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Sample records for air-sea co2 transfer

  1. In situ evaluation of air-sea CO2 gas transfer velocity in an inner estuary using eddy covariance - with a special focus on the importance of using reliable CO2-fluxes

    NASA Astrophysics Data System (ADS)

    Jørgensen, E. T.; Sørensen, L. L.; Jensen, B.; Sejr, M. K.

    2012-04-01

    The air-sea exchange of CO2 or CO2 flux is driven by the difference in the partial pressure of CO2 in the water and the atmosphere (ΔpCO2), the solubility of CO2 (K0) and the gas transfer velocity (k) (Wanninkhof et al., 2009;Weiss, 1974) . ΔpCO2 and K0 are determined with relatively high precision and it is estimated that the biggest uncertainty when modelling the air-sea flux is the parameterization of k. As an example; the estimated global air-sea flux increases by 70 % when using the parameterization by Wanninkhof and McGillis (1999) instead of Wanninkhof (1992) (Rutgersson et al., 2008). In coastal areas the uncertainty is even higher and only few studies have focused on determining transfer velocity for the coastal waters and even fewer on estuaries (Borges et al., 2004;Rutgersson et al., 2008). The transfer velocity (k600) of CO2 in the inner estuary of Roskilde Fjord, Denmark was investigated using eddy covariance CO2 fluxes (ECM) and directly measured ΔpCO2 during May and June 2010. The data was strictly sorted to heighten the certainty of the results and the outcome was; DS1; using only ECM, and DS2; including the inertial dissipation method (IDM). The inner part of Roskilde Fjord showed to be a very biological active CO2 sink and preliminary results showed that the average k600 was more than 10 times higher than transfer velocities from similar studies of other coastal areas. The much higher transfer velocities were estimated to be caused by the greater fetch and shallower water in Roskilde Fjord, which indicated that turbulence in both air and water influence k600. The wind speed parameterization of k600 using DS1 showed some scatter but when including IDM the r2 of DS2 reached 0.93 with an exponential parameterization, where U10 was based on the Businger-Dyer relationships using friction velocity and atmospheric stability. This indicates that some of the uncertainties coupled with CO2 fluxes calculated by the ECM are removed when including the IDM.

  2. Effect of gas-transfer velocity parameterization choice on air-sea CO2 fluxes in the North Atlantic Ocean and the European Arctic

    NASA Astrophysics Data System (ADS)

    Wrobel, Iwona; Piskozub, Jacek

    2016-09-01

    The oceanic sink of carbon dioxide (CO2) is an important part of the global carbon budget. Understanding uncertainties in the calculation of this net flux into the ocean is crucial for climate research. One of the sources of the uncertainty within this calculation is the parameterization chosen for the CO2 gas-transfer velocity. We used a recently developed software toolbox, called the FluxEngine (Shutler et al., 2016), to estimate the monthly air-sea CO2 fluxes for the extratropical North Atlantic Ocean, including the European Arctic, and for the global ocean using several published quadratic and cubic wind speed parameterizations of the gas-transfer velocity. The aim of the study is to constrain the uncertainty caused by the choice of parameterization in the North Atlantic Ocean. This region is a large oceanic sink of CO2, and it is also a region characterized by strong winds, especially in winter but with good in situ data coverage. We show that the uncertainty in the parameterization is smaller in the North Atlantic Ocean and the Arctic than in the global ocean. It is as little as 5 % in the North Atlantic and 4 % in the European Arctic, in comparison to 9 % for the global ocean when restricted to parameterizations with quadratic wind dependence. This uncertainty becomes 46, 44, and 65 %, respectively, when all parameterizations are considered. We suggest that this smaller uncertainty (5 and 4 %) is caused by a combination of higher than global average wind speeds in the North Atlantic (> 7 ms-1) and lack of any seasonal changes in the direction of the flux direction within most of the region. We also compare the impact of using two different in situ pCO2 data sets (Takahashi et al. (2009) and Surface Ocean CO2 Atlas (SOCAT) v1.5 and v2.0, for the flux calculation. The annual fluxes using the two data sets differ by 8 % in the North Atlantic and 19 % in the European Arctic. The seasonal fluxes in the Arctic computed from the two data sets disagree with each

  3. Temporal variability of air-sea CO2 exchange in a low-emission estuary

    NASA Astrophysics Data System (ADS)

    Mørk, Eva Thorborg; Sejr, Mikael Kristian; Stæhr, Peter Anton; Sørensen, Lise Lotte

    2016-07-01

    There is the need for further study of whether global estimates of air-sea CO2 exchange in estuarine systems capture the relevant temporal variability and, as such, the temporal variability of bulk parameterized and directly measured CO2 fluxes was investigated in the Danish estuary, Roskilde Fjord. The air-sea CO2 fluxes showed large temporal variability across seasons and between days and that more than 30% of the net CO2 emission in 2013 was a result of two large fall and winter storms. The diurnal variability of ΔpCO2 was up to 400 during summer changing the estuary from a source to a sink of CO2 within the day. Across seasons the system was suggested to change from a sink of atmospheric CO2 during spring to near neutral during summer and later to a source of atmospheric CO2 during fall. Results indicated that Roskilde Fjord was an annual low-emission estuary, with an estimated bulk parameterized release of 3.9 ± 8.7 mol CO2 m-2 y-1 during 2012-2013. It was suggested that the production-respiration balance leading to the low annual emission in Roskilde Fjord, was caused by the shallow depth, long residence time and high water quality in the estuary. In the data analysis the eddy covariance CO2 flux samples were filtered according to the H2Osbnd CO2 cross-sensitivity assessment suggested by Landwehr et al. (2014). This filtering reduced episodes of contradicting directions between measured and bulk parameterized air-sea CO2 exchanges and changed the net air-sea CO2 exchange from an uptake to a release. The CO2 gas transfer velocity was calculated from directly measured CO2 fluxes and ΔpCO2 and agreed to previous observations and parameterizations.

  4. Wintertime CO2 fluxes in an Arctic polynya using eddy covariance: Evidence for enhanced air-sea gas transfer during ice formation

    NASA Astrophysics Data System (ADS)

    Else, B. G. T.; Papakyriakou, T. N.; Galley, R. J.; Drennan, W. M.; Miller, L. A.; Thomas, H.

    2011-09-01

    Between Nov. 1 2007 and Jan. 31 2008, we calculated the air-sea flux of CO2, sensible heat, and water vapor in an Arctic polynya system (Amundsen Gulf, Canada) using eddy covariance equipment deployed on the research icebreaker CCGS Amundsen. During this time period, Amundsen Gulf was a dynamic sea ice environment composed primarily of first year ice with open water coverage varying between 1-14%. In all cases where measurements were influenced by open water we measured CO2 fluxes that were 1-2 orders of magnitude higher than those expected under similar conditions in the open ocean. Fluxes were typically directed toward the water surface with a mean flux of -4.88 μmol m-2 s-1 and a maximum of -27.95 μmol m-2 s-1. One case of rapid outgassing (mean value +2.10 μmol m-2 s-1) was also observed. The consistent patten of enhanced gas exchange over open water allows us to hypothesize that high water-side turbulence is the main cause of these events. Modification of the physical and chemical properties of the surface seawater by cooling and brine rejection may also play a role. A rough calculation using an estimate of open water coverage suggests that the contribution of these events to the annual regional air-sea CO2 exchange budget may make the winter months as important as the open water months. Although high, the uptake of CO2 fits within mixed layer dissolved inorganic carbon budgets derived for the region by other investigators.

  5. Air-sea transfer of gas phase controlled compounds

    NASA Astrophysics Data System (ADS)

    Yang, M.; Bell, T. G.; Blomquist, B. W.; Fairall, C. W.; Brooks, I. M.; Nightingale, P. D.

    2016-05-01

    Gases in the atmosphere/ocean have solubility that spans several orders of magnitude. Resistance in the molecular sublayer on the waterside limits the air-sea exchange of sparingly soluble gases such as SF6 and CO2. In contrast, both aerodynamic and molecular diffusive resistances on the airside limit the exchange of highly soluble gases (as well as heat). Here we present direct measurements of air-sea methanol and acetone transfer from two open cruises: the Atlantic Meridional Transect in 2012 and the High Wind Gas Exchange Study in 2013. The transfer of the highly soluble methanol is essentially completely airside controlled, while the less soluble acetone is subject to both airside and waterside resistances. Both compounds were measured concurrently using a proton-transfer-reaction mass spectrometer, with their fluxes quantified by the eddy covariance method. Up to a wind speed of 15 m s-1, observed air-sea transfer velocities of these two gases are largely consistent with the expected near linear wind speed dependence. Measured acetone transfer velocity is ∼30% lower than that of methanol, which is primarily due to the lower solubility of acetone. From this difference we estimate the “zero bubble” waterside transfer velocity, which agrees fairly well with interfacial gas transfer velocities predicted by the COARE model. At wind speeds above 15 m s-1, the transfer velocities of both compounds are lower than expected in the mean. Air-sea transfer of sensible heat (also airside controlled) also appears to be reduced at wind speeds over 20 m s-1. During these conditions, large waves and abundant whitecaps generate large amounts of sea spray, which is predicted to alter heat transfer and could also affect the air-sea exchange of soluble trace gases. We make an order of magnitude estimate for the impacts of sea spray on air-sea methanol transfer.

  6. Annual and seasonal fCO2 and air-sea CO2 fluxes in the Barents Sea

    NASA Astrophysics Data System (ADS)

    Lauvset, S. K.; Chierici, M.; Counillon, F.; Omar, A.; Nondal, G.; Johannessen, T.; Olsen, A.

    2013-03-01

    The Barents Sea is the strongest CO2 sink in the Arctic region, yet estimates of the air-sea CO2 flux in this area show a large span reflecting uncertainty as well as significant variability both seasonally and regionally. Here we use a previously unpublished data set of seawater CO2 fugacity (fCO2), and map these data over the western Barents Sea through multivariable linear regressions with SeaWiFS/MODIS remote sensing and TOPAZ model data fields. We find that two algorithms are necessary in order to cover the full seasonal cycle, mainly because not all proxy variables are available for the entire year, and because variability in fCO2 is driven by different mechanisms in summer and winter. A comprehensive skill assessment indicates that there is a good overall correspondence between observations and predictions. The algorithms are also validated using two independent data sets, with good results. The gridded fCO2 fields reveal tight links between water mass distribution and fCO2 in all months, and particularly in winter. The seasonal cycle show peaks in the total air-sea CO2 influx in May and September, caused by respectively biological drawdown of CO2 and low sea ice concentration leaving a large open water area. For 2007 the annual average air-sea CO2 flux is - 48 ± 5 gC m- 2, which is comparable to previous estimates.

  7. Controls on air-sea CO2 flux in the Southern Ocean east of Australia

    NASA Astrophysics Data System (ADS)

    Ayers, J.; Strutton, P. G.

    2014-12-01

    The temperate latitudes of the world oceans (~30-50° north and south) are strong sinks for atmospheric CO2 on a mean annual basis. Due to sparse data, the Southern Ocean is the least understood of these CO2 sink regions, with estimates of the annual air-sea CO2 flux varying by as much as 100%, depending upon the calculation method. This work investigates processes regulating air-sea CO2 flux in the Southern Ocean, with a focus on the Pacific sector east of Australia. We quantify the effects of temperature, biological drawdown, and the large-scale general circulation on seawater pCO2 on seasonal and annual timescales, and discuss the balance of these forcings. We expressly consider the impact of the general circulation on the air-sea CO2 flux, which we showed in a previous study to determine the location of the North Pacific carbon sink region. Worldwide, the regions of strong atmospheric CO2 uptake are all located in deep western boundary currents and their extensions, suggesting a larger role for the general circulation in forcing these sinks than is currently acknowledged or understood. Understanding the processes regulating air-sea CO2 flux in the Southern Ocean is critical for predicting how this gas exchange will change in the future.

  8. Narrowing the spread in CMIP5 model projections of air-sea CO2 fluxes

    PubMed Central

    Wang, Lei; Huang, Jianbin; Luo, Yong; Zhao, Zongci

    2016-01-01

    Large spread appears in the projection of air-sea CO2 fluxes using the latest simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5). Here, two methods are applied to narrow this spread in 13 CMIP5 models. One method involves model selection based on the ability of models to reproduce the observed air-sea CO2 fluxes from 1980 to 2005. The other method involves constrained estimation based on the strong relationship between the historical and future air-sea CO2 fluxes. The estimated spread of the projected air-sea CO2 fluxes is effectively reduced by using these two approaches. These two approaches also show great agreement in the global ocean and three regional oceans of the equatorial Pacific Ocean, the North Atlantic Ocean and the Southern Ocean, including the average state and evolution characteristics. Based on the projections of the two approaches, the global ocean carbon uptake will increase in the first half of the 21st century then remain relatively stable and is projected to be 3.68–4.57 PgC/yr at the end of 21st century. The projections indicate that the increase in the CO2 uptake by the oceans will cease at the year of approximately 2070. PMID:27892473

  9. Direct measurements of air-sea CO2 exchange over a coral reef

    NASA Astrophysics Data System (ADS)

    McGowan, Hamish A.; MacKellar, Mellissa C.; Gray, Michael A.

    2016-05-01

    Quantification of CO2 exchange with the atmosphere over coral reefs has relied on microscale measurements of pCO2 gradients across the air-sea interfacial boundary; shipboard measurements of air-sea CO2 exchange over adjacent ocean inferred to represent over reef processes or ecosystem productivity modeling. Here we present by way of case study the first direct measurements of air-sea CO2 exchange over a coral reef made using the eddy covariance method. Research was conducted during the summer monsoon over a lagoonal platform reef in the southern Great Barrier Reef, Australia. Results show the reef flat to be a net source of CO2 to the atmosphere of similar magnitude as coastal lakes, while adjacent shallow and deep lagoons were net sinks as was the surrounding ocean. This heterogeneity in CO2 exchange with the atmosphere confirms need for spatially representative direct measurements of CO2 over coral reefs to accurately quantify their role in atmospheric carbon budgets.

  10. Air--Sea CO2 Cycling in the Southeastern Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Else, Brent Gordon Thomas

    During the fourth International Polar Year, an interdisciplinary study was conducted to examine the couplings between sea ice, ocean, atmosphere, and ecosystem in the southeastern Beaufort Sea. This thesis examines components of the system that control the air-sea exchange of carbon dioxide. Using eddy covariance measurements, we found enhanced CO2 exchange associated with new ice formation in winter flaw leads. This exchange was typically directed towards the surface, although we also measured one instance of outgassing. Sea surface dissolved CO2 measurements (pCO 2sw) in Amundsen Gulf showed significant undersaturation with respect to the atmosphere at freeze-up, followed by a slow increase over the winter until spring phytoplankton blooms caused strong undersaturation at break-up. Over the summer, pCO2sw increased until becoming slightly supersaturated due to surface warming. Along the southern margins of Amundsen Gulf and on the Mackenzie Shelf we found pCO2sw supersaturations in the fall due to wind-driven coastal upwelling. In the spring, this upwelling occurred along the landfast ice edges of Amundsen Gulf. By combining observations of enhanced winter gas exchange with observations of pCO 2sw in Amundsen Gulf, we derived an annual budget of air-sea CO2 exchange for the region. This exercise showed that uptake through the winter season was as important as the open water season, making the overall annual uptake of CO2 about double what had previously been calculated. Prior to this work, the prevailing paradigm of airsea CO2 cycling in Arctic polynya regions posited that strong CO2 absorption occurs in the open water seasons, and that a potential outgassing during the winter is inhibited by the sea ice cover. As a new paradigm, we propose that the spatial and temporal variability of many processes---including phytoplankton blooms, sea surface temperature and salinity changes, upwelling, river input, continental shelf processes, and the potential for high rates

  11. Mesoscale modulation of air-sea CO2 flux in Drake Passage

    NASA Astrophysics Data System (ADS)

    Song, Hajoon; Marshall, John; Munro, David R.; Dutkiewicz, Stephanie; Sweeney, Colm; McGillicuddy, D. J.; Hausmann, Ute

    2016-09-01

    We investigate the role of mesoscale eddies in modulating air-sea CO2 flux and associated biogeochemical fields in Drake Passage using in situ observations and an eddy-resolving numerical model. Both observations and model show a negative correlation between temperature and partial pressure of CO2 (pCO2) anomalies at the sea surface in austral summer, indicating that warm/cold anticyclonic/cyclonic eddies take up more/less CO2. In austral winter, in contrast, relationships are reversed: warm/cold anticyclonic/cyclonic eddies are characterized by a positive/negative pCO2 anomaly and more/less CO2 outgassing. It is argued that DIC-driven effects on pCO2 are greater than temperature effects in austral summer, leading to a negative correlation. In austral winter, however, the reverse is true. An eddy-centric analysis of the model solution reveals that nitrate and iron respond differently to the same vertical mixing: vertical mixing has a greater impact on iron because its normalized vertical gradient at the base of the surface mixed layer is an order of magnitude greater than that of nitrate.

  12. Influence of precipitation on the CO2 air-sea flux, an eddy covariance field study

    NASA Astrophysics Data System (ADS)

    Zavarsky, Alexander; Steinhoff, Tobias; Marandino, Christa

    2016-04-01

    During the SPACES-OASIS cruise (July-August 2015) from Durban, SA to Male, MV direct fluxes of CO2 and dimethyl sulfide (DMS) were measured using the eddy covariance (EC) technique. The cruise covered areas of sources and sinks for atmospheric CO2, where the bulk concentration gradient measurements resembled the Takahashi (2009) climatology. Most of the time, bulk CO2 fluxes (F=k* [cwater-cair]), calculated with the parametrization (k) by Nightingale et al. 2000, were in general agreement with direct EC measurements. However, during heavy rain events, the directly measured CO2 fluxes were 4 times higher than predicted. It has been previously described that rain influences the k parametrization of air-sea gas exchange, but this alone cannot explain the measured discrepancy. There is evidence that freshwater input and a change in the carbonate chemistry causes the water side concentration of ?c=cwater-cair to decrease. Unfortunately this cannot be detected by most bulk measurement systems. Using the flux measurements of an additional gas like DMS, this rain influence can be evaluated as DMS does not react to changes in the carbonate system and has a different solubility. A pending question is if the enhanced flux of CO2 in the ocean is sequestered into the ocean mixed layer and below. This question will be tackled using the GOTM model to understand the implications for the global carbon cycle.

  13. Air-sea CO2 flux pattern along the southern Bay of Bengal waters

    NASA Astrophysics Data System (ADS)

    Shanthi, R.; Poornima, D.; Naveen, M.; Thangaradjou, T.; Choudhury, S. B.; Rao, K. H.; Dadhwal, V. K.

    2016-12-01

    Physico-chemical observations made from January 2013 to March 2015 in coastal waters of the southwest Bay of Bengal show pronounced seasonal variation in physico-chemical parameters including total alkalinity (TA: 1927.390-4088.642 μmol kg-1), chlorophyll (0.13-19.41 μg l-1) and also calculated dissolved inorganic carbon (DIC: 1574.219-3790.954 μmol kg-1), partial pressure of carbon dioxide (pCO2: 155.520-1488.607 μatm) and air-sea CO2 flux (FCO2: -4.808 to 11.255 mmol Cm-2 d-1). Most of the physical parameters are at their maximum during summer due to the increased solar radiation at cloud free conditions, less or no riverine inputs, and lack of vertical mixing of water column which leads to the lowest nutrients concentration, dissolved oxygen (DO), biological production, pCO2 and negative flux of CO2 to the atmosphere. Chlorophyll and DO concentrations enhanced due to increased nutrients during premonsoon and monsoon season due to the vertical mixing of water column driven by the strong winds and external inputs at respective seasons. The constant positive loading of nutrients, TA, DIC, chlorophyll, pCO2 and FCO2 against atmospheric temperature (AT), lux, sea surface temperature (SST), pH and salinity observed in principal component analysis (PCA) suggested that physical and biological parameters play vital role in the seasonal distribution of pCO2 along the southwest Bay of Bengal. The annual variability of CO2 flux clearly depicted that the southwest Bay of Bengal switch from sink (2013) to source status in the recent years (2014 and 2015) and it act as significant source of CO2 to the atmosphere with a mean flux of 0.204 ± 1.449 mmol Cm-2 d-1.

  14. Air-sea CO 2 fluxes in the Caribbean Sea from 2002-2004

    NASA Astrophysics Data System (ADS)

    Wanninkhof, Rik; Olsen, Are; Triñanes, Joaquin

    2007-06-01

    Air-sea fluxes in the Caribbean Sea are presented based on measurements of partial pressure of CO 2 in surface seawater, pCO 2sw, from an automated system onboard the cruise ship Explorer of the Seas for 2002 through 2004. The pCO 2sw values are used to develop algorithms of pCO 2sw based on sea surface temperature (SST) and position. The algorithms are applied to assimilated SST data and remotely sensed winds on a 1° by 1° grid to estimate the fluxes on weekly timescales in the region. The positive relationship between pCO 2sw and SST is lower than the isochemical trend suggesting counteracting effects from biological processes. The relationship varies systematically with location with a stronger dependence further south. Furthermore, the southern area shows significantly lower pCO 2sw in the fall compared to the spring at the same SST, which is attributed to differences in salinity. The annual algorithms for the entire region show a slight trend between 2002 and 2004 suggesting an increase of pCO 2sw over time. This is in accord with the increasing pCO 2sw due the invasion of anthropogenic CO 2. The annual fluxes of CO 2 yield a net invasion of CO 2 to the ocean that ranges from - 0.04 to - 1.2 mol m - 2 year - 1 over the 3 years. There is a seasonal reversal in the direction of the flux with CO 2 entering into the ocean during the winter and an evasion during the summer. Year-to-year differences in flux are primarily caused by temperature anomalies in the late winter and spring period resulting in changes in invasion during these seasons. An analysis of pCO 2sw before and after hurricane Frances (September 4-6, 2004), and wind records during the storm suggest a large local enhancement of the flux but minimal influence on annual fluxes in the region.

  15. The atmospheric footprint of preindustrial, anthropogenic, and contemporary air-sea fluxes of CO2 estimated from an ocean inversion

    NASA Astrophysics Data System (ADS)

    Mikaloff Fletcher, S. E.; Gruber, N. P.; Sarmiento, J. L.; Jacobson, A. R.

    2006-12-01

    Air-sea exchange is a primary determinant of the spatial pattern of atmospheric carbon dioxide, yet there are substantial gaps in our understanding of the impact of the oceans on these gradients. Recent inverse modeling studies have used ocean interior observations of dissolved inorganic carbon (DIC) and other tracers and Ocean General Circulation Models (OGCMs) to estimate separately the natural air-sea flux that already existed in preindustrial times and the component of the air-sea flux that is due to the anthropogenic perturbation of atmospheric CO2. The sum of these components is the contemporary air-sea flux. Furthermore, the results from the ocean inversion have been combined with an analogous atmospheric inversion using surface observations of atmospheric carbon dioxide concentrations and atmospheric transport models to estimate air- sea and air-land fluxes. This work suggested that there might be an unexpectedly large source of carbon dioxide to the atmosphere from tropical land regions. We use the air-sea fluxes estimated from this ocean inversion together with estimates of the seasonal cycle of these fluxes from ΔpCO2 observations and bulk parameterizations as boundary conditions for the Model for Ozone And Related chemical Tracers (MOZART). The effects of preindustrial, anthropogenic, and contemporary air-sea fluxes on the spatial pattern of atmospheric CO2 are analyzed and the implications for ocean interior transport are discussed. In addition, we use atmospheric observations of 13C/12C isotopic ratios in carbon dioxide to independently test the finding of a large terrestrial source in the tropics, since the terrestrial biosphere discriminates against 13C much more strongly than the oceans.

  16. Reconstruction of super-resolution fields of ocean pCO2 and air-sea fluxes of CO2 from satellite imagery in the Southeastern Atlantic

    NASA Astrophysics Data System (ADS)

    Hernández-Carrasco, I.; Sudre, J.; Garçon, V.; Yahia, H.; Garbe, C.; Paulmier, A.; Dewitte, B.; Illig, S.; Dadou, I.

    2015-01-01

    The knowledge of Green House Gases GHGs fluxes at the air-sea interface at high resolution is crucial to accurately quantify the role of the ocean in the absorption and emission of GHGs. In this paper we present a novel method to reconstruct maps of surface ocean partial pressure of CO2, pCO2, and air-sea CO2 fluxes at super resolution (4 km) using Sea Surface Temperature (SST) and Ocean Colour (OC) data at this resolution, and CarbonTracker CO2 fluxes data at low resolution (110 km). Inference of super-resolution of pCO2, and air-sea CO2 fluxes is performed using novel nonlinear signal processing methodologies that prove efficient in the context of oceanography. The theoretical background comes from the Microcanonical Multifractal Formalism which unlocks the geometrical determination of cascading properties of physical intensive variables. As a consequence, a multiresolution analysis performed on the signal of the so-called singularity exponents allows the correct and near optimal cross-scale inference of GHGs fluxes, as the inference suits the geometric realization of the cascade. We apply such a methodology to the study offshore of the Benguela area. The inferred representation of oceanic partial pressure of CO2 improves and enhances the description provided by CarbonTracker, capturing the small scale variability. We examine different combinations of Ocean Colour and Sea Surface Temperature products in order to increase the number of valid points and the quality of the inferred pCO2 field. The methodology is validated using in-situ measurements by means of statistical errors. We obtain that mean absolute and relative errors in the inferred values of pCO2 with respect to in-situ measurements are smaller than for CarbonTracker.

  17. Air-sea fluxes of CO2 and CH4 from the Penlee Point Atmospheric Observatory on the south-west coast of the UK

    NASA Astrophysics Data System (ADS)

    Yang, Mingxi; Bell, Thomas G.; Hopkins, Frances E.; Kitidis, Vassilis; Cazenave, Pierre W.; Nightingale, Philip D.; Yelland, Margaret J.; Pascal, Robin W.; Prytherch, John; Brooks, Ian M.; Smyth, Timothy J.

    2016-05-01

    We present air-sea fluxes of carbon dioxide (CO2), methane (CH4), momentum, and sensible heat measured by the eddy covariance method from the recently established Penlee Point Atmospheric Observatory (PPAO) on the south-west coast of the United Kingdom. Measurements from the south-westerly direction (open water sector) were made at three different sampling heights (approximately 15, 18, and 27 m above mean sea level, a.m.s.l.), each from a different period during 2014-2015. At sampling heights ≥ 18 m a.m.s.l., measured fluxes of momentum and sensible heat demonstrate reasonable ( ≤ ±20 % in the mean) agreement with transfer rates over the open ocean. This confirms the suitability of PPAO for air-sea exchange measurements in shelf regions. Covariance air-sea CO2 fluxes demonstrate high temporal variability. Air-to-sea transport of CO2 declined from spring to summer in both years, coinciding with the breakdown of the spring phytoplankton bloom. We report, to the best of our knowledge, the first successful eddy covariance measurements of CH4 emissions from a marine environment. Higher sea-to-air CH4 fluxes were observed during rising tides (20 ± 3; 38 ± 3; 29 ± 6 µmole m-2 d-1 at 15, 18, 27 m a.m.s.l.) than during falling tides (14 ± 2; 22 ± 2; 21 ± 5 µmole m-2 d-1), consistent with an elevated CH4 source from an estuarine outflow driven by local tidal circulation. These fluxes are a few times higher than the predicted CH4 emissions over the open ocean and are significantly lower than estimates from other aquatic CH4 hotspots (e.g. polar regions, freshwater). Finally, we found the detection limit of the air-sea CH4 flux by eddy covariance to be 20 µmole m-2 d-1 over hourly timescales (4 µmole m-2 d-1 over 24 h).

  18. Temporal variations in air-sea CO2 exchange near large kelp beds near San Diego, California

    NASA Astrophysics Data System (ADS)

    Ikawa, Hiroki; Oechel, Walter C.

    2015-01-01

    study presents nearly continuous air-sea CO2 flux for 7 years using the eddy covariance method for nearshore water near San Diego, California, as well as identifying environmental processes that appear to control temporal variations in air-sea CO2 flux at different time scales using time series decomposition. Monthly variations in CO2 uptake are shown to be positively influenced by photosynthetically active photon flux density (PPFD) and negatively related to wind speeds. In contrast to the monthly scale, wind speeds often influenced CO2 uptake positively on an hourly scale. Interannual variations in CO2 flux were not correlated with any independent variables, but did reflect surface area of the adjacent kelp bed in the following year. Different environmental influences on CO2 flux at different temporal scales suggest the importance of long-term flux monitoring for accurately identifying important environmental processes for the coastal carbon cycle. Overall, the study area was a strong CO2 sink into the sea (CO2 flux of ca. -260 g C m-2 yr-1). If all coastal areas inhabited by macrophytes had a similar CO2 uptake rate, the net CO2 uptake from these areas alone would roughly equal the net CO2 sink estimated for the entire global coastal ocean to date. A similar-strength CO2 flux, ranging between -0.09 and -0.01 g C m-2 h-1, was also observed over another kelp bed from a pilot study of boat-based eddy covariance measurements.

  19. Effect of Sampling Depth on Air-Sea CO2 Flux Estimates in River-Stratified Arctic Coastal Waters

    NASA Astrophysics Data System (ADS)

    Miller, L. A.; Papakyriakou, T. N.

    2015-12-01

    In summer-time Arctic coastal waters that are strongly influenced by river run-off, extreme stratification severely limits wind mixing, making it difficult to effectively sample the surface 'mixed layer', which can be as shallow as 1 m, from a ship. During two expeditions in southwestern Hudson Bay, off the Nelson, Hayes, and Churchill River estuaries, we confirmed that sampling depth has a strong impact on estimates of 'surface' pCO2 and calculated air-sea CO2 fluxes. We determined pCO2 in samples collected from 5 m, using a typical underway system on the ship's seawater supply; from the 'surface' rosette bottle, which was generally between 1 and 3 m; and using a niskin bottle deployed at 1 m and just below the surface from a small boat away from the ship. Our samples confirmed that the error in pCO2 derived from typical ship-board versus small-boat sampling at a single station could be nearly 90 μatm, leading to errors in the calculated air-sea CO2 flux of more than 0.1 mmol/(m2s). Attempting to extrapolate such fluxes over the 6,000,000 km2 area of the Arctic shelves would generate an error approaching a gigamol CO2/s. Averaging the station data over a cruise still resulted in an error of nearly 50% in the total flux estimate. Our results have implications not only for the design and execution of expedition-based sampling, but also for placement of in-situ sensors. Particularly in polar waters, sensors are usually deployed on moorings, well below the surface, to avoid damage and destruction from drifting ice. However, to obtain accurate information on air-sea fluxes in these areas, it is necessary to deploy sensors on ice-capable buoys that can position the sensors in true 'surface' waters.

  20. Dynamics of air-sea CO2 fluxes in the North-West European Shelf based on Voluntary Observing Ship (VOS) and satellite observations

    NASA Astrophysics Data System (ADS)

    Marrec, P.; Cariou, T.; Macé, E.; Morin, P.; Salt, L. A.; Vernet, M.; Taylor, B.; Paxman, K.; Bozec, Y.

    2015-04-01

    From January 2011 to December 2013, we constructed a comprehensive pCO2 dataset based on voluntary observing ship (VOS) measurements in the Western English Channel (WEC). We subsequently estimated surface pCO2 and air-sea CO2 fluxes in north-west European continental shelf waters using multiple linear regressions (MLRs) from remotely sensed sea surface temperature (SST), chlorophyll a concentration (Chl a), the gas transfer velocity coefficient (K), photosynthetically active radiation (PAR) and modeled mixed layer depth (MLD). We developed specific MLRs for the seasonally stratified northern WEC (nWEC) and the permanently well-mixed southern WEC (sWEC) and calculated surface pCO2 with relative uncertainties of 17 and 16 μatm, respectively. We extrapolated the relationships obtained for the WEC based on the 2011-2013 dataset (1) temporally over a decade and (2) spatially in the adjacent Celtic and Irish Seas (CS and IS), two regions which exhibit hydrographical and biogeochemical characteristics similar to those of WEC waters. We validated these extrapolations with pCO2 data from the SOCAT database and obtained relatively robust results with an average precision of 4 ± 22 μatm in the seasonally stratified nWEC and the southern and northern CS (sCS and nCS), but less promising results in the permanently well-mixed sWEC, IS and Cap Lizard (CL) waters. On an annual scale, seasonally stratified systems acted as a sink of CO2 from the atmosphere of -0.4, -0.9 and -0.4 mol C m-2 year-1 in the nCS, sCS and nWEC, respectively, whereas, permanently well-mixed systems acted as source of CO2 to the atmosphere of 0.2, 0.4 and 0.4 mol C m-2 year-1 in the sWEC, CL and IS, respectively. Air-sea CO2 fluxes showed important inter-annual variability resulting in significant differences in the intensity and/or direction of annual fluxes. We scaled the mean annual fluxes over six provinces for the last decade and obtained the first annual average uptake of -0.95 Tg C year-1 for this

  1. Tuning a physically-based model of the air-sea gas transfer velocity

    NASA Astrophysics Data System (ADS)

    Jeffery, C. D.; Robinson, I. S.; Woolf, D. K.

    Air-sea gas transfer velocities are estimated for one year using a 1-D upper-ocean model (GOTM) and a modified version of the NOAA-COARE transfer velocity parameterization. Tuning parameters are evaluated with the aim of bringing the physically based NOAA-COARE parameterization in line with current estimates, based on simple wind-speed dependent models derived from bomb-radiocarbon inventories and deliberate tracer release experiments. We suggest that A = 1.3 and B = 1.0, for the sub-layer scaling parameter and the bubble mediated exchange, respectively, are consistent with the global average CO 2 transfer velocity k. Using these parameters and a simple 2nd order polynomial approximation, with respect to wind speed, we estimate a global annual average k for CO 2 of 16.4 ± 5.6 cm h -1 when using global mean winds of 6.89 m s -1 from the NCEP/NCAR Reanalysis 1 1954-2000. The tuned model can be used to predict the transfer velocity of any gas, with appropriate treatment of the dependence on molecular properties including the strong solubility dependence of bubble-mediated transfer. For example, an initial estimate of the global average transfer velocity of DMS (a relatively soluble gas) is only 11.9 cm h -1 whilst for less soluble methane the estimate is 18.0 cm h -1.

