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Buoyant Convection in Geophysical Flows NATO ASI Series Advanced Science Institute 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 Plenum Publishing Corporation B Physics London and New York C Mathematical and Physical Sciences Kluwer Academic Publishers D Behavioural and Social Sciences Dordrecht, Boston and London E Applied Sciences F Computer and Systems Sciences Springer-Verlag G Ecological Sciences Berlin, Heidelberg, New York, London, H Cell Biology Paris and Tokyo I Global Environment Change PARTNERSHIP SUB-SERIES 1. Disarmament Technologies Kluwer Academic Publishers 2. Environment Springer-Verlag I Kluwer Academic Publishers 3. High Technology Kluwer Academic Publishers 4. Science and Technology Policy Kluwer Academic Publishers 5. Computer Networking Kluwer Academic Publishers The Partnership Sub-Series incorporates activities undertaken in collaboration with NATO's Cooperation Partners, the countries of the CIS and Central and Eastern Europe, in Priority Areas of concern to those countries. NATo-PCO-DATA BASE The electronic index to the NATO ASI Series provides full bibliographical references (with keywords and/or abstracts) to about 50,000 contributions from international scientists published in all sections of the NATO ASI Series. Access to the NATO-PCO-DATA BASE is possible via a CD-ROM "NATO Science and Technology Disk" with user-friendly retrieval software in English, French, and German (©WTV GmbH and DATAWARE Technologies, Inc. 1989). The CD-ROM contains the AGARD Aerospace Data base. The CD-ROM can be ordered through any member of the Board of Publishers or through NATO-PCO, Overijse, Belgium. Series C: Mathematical and Physical Sciences - Vol. 513 Buoyant Convection I• n Geophysical Flows edited by E. J. Plate and E. E. Fedorovich University of Karlsruhe, Germany D. X. Viegas University of COimbra, Portugal and J. C. Wyngaard Pennsylvania State University, U.S.A. SPRINGER-SCIENCE+BUSINESS MEDIA, B.V. Proceedings 01 the NATO Advanced Study Institute on Buoyant Convection in Geophysical Flows Plorzheim, Baden-WOrtlemberg, Germany 17-27 March 1997 A C.I.P. Catalogue record for this book is available from the Library of Congress. ISBN 978-94-010-6125-4 ISBN 978-94-011-5058-3 (eBook) DOI 10.1007/978-94-011-5058-3 Printed on acid-free paper AII Rights Reserved © 1998 Springer Science+Business Media Oordrecht Originally published by Kluwer Academic Publishers in 1998 Softcover reprint of the hardcover 1s t edition 1995 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, includ ing photocopying, record ing or by any information storage and retrieval system, without written permission from the copyright owner. TABLE OF CONTENTS Preface ............................................................ vii E. J. Plate Convective boundary layer: a historical introduction ....................... 1 J. C. Wyngaard Convection viewed from a turbulence perspective ........................ 23 J.C. R. Hunt Eddy dynamics and kinematics of convective turbulenc~ ... . . . . . . . . . . . . . . .. 41 S. Zilitinkevich, A. Grachev, and J. C. R. Hunt Surface frictional processes and non-local heat / mass transfer in the shear-free convective boundary layer .............................. 83 R. B. Stull Convective transport theory and the radix layer ......................... 115 G. S. Golitsyn Convection in viscous and rotating fluids from the viewpoint of the forced flow theory ........................................... 129 R. H. Kase Modeling the oceanic mixed layer and effects of deep convection ........... 157 D. H. Lenschow Observations of clear and cloud-capped convective boundary layers, and techniques for probing them . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 185 C. Kiemle, G. Ehret, K. J. Davis, D. H. Lenschow, and S. P. Oncley Airborne water vapor differential absorption lidar studies of the convective boundary layer .......................................... 207 J. C. Wyngaard Experiment, numerical modeling, numerical simulation, and their roles in the study of convection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 239 R. B. Stull Transilient turbulence theory: a non local description of convection .......... 253 E. Fedorovich Bulk models of the atmospheric convective boundary layer ................ 265 vi C.-H. Moeng Pararneterizations of the convective boundary layer in atmospheric models. . . . . . . ... . .. . . . . .. . . . . . ....... . . . . . ... . . . . . . . . . . . . . ... .. 291 R. N. Meroney Wind tunnel simulation of convective boundary layer phenomena: simulation criteria and operating ranges of laboratory facilities .............. 313 E. Fedorovich and R. Kaiser Wind tunnel model study of turbulence regime in the atmospheric convective boundary layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 327 F. T. M. Nieuwstadt Review of diffusion processes in the convective boundary layer ............ 371 D. X. Viegas Convective processes in forest ftres .................................. 401 C.-H. Moeng Stratocumulus-topped atmospheric planetary boundary layer ............... 421 A. P. Siebesma Shallow cumulus convection ........................................ 441 Index ............................................................. 