpacks T. D. Davies, P. Brimblecombe, M. Tranter, S. Tsiouris, C. E. Vincent, P. Abrahams and 1. L. Blackwood Aspects of the Chemistry of Ice, notably Snow, on Lakes Ttl. Peter Adams and Craig Allan Hethodology for Investigation of Snowmelt Hydrology and Chemistry within an undisturbed Canadian Shield Watershed H. C. English, R.G. Semkin, D. S. Jeffries, P. Ttl. Hazlett and N. H. Foster

7 TABLE OF CONTENTS vii Paper Short term Changes in the Fluxes of Hater and of Dissolved Solutes during Snow-melt P. J. Barry and A. G. Price Chemical Dynamics of Snowcover and Snowmelt in a Boreal Forest H. G. Jones Changes in Streamwater Chemistry during Snowmelt M. Tranter, P. W. Abrahams, I. Blackwood, T. D. Davies, P. Brimblecombe, I. P. Thompson and C. E. Vincent Snowmelt runoff in the Lake Laflamme Experimental Watershed, Quebec: Methodology and Preliminary Results Marcel Prevost, Richard Barry, Jean Stein and Andre P. Plamondon Observations of Snowmelt run-off Pathways on a Slope in a Boreal Forest Environment, Lac Laflamme, Quebec Jean Roberge and Andre P. Plamondon A Comparison of Chemical and Isotopic Hydrograph Separation Richard P. Hooper and Christine A. Shoemaker An Isotopic and Geochemical Study of Seasonal Snowmelt runoff in the Apex River Watershed Milan M. Obradrovic and Michael G. SkI ash Snow Chemistry with particular reference for the Chemical Composition of Snow in Scandinavia E. Gjessing and M. Johannessen Snowcover and Snowmelt Processes studied by means of Environmental Isotopes \~. Stichler Index 727

8 PREFACE In recent years, much concern has been expressed on the deleterious effects that anthropogenic emissions of acidic pollutants have on ecosystems of both industrialized countries and remote areas of the world. In many of these regions, seasonal snowcover is a major factor in the transfer of atmospheric pollutants, either to terrestrial and aquatic ecosystems or to the more permanent reservoirs of glaciers and ice sheets. The recognition of the role that seasonal snowcovers can thus play in the chemical dynamics of whole ecosystems was recently echoed by the Committee on Glaciology of the National Research Council (National Academy of Sciences, National Academy of Engineering and the Institute of Medicine) which recommended that studies on "Impurities in the snowpack, their discharge into runoff, and management of the problem" be rated at the highest prority level (ref. a). It is in this context that the Advanced Research Institute (ASI) brought together scientists active in the fields of snow physics, snow chemistry and snow hydrology. The programme was structured so as to facilitate the exchange of information and ideas on the theories for the chemical evolution of seasonal snowcovers and snowmelt and on the impact of the chemical composition of the meltwaters on the different components of hydrological systems. As a consequence the ASI also attracted participants from potential users of the information that was disseminated; these were particularly concerned with the effects of snowmelt and snowcover on terrestrial biota and those of lakes and streams. This ASI volume reflects the nature of the meeting in content by presenting 12 papers (1-12; the numbers refer to the paper listed in the CONTENT section) on the physics and/or the physical chemistry, 16 papers on the chemistry (13-2S, 30, 31) and 4 papers (26-28) on the hydrology of seasonal snowcovers. The physics group is strongly oriented towards the understanding of the physics behind the changing microstructure of the snowpack (water vapour transport and metamorphism (1,2), the development of techniques to follow microstructure evolution (3-S) and the modelling of the melting of grains as the pack undergoes the phase change to liquid water (9, 10). The papers on.the chemistry of the snowpack encompass both a discussion of processes that influence the distribution of chemical species in the pack (14, 17-19) and in the meltwater (20, 30, 31) and the chemical composition of snowpacks in such specific sites as alpine slopes (ls, 31), forests (22-24) subalpine catchments (2S) and on floating ice covers (21). Although the hydrology papers were fewer in number they relate to two important aspects of the melting of seasonal snowcovers. The first concerns the movement of snowmelt water through the soil horizons (26, 27) whilst the second touches on the techniques to distinguish event water (snowmelt) from "older" water (groundwater) during the spring runoff (28, 29). All of the participants were in accord that, prior to the melt season, there is no foundation for the belief that seasonal snowpacks