  2. Carbon isotope evidence for the latitudinal distribution and wind speed dependence of the air-sea gas transfer velocity

    NASA Astrophysics Data System (ADS)

    Krakauer, Nir Y.; Randerson, James T.; Primeau, François W.; Gruber, Nicolas; Menemenlis, Dimitris

    2006-11-01

    The air-sea gas transfer velocity is an important determinant of the exchange of gases, including CO2, between the atmosphere and ocean, but the magnitude of the transfer velocity and what factors control it remains poorly known. Here, we use oceanic and atmospheric observations of 14C and 13C to constrain the global mean gas transfer velocity as well as the exponent of its wind speed dependence, utilizing the distinct signatures left by the air-sea exchange of 14CO2 and 13CO2. While the atmosphere and ocean inventories of 14CO2 and 13CO2 constrain the mean gas transfer velocity, the latitudinal pattern in the atmospheric and oceanic 14C and 13C distributions contain information about the wind speed dependence. We computed the uptake of bomb 14C by the ocean for different transfer velocity patterns using pulse response functions from an ocean general circulation model, and evaluated the match between the predicted bomb 14C concentrations and observationally based estimates for the 1970s-1990s. Using a wind speed climatology based on satellite measurements, we solved either for the best-fit global relationship between gas exchange and mean wind speed or for the mean gas transfer velocity over each of 11 ocean regions. We also compared the predicted consequences of different gas exchange relationships on the rate of change and interhemisphere gradient of 14C in atmospheric CO2 with tree-ring and atmospheric measurements. Our results suggest that globally, the dependence of the air-sea gas transfer velocity on wind speed is close to linear, with an exponent of 0.5 +/- 0.4, and that the global mean gas transfer velocity at a Schmidt number of 660 is 20 +/- 3 cm/hr, similar to the results of previous analyses. We find that the air-sea flux of 13C estimated from atmosphere and ocean observations also suggests a lower than quadratic dependence of gas exchange on wind speed.

  3. Roles of biological and physical processes in driving seasonal air-sea CO2 flux in the Southern Ocean: New insights from CARIOCA pCO2

    NASA Astrophysics Data System (ADS)

    Merlivat, L.; Boutin, J.; Antoine, D.

    2015-07-01

    On a mean annual basis, the Southern Ocean is a sink for atmospheric CO2. However the seasonality of the air-sea CO2 flux in this region is poorly documented. We investigate processes regulating air-sea CO2 flux in a large area of the Southern Ocean (38°S-55°S, 60°W-60°E) that represents nearly one third of the subantarctic zone. A seasonal budget of CO2 partial pressure, pCO2 and of dissolved inorganic carbon, DIC in the mixed layer is assessed by quantifying the impacts of biology, physics and thermodynamical effect on seawater pCO2. A focus is made on the quantification at a monthly scale of the biological consumption as it is the dominant process removing carbon from surface waters. In situ biological carbon production rates are estimated from high frequency estimates of DIC along the trajectories of CARIOCA drifters in the Atlantic and Indian sector of the Southern Ocean during four spring-summer seasons over the 2006-2009 period. Net community production (NCP) integrated over the mixed layer is derived from the daily change of DIC, and mixed layer depth estimated from Argo profiles. Eleven values of NCP are estimated and range from 30 to 130 mmol C m- 2 d- 1. They are used as a constraint for validating satellite net primary production (NPP). A satellite data-based global model is used to compute depth integrated net primary production, NPP, for the same periods along the trajectories of the buoys. Realistic NCP/NPP ratios are obtained under the condition that the SeaWiFS chlorophyll are corrected by a factor of ≈ 2-3, which is an underestimation previously reported for the Southern Ocean. Monthly satellite based NPP are computed over the 38°S-55°S, 60°W-60°E area. pCO2 derived from these NPP combined with an export ratio, and taking into account the impact of physics and thermodynamics is in good agreement with the pCO2 seasonal climatology of Takahashi (2009). On an annual timescale, mean NCP values, 4.4 to 4.9 mol C m- 2 yr- 1 are ≈ 4-5 times

  4. Decadal trends in air-sea CO2 exchange in the Ross Sea (Antarctica)

    NASA Astrophysics Data System (ADS)

    Tagliabue, Alessandro; Arrigo, Kevin R.

    2016-05-01

    Highly productive Antarctic shelf systems, like the Ross Sea, play important roles in regional carbon budgets, but the drivers of local variations are poorly quantified. We assess the variability in the Ross Sea carbon cycle using a regional physical-biogeochemical model. Regionally, total partial pressure of CO2 (pCO2) increases are largely controlled by the biological pump and broadly similar to those in the offshore Southern Ocean. However, this masks substantial local variability within the Ross Sea, where interannual fluctuations in total pCO2 are driven by the biological pump and alkalinity, whereas those for anthropogenic pCO2 are related to physical processes. Overall, the high degree of spatial variability in the Ross Sea carbon cycle causes extremes in aragonite saturation that can be as large as long-term trends. Therefore, Antarctic shelf polynya systems like the Ross Sea will be strongly affected by local processes in addition to larger-scale phenomena.

  5. Evaluation of the swell effect on the air-sea gas transfer in the coastal zone

    NASA Astrophysics Data System (ADS)

    Gutiérrez-Loza, Lucía; Ocampo-Torres, Francisco J.

    2016-04-01

    Air-sea gas transfer processes are one of the most important factors regarding global climate and long-term global climate changes. Despite its importance, there is still a huge uncertainty on how to better parametrize these processes in order to include them on the global climate models. This uncertainty exposes the need to increase our knowledge on gas transfer controlling mechanisms. In the coastal regions, breaking waves become a key factor to take into account when estimating gas fluxes, however, there is still a lack of information and the influence of the ocean surface waves on the air-sea interaction and gas flux behavior must be validated. In this study, as part of the "Sea Surface Roughness as Air-Sea Interaction Control" project, we evaluate the effect of the ocean surface waves on the gas exchange in the coastal zone. Direct estimates of the flux of CO2 (FCO2) and water vapor (FH2O) through eddy covariance, were carried out from May 2014 to April 2015 in a coastal station located at the Northwest of Todos Santos Bay, Baja California, México. For the same period, ocean surface waves are recorded using an Acoustic Doppler Current Profiler (Workhorse Sentinel, Teledyne RD Instruments) with a sampling rate of 2 Hz and located at 10 m depth about 350 m away from the tower. We found the study area to be a weak sink of CO2 under moderate wind and wave conditions with a mean flux of -1.32 μmol/m2s. The correlation between the wind speed and FCO2 was found to be weak, suggesting that other physical processes besides wind may be important factors for the gas exchange modulation at coastal waters. The results of the quantile regression analysis computed between FCO2 and (1) wind speed, (2) significant wave height, (3) wave steepness and (4) water temperature, show that the significant wave height is the most correlated parameter with FCO2; Nevertheless, the behavior of their relation varies along the probability distribution of FCO2, with the linear regression

  6. The potential role of sea spray droplets in facilitating air-sea gas transfer

    NASA Astrophysics Data System (ADS)

    Andreas, E. L.; Vlahos, P.; Monahan, E. C.

    2016-05-01

    For over 30 years, air-sea interaction specialists have been evaluating and parameterizing the role of whitecap bubbles in air-sea gas exchange. To our knowledge, no one, however, has studied the mirror image process of whether sea spray droplets can facilitate air-sea gas exchange. We are therefore using theory, data analysis, and numerical modeling to quantify the role of spray on air-sea gas transfer. In this, our first formal work on this subject, we seek the rate-limiting step in spray-mediated gas transfer by evaluating the three time scales that govern the exchange: τ air , which quantifies the rate of transfer between the atmospheric gas reservoir and the surface of the droplet; τ int , which quantifies the exchange rate across the air-droplet interface; and τ aq , which quantifies gas mixing within the aqueous solution droplet.

  7. The carbon dioxide system on the Mississippi River-dominated continental shelf in the northern Gulf of Mexico: 1. Distribution and air-sea CO2 flux.

    PubMed

    Huang, Wei-Jen; Cai, Wei-Jun; Wang, Yongchen; Lohrenz, Steven E; Murrell, Michael C

    2015-03-01

    River-dominated continental shelf environments are active sites of air-sea CO2 exchange. We conducted 13 cruises in the northern Gulf of Mexico, a region strongly influenced by fresh water and nutrients delivered from the Mississippi and Atchafalaya River system. The sea surface partial pressure of carbon dioxide (pCO2) was measured, and the air-sea CO2 flux was calculated. Results show that CO2 exchange exhibited a distinct seasonality: the study area was a net sink of atmospheric CO2 during spring and early summer, and it was neutral or a weak source of CO2 to the atmosphere during midsummer, fall, and winter. Along the salinity gradient, across the shelf, the sea surface shifted from a source of CO2 in low-salinity zones (0≤S<17) to a strong CO2 sink in the middle-to-high-salinity zones (17≤S<33), and finally was a near-neutral state in the high-salinity areas (33≤S<35) and in the open gulf (S≥35). High pCO2 values were only observed in narrow regions near freshwater sources, and the distribution of undersaturated pCO2 generally reflected the influence of freshwater inputs along the shelf. Systematic analyses of pCO2 variation demonstrated the importance of riverine nitrogen export; that is, riverine nitrogen-enhanced biological removal, along with mixing processes, dominated pCO2 variation along the salinity gradient. In addition, extreme or unusual weather events were observed to alter the alongshore pCO2 distribution and to affect regional air-sea CO2 flux estimates. Overall, the study region acted as a net CO2 sink of 0.96 ± 3.7 mol m(-2) yr(-1) (1.15 ± 4.4 Tg C yr(-1)).

  8. CO2 air-sea fluxes across the Portuguese estuaries Tagus and Sado

    NASA Astrophysics Data System (ADS)

    Oliveira, A. P.; Cabeçadas, G.; Nogueira, M.

    2009-04-01

    Generally, estuaries and proximal shelves under the direct influence of river runoff and large inputs of organic matter are mostly heterotrophic and, therefore, act as a carbon source. In this context the CO2 dynamics in Tagus and Sado estuaries (SW Portugal) was studied under two different climate and hydrological situations. These moderately productive mesotidal coastal-plain lagoon-type estuaries, localised in the center of Portugal and distant 30-40 km apart, present quite different freshwater inflows, surface areas and water residence times. A study performed in 2001 revealed that the magnitude of CO2 fluxes in the two estuarine systems varied seasonally. CO2 emissions during the huge rainfall winter were similar in both estuaries, reaching a mean value of ~50 mmol m-2 d-1, while in spring emissions from Sado were ~6 times higher then Tagus ones, attaining a mean value of 62 mmol m-2 d-1. Nevertheless, in both sampling periods, Sado estuary showed, within the upper estuary (salinity

  9. Synoptic evaluation of carbon cycling in Beaufort Sea during summer: contrasting river inputs, ecosystem metabolism and air-sea CO2 fluxes

    NASA Astrophysics Data System (ADS)

    Forest, A.; Coupel, P.; Else, B.; Nahavandian, S.; Lansard, B.; Raimbault, P.; Papakyriakou, T.; Gratton, Y.; Fortier, L.; Tremblay, J.-É.; Babin, M.

    2013-10-01

    The accelerated decline in Arctic sea ice combined with an ongoing trend toward a more dynamic atmosphere is modifying carbon cycling in the Arctic Ocean. A critical issue is to understand how net community production (NCP; the balance between gross primary production and community respiration) responds to changes and modulates air-sea CO2 fluxes. Using data collected as part of the ArcticNet-Malina 2009 expedition in southeastern Beaufort Sea (Arctic Ocean), we synthesize information on sea ice, wind, river, water column properties, metabolism of the planktonic food web, organic carbon fluxes and pools, as well as air-sea CO2 exchange, with the aim of identifying indices of ecosystem response to environmental changes. Data were analyzed to develop a non-steady-state carbon budget and an assessment of NCP against air-sea CO2 fluxes. The mean atmospheric forcing was a mild upwelling-favorable wind (~5 km h-1) blowing from the N-E and a decaying ice cover (<80% concentration) was observed beyond the shelf, the latter being fully exposed to the atmosphere. We detected some areas where the surface mixed layer was net autotrophic owing to high rates of primary production (PP), but the ecosystem was overall net heterotrophic. The region acted nonetheless as a sink for atmospheric CO2 with a mean uptake rate of -2.0 ± 3.3 mmol C m-2d-1. We attribute this discrepancy to: (1) elevated PP rates (>600 mg C m-2d-1) over the shelf prior to our survey, (2) freshwater dilution by river runoff and ice melt, and (3) the presence of cold surface waters offshore. Only the Mackenzie River delta and localized shelf areas directly affected by upwelling were identified as substantial sources of CO2 to the atmosphere (>10mmol C m-2d-1). Although generally <100 mg C m-2d-1, daily PP rates cumulated to a total PP of ~437.6 × 103 t C, which was roughly twice higher than the organic carbon delivery by river inputs (~241.2 × 103 t C). Subsurface PP represented 37.4% of total PP for the

  10. Biofilm-like properties of the sea surface and predicted effects on air-sea CO2 exchange

    NASA Astrophysics Data System (ADS)

    Wurl, Oliver; Stolle, Christian; Van Thuoc, Chu; The Thu, Pham; Mari, Xavier

    2016-05-01

    Because the sea surface controls various interactions between the ocean and the atmosphere, it has a profound function for marine biogeochemistry and climate regulation. The sea surface is the gateway for the exchange of climate-relevant gases, heat and particles. Thus, in order to determine how the ocean and the atmosphere interact and respond to environmental changes on a global scale, the characterization and understanding of the sea surface are essential. The uppermost part of the water column is defined as the sea-surface microlayer and experiences strong spatial and temporal dynamics, mainly due to meteorological forcing. Wave-damped areas at the sea surface are caused by the accumulation of surface-active organic material and are defined as slicks. Natural slicks are observed frequently but their biogeochemical properties are poorly understood. In the present study, we found up to 40 times more transparent exopolymer particles (TEP), the foundation of any biofilm, in slicks compared to the underlying bulk water at multiple stations in the North Pacific, South China Sea, and Baltic Sea. We found a significant lower enrichment of TEP (up to 6) in non-slick sea surfaces compared to its underlying bulk water. Moreover, slicks were characterized by a large microbial biomass, another shared feature with conventional biofilms on solid surfaces. Compared to non-slick samples (avg. pairwise similarity of 70%), the community composition of bacteria in slicks was increasingly (avg. pairwise similarity of 45%) different from bulk water communities, indicating that the TEP-matrix creates specific environments for its inhabitants. We, therefore, conclude that slicks can feature biofilm-like properties with the excessive accumulation of particles and microbes. We also assessed the potential distribution and frequency of slick-formation in coastal and oceanic regions, and their effect on air-sea CO2 exchange based on literature data. We estimate that slicks can reduce CO2

  11. Mapping of the air-sea CO2 flux in the Arctic Ocean and its adjacent seas: Basin-wide distribution and seasonal to interannual variability

    NASA Astrophysics Data System (ADS)

    Yasunaka, Sayaka; Murata, Akihiko; Watanabe, Eiji; Chierici, Melissa; Fransson, Agneta; van Heuven, Steven; Hoppema, Mario; Ishii, Masao; Johannessen, Truls; Kosugi, Naohiro; Lauvset, Siv K.; Mathis, Jeremy T.; Nishino, Shigeto; Omar, Abdirahman M.; Olsen, Are; Sasano, Daisuke; Takahashi, Taro; Wanninkhof, Rik

    2016-09-01

    We produced 204 monthly maps of the air-sea CO2 flux in the Arctic north of 60°N, including the Arctic Ocean and its adjacent seas, from January 1997 to December 2013 by using a self-organizing map technique. The partial pressure of CO2 (pCO2) in surface water data were obtained by shipboard underway measurements or calculated from alkalinity and total inorganic carbon of surface water samples. Subsequently, we investigated the basin-wide distribution and seasonal to interannual variability of the CO2 fluxes. The 17-year annual mean CO2 flux shows that all areas of the Arctic Ocean and its adjacent seas were net CO2 sinks. The estimated annual CO2 uptake by the Arctic Ocean was 180 TgC yr-1. The CO2 influx was strongest in winter in the Greenland/Norwegian Seas (>15 mmol m-2 day-1) and the Barents Sea (>12 mmol m-2 day-1) because of strong winds, and strongest in summer in the Chukchi Sea (∼10 mmol m-2 day-1) because of the sea-ice retreat. In recent years, the CO2 uptake has increased in the Greenland/Norwegian Sea and decreased in the southern Barents Sea, owing to increased and decreased air-sea pCO2 differences, respectively.

  12. Transfer Processes at the Air--Sea Interface

    NASA Astrophysics Data System (ADS)

    Guymer, T. H.; Businger, J. A.; Katsaros, K. B.; Shaw, W. J.; Taylor, P. K.; Large, W. G.; Payne, R. E.

    1983-02-01

    Near-surface data from ships, buoys, aircraft and a microwave remote-sensing satellite have been used to estimate the fluxes of momentum, heat and water vapour at the sea surface over a 200 km × 200 km area during the Joint Air--Sea Interaction Experiment of 1978. In particular, daily means of the surface heat balance and the wind stress are presented. Generally, the sensible heat flux was found to be less than 25% of the latent heat flux. Over periods of a day the total upward heat flux was about a third of the net radiation, implying that a significant proportion of the available energy went into heating the ocean. The Ekman pumping accounted for most of the divergence in the atmospheric boundary layer but only 10% at most of that in the upper ocean. Some case studies of the horizontal variation of the fluxes in relation to larger scales are also discussed and it is suggested that the fluxes are modulated by mesoscale patterns in sea-surface temperature. Surface turbulent fluxes and SST have been examined on scales from several kilometres to 200 km and for days to weeks by using a combination of ships, buoys, aircraft and microwave remote sensing. The net radiative flux had been obtained at the corners of the 200 km meteorological triangle either by direct measurements of the shortwave and longwave components or by parametrization techniques. This has enabled the surface heat budget to be examined on a daily basis. About 70% of the net flux (typically 100 W m-2 in phase 1 and 70 W m-2 in phase 2) is available for heating the ocean and, of the remainder, over 75% goes into the atmosphere as latent heat. In these near-neutral conditions the mean surface wind speed across the triangle was 77% of the geostrophic wind speed and the cross-isobar flow angle was 11 degrees (down-gradient). Significant variations in the thermodynamic fluxes across the area were found, associated partly with the SST distribution and also with the fact that the coldest and driest air was

  13. Assessing the sensitivity of modeled air-sea CO2 exchange to the remineralization depth of particulate organic and inorganic carbon

    NASA Astrophysics Data System (ADS)

    Schneider, Birgit; Bopp, Laurent; Gehlen, Marion

    2008-09-01

    To assess the sensitivity of surface ocean pCO2 and air-sea CO2 fluxes to changes in the remineralization depth of particulate organic and inorganic carbon (POC, PIC), a biogeochemical ocean circulation model (PISCES) was run with different parameterizations for vertical particle fluxes. On the basis of fluxes of POC and PIC, productivity, export, and the distributions of nitrogen (NO3), dissolved inorganic carbon (DIC), and alkalinity, a number of indices defined to estimate the efficiency of carbon transport away from the atmosphere are applied. With differing success for the respective indices the results show that the more efficient the vertical transport of organic carbon toward depth, the lower the surface ocean pCO2, the higher the air-sea CO2 flux, and the stronger the increase in the oceanic inventory of DIC. Along with POC flux it is important to consider variations in PIC flux, as the net effect of particle flux reorganizations on surface ocean pCO2 is a combination of changes in DIC and alkalinity. The results demonstrate that changes in the mechanistic formulation of vertical particle fluxes have direct and indirect effects on surface ocean pCO2 and may thus interact with the atmospheric CO2 reservoir.

  14. Spatio-temporal dynamics of biogeochemical processes and air-sea CO2 fluxes in the Western English Channel based on two years of FerryBox deployment

    NASA Astrophysics Data System (ADS)

    Marrec, P.; Cariou, T.; Latimier, M.; Macé, E.; Morin, P.; Vernet, M.; Bozec, Y.

    2014-12-01

    From January 2011 to January 2013, a FerryBox system was installed on a Voluntary Observing Ship (VOS), which crossed the Western English Channel (WEC) between Roscoff (France) and Plymouth (UK) up to 3 times a day. The FerryBox continuously measured sea surface temperature (SST), sea surface salinity (SSS), dissolved oxygen (DO), fluorescence and partial pressure of CO2 (from April 2012) along the ferry track. Sensors were calibrated based on 714 bimonthly surface samplings with precisions of 0.016 for SSS, 3.3 μM for DO, 0.40 μg L- 1 for Chlorophyll-a (Chl-a) (based on fluorescence measurements) and 5.2 μatm for pCO2. Over the 2 years of deployment (900 crossings), we reported 9% of data lost due to technical issues and quality checked data was obtained to allow investigation of the dynamics of biogeochemical processes related to air-sea CO2 fluxes in the WEC. Based on this unprecedented high-frequency dataset, the physical structure of the WEC was assessed using SST anomalies and the presence of a thermal front was observed around the latitude 49.5°N, which divided the WEC in two main provinces: the seasonally stratified northern WEC (nWEC) and the all-year well-mixed southern WEC (sWEC). These hydrographical properties strongly influenced the spatial and inter-annual distributions of phytoplankton blooms, which were mainly limited by nutrients and light availability in the nWEC and the sWEC, respectively. Air-sea CO2 fluxes were also highly related to hydrographical properties of the WEC between late April and early September 2012, with the sWEC a weak source of CO2 to the atmosphere of 0.9 mmol m- 2 d- 1, whereas the nWEC acted as a sink for atmospheric CO2 of 6.9 mmol m- 2 d- 1. The study of short time-scale dynamics of air-sea CO2 fluxes revealed that an intense and short (less than 10 days) summer bloom in the nWEC contributed to 29% of the CO2 sink during the productive period, highlighting the necessity for high frequency observations in coastal

  15. Response of biological production and air-sea CO2 fluxes to upwelling intensification in the California and Canary Current Systems

    NASA Astrophysics Data System (ADS)

    Lachkar, Zouhair; Gruber, Nicolas

    2013-01-01

    Upwelling-favorable winds have increased in most Eastern Boundary Upwelling Systems (EBUS) in the last decades, and it is likely that they increase further in response to global climate change. Here, we explore the response of biological production and air-sea CO2 fluxes to upwelling intensification in two of the four major EBUS, namely the California Current System (California CS) and Canary Current System (Canary CS). To this end, we use eddy-resolving regional ocean models on the basis of the Regional Oceanic Modeling System (ROMS) to which we have coupled a NPZD-type ecosystem model and a biogeochemistry module describing the carbon cycle and subject these model configurations to an idealized increase in the wind stress. We find that a doubling of the wind-stress doubles net primary production (NPP) in the southern California CS and central and northern Canary CS, while it leads to an increase of less than 50% in the central and northern California CS as well as in the southern Canary CS. This differential response is a result of i) different nutrient limitation states with higher sensitivity to upwelling intensification in regions where nutrient limitation is stronger and ii) more efficient nutrient assimilation by biology in the Canary CS relative to the California CS because of a faster nutrient-replete growth rate and longer nearshore water residence times. In the regions where production increases commensurably with upwelling intensification, the enhanced net biological uptake of CO2 compensates the increase in upwelling driven CO2 outgassing, resulting in only a small change in the biological pump efficiency and hence in a small sensitivity of air-sea CO2 fluxes to upwelling intensification. In contrast, in the central California CS as well as in the southern Canary CS around Cape Blanc, the reduced biological efficiency enhances the CO2 outgassing and leads to a substantial sensitivity of the air-sea CO2 fluxes to upwelling intensification.

  16. Air-sea CO2 exchange process in the southern Yellow Sea in April of 2011, and June, July, October of 2012

    NASA Astrophysics Data System (ADS)

    Qu, Baoxiao; Song, Jinming; Yuan, Huamao; Li, Xuegang; Li, Ning

    2014-06-01

    The partial pressure of CO2 (pCO2) and air-sea CO2 exchange flux (FCO2) in the southern Yellow Sea (SYS, 120-125°E, 31.5-37°N) were investigated basing on the field surveys conducted in April of 2011, and June, July, October of 2012. With significant spatial variations, surface pCO2 ranged from 243 to 574 μatm, 206 to 620 μatm, 102 to 655 μatm and 328 to 557 μatm in April, June, July and October, respectively. Nearshore area of Shandong Peninsula and Jiangsu Shallow (depth<50 m) were pCO2-supersaturated (pCO2=400-600 μatm), as the result of intensive water mixing which brought the bottom CO2-rich water to the surface layer. Conversely, offshore area of SYS center (depth>50 m) was pCO2-undersaturated (pCO2<390 μatm) in April, June and October, but supersaturated in July. Phytoplankton production sustained by abundant nutrient and suitable hydrodynamic conditions was of great importance for this undersaturated pCO2. Moreover, extreme low pCO2 (pCO2<300 μatm) was observed in the Changjiang plume (32.5-33.5°N, 123-125°E) in July, which was also related with the biological uptake of CO2. Average air-sea CO2 exchange flux of the SYS in April, June, July and October was -3.16±0.40 mmol m-2 d-1, -4.56±0.34 mmol m-2 d-1, -0.36±0.51 mmol m-2 d-1, and 6.67±0.57 mmol m-2 d-1, respectively. As a whole, the SYS behaved as a weak CO2 sink during April to October, with an average flux for about -0.35 mmol m-2 d-1. As for the controlling factors for pCO2 variation, temperature played the dominant role in October, whereas the non-temperature factors, such as vertical mixing, Changjiang plume and biological activity, were considered as the primary controlling factors in June and July. Spatially, the control of temperature on pCO2 was predominant in the offshore SYS; the non-temperature factors were predominant in the shallow nearshore area, especially in coast of Shandong Peninsula and the Jiangsu Shallow.

  17. Natural Air-Sea Flux of CO2 in Simulations of the NASA-GISS Climate Model: Sensitivity to the Physical Ocean Model Formulation

    NASA Technical Reports Server (NTRS)

    Romanou, A.; Gregg, Watson W.; Romanski, J.; Kelley, M.; Bleck, R.; Healy, R.; Nazarenko, L.; Russell, G.; Schmidt, G. A.; Sun, S.; Tausnev, N.

    2013-01-01

    Results from twin control simulations of the preindustrial CO2 gas exchange (natural flux of CO2) between the ocean and the atmosphere are presented here using the NASA-GISS climate model, in which the same atmospheric component (modelE2) is coupled to two different ocean models, the Russell ocean model and HYCOM. Both incarnations of the GISS climate model are also coupled to the same ocean biogeochemistry module (NOBM) which estimates prognostic distributions for biotic and abiotic fields that influence the air-sea flux of CO2. Model intercomparison is carried out at equilibrium conditions and model differences are contrasted with biases from present day climatologies. Although the models agree on the spatial patterns of the air-sea flux of CO2, they disagree on the strength of the North Atlantic and Southern Ocean sinks mainly because of kinematic (winds) and chemistry (pCO2) differences rather than thermodynamic (SST) ones. Biology/chemistry dissimilarities in the models stem from the different parameterizations of advective and diffusive processes, such as overturning, mixing and horizontal tracer advection and to a lesser degree from parameterizations of biogeochemical processes such as gravitational settling and sinking. The global meridional overturning circulation illustrates much of the different behavior of the biological pump in the two models, together with differences in mixed layer depth which are responsible for different SST, DIC and nutrient distributions in the two models and consequently different atmospheric feedbacks (in the wind, net heat and freshwater fluxes into the ocean).

  18. Synoptic evaluation of carbon cycling in the Beaufort Sea during summer: contrasting river inputs, ecosystem metabolism and air-sea CO2 fluxes

    NASA Astrophysics Data System (ADS)

    Forest, A.; Coupel, P.; Else, B.; Nahavandian, S.; Lansard, B.; Raimbault, P.; Papakyriakou, T.; Gratton, Y.; Fortier, L.; Tremblay, J.-É.; Babin, M.

    2014-05-01

    The accelerated decline in Arctic sea ice and an ongoing trend toward more energetic atmospheric and oceanic forcings are modifying carbon cycling in the Arctic Ocean. A critical issue is to understand how net community production (NCP; the balance between gross primary production and community respiration) responds to changes and modulates air-sea CO2 fluxes. Using data collected as part of the ArcticNet-Malina 2009 expedition in the southeastern Beaufort Sea (Arctic Ocean), we synthesize information on sea ice, wind, river, water column properties, metabolism of the planktonic food web, organic carbon fluxes and pools, as well as air-sea CO2 exchange, with the aim of documenting the ecosystem response to environmental changes. Data were analyzed to develop a non-steady-state carbon budget and an assessment of NCP against air-sea CO2 fluxes. During the field campaign, the mean wind field was a mild upwelling-favorable wind (~ 5 km h-1) from the NE. A decaying ice cover (< 80% concentration) was observed beyond the shelf, the latter being fully exposed to the atmosphere. We detected some areas where the surface mixed layer was net autotrophic owing to high rates of primary production (PP), but the ecosystem was overall net heterotrophic. The region acted nonetheless as a sink for atmospheric CO2, with an uptake rate of -2.0 ± 3.3 mmol C m-2 d-1 (mean ± standard deviation associated with spatial variability). We attribute this discrepancy to (1) elevated PP rates (> 600 mg C m-2 d-1) over the shelf prior to our survey, (2) freshwater dilution by river runoff and ice melt, and (3) the presence of cold surface waters offshore. Only the Mackenzie River delta and localized shelf areas directly affected by upwelling were identified as substantial sources of CO2 to the atmosphere (> 10 mmol C m-2 d-1). Daily PP rates were generally < 100 mg C m-2 d-1 and cumulated to a total PP of ~ 437.6 × 103 t C for the region over a 35-day period. This amount was about twice the

  19. Sensitivity of air-sea CO2-exchange and calcite saturation depth to the remineralization depth of marine particulate organic and inorganic carbon

    NASA Astrophysics Data System (ADS)

    Schneider, B.; Bopp, L.; Gehlen, M.

    2009-04-01

    The present study addresses the question of what would happen to air-sea CO2 exchange and the depth of the calcite saturation horizon (CSH) if the remineralization depth of particulate organic and inorganic carbon (POC, PIC) was changing. Therefore, a biogeochemical ocean circulation model (PISCES) was run with four different parameterizations for vertical particle fluxes, starting from the same initial conditions. Particle fluxes undergo strong changes induced by a combination of the respective mechanistic formulation of the vertical particle flux and the resulting ecosystem response. Reorganizations in dissolved properties are caused by (i) changed fluxes of POC and PIC; (ii) advection; (iii) air-sea CO2 exchange (DIC). The results show that the more (less) efficient the vertical transport of POC (PIC) from the surface toward depth, the lower the surface ocean pCO2, the higher the air-sea CO2 flux, and the stronger the increase in the oceanic inventory of DIC, and vice versa. Consequently, in one experiment the ocean is turning into a CO2 source to the atmosphere, in two cases it becomes a weak sink and in one simulation it turns into a strong sink. Surprisingly, results for changes in the CSH are more similar among the simulations at larger scale with a general deepening in the North Pacific and a shoaling elsewhere. In most areas the readjustment of the CSH is controlled by DIC and alkalinity acting both towards the simulated CSH shifts, however, in some cases DIC (alkalinity) is overcompensating for an effect that would occur due to changes in alkalinity (DIC), alone. In detail, the differences found between the experiments can be well explained by the respective particle flux responses. The current study shows that reorganizations in the vertical flux of particulate matter in the ocean may have immediate and longer-term effects on the marine carbon cycle which could potentially feedback on the climate system.

  20. Validation study of air-sea gas transfer modeling

    SciTech Connect

    Asher, W.E.; Farley, P.J.; Leifer, I.S.

    1995-07-01

    Laboratory results have demonstrated the importance of bubble plumes to air-water gas transfer (Asher et al., 1994). Bubble plumes enhance gas transfer by disrupting surface films, by directly transporting a gas, and by the creation of turbulence. Models of bubble gas transfer have been developed by different authors (Atkinson, 1973; Memery and Merlivat, 1985; Woolf and Thorpe, 1991) to determine the magnitude of gas transfer due to bubbles. Laboratory measurements of both the gas transfer rate k{sub L}, and the bubble distribution {phi} in a whitecap simulation tank (WST) have allowed these models to be validated and deficiencies in the theoretical assumptions to be explored. In the WST, each bucket tip simulates a wave breaking event. Important tests of these models include whether they can explain the experimentally determined solubility and Schmidt number dependency of k{sub L}, predict the time varying bubble concentrations, predict the evasion-invasion asymmetry, and predict the fraction of k{sub L} due to bubble plumes. Four different models were tested, a steady state model (Atkinson, 1973), a non-turbulence model with constant bubble radius (Memery and Merlivat, 1985), a turbulence model with constant bubble radius (Wolf and Thorpe, 1991), and a turbulence model with varying bubble radius. All models simulated multiple bubble tip cycles. The two turbulence models were run for sufficient tip cycles to generate statistically significant number of eddies ({number_sign}{gt}50) for bubbles affected by turbulence (V{sub B}{le}V{sub T}), found to be at least four tip cycles. The models allowed up to nine gases simultaneously and were run under different conditions of trace and major gas concentrations and partial pressures.

  1. Design and construction of Information Systems of Ocean Satellite Monitoring for Air-sea CO2 Flux (IssCO2)

    NASA Astrophysics Data System (ADS)

    Zhu, Qiankun; Fang, Lei; Bai, Yan; He, Xianqiang; Sun, Xiaoxiao; Chen, Jianyu

    2013-10-01

    Climate change has become one of the hotspots of global attention in recent progress of globalization and industrialization. The mainstream opinion presented by Intergovernmental Panel on Climate Change (IPCC) regards that the global warming was caused mainly by greenhouse gases generated by human activities, such as anthropogenic CO2, which also resulting in the high-frequent happening of abnormal climate events. Satellite remote sensing is an efficient and economic method for CO2 flux observation. In this paper, we describe an Information System of Ocean Satellite Monitoring for Ari-sea CO2 Flux (IssCO2) which developed by the Second Institute of Oceanography, China. The IssCO2can achieve the whole procedure automatically from the satellite remote data receiving to products distribution, including the data acquirement and satellite image process, products generation, etc. The IssCO2 can process various types of in situ data, satellite data and model data, and validate the final satellite-derived CO2 flux products by in situ data; it can provide a real-time browsing and download of remote sensing products on the web based on the Geo-information System (GIS) technologies. The IssCO2 can meet the concurrent queries of different levels of users, and the query results can be visual displayed and analyzed on the client.