487 PREFACE Buoyant convection is of interest in many fields of geophysical fluid mechanics, in particular in atmospheric and oceanic dynamics, where buoyancy-driven processes play important roles on a variety of scales of motion. Although the importance of buoyant convection has been recognised for many decades, only recently have the tools become available for effective theoretical and experimental analysis of convective flows. Starting in the 1960s with the pioneering laboratory investigations of atmospheric convection by J. Deardorff, D. Lilly and colleagues and the introduction of bulk models of convectively mixed layers by F. Ball and D. Lilly, convective flows have become a testing ground for numerical models and for sophisticated experimental techniques. The 1960s and 1970s saw a series of field experiments carried out in different countries and aimed at better understanding of the peculiar properties of geophysical convection. The famous Kansas experiment of 1968 allowed fundamental new insights into the nature of convective turbulence in the atmospheric surface layer and has provided a unique data set for two generations of boundary-layer meteorologists. In the 1970s, the first numerical experiments by J. Deardorff on large-eddy simulation of the atmospheric boundary layer raised theoretical studies of geophysical convection to a new level. Today, buoyant convection in geophysical flows is an advanced and still-developing area of research relevant to problems of the natural environment. During the last decade, significant progress has been achieved through experimental studies, both in nature and in the laboratory, and through large-eddy and direct numerical simulations. Coherent structures have been found to playa key role in geophysical boundary layers and in larger-scale atmospheric and hydrospheric circulations driven by buoyant forcing. New aspects of the interaction between convective motions and rotation have recently been discovered in nature and have been investigated numerically. Extensive experimental data have been collected on the role of convection in cloud dynamics and microphysics. New theoretical concepts and approaches have been outlined regarding scaling and parameterizations of physical processes in buoyancy-driven geophysical flows. In several different countries technically advanced laboratory facilities have been constructed for experimental studies of geophysical convection. Efforts to simulate the atmospheric convective boundary layer in a wind tunnel have been made at the Institute of Hydrology and Water Resources Planning (IHW), University of Karlsruhe. The construction of their stratified wind tunnel, which was financed by the German Science Foundation (DFG) and built by M. Rau, was finished in the early 1990s. The first results from the tunnel display a plethora of fascinating flow phenomena closely resembling regimes of turbulent convection in the atmospheric boundary layer. While proceeding with the model studies of buoyant convection, the IHW group established scientific contacts with other research teams over the world dealing with geophysical convection studies. A natural result was the idea of bringing people from these teams together in order to exchange their knowledge and deliver it to the community of young researchers interested in buoyant convection studies. The vii viii Advanced Study Institute (ASI) Programme of the NATO Science Committee was a natural vehicle for implementing this idea. From the beginning the concept of the ASI on Buoyant Convection in Geophysical Flows was supported by a number of experts in the area of convection research and modelling. About twenty of them agreed to contribute to the ASI as invited lecturers. The Programme of the ASI "Buoyant Convection in Geophysical Flows" drafted in 1995-1996 by the editors of this volume (formerly - members of the ASI Organising Committee) was approved and accepted for funding by the NATO Science Committee. The response to our invitation to participate in the ASI was gratifying: we received more than 150 applications from potential participants. Unfortunately, only about 80 could be accepted. The ASI took place during the period from 17 to 27 March 1997 in Pforzheim, a small town at the northern edge of Schwarzwald (Black Forest), Baden-Wiirttemberg, Germany. The programme of the Institute included buoyancy effects in different media: atmosphere, hydrosphere, and the Earth's mantle; on a wide range of scales: from small-scale phenomena in· unstably stratified and convectively mixed layers to deep convection in the atmosphere and the ocean; by different methods of research: field measurements, laboratory simulations, theoretical analysis, and numerical modelling, and within diverse application areas: dispersion of pollutants, parameterization of convection in applied geophysical models, and hazardous phenomena associated with convection. Much of the ASI lecture programme was devoted to fundamentals of convection as a physical phenomenon. We believe that the present volume, which contains focused versions of the invited lectures, will be a useful compendium on the subject for years to come. The volume falls naturally into four parts. The first part contains a collection of introductory lectures focusing on fundamental and phenomenological aspects of geophysical convection, and presenting historical and conceptual overviews of convection studies (chapters by E. J. Plate, J. C. Wyngaard, J. C. R. Hunt, S. S. Zilitinkevich et aI., R. B. Stull, G. S. Golitsyn, R. H. Kiise, D. H. Lenschow, and C. Kiemle et al.). The second part of the volume comprises lecture material on convection modelling and parameterization (chapters by J. C. Wyngaard, R. B. Stull, E. Fedorovich, and C.