9 x PREFACE are conservative. It was emphasized, for example, that in-pack chemical dynamics are not necessarily suppressed below OoC. The mass transfer of water vapour in the pack during the temperature-gradient induced metamorphism of snow grains (1, 2) would suggest that both pollutant aerosols and gases are redistributed within the snow by phoretic effects or simply removed, either by settling to the soil-snow interface or remitted to the atmosphere at the snow-air interface. Evidence was presented, however, to demonstrate that physical processes may not be the only factor influencing the chemical changes in cold snowpacks as the concentration of metastable oxidants (15) in alpine snowcover changes with time. Chemical changes due to the increases from dry deposition to snowcovers of strong-acid anionic pollutants were shown to be generally low (18). Dry deposition of cations, however, can be much higher depending on regional land use and in some cases may be an appreciable source of cations for the neutralization of the hydrogen ion (14, 18). In contrast, chemical changes in wet snow were well documented particularly with regard to the phenomena of the concentration-factor effect and the preferential elution of ions (20) during meltwater discharge from the pack. The theoretical basis for the preferential migration of ions within the wet packs was the subject of some discussion. There was debate as to whether this migration is a result of the original distribution of the ionic species, on and within the ice crystals prior to melt, or the reflection of chemical transformation of these species in the liquid phase during movement down and out of the pack. Results from field and laboratory studies on forest snowpacks_were cited (23, 24) to show in effect that some ionic species (NH 4, NO J ) are depleted during melt due to microbiological activity in the pack. During the discussions several techniques for the study of physical processes in both dry and wet snow in the laboratory and field were presented; field instrumentation for the sampling of snowpacks and meltwaters for chemical analysis was also described. As many seasonal snowcovers contain very low concentrations of pollutants, adequate sampling and preservation techniques of the snow samples in the field have to be applied in order to eliminate any contamination. Equal care has also to be applied to the subsequent chemical analysis (13) or relatively large errors may arise. As a result, the failure in many instances to obtain ionic balances may not be the result of ionic species which are not measured (eg. organic acids) but rather the consequence of faulty analytical techniques. It was generally agreed that, due to the often low concentrations of certain ionic species and to the methodological differences between laboratory studies and field studies of the physics and chemistry of snowpacks, attempts to physically relate the data from such disparate studies should be made with caution. Many participants noted that, in addition to the difficulty of relating the chemical evolution of snowpacks to known physical processes, the problem is further compounded by the heterogeneous nature of snowpack composition. The results of studies on the physical

10 PREFACE xi and/or chemical heterogeneity of snowcover in such sites as forests (23, 24) maritime areas (25) and plains (7) and on ice cover (21) were presented. They demonstrated how other processes such as wind distribution (19), deposition of organic debris (24) and lake-ice fracturing (21) can be dominant factors in the control of the distribution of chemical species in snowcovers while in-pack pipeflow and lateral movement of me1twaters (22) can considerably alter the chemical composition of snowpack discharge. The subsequent flux of ionic species from the pack by meltwater discharge and infiltration through the soil horizons to the surface and subsurface reservoirs of watersheds was discussed at length. The concentration effect in the meltwater discharge from the pack is rapidly attenuated on contact between the infiltrating meltwater and soil (25) and can rarely \be traced through to the surface waters. Field studies (28, 29) sh~w, in effect, that the flux of meltwater through the surface and subsurface horizons is complex and work on stable isotopes, in particular, (~8, 29, 31) demonstrated that appreciable amounts of "old", pre-melt, water may be found in the surface waters even during the period of the maximum runoff in spring. Of the above themes, the one which most commonly arose during discussions on individual papers and during the closing session was the question of the methodology used in field studies. Many participants pointed out that there was too much repetition of the same kind of experimental work. As a result investigators spent more time emphasizing the variability of the snowpack at their study sites rather than trying to discover the causes of the heterogeneous nature of the system e.g. it may, eventually be possible to classify snowpacks by terrain and climatic characteristics. There has been no previous concerted attempt on the part of workers in the science of snow to choose research sites which would be representative of major precipitation/ vegetation zones. There was a suggestion that several model experimental field sites should be designated (arctic, alpine, temperate prairie, forest etc.) and fully instrumented for the study of snow chemistry. The study methodology at each site would be complementary so that inter-site comparisons could be made. It was agreed that the time is opportune for such a project as the forecast changes in climatic conditions, due to the greenhouse effect induced by CO 2 and other gases (ex. CH 4 ) (ref. b), will necessitate the monitoring and comprehension of seasonal snowcover evolution over the next few decades. The sites would also serve for the the acquisition of data that c.ould lead to the development of improved models for snowmelt and, in particular, for the formulation of integrated models of meltwater quality. These models would serve as a base for the management of aquatic systems where snowmelt represents an important contribution to the annual runoff.. In spite of many unanswered questions that we thought "a priori" would have been elucidated and the obvious gaps in the knowledge of the chemical dynamics of snowmelt, the ASI finished on a positive note where it was agreed that our future research must be aimed at building

11 xii PREFACE a more solid theoretical framework for snowpack evolution. More effort should be placed on laboratory work and controlled experiments in the field. Real progress can be accelerated by interdisciplinary studies and better communication between snow scientists in different disciplines working in many different geographical situations; snow chemistry working groups in suitable international associations would be a efficient means of initiating such collaborative ventures. Finally, we would like to express our thanks to all the lecturers and participants who contributed to the success of the ASI; the fact that some papers are not cited in this preface has no bearing whatsoever on the quality of the publication or its pertinence to the ASI, the cited papers simply being chosen as representative of the subject matter that is being referred to in any particular part of the current text. The editors would also like to thank Dr Craig Sinclair, director of the ASI programme, for constant help before and during the meeting. (a) "Snow and Ice Research" An Assessment", Polar Research Board, National Research Council, National Academy Press, Washington, D.C. (1983). (b) Barry, R.G. (1985). The cryosphere and climatic change. In Detecting the climatic effects of increasing carbon dioxide United States Department of Energy. Report ER Editors MacCraken, M.C., and Luther, F.M. W.P. Adams P. Barry H.G. Jones W.J. Orville-Thomas

Structurel Reactivity and Thermochemistry of Ions

Structurel Reactivity and Thermochemistry of Ions NATO ASI Series Advanced Science Institutes Series A series presenting the results of activities sponsored by the NA TO Science Committee, which aims at