  2. Multi-Satellite Characterization of Interannual Variation in Primary Production and Air-Sea CO2 Flux in the Ross Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Arrigo, K. R.

    2005-12-01

    The Ross Sea is the most productive sector of the Southern Ocean, the largest of the three iron limited HNLC regions. This productivity supports a rich upper trophic level community, including large numbers of penguins, seals, and whales. It also represents a large sink for atmospheric CO2. Since the advent of ocean color remote sensing using satellites such as CZCS, SeaWiFS, and MODIS, it has become increasingly clear that productivity in the Ross Sea is also characterized by a great deal of interannual variability. Passive microwave data from the Special Sensor Microwave/Imager show that distributions of sea ice within the Ross Sea vary markedly from year to year, with some years experiencing nearly ice-free springtime conditions while others remain nearly ice covered. This extreme variability in sea ice cover is due to changes in climate state as well as some unusual events specific to the Ross Sea, such as the calving of two enormous icebergs, one in 2000 and the other in 2002. Variation in ice cover during austral spring and summer impacts the growth of the phytoplankton community, whose cumulative rate of annual primary production ranges widely, from <10 Tg C in 2002-03 to almost 40 Tg C in 1999-00. When these satellite data are used in conjunction with a three-dimensional ocean ecosystem model of the Ross Sea, the calculated air-sea fluxes of CO2 are even more variable, varying over 50-fold between 1997 and 2004. Not surprisingly, the lowest atmospheric flux of CO2 into the surface waters of the Ross Sea (0.10 Tg C) is associated with the year having the lowest primary production and highest sea ice cover. The extreme sensitivity of rates of primary production and particularly air-sea CO2 fluxes to changes in sea ice distribution in the Southern Ocean suggest that this region may undergo dramatic changes if global temperatures continue to rise, as they have in the vicinity of the Antarctic Peninsula.

  3. Simultaneous measurements of air-sea gas transfer velocity and near surface turbulence at low to moderate winds (Invited)

    NASA Astrophysics Data System (ADS)

    Wang, B.; Liao, Q.; Fillingham, J. H.; Bootsma, H. A.

    2013-12-01

    Parameterization of air-sea gas transfer velocity was routinely made with wind speed. Near surface turbulent dissipation rate has been shown to have better correlation with the gas transfer velocity in a variety of aquatic environments (i.e., the small eddy model) while wind speed is low to moderate. Wind speed model may underestimate gas transfer velocity at low to moderate winds when the near surface turbulence is produced by other environmental forcing. We performed a series of field experiments to measure the CO2 transfer velocity, and the statistics of turbulence immediately below the air-water interface using a novel floating PIV and chamber system. The small eddy model was evaluated and the model coefficient was found to be a non-constant, and it varies with the local turbulent level (figure 1). Measure results also suggested an appropriate scaling of the vertical dissipation profile immediately below the interface under non-breaking conditions, which can be parameterized by the wind shear, wave height and wave age (figure 2). Figure 1. Relation between the coefficient of the small eddy model and dissipation rate. The data also include Chu & Jirka (2003) and Vachon et al. (2010). The solid regression line: α = 0.188log(ɛ)+1.158 Figure 2. Non-dimensional dissipation profiles. Symbols: measured data with the floating PIV. Solid line: regression of measured data with a -0.79 decaying rate. Dash line with -2 slope: Terray et al. (1996) relation. Dash line with two layer structure: Siddiqui & Loewen (2007) relation.

  4. Air-Sea CO2 fluxes and NEP changes in a Baja California Coastal Lagoon during the anomalous North Pacific warm condition in 2014

    NASA Astrophysics Data System (ADS)

    Ávila López, M. D. C.; Martin Hernandez-Ayon, J. M.; Camacho-Ibar, V.; Sandoval Gil, J.; Mejía-Trejo, A.; Félix-Bermudez, A.; Pacheco-Ruiz, I.

    2015-12-01

    The present study examines the temporal variability of seawater carbonate chemistry and air-sea CO2 fluxes (FCO2) in a Baja California Mediterranean-climate coastal lagoon. This study was carried out from Nov-2013 to Nov-2014, a period in which anomalous warm conditions were present in the North Pacific Ocean influenced the local oceanography in the adjacent coastal waters off Baja California. These ocean conditions resulted on a negative anomaly of upwelling index, which led to summer-like season (weak upwelling condition) that could be observed in the response of carbon dynamics and metabolic status in San Quintín Bay. Minor changes in dissolved inorganic carbon (DIC) concentration during spring months (~100 µmol kg-1) where observed and were associated to biological processes within the lagoon. High DIC (~2200 µmol kg-1), pCO2 (~800 μatm), and minimum pH (~7.8) values were observed in summer, reflecting the predominance of respiration processes apparently mostly linked to the remineralization of sedimentary organic matter supplied from macroalgal blooms. San Quintín Bay acted as a weak source of CO2 to the atmosphere during the study period, with maximum value observed in July (~10 mmol C m-2 d-1). Temporal biomass production of macroalgae contributed to about 50% of total FCO2 estimated in spring-summer seasons, that was a potencial internal source of organic matter to fuel respiration processes in San Quintín Bay. Eelgrass metabolism contributes in a lower degree in total FCO2. During the anomalous ocean conditions in 2014, the lagoon switched seasonally between net heterotrophy and net autotrophy during the study period, where photosynthesis and respiration processes in the lagoon were closer to a balance. Whole-system metabolism and FCO2 clearly indicated the strong dependence of San Quintín Bay on upwelling conditions and benthic metabolism activity, which was mainly controlled by dominant primary producer communities.

  5. Mechanisms driving the seasonality of air-sea CO2 flux in the ice-free zone of the Southern Ocean and how these might evolve: A 1D vertical biogeochemical model approach.

    NASA Astrophysics Data System (ADS)

    Lancelot, C.; Pasquer, B.; Metzl, N.; Goosse, H.

    2015-12-01

    The biogeochemical SWAMCO-3 model is used to understand mechanisms governing the seasonality of air-sea CO2 exchanges in the ice-free Southern Ocean. The model explicitly details the dynamics of three Phytoplankton Functional Types (PFTs) of importance for C, N, P, Si, Fe cycling and air-sea CO2 exchange in this area. These are the diatoms, the pico-nanophytoplankton and the coccolithophores whose growth regulation by light, temperature and nutrients has been obtained from phenomenological observations available for these PFTs. The performance of the SWAMCO-3 model coupled to a vertical one-dimensional physical model is assessed at the location of the time-series station KERFIX (around 51°S-68°E). The model was able to reproduce a mean seasonal cycle based on years where a maximum of chemical and biological observations are available. Ocean fCO2 in equilibrium with the atmosphere are simulated both in winter associated with surface layer replenishment in DIC due to deep vertical mixing and in late summer as a consequence of the warming effect on the carbonate system. A clear under-saturation is simulated in summer driven by primary production. Model scenarios cancelling biological activity or only coccolithophores allowed, by comparison with the standard simulation, untangling the respective role of physical and biological processes in driving the sign and magnitude of air-sea CO2 exchanges. First, we show that coccolithophores are repressing the ocean C uptake, but only marginally (5%). Second, the model highlights the role of diatoms on the presence of a CO2 sink in summer. Altogether, this results in a weak annual air-sea CO2 flux (-0.9 mol m-2 y-1 or -0.1 Pg C y-1 for the ice-free zone south of 50°S), whose variability seems more related to the thermodynamical processes. We then speculate how global warming might influence the latter mechanisms and alter air-sea CO2 exchanges in this region.

  6. Measuring Nitrous Oxide Mass Transfer into Non-Aqueous CO2BOL CO2 Capture Solvents

    SciTech Connect

    Whyatt, Greg A.; Freeman, Charles J.; Zwoster, Andy; Heldebrant, David J.

    2016-03-28

    This paper investigates CO2 absorption behavior in CO2BOL solvents by decoupling the physical and chemical effects using N2O as a non-reactive mimic. Absorption measurements were performed using a wetted-wall contactor. Testing was performed using a “first generation” CO2 binding organic liquid (CO2BOL), comprised of an independent base and alcohol. Measurements were made with N2O at a lean (0.06 mol CO2/mol BOL) and rich (0.26 mol CO2/mol BOL) loading, each at three temperatures (35, 45 and 55 °C). Liquid-film mass transfer coefficients (kg') were calculated by subtracting the gas film resistance – determined from a correlation from literature – from the overall mass transfer measurement. The resulting kg' values for N2O in CO2BOLs were found to be higher than that of 5 M aqueous MEA under comparable conditions, which is supported by published measurements of Henry’s coefficients for N2O in various solvents. These results suggest that the physical solubility contribution for CO2 absorption in CO2BOLs is greater than that of aqueous amines, an effect that may pertain to other non-aqueous solvents.

  7. The role of breaking wavelets in air-sea gas transfer

    NASA Astrophysics Data System (ADS)

    Csanady, G. T.

    1990-01-01

    Molecular diffusion sustains the flux of soluble gases on the water side of the air-sea interface. The "handover" of this flux to more efficient eddy mixing begins with the smallest eddies, of size l;, which interact with the surface diffusion boundary layer (DBL), of thickness δ. Owing to the discrepancy of the scales, δ ≪ l, the flow field on the δ scale consists of horizontal motions of a velocity constant with depth and varying horizontally on the l scale. The vertical velocity is proportional to the divergence of the horizontal flow and increases linearly with depth. An exact solution of the advection-diffusion equation for the simple model of divergent stagnation point flow shows the mass transfer coefficient (velocity) k to be proportional to (aD1/2) and DBL thickness δ to be proportional to (D/a1/2), where a is divergence, D diffusivity. Over a solid wall a similar model of Hiemenz flow yields a more complex relationship, also involving viscosity. These models reveal the mechanism by which the DBL is kept thin. The most intense surface divergences on a wind-blown sea surface are associated with rollers on breaking wavelets. Vorticity and divergence in the rollers are both proportional to u*2/v;, where u* is friction velocity and v is viscosity. The mass transfer coefficient resulting from divergences of this magnitude is then given by k = const u* Sc-1/2, where Sc is Schmidt number. Exact solutions of the advection-diffusion equation for model rollers reveal the details of the handover process. A thin DBL is maintained over divergences by the upward velocity. At convergences, narrow downward plumes convey DBL fluid into the turbulent interior. Flux lines (analogous to streamlines) are horizontal over divergences and dive down under convergences. Application to the sea surface requires a parameter quantifying the surface density of divergences. Laboratory data imply that a substantial fraction of the surface is covered by the divergences at higher wind

  8. Sensitivity analysis of an ocean carbon cycle model in the North Atlantic: an investigation of parameters affecting the air-sea CO2 flux, primary production and export of detritus

    NASA Astrophysics Data System (ADS)

    Scott, V.; Kettle, H.; Merchant, C. J.

    2011-06-01

    The sensitivity of the biological parameters in a nutrient-phytoplankton-zooplankton-detritus (NPZD) model in the calculation of the air-sea CO2 flux, primary production and detrital export is analysed. We explore the effect on these outputs of variation in the values of the twenty parameters that control ocean ecosystem growth in a 1-D formulation of the UK Met Office HadOCC NPZD model used in GCMs. We use and compare the results from one-at-a-time and all-at-a-time perturbations performed at three sites in the EuroSITES European Ocean Observatory Network: the Central Irminger Sea (60° N 40° W), the Porcupine Abyssal Plain (49° N 16° W) and the European Station for Time series in the Ocean Canary Islands (29° N 15° W). Reasonable changes to the values of key parameters are shown to have a large effect on the calculation of the air-sea CO2 flux, primary production, and export of biological detritus to the deep ocean. Changes in the values of key parameters have a greater effect in more productive regions than in less productive areas. The most sensitive parameters are generally found to be those controlling well-established ocean ecosystem parameterisations widely used in many NPZD-type models. The air-sea CO2 flux is most influenced by variation in the parameters that control phytoplankton growth, detrital sinking and carbonate production by phytoplankton (the rain ratio). Primary production is most sensitive to the parameters that define the shape of the photosynthesis-irradiance curve. Export production is most sensitive to the parameters that control the rate of detrital sinking and the remineralisation of detritus.

  9. Sensitivity analysis of an Ocean Carbon Cycle Model in the North Atlantic: an investigation of parameters affecting the air-sea CO2 flux, primary production and export of detritus

    NASA Astrophysics Data System (ADS)

    Scott, V.; Kettle, H.; Merchant, C. J.

    2010-12-01

    The sensitivity of the biological parameters in a nutrient-phytoplankton-zooplankton-detritus (NPZD) model in the calculation of the air-sea CO2 flux, primary production and detrital export is analysed. The NPZD model is the Hadley Centre Ocean Carbon Cycle model (HadOCC) from the UK Met Office, used in the Hadley Centre Coupled Model 3 (HadCM3) and FAst Met Office and Universities Simulator (FAMOUS) GCMs. Here, HadOCC is coupled to the 1-D General Ocean Turbulence Model (GOTM) and forced with European Centre for Medium-Range Weather Forecasting meteorology to undertake a sensitivity analysis of its twenty biological parameters. Analyses are performed at three sites in the EuroSITES European Ocean Observatory Network: the Central Irminger Sea (60° N 40° W), the Porcupine Abyssal Plain (49° N 16° W) and the European Station for Time series in the Ocean Canary Islands (29° N 15° W) to assess variability in parameter sensitivities at different locations in the North Atlantic Ocean. Reasonable changes to the values of key parameters are shown to have a large effect on the calculation of the air-sea CO2 flux, primary production, and export of biological detritus to the deep ocean. Changes in the values of key parameters have a greater effect in more productive regions than in less productive areas. We perform the analysis using one-at-a-time perturbations and using a statistical emulator, and compare results. The most sensitive parameters are generic to many NPZD ocean ecosystem models. The air-sea CO2 flux is most influenced by variation in the parameters that control phytoplankton growth, detrital sinking and carbonate production by phytoplankton (the rain ratio). Primary production is most sensitive to the parameters that define the shape of the photosythesis-irradiance curve. Export production is most sensitive to the parameters that control the rate of detrital sinking and the remineralisation of detritus.

  10. A stability dependent theory for air-sea gas exchange

    NASA Astrophysics Data System (ADS)

    Erickson, David J.

    1993-05-01

    The influence of thermal stability at the air-sea interface on computed values of the transfer velocities of trace gases is examined. The novel "whitecap" model for air-sea gas exchange of Monahan and Spillane (1984), extended here to include thermal stability effects, is linked with an atmospheric general circulation model to compute global transfer velocity patterns of a climate reactive gas, CO2. The important terms in the model equations such as the whitecap coverage, friction velocity, neutral and local drag coefficients and the stability parameter ψm(Z/L) are discussed and analyzed. The atmospheric surface level air temperature, relative humidity, wind speed and sea surface temperature, obtained from the National Center for Atmospheric Research Community Climate Model 1 (CCM1) are used to drive algorithms describing the air-sea transfer velocity of trace gases. The transfer velocity for CO2 (kCO2) is then computed for each 2.8° × 2.8° latitudinal-longitudinal area every 24 hours for 5 years of the seasonal-hydro runs of the CCM1. The new model results are compared to previously proposed formulations using the identical CCM1 forcing terms. Air-sea thermal stability effects on the transfer velocity for CO2 are most important at mid-high wind speeds. Where cold air from continental interiors is transported over relatively warm oceanic waters, the transfer velocities are enhanced over neutral stability values. The depression of computed kCO2 values when warm air resides over cold water is especially important, due to asymmetry in the stability dependence of the drag coefficient. The stability influence is 20% to 50% of kCO2 for modest air-sea temperature differences and up to 100% for extreme cases of stability or instability. The stability dependent "whitecap" model, using the transfer velocity coefficients for whitecap and nonwhitecap areas suggested by Monahan and Spillane (1984), produces CO2 transfer velocities that range from 13 to 50 cm h-1 for a

  11. Application of new parameterizations of gas transfer velocity and their impact on regional and global marine CO 2 budgets

    NASA Astrophysics Data System (ADS)

    Fangohr, Susanne; Woolf, David K.

    2007-06-01

    independently. We then apply our parameterization to a monthly TOPEX altimeter gridded 1.5° × 1.5° data set and compare our results to transfer velocities calculated using the popular wind-based k parameterizations by Wanninkhof [Wanninkhof, R., 1992. Relationship between wind speed and gas exchange over the ocean. J. Geophys. Res., 97: 7373-7382.] and Wanninkhof and McGillis [Wanninkhof, R. and McGillis, W., 1999. A cubic relationship between air-sea CO2 exchange and wind speed. Geophys. Res. Lett., 26(13): 1889-1892]. We show that despite good agreement of the globally averaged transfer velocities, global and regional fluxes differ by up to 100%. These discrepancies are a result of different spatio-temporal distributions of the processes involved in the parameterizations of k, indicating the importance of wave field parameters and a need for further validation.

  12. [Potentiometric method of analyzing CO2 transfer in a blood membrane oxygenator].

    PubMed

    Vishnevskiĭ, M E; Pronina, N P; Mikhaĭlov, A A

    1987-01-01

    The paper proposes a method of the CO2 transfer intensity analysis in membrane oxygenators of the "MOCT" type. The dependence of the CO2 elimination rate on the liquid flow and oxygen blow-down rates for various oxygenators have been studied on a closed loop circuit. It has been established that the elimination rate depends not only on the transfer through membrane and the liquid layer, but also on the CO2 hydration-dehydration rate.

  13. Upper ocean bubble measurements from the NE Pacific and estimates of their role in air-sea gas transfer of the weakly soluble gases nitrogen and oxygen

    NASA Astrophysics Data System (ADS)

    Vagle, Svein; McNeil, Craig; Steiner, Nadja

    2010-12-01

    Simultaneous observations of upper-ocean bubble clouds, and dissolved gaseous nitrogen (N2) and oxygen (O2) from three winter storms are presented and analyzed. The data were collected on the Canadian Surface Ocean Lower Atmosphere Study (C-SOLAS) mooring located near Ocean Station Papa (OSP) at 50°N, 145°W in the NE Pacific during winter of 2003/2004. The bubble field was measured using an upward looking 200 kHz echosounder. Direct estimates of bubble mediated gas fluxes were made using assumed bubble size spectra and the upward looking echosounder data. A one-dimensional biogeochemical model was used to help compare data and various existing models of bubble mediated air-sea gas exchange. The direct bubble flux calculations show an approximate quadratic/cubic dependence on mean bubble penetration depth. After scaling from N2/O2 to carbon dioxide, near surface, nonsupersaturating, air-sea transfer rates, KT, for U10 > 12 m s-1 fall between quadratic and cubic relationships. Estimates of the subsurface bubble induced air injection flux, VT, show an approximate quadratic/cubic dependence on mean bubble penetration depth. Both KT and VT are much higher than those measured during Hurricane Frances over the wind speed range 12 < U10 < 23 m s-1. This result implies that over the open ocean and this wind speed range, older and more developed seas which occur during winter storms are more effective in exchanging gases between the atmosphere and ocean than younger less developed seas which occur during the rapid passage of a hurricane.

  14. Transition from downward to upward air-sea momentum transfer in swell-dominated light wind condition

    NASA Astrophysics Data System (ADS)

    Smedman, Ann-Sofi; Högström, Ulf; Rutgersson, Anna

    2016-04-01

    Atmospheric and surface wave data from two oceanic experiments carried out on FLIP and ASIS platforms are analysed in order to identify swell-related effects on the momentum exchange during low wind speed conditions. The RED experiment was carried out on board an R/P Floating Instrument Platform, FLIP, anchored north east of the Hawaiian island Oahu with sonic anemometers at four levels: 5.1 m, 6.9 m, 9.9 m and 13.8 m respectively. The meteorological conditions were characterized by north- easterly trade wind and with swell present during most of the time. During swell the momentum flux was directed downwards meaning a positive contribution to the stress. The FETCH experiment was carried out in the Gulf of Lion in the north-western Mediterranean Sea. On the ASIS (air-sea interaction spar) buoy a sonic anemometer was mounted at 7 m above the mean surface level. During strong swell conditions the momentum flux was directed upwards meaning a negative contribution to the stress in this case. The downward momentum flux is shown to be a function of the orbital circulation while the upward momentum flux is a function of wave height. The dividing wind speed is found to be 3.5 m/s Conclusion: Wind speed > 3.5 m/s creates waves (ripples) and thus roughness. Combination of orbital motion and asymmetric structure of ripples lead to flow perturbation and downward transport of negative momentum. With low wind speed (no ripples but viscosity) circulations will form above the crest and the trough with opposite direction which will cause a pressure drop in the vertical direction and an upward momentum transport from the water to the air.

  15. Air-sea Energy Transfer at Mesoscale in a Coupled High-resolution Model: Impact of Resolution and Current Feedback

    NASA Astrophysics Data System (ADS)

    Jullien, S.; Colas, F.; Masson, S. G.; Oerder, V.; Echevin, V.; Samson, G.; Crétat, J.; Berthet, S.; Hourdin, C.

    2015-12-01

    Winds are usually considered to force the ocean but recent studies suggested that oceanic mesoscale activity, characterized by eddies, filaments and fronts, could also affect the wind field. These structures feature abrupt changes in sea surface temperature (SST), surface pressure and surface currents that could impact the atmosphere by enhancing/reducing air-sea fluxes, accelerating/decelerating winds, modifying the wind-pressure balance… At this time, the detailed processes associated to such coupling, its intensity and significance remain a matter of research. Here, a state-of-the-art WRF-OASIS-NEMO coupled model is set up over a wide tropical channel (45°S-45°N) at various resolutions: 3/4°, 1/4° and 1/12° in both the ocean and the atmosphere. Several experiments are conducted in forced, partially or fully coupled modes, to highlight the effect of resolution and the role of SST vs. current feedback to energy injection into the ocean and the atmosphere. In strong mesoscale activity regions, a negative wind power input from the atmosphere to the ocean is seen at scales ranging from 100km to more than 1000km. Nonexistent at 3/4°, this negative forcing, acting against oceanic mesoscale activity, is almost twice more important at 1/12° than at 1/4°. In addition, partially coupled simulations, i.e. without current feedback, show that the impact of thermal coupling on this process is very limited. Energy injection to the marine atmospheric boundary layer also features imprints from oceanic mesoscale. Energy injection by scales shorter than 300km represents up to 20% of the total. Finally we show that increasing oceanic resolution, and therefore mesoscale activity, is necessary to resolve the full wind stress spectrum and has an upscaling effect by enhancing atmospheric mesoscale, which is larger scale than in the ocean. Using 1/4°oceanic resolution instead of 1/12° leads to a 50% loss of energy in the atmospheric mesoscale.

  16. Evaporation in relation to CO 2 concentration: Analysis of mass transfer coefficient

    NASA Astrophysics Data System (ADS)

    Ojha, C. S. P.; Yasuda, Hiroshi; Rao, Surampalli; Abd Elbasit, Mohamed A. M.; Kumar, Manoj

    2011-11-01

    In this study, the potential of mass transfer approach in estimating evaporation changes under different CO 2 levels are evaluated using data from controlled chamber experiments in which radiation and wind velocity were kept constant and temperature and relative humidity profiles were varied in different patterns along with CO 2 concentration. Currently, FAO procedure lists three approaches to compute air vapour pressure based on temperature and relative humidity profiles. In this study, the impact of using different procedures of estimating air vapour pressure is examined to assess the use of mass transfer approach for estimating evaporation. To achieve this, a part of the data is used to calibrate mass transfer coefficient which is subsequently used to project evaporation for future states. Accordingly, strategies are ranked for their potential in estimating evaporation. The effect of evaporation rate is compared at 400 ppm and 600 ppm CO 2 level. It has been observed that the evaporation rate is more pronounced at higher CO 2 level.

  17. Pore-scale supercritical CO2 dissolution and mass transfer under drainage conditions

    NASA Astrophysics Data System (ADS)

    Chang, Chun; Zhou, Quanlin; Oostrom, Mart; Kneafsey, Timothy J.; Mehta, Hardeep

    2017-02-01

    Recently, both core- and pore-scale imbibition experiments have shown non-equilibrium dissolution of supercritical CO2 (scCO2) and a prolonged depletion of residual scCO2. In this study, pore-scale scCO2 dissolution and mass transfer under drainage conditions were investigated using a two-dimensional heterogeneous micromodel and a novel fluorescent water dye with a sensitive pH range between 3.7 and 6.5. Drainage experiments were conducted at 9 MPa and 40 °C by injecting scCO2 into the sandstone-analogue pore network initially saturated by water without dissolved CO2 (dsCO2). During the experiments, time-lapse images of dye intensity, reflecting water pH, were obtained. These images show non-uniform pH in individual pores and pore clusters, with average pH levels gradually decreasing with time. Further analysis on selected pores and pore clusters shows that (1) rate-limited mass transfer prevails with slowly decreasing pH over time when the scCO2-water interface area is low with respect to the volume of water-filled pores and pore clusters, (2) fast scCO2 dissolution and phase equilibrium occurs when scCO2 bubbles invade into water-filled pores, significantly enhancing the area-to-volume ratio, and (3) a transition from rate-limited to diffusion-limited mass transfer occurs in a single pore when a medium area-to-volume ratio is prevalent. The analysis also shows that two fundamental processes - scCO2 dissolution at phase interfaces and diffusion of dsCO2 at the pore scale (10-100 μm) observed after scCO2 bubble invasion into water-filled pores without pore throat constraints - are relatively fast. The overall slow dissolution of scCO2 in the millimeter-scale micromodel can be attributed to the small area-to-volume ratios that represent pore-throat configurations and characteristics of phase interfaces. This finding is applicable for the behavior of dissolution at pore, core, and field scales when water-filled pores and pore clusters of varying size are surrounded

  18. Parameterization of air sea gas fluxes at extreme wind speeds

    NASA Astrophysics Data System (ADS)

    McNeil, Craig; D'Asaro, Eric

    2007-06-01

    Hurricane Frances data set. Although all the model parameters cannot be determined uniquely, some features are clear. The fluxes due to the surface equilibration terms, estimated both from data and from model inversions, increase rapidly at high wind speed but are still far below those predicted using the cubic parameterization of Wanninkhof and McGillis [Wannikhof, R. and McGillis, W.R., 1999. A cubic relationship between air-sea CO 2 exchange and wind speed. Geophysical Research Letters, 26:1889-1892.] at high wind speed. The fluxes due to gas injection terms increase with wind speed even more rapidly, causing bubble injection to dominate at the highest wind speeds.

  19. Drive-Response Analysis of Global Ice Volume, CO2, and Insolation using Information Transfer

    NASA Astrophysics Data System (ADS)

    Brendryen, J.; Hannisdal, B.

    2014-12-01

    The processes and interactions that drive global ice volume variability and deglaciations are a topic of considerable debate. Here we analyze the drive-response relationships between data sets representing global ice volume, CO2 and insolation over the past 800 000 years using an information theoretic approach. Specifically, we use a non-parametric measure of directional information transfer (IT) based on the construct of transfer entropy to detect the relative strength and directionality of interactions in the potentially chaotic and non-linear glacial-interglacial climate system. Analyses of unfiltered data suggest a tight coupling between CO2 and ice volume, detected as strong, symmetric information flow consistent with a two-way interaction. In contrast, IT from Northern Hemisphere (NH) summer insolation to CO2 is highly asymmetric, suggesting that insolation is an important driver of CO2. Conditional analysis further suggests that CO2 is a dominant influence on ice volume, with the effect of insolation also being significant but limited to smaller-scale variability. However, the strong correlation between CO2 and ice volume renders them information redundant with respect to insolation, confounding further drive-response attribution. We expect this information redundancy to be partly explained by the shared glacial-interglacial "sawtooth" pattern and its overwhelming influence on the transition probability distributions over the target interval. To test this, we filtered out the abrupt glacial terminations from the ice volume and CO2 records to focus on the residual variability. Preliminary results from this analysis confirm insolation as a driver of CO2 and two-way interactions between CO2 and ice volume. However, insolation is reduced to a weak influence on ice volume. Conditional analyses support CO2 as a dominant driver of ice volume, while ice volume and insolation both have a strong influence on CO2. These findings suggest that the effect of orbital

  20. Direct measurements of the CO2 flux over the ocean: Development of a novel method

    NASA Astrophysics Data System (ADS)

    Prytherch, John; Yelland, Margaret J.; Pascal, Robin W.; Moat, Bengamin I.; Skjelvan, Ingunn; Neill, Craig C.

    2010-02-01

    Over the ocean, eddy correlation measurements of the air-sea CO2 flux obtained with open-path sensors have typically been an order of magnitude larger than those estimated by other techniques or sensors. It is shown here that this discrepancy is due to cross sensitivity to water vapor fluctuations: a novel correction procedure is demonstrated, tested against an independent data set and proved to be robust. After correction, the observed gas transfer velocities are in reasonable agreement with published values obtained using closed-path sensors or by tracer techniques. Data from open-path sensors may now be used for air-sea CO2 flux estimation, greatly increasing the information available on air-sea gas transfer velocity.

  1. Methods to reduce the CO(2) concentration of educational buildings utilizing internal ventilation by transferred air.

    PubMed

    Kalema, T; Viot, M

    2014-02-01

    The aim of this study is to develop internal ventilation by transferred air to achieve a good indoor climate with low energy consumption in educational buildings with constant air volume (CAV) ventilation. Both measurements of CO2 concentration and a multi-room calculation model are presented. The study analyzes how to use more efficiently the available spaces and the capacity of CAV ventilation systems in existing buildings and the impact this has on the indoor air quality and the energy consumption of the ventilation. The temperature differences can be used to create natural ventilation airflows between neighboring spaces. The behavior of temperature-driven airflows between rooms was studied and included in the calculation model. The effect of openings between neighboring spaces, such as doors or large apertures in the walls, on the CO2 concentration was studied in different classrooms. The air temperatures and CO2 concentrations were measured using a wireless, internet-based measurement system. The multi-room calculation model predicted the CO2 concentration in the rooms, which was then compared with the measured ones. Using transferred air between occupied and unoccupied spaces can noticeably reduce the total mechanical ventilation rates needed to keep a low CO2 concentration.

  2. The SOLAS air-sea gas exchange experiment (SAGE) 2004

    NASA Astrophysics Data System (ADS)

    Harvey, Mike J.; Law, Cliff S.; Smith, Murray J.; Hall, Julie A.; Abraham, Edward R.; Stevens, Craig L.; Hadfield, Mark G.; Ho, David T.; Ward, Brian; Archer, Stephen D.; Cainey, Jill M.; Currie, Kim I.; Devries, Dawn; Ellwood, Michael J.; Hill, Peter; Jones, Graham B.; Katz, Dave; Kuparinen, Jorma; Macaskill, Burns; Main, William; Marriner, Andrew; McGregor, John; McNeil, Craig; Minnett, Peter J.; Nodder, Scott D.; Peloquin, Jill; Pickmere, Stuart; Pinkerton, Matthew H.; Safi, Karl A.; Thompson, Rona; Walkington, Matthew; Wright, Simon W.; Ziolkowski, Lori A.

    2011-03-01

    The SOLAS air-sea gas exchange experiment (SAGE) was a multiple-objective study investigating gas-transfer processes and the influence of iron fertilisation on biologically driven gas exchange in high-nitrate low-silicic acid low-chlorophyll (HNLSiLC) Sub-Antarctic waters characteristic of the expansive subpolar zone of the southern oceans. This paper provides a general introduction and summary of the main experimental findings. The release site was selected from a pre-voyage desktop study of environmental parameters to be in the south-west Bounty Trough (46.5°S 172.5°E) to the south-east of New Zealand and the experiment was conducted between mid-March and mid-April 2004. In common with other mesoscale iron addition experiments (FeAX's), SAGE was designed as a Lagrangian study, quantifying key biological and physical drivers influencing the air-sea gas exchange processes of CO 2, DMS and other biogenic gases associated with an iron-induced phytoplankton bloom. A dual tracer SF 6/ 3He release enabled quantification of both the lateral evolution of a labelled volume (patch) of ocean and the air-sea tracer exchange at tenths of kilometer scale, in conjunction with the iron fertilisation. Estimates from the dual-tracer experiment found a quadratic dependency of the gas exchange coefficient on windspeed that is widely applicable and describe air-sea gas exchange in strong wind regimes. Within the patch, local and micrometeorological gas exchange process studies (100 m scale) and physical variables such as near-surface turbulence, temperature microstructure at the interface, wave properties and windspeed were quantified to further assist the development of gas exchange models for high-wind environments. There was a significant increase in the photosynthetic competence ( Fv/ Fm) of resident phytoplankton within the first day following iron addition, but in contrast to other FeAX's, rates of net primary production and column-integrated chlorophyll a concentrations had

  3. First principles derived, transferable force fields for CO2 adsorption in Na-exchanged cationic zeolites.

    PubMed

    Fang, Hanjun; Kamakoti, Preeti; Ravikovitch, Peter I; Aronson, Matthew; Paur, Charanjit; Sholl, David S

    2013-08-21

    The development of accurate force fields is vital for predicting adsorption in porous materials. Previously, we introduced a first principles-based transferable force field for CO2 adsorption in siliceous zeolites (Fang et al., J. Phys. Chem. C, 2012, 116, 10692). In this study, we extend our approach to CO2 adsorption in cationic zeolites which possess more complex structures. Na-exchanged zeolites are chosen for demonstrating the approach. These methods account for several structural complexities including Al distribution, cation positions and cation mobility, all of which are important for predicting adsorption. The simulation results are validated with high-resolution experimental measurements of isotherms and microcalorimetric heats of adsorption on well-characterized materials. The choice of first-principles method has a significant influence on the ability of force fields to accurately describe CO2-zeolite interactions. The PBE-D2 derived force field, which performed well for CO2 adsorption in siliceous zeolites, does not do so for Na-exchanged zeolites; the PBE-D2 method overestimates CO2 adsorption energies on multi-cation sites that are common in cationic zeolites with low Si/Al ratios. In contrast, a force field derived from the DFT/CC method performed well. Agreement was obtained between simulation and experiment not only for LTA-4A on which the force field fitting is based, but for other two common adsorbents, NaX and NaY.

