Gas diffusion through columnar laboratory sea ice: implications for mixed-layer ventilation of CO₂ in the seasonal ice zone

Gas diffusion through the porous microstructure of sea ice represents a pathway for ocean–atmosphere exchange and for transport of biogenic gases produced within sea ice. We report on the experimental determination of the bulk gas diffusion coefficients, D, for oxygen (O2) and sulphur hexafluoride (SF6) through columnar sea ice under constant ice thickness conditions for ice surface temperatures between -4 and -12 °C. Profiles of SF6 through the ice indicate decreasing gas concentration from the ice/water interface to the ice/air interface, with evidence for solubility partitioning between gas-filled and liquid-filled pore spaces. On average, DSF6 inline image was 1.3 × 10-4 cm2 s-1 (±40%) and DO2 was 3.9 × 10-5 cm2 s-1 (±41%). The preferential partitioning of SF6 to the gas phase, which is the dominant diffusion pathway produced the greater rate of SF6 diffusion. Comparing these estimates of D with an existing estimate of the air–sea gas transfer through leads indicates that ventilation of the mixed layer by diffusion through sea ice may be negligible, compared to air–sea gas exchange through fractures in the ice pack, even when the fraction of open water is less than 1%

Simultaneous use of relaxed eddy accumulation and gradient flux techniques for the measurement of sea-to-air exchange of dimethyl sulphide

The sea-to-air flux of the biogenic volatile sulphur compound dimethyl sulphide was assessed with the relaxed eddy accumulation (REA) and the gradient flux (GF) techniques from a stationary platform in the coastal Atlantic Ocean. Fluxes varied between 2 and 16 µmol m-2 d-1. Fluxes derived from REA were on average 7.1±5.03 µmol m-2 d-1, not significantly different from the average flux of 5.3±2.3 µmol m-2 d-1 derived from GF measurements. Gas transfer velocities were calculated from the fluxes and seawater DMS concentrations. They were within the range of gas transfer rates derived from the commonly used parameterizations that relate gas transfer to wind speed.

Direct measurements of biogenic dimethylsulphide fluxes from the oceans : a synthesis

Author Posting. © National Research Council Canada, 2004. This article is posted here by permission of National Research Council Canada for personal use, not for redistribution. The definitive version was published in Canadian Journal of Fisheries and Aquatic Sciences 61 (2004): 836-844, doi:10.1139/F04-047.This paper provides a brief overview of the state-of-the-art of techniques that are currently used for field measurements of trace gas fluxes and the subsequent derivation of gas transfer rates over the oceans. Special attention is given to the relaxed eddy accumulation (REA) and gradient flux (GF) techniques, which rely on empirical functions thus far mainly validated over land. The universality of these functions and their application at sea have not yet been fully evaluated. New experiments have shown that the emission of dimethylsulphide (DMS) can be measured by the REA and GF techniques. Moreover, these measurements have provided parameterizations of gas exchange rates that are within the range of relationships between wind speed and gas transfer that have recently been derived from eddy correlation (EC) and deliberate tracer measurements. Using DMS as a model, gas is potentially a powerful approach to intercalibrate the REA, GF, and EC techniques, test their applicability in the marine environment, and investigate processes that determine trace gas exchange across the ocean surface

Observations to Quantify Air-Sea Fluxes and Their Role in Climate Variability and Predictability

Flux products quantifying exchanges between ocean and atmosphere are needed for forcing models, understanding ocean dynamics, investigating the ocean’s role in climate, and assessing coupled models. Research experiments are essential to improve flux parameterizations, and longer research deployments are required to sample rare events. Urgently needed technological improvements include longer battery life, more robust sensors and improvement of sensors for humidity, precipitation and direct gas and particle fluxes. A range of different flux products are needed, incorporating data from ships, satellites and models in different combinations and using different methods. All products must be characterized with uncertainty estimates. Dataset validation requires high quality observations from ocean flux reference sites and from ships. The continued development of flux products from satellites provides much-needed sampling. Continual intercomparisons among products and with high quality observations will lead to improved flux datasets, while improvements to the flux data management system would facilitate these intercomparisons