-H. Moeng). In the third part, the lectures of R. N. Meroney, and E. Fedorovich and R. Kaiser on experimental studies of geophysical convection in the laboratory are presented. Overview of applied aspects of convection studies and convective cloud dynamics is given in the fourth part of the volume (chapters by F. T. M. Nieuwstadt, D. X. Viegas, C.-H. Moeng, and A. P. Siebesma). We hope that the ASI succeeded in filling the gap between fundamental studies of convective geophysical flows and applied modelling of natural phenomena associated with buoyant forcing. Lecturers of the ASI represented both scientific and engineering communities. Their treatment of a variety of the buoyancy-driven natural processes within a common methodological framework should foster links between the theoretical and applied branches of convection research and modelling. ix We are grateful to all lecturers of the ASI for their contributions, especially to those who gave their time to prepare their lecture material for publication in this volume. Thanks are due also to the ASI students, whose active participation in lectures and discussions made the ASI a creative and lively scientific meeting. Our special thanks go to the Local Arrangement Committee members Susanne Rau and Klaus Ammer for their vital help in organising the ASI and in attending to the needs of lecturers and participants. We also extend our gratitude to the administration and personnel of MARITIM Hotel "Goldene Pforte" in Pforzheim, who provided a very comfortable venue for the ASI. We gratefully acknowledge the financial support of the NATO Science Committee. The grant issued by NATO covered the principal portion of the ASI organisation costs. We are also thankful for donations to the ASI by the University of Karlsruhe, Gemeinschaftskernkraftwerk Neckar GmbH, and Neckarwerke Elektrizitatsversorgugs AG. Finally we would like to thank Robert Kolotilo and Dmitrii Mironov for their assistance in preparing the ASI book for publication. Erich Plate, Evgeni Fedorovich, Domingos Viegas, and John Wyngaard March 1998 CONVECTIVE BOUNDARY LAYER: A HISTORICAL INTRODUCTION E. J. PLATE Institute of Hydrology and Water Resources Planning Karlsruhe University Kaiserstrasse 12, 76128 Karlsruhe, Germany Abstract A review is given of early research and concepts on the convective boundary layer, which set the stage for all subsequent developments that have been possible via numerical calculations. The historical development proceeded first with inquiries into the stationary turbulent boundary layer. Starting from concepts developed for aeronautical applications of aerodynamics, early research on the atmospheric boundary layer was concerned almost exclusively with stationary flows. Only in the sixties, was the non-stationarity of the planetary boundary layer considered for the first time, with results that left a number of questions open. The first approaches, which are summarized in this paper, were only concerned with obtaining profiles of mean velocity, mean shear, mean temperature, and mean heat flux, which were governed by conservation equations of mass, momentum, and energy. 1. Introduction As a lower boundary condition for atmospheric motions, the planetary boundary layer is of major interest to meteorological modelling, in particular when one considers processes which take place near the earth's surface, for example in agriculture, where estimates for evaporation and transpiration are needed, or environmental processes, such as emissions from chimneys and exhaust gases from automobiles. Recently, the interest of city planners has also been directed toward such processes, and it is to be expected that environmental issues in city planning will require models which also need parameterizations of the lower part of the atmosphere. The wide interest in the latter issues has been the reason for a previous NATO Advanced Study Institute, conducted by the Institute of Hydrology and Water Resources Planning (Cermak et al. [7]). In response to this interest, scientists all over the world have created a body of knowledge that forms the subject of micrometeorology: the study of the processes in the planetary boundary layer. They started the investigations by considering stationary turbulent boundary layers, which were first considered between 1920 and 1930, notably by G. Taylor, Th. von KarrlUm, and by L. Prandtl and his students, and used basic concepts from the theory of turbulence, as developed by G. Taylor and A. Kolmogorov. Their tool used to overcome the non-linearity of the dominant equations of fluid mechanics was the idea of similarity. The dominant concept which evolved from these EJ. Plate et al. (eds.), Buoyant COlWection in Geophysical Flows, 1-22. © 1998 Kluwer Academic Publishers.
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