  4. Inhibited proton transfer enhances Au-catalyzed CO2-to-fuels selectivity

    PubMed Central

    Wuttig, Anna; Yaguchi, Momo; Motobayashi, Kenta; Osawa, Masatoshi; Surendranath, Yogesh

    2016-01-01

    CO2 reduction in aqueous electrolytes suffers efficiency losses because of the simultaneous reduction of water to H2. We combine in situ surface-enhanced IR absorption spectroscopy (SEIRAS) and electrochemical kinetic studies to probe the mechanistic basis for kinetic bifurcation between H2 and CO production on polycrystalline Au electrodes. Under the conditions of CO2 reduction catalysis, electrogenerated CO species are irreversibly bound to Au in a bridging mode at a surface coverage of ∼0.2 and act as kinetically inert spectators. Electrokinetic data are consistent with a mechanism of CO production involving rate-limiting, single-electron transfer to CO2 with concomitant adsorption to surface active sites followed by rapid one-electron, two-proton transfer and CO liberation from the surface. In contrast, the data suggest an H2 evolution mechanism involving rate-limiting, single-electron transfer coupled with proton transfer from bicarbonate, hydronium, and/or carbonic acid to form adsorbed H species followed by rapid one-electron, one-proton, or H recombination reactions. The disparate proton coupling requirements for CO and H2 production establish a mechanistic basis for reaction selectivity in electrocatalytic fuel formation, and the high population of spectator CO species highlights the complex heterogeneity of electrode surfaces under conditions of fuel-forming electrocatalysis. PMID:27450088

  5. Radiative transfer in CO2-rich atmospheres: 1. Collisional line mixing implies a colder early Mars

    NASA Astrophysics Data System (ADS)

    Ozak, N.; Aharonson, O.; Halevy, I.

    2016-06-01

    Fast and accurate radiative transfer methods are essential for modeling CO2-rich atmospheres, relevant to the climate of early Earth and Mars, present-day Venus, and some exoplanets. Although such models already exist, their accuracy may be improved as better theoretical and experimental constraints become available. Here we develop a unidimensional radiative transfer code for CO2-rich atmospheres, using the correlated k approach and with a focus on modeling early Mars. Our model differs from existing models in that it includes the effects of CO2 collisional line mixing in the calculation of the line-by-line absorption coefficients. Inclusion of these effects results in model atmospheres that are more transparent to infrared radiation and, therefore, in colder surface temperatures at radiative-convective equilibrium, compared with results of previous studies. Inclusion of water vapor in the model atmosphere results in negligible warming due to the low atmospheric temperatures under a weaker early Sun, which translate into climatically unimportant concentrations of water vapor. Overall, the results imply that sustained warmth on early Mars would not have been possible with an atmosphere containing only CO2 and water vapor, suggesting that other components of the early Martian climate system are missing from current models or that warm conditions were not long lived.

  6. Non-catalytic transfer hydrogenation in supercritical CO2 for coal liquefaction

    NASA Astrophysics Data System (ADS)

    Elhussien, Hussien

    This thesis presents the results of the investigation on developing and evaluating a low temperature (<150°C) non - catalytic process using a hydrogen transfer agent (instead of molecu-lar hydrogen) for coal dissolution in supercritical CO2. The main idea behind the thesis was that one hydrogen atom from water and one hydrogen atom from the hydrogen transfer agent (HTA) were used to hydrogenate the coal. The products of coal dissolution were non-polar and polar while the supercritical CO2, which enhanced the rates of hydrogenation and dissolution of the non-polar molecules and removal from the reaction site, was non-polar. The polar modifier (PM) for CO2 was added to the freed to aid in the dissolution and removal of the polar components. The addition of a phase transfer agent (PTA) allowed a seamless transport of the ions and by-product between the aqueous and organic phases. DDAB, used as the PTA, is an effective phase transfer catalyst and showed enhancement to the coal dissolution process. COAL + DH- +H 2O → COAL.H2 + DHO-- This process has a great feature due to the fact that the chemicals were obtained without requir-ing to first convert coal to CO and H2 units as in indirect coal liquefaction. The experiments were conducted in a unique reactor set up that can be connected through two lines. one line to feed the reactor with supercritical CO 2 and the other connected to gas chromatograph. The use of the supercritical CO2 enhanced the solvent option due to the chemical extraction, in addition to the low environmental impact and energy cost. In this thesis the experiment were conducted at five different temperatures from atmos-pheric to 140°C, 3000 - 6000 psi with five component of feed mixture, namely water, HTA, PTA, coal, and PM in semi batch vessels reactor system with a volume of 100 mL. The results show that the chemicals were obtained without requiring to first convert coal to CO and H2 units as in indirect coal liquefaction. The results show that

  7. The Effect of Oil Contamination on Evaporator Heat Transfer Characteristics of CO2 Refrigeration Cycle

    NASA Astrophysics Data System (ADS)

    Katsuta, Masafumi; Kinpara, Hiromitsu; Yagi, Shunta; Mukaiyama, Hiroshi

    Because of the destructions of ozone layers and global warming, it is urgently necessary to abolish fluorocarbon refrigerants of HFCs and substitute them with natural refrigerants. Among several choices of natural refrigerants, CO2, which has an excellent thermal property, has the advantage for practical application. However, heat transfer coefficient and pressure drop of evaporator have not studied enough. No available correlation has been established. The refrigerant of CO2 is extremely sensitive to oil. Therefore, the research on the refrigerant under the circumstances that it is mixed with oil is very limited. It is the purpose of this research to examine the oil mixing effects on thermal and fluid dynamic behaviors and establish correlation.

  8. Supercritical CO2 Dissolution and Mass Transfer in a Heterogeneous Pore Network under Drainage and Imbibition Conditions

    NASA Astrophysics Data System (ADS)

    Kneafsey, T. J.; Chang, C.; Zhou, Q.; Oostrom, M.; Wietsma, T. W.; Yu, Q.

    2015-12-01

    Dissolution trapping of supercritical CO2 (scCO2) is usually modeled by assuming instantaneous scCO2 dissolution and equilibrium phase partitioning. Our recent core-scale imbibition experiments show a prolonged depletion of residual scCO2 by dissolution, implying a non-equilibrium mechanism. In our 2D sandstone-analogue micromodel experimental study, pore-scale scCO2 dissolution was inferred from imaging (1) drainage using a pH-sensitive water dye and (2) imbibition using a scCO2 dye. The drainage experiment was conducted by injecting scCO2 into the dissolved-CO2 (dsCO2)-free water-filled pore network. The time-lapse images of non-uniform dye intensities indicating varying pH show that dsCO2 concentration varies from zero to solubility in individual pores and pore clusters and the average concentration gradually increases with time. The different rates of dissolution in different pores/clusters can be attributed to (1) fast scCO2 dissolution at scCO2-water interfaces, (2) rate-limited mass transfer due to limited interface areas, and (3) a transition from rate-limited to diffusion-limited mass transfer, revealed by detailed analysis on selected pores and pore clusters. The imbibition experiments conducted by injecting deionized water at different rates show (1) water flow in channels bypassing scCO2 at high residual saturations, (2) subsequent, slow scCO2 depletion by dissolution and mass transfer as effluent dsCO2 concentration varies from 0.06% to 4.44% of solubility, and (3) creation of new water flow paths by dissolution, enhancing scCO2 depletion by coupled displacement and dissolution. Both the drainage and imbibitions experiments indicate non-equilibrium scCO2 dissolution in the centimeter-scale pore network over 4.5 hours and up to 14 hours, respectively. The pore-scale imaging can help better understand the effects of pore-throat characteristics on scCO2 dissolution and mass transfer during drainage and imbibition and the interplay between displacement and

  9. A method for mapping regional oxygen and CO2 transfer in the lung.

    PubMed

    Johansen, Troels; Winkler, Tilo; Kelly, Vanessa Jane; Osorio-Valencia, Juan Sebastian; Greenblatt, Elliot Eliyahu; Harris, Robert Scott; Venegas, Jose Gabriel

    2016-02-01

    This paper presents a novel approach to visualizing regional lung function, through quantitative three-dimensional maps of O2 and CO2 transfer rates. These maps describe the contribution of anatomical regions to overall gas exchange and demonstrate how transfer rates of the two gas species' differ regionally. An algorithm for generating such maps is presented, and for illustration, regional gas transfer maps were generated using values of ventilation and perfusion imaged by PET/CT for a healthy subject and an asthmatic patient after bronchoprovocation. In a sensitivity analysis, compartment values of gas transfer showed minor sensitivity to imaging noise in the ventilation and perfusion data, and moderate sensitivity to estimation errors in global lung input values, chiefly global alveolar ventilation, followed by cardiac output and arterial-venous O2 content difference. Gas transfer maps offer an intuitive display of physiologically relevant lung function at a regional level, the potential for an improved understanding of pulmonary gas exchange in health and disease, and potentially a presurgical evaluation tool.

  10. Influence of surface kinematics on air-sea heat flux

    NASA Astrophysics Data System (ADS)

    Veron, Fabrice; Melville, Ken

    2004-11-01

    The top few meters of the oceanic boundary layer play a critical role in the transfers of momentum, gas, mass and heat between the atmosphere and the ocean. These exchanges must necessarily transfer through the surface, and presumably, the rates at which they do are influence by the dynamics of the surface layer. Heat flux in particular is regulated by the thin surface thermal layer which, at most, is only a few millimeter thick. We are specifically interested in the influence of small coherent structures of the surface turbulence on the heat flux. Using active and passive infrared imaging, we measured the evolution the surface velocity and temperature fields over small areas of a few square meters. High-resolution surface Eulerian velocity fields using cross-correlation techniques (PIV) are obtained. Using active marking of the surface with an infrared CO2 laser, we have not only shown that it is possible to directly recover the Langrangian surface velocity, but also, by marking appropriate patterns on the surface we have been able to measure the shear strain, vorticity, and surface divergence. With the penetration depth of infrared radiation at these wavelengths being a few microns, these techniques appear to be quite apt for direct measurements of ocean surface turbulence. We have also found that the flux of heat through the surface appears to be influenced by the surface wave field. We will discuss the results in the context of air sea heat flux and ocean surface turbulence.

  11. Charge transfer behavior of graphene-titania photoanode in CO2 photoelectrocatalysis process

    NASA Astrophysics Data System (ADS)

    Hasan, Md. Rakibul; Hamid, Sharifah Bee Abd; Basirun, Wan Jeffrey

    2015-06-01

    In the present study, a graphene-titania composite photoelectrode was synthesized, characterized and examined for the photoelectrocatalytic (PEC) response. The charge transfer process on the semiconductor/electrolyte interface was investigated via electrochemical impedance spectroscopy (EIS) and voltammetry. In addition, the influence of pH toward the photoanode performance was also investigated and it was noticed that a high pH condition was favorable higher photocurrent response from the EIS measurements. The main reason could be attributed to the decrease of recombination process at the photoanode with fast quenching of the photogenerated holes with OH- ions at high pH. The experiment was also run for CO2 photoreduction and increased photocurrent was observed.

  12. Energy Transfer Collisional Process Involving Heteromolecular Collisions Between Methyl Fluoride and N_2, Ar, He, CO_2, and Air

    NASA Astrophysics Data System (ADS)

    Phillips, Dane J.; Everitt, Henry O.

    2013-06-01

    Time resolved IR/THz double resonance (DR) spectroscopy has been performed with a Q-switched CO_2 laser and heterodyne THz detection. The rate constants associated with allowed rotational- and vibrational-state changing collisions of CH_3F with N_2, Ar, He, CO_2, and air are measured by monitoring the temporal evolution of the absorption strength for numerous rotational transitions as a function of pressure. Collision partner dependent energy transfer processes are studied and compared with homomolecular collisions. Energy transfer maps and associated collisional cross sections will be presented for each collision partner.

  13. An efficient system for carbonation of high-rate algae pond water to enhance CO2 mass transfer.

    PubMed

    Putt, Ron; Singh, Manjinder; Chinnasamy, Senthil; Das, K C

    2011-02-01

    High-rate algal ponds have the potential to produce 59 T of dry biomass ha(-1)year(-1) based on the specific productivity of 20 g m(-2) day(-1). Atmospheric air provides only 5% of the CO(2) to the pond surface required for photosynthesis. Hence, CO(2) is usually provided via bubbling of concentrated CO(2)-air mixture into the algae ponds. This process is, however, not significantly effective in terms of mass transfer. Use of bubble column to increase the interfacial area of contact available for gas exchange is proposed as an efficient alternative. A carbonation column (CC) was modeled and designed to measure CO(2) absorptivity in-pond water at various pH regimes. The CC performed at 83% CO(2) transfer efficiency. An air-to-pond mass transport coefficient of 0.0037 m min(-1) was derived. The proposed device can be used with any exhaust gas stream with higher concentrations of CO(2) in conjunction with raceways for optimizing algae production.

  14. Pore-scale supercritical CO2 dissolution and mass transfer under imbibition conditions

    NASA Astrophysics Data System (ADS)

    Chang, Chun; Zhou, Quanlin; Kneafsey, Timothy J.; Oostrom, Mart; Wietsma, Thomas W.; Yu, Qingchun

    2016-06-01

    In modeling of geological carbon storage, dissolution of supercritical CO2 (scCO2) is often assumed to be instantaneous with equilibrium phase partitioning. In contrast, recent core-scale imbibition experiments have shown a prolonged depletion of residual scCO2 by dissolution, implying a non-equilibrium mechanism. In this study, eight pore-scale scCO2 dissolution experiments in a 2D heterogeneous, sandstone-analog micromodel were conducted at supercritical conditions (9 MPa and 40 °C). The micromodel was first saturated with deionized (DI) water and drained by injecting scCO2 to establish a stable scCO2 saturation. DI water was then injected at constant flow rates after scCO2 drainage was completed. High resolution time-lapse images of scCO2 and water distributions were obtained during imbibition and dissolution, aided by a scCO2-soluble fluorescent dye introduced with scCO2 during drainage. These images were used to estimate scCO2 saturations and scCO2 depletion rates. Experimental results show that (1) a time-independent, varying number of water-flow channels are created during imbibition and later dominant dissolution by the random nature of water flow at the micromodel inlet, and (2) a time-dependent number of water-flow channels are created by coupled imbibition and dissolution following completion of dominant imbibition. The number of water-flow paths, constant or transient in nature, greatly affects the overall depletion rate of scCO2 by dissolution. The average mass fraction of dissolved CO2 (dsCO2) in water effluent varies from 0.38% to 2.72% of CO2 solubility, indicating non-equilibrium scCO2 dissolution in the millimeter-scale pore network. In general, the transient depletion rate decreases as trapped, discontinuous scCO2 bubbles and clusters within water-flow paths dissolve, then remains low with dissolution of large bypassed scCO2 clusters at their interfaces with longitudinal water flow, and finally increases with coupled transverse water flow and

  15. Pore-scale supercritical CO2 dissolution and mass transfer under imbibition conditions

    SciTech Connect

    Chang, Chun; Zhou, Quanlin; Kneafsey, Timothy J.; Oostrom, Mart; Wietsma, Thomas W.; Yu, Qingchun

    2016-06-01

    In modeling of geological carbon storage, dissolution of supercritical CO2 (scCO2) is often assumed to be instantaneous with equilibrium phase partitioning. In contrast, recent core-scale imbibition experiments have shown a prolonged depletion of residual scCO2 by dissolution, implying a non-equilibrium mechanism. In this study, eight pore-scale scCO2 dissolution experiments in a 2D heterogeneous, sandstone-analogue micromodel were conducted at supercritical conditions (9 MPa and 40 °C). The micromodel was first saturated with deionized (DI) water and drained by injecting scCO2 to establish a stable scCO2 saturation. DI water was then injected at constant flow rates after scCO2 drainage was completed. High resolution time-lapse images of scCO2 and water distributions were obtained during imbibition and dissolution, aided by a scCO2-soluble fluorescent dye introduced with scCO2 during drainage. These images were used to estimate scCO2 saturations and scCO2 depletion rates. Experimental results show that (1) a time-independent, varying number of water-flow channels are created during imbibition and later dominant dissolution by the random nature of water flow at the micromodel inlet, and (2) a time-dependent number of water-flow channels are created by coupled imbibition and dissolution following completion of dominant imbibition. The number of water-flow paths, constant or transient in nature, greatly affects the overall depletion rate of scCO2 by dissolution. The average mass fraction of dissolved CO2 (dsCO2) in water effluent varies from 0.38% to 2.72% of CO2 solubility, indicating non-equilibrium scCO2 dissolution in the millimeter-scale pore network. In general, the transient depletion rate decreases as trapped, discontinuous scCO2 bubbles and clusters within water-flow paths dissolve, then remains low with dissolution of large bypassed scCO2 clusters at their interfaces with longitudinal water flow, and finally increases with coupled transverse water flow and

  16. Phase Transfer-Catalyzed Fast CO2 Absorption by MgO-Based Absorbents with High Cycling Capacity

    SciTech Connect

    Zhang, Keling; Li, Xiaohong S.; Li, Weizhen; Rohatgi, Aashish; Duan, Yuhua; Singh, Prabhakar; Li, Liyu; King, David L.

    2014-06-01

    CO2 capture from pre-combustion syngas in the temperature range of 250-400°C is highly desirable from an energy efficiency perspective. Thermodynamically, MgO is a promising material for CO2 capture, but the gas-solid reaction to produce MgCO3 is kinetically slow due to high lattice energy. We report here fast CO2 absorption over a solid MgO-molten nitrate/nitrite aggregate through phase transfer catalysis, in which the molten phase serves as both a catalyst and reaction medium. Reaction with CO2 at the gas-solid-liquid triple phase boundary results in formation of MgCO3 with significant reaction rate and a high conversion of MgO. This methodology is also applicable to other alkaline earth oxides, inspiring the design of absorbents which require activation of the bulk material.

  17. Population transfer collisions involving nD Rydberg atoms in a CO2 optical dipole trap

    NASA Astrophysics Data System (ADS)

    Kondo, Jorge M.; Goncalves, Luis F.; Tallant, Jonathan E.; Marcassa, Luis G.

    2014-05-01

    There has been an increasing interest in cold Rydberg atoms over the last several years. The primary reason for this attention is that interactions between Rydberg atoms are strong and lead to many interesting and useful phenomena, which require high atomic density samples. In this work, we have loaded Rb atoms into a CO2 optical dipole trap. After the loading, we turn off the dipole trap and excite the Rydberg state using a combination of two cw laser beams at 780 nm and 480 nm respectively. Finally, the Rydberg atoms are detected using pulsed field ionization technique. By analyzing the electrons signal, we can study the population transfer from the nD state to the (n + 2)P as a function of the atomic density for 37 <= n <= 45. As the atomic density increases, the excitation of the nD state saturates, suggesting the occurrence of dipole blockade. Nevertheless, the (n + 2)P is quadratically proportional to the nD population. We have also investigated the role of a dc electrical field in such process. This work was supported by Fapesp and INCT-IQ.

  18. Surfactant control of air-sea gas exchange across contrasting biogeochemical regimes

    NASA Astrophysics Data System (ADS)

    Pereira, Ryan; Schneider-Zapp, Klaus; Upstill-Goddard, Robert

    2014-05-01

    Air-sea gas exchange is important to the global partitioning of CO2.Exchange fluxes are products of an air-sea gas concentration difference, ΔC, and a gas transfer velocity, kw. The latter is controlled by the rate of turbulent diffusion at the air-sea interface but it cannot be directly measured and has a high uncertainty that is now considered one of the greatest challenges to quantifying net global air-sea CO2 exchange ...(Takahashi et al., 2009). One important control on kw is exerted by sea surface surfactants that arise both naturally from biological processes and through anthropogenic activity. They influence gas exchange in two fundamental ways: as a monolayer physical barrier and through modifying sea surface hydrodynamics and hence turbulent energy transfer. These effects have been demonstrated in the laboratory with artificial surfactants ...(Bock et al., 1999; Goldman et al., 1988) and through purposeful surfactant releases in coastal waters .(.).........().(Brockmann et al., 1982) and in the open ocean (Salter et al., 2011). Suppression of kwin these field experiments was ~5-55%. While changes in both total surfactant concentration and the composition of the natural surfactant pool might be expected to impact kw, the required in-situ studies are lacking. New data collected from the coastal North Sea in 2012-2013 shows significant spatio-temporal variability in the surfactant activity of organic matter within the sea surface microlayer that ranges from 0.07-0.94 mg/L T-X-100 (AC voltammetry). The surfactant activities show a strong winter/summer seasonal bias and general decrease in concentration with increasing distance from the coastline possibly associated with changing terrestrial vs. phytoplankton sources. Gas exchange experiments of this seawater using a novel laboratory tank and gas tracers (CH4 and SF6) demonstrate a 12-45% reduction in kw compared to surfactant-free water. Seasonally there is higher gas exchange suppression in the summer

  19. The impact of porosity waves on crustal reaction progress and CO2 mass transfer

    NASA Astrophysics Data System (ADS)

    Tian, Meng; Ague, Jay J.

    2014-03-01

    Rocks below the brittle-ductile transition can deform viscously and compact while fluid percolates through (two-phase solid-fluid flow). We investigate chemical reaction systematics during two-phase flow using one-dimensional numerical models in which reactive H2O-CO2 fluid ascends down-temperature toward the surface, driving the retrograde reaction: 7CO2+3Calcite+Tremolite=5Dolomite+8Quartz+H2O. The reaction progress is compared to that predicted by fluid-rock reaction during “standard” Darcian flow. A range of layer thicknesses (km-scale) in one- and two-layer systems were investigated at pressure-temperature conditions below the brittle-ductile transition corresponding to ∼13-20 km depth. Model porosity waves of wavelength ∼5 km were generated repeatedly at the base of the flow region using a solitary wave solution with a prescribed initial wave amplitude A = (maximum porosity)/(background porosity of 10-3). Simulation of reaction progress and carbon transfer for the Darcian flow model and for porosity wave transport with A=5, 2.5 and 1.25 yield the following results. First, the overall reaction progress in the two fluid transport models is mainly controlled by the time-integrated fluid flux, and is not strongly dependent on the flow regime. The implication is that the fluid pressure gradient anomalies in the regional-scale porosity waves modeled herein play a negligible role in driving reaction progress. Second, although there are high fluid velocities and thus strong advection in large amplitude porosity waves, the kinetic parameters adopted from experiments predict that the fluid compositions approach local fluid-rock equilibrium in both transport models. Third, regional-scale carbonate-bearing rock layers may be substantial sinks for carbon in ascending fluids if sufficient porosity and permeability can be maintained during reaction. Finally, typical models of retrograde reactions predict that porosity ultimately becomes clogged and, thus, fluid flow

  20. Study of metal transfer in CO2 laser+GMAW-P hybrid welding using argon-helium mixtures

    NASA Astrophysics Data System (ADS)

    Zhang, Wang; Hua, Xueming; Liao, Wei; Li, Fang; Wang, Min

    2014-03-01

    The metal transfer in CO2 Laser+GMAW-P hybrid welding by using argon-helium mixtures was investigated and the effect of the laser on the mental transfer is discussed. A 650 nm laser, in conjunction with the shadow graph technique, is used to observe the metal transfer process. In order to analyze the heat input to the droplet and the droplet internal current line distribution. An optical emission spectroscopy system was employed to estimate default parameter and optimized plasma temperature, electron number densities distribution. The results indicate that the CO2 plasma plume have a significant impact to the electrode melting, droplet formation, detachment, impingement onto the workpiece and weld morphology. Since the current distribution direction flow changes to the keyhole, to obtain a metal transfer mode of one droplet per pulse, the welding parameters should be adjusted to a higher pulse time (TP) and a lower voltage.

  1. Modeling of mass transfer of Phospholipids in separation process with supercritical CO2 fluid by RBF artificial neural networks

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An artificial Radial Basis Function (RBF) neural network model was developed for the prediction of mass transfer of the phospholipids from canola meal in supercritical CO2 fluid. The RBF kind of artificial neural networks (ANN) with orthogonal least squares (OLS) learning algorithm were used for mod...

  2. Molecular structures and excited states of CpM(CO)(2) (Cp = eta(5)-C(5)H(5); M = Rh, Ir) and [Cl(2)Rh(CO)(2)](-). Theoretical evidence for a competitive charge transfer mechanism.

    PubMed

    Hu, Zhenming; Boyd, Russell J; Nakatsuji, Hiroshi

    2002-03-20

    Molecular structures and excited states of CpM(CO)(2) (Cp = eta(5)-C(5)H(5); M = Rh, Ir) and [Cl(2)Rh(CO)(2)](-) complexes have been investigated using the B3LYP and the symmetry-adapted cluster (SAC)/SAC-configuration interaction (SAC-CI) theoretical methods. All the dicarbonyl complexes have singlet ground electronic states with large singlet-triplet separations. Thermal dissociations of CO from the parent dicarbonyls are energetically unfavorable. CO thermal dissociation is an activation process for [Cl(2)Rh(CO)(2)](-) while it is a repulsive potential for CpM(CO)(2). The natures of the main excited states of CpM(CO)(2) and [Cl(2)Rh(CO)(2)](-) are found to be quite different. For [Cl(2)Rh(CO)(2)](-), all the strong transitions are identified to be metal to ligand CO charge transfer (MLCT) excitations. A significant feature of the excited states of CpM(CO)(2) is that both MLCT excitation and a ligand Cp to metal and CO charge transfer excitation are strongly mixed in the higher energy states with the latter having the largest oscillator strength. A competitive charge transfer excited state has therefore been identified theoretically for CpRh(CO)(2) and CpIr(CO)(2). The wavelength dependence of the quantum efficiencies for the photoreactions of CpM(CO)(2) reported by Lees et al. can be explained by the existence of two different types of excited states. The origin of the low quantum efficiencies for the C-H/S-H bond activations of CpM(CO)(2) can be attributed to the smaller proportion of the MLCT excitation in the higher energy states.

  3. Gas transfer in dogfish: a unique model of CO2 excretion.

    PubMed

    Gilmour, K M; Perry, S F

    2010-04-01

    Carbonic anhydrase (CA) is a zinc metalloenzyme that catalyzes the reversible hydration-dehydration reactions of CO(2). It is present in high abundance in the cytoplasm of vertebrate red blood cells, where it contributes to CO(2) excretion. A membrane-bound CA isoform (CA IV) is also present in the lungs of mammals and reptiles, but plays little role in CO(2) excretion. The gills of teleost fish appear to lack plasma-accessible CA activity. In elasmobranchs, however, evidence gathered using a variety of physiological, biochemical and molecular approaches suggests that CA IV is present in the gills, and that at least in dogfish, this CA IV makes a significant contribution to CO(2) excretion by catalyzing the dehydration of plasma HCO(3)(-). The contribution of CA IV to CO(2) excretion is favoured by unusually high relative plasma buffering that aids in the provision of protons for HCO(3)(-) dehydration. Moreover, reduced emphasis on HCO(3)(-) flux through the red blood cell may reflect the occurrence of a slower turnover cytosolic CA in dogfish. This model of CO(2) excretion, in which HCO(3)(-) dehydration in the red blood cell catalyzed by cytosolic CA and HCO(3)(-) dehydration in the plasma catalyzed by membrane-bound CA IV are of comparable importance, has been described for the dogfish. Further work is required to determine whether it applies to elasmobranch fish as a group.

  4. Influence of O-CO2 and O-NO Vibrational Energy Transfer on Thermospheric Density and Satellite Drag Predictions

    NASA Astrophysics Data System (ADS)

    Dodd, J. A.; Sharma, R. D.; Hwang, E. S.; Castle, K. J.

    2001-12-01

    Collisions of O with the trace species CO2 and NO provide significant atmospheric cooling in the Earth's upper mesosphere-lower thermosphere, between 70 and 200 km. These collisions efficiently populate CO2(ν 2) and NO(v=1), respectively, converting a portion of the ambient kinetic energy into 15-μ m and 5.3-μ m IR emission. Much of the emission escapes into space, effectively removing ambient kinetic energy from the atmosphere. In recent years our group has performed laboratory measurements to better characterize the vibrational energy transfer (VET) efficiencies for the NO-O system, and is currently developing techniques for studying VET in the CO2-O system. These results, together with TIME-GCM modeling, show that predictions of upper atmospheric temperature and density are sensitive to the values assumed for the NO-O and CO2-O VET efficiencies, including their temperature dependence. The predicted cooling rates may either add or compensate, depending on the atmospheric conditions and on the kinetic parameters used in the photochemical model. In particular, the large CO2-O VET efficiency and increasing global CO2 concentrations suggest that the thermosphere may be cooling and contracting over time. This hypothesis is supported by a limited number of analyses of satellite orbital motion, as well as variation in polar mesospheric cloud and ion layer altitudes implied by recent observations. This has important implications for photochemical models, radiance predictions, and for spacecraft drag and satellite longevity. It also provides an interesting connection between a molecular-level parameter, the CO2-O VET efficiency, and the macroscopic effects of atmospheric density and satellite drag.

  5. Numerical Studies of Fluid Leakage from a Geologic DisposalReservoir for CO2 Show Self-Limiting Feedback between Fluid Flow and HeatTransfer

    SciTech Connect

    Pruess, Karsten

    2005-03-22

    Leakage of CO2 from a hypothetical geologic storage reservoir along an idealized fault zone has been simulated, including transitions between supercritical, liquid, and gaseous CO2. We find strong non-isothermal effects due to boiling and Joule-Thomson cooling of expanding CO2. Leakage fluxes are limited by limitations in conductive heat transfer to the fault zone. The interplay between multiphase flow and heat transfer effects produces non-monotonic leakage behavior.

  6. Heat Transfer and Fluid Transport of Supercritical CO2 in Enhanced Geothermal System with Local Thermal Non-equilibrium Model

    DOE PAGES

    Zhang, Le; Luo, Feng; Xu, Ruina; ...

    2014-12-31

    The heat transfer and fluid transport of supercritical CO2 in enhanced geothermal system (EGS) is studied numerically with local thermal non-equilibrium model, which accounts for the temperature difference between solid matrix and fluid components in porous media and uses two energy equations to describe heat transfer in the solid matrix and in the fluid, respectively. As compared with the previous results of our research group, the effect of local thermal non-equilibrium mainly depends on the volumetric heat transfer coefficient ah, which has a significant effect on the production temperature at reservoir outlet and thermal breakthrough time. The uniformity of volumetricmore » heat transfer coefficient ah has little influence on the thermal breakthrough time, but the temperature difference become more obvious with time after thermal breakthrough with this simulation model. The thermal breakthrough time reduces and the effect of local thermal non-equilibrium becomes significant with decreasing ah.« less

  7. High resolution IR diode laser study of collisional energy transfer between highly vibrationally excited monofluorobenzene and CO2: the effect of donor fluorination on strong collision energy transfer.

    PubMed

    Kim, Kilyoung; Johnson, Alan M; Powell, Amber L; Mitchell, Deborah G; Sevy, Eric T

    2014-12-21

    Collisional energy transfer between vibrational ground state CO2 and highly vibrationally excited monofluorobenzene (MFB) was studied using narrow bandwidth (0.0003 cm(-1)) IR diode laser absorption spectroscopy. Highly vibrationally excited MFB with E' = ∼41,000 cm(-1) was prepared by 248 nm UV excitation followed by rapid radiationless internal conversion to the electronic ground state (S1→S0*). The amount of vibrational energy transferred from hot MFB into rotations and translations of CO2 via collisions was measured by probing the scattered CO2 using the IR diode laser. The absolute state specific energy transfer rate constants and scattering probabilities for single collisions between hot MFB and CO2 were measured and used to determine the energy transfer probability distribution function, P(E,E'), in the large ΔE region. P(E,E') was then fit to a bi-exponential function and extrapolated to the low ΔE region. P(E,E') and the biexponential fit data were used to determine the partitioning between weak and strong collisions as well as investigate molecular properties responsible for large collisional energy transfer events. Fermi's Golden rule was used to model the shape of P(E,E') and identify which donor vibrational motions are primarily responsible for energy transfer. In general, the results suggest that low-frequency MFB vibrational modes are primarily responsible for strong collisions, and govern the shape and magnitude of P(E,E'). Where deviations from this general trend occur, vibrational modes with large negative anharmonicity constants are more efficient energy gateways than modes with similar frequency, while vibrational modes with large positive anharmonicity constants are less efficient at energy transfer than modes of similar frequency.

  8. Increased litterfall in tropical forests boosts the transfer of soil CO2 to the atmosphere.

    PubMed

    Sayer, Emma J; Powers, Jennifer S; Tanner, Edmund V J

    2007-12-12

    Aboveground litter production in forests is likely to increase as a consequence of elevated atmospheric carbon dioxide (CO(2)) concentrations, rising temperatures, and shifting rainfall patterns. As litterfall represents a major flux of carbon from vegetation to soil, changes in litter inputs are likely to have wide-reaching consequences for soil carbon dynamics. Such disturbances to the carbon balance may be particularly important in the tropics because tropical forests store almost 30% of the global soil carbon, making them a critical component of the global carbon cycle; nevertheless, the effects of increasing aboveground litter production on belowground carbon dynamics are poorly understood. We used long-term, large-scale monthly litter removal and addition treatments in a lowland tropical forest to assess the consequences of increased litterfall on belowground CO(2) production. Over the second to the fifth year of treatments, litter addition increased soil respiration more than litter removal decreased it; soil respiration was on average 20% lower in the litter removal and 43% higher in the litter addition treatment compared to the controls but litter addition did not change microbial biomass. We predicted a 9% increase in soil respiration in the litter addition plots, based on the 20% decrease in the litter removal plots and an 11% reduction due to lower fine root biomass in the litter addition plots. The 43% measured increase in soil respiration was therefore 34% higher than predicted and it is possible that this 'extra' CO(2) was a result of priming effects, i.e. stimulation of the decomposition of older soil organic matter by the addition of fresh organic matter. Our results show that increases in aboveground litter production as a result of global change have the potential to cause considerable losses of soil carbon to the atmosphere in tropical forests.

