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Environmental Science and Engineering Subseries: Environmental Science Series Editors: R. Allan • U. Förstner • W. Salomons Christoph S. Garbe, Robert A. Handler, Bernd Jähne (Eds.) Transport at the Air-Sea Interface Measurements, Models and Parametrizations With 127 Figures and a CD-ROM Editors: PRIV.-DOZ. DR. C.S. GARBE PROF. DR. B. JÄHNE INTERDISCIPLINARY CENTER FOR SCIENTIFIC COMPUTING UNIVERSITY OF HEIDELBERG IM NEUENHEIMER FELD 368 69120 HEIDELBERG GERMANY AND INSTITUTE OF ENVIRONMENTAL PHYSICS UNIVERSITY OF HEIDELBERG IM NEUENHEIMER FELD 229 69120 HEIDELBERG GERMANY E-mail: Christoph.Garbe@iwr.uni-heidelberg.de Bernd.Jaehne@iwr.uni-heidelberg.de DR. R.A. HANDLER Naval Research Laboratory 4555 Overlook Avenue SW Washington DC 20375 USA E-mail: robert.handler@nrl.navy.mil ISSN 1863-5520 ISBN 10 3-540-36904-x Springer Berlin Heidelberg New York ISBN 13 978-3-540-36904-2 Springer Berlin Heidelberg New York Library of Congress Control Number: 2007931824 This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer-Verlag. Violations are liable to prosecution under the German Copyright Law. Springer is a part of Springer Science+Business Media springeronline.com © Springer-Verlag Berlin Heidelberg 2007 The use of general descriptive names, registered names, trademarks, etc., in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Cover design: deblik, Berlin Production: A. Oelschläger Typesetting: Camera-ready by the Editors Printed on acid-free paper 30 2132 AO 543210 Preface The sea surface represents the interface between the ocean and the atmosphere. As the interface is approached from either the atmospheric or ocean side, the transport mechanisms are shifted from turbulent to diffusive diffusion. Hence, the viscous boundary layers at both sides of the water surface represent the major resistance to the transport of energy, mass, and impulse between atmosphere and ocean. This has implications for the composition of the atmosphere and has gained importance especially for radiatively (climate)-active gases such as CO2, CH4, N2O, and DMS. But also, the transport of gases across the interface is significant for the fate and atmospheric marine budgets of many man-made pollutants, in particular volatile organic compounds and mercury. The two key variables which are required for the determination of the gas exchange fluxes are the partial pressure difference of the considered gas at the sea surface, and the gas exchange transfer velocity k. Partial pressure differences are either obtained from measurements in the surface water and in the atmosphere or from biogeochemical models. Whereas our knowledge about the partial pressure distribution, in particular for CO2, has increased considerably during the past years, the choice of an appropriate transfer velocity is still a matter of controversy. This is because the transport mechanisms across the free, wind-driven water surface are still only known superficially. This is not surprising because both the experimental investigation as well as the modeling is very challenging. Experimental techniques and modeling efforts have evolved separately with little quantitative comparisons. Recently, refined measurement techniques have advanced which allow researchers to gain novel insights into the boundary layer processes. Likewise, computer simulations have improved significantly both in terms of resolution and model complexity. This has made it feasible to compare model output of realistic boundary conditions to actual measurements. Through these comparisons, models can be verified, leading to a deepening of our knowledge of the transport of energy and mass between ocean and atmosphere. Only by linking experimental measurements with computer models can our understanding of air-sea interactions be enhanced. In turn, through insights into the underlying transport processes, physically sound parameterizations can be found. Better parameterizations are needed in order to improve global models of our climate and predict climatic change. In order to bridge the gap between current models and measurements as well as spark new ideas for novel simulation and experimental efforts, an “International Workshop on Transport at the Air-Sea Interface” was organized by the editors of this volume. The focus of the workshop was on small-scale processes directly at the interface. The