Gas Transfer at Water Surfaces 2010

PrefaceSection 1: Interfacial Turbulence and Air-Water Scalar TransferJ. Hunt, S. Belcher, D. Stretch, S. Sajjadi, J. Clegg [1]S.A. Kitaigorodskii [13]S.A. Kitaigorodskii [29]Y. Toba [38]D. Turney, S. Banerjee [51]J.G. Janzen, H.E. Schulz, G.H. Jirka [65]S. Komori, R. Kurose, N. Takagaki, S. Ohtsubo, K. Iwano, K. Handa, S. Shimada [78]J. Beya, W. Peirson, M. Banner [90]S. Mizuno [104]M. Sanjou, I. Nezu, A. Toda [119]M. Sanjou, I. Nezu, Y. Akiya [129]K. Takehara, Y. Takano, T.G. Etoh [138]G. Caulliez [151]Section 2: Numerical Studies on Interfacial Turbulence and Scalar TransferL.-P. Hung, C.S. Garbe, W.-T. Tsai [165]A. E. Tejada-Martínez, C. Akan, C.E. Grosch [177]W.-T. Tsai, L.-P. Hung [193]P.G. Jayathilake, B.C. Khoo, Zhijun Tan [200]H.E. Schulz, A.L.A. Simões, J.G. Janzen [208]Section 3: Bubble-Mediated Scalar TransferD.P. Nicholson, S.R. Emerson, S. Khatiwala, R.C. Hamme [223]W. Mischler, R. Rocholz, B. Jähne [238]R. Patro, I. Leifer [249]K. Loh, K.B. Cheong, R. Uittenbogaard [262]N. Mori, S. Nakagawa [273]Section 4: Effects of Surfactants and Molecular Diffusivity on Turbulence and Scalar TransferA. Soloviev, S. Matt, M. Gilman, H. Hühnerfuss, B. Haus, D. Jeong, I. Savelyev, M. Donelan [285]S. Matt, A. Fujimura, A. Soloviev, S.H. Rhee [299]P. Vlahos, E.C. Monahan, B.J.Huebert, J.B. Edson [313]K.E. Richter, B. Jähne [322]X. Yan, W.L. Peirson, J.W. Walker, M.L. Banner [333]Section 5: Field MeasurementsP.M. Orton, C.J. Zappa, W.R. McGillis [343]U.Schimpf, L. Nagel, B. Jähne [358]C.L. McNeil, E.A. D'Asaro, J.A. Nystuen [368]D. Turk, B. Petelin, J.W. Book [377]M. Ribas-Ribas, A. Gómez-Parra, J.M. Forja [394]A. Rutgersson, A.-S. Smedman, E. Sahlée [406]H. Pettersson, K. K. Kahma, A. Rutgersson, M. Perttilä [420]Section 6: Global Air-Sea CO2 FluxesR. Wanninkhof, G.-H. Park, D.B. Chelton, C.M. Risien [431]N. Suzuki, S. Komori, M.A. Donelan [445]Y. Suzuki, Y. Toba [452]M.T. Johnson, C. Hughes, T.G. Bell, P.S. Liss [464]Section 7: Advanced Measuring TechniquesO. Tsukamoto, F. Kondo [485]R. Rocholz, S. Wanner, U. Schimpf, B. Jähne [496]B.C.G. Gonzalez, A.W. Lamon, J.G. Janzen, J.R. Campos, H.E. Schulz [507]E. Sahlée, K. Kahma, H. Pettersson, W.M. Drennan [516]D. Kiefhaber, R. Rocholz, G. Balschbach, B. Jähne [524]C.S. Garbe, A. Heinlein [535]Section 8: Environmental Problems Related to Air-Water Scalar TransferW.L. Peirson, G.A. Lee, C. Waite, P. Onesemo, G. Ninaus [545]Y.J. Choi, A. Abe, K. Takahashi [559]Y. Baba, K. Takahashi [571]R. Onishi, K. Takahashi, S. Komori [582][593]Turbulence and wave dynamics across gas-liquid interfacesThe calculation of the gas transfer between the ocean and atmosphereThe influence of wind wave breaking on the dissipation of the turbulent kinetic energy in the upper ocean and its dependence on the stage of wind wave developmentMarvellous self-consistency inherent in wind waves : Its origin and some items related to air-sea transfersNear surface turbulence and its relationship to air-water gas transfer ratesTurbulent gas flux measurements near the air-water interface in an oscillating-grid tankSensible and latent heat transfer across the air-water interface in wind-driven turbulenceRainfall-generated, near-surface turbulenceEffects of the mechanical wave propagating in the wind direction on currents and stresses across the air-water interfaceTurbulent transport in closed basin with wind-induced water wavesPIV measurements of Langumuir circulation generated by wind-induced water wavesStudy of vortices near wind wave surfaces using high-speed video camera and MLSWind wave breaking from micro to macroscaleValidation of Eddy-renewal model by numerical simulationMass transfer at the surface in LES of wind-driven shallow water flow with Langmuir circulationCharacteristics of gas-flux density distribution at the water surfacesNumerical simulation of interfacial mass transfer using the immersed interface methodStatistical approximations in gas-liquid mass transferAn inverse approach to estimate bubble-mediated air-sea gas flux from inert gas measurementsExperimental setup for the investigation of bubble mediated gas exchangeGas transfer velocity of single CO2 bubblesMass transfer across single bubblesAeration of surf zone breaking wavesModification of turbulence at the air-sea interface due to the presence of surfactants and implications for gas exchange. Part I: laboratory experimentModification of turbulence at the air-sea interface due to the presence of surfactants and implications for gas exchange. Part II: numerical simulationsWind-dependence of DMS transfer velocity: Comparison of model with recent southern ocean observationsA laboratory study of the Schmidt number dependency of air-water gas transferOn transitions in the Schmidt number dependency of low solubility gas transfer across air-water interfacesAn autonomous self-orienting catamaran (SOCa) for measuring air-water fluxes and forcingThe 2009 SOPRAN active thermography pilot experiment in the Baltic SeaObservations of air-sea exchange of N2 and O2 during the passage of Hurricane Gustav in the Gulf of Mexico during 2008The effect of high wind Bora events on water pCO2 and CO2 exchange in the coastal Northern AdriaticSeasonal sea-surface CO2 fugacity in the north-eastern shelf of the Gulf of Cádiz (southwest Iberian Peninsula)Including mixed layer convection when determining air-sea CO2 transfer velocityAir-sea carbon dioxide exchange during upwellingImpact of small-scale variability on air-sea CO2 fluxesThe effect of wind variability on the air-sea CO2 gas flux estimationFuture global mapping of air-sea CO2 flux by using wind and wind-wave distribution of CMIP3 multi-model ensembleA Rumsfeldian analysis of uncertainty in air-sea gas exchangeAccurate measurement of air-sea CO2 flux with open-path Eddy-CovarianceCombined Visualization of wind waves and water surface temperatureMicroscopic sensors for oxygen measurement at air-water interfaces and sediment biofilmsDamping of humidity fluctuations in a closed-path systemImproved Optical Instrument for the Measurement of Water Wave Statistics in the FieldFriction Velocity from Active Thermography and Shape AnalysisEvaporation mitigation by storage in rock and sandDevelopment of oil-spill simulation system based on the global ocean-atmosphere modelStructure variation dependence of tropical squall line on the tracer advection scheme in cloud-resolving modelHigh-resolution simulations for turbulent clouds developing over the oceAuthor Inde