  9. Nitrogen transfers and air-sea N2O fluxes in the upwelling off Namibia within the oxygen minimum zone: a 3-D model approach

    NASA Astrophysics Data System (ADS)

    Gutknecht, E.; Dadou, I.; Le Vu, B.; Cambon, G.; Sudre, J.; Garçon, V.; Machu, E.; Rixen, T.; Kock, A.; Flohr, A.; Paulmier, A.; Lavik, G.

    2011-04-01

    As regions of high primary production and being often associated to Oxygen Minimum Zones (OMZs), Eastern Boundary Upwelling Systems (EBUS) represent key regions for the oceanic nitrogen (N) cycle. Indeed, by exporting the Organic Matter (OM) and nutrients produced in the coastal region to the open ocean, EBUS can play an important role in sustaining primary production in subtropical gyres. Losses of fixed inorganic N, through denitrification and anammox processes and through nitrous oxide (N2O) emissions to the atmosphere, take place in oxygen depleted environments such as EBUS, and alleviate the role of these regions as a source of N. In the present study, we developed a 3-D coupled physical/biogeochemical (ROMS/BioBUS) model for investigating the full N budget in the Namibian sub-system of the Benguela Upwelling System (BUS). The different state variables of a climatological experiment have been compared to different data sets (satellite and in situ observations) and show that the model is able to represent this biogeochemical oceanic region. The N transfer is investigated in the Namibian upwelling system using this coupled model, especially in the Walvis Bay area between 22° S and 24° S where the OMZ is well developed (O2 < 0.5 ml O2 l-1). The upwelling process advects 24.2 × 1010 mol N yr-1 of nitrate enriched waters over the first 100 m over the slope and over the continental shelf. The meridional advection by the alongshore Benguela current brings also nutrient-rich waters with 21.1 × 1010 mol N yr-1. 10.5 × 1010 mol N yr-1 of OM are exported outside of the continental shelf (between 0 and 100-m depth). 32.4% and 18.1% of this OM are exported by advection in the form of Dissolved and Particulate Organic Matters (DOM and POM), respectively, however vertical sinking of POM represents the main contributor (49.5%) to OM export outside of the first 100-m depth of the water column on the continental shelf. The continental slope also represents a net N export

  10. Catalytic mechanism of α-class carbonic anhydrases: CO2 hydration and proton transfer.

    PubMed

    Boone, Christopher D; Pinard, Melissa; McKenna, Rob; Silverman, David

    2014-01-01

    The carbonic anhydrases (CAs; EC 4.2.1.1) are a family of metalloenzymes that catalyze the reversible hydration of carbon dioxide (CO2) and dehydration of bicarbonate (HCO3 (-)) in a two-step ping-pong mechanism: [Formula: see text] CAs are ubiquitous enzymes and are categorized into five distinct classes (α, β, γ, δ and ζ). The α-class is found primarily in vertebrates (and the only class of CA in mammals), β is observed in higher plants and some prokaryotes, γ is present only in archaebacteria whereas the δ and ζ classes have only been observed in diatoms.The focus of this chapter is on α-CAs as the structure-function relationship is best understood for this class, in particular for humans. The reader is referred to other reviews for an overview of the structure and catalytic mechanism of the other CA classes. The overall catalytic site structure and geometry of α-CAs are described in the first section of this chapter followed by the kinetic studies, binding of CO2, and the proton shuttle network.

  11. Modelling the CO2 atmosphere-ocean flux in the upwelling zones using radiative transfer tools

    NASA Astrophysics Data System (ADS)

    Krapivin, Vladimir F.; Varotsos, Costas A.

    2016-12-01

    An advanced mathematical model of the radiation forcing on the ocean surface is proposed for the assessment of the CO2 fluxes between atmosphere and ocean boundary in the upwelling zones. Two types of the upwelling are considered: coastal and local in the open ocean that are closely associated with changes in solar irradiance. The proposed model takes into account the maximal number of the carbon fluxes in the upwelling ecosystem considering that in the latter the only original source of energy and matter for all forms of life is the energy of the solar radiation. The vertical structure of the upwelling zone is represented by four levels: the upper mixed layer above the thermocline, the intermediate photic layer below the thermocline, the deep ocean and the near-bottom layer. Peruvian upwelling and typical local upwelling of tropical pelagic region are considered as examples for the model calculations.

  12. High-power ultrasonic system for the enhancement of mass transfer in supercritical CO2 extraction processes.

    PubMed

    Riera, Enrique; Blanco, Alfonso; García, José; Benedito, José; Mulet, Antonio; Gallego-Juárez, Juan A; Blasco, Miguel

    2010-02-01

    Oil is an important component of almonds and other vegetable substrates that can show an influence on human health. In this work the development and validation of an innovative, robust, stable, reliable and efficient ultrasonic system at pilot scale to assist supercritical CO(2) extraction of oils from different substrates is presented. In the extraction procedure ultrasonic energy represents an efficient way of producing deep agitation enhancing mass transfer processes because of some mechanisms (radiation pressure, streaming, agitation, high amplitude vibrations, etc.). A previous work to this research pointed out the feasibility of integrating an ultrasonic field inside a supercritical extractor without losing a significant volume fraction. This pioneer method enabled to accelerate mass transfer and then, improving supercritical extraction times. To commercially develop the new procedure fulfilling industrial requirements, a new configuration device has been designed, implemented, tested and successfully validated for supercritical fluid extraction of oil from different vegetable substrates.

  13. Attempts To Catalyze the Electrochemical CO2-to-Methanol Conversion by Biomimetic 2e(-) + 2H(+) Transferring Molecules.

    PubMed

    Saveant, Jean-Michel; Tard, Cédric

    2016-01-27

    In the context of the electrochemical and photochemical conversion of CO2 to liquid fuels, one of the most important issues of contemporary energy and environmental issues, the possibility of pushing the reduction beyond the CO and formate level and catalytically generate products such as methanol is particularly attractive. Biomimetic 2e(-) + 2H(+) is often viewed as a potential hydride donor. This has been the object of a recent interesting attempt (J. Am. Chem. Soc. 2014, 136, 14007) in which 6,7-dimethyl-4-hydroxy-2-mercaptopteridine was reported as a catalyst of the electrochemical conversion of CO2 to methanol and formate, based on cyclic voltammetric, (13)C NMR, IR, and GC analyses. After checking electrolysis at the reported potential and at a more negative potential to speed up the reaction, it appears, on (1)H NMR and gas chromatographic grounds, that there is neither catalysis nor methanol and nor formate production. (1)H NMR (with H2O presaturation) brings about an unambiguous answer to the eventual production of methanol and formate, much more so than (13)C NMR, which can even be misleading when no internal standard is used as in the above-mentioned paper. IR analysis is even less conclusive. Use of a GC technique with sufficient sensitivity confirmed the lack of methanol formation. The direct or indirect hydride transfer electrochemical reduction of CO2 to formate and to methanol remains an open question. Original ideas and efforts such as those discussed here are certainly worth tempting. However, in view of the importance of the stakes, it appears necessary to carefully check reports in this area.

  14. Air-sea exchange of carbon dioxide in the Southern Ocean and Antarctic marginal ice zone

    NASA Astrophysics Data System (ADS)

    Butterworth, Brian J.; Miller, Scott D.

    2016-07-01

    Direct carbon dioxide flux measurements using eddy covariance from an icebreaker in the high-latitude Southern Ocean and Antarctic marginal ice zone are reported. Fluxes were combined with the measured water-air carbon dioxide partial pressure difference (ΔpCO2) to compute the air-sea gas transfer velocity (k, normalized to Schmidt number 660). The open water data showed a quadratic relationship between k (cm h-1) and the neutral 10 m wind speed (U10n, m s-1), kopen = 0.245 U10n2 + 1.3, in close agreement with decades old tracer-based results and much lower than cubic relationships inferred from previous open ocean eddy covariance studies. In the marginal ice zone, the effective gas transfer velocity decreased in proportion to sea ice cover, in contrast with predictions of enhanced gas exchange in the presence of sea ice. The combined open water and marginal ice zone results affect the calculated magnitude and spatial distribution of Southern Ocean carbon flux.

  15. Air-sea carbon dioxide exchange in the Southern Ocean and Antarctic Sea ice zone

    NASA Astrophysics Data System (ADS)

    Butterworth, Brian J.

    The Southern Ocean is an important part of the global carbon cycle, responsible for roughly half of the carbon dioxide (CO2) absorbed by the global ocean. The air-sea CO2 flux (Fc) can be expressed as the product of the water-air CO2 partial pressure difference (DeltapCO2) and the gas transfer velocity ( k), an exchange coefficient which represents the efficiency of gas exchange. Generally, Fc is negative (a sink) throughout the Southern Ocean and Antarctic sea ice zone (SIZ), but uncertainty in k has made it difficult to develop an accurate regional carbon budget. Constraining the functional dependence of k on wind speed in open water environments, and quantifying the effect of sea ice on k, will reduce uncertainty in the estimated contribution of the Southern Ocean and Antarctic SIZ to the global carbon cycle. To investigate Fc in the Southern Ocean, a ruggedized, unattended, closed-path eddy covariance (EC) system was deployed on the Antarctic research vessel Nathaniel B. Palmer for nine cruises during 18 months from January 2013 to June 2014 in the Southern Ocean and coastal Antarctica. The methods are described and results are shown for two cruises chosen for their latitudinal range, inclusion of open water and sea ice cover, and large DeltapCO2. The results indicated that ship-based unattended EC measurements in high latitudes are feasible, and recommendations for deployments in such environments were provided. Measurements of Fc and DeltapCO2 were used to compute k. The open water data showed a quadratic relationship between k (cm hr-1) and the neutral 10-m wind speed (U10n, m s -1), k=0.245 U10n 2+1.3, in close agreement with tracer-based results and much lower than previous EC studies. In the SIZ, it was found that k decreased in proportion to sea ice cover. This contrasted findings of enhanced Fc in the SIZ by previous open-path EC campaigns. Using the NBP results a net annual Southern Ocean (ocean south of 30°S) carbon flux of -1.1 PgC yr-1 was

  16. Changes in mass and energy transfer between the canopy and the atmosphere: model development and testing with a free-air CO2 enrichment (FACE) experiment

    NASA Astrophysics Data System (ADS)

    Manunta, Paolo; Grant, Robert F.; Feng, Yongshen; Kimball, Bruce A.; Pinter, Paul J.; La Morte, Robert L.; Hunsaker, Douglas J.; Wall, D.

    2002-02-01

    The rationale for this study is found in the probable higher temperatures and changes in rainfall patterns that are expected in the future as a result of increasing levels of CO2 in the atmosphere. In particular, higher air temperatures may cause an increase in evapotranspiration demand while a reduction in rainfall could increase the severity and duration of drought in arid and semi-arid regions. Representation of the water transfer scheme includes water uptake by roots and the interaction between evapotranspiration and CO2 enrichment. The predicted response of a spring wheat ( Triticum aestivum L. cv. Yecora rojo) canopy in terms of energy exchange processes to elevated atmospheric CO2 level was tested against measurements collected at the FACE (Free Air Enrichment Experiment) site in 1994. Simulated and measured canopy conductances were reduced by about 30% under elevated [CO2] under optimum conditions of water supply. Reductions in latent heat fluxes under elevated instead of ambient [CO2] caused reductions in both simulated and measured seasonal water use of 6% under optimum and 2% under suboptimum irrigation. The soil-plant-atmosphere water transfer scheme proposed here offers several advances in the simulation of land surface interactions. First, the stomatal resistance model minimizes assumptions in existing land surface schemes about the effects of interactions among environmental conditions (radiation, temperature, CO2) upon stomatal behavior. These interactions are resolved in the calculation of CO2 in which processes are already well understood.

  17. Assessment of the Brain's Macro- and Micro-Circulatory Blood Flow Responses to CO2 via Transfer Function Analysis

    PubMed Central

    Müller, Martin W.-D.; Österreich, Mareike; Müller, Andreas; Lygeros, John

    2016-01-01

    Objectives: At present, there is no standard bedside method for assessing cerebral autoregulation (CA) with high temporal resolution. We combined the two methods most commonly used for this purpose, transcranial Doppler sonography (TCD, macro-circulation level), and near-infrared spectroscopy (NIRS, micro-circulation level), in an attempt to identify the most promising approach. Methods: In eight healthy subjects (5 women; mean age, 38 ± 10 years), CA disturbance was achieved by adding carbon dioxide (CO2) to the breathing air. We simultaneously recorded end-tidal CO2 (ETCO2), blood pressure (BP; non-invasively at the fingertip), and cerebral blood flow velocity (CBFV) in both middle cerebral arteries using TCD and determined oxygenated and deoxygenated hemoglobin levels using NIRS. For the analysis, we used transfer function calculations in the low-frequency band (0.07–0.15 Hz) to compare BP–CBFV, BP–oxygenated hemoglobin (OxHb), BP–tissue oxygenation index (TOI), CBFV–OxHb, and CBFV–TOI. Results: ETCO2 increased from 37 ± 2 to 44 ± 3 mmHg. The CO2-induced CBFV increase significantly correlated with the OxHb increase (R2 = 0.526, p < 0.001). Compared with baseline, the mean CO2 administration phase shift (in radians) significantly increased (p < 0.005) from –0.67 ± 0.20 to –0.51 ± 0.25 in the BP–CBFV system, and decreased from 1.21 ± 0.81 to −0.05 ± 0.91 in the CBFV–OxHb system, and from 0.94 ± 1.22 to −0.24 ± 1.0 in the CBFV–TOI system; no change was observed for BP–OxHb (0.38 ± 1.17 to 0.41 ± 1.42). Gain changed significantly only in the BP–CBFV system. The correlation between the ETCO2 change and phase change was higher in the CBFV–OxHb system [r = −0.60; 95% confidence interval (CI): −0.16, −0.84; p < 0.01] than in the BP–CBFV system (r = 0.52; 95% CI: 0.03, 0.08; p < 0.05). Conclusion: The transfer function characterizes the blood flow transition from macro- to micro-circulation by time delay only. The CBFV

  18. Rotational dependence of the proton-transfer reaction HBr+ + CO2-->HOCO+ + Br. I. Energy versus angular momentum effects.

    PubMed

    Paetow, Lisa; Unger, Franziska; Beichel, Witali; Frenking, Gernot; Weitzel, Karl-Michael

    2010-05-07

    Cross sections for the endothermic proton-transfer reactions of rotationally state-selected HBr(+) and DBr(+) ions with CO(2) were measured in a guided ion beam apparatus in order to determine the influence of rotational excitation and collision energy in the center of mass (c.m.) system on the cross section. Ab initio calculations were performed to obtain energetic information about reactants, intermediates, and products. In the experiment HBr(+) and DBr(+) ions were prepared with the same mean rotational quantum number but different mean rotational energies as the rotational constants differ by about a factor of two. The mean rotational energy was varied from 1.4 to 66.3 meV for HBr(+) and from 0.7 to 43.0 meV for DBr(+). Collision energies (E(c.m.)) ranged from 0.32 to 1.00 eV. Under all conditions considered, an increase in the rotational excitation leads to a decrease in the cross section for both reactions. However, the effect is more pronounced for the higher collision energies. For E(c.m.)=1.00 and 0.85 eV; a comparison between the results for HBr(+) and DBr(+) indicates that the cross section is dominated by effects of rotational energy rather than angular momentum. For lower collision energies the cross sections for the deuteron transfer and the proton transfer are in best agreement if not compared for the same c.m. collision energy but for the same value of the difference between the collision energy and the reaction enthalpy.

  19. Hydrothermal energy transfer and contribution to autotrophic CO2 fixation down sediment core in Central Indian Basin

    NASA Astrophysics Data System (ADS)

    Das, Anindita; LokaBharathi P., A.

    2014-05-01

    Hydrothermal Energy Transfer is not only restricted to active vents sites but also to the passive ones. These passive sources could include the sub-seafloor hydrothermal fluid flux derived from distant sources like erupting vents or from deep-mantle. The contribution from such fluxes in stimulating autotrophic carbon fixation could be measurable. In this paper an attempt is made to measure the autotrophic CO2 fixation down a siliceous sediment core (Core 20, 75?30'E, 12?S) adjoining Trace of Rodrigues Triple Junction in the Central Indian Basin (CIB) with a fluid flux influence at 15-20 cms bsf (below sea-floor) which is quite distinct from the pelagic influence on the overlying 0-15 cms bsf. This work assumes that NH4+and S2- are major e-donors/reductants to fuel C-Fixation. The down-core carbon fixation varied from 0.032-0.122μmol C g-1day-1 with the larger peak at 15-20 cms bsf. This coincides with the dips in pore-water concentrations of NH4+ and S2-. Therefore the corresponding standard free energy change (ΔG?') down-core varied from -97 at 4-6 cms bsf to -375 J μmol-1 C fixed m-3 day-1 at 12-14 cms bsf in case of NH4+. In case of S2- the values varied from -42 at 4-6 cms bsf to -162 J μmol-1 m-3 day-1at 12-14 cms bsf. Integrated down-core estimate of ΔG?' is calculated to be -26.97 J μmol-1 C fixation m-2 day-1 during CO2 fixation using NH4+ and -11.7 J μmol-1 C fixation m-2 day-1 using S2-. This fluid-flow influenced layer appears physically as a brown-green transition zone in the core at a depth of 15-20 cm bsf. Interestingly similar observations have been made in >15 such cores around the present test core. These observations suggest that this spreading bed at this depth could be due to the upward fluid flow that then spreads laterally. This spread could perhaps be more than the area that the current observations permit. So the Hydrothermal Energy Transfer is equivalent to -11.70 to -26.97 J μmol-1 C fixation m-2 day-1and corresponds to 88 μmol of

  20. Intramolecular vibrational energy redistribution and intermolecular energy transfer of benzene in supercritical CO 2: measurements from the gas phase up to liquid densities

    NASA Astrophysics Data System (ADS)

    von Benten, R.; Charvat, A.; Link, O.; Abel, B.; Schwarzer, D.

    2004-03-01

    Femtosecond pump probe spectroscopy was employed to measure intramolecular vibrational energy redistribution (IVR) and intermolecular vibrational energy transfer (VET) of benzene in the gas phase and in supercritical (sc) CO 2. We observe two IVR time scales the faster of which proceeds within τ IVR(1)<0.5 ps. The slower IVR component has a time constant of τ IVR(2)=(48±5) ps in the gas phase and in scCO 2 is accelerated by interactions with the solvent. At the highest CO 2 density it is reduced to τ IVR(2)=(6±1) ps. The corresponding IVR rate constants show a similar density dependence as the VET rate constants. Model calculations suggest that both quantities correlate with the local CO 2 density in the immediate surrounding of the benzene molecule.

  1. Using a laser-based CO2 carbon isotope analyser to investigate gas transfer in geological media

    NASA Astrophysics Data System (ADS)

    Guillon, S.; Pili, E.; Agrinier, P.

    2012-05-01

    CO2 stable carbon isotopes are very attractive in environmental research to investigate both natural and anthropogenic carbon sources. Laser-based CO2 carbon isotope analysis provides continuous measurement at high temporal resolution and is a promising alternative to isotope ratio mass spectrometry (IRMS). We performed a thorough assessment of a commercially available CO2 Carbon Isotope Analyser (CCIA DLT-100, Los Gatos Research) that allows in situ measurement of δ 13C in CO2. Using a set of reference gases of known CO2 concentration and carbon isotopic composition, we evaluated the precision, long-term stability, temperature sensitivity and concentration dependence of the analyser. Despite good precision calculated from Allan variance (5.0 ppm for CO2 concentration, and 0.05 ‰ for δ 13C at 60 s averaging), real performances are altered by two main sources of error: temperature sensitivity and dependence of δ 13C on CO2 concentration. Data processing is required to correct for these errors. Following application of these corrections, we achieve an accuracy of 8.7 ppm for CO2 concentration and 1.3 ‰ for δ 13C, which is worse compared to mass spectrometry performance, but still allowing field applications. With this portable analyser we measured CO2 flux degassed from rock in an underground tunnel. The obtained carbon isotopic composition agrees with IRMS measurement, and can be used to identify the carbon source.

  2. Measurements of momentum transfer coefficients for H2, N2, CO and CO2 incident upon spacecraft surfaces

    NASA Technical Reports Server (NTRS)

    Cook, S. R.; Hoffbauer, M. A.

    1997-01-01

    Measurements of momentum transfer coefficients were made for gas-surface interactions between the Space Shuttle reaction control jet plume gases and the solar panel array materials to be used on the International Space Station. Actual conditions were simulated using a supersonic nozzle source to produce beams of the gases with approximately the same average velocities as the gases have in the Shuttle plumes. Samples of the actual solar panel materials were mounted on a torsion balance that was used to measure the force exerted on the surfaces by the molecular beams. Measurements were made with H2, N2, CO, and CO2 incident upon the solar array material, Kapton, SiO2-coated Kapton, and Z93-coated Al. The measurements showed that molecules scatter from the surfaces more specularly as the angle of incidence increases and that scattering behavior has a strong dependence upon both the incident gas and velocity. These results show that for some technical surfaces the simple assumption of diffuse scattering with complete thermal accommodation is entirely inadequate. It is clear that additional measurements are required to produce models that more accurately describe the gas-surface interactions encountered in rarefied flow regimes.

  3. Measurement of Momentum Transfer Coefficients for H2, N2, CO, and CO2 Incident Upon Spacecraft Surfaces

    NASA Technical Reports Server (NTRS)

    Cook, Steven R.; Hoffbauer, Mark A.

    1997-01-01

    Measurements of momentum transfer coefficients were made for gas-surface interactions between the Space Shuttle reaction control jet plume gases and the solar panel array materials to be used on the International Space Station. Actual conditions were simulated using a supersonic nozzle source to produce beams of the gases with approximately the same average velocities as the gases have in the Shuttle plumes. Samples of the actual solar panel materials were mounted on a torsion balance that was used to measure the force exerted on the surfaces by the molecular beams. Measurements were made with H2, N2, CO, and CO2 incident upon the solar array material, Kapton, SiO2-coated Kapton, and Z93-coated Al. The measurements showed that molecules scatter from the surfaces more specularly as the angle of incidence increases and that the scattering behavior has a strong dependence upon both the incident gas and velocity. These results show that for some technical surfaces the simple assumption of diffuse scattering with complete thermal accommodation is entirely inadequate. It is clear that additional measurements are required to produce models that more accurately describe the gas-surface interactions encountered in rarefied flow regimes.

  4. Two-center interference effects in (e, 2e) ionization of H2 and CO2 at large momentum transfer

    NASA Astrophysics Data System (ADS)

    Yamazaki, Masakazu; Nakajima, Isao; Satoh, Hironori; Watanabe, Noboru; Jones, Darryl; Takahashi, Masahiko

    2015-09-01

    In recent years, there has been considerable interest in understanding quantum mechanical interference effects in molecular ionization. Since this interference appears as a consequence of coherent electron emission from the different molecular centers, it should depend strongly on the nature of the ionized molecular orbital. Such molecular orbital patterns can be investigated by means of binary (e, 2e) spectroscopy, which is a kinematically-complete electron-impact ionization experiment performed under the high-energy Bethe ridge conditions. In this study, two-center interference effects in the (e, 2e) cross sections of H2 and CO2 at large momentum transfer are demonstrated with a high-statistics experiment, in order to elucidate the relationship between molecular orbital patterns and the interference structure. It is shown that the two-center interference is highly sensitive to the phase, spatial pattern, symmetry of constituent atomic orbital, and chemical bonding nature of the molecular orbital. This work was partially supported by Grant-in-Aids for Scientific Research (S) (No. 20225001) and for Young Scientists (B) (No. 21750005) from the Ministry of Education, Culture, Sports, Science and Technology.

  5. Air-ice CO2 fluxes and pCO2 dynamics in the Arctic coastal area (Amundsen Gulf, Canada)

    NASA Astrophysics Data System (ADS)

    Geilfus, Nicolas-Xavier; Tison, Jean Louis; Carnat, Gauthier; Else, Brent; Borges, Alberto V.; Thomas, Helmuth; Shadwick, Elizabeth; Delille, Bruno

    2010-05-01

    Sea ice covers about 7% of the Earth surface at its maximum seasonal extent. For decades sea ice was assumed to be an impermeable and inert barrier for air - sea exchange of CO2 so that global climate models do not include CO2 exchange between the oceans and the atmosphere in the polar regions. However, uptake of atmospheric CO2 by sea ice cover was recently reported raising the need to further investigate pCO2 dynamics in the marine cryosphere realm and related air-ice CO2 fluxes. In addition, budget of CO2 fluxes are poorly constrained in high latitudes continental shelves [Borges et al., 2006]. We report measurements of air-ice CO2 fluxes above the Canadian continental shelf and compare them to previous measurements carried out in Antarctica. We carried out measurements of pCO2 within brines and bulk ice, and related air-ice CO2 fluxes (chamber method) in Antarctic first year pack ice ("Sea Ice Mass Balance in Antarctica -SIMBA" drifting station experiment September - October 2007) and in Arctic first year land fast ice ("Circumpolar Flaw Lead" - CFL, April - June 2008). These 2 experiments were carried out in contrasted sites. SIMBA was carried out on sea ice in early spring while CFL was carried out in from the middle of the winter to the late spring while sea ice was melting. Both in Arctic and Antarctic, no air-ice CO2 fluxes were detected when sea ice interface was below -10°C. Slightly above -10°C, fluxes toward the atmosphere were observed. In contrast, at -7°C fluxes from the atmosphere to the ice were significant. The pCO2 of the brine exhibits a same trend in both hemispheres with a strong decrease of the pCO2 anti-correlated with the increase of sea ice temperature. The pCO2 shifted from a large over-saturation at low temperature to a marked under-saturation at high temperature. These air-ice CO2 fluxes are partly controlled by the permeability of the air-ice interface, which depends of the temperature of this one. Moreover, air-ice CO2 fluxes are

  6. Multicomponent CO2-Brine Simulations of Fluid and Heat Transfer in Sedimentary-Basin Geothermal Systems: Expanding Geothermal Energy Opportunities

    NASA Astrophysics Data System (ADS)

    Saar, M. O.; Randolph, J. B.

    2011-12-01

    In a carbon dioxide plume geothermal (CPG) system, carbon dioxide (CO2) is pumped into existing high-permeability geologic formations that are overlain by a low-permeability caprock. The resulting CO2 plume largely displaces native formation fluid and is heated by the natural in-situ heat and background geothermal heat flux. A portion of the heated CO2 is piped to the surface to produce power and/or to provide heat for direct use before being returned to the geologic reservoir. Non-recoverable CO2 in the subsurface is geologically sequestered, serving as a CO2 sink. As such, this approach results in a geothermal power plant with a negative carbon footprint. We present results of calculations concerning geothermal power plant efficiencies and energy production rates in both traditional reservoir-based systems and engineered geothermal systems (EGS) when CO2, rather than water, is used as the subsurface working fluid. While our previous studies have examined geologic systems with established CO2 plumes, we focus here on multicomponent (CO2 + brine) systems. Numerical simulations (e.g., Randolph and Saar, Geophysical Research Letters, 2011) indicate that CPG systems provide several times the heat energy recovery of similar water-based systems. Furthermore, the CPG method results in higher geothermal heat extraction efficiencies than both water- and CO2-based EGS. Therefore, CPG should further extend the applicability of geothermal energy utilization to regions with subsurface temperatures and heat flow rates that are even lower than those that may be added due to switching from water- to CO2-based EGS. Finally, simulations at present suggest that multicomponent effects - e.g., buoyant flow as CO2 rises over denser brine - may enhance heat extraction in CPG systems compared to traditional water-based geothermal approaches.

  7. Air-Sea Interactions in CLIMODE: In-Situ Observations

    NASA Astrophysics Data System (ADS)

    Bigorre, S.; Weller, R.

    2006-12-01

    The subtropical mode water of the North Atlantic or Eighteen Degree Water (EDW) is an important component of the oceanic circulation. Its formation and evolution are linked to fundamental aspects of the oceanic climate. A central formation process involves the subduction of surface water through air-sea interactions. Conditions for this are ideal in the Gulf Stream region when warm water interacts with cold air above, sinks and is trapped in the late winter, thereby ventilating the interior. The study program CLIvar MOde Water Dynamic Experiment (CLIMODE), sponsored by NSF, is designed to quantify and understand which processes lead to the formation and dissipation of EDW. A key component to this goal is the knowledge of buoyancy fluxes in the region of EDW formation. The Upper Ocean Processes (UOP) group deployed a 3-m discus buoy anchored in the Gulf Stream (64W, 38N) in November 2005. Oceanographic instruments collect data along the mooring line while meteorological and surface sensors are placed on the buoy and collect data every minute. Since the deployment, hourly averages of the meteorological data were transmitted through the Argos satellite system. These data were plugged in the TOGA-COARE bulk algorithm to estimate air-sea fluxes. These preliminary results are presented, while the full dataset will be analyzed after recovery of the buoy in November 2006. Heat fluxes estimates indicate high heat loss events. In December 2005, regular losses larger than 1000W/m2 occurred. These heat loss events are associated with cold air outbreaks. When the air-sea temperature gradient increases, winds also tend to increase indicating a destabilization of the boundary layer and production of turbulence, enhancing further the heat transfer. As the air-sea temperature gradient decreases in the late winter, heat loss also decreases. The SST signal is seen to modulate the heat fluxes on lower frequencies than air temperature changes. This kind of signal tends therefore to be

  8. Combining Experiments and Simulation of Gas Absorption for Teaching Mass Transfer Fundamentals: Removing CO2 from Air Using Water and NaOH

    ERIC Educational Resources Information Center

    Clark, William M.; Jackson, Yaminah Z.; Morin, Michael T.; Ferraro, Giacomo P.

    2011-01-01

    Laboratory experiments and computer models for studying the mass transfer process of removing CO2 from air using water or dilute NaOH solution as absorbent are presented. Models tie experiment to theory and give a visual representation of concentration profiles and also illustrate the two-film theory and the relative importance of various…

  9. Snowflake Impact on the Air-Sea Interface

    NASA Astrophysics Data System (ADS)

    Murphy, David

    2016-11-01

    The air-sea interface is the site of globally important exchanges of mass, momentum, and heat between the sea and atmosphere. These climate-driving exchanges occur through small-scale processes such as bubble entrainment and bursting, raindrop impact, and wind-wave creation. The physics of snowflakes falling on the sea surface has not been previously considered. High speed imaging of natural snowflakes of characteristic size up to 6.5 mm falling at a mean speed of 1 m/s into an aquarium of chilled seawater reveals a complex multiphase flow. Snowflakes impacting and crossing the air-seawater interface appear to entrain a thin air film which forms micro-bubbles as the snowflake melts. Large, morphologically complex snowflakes may entrain hundreds of micro-bubbles which are up to 0.15 mm in diameter. Large snowflakes melt milliseconds after entry and subsequently form a downward-moving vortex ring of freshwater, evident from the motion of the bubbles it contains, which may penetrate up to 16 mm below the surface. Buoyant freshwater and bubbles then rise, with larger bubbles escaping from the downward flow more quickly than the smaller bubbles. The dissolution and popping of these bubbles represent previously unrecognized sources of air-sea gas transfer and marine aerosol droplet creation, respectively.

  10. Energy transfer upon collision of selectively excited CO2 molecules: State-to-state cross sections and probabilities for modeling of atmospheres and gaseous flows

    NASA Astrophysics Data System (ADS)

    Lombardi, A.; Faginas-Lago, N.; Pacifici, L.; Grossi, G.

    2015-07-01

    Carbon dioxide molecules can store and release tens of kcal/mol upon collisions, and such an energy transfer strongly influences the energy disposal and the chemical processes in gases under the extreme conditions typical of plasmas and hypersonic flows. Moreover, the energy transfer involving CO2 characterizes the global dynamics of the Earth-atmosphere system and the energy balance of other planetary atmospheres. Contemporary developments in kinetic modeling of gaseous mixtures are connected to progress in the description of the energy transfer, and, in particular, the attempts to include non-equilibrium effects require to consider state-specific energy exchanges. A systematic study of the state-to-state vibrational energy transfer in CO2 + CO2 collisions is the focus of the present work, aided by a theoretical and computational tool based on quasiclassical trajectory simulations and an accurate full-dimension model of the intermolecular interactions. In this model, the accuracy of the description of the intermolecular forces (that determine the probability of energy transfer in molecular collisions) is enhanced by explicit account of the specific effects of the distortion of the CO2 structure due to vibrations. Results show that these effects are important for the energy transfer probabilities. Moreover, the role of rotational and vibrational degrees of freedom is found to be dominant in the energy exchange, while the average contribution of translations, under the temperature and energy conditions considered, is negligible. Remarkable is the fact that the intramolecular energy transfer only involves stretching and bending, unless one of the colliding molecules has an initial symmetric stretching quantum number greater than a threshold value estimated to be equal to 7.

  11. Energy transfer upon collision of selectively excited CO2 molecules: State-to-state cross sections and probabilities for modeling of atmospheres and gaseous flows.

    PubMed

    Lombardi, A; Faginas-Lago, N; Pacifici, L; Grossi, G

    2015-07-21

    Carbon dioxide molecules can store and release tens of kcal/mol upon collisions, and such an energy transfer strongly influences the energy disposal and the chemical processes in gases under the extreme conditions typical of plasmas and hypersonic flows. Moreover, the energy transfer involving CO2 characterizes the global dynamics of the Earth-atmosphere system and the energy balance of other planetary atmospheres. Contemporary developments in kinetic modeling of gaseous mixtures are connected to progress in the description of the energy transfer, and, in particular, the attempts to include non-equilibrium effects require to consider state-specific energy exchanges. A systematic study of the state-to-state vibrational energy transfer in CO2 + CO2 collisions is the focus of the present work, aided by a theoretical and computational tool based on quasiclassical trajectory simulations and an accurate full-dimension model of the intermolecular interactions. In this model, the accuracy of the description of the intermolecular forces (that determine the probability of energy transfer in molecular collisions) is enhanced by explicit account of the specific effects of the distortion of the CO2 structure due to vibrations. Results show that these effects are important for the energy transfer probabilities. Moreover, the role of rotational and vibrational degrees of freedom is found to be dominant in the energy exchange, while the average contribution of translations, under the temperature and energy conditions considered, is negligible. Remarkable is the fact that the intramolecular energy transfer only involves stretching and bending, unless one of the colliding molecules has an initial symmetric stretching quantum number greater than a threshold value estimated to be equal to 7.