workshop took place at the University of Heidelberg from September 6–8, 2006. Leading scientists from around the world came together and focused on different aspects of the transport across the air-water interface. The current state-of-the-art research was presented, and current and future research interests and problems were discussed. The program of the workshop is listed after this preface. This volume contains peer-reviewed, extended, and updated versions of selected talks that also reflect the discussions during the workshop. The editors cordially thank all reviewers for their detailed responses and their efforts to improve the quality of the papers. Heidelberg, April 2007 Christoph Garbe Robert Handler Bernd Jähne Preface VII Contributions to “International Workshop on Transport” at the Air-Sea Interface Session 1: Shear-Free Surface Herlina Turbulent gas flux measurements near the air-water interface in a grid-stirred tank Evan Variano, Edwin A. Cowen Quantitative imaging of CO2 transfer at an unsheared free surface Aldo Tamburrino, Claudius Aravena, John S. Gulliver Visualization of 2-D divergence on the free surface and its relation to gas transfer Session 2: Small Scale Processes Patrick Rosendahl Modelling the influence of small-scale processes in the upper water layer on air-sea CO2 exchange Martin Gade Microwave remote sensing of small-scale features at the water surface that influence air-sea CO2 exchange Alastair D. Jenkins The interaction of ocean surface processes, waves, and turbulence in the adjacent boundary layers Session 3: Gas Exchange Gerhard Peters Estimation of "small" surface fluxes by eddy covariance Achim Falkenroth, Alexandra Herzog, Bernd Jähne Visualization of concentration fields by oxygen quenching and pH indicators Kai Degreif, Bernd Jähne The Schmidt number dependency of air-sea gas transfer: new results and models Session 4: Heat Transfer Chris Fairall Measurement and Parameterization of Latent heat transfer over the Open Ocean Hannah Linag, Kapil Phadnis, Mohamed Atmane, Christopher Zappa, Mark Loewen, William Asher, Andrew Jessup A laboratory study of passive and active IR techniques to measure heat flux Bernd Jähne, Christopher Popp, Uwe Schimpf, Christoph Garbe Analysis of the heat transfer process across the aqueous heat boundary layer by active thermography: mean transfer velocities and intermittence Christoph S. Garbe, Bernd Jähne Measuring and modeling parameters of heat transfer from surface flow fields by IR image sequence analysis Session 5: Temperature Structure of the Interface Nicholas Scott, Geoffrey Smith, Robert Handler The structure of the surface temperature field at an air-water interface at low to moderate wind speeds Brian Ward Thermometric measurements of the molecular sublayer at the air-water interface Session 6: Wave Breaking Johannes Gemmrich Momentum flux and energy dissipation associated with breaking waves. W.L. Peirson, C. Welch, J.W. Walker, M.L. Banner Understanding the enhancement of air-water interfacial oxygen exchange rate by microscale breaking waves Christopher J. Zappa, Felix A. Tubiana, Wade R. McGillis, J. Bent, Gerrit de Leeuw, Marcel M. Moerman Investigating wave processes important to air-sea fluxes using infrared techniques Session 7: Turbulence Guillemette Caulliez, Richard Dupont, Victor I. Shrira Turbulence generation processes in the wind-driven subsurface water flow Haitao Xu, Nicholas T. Ouellette, Mickaël Bourgoin, Ewe-Wei Saw, Evan Variano, Raymond Shaw and Eberhard Bodenschatz Experimental investigations of turbulent relative dispersion and the spray characteristics of a waterfall Tetsu Hara, John Wendelbo, E. Vaninwegen, Christoph Garbe, Uwe Schimpf, Nelson Frew Estimation of air-sea gas and heat fluxes from infrared imagery based on near surface turbulence models Session 8: Rain David Ho Rain and air-water gas exchange S. Komori, N. Takagaki, R. Saiki, N. Suzuki The effects of raindrops on interfacial turbulence and air-water gas transfer Anne-Kristin Anweiler Lab experiments on the influence of rain on air-sea CO2 exchange Session 9: Parameterizations Sanjoy Banerjee The air water interface: turbulence and scalar exchange Wade McGillis Using meteorological techniques to parameterize processes controlling air-water gas fluxes Rik Wanninkhof The impact of different gas exchange parameterizations on global air-sea CO2 fluxes IX Ключевые слова: e, r, o