Concentração e fluxo de CO2 sobre o reservatório hidrelétrico de Balbina (AM)

The reservoir Balbina (59º 28’ 50w, 1º 53’ 25” S), located near the city of Manaus, Amazonas, in Central Amazônia, Brazil, is the second largest hydroelectric reservoir in an area located in the Amazon Basin. In this reservoir, CO2 measurements were performed at high frequency (10 Hz), CO2 flux with gas analyzer infrared (IRGA) coupled to a floating chamber and meteorological variables with a buoy instrumented to 2 m from the lake surface. The average CO2 concentration was 392 and 426 ppm for the day and night, respectively, and the daily average emission rate was 40.427±24.040 μmol-1.m-2.d-1. The accumulation of CO2 in the lake overnight, beyond respiration, shows to be affected by low wind speeds, waterside convection, physical processes involving high concentrations of CO2 for the surface and the presence of land breeze. The fluxes show no statistically significant difference with the meteorological variables and were considerably lower than a previous study for the same lake. However, the values are in agreement with other studies in Amazonian tropical lakes and other reservoirs. © 2017, ABES - Associacao Brasileira de Engenharia Sanitaria e Ambiental. All rights reserved

A global sea surface carbon observing system: inorganic and organic carbon dynamics in coastal oceans

Coastal environments are an important component of the global carbon cycle, and probably more vulnerable than the open ocean to anthropogenic forcings. Due to strong spatial heterogeneity and temporal variability, carbon flows in coastal environments are poorly constrained. Hence, an integrated, international, and interdisciplinary program of ship-based hydrography, Voluntary Observing Ship (VOS) lines, time-series moorings, floats, gliders, and autonomous surface vessels with sensors for pCO2 and ancillary variables are recommended to better understand present day carbon cycle dynamics, quantify air-sea CO2 fluxes, and determine future long-term trends of CO2 in response to global change forcings (changes in river inputs, in the hydrological cycle, in circulation, sea-ice retreat, expanding oxygen minimum zones, ocean acidification, ?) in the coastal oceans. Integration at the international level is also required for data archiving, management, and synthesis that will require multi-scale approaches including the development of biogeochemical models and use of remotely sensed parameters. The total cost of these observational efforts is estimated at about 50 million US dollars per year