  12. Three-Dimensional Modeling of Air-Sea Interaction

    NASA Astrophysics Data System (ADS)

    Regis, J. L.; Slinn, D. N.

    2004-12-01

    Deep-water wave breaking is crucial in the transfer of heat, gases, and momentum between the ocean and the atmosphere. Observations of these events have provided qualitative support to this end, and yet accurate quantification of momentum transfer for strong winds and nonlinear waves has remained a challenge. In recent years, advances have been made in the development of numerous algorithms to capture and describe air-sea interaction. Most, however, are idealized and only capable of modeling fluid flow within the two-dimensional approximation. Thus, many important characteristics of the flow composition and breaking process are ignored, oversimplified, or remain unknown. We employ a three-dimensional, time-dependent, finite difference, volume of fluid model, including both the flow of air and water, entitled TRUCHAS, to address the issue of deep-water breaking waves. Our model utilizes the multidimensional piecewise linear interface calculation method to assess the volume fraction of each fluid material in every mesh cell. The model solves conservation equations for mass and momentum for multiple fluids within the domain and tracks the interfaces between them. A great many details of the flow development are available for analysis from the model output. These include wind and water velocities, pressure gradients in both the air and sea around a breaking wave, the development and evolution of wind-generated waves, and the corresponding transfer of momentum from the atmosphere to the ocean. Our results are correlated with laboratory experiments conducted at the University of Miami's Air-Sea Interaction Salt-water Tank that possesses both wind and wave generating capabilities. Preliminary model results show good qualitative agreement to laboratory data.

  13. Tropical Cyclone Induced Air-Sea Interactions Over Oceanic Fronts

    NASA Astrophysics Data System (ADS)

    Shay, L. K.

    2012-12-01

    Recent severe tropical cyclones underscore the inherent importance of warm background ocean fronts and their interactions with the atmospheric boundary layer. Central to the question of heat and moisture fluxes, the amount of heat available to the tropical cyclone is predicated by the initial mixed layer depth and strength of the stratification that essentially set the level of entrainment mixing at the base of the mixed layer. In oceanic regimes where the ocean mixed layers are thin, shear-induced mixing tends to cool the upper ocean to form cold wakes which reduces the air-sea fluxes. This is an example of negative feedback. By contrast, in regimes where the ocean mixed layers are deep (usually along the western part of the gyres), warm water advection by the nearly steady currents reduces the levels of turbulent mixing by shear instabilities. As these strong near-inertial shears are arrested, more heat and moisture transfers are available through the enthalpy fluxes (typically 1 to 1.5 kW m-2) into the hurricane boundary layer. When tropical cyclones move into favorable or neutral atmospheric conditions, tropical cyclones have a tendency to rapidly intensify as observed over the Gulf of Mexico during Isidore and Lili in 2002, Katrina, Rita and Wilma in 2005, Dean and Felix in 2007 in the Caribbean Sea, and Earl in 2010 just north of the Caribbean Islands. To predict these tropical cyclone deepening (as well as weakening) cycles, coupled models must have ocean models with realistic ocean conditions and accurate air-sea and vertical mixing parameterizations. Thus, to constrain these models, having complete 3-D ocean profiles juxtaposed with atmospheric profiler measurements prior, during and subsequent to passage is an absolute necessity framed within regional scale satellite derived fields.

  14. Off-On-Off fluorescence behavior of an intramolecular charge transfer probe toward anions and CO2

    NASA Astrophysics Data System (ADS)

    Ali, Rashid; Razi, Syed S.; Shahid, Mohammad; Srivastava, Priyanka; Misra, Arvind

    2016-11-01

    The photophysical behavior of a newly developed fluorescent probe, tricyanoethylphenyl phenanthroimidazole (TCPPI) has been studied. Upon interaction of different class of anions TCPPI displayed naked-eye sensitive fluorescence "turn-on" response to detect selectively F- (0.98 μM, 18.62 ppb) and CN- (1.12 μM, 29.12 ppb) anions in acetonitrile (MeCN). Job's plot analysis revealed a 1:1 binding stoichiometry between probe and anions. The spectral data analysis and 1H NMR titration studies suggested about the affinity of F- and CN- anions with moderately acidic - NH fragment of imidazolyl unit of probe through deprotonation and H-bonding interaction. Moreover, the anion activated probe upon interaction with CO2 revived photophysical properties of probe, "On-Off-On" type fluorescence and enabled anion-induced CO2 sensing in the medium.

  15. Parity-dependent rotational energy transfer in CN(A(2)Π, ν = 4, j F(1)ε) + N2, O2, and CO2 collisions.

    PubMed

    McGurk, Stephen J; Halpern, Joshua B; McKendrick, Kenneth G; Costen, Matthew L

    2014-03-20

    We report state-resolved total removal cross sections and state-to-state rotational energy transfer (RET) cross sections for collisions of CN(A(2)Π, ν = 4, j F1ε) with N2, O2, and CO2. CN(X(2)Σ(+)) was produced by 266 nm photolysis of ICN in a thermal bath (296 K) of the collider gas. A circularly polarized pulse from a dye laser prepared CN(A(2)Π, ν = 4) in a range of F1e rotational states, j = 2.5, 3.5, 6.5, 11.5, 13.5, and 18.5. These prepared states were monitored using the circularly polarized output of an external cavity diode laser by frequency-modulated (FM) spectroscopy on the CN(A-X)(4,2) band. The FM Doppler profiles were analyzed as a function of pump-probe delay to determine the time dependence of the population of the initially prepared states. Kinetic analysis of the resulting time dependences was used to determine total removal cross sections from the initially prepared levels. In addition, a range of j' F1e and j' F2f product states resulting from rotational energy transfer out of the j = 6.5 F1e initial state were probed, from which state-to-state RET cross sections were measured. The total removal cross sections lie in the order CO2 > N2 > O2, with evidence for substantial cross sections for electronic and/or reactive quenching of CN(A, ν = 4) to unobserved products with CO2 and O2. This is supported by the magnitude of the state-to-state RET cross sections, where a deficit of transferred population is apparent for CO2 and O2. A strong propensity for conservation of rotational parity in RET is observed for all three colliders. Spin-orbit-changing cross sections are approximately half of those of the respective conserving cross sections. These results are in marked disagreement with previous experimental observations with N2 as a collider but are in good agreement with quantum scattering calculations from the same study ( Khachatrian et al. J. Phys. Chem. A 2009 , 113 , 3922 ). Our results with CO2 as a collider are similarly in strong

  16. Mass transfers induced by flow of CO2 rich-brine through fractured cement: experiment and modeling

    NASA Astrophysics Data System (ADS)

    Habdoulghafour, H.; Luquot, L.; Gouze, P.

    2011-12-01

    Long-term confinement failure is a key issue in the assessment of the confidence levels of CO2 storage. Evaluating the potential for CO2 leakage through wells (casing, cements and interfaces with the cap-rock) is of primary importance for the analysis of latent and short-range risks of confinement failure. Some controversy remains regarding the risk of conventional cements. While some researchers argue that they may fail, EOR oil industry experience suggests the opposite. The issue is non-trivial. Experimental investigations on cement alteration mechanism triggered by CO2-rich brine show that both carbonation and de-carbonation mechanisms may occur and are the dominant mass exchange processes. It is tempting to conclude from the results of batch experiments that cement carbonation tends to decrease porosity and permeability, whereas de-carbonation increases both, but these assumptions must be tested using realistic flow-through experiments. Here we investigated the effect of CO2 rich-brine flowing through fractured portlandite-rich cement plugs. Experiments were carried out under realistic in situ conditions (T=80°C and P=10 MPa). Monitoring the fluid composition at the outlet allows us to measure the rate at which portlandite and CSH are dissolved and Ca-carbonate (calcite) precipitated. The precipitation of carbonate limits the fluid access to the inner part of cement (by diffusion) but, in the condition of forced flow-through CO2-rich brine in the fracture, this carbonate layer is subsequently dissolved as showed by the X-ray micro tomography performed post-mortem. Despite these coupled dissolution-precipitation mechanisms (and the on-going reaction front displacement), the permeability of the fracture remains almost constant during the experiment because the effective aperture controlled by the undissolved fraction of the cement (i.e. silica-rich minerals) is preserved. For the studied conditions, it can be concluded that the flow properties of the fractured

  17. Carbon transfer, partitioning and residence time in the plant-soil system: a comparison of two 13C-CO2 labelling techniques

    NASA Astrophysics Data System (ADS)

    Studer, Mirjam S.; Siegwolf, Rolf T. W.; Schmidt, Michael W. I.; Abiven, Samuel

    2014-05-01

    13C-CO2 labelling is a powerful tool to study the carbon (C) dynamics in plant-soil systems, whereby various approaches have been applied, differing in the duration of label exposure, the applied label strength and the sampling intervals. We made a direct comparison of the two main 13C-CO2 labelling techniques - pulse and continuous labelling - and evaluated if different approaches yield the same results regarding the C transfer time, C partitioning and the C residence time in different plant-soil compartments. We conducted a pulse labelling (exposure to 99 atom% 13C-CO2 for three hours, traced for eight days) and a continuous labelling (exposure to 10 atom% 13C-CO2, traced for 14 days) on identical plant-soil systems (Populus deltoides x nigra, Cambisol soil) and under controlled environmental conditions. The plant-soil systems were destructively harvested at five sampling dates, and the soil CO2 efflux was sampled throughout the experiments. The 13C distribution into leaves, petioles, stems, cuttings, roots, soil, microbial biomass and soil respiration was analysed and wee applied exponential (pulse labelling) and logistic (continuous labelling) functions to model the C dynamics. Our results confirm that pulse labelling is best suited to assess the minimum C transfer time, while continuous labelling can be applied to assess the C transfer through a compartment, including short-term storage pools. Both experiments yielded the same C partitioning patterns at the specific sampling days, however, the time of sampling was crucial. For example the results of belowground C partitioning were consistent only after eight days of labelling. The C mean residence times estimated by the rate constant of the exponential and logistic function were largely different for the two techniques, mostly due to the strong model assumptions (e.g. steady state). Pulse and continuous labelling techniques are both well suited to assess C cycling. With pulse labelling, the dynamics of fresh

  18. Carbon transfer, partitioning and residence time in the plant-soil system: a comparison of two 13CO2 labelling techniques

    NASA Astrophysics Data System (ADS)

    Studer, M. S.; Siegwolf, R. T. W.; Abiven, S.

    2014-03-01

    Various 13CO2 labelling approaches exist to trace carbon (C) dynamics in plant-soil systems. However, it is not clear if the different approaches yield the same results. Moreover, there is no consistent way of data analysis to date. In this study we compare with the same experimental setup the two main techniques: pulse and continuous labelling. We evaluate how these techniques perform to estimate the C transfer time, the C partitioning along time and the C residence time in different plant-soil compartments. We used identical plant-soil systems (Populus deltoides × nigra, Cambisol soil) to compare the pulse labelling approach (exposure to 99 atom % 13CO2 for three hours, traced for eight days) with a continuous labelling (exposure to 10 atom % 13CO2, traced for 14 days). The experiments were conducted in climate chambers under controlled environmental conditions. Before label addition and at four successive sampling dates, the plant-soil systems were destructively harvested, separated into leaves, petioles, stems, cuttings, roots and soil and soil microbial biomass was extracted. The soil CO2 efflux was sampled throughout the experiment. To model the C dynamics we used an exponential function to describe the 13C signal decline after pulse labelling. For the evaluation of the 13C distribution during the continuous labelling we applied a logistic function. Pulse labelling is best suited to assess the minimum C transfer time from the leaves to other compartments, while continuous labelling can be used to estimate the mean transfer time through a compartment, including short-term storage pools. The C partitioning between the plant-soil compartments obtained was similar for both techniques, but the time of sampling had a large effect: shortly after labelling the allocation into leaves was overestimated and the soil 13CO2 efflux underestimated. The results of belowground C partitioning were consistent for the two techniques only after eight days of labelling, when the

  19. Carbon transfer, partitioning and residence time in the plant-soil system: a comparison of two 13CO2 labelling techniques

    NASA Astrophysics Data System (ADS)

    Studer, M. S.; Siegwolf, R. T. W.; Abiven, S.

    2013-10-01

    Various 13CO2 labelling approaches exist to trace carbon (C) dynamics in plant-soil systems. However, it is not clear if the different approaches yield the same results. Moreover, there is no consistent way of data analysis to date. In this study we compare with the same experimental setup the two main techniques: the pulse and the continuous labelling. We evaluate how these techniques perform to estimate the C transfer velocity, the C partitioning along time and the C residence time in different plant-soil compartments. We used identical plant-soil systems (Populus deltoides x nigra, Cambisol soil) to compare the pulse labelling approach (exposure to 99 atom% 13CO2 for three hours, traced for eight days) with a continuous labelling (exposure to 10 atom% 13CO2, traced for 14 days). The experiments were conducted in climate chambers under controlled environmental conditions. Before label addition and at four successive sampling dates, the plant-soil systems were destructively harvested, separated into leaves, petioles, stems, cuttings, roots and soil and the microbial biomass was extracted from the soil. The soil CO2 efflux was sampled throughout the experiment. To model the C dynamics we used an exponential function to describe the 13C signal decline after pulse labelling. For the evaluation of the 13C distribution during the continuous labelling we suggest to use a logistic function. Pulse labelling is best suited to assess the maximum C transfer velocity from the leaves to other compartments. With continuous labelling, the mean transfer velocity through a compartment, including short-term storage pools, can be observed. The C partitioning between the plant-soil compartments was similar for both techniques, but the time of sampling had a large effect: shortly after labelling the allocation into leaves was overestimated and the soil 13CO2 efflux underestimated. The results of belowground C partitioning were consistent for the two techniques only after eight days of

  20. Sensitivity of Global Sea-Air CO2 Flux to Gas Transfer Algorithms, Climatological Wind Speeds, and Variability of Sea Surface Temperature and Salinity

    NASA Technical Reports Server (NTRS)

    McClain, Charles R.; Signorini, Sergio

    2002-01-01

    Sensitivity analyses of sea-air CO2 flux to gas transfer algorithms, climatological wind speeds, sea surface temperatures (SST) and salinity (SSS) were conducted for the global oceans and selected regional domains. Large uncertainties in the global sea-air flux estimates are identified due to different gas transfer algorithms, global climatological wind speeds, and seasonal SST and SSS data. The global sea-air flux ranges from -0.57 to -2.27 Gt/yr, depending on the combination of gas transfer algorithms and global climatological wind speeds used. Different combinations of SST and SSS global fields resulted in changes as large as 35% on the oceans global sea-air flux. An error as small as plus or minus 0.2 in SSS translates into a plus or minus 43% deviation on the mean global CO2 flux. This result emphasizes the need for highly accurate satellite SSS observations for the development of remote sensing sea-air flux algorithms.

  1. Air-sea coupling in the Hawaiian Archipelago

    NASA Astrophysics Data System (ADS)

    Souza, J. M.; Powell, B.; Mattheus, D.

    2014-12-01

    A coupled numerical model is used to investigate the ocean-atmosphere interaction in the lee of the Hawaiian archipelago. The wind curl generated by the island blocking of the trade winds is known to give rise to ocean eddies; however, the impact of the sea surface temperature (SST) and velocity fronts associated with these eddies on the atmosphere is less understood. The main coupling mechanisms are: (i) changes in the near-surface stability and surface stress, (ii) vertical transfer of momentum from higher atmospheric levels to the ocean surface due to an increase of the turbulence in the boundary layer, (iii) secondary circulations associated with perturbations in the surface atmospheric pressure over the SST fronts, and (iv) the impact of the oceanic eddy currents on the net momentum transferred between the atmosphere and the ocean. To assess the relative contribution from each process, a coupled simulation between the Regional Ocean Modeling System (ROMS) and the Weather Research and Forecasting (WRF) models is conducted for the main Hawaiian Islands. The impact of the coupling, the perturbation of the mean wind pattern, and the different spatial scales involved in the air-sea exchanges of momentum and heat are explored.

  2. Joint Air Sea Interaction (JASIN) experiment, Northwest coast of Scotland

    NASA Technical Reports Server (NTRS)

    Businger, J. A.

    1981-01-01

    The joint air sea interaction (JASIN) experiment took place off the Northwest coast of Scotland. Sea surface and boundary layer parameters were measured. The JASIN data was used as ground truth for various sensors on the SEASAT satellite.

  3. Regulation of CO2 Air Sea Fluxes by Sediments in the North Sea

    NASA Astrophysics Data System (ADS)

    Burt, William; Thomas, Helmuth; Hagens, Mathilde; Brenner, Heiko; Pätsch, Johannes; Clargo, Nicola; Salt, Lesley

    2016-04-01

    A multi-tracer approach is applied to assess the impact of boundary fluxes (e.g. benthic input from sediments or lateral inputs from the coastline) on the acid-base buffering capacity, and overall biogeochemistry, of the North Sea. Analyses of both basin-wide observations in the North Sea and transects through tidal basins at the North-Frisian coastline, reveal that surface distributions of the δ13C signature of dissolved inorganic carbon (DIC) are predominantly controlled by a balance between biological production and respiration. In particular, variability in metabolic DIC throughout stations in the well-mixed southern North Sea indicates the presence of an external carbon source, which is traced to the European continental coastline using naturally-occurring radium isotopes (224Ra and 228Ra). 228Ra is also shown to be a highly effective tracer of North Sea total alkalinity (AT) compared to the more conventional use of salinity. Coastal inputs of metabolic DIC and AT are calculated on a basin-wide scale, and ratios of these inputs suggest denitrification as a primary metabolic pathway for their formation. The AT input paralleling the metabolic DIC release prevents a significant decline in pH as compared to aerobic (i.e. unbuffered) release of metabolic DIC. Finally, long-term pH trends mimic those of riverine nitrate loading, highlighting the importance of coastal AT production via denitrification in regulating pH in the southern North Sea.

  4. In situ assessment of the velocity of carbon transfer by tracing 13 C in trunk CO2 efflux after pulse labelling: variations among tree species and seasons.

    PubMed

    Dannoura, Masako; Maillard, Pascale; Fresneau, Chantal; Plain, Caroline; Berveiller, Daniel; Gerant, Dominique; Chipeaux, Christophe; Bosc, Alexandre; Ngao, Jérôme; Damesin, Claire; Loustau, Denis; Epron, Daniel

    2011-04-01

    Phloem is the main pathway for transferring photosynthates belowground. In situ(13) C pulse labelling of trees 8-10 m tall was conducted in the field on 10 beech (Fagus sylvatica) trees, six sessile oak (Quercus petraea) trees and 10 maritime pine (Pinus pinaster) trees throughout the growing season. Respired (13) CO2 from trunks was tracked at different heights using tunable diode laser absorption spectrometry to determine time lags and the velocity of carbon transfer (V). The isotope composition of phloem extracts was measured on several occasions after labelling and used to estimate the rate constant of phloem sap outflux (kP ). Pulse labelling together with high-frequency measurement of the isotope composition of trunk CO2 efflux is a promising tool for studying phloem transport in the field. Seasonal variability in V was predicted in pine and oak by bivariate linear regressions with air temperature and soil water content. V differed among the three species consistently with known differences in phloem anatomy between broadleaf and coniferous trees. V increased with tree diameter in oak and beech, reflecting a nonlinear increase in volumetric flow with increasing bark cross-sectional area, which suggests changes in allocation pattern with tree diameter in broadleaf species. Discrepancies between V and kP indicate vertical changes in functional phloem properties.

  5. Developments in Airborne Oceanography and Air-Sea Interaction

    NASA Astrophysics Data System (ADS)

    Melville, W. K.

    2014-12-01

    , just as aircraft carriers "project force". Now we can measure winds, waves, temperatures, currents, radiative transfer, images and air-sea fluxes from aircraft over the ocean.I will review some of the history of airborne oceanography and present examples of how it can extend our knowledge and understanding of air-sea interaction.

  6. Bioelectrochemical reduction of CO(2) to CH(4) via direct and indirect extracellular electron transfer by a hydrogenophilic methanogenic culture.

    PubMed

    Villano, Marianna; Aulenta, Federico; Ciucci, Costanza; Ferri, Tommaso; Giuliano, Antonio; Majone, Mauro

    2010-05-01

    This study describes the performance of a microbial biocathode, based on a hydrogenophilic methanogenic culture, capable of reducing carbon dioxide to methane, at high rates (up to 0.055 + or - 0.002 mmol d(-1) mgVSS(-1)) and electron capture efficiencies (over 80%). Methane was produced, at potentials more negative than -650 mV vs. SHE, both via abiotically produced hydrogen gas (i.e., via hydrogenophilic methanogenesis) and via direct extracellular electron transfer. The relative contribution of these two mechanisms was highly dependent on the set cathode potential. Both cyclic voltammetry tests and batch potentiostatic experiments indicated that the capacity for extracellular electron transfer was a constitutive trait of the hydrogenophilic methanogenic culture. In principle, both electrons and carbon dioxide required for methane production could be obtained from a bioanode carrying out the oxidation of waste organic substrates.

  7. Distribution and air-sea fluxes of carbon dioxide on the Chukchi Sea shelf

    NASA Astrophysics Data System (ADS)

    Pipko, I. I.; Pugach, S. P.; Repina, I. A.; Dudarev, O. V.; Charkin, A. N.; Semiletov, I. P.

    2015-12-01

    This article presents the results of long-term studies of the dynamics of carbonate parameters and air-sea carbon dioxide fluxes on the Chukchi Sea shelf during the summer. As a result of the interaction of physical and biological factors, the surface waters on the west of Chukchi Sea were undersaturated with carbon dioxide when compared with atmospheric air; the partial pressure of CO2 varied in the range from 134 to 359 μatm. The average value of CO2 flux in the Chukchi Sea per unit area varied in the range from-2.4 to-22.0 mmol /(m2 day), which is significantly higher than the average value of CO2 flux in the World Ocean. It has been estimated that the minimal mass of C absorbed by the surface of Chukchi Sea from the atmosphere during ice-free season is 13 × 1012 g; a great part of this carbon is transported to the deeper layers of sea and isolated from the atmosphere for a long period of time. The studies of the carbonate system of the Chukchi Sea, especially of its western part, will provide some new data on the fluxes of carbon dioxide in the Arctic Ocean and their changes. Our analysis can be used for an interpretation of the satellite assessment of CO2 fluxes and dissolved CO2 distribution in the upper layers of the ocean.

  8. Coastal CO2 climatology of Oahu, Hawaii: Six years of high resolution time-series data

    NASA Astrophysics Data System (ADS)

    Terlouw, G. J.; Drupp, P. S.; De Carlo, E. H.; Tomlinson, M.

    2014-12-01

    Six years of high resolution pCO2, water quality, and meteorological data were used to calculate air-sea CO2 fluxes on yearly, seasonal and monthly timescales, and relate the temporal and spatial variation in CO2 fluxes to meteorological events and land derived inputs. Three MAPCO2 buoys are deployed in coastal waters of Oahu as part of the NOAA/PMEL Carbon Program, that autonomously collects CO2 and water quality data at 3-hour intervals. The buoys are located on a backreef in Kaneohe Bay and two fringing reef sites on Oahu's south shore, the latter two in open ocean like conditions but with one also influenced by fluvial inputs. Data for this study were collected from June 2008 to July 2014. Mean pCO2 values at the Ala Wai, Kilo Nalu and CRIMP2 buoys were 396, 381 and 447μatm, respectively, with mean daily ranges of 51, 32 and 190 μatm, respectively. The daily range in pCO2 is largest at CRIMP2, reflecting a combination of higher primary production and respiration, vigorous calcification and longer water residence time within the barrier reef environment. Net annualized air-sea CO2 fluxes of the entire study period were 0.083, -0.014 and 1.167 mol C m-2 year-1 for Ala Wai, Kilo Nalu and CRIMP2, respectively. Positive values indicate a CO2 flux from the water to the atmosphere (source behavior), and negative values from the atmosphere to the water (sink behavior). This presentation will also discuss the effects physical and biogeochemical processes on the magnitude and variability of air-sea CO2 fluxes. We observe a negative correlation between CO2 flux and rainfall over monthly, seasonal, and annual timescales. This correlation however, can partly be explained by temperature, because increased rainfall is more common during the colder winter months. Nevertheless, rainfall affects CO2 fluxes, both by rain-induced nutrient and organic matter runoff, as well as the physical effect of raindrops on air-sea gas exchange and the dilution of the air-sea boundary layer

  9. Heat-transfer distributions on biconics at incidence in hypersonic-hypervelocity He, N2, air, and CO2 flows

    NASA Technical Reports Server (NTRS)

    Miller, C. G.; Micol, J. R.; Gnoffo, P. A.; Wilder, S. E.

    1983-01-01

    Laminar heat transfer rates were measured on spherically blunted, 13 deg/7 deg on axis and bent biconics (fore cone bent 7 deg upward relative to aft cone) at hypersonic hypervelocity flow conditions in the Langley Expansion Tube. Freestream velocities from 4.5 to 6.9 km/sec and Mach numbers from 6 to 9 were generated using helium, nitrogen, air, and carbon dioxide test gases, resulting in normal shock density ratios from 4 to 19. Angle of attack, referenced to the axis of the aft cone, was varied from 0 to 20 deg in 4 deg increments. The effect of nose bend, angle of attack, and real gas phenomena on heating distributions are presented along with comparisons of measurement to prediction from a code which solves the three dimensional parabolized Navier-Stokes equations.

  10. Origin of the Red Shift for the Lowest Singlet π → π* Charge-Transfer Absorption of p-Nitroaniline in Supercritical CO2.

    PubMed

    Hidalgo, Marcelo; Rivelino, Roberto; Canuto, Sylvio

    2014-04-08

    The origin of the unusual solvatochromic shift of p-nitroaniline (PNA) in supercritical carbon dioxide (SCCO2) is theoretically investigated on the basis of experimental data. Ab initio quantum chemistry calculations have been employed to unveil the interaction of CO2 with this archetypical molecule. It is demonstrated that the nitro group of PNA works as an electron-donating site binding to the electron-deficient carbon atom of CO2, most probably via a Lewis acid-base interaction. Moreover, a cooperative C-H···O hydrogen bond seems to act as an additional stabilizing source during the solvation process of PNA in SCCO2. To support the influence of solute-solvent specific interactions on the lowest singlet π → π* charge-transfer excitation, we perform a sequential Monte Carlo time-dependent density functional theory simulation to evaluate the excited states of PNA in SCCO2 (T = 315 K, ρ = 0.81 g/cm(3)). A critical assessment of this simulation, compared to calculations carried out within the polarized continuum model, gives strong evidence that our proposed complexes are important in describing the solvatochromic shift of PNA in SCCO2. The calculated red shift from the gas phase accounts for 66% to 80% (depending on the degree of complexation) of the experimental data. Finally, these results also alleviate possible failures commonly attributed to long-range corrected functionals in reproducing the solvatochromism of PNA.

  11. Development of Unmanned Airborne System (UAS) instrumentation for air-sea-ice interaction research

    NASA Astrophysics Data System (ADS)

    Reineman, B. D.; Lenain, L.; Melville, W. K.

    2011-12-01

    We have developed Unmanned Airborne System (UAS) instrumentation packages to directly measure air-sea momentum transfer, as well as latent, sensible, and radiative heat fluxes, topography, and surface wave kinematics. Two UAS (BAE Manta C1s) flying in vertical formation over the ocean will allow the direct measurement of air-sea fluxes within the marine atmospheric boundary layer, and, with onboard high-resolution video and laser altimetry, simultaneous observation of sea surface kinematics and sea-ice topography. The low altitude required for accurate air-sea or air-ice flux measurements is below the typical safety limit of manned research aircraft; however, with advancements in laser altimeters, small-aircraft flight control, and real-time Differential GPS, it now is within the capability of the UAS platform. Fast response turbulence, hygrometer, and temperature probes in the lower UAS permit surface layer flux measurements, and short and long wave radiometers in the upper UAS allow the determination of net radiation, surface temperature, and albedo. Engineering test flights of the two UAS over land were performed in January 2011 at Camp Roberts, CA. The tests demonstrated the capability of the systems to measure vertical profiles of georeferenced wind, temperature, and moisture content, as well as momentum flux and sensible, latent, and radiative heat fluxes. UAS-derived fluxes from low-altitude (20 -- 30 m) flights are in agreement with fluxes measured by a nearby tower-mounted sonic anemometer-based eddy covariance system. We present a description of the instrumentation, a summary of results from flight tests, and discuss potential applications of these instrumented platforms for air-sea-ice interaction studies.

  12. Transferable force-field for modelling of CO2, N2, O2 and Ar in all silica and Na+ exchanged zeolites

    NASA Astrophysics Data System (ADS)

    Vujić, Bojan; Lyubartsev, Alexander P.

    2016-05-01

    In this work we propose a new force field for modelling of adsorption of CO2, N2, O2 and Ar in all silica and Na+ exchanged Si-Al zeolites. The force field has a standard molecular-mechanical functional form with electrostatic and Lennard-Jones interactions satisfying Lorentz-Berthelot mixing rules and thus has a potential for further extension in terms of new molecular types. The parameters for the zeolite framework atom types are optimized by an iterative procedure minimizing the difference with experimental adsorption data for a number of different zeolite structures and Si:Al ratios. The new force field shows a good agreement with available experimental data including those not used in the optimization procedure, and which also shows a reasonable transferability within different zeolite topologies. We suggest a potential usage in screening of different zeolite structures for carbon capture and storage process, and more generally, for separation of other gases.

  13. Evaluation and Countermeasures of Convective Heat Transfer on Thermal Conductivity Measurement Using the Peltier Effect and Application to Supercritical CO2

    NASA Astrophysics Data System (ADS)

    Chen, Zai-hua; Tozaki, Ken-ichi; Nishikawa, Keiko

    1999-12-01

    In the previous paper, the present authors reported a newlydeveloped method of thermal conductivity measurement for fluids usinga thermoelectric module. It was very simple and effective for samplesin supercritical states. However, the countermeasures against thermalperturbation were insufficient. In the present work, some improvementshave been made on the apparatus to eliminate thermal convection. Theconvective heat transfer effect on the measurement has been evaluatedby varying the temperature difference across the sample layer. It hasbeen found that the convection-free conductivity for critical andsupercritical fluids can be determined by extrapolation of thetemperature difference to 0. The thermal conductivity ofsupercritical CO2 measured by the improved method is presented,including the states near the critical point.

  14. Sea surface carbon dioxide at the Georgia time series site (2006-2007): Air-sea flux and controlling processes

    NASA Astrophysics Data System (ADS)

    Xue, Liang; Cai, Wei-Jun; Hu, Xinping; Sabine, Christopher; Jones, Stacy; Sutton, Adrienne J.; Jiang, Li-Qing; Reimer, Janet J.

    2016-01-01

    Carbon dioxide partial pressure (pCO2) in surface seawater was continuously recorded every three hours from 18 July 2006 through 31 October 2007 using a moored autonomous pCO2 (MAPCO2) system deployed on the Gray's Reef buoy off the coast of Georgia, USA. Surface water pCO2 (average 373 ± 52 μatm) showed a clear seasonal pattern, undersaturated with respect to the atmosphere in cold months and generally oversaturated in warm months. High temporal resolution observations revealed important events not captured in previous ship-based observations, such as sporadically occurring biological CO2 uptake during April-June 2007. In addition to a qualitative analysis of the primary drivers of pCO2 variability based on property regressions, we quantified contributions of temperature, air-sea exchange, mixing, and biological processes to monthly pCO2 variations using a 1-D mass budget model. Although temperature played a dominant role in the annual cycle of pCO2, river inputs especially in the wet season, biological respiration in peak summer, and biological production during April-June 2007 also substantially influenced seawater pCO2. Furthermore, sea surface pCO2 was higher in September-October 2007 than in September-October 2006, associated with increased river inputs in fall 2007. On an annual basis this site was a moderate atmospheric CO2 sink, and was autotrophic as revealed by monthly mean net community production (NCP) in the mixed layer. If the sporadic short productive events during April-May 2007 were missed by the sampling schedule, one would conclude erroneously that the site is heterotrophic. While previous ship-based pCO2 data collected around this buoy site agreed with the buoy CO2 data on seasonal scales, high resolution buoy observations revealed that the cruise-based surveys undersampled temporal variability in coastal waters, which could greatly bias the estimates of air-sea CO2 fluxes or annual NCP, and even produce contradictory results.

  15. Cation diffusion in the electrical double layer enhances the mass transfer rates for Sr2+, Co2+ and Zn2+ in compacted illite

    NASA Astrophysics Data System (ADS)

    Glaus, M. A.; Aertsens, M.; Appelo, C. A. J.; Kupcik, T.; Maes, N.; Van Laer, L.; Van Loon, L. R.

    2015-09-01

    Enhanced mass transfer rates have been frequently observed in diffusion studies with alkaline and earth alkaline elements in compacted clay minerals and clay rocks. Whether this phenomenon - often termed surface diffusion - is also relevant for more strongly sorbing species is an open question. We therefore investigated the diffusion of Sr2+, Co2+ and Zn2+ in compacted illite with respect to variations of the concentration of the background electrolyte, pH and carbonate. New experimental techniques were developed in order to avoid artefacts stemming from the confinement of the clay sample. A distinct dependence of the effective diffusion coefficients on the concentration of the background electrolyte was observed for all three elements. A similar correlation was found for the sorption distribution ratio (Rd) derived from tracer breakthrough in the case of Sr2+, while this dependence was much weaker for Co2+ and Zn2+. Model calculations using Phreeqc resulted in a good agreement with the experimental data when it was assumed that the cationic species, present in the electrical double layer (EDL) of the charged clay surface, are mobile. Species bound to the specific surface complexation sites at the clay edges were assumed to be immobile. An assessment of the mobility of the type of cationic elements studied here in argillaceous media thus requires an analysis of their distribution among specifically sorbed surface species and species in the EDL. The normal approach of deriving unknown effective diffusion coefficients from reference values of an uncharged water tracer may significantly underestimate the mobility of metal cations in argillaceous media.

  16. CO2-Neutral Fuels

    NASA Astrophysics Data System (ADS)

    Goede, Adelbert; van de Sanden, Richard

    2016-06-01

    Mimicking the biogeochemical cycle of System Earth, synthetic hydrocarbon fuels are produced from recycled CO2 and H2O powered by renewable energy. Recapturing CO2 after use closes the carbon cycle, rendering the fuel cycle CO2 neutral. Non-equilibrium molecular CO2 vibrations are key to high energy efficiency.

  17. A significant net sink for CO2 in Tokyo Bay

    NASA Astrophysics Data System (ADS)

    Kubo, Atsushi; Maeda, Yosaku; Kanda, Jota

    2017-03-01

    Most estuaries and inland waters are significant source for atmospheric CO2 because of input of terrestrial inorganic carbon and mineralization of terrestrially supplied organic carbon. In contrast to most coastal waters, some estuaries with small freshwater discharge are weak source or sometimes sink for CO2. Extensive surveys of pCO2 in Tokyo Bay showed that the overall bay acts as a strong net sink for atmospheric CO2. Although small area was a consistent source for CO2, active photosynthesis driven by nutrient loading from the land overwhelmed the CO2 budget in the bay. Here we show a comprehensive scheme with a border where air-sea CO2 flux was ±0 between nearshore waters emitting CO2 and offshore waters absorbing CO2. The border in Tokyo Bay was extremely shifted toward the land-side. The shift is characteristic of highly urbanized coastal waters with an extensive sewage treatment system in the catchment area. Because highly urbanized coastal areas worldwide are expected to quadruple by 2050, coastal waters such as Tokyo Bay are expected to increase as well. Through extrapolation of Tokyo Bay data, CO2 emission from global estuaries would be expected to decrease roughly from the current 0.074 PgC year‑1 to 0.014 PgC year‑1 in 2050.

  18. A significant net sink for CO2 in Tokyo Bay.

    PubMed

    Kubo, Atsushi; Maeda, Yosaku; Kanda, Jota

    2017-03-13

    Most estuaries and inland waters are significant source for atmospheric CO2 because of input of terrestrial inorganic carbon and mineralization of terrestrially supplied organic carbon. In contrast to most coastal waters, some estuaries with small freshwater discharge are weak source or sometimes sink for CO2. Extensive surveys of pCO2 in Tokyo Bay showed that the overall bay acts as a strong net sink for atmospheric CO2. Although small area was a consistent source for CO2, active photosynthesis driven by nutrient loading from the land overwhelmed the CO2 budget in the bay. Here we show a comprehensive scheme with a border where air-sea CO2 flux was ±0 between nearshore waters emitting CO2 and offshore waters absorbing CO2. The border in Tokyo Bay was extremely shifted toward the land-side. The shift is characteristic of highly urbanized coastal waters with an extensive sewage treatment system in the catchment area. Because highly urbanized coastal areas worldwide are expected to quadruple by 2050, coastal waters such as Tokyo Bay are expected to increase as well. Through extrapolation of Tokyo Bay data, CO2 emission from global estuaries would be expected to decrease roughly from the current 0.074 PgC year(-1) to 0.014 PgC year(-1) in 2050.

  19. A significant net sink for CO2 in Tokyo Bay

    PubMed Central

    Kubo, Atsushi; Maeda, Yosaku; Kanda, Jota

    2017-01-01

    Most estuaries and inland waters are significant source for atmospheric CO2 because of input of terrestrial inorganic carbon and mineralization of terrestrially supplied organic carbon. In contrast to most coastal waters, some estuaries with small freshwater discharge are weak source or sometimes sink for CO2. Extensive surveys of pCO2 in Tokyo Bay showed that the overall bay acts as a strong net sink for atmospheric CO2. Although small area was a consistent source for CO2, active photosynthesis driven by nutrient loading from the land overwhelmed the CO2 budget in the bay. Here we show a comprehensive scheme with a border where air-sea CO2 flux was ±0 between nearshore waters emitting CO2 and offshore waters absorbing CO2. The border in Tokyo Bay was extremely shifted toward the land-side. The shift is characteristic of highly urbanized coastal waters with an extensive sewage treatment system in the catchment area. Because highly urbanized coastal areas worldwide are expected to quadruple by 2050, coastal waters such as Tokyo Bay are expected to increase as well. Through extrapolation of Tokyo Bay data, CO2 emission from global estuaries would be expected to decrease roughly from the current 0.074 PgC year−1 to 0.014 PgC year−1 in 2050. PMID:28287153

  20. Net uptake of atmospheric CO2 by coastal submerged aquatic vegetation.

    PubMed

    Tokoro, Tatsuki; Hosokawa, Shinya; Miyoshi, Eiichi; Tada, Kazufumi; Watanabe, Kenta; Montani, Shigeru; Kayanne, Hajime; Kuwae, Tomohiro

    2014-06-01

    'Blue Carbon', which is carbon captured by marine living organisms, has recently been highlighted as a new option for climate change mitigation initiatives. In particular, coastal ecosystems have been recognized as significant carbon stocks because of their high burial rates and long-term sequestration of carbon. However, the direct contribution of Blue Carbon to the uptake of atmospheric CO2 through air-sea gas exchange remains unclear. We performed in situ measurements of carbon flows, including air-sea CO2 fluxes, dissolved inorganic carbon changes, net ecosystem production, and carbon burial rates in the boreal (Furen), temperate (Kurihama), and subtropical (Fukido) seagrass meadows of Japan from 2010 to 2013. In particular, the air-sea CO2 flux was measured using three methods: the bulk formula method, the floating chamber method, and the eddy covariance method. Our empirical results show that submerged autotrophic vegetation in shallow coastal waters can be functionally a sink for atmospheric CO2. This finding is contrary to the conventional perception that most near-shore ecosystems are sources of atmospheric CO2. The key factor determining whether or not coastal ecosystems directly decrease the concentration of atmospheric CO2 may be net ecosystem production. This study thus identifies a new ecosystem function of coastal vegetated systems; they are direct sinks of atmospheric CO2.

  1. Net uptake of atmospheric CO2 by coastal submerged aquatic vegetation

    PubMed Central

    Tokoro, Tatsuki; Hosokawa, Shinya; Miyoshi, Eiichi; Tada, Kazufumi; Watanabe, Kenta; Montani, Shigeru; Kayanne, Hajime; Kuwae, Tomohiro

    2014-01-01

    ‘Blue Carbon’, which is carbon captured by marine living organisms, has recently been highlighted as a new option for climate change mitigation initiatives. In particular, coastal ecosystems have been recognized as significant carbon stocks because of their high burial rates and long-term sequestration of carbon. However, the direct contribution of Blue Carbon to the uptake of atmospheric CO2 through air-sea gas exchange remains unclear. We performed in situ measurements of carbon flows, including air-sea CO2 fluxes, dissolved inorganic carbon changes, net ecosystem production, and carbon burial rates in the boreal (Furen), temperate (Kurihama), and subtropical (Fukido) seagrass meadows of Japan from 2010 to 2013. In particular, the air-sea CO2 flux was measured using three methods: the bulk formula method, the floating chamber method, and the eddy covariance method. Our empirical results show that submerged autotrophic vegetation in shallow coastal waters can be functionally a sink for atmospheric CO2. This finding is contrary to the conventional perception that most near-shore ecosystems are sources of atmospheric CO2. The key factor determining whether or not coastal ecosystems directly decrease the concentration of atmospheric CO2 may be net ecosystem production. This study thus identifies a new ecosystem function of coastal vegetated systems; they are direct sinks of atmospheric CO2. PMID:24623530

  2. Air-sea interactions in sea surface temperature frontal region

    NASA Astrophysics Data System (ADS)

    Pianezze, Joris; Redelsperger, Jean-Luc; Ardhuin, Fabrice; Reynaud, Thierry; Marié, Louis; Bouin, Marie-Noelle; Garnier, Valerie

    2015-04-01

    Representation of air-sea exchanges in coastal, regional and global models represent a challenge firstly due to the small scale of acting turbulent processes comparatively to the resolved scales of these models. Beyond this subgrid parameterization issue, a comprehensive understanding of air-sea interactions at the turbulent process scales is still lacking. Many successful efforts are dedicated to measure the energy and mass exchanges between atmosphere and ocean, including the effect of surface waves. In comparison less efforts are brought to understand the interactions between the atmospheric boundary layer and the oceanic mixing layer. In this regard, we are developing research mainly based on ideal and realistic numerical simulations which resolve very small scales (horizontal resolutions from 1 to 100 meters) in using grid nesting technics and coupled ocean-wave-atmosphere models. As a first step, the impact of marked gradients in sea surface temperatures (SST) on air-sea exchanges has been explored through realistic numerical simulations at 100m horizontal resolution. Results from simulations of a case observed during the FROMVAR experiment will be shown. The talk will mainly focus on the marked impact of SST front on the atmospheric boundary layer (stability and winds), the air-sea exchanges and surface parameters (rugosity, drag coefficient) Results will be also shown on the strong impact on the simulated atmosphere of small scale variability of SST field.

  3. Operationalizing Air-Sea Battle in the Pacific

    DTIC Science & Technology

    2015-02-01

    systems. 35. Chris Anderson, " Agricultural Drones ,• MIT ’Technology Review 117, no. 3 (May/June 2014): 58. 36. Van Thl et al., AirSea Battle: A Point...communications are re- established. These systems are vulnerable to antiair weapons; how- ever, 11relatively cheap drones with advanced sensors and

  4. Microphysics of Air-Sea Exchanges

    DTIC Science & Technology

    2006-06-30

    Elevation Gauges (LEGs) and a 2-D Imaging Slope Gauge (ISG) so that wave propagation was not disturbed by intrusive measurement techniques. In the LEG system...Technology, 18, 994-1013. Ocampo-Torres, F. J. and M. A. Donelan, 1994: Laboratory measurements of mass transfer of carbon dioxide and water vapour for

  5. Carbonate chemistry in the Mertz Polynya (East Antarctica): Biological and physical modification of dense water outflows and the export of anthropogenic CO2

    NASA Astrophysics Data System (ADS)

    Shadwick, E. H.; Tilbrook, B.; Williams, G. D.

    2014-01-01

    Dense shelf water (DSW) is formed in East Antarctica from enhanced sea-ice production driven by air-sea interaction in coastal polynyas. Cross-shelf export and downslope mixing of this DSW produces Antarctic Bottom Water, contributing to the lower limb of the global overturning circulation. We present biogeochemical observations from the Mertz Polynya region in summer 2007/2008, with additional observations from spring 2001 and winter 1996. The seasonal changes in mixed-layer carbonate chemistry are driven by a combination of air-sea CO2 exchange, biological activity and the formation and melt of sea-ice. The air-sea fluxes in 2008 were ˜15 mmol C m-2 d-1, and net community production, estimated from the summertime surface dissolved inorganic carbon (DIC) deficit, ranged from 0.9 to 1.2 mol C m-2 yr-1. We show that biological modification of carbonate chemistry over the shelf in summer preconditions the DSW outflows from the Adélie Depression. This process appears to supply both organic material, and water depleted in CO2, and with enhanced carbonate saturation state (relative to inflowing water), to coral communities on the slope. We combined model-based transports of exported DSW with the natural and anthropogenic (Cant) carbon concentrations and estimate that the annual outflows of DIC and Cant from the Mertz Polynya range from 320 to 560 Tg C yr-1, and from 3 to 6 Tg Cant yr-1, respectively. The formation and export of dense water from this region, and by extension all similar polynyas around Antarctica, is an effective mechanism for the transfer of anthropogenic carbon into the deep ocean.

  6. Energy transfer dynamics and kinetics of elementary processes (promoted) by gas-phase CO2 -N2 collisions: Selectivity control by the anisotropy of the interaction.

    PubMed

    Lombardi, Andrea; Pirani, Fernando; Laganà, Antonio; Bartolomei, Massimiliano

    2016-06-15

    In this work, we exploit a new formulation of the potential energy and of the related computational procedures, which embodies the coupling between the intra and intermolecular components, to characterize possible propensities of the collision dynamics in energy transfer processes of interest for simulation and control of phenomena occurring in a variety of equilibrium and nonequilibrium environments. The investigation reported in the paper focuses on the prototype CO2 -N2 system, whose intramolecular component of the interaction is modeled in terms of a many body expansion while the intermolecular component is modeled in terms of a recently developed bonds-as-interacting-molecular-centers' approach. The main advantage of this formulation of the potential energy surface is that of being (a) truly full dimensional (i.e., all the variations of the coordinates associated with the molecular vibrations and rotations on the geometrical and electronic structure of the monomers, are explicitly taken into account without freezing any bonds or angles), (b) more flexible than other usual formulations of the interaction and (c) well suited for fitting procedures better adhering to accurate ab initio data and sensitive to experimental arrangement dependent information. Specific attention has been given to the fact that a variation of vibrational and rotational energy has a higher (both qualitative and quantitative) impact on the energy transfer when a more accurate formulation of the intermolecular interaction (with respect to that obtained when using rigid monomers) is adopted. This makes the potential energy surface better suited for the kinetic modeling of gaseous mixtures in plasma, combustion and atmospheric chemistry computational applications. © 2016 Wiley Periodicals, Inc.

  7. CO2 -Responsive polymers.

    PubMed

    Lin, Shaojian; Theato, Patrick

    2013-07-25

    This Review focuses on the recent progress in the area of CO2 -responsive polymers and provides detailed descriptions of these existing examples. CO2 -responsive polymers can be categorized into three types based on their CO2 -responsive groups: amidine, amine, and carboxyl groups. Compared with traditional temperature, pH, or light stimuli-responsive polymers, CO2 -responsive polymers provide the advantage to use CO2 as a "green" trigger as well as to capture CO2 directly from air. In addition, the current challenges of CO2 -responsive polymers are discussed and the different solution methods are compared. Noteworthy, CO2 -responsive polymers are considered to have a prosperous future in various scientific areas.

  8. CO2 laser modeling

    NASA Technical Reports Server (NTRS)

    Johnson, Barry

    1992-01-01

    The topics covered include the following: (1) CO2 laser kinetics modeling; (2) gas lifetimes in pulsed CO2 lasers; (3) frequency chirp and laser pulse spectral analysis; (4) LAWS A' Design Study; and (5) discharge circuit components for LAWS. The appendices include LAWS Memos, computer modeling of pulsed CO2 lasers for lidar applications, discharge circuit considerations for pulsed CO2 lidars, and presentation made at the Code RC Review.

  9. Annual sea ice. An air-sea gas exchange moderator

    SciTech Connect

    Gosink, T.A.; Kelley, J.J.

    1982-01-01

    Arctic annual sea ice, particularly when it is relatively warm (> -15/sup 0/C) permits significant gas exchange between the sea and air throughout the entire year. Sea ice, particularly annual sea ice, differs from freshwater ice with respect to its permeability to gases. The presence of brine allows for significant air-sea-ice exchange of CO/sub 2/ throughout the winter, which may significantly affect the global carbon dioxide balance. Other trace gases are also noted to be enriched in sea ice, but less is known about their importance to air-sea-interactions at this time. Both physical and biological factors cause and modify evolution of gases from the surface of sea ice. Quantitative and qualitative descriptions of the nature and physical behavior of sea ice with respect to brine and gases are discussed.

  10. Climatological mean and decadal change in surface ocean pCO 2, and net sea-air CO 2 flux over the global oceans

    NASA Astrophysics Data System (ADS)

    Takahashi, Taro; Sutherland, Stewart C.; Wanninkhof, Rik; Sweeney, Colm; Feely, Richard A.; Chipman, David W.; Hales, Burke; Friederich, Gernot; Chavez, Francisco; Sabine, Christopher; Watson, Andrew; Bakker, Dorothee C. E.; Schuster, Ute; Metzl, Nicolas; Yoshikawa-Inoue, Hisayuki; Ishii, Masao; Midorikawa, Takashi; Nojiri, Yukihiro; Körtzinger, Arne; Steinhoff, Tobias; Hoppema, Mario; Olafsson, Jon; Arnarson, Thorarinn S.; Tilbrook, Bronte; Johannessen, Truls; Olsen, Are; Bellerby, Richard; Wong, C. S.; Delille, Bruno; Bates, N. R.; de Baar, Hein J. W.

    2009-04-01

    A climatological mean distribution for the surface water pCO 2 over the global oceans in non-El Niño conditions has been constructed with spatial resolution of 4° (latitude) ×5° (longitude) for a reference year 2000 based upon about 3 million measurements of surface water pCO 2 obtained from 1970 to 2007. The database used for this study is about 3 times larger than the 0.94 million used for our earlier paper [Takahashi et al., 2002. Global sea-air CO 2 flux based on climatological surface ocean pCO 2, and seasonal biological and temperature effects. Deep-Sea Res. II, 49, 1601-1622]. A time-trend analysis using deseasonalized surface water pCO 2 data in portions of the North Atlantic, North and South Pacific and Southern Oceans (which cover about 27% of the global ocean areas) indicates that the surface water pCO 2 over these oceanic areas has increased on average at a mean rate of 1.5 μatm y -1 with basin-specific rates varying between 1.2±0.5 and 2.1±0.4 μatm y -1. A global ocean database for a single reference year 2000 is assembled using this mean rate for correcting observations made in different years to the reference year. The observations made during El Niño periods in the equatorial Pacific and those made in coastal zones are excluded from the database. Seasonal changes in the surface water pCO 2 and the sea-air pCO 2 difference over four climatic zones in the Atlantic, Pacific, Indian and Southern Oceans are presented. Over the Southern Ocean seasonal ice zone, the seasonality is complex. Although it cannot be thoroughly documented due to the limited extent of observations, seasonal changes in pCO 2 are approximated by using the data for under-ice waters during austral winter and those for the marginal ice and ice-free zones. The net air-sea CO 2 flux is estimated using the sea-air pCO 2 difference and the air-sea gas transfer rate that is parameterized as a function of (wind speed) 2 with a scaling factor of 0.26. This is estimated by inverting

  11. Ocean Winds and Turbulent Air-Sea Fluxes Inferred From Remote Sensing

    NASA Technical Reports Server (NTRS)

    Bourassa, Mark A.; Gille, Sarah T.; Jackson, Daren L.; Roberts, J. Brent; Wick, Gary A.

    2010-01-01

    Air-sea turbulent fluxes determine the exchange of momentum, heat, freshwater, and gas between the atmosphere and ocean. These exchange processes are critical to a broad range of research questions spanning length scales from meters to thousands of kilometers and time scales from hours to decades. Examples are discussed (section 2). The estimation of surface turbulent fluxes from satellite is challenging and fraught with considerable errors (section 3); however, recent developments in retrievals (section 3) will greatly reduce these errors. Goals for the future observing system are summarized in section 4. Surface fluxes are defined as the rate per unit area at which something (e.g., momentum, energy, moisture, or CO Z ) is transferred across the air/sea interface. Wind- and buoyancy-driven surface fluxes are called surface turbulent fluxes because the mixing and transport are due to turbulence. Examples of nonturbulent processes are radiative fluxes (e.g., solar radiation) and precipitation (Schmitt et al., 2010). Turbulent fluxes are strongly dependent on wind speed; therefore, observations of wind speed are critical for the calculation of all turbulent surface fluxes. Wind stress, the vertical transport of horizontal momentum, also depends on wind direction. Stress is very important for many ocean processes, including upper ocean currents (Dohan and Maximenko, 2010) and deep ocean currents (Lee et al., 2010). On short time scales, this horizontal transport is usually small compared to surface fluxes. For long-term processes, transport can be very important but again is usually small compared to surface fluxes.

  12. Quantifying the drivers of ocean-atmosphere CO2 fluxes

    NASA Astrophysics Data System (ADS)

    Lauderdale, Jonathan M.; Dutkiewicz, Stephanie; Williams, Richard G.; Follows, Michael J.

    2016-07-01

    A mechanistic framework for quantitatively mapping the regional drivers of air-sea CO2 fluxes at a global scale is developed. The framework evaluates the interplay between (1) surface heat and freshwater fluxes that influence the potential saturated carbon concentration, which depends on changes in sea surface temperature, salinity and alkalinity, (2) a residual, disequilibrium flux influenced by upwelling and entrainment of remineralized carbon- and nutrient-rich waters from the ocean interior, as well as rapid subduction of surface waters, (3) carbon uptake and export by biological activity as both soft tissue and carbonate, and (4) the effect on surface carbon concentrations due to freshwater precipitation or evaporation. In a steady state simulation of a coarse-resolution ocean circulation and biogeochemistry model, the sum of the individually determined components is close to the known total flux of the simulation. The leading order balance, identified in different dynamical regimes, is between the CO2 fluxes driven by surface heat fluxes and a combination of biologically driven carbon uptake and disequilibrium-driven carbon outgassing. The framework is still able to reconstruct simulated fluxes when evaluated using monthly averaged data and takes a form that can be applied consistently in models of different complexity and observations of the ocean. In this way, the framework may reveal differences in the balance of drivers acting across an ensemble of climate model simulations or be applied to an analysis and interpretation of the observed, real-world air-sea flux of CO2.

  13. CO2 laser resurfacing.

    PubMed

    Fitzpatrick, R E

    2001-07-01

    The CO2 Laser offers a variety of unique features in resurfacing facial photodamage and acne scarring. These include hemostasis, efficient removal of the epidermis in a single pass, thermally induced tissue tightening, and safe, predictable tissue interaction. Knowledge of these mechanisms will result in the capability of using the CO2 laser effectively and safely whether the goal is superficial or deep treatment.

  14. CO2 blood test

    MedlinePlus

    Bicarbonate test; HCO3-; Carbon dioxide test; TCO2; Total CO2; CO2 test - serum ... Many medicines can interfere with blood test results. Your health care provider will tell you if you need to stop taking any medicines before you have this test. DO ...

  15. AIRS Sea Surface Temperature and Pacific Decadal Oscillation

    NASA Astrophysics Data System (ADS)

    Chen, L. L.

    2015-12-01

    Atmospheric Infrared Sounder (AIRS) has been providing necessary measurements for long term atmospheric and surface processes aboard NASA' s Aqua polar orbiter since May 2002. Here, we use time series of AIRS sea surface temperature (SST) anomalies to show the time evolution of Pacific Decadal Oscillation (PDO) in the Gulf of Alaska (lon:-144.5, lat:54.5) from 2003 to 2014. PDO is connected to the first mode of North Pacific SST variability and is tele-connected to ENSO in the tropics. Further analysis of AIRS data can provide clarification of Pacific climate variability.

  16. Wave-Phase-Resolved Air-Sea Interaction

    DTIC Science & Technology

    2014-09-30

    to become an important asset in air-sea interaction research (Figure 3). Data from a scan-beam ADCP on FLIP was consistent with surface signatures...near-surface current velocity measured using a fan-beam ADCP mounted on FLIP’s hull. The bottom panel is a (contrast enhanced) image taken by the...video camera mounted on FLIP’s crows nest showing streak structures at the surface. The regions of convergence in the ADCP data are thought to correspond to the streak structures seen in the visible imagery.

  17. Measurements of the Air-Sea Interface from an Instrumented Small Buoy

    DTIC Science & Technology

    2011-09-01

    xiv THIS PAGE INTENTIONALLY LEFT BLANK xv LIST OF ACRONYMS AND ABBREVIATIONS ASIT Air Sea Interaction Tower ASIS Air-sea Interaction Spar...or the Air-sea Interaction Tower (ASIT, Edson et al. 2007). Research buoys are an alternative to the stabilized platforms. One such buoy is the...instrument suite was deployed on the R/V Sproul in both 2009 and 2010. The basic instruments included one or two flux measurement towers , a

  18. Outsourcing CO2 Emissions

    NASA Astrophysics Data System (ADS)

    Davis, S. J.; Caldeira, K. G.

    2009-12-01

    CO2 emissions from the burning of fossil fuels are the primary cause of global warming. Much attention has been focused on the CO2 directly emitted by each country, but relatively little attention has been paid to the amount of emissions associated with consumption of goods and services in each country. This consumption-based emissions inventory differs from the production-based inventory because of imports and exports of goods and services that, either directly or indirectly, involved CO2 emissions. Using the latest available data and reasonable assumptions regarding trans-shipment of embodied carbon through third-party countries, we developed a global consumption-based CO2 emissions inventory and have calculated associated consumption-based energy and carbon intensities. We find that, in 2004, 24% of CO2 emissions are effectively outsourced to other countries, with much of the developed world outsourcing CO2 emissions to emerging markets, principally China. Some wealthy countries, including Switzerland and Sweden, outsource over half of their consumption-based emissions, with many northern Europeans outsourcing more than three tons of emissions per person per year. The United States is both a big importer and exporter of emissions embodied in trade, outsourcing >2.6 tons of CO2 per person and at the same time as >2.0 tons of CO2 per person are outsourced to the United States. These large flows indicate that CO2 emissions embodied in trade must be taken into consideration when considering responsibility for increasing atmospheric greenhouse gas concentrations.

  19. The Role of the U.S. Army in Air Sea Battle

    DTIC Science & Technology

    2013-04-01

    national power to the Asia -Pacific region. The military contribution to this new national security strategy is termed “ Air Sea Battle.” Air Sea Battle...Asian focus under our new national security strategy. The military contribution to this new national security strategy is currently termed “ Air Sea...against a foe with anti-access and area-denial capabilities. As a concept, Air Sea Battle is not new . In one form or another, it has been around as a

  20. An improved model of radiative transfer for the NLTE problem in the NIR bands of CO2 and CO molecules in the daytime atmosphere of Mars. 1. Input data and calculation method

    NASA Astrophysics Data System (ADS)

    Ogibalov, V. P.; Shved, G. M.

    2016-09-01

    Advances in attacking the problem of radiative transfer in the near infrared (NIR) bands of CO2 and CO under nonlocal thermodynamic equilibrium (NLTE) conditions depend on the accuracy of taking into account the radiation processes and inelastic collisions of CO2 and CO molecules. The focus of the paper is to substantially improve the physical model of the problem and update the calculation method. It is the first time the surface albedo is introduced into the problem of the molecular emission under NLTE conditions. The values of the rate constants for inelastic molecular collisions and their temperature dependences have been radically updated. In some cases, since laboratory measurements of these constants are lacking, different versions are provided for them. The relative abundance of CO2 and CO isotopologues is based on the ratios of isotope abundances for the elements C and O obtained from the measurements in the atmosphere of Mars. The intensity of extraterrestrial solar NIR radiation is specified on the base of the high-accuracy ground-based measurements. In the method for calculating the populations of vibrational states, we pioneer in completely taking into account the overlapping of spectral lines in the NIR bands of CO2 and CO.

  1. Research in Observations of Oceanic Air/Sea Interaction

    NASA Technical Reports Server (NTRS)

    Long, David G.; Arnold, David V.

    1995-01-01

    The primary purpose of this research has been: (1) to develop an innovative research radar scatterometer system capable of directly measuring both the radar backscatter and the small-scale and large-scale ocean wave field simultaneously and (2) deploy this instrument to collect data to support studies of air/sea interaction. The instrument has been successfully completed and deployed. The system deployment lasted for six months during 1995. Results to date suggest that the data is remarkably useful in air/sea interaction studies. While the data analysis is continuing, two journal and fifteen conference papers have been published. Six papers are currently in review with two additional journal papers scheduled for publication. Three Master's theses on this research have been completed. A Ph.D. student is currently finalizing his dissertation which should be completed by the end of the calendar year. We have received additional 'mainstream' funding from the NASA oceans branch to continue data analysis and instrument operations. We are actively pursuing results from the data expect additional publications to follow. This final report briefly describes the instrument system we developed and results to-date from the deployment. Additional detail is contained in the attached papers selected from the bibliography.

  2. Modeling air/sea flux parameters in a coastal area: A comparative study of results from the TOGA COARE model and the NOAA Buoy model

    NASA Astrophysics Data System (ADS)

    Sopkin, Kristin; Mizak, Connie; Gilbert, Sherryl; Subramanian, Vembu; Luther, Mark; Poor, Noreen

    Because estuaries and coastal regions are particularly susceptible to nutrient over-enrichment due to their close proximity to source-rich regions, a goal of the BRACE study was to improve estimates of nitrogen air/sea transfer rates in the Tampa Bay Estuary. Our objective was to critically evaluate two air/sea gas exchange models to determine their efficacy for use in a coastal region, with the ultimate goal of improving nitrogen exchange estimates in Tampa Bay. We used meteorological data and oceanographic parameters collected hourly at an instrumented tower located in Middle Tampa Bay, Florida. The data was used to determine the friction velocity and the turbulent flux of heat and moisture across the air/sea interface and then compared with modeled parameters at the same offshore site. On average both models underpredicted sensible heat flux and there was considerable scatter in the data during stable conditions, indicating that nitrogen gas exchange rates may also be underestimated. Model improvement, however, was observed with friction velocity comparisons. Model inter-comparisons of sensible heat flux and friction velocity suggest excellent agreement between the TOGA COARE and the NOAA Buoy models, but model estimated heat transfer coefficients and latent heat fluxes did not agree as well. Based on our analysis, we conclude that both models are suitable for use in a coastal environment to estimate nitrogen air/sea gas exchange, although the NOAA Buoy model requires fewer meteorological inputs. However, if the purpose is to conduct more sophisticated microscale modeling of air/sea interactions, we recommend the TOGA COARE model.

  3. Comparison of metasomatic reactions between a common CO2-rich vein fluid and diverse wall rocks: intensive variables, mass transfers, and Au mineralization at Alleghany, California

    USGS Publications Warehouse

    Böhlke, J.K.

    1989-01-01

    The gold deposits at Alleghany, California, are typical of many epigenetic gold-bearing hydrothermal vein systems in metamorphic terranes worldwide. Detailed analyses of alteration halos in serpentinite, mafic amphibolite, and granite wall rocks at Alleghany indicate that widely contrasting deposit types, ranging from fuchsite-carbonate schists to pyrite-albitites, resulted when different wall rocks interacted with the same externally derived CO2-rich hydrothermal vein fluid. Patterns of element redistribution within halos and among lithologic units suggest a complex process involving fluid flow along vein fractures and diffusion (?? infiltration) normal to the veins. Wall rocks locally controlled both the directions and magnitudes of chemical fluxes across vein walls. -from Author

  4. Modeling of energy transfer from vibrationally excited CO2 molecules: cross sections and probabilities for kinetic modeling of atmospheres, flows, and plasmas.

    PubMed

    Lombardi, Andrea; Faginas-Lago, Noelia; Pacifici, Leonardo; Costantini, Alessandro

    2013-11-14

    We present extended applications of an established theoretical and computational machinery suitable for the study of the dynamics of CO2+CO2 collisions, focusing on vibrational energy exchange, considered over a wide range of energies and rotational temperatures. Calculations are based on quasi-classical trajectories on a potential energy function (a critical component of dynamics simulations), tailored to accurately describe the intermolecular interactions, modeled by the recently proposed bond-bond semiempirical formulation that allows the colliding molecules to be stretchable, rather than frozen at their equilibrium geometry. In a previous work, the same potential energy surface has been used to show that modifications in the geometry (and in physical properties such as polarizability and charge distribution) of the colliding partners affect the intermolecular interaction and determine the features of the energy exchange, to a large extent driven by long-range forces. As initial partitioning of the energy among the molecular degrees of freedom, we consider the excitation of the vibrational bending mode, assuming an initial rotational distribution and a rotational temperature. The role of the vibrational angular momentum is also carefully assessed. Results are obtained by portable implementations of this approach in a Grid-computing framework and on high performance platforms. Cross sections are basic ingredients to obtain rate constants of use in advanced state-to-state kinetic models, under equilibrium or nonequilibrium conditions, and this approach is suitable for gas dynamics applications to plasmas and modeling of hypersonic flows.

  5. Air-Sea Interactions over Lakes on Titan

    NASA Astrophysics Data System (ADS)

    Soto, Alejandro; Rafkin, Scot C. R.

    2016-10-01

    The exchange of methane between the atmosphere and surface liquid reservoirs dominates the short time-scale methanological cycle. In this study, previous two-dimensional simulations of the exchange of methane vapor, sensible heat and momentum between the atmosphere and lakes are updated with the inclusion of radiative forcing, three dimensions, and realistic coastlines. Titan's air-sea exchange in two dimensions indicated that the exchange process was self-limiting. Evaporation from lakes produced a shallow but extremely stable marine layer that suppressed turbulent exchange. Furthermore, the circulation associated with the higher buoyancy of methane-rich atmosphere over the lake was offset by the oppositely directed thermal sea breeze circulation, which muted the mean wind. Two major weaknesses of this previous work were the lack of radiative forcing and the imposition of two dimensionality, which limited the full range of dynamical solutions. Based on early theoretical studies, it was thought that magnitude of turbulent energy flux exchanges would be much larger than radiative fluxes, thereby justifying the neglect of radiation, but the two-dimensional simulations indicated that this was not a valid assumption. The dynamical limitations of two-dimensional simulations are well known. Vorticity stretching (i.e., circulation intensification through vertical motion) is not possible and it is also not possible to produce dynamically balanced gradient wind-type circulations. As well, the irregular shape of a realistic coastline cannot be expressed in two dimensions, and these realistic structures will generally induce complex convergence and divergence circulations in the atmosphere. The impact of radiative forcing and the addition of the third dimension on the air-sea exchange are presented.

  6. Spectral radiative transfer for the 4.0- to 5.0-micron bands of CO and CO2 with mild vibrational relaxation and Doppler shift

    NASA Astrophysics Data System (ADS)

    Limbaugh, C. C.; Hiers, R. S., III; Phillips, W. J.

    1990-06-01

    This paper presents representative results for line-by-line spectral calculations of the 4.3-micron band of CO2 and the 5.0-micron band of CO in a nozzle-constrained, vibrationally relaxing combustion flow. The effects of property gradients are included, with special emphasis on the effects of the frequency shift of the radiation and absorption due to the component of velocity along the line of sight. Broadband spectra resulting from the convolution of the line-by-line results with a broadband filter are examined. It is shown that the effect of the Doppler shift is to broaden the individual spectral features with an attendant increase in the emitted radiation. Spectral detail is lost because of the broadening, and the greatest effect on the magnitude of the emission is for those lines which are optically thick.

  7. Spatiotemporal variability of lake pCO2 and CO2 fluxes in a hemiboreal catchment

    NASA Astrophysics Data System (ADS)

    Natchimuthu, Sivakiruthika; Sundgren, Ingrid; Gâlfalk, Magnus; Klemedtsson, Leif; Bastviken, David

    2017-01-01

    Globally, lakes are frequently supersaturated with carbon dioxide (CO2) and are major emitters of carbon to the atmosphere. Recent studies have generated awareness of the high variability in pCO2aq (the partial pressure corresponding to the concentration in water) and CO2 fluxes to the atmosphere and the need for better accounting for this variability. However, studies simultaneously accounting for both spatial and temporal variability of pCO2aq and CO2 fluxes in lakes are rare. We measured pCO2aq (by both manual sampling and mini loggers) and CO2 fluxes, covering spatial variability in open water areas of three lakes of different character in a Swedish catchment for 2 years. Spatial pCO2aq variability within lakes was linked to distance from shore, proximity to stream inlets, and deepwater upwelling events. Temporally, pCO2aq variability was linked with variability in dissolved organic carbon, total nitrogen, and dissolved oxygen. While previous studies over short time periods (1 to 6 h) observed gas transfer velocity (k) to be more variable than pCO2aq, our work shows that over longer time (days to weeks) pCO2aq variability was greater and affected CO2 fluxes much more than k. We demonstrate that ≥8 measurement days distributed over multiple seasons in combination with sufficient spatial coverage (≥8 locations during stratification periods and 5 or less in spring and autumn) are a key for representative yearly whole lake flux estimates. This study illustrates the importance of considering spatiotemporal variability in pCO2aq and CO2 fluxes to generate representative whole lake estimates.

  8. CO2-neutral fuels

    NASA Astrophysics Data System (ADS)

    Goede, A. P. H.

    2015-08-01

    The need for storage of renewable energy (RE) generated by photovoltaic, concentrated solar and wind arises from the fact that supply and demand are ill-matched both geographically and temporarily. This already causes problems of overcapacity and grid congestion in countries where the fraction of RE exceeds the 20% level. A system approach is needed, which focusses not only on the energy source, but includes conversion, storage, transport, distribution, use and, last but not least, the recycling of waste. Furthermore, there is a need for more flexibility in the energy system, rather than relying on electrification, integration with other energy systems, for example the gas network, would yield a system less vulnerable to failure and better adapted to requirements. For example, long-term large-scale storage of electrical energy is limited by capacity, yet needed to cover weekly to seasonal demand. This limitation can be overcome by coupling the electricity net to the gas system, considering the fact that the Dutch gas network alone has a storage capacity of 552 TWh, sufficient to cover the entire EU energy demand for over a month. This lecture explores energy storage in chemicals bonds. The focus is on chemicals other than hydrogen, taking advantage of the higher volumetric energy density of hydrocarbons, in this case methane, which has an approximate 3.5 times higher volumetric energy density. More importantly, it allows the ready use of existing gas infrastructure for energy storage, transport and distribution. Intermittent wind electricity generated is converted into synthetic methane, the Power to Gas (P2G) scheme, by splitting feedstock CO2 and H2O into synthesis gas, a mixture of CO and H2. Syngas plays a central role in the synthesis of a range of hydrocarbon products, including methane, diesel and dimethyl ether. The splitting is accomplished by innovative means; plasmolysis and high-temperature solid oxygen electrolysis. A CO2-neutral fuel cycle is

  9. Impacts and effects of mesoscale ocean eddies on ocean carbon storage and atmospheric pCO2

    NASA Astrophysics Data System (ADS)

    Munday, D. R.; Johnson, H. L.; Marshall, D. P.

    2014-08-01

    An idealized numerical ocean model is used to investigate the sensitivity of the partial pressure of atmospheric carbon dioxide (pCO2) to changes in surface wind stress when mesoscale eddies are permitted in the flow. When wind stress increases, pCO_2 increases, and vice versa. The introduction of mesoscale eddies reduces the overall sensitivity of pCO2 by changing the sensitivity of ocean carbon storage due to the saturation state of carbon dioxide, the net air-sea disequilibrium, soft tissue carbon, and the carbonate pump. However, a full carbon pump decomposition shows different responses for different ocean carbon storage terms. For example, air-sea disequilibrium is actually more sensitive to increased winds at eddy-permitting resolution, whereas soft tissue carbon is much less sensitive to wind changes in an eddy-permitting ocean. Changes in pycnocline depth and the strength of both upper and lower cells of the meridional overturning circulation affect this sensitivity.

  10. Estimating lake-atmosphere CO2 exchange

    USGS Publications Warehouse

    Anderson, D.E.; Striegl, R.G.; Stannard, D.I.; Michmerhuizen, C.M.; McConnaughey, T.A.; LaBaugh, J.W.

    1999-01-01

    Lake-atmosphere CO2 flux was directly measured above a small, woodland lake using the eddy covariance technique and compared with fluxes deduced from changes in measured lake-water CO2 storage and with flux predictions from boundary-layer and surface-renewal models. Over a 3-yr period, lake-atmosphere exchanges of CO2 were measured over 5 weeks in spring, summer, and fall. Observed springtime CO2 efflux was large (2.3-2.7 ??mol m-2 s-1) immediately after lake-thaw. That efflux decreased exponentially with time to less than 0.2 ??mol m-2 s-1 within 2 weeks. Substantial interannual variability was found in the magnitudes of springtime efflux, surface water CO2 concentrations, lake CO2 storage, and meteorological conditions. Summertime measurements show a weak diurnal trend with a small average downward flux (-0.17 ??mol m-2 s-1) to the lake's surface, while late fall flux was trendless and smaller (-0.0021 ??mol m-2 s-1). Large springtime efflux afforded an opportunity to make direct measurement of lake-atmosphere fluxes well above the detection limits of eddy covariance instruments, facilitating the testing of different gas flux methodologies and air-water gas-transfer models. Although there was an overall agreement in fluxes determined by eddy covariance and those calculated from lake-water storage change in CO2, agreement was inconsistent between eddy covariance flux measurements and fluxes predicted by boundary-layer and surface-renewal models. Comparison of measured and modeled transfer velocities for CO2, along with measured and modeled cumulative CO2 flux, indicates that in most instances the surface-renewal model underpredicts actual flux. Greater underestimates were found with comparisons involving homogeneous boundary-layer models. No physical mechanism responsible for the inconsistencies was identified by analyzing coincidentally measured environmental variables.

  11. The non-mass-dependent oxygen isotopic composition of CO2 formed by O+CO: Anomalous isotope effects in the O+CO recombination reaction or transfer from ozone?

    NASA Astrophysics Data System (ADS)

    Estillore, A. D.; Wiegel, A. A.; Boering, K. A.

    2013-12-01

    A number of oxygen-containing atmospheric species are now known to have non-mass-dependent triple oxygen isotope compositions (i.e., non-mass-dependent relationships between 16O, 17O, and 18O), which in turn are now being broadly applied as probes of biogeochemical cycles and chemical reactivity or as climate proxies on a variety of timescales. For many species, their non-mass-dependent oxygen isotope compositions derive from chemical or O(1D)-mediated photochemical transfer from ozone, which is non-mass-dependently enriched in 17O and 18O due to large non-mass-dependent kinetic isotope effects in the ozone recombination reaction, O+O2+M. For other species, however, there may also be additional non-mass-dependent kinetic isotope effects involved beyond ozone formation. The distinction is important both with respect to the biogeochemical and climate applications and to obtaining a deeper fundamental understanding of non-mass-dependent isotope fractionation in general. In work to be presented here, we have used a photochemical kinetics model to understand the isotopic composition of CO2 formed by O+CO+M in a mixture of O2 and CO gases irradiated with UV light at several wavelengths. We compare our model results with experimental results from Bhattacharya and Thiemens [Z. Naturforsch. 44a, 435-444 (1989)] and Pandey and Bhattacharya [J. Chem. Phys. 124, 234301 (2006)] in order to evaluate the extent to which the non-mass-dependent isotopic composition of CO2 derives from photochemical transfer from ozone formed during the experiment versus possible non-mass-dependent isotope effects in the CO2 recombination reaction.

  12. Assessing the potential for dimethylsulfide enrichment at the sea surface and its influence on air-sea flux

    NASA Astrophysics Data System (ADS)

    Walker, Carolyn F.; Harvey, Mike J.; Smith, Murray J.; Bell, Thomas G.; Saltzman, Eric S.; Marriner, Andrew S.; McGregor, John A.; Law, Cliff S.

    2016-09-01

    The flux of dimethylsulfide (DMS) to the atmosphere is generally inferred using water sampled at or below 2 m depth, thereby excluding any concentration anomalies at the air-sea interface. Two independent techniques were used to assess the potential for near-surface DMS enrichment to influence DMS emissions and also identify the factors influencing enrichment. DMS measurements in productive frontal waters over the Chatham Rise, east of New Zealand, did not identify any significant gradients between 0.01 and 6 m in sub-surface seawater, whereas DMS enrichment in the sea-surface microlayer was variable, with a mean enrichment factor (EF; the concentration ratio between DMS in the sea-surface microlayer and in sub-surface water) of 1.7. Physical and biological factors influenced sea-surface microlayer DMS concentration, with high enrichment (EF > 1.3) only recorded in a dinoflagellate-dominated bloom, and associated with low to medium wind speeds and near-surface temperature gradients. On occasion, high DMS enrichment preceded periods when the air-sea DMS flux, measured by eddy covariance, exceeded the flux calculated using National Oceanic and Atmospheric Administration (NOAA) Coupled-Ocean Atmospheric Response Experiment (COARE) parameterized gas transfer velocities and measured sub-surface seawater DMS concentrations. The results of these two independent approaches suggest that air-sea emissions may be influenced by near-surface DMS production under certain conditions, and highlight the need for further study to constrain the magnitude and mechanisms of DMS production in the sea-surface microlayer.

  13. Improvement of the GEOS-5 AGCM upon Updating the Air-Sea Roughness Parameterization

    NASA Technical Reports Server (NTRS)

    Garfinkel, C. I.; Molod, A.; Oman, L. D.; Song, I.-S.

    2011-01-01

    The impact of an air-sea roughness parameterization over the ocean that more closely matches recent observations of air-sea exchange is examined in the NASA Goddard Earth Observing System, version 5 (GEOS-5) atmospheric general circulation model. Surface wind biases in the GEOS-5 AGCM are decreased by up to 1.2m/s. The new parameterization also has implications aloft as improvements extend into the stratosphere. Many other GCMs (both for operational weather forecasting and climate) use a similar class of parameterization for their air-sea roughness scheme. We therefore expect that results from GEOS-5 are relevant to other models as well.

  14. Seasonal and Interannual fCO2 Variability in a Tropical Coastal Upwelling System

    NASA Astrophysics Data System (ADS)

    Astor, Y.; Scranton, M. I.; Muller-Karger, F. E.; Garcia, J.

    2004-12-01

    Monthly seawater pH and alkalinity measurements were collected between January 1996 and December 2000 at 10° 30' N and 64° 40' W as part of the CARIACO oceanographic time series (CArbon Retention In A Colored Ocean Program). The objective was to study temporal variability in Total CO2 (TCO2) concentrations and the CO2 fugacity (fCO2) at a tropical coastal wind-driven upwelling site. The difference between atmospheric and surface ocean CO2 concentrations (ÄfCO2) ranged from -64.3 to +62.3 µatm. Physical and biochemical factors, specifically upwelling, temperature, primary production, and TCO2 concentrations, interact to control temporal variation fCO2. Air-sea CO2 fluxes showed interannual variability. They were typically depressed (0 to +10 mmol C m-2 d-1) in the first few months of the year during the upwelling season and rose during June-November (+10 to 20 mmol C m-2 d-1). While fluxes were not related to changes in salinity, very low positive flux values were seen during the period of very heavy rains and land-derived runoff which depressed surface salinities during the second half of 1999. During the period examined, two events of negative air-sea CO2 flux were observed, namely in March 1997 (\\sim\\ -10 mmol C m-2 d-1) and in March 1998 (\\sim\\ 50 mmol C m-2 d-1), when extremely strong but short upwelling events occurred. Therefore, the Cariaco Basin generally acts as a source of CO2 to the atmosphere in spite of annual primary productivity in excess of between 300 and 600 gC m-2 y-1.

  15. Translucent CO2 ice on Mars ?

    NASA Astrophysics Data System (ADS)

    Schmidt, Frederic; Andrieu, Francois; Douté, Sylvain; Schmitt, Bernard

    2016-10-01

    The Martian climate is driven by the condensation/sublimation of CO2 representing 95% of the atmosphere. Many active surface features (such dark spot, dark flows), have been potentially linked to CO2 exchange. Understanding the surface/atmosphere interactions is a major issue, for both atmospheric but also surface science. This study aims at estimating the physical properties of the seasonal CO2 ice deposits. Are these deposits granular or compact? What is the thickness of the ice? How much impurities are included within the ice? These questions have been highly debated in the literature, in particular the presence of a translucent slab ice, the link with the H2O cycle. In particular the cold jet geyser model requires translucent CO2 ice. We use radiative transfer models to simulate spectroscopic data from the CRISM instrument and perform an inversion to estimate model's parameters though time. We then discuss the consistency of the results with other datasets.

  16. Air-Sea Interaction Measurements from R/P FLIP

    NASA Astrophysics Data System (ADS)

    Friehe, C. A.

    2002-12-01

    Soon after its inception, R/P FLIP was used to study the interaction of the atmosphere and ocean due to its unique stability and low flow distortion. A number of campaigns have been conducted to measure the surface fluxes of heat, water vapor and horizontal momentum of the wind with instrumentation as used over land, supported by the Office of Naval Research and the National Science Foundation. The size of FLIP allows for simultaneous ocean wave and mixed-layer measurements as well. Air-sea interaction was a prime component of BOMEX in 1968, where FLIP transited the Panama Canal. The methods used were similar to the over-land "Kansas" experiment of AFCRL in 1968. BOMEX was followed by many experiments in the north Pacific off San Diego, northern California, and Hawaii. Diverse results from FLIP include identification of the mechanism that causes erroneous fluctuating temperature measurements in the salt-aerosol-laden marine atmosphere, the role of humidity on optical refractive index fluctuations, and identification of Miles' critical layer in the air flow over waves.

  17. Unstable Air-Sea Interaction in the Extratropical North Atlantic

    NASA Technical Reports Server (NTRS)

    Hakkinen, Sirpa

    1999-01-01

    The possibility of coupled modes in the extratropical North Atlantic has fascinated the climate community since 1960's. A significant aspect of such modes is an unstable air-sea interaction, also called positive feedback, where disturbances between the atmosphere and ocean grow unbound. If a delayed response exists before the negative feedback takes effect, an oscillatory behaviour will develop. Here we explore the relationship between heat flux (positive upward) and sea surface temperature (SST). Positive feedback is characterized by a cross-correlation between the two where correlation maintains a negative sign whether SST or heat flux leads. We use model results and observations to argue that in the North Atlantic there exist regions with positive feedback. The two main locations coincide with the well-known north-south SST dipole where anomalies of opposite sign occupy areas east of Florida and north-east of Newfoundland. We show that oceanic dynamics, wave propagation and advection, give rise to oceanic anomalies in these regions. Subsequently these anomalies are amplified by atmosphere- ocean interaction: thus a positive feedback.

  18. CO2 laser preionisation

    NASA Technical Reports Server (NTRS)

    Spiers, Gary D.

    1991-01-01

    The final report for work done during the reporting period of January 25, 1990 to January 24, 1991 is presented. A literature survey was conducted to identify the required parameters for effective preionization in TEA CO2 lasers and the methods and techniques for characterizing preionizers are reviewed. A numerical model of the LP-140 cavity was used to determine the cause of the transverse mode stability improvement obtained when the cavity was lengthened. The measurement of the voltage and current discharge pulses on the LP-140 were obtained and their subsequent analysis resulted in an explanation for the low efficiency of the laser. An assortment of items relating to the development of high-voltage power supplies is also provided. A program for analyzing the frequency chirp data files obtained with the HP time and frequency analyzer is included. A program to calculate the theoretical LIMP chirp is also included and a comparison between experiment and theory is made. A program for calculating the CO2 linewidth and its dependence on gas composition and pressure is presented. The program also calculates the number of axial modes under the FWHM of the line for a given resonator length. A graphical plot of the results is plotted.

  19. Flash scanning the CO2 laser: a revival of the CO2 laser in plastic surgery

    NASA Astrophysics Data System (ADS)

    Lach, Elliot

    1994-09-01

    The CO2 laser has broad clinical application yet also presents a number of practical disadvantages. These drawbacks have limited the success and utilization of this laser in plastic surgery. Flashscanner technology has recently been used for char-free CO2 laser surgery of the oropharynx, the external female genital tract, and perirectal mucosa. A commercially available optomechanical flashscanner unit `Swiftlase,' was adapted to a CO2 laser and used for treatment in numerous plastic surgical applications. Conditions and situations that were treated in this study included generalized neurofibromatosis, tuberous sclerosis, rhinophyma, viral warts, breast reconstruction, and deepithelialization prior to microsurgery or local flap transfer and/or skin graft placement. There were no significant wound healing complications. Some patients previously sustained undue scarring from conventional CO2 laser surgery. Conservative, primarily ablative CO2 laser surgery with the Swiftlase has usefulness for treatment of patients in plastic surgery including those that were previously unsuccessfully treated.

  20. Overview of the CoOP experiments: Physical and chemical measurements parameterizing air-sea heat exchange

    NASA Astrophysics Data System (ADS)

    Bock, Erik John; Bearer Edson, James; Frew, Nelson M.; Hara, Tetsu; Haussecker, Horst; Jähne, Bernd; McGillis, Wade R.; McKenna, Sean P.; Nelson, Robert K.; Schimpf, Uwe; Uz, Mete

    Experiments performed in the Pacific and Atlantic Oceans in 1995 and 1997 attempted to measure the short time-scale and small spatial scale variability in the air-sea gas transfer rate. Along with these measurements, physical and chemical parameters known from previous laboratory studies to influence transfer rates were also characterized. These parameters include the atmospheric forcing, the capillary and capillary-gravity wave state, the surface chemical enrichment, and the level of near-surface turbulence. In this contribution we describe the methodologies employed for the measurement campaigns and summarize some general observations resulting from them. Other contributions from the coauthors describe in more detail the specific conclusions derived from the Coastal Ocean Processes (CoOP) field program.

  1. The influence of air-sea exchange on the isotropic composition of oceanic carbon: Observations and modeling

    SciTech Connect

    Lynch-Stieglitz, J.; Broecker, W.S.; Fairbanks, R.G.

    1995-12-01

    Although the carbon isotropic composition of ocean waters after they leave the surface ocean is determined by biological cycling, air-sea exchange affects the carbon isotopic composition of surface waters in two ways. The equilibrium fractionation between oceanic and atmospheric carbon increases with decreasing temperature. In Southern Ocean Surface Waters this isotopic equilibrium enriches {delta}{sup 13}C relative to the {delta}{sup 13}C expected from uptake and release of carbon by biological processes alone. Similarly, surface waters in the subtropical gyres are depleted in {delta}{sup 13}C due to extensive air-sea exchange at warm temperatures. Countering the tendency toward isotopic equilibration with the atmosphere (a relatively slow process), are the effects of the equilibration of CO{sub 2} itself (a much faster process). In regions where there is a net transfer of isotopically light CO{sub 2} from the ocean to the atmosphere (e.g., the equator) surface waters become enriched in {sup 13}C, whereas in regions where isotopically light CO{sub 2} is entering the ocean (e.g., the North Atlantic) surface waters become depleted in {sup 13}C. A compilation of high quality oceanic {delta}{sup 13}C measurements along with experiments performed using a zonally averaged three-basin dynamic ocean model are used to explore these processes. 40 refs., 14 figs., 1 tab.

  2. Air-Sea Exchange and Budget of Sulfur and Oxygen-Containing Volatile Organic Compounds in the Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Tanimoto, H.; Omori, Y.; Inomata, S.; Iwata, T.; Kameyama, S.

    2015-12-01

    By combining proton transfer reaction-mass spectrometry (PTR-MS) and gradient flux (GF) technique, in situ measurement of air-sea fluxes of multiple volatile organic compounds (VOCs) was developed and deployed. Starting in 2008, we made in situ observations of air-sea fluxes at 15 locations as well as underway observations of marine air/surface seawater bulk concentrations in the Pacific Ocean, during eight research cruises by R/V Hakuho-Maru. The fluxes of biogenic trace gases, DMS and isoprene, were always positive, with the magnitudes being in accordance with previously reported. In contrast, the fluxes of oxygenated VOCs including acetone and acetaldehyde varied from negative to positive, suggesting that the tropical and subtropical Pacific are a source, while the North Pacific is a sink. A basin-scale budget of VOCs were determined for 4 biogeochemical provinces in the Pacific Ocean, and the role of oceans for VOCs were discussed with respect to physical and biogeochemical processes.

  3. Air-Sea Interaction Studies of the Indian and Pacific Oceans

    DTIC Science & Technology

    2014-09-30

    tasks: Task 1: Air- Sea Interactions Impacting the North Arabian Sea Circulation Task 2: Satellite Observations of Flow Encountering Abrupt...resolution SAR data will allow monitoring of ocean processes in the North Arabian Sea circulation region due to current and/or meteorological forcing at a...1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Air- Sea Interaction Studies of the Indian and Pacific

  4. Atmospheric CO2 Removal by Enhancing Weathering

    NASA Astrophysics Data System (ADS)

    Koster van Groos, A. F.; Schuiling, R. D.

    2014-12-01

    The increase of the CO2 content in the atmosphere by the release of anthropogenic CO2 may be addressed by the enhancement of weathering at the surface of the earth. The average emission of mantle-derived CO2 through volcanism is ~0.3 Gt/year (109 ton/year). Considering the ~3.000 Gt of CO2 present in the atmosphere, the residence time of CO2 in the earth's atmosphere is ~10,000 years. Because the vast proportion of carbon in biomass is recycled through the atmosphere, CO2 is continuously removed by a series of weathering reactions of silicate minerals and stored in calcium and magnesium carbonates. The addition of anthropogenic CO2 from fossil fuel and cement production, which currently exceeds 35 Gt/year and dwarfs the natural production 100-fold, cannot be compensated by current rates of weathering, and atmospheric CO2 levels are rising rapidly. To address this increase in CO2 levels, weathering rates would have to be accelerated on a commensurate scale. Olivine ((Mg,Fe)2SiO4) is the most reactive silicate mineral in the weathering process. This mineral is the major constituent in relatively common ultramafic rocks such as dunites (olivine content > 90%). To consume the current total annual anthropogenic release of CO2, using a simplified weathering reaction (Mg2SiO4 + 4CO2 + 4H2O --> 2 Mg2+ + 4HCO3- + H4SiO4) would require ~30 Gt/year or ~8-9 km3/year of dunite. This is a large volume; it is about double the total amount of ore and gravel currently mined (~ 17 Gt/year). To mine and crush these rocks to <100 μm costs ~ 8/ton. The transport and distribution over the earth's surface involves additional costs, that may reach 2-5/ton. Thus, the cost of remediation for the release of anthropogenic CO2 is 300-400 billion/year. This compares to a 2014 global GDP of ~80 trillion. Because weathering reactions require the presence of water and proceed more rapidly at higher temperatures, the preferred environments to enhance weathering are the wet tropics. From a socio

  5. Shipboard Investigation of Air-sea Interaction and Cloud Processes in the VOCALS Stratocumulus Region

    NASA Astrophysics Data System (ADS)

    Fairall, C.; Kollias, P.; Zuidema, P.

    2005-12-01

    NOAA ETL, University of Miami, and Brookhaven National Laboratory have cooperated with the Woods Hole Oceanographic Institution (WHOI) for two research cruises to the stratocumulus region of Peru/Chile as part of NOAA's PACS/EPIC program. Ship-based measurements have taken in October of 2001, November 2003, and December 2004 at the WHOI ocean reference buoy at 20 S 85 W during the annual cruise to service the buoy. The goal of this work is to improve understanding of coupled air-sea processes in subtropical stratocumulus regions and to gather statistics on flux, boundary layer, and cloud properties to promote the evaluation of models and satellite data products. Specific scientific objectives involve improved bulk cloud-radiative parameterizations, methods for retrieving cloud microphysical properties, and investigation of the relative roles of cloud-top entrainment and drizzle production on the dynamics of stratocumulus. The measurements provide a more detailed context for measurements made on the WHOI buoy over the annual cycle. This will be achieved through: *Comprehensive characterization of clouds, surface fluxes, and PBL profiles using a variety of in situ and remote sensing systems *Evaluation of various bulk models of stratocumulus cloud radiative transfer properties using resulting cloud microphysics (integrated liquid water, drop size and number concentration) determined with ship-board remote sensors In this paper we will present the results from the three cruises emphasizing then diurnal cycle of cloud properties and comparing the seasonal differences.

  6. Effects of influent fractionation, kinetics, stoichiometry and mass transfer on CH4, H2 and CO2 production for (plant-wide) modeling of anaerobic digesters.

    PubMed

    Solon, Kimberly; Flores-Alsina, Xavier; Gernaey, Krist V; Jeppsson, Ulf

    2015-01-01

    This paper examines the importance of influent fractionation, kinetic, stoichiometric and mass transfer parameter uncertainties when modeling biogas production in wastewater treatment plants. The anaerobic digestion model no. 1 implemented in the plant-wide context provided by the benchmark simulation model no. 2 is used to quantify the generation of CH₄, H₂and CO₂. A comprehensive global sensitivity analysis based on (i) standardized regression coefficients (SRC) and (ii) Morris' screening's (MS's) elementary effects reveals the set of parameters that influence the biogas production uncertainty the most. This analysis is repeated for (i) different temperature regimes and (ii) different solids retention times (SRTs) in the anaerobic digester. Results show that both SRC and MS are good measures of sensitivity unless the anaerobic digester is operating at low SRT and mesophilic conditions. In the latter situation, and due to the intrinsic nonlinearities of the system, SRC fails in decomposing the variance of the model predictions (R² < 0.7) making MS a more reliable method. At high SRT, influent fractionations are the most influential parameters for predictions of CH₄and CO₂emissions. Nevertheless, when the anaerobic digester volume is decreased (for the same load), the role of acetate degraders gains more importance under mesophilic conditions, while lipids and fatty acid metabolism is more influential under thermophilic conditions. The paper ends with a critical discussion of the results and their implications during model calibration and validation exercises.

  7. CO2 Laser Market

    NASA Astrophysics Data System (ADS)

    Simonsson, Samuel

    1989-03-01

    It gives me a great deal of pleasure to introduce our final speaker of this morning's session for two reasons: First of all, his company has been very much in the news not only in our own community but in the pages of Wall Street Journal and in the world economic press. And, secondly, we would like to welcome him to our shores. He is a temporary resident of the United States, for a few months, forsaking his home in Germany to come here and help with the start up of a new company which we believe, probably, ranks #1 as the world supplier of CO2 lasers now, through the combination of former Spectra Physics Industrial Laser Division and Rofin-Sinar GMBH. Samuel Simonsson is the Chairman of the Board of Rofin-Sinar, Inc., here in the U.S. and managing director of Rofin-Sinar GMBH. It is a pleasure to welcome him.

  8. Rotational dependence of the proton-transfer reaction HBr+ + CO2 → HOCO+ + Br. II. Comparison of HBr+ (2Π(3/2)) and HBr+ (2Π(1/2)).

    PubMed

    Paetow, Lisa; Unger, Franziska; Beutel, Bernd; Weitzel, Karl-Michael

    2010-12-21

    The effects of reactant ion rotational excitation on the exothermic proton-transfer reactions of HBr(+)((2)Π(1/2)) and DBr(+)((2)Π(1/2)), respectively, with CO(2) were studied in a guided ion beam apparatus. Cross sections are presented for collision energies in the center of mass system E(c.m.) in the range of 0.23 to 1.90 eV. The HBr(+)/DBr(+) ions were prepared in a state-selective manner by resonance enhanced multiphoton ionization. The mean rotational energy was varied from 3.4 to 46.8 meV for HBr(+)((2)Π(1/2)) and from 1.8 to 40.9 meV for DBr(+)((2)Π(1/2)). Both reactions studied are inhibited by collision energy, as expected for exothermic reactions. For all collision energies considered, the cross section decreases with increasing rotational energy of the ion, but the degree of the rotational dependence differs depending on the collision energy. For E(c.m.) = 0.31 eV, the cross sections of the deuteron transfer are significantly larger than those of the proton transfer. For higher E(c.m.) they differ very little. The current results for the exothermic proton transfer are systematically compared to previously published data for the endothermic proton transfer starting from HBr(+)((2)Π(3/2)) [L. Paetow et al., J. Chem. Phys. 132, 174305 (2010)]. Additional new data regarding the latter reaction are presented to further confirm the conclusions. The dependences on rotational excitation found cannot be explained by the corresponding change in the total energy of the system. For both the endothermic and the exothermic reaction, the cross section is maximized for the smallest rotational energy, at least well above the threshold.

  9. Short-term natural δ13C and δ18O variations in pools and fluxes in a beech forest: the transfer of isotopic signal from recent photosynthates to soil respired CO2

    NASA Astrophysics Data System (ADS)

    Gavrichkova, O.; Proietti, S.; Moscatello, S.; Portarena, S.; Battistelli, A.; Matteucci, G.; Brugnoli, E.

    2011-10-01

    The fate of photosynthetic products within the plant-soil continuum determines how long the reduced carbon resides within the ecosystem and when it returns back to the atmosphere in the form of respiratory CO2. We have tested the possibility of measuring natural variation in δ13C and δ18O to disentangle the potential times needed to transfer carbohydrates produced by photosynthesis down to trunk, roots and, in general, to belowground up to its further release in the form of soil respiration into the atmosphere in a beech (Fagus sylvatica) forest. We have measured the variation in stable carbon and oxygen isotope compositions in plant material and in soil respired CO2 every three hours for three consecutive days. Possible steps and different signs of post-photosynthetic fractionation during carbon translocation were also identified. A 12 h-periodicity was observed for variation in δ13C in soluble sugars in the top crown leaves and it can be explained by starch day/night dynamics in synthesis and breakdown and by stomatal limitations under elevated vapour pressure deficits. Photosynthetic products were transported down the trunk and mixed with older carbon pools, therefore causing the dampening of the δ13C signal variation. The strongest periodicity of 24 h was found in δ13C in soil respiration indicating changes in root contribution to the total CO2 efflux. Other non-biological causes like diffusion fractionation and advection induced by gas withdrawn from the measurement chamber complicate data interpretation on this step of C transfer path. Nevertheless, it was possible to identify the speed of carbohydrates' translocation from the point of assimilation to the trunk breast height because leaf-imprinted enrichment of δ18O in soluble sugars was less modified along the downward transport and was well related to environmental parameters potentially linked to stomatal conductance. The speed of carbohydrates translocation from the site of assimilation to the trunk

  10. The impact on atmospheric CO2 of iron fertilization induced changes in the ocean's biological pump

    NASA Astrophysics Data System (ADS)

    Jin, X.; Gruber, N.; Frenzel, H.; Doney, S. C.; McWilliams, J. C.

    2007-10-01

    Using numerical simulations, we quantify the impact of changes in the ocean's biological pump on the air-sea balance of CO2 by fertilizing a small surface patch in the high-nutrient, low-chlorophyll region of the eastern tropical Pacific with iron. Decade-long fertilization experiments are conducted in a basin-scale, eddy-permitting coupled physical biogeochemical ecological model. In contrast to previous studies, we find that most of the dissolved inorganic carbon (DIC) removed from the euphotic zone by the enhanced biological export is replaced by uptake of CO2 from the atmosphere. Atmospheric uptake efficiencies, the ratio of the perturbation in air-sea CO2 flux to the perturbation in export flux across 100 m, are 0.75 to 0.93 in our patch size-scale experiments. The atmospheric uptake efficiency is insensitive to the duration of the experiment. The primary factor controlling the atmospheric uptake efficiency is the vertical distribution of the enhanced biological production. Iron fertilization at the surface tends to induce production anomalies primarily near the surface, leading to high efficiencies. In contrast, mechanisms that induce deep production anomalies (e.g. altered light availability) tend to have a low uptake efficiency, since most of the removed DIC is replaced by lateral and vertical transport and mixing. Despite high atmospheric uptake efficiencies, patch-scale iron fertilization of the ocean's biological pump tends to remove little CO2 from the atmosphere over the decadal timescale considered here.

  11. Simulation and Observation of Global Atmospheric CO2 from 2009-2010

    NASA Astrophysics Data System (ADS)

    Denning, A.; O'Dell, C. W.; Baker, D. F.; Parazoo, N.; McKeown, R.; Baker, I. T.; Kawa, S. R.; Doney, S. C.

    2011-12-01

    We compare global variations in atmospheric CO2 concentrations using a comprehensive model of surface carbon cycling and atmospheric transport to retrievals of column CO2 mole fraction from near-infrared spectroscopy from the GOSAT mission. Surface carbon exchanges due to photosynthesis, respiration, decomposition, biomass burning, fossil fuel combustion, and air-sea gas exchange are computed every hour. These fluxes are used as input to a global atmospheric tranport model to obtain three-dimensional fields of CO2, which are sampled at the time and location of quality-screened GOSAT data retrieved by the Atmospheric Carbon Observations from Space (ACOS) team. The system is operated on a 0.5° x 0.67° grid (dx ~ 50 km), providing global mesoscale coverage, and has good skill at replicating diurnal, synoptic, and seasonal variations over vegetated land surfaces. It is driven by meteorological output from the NASA Goddard EOS Data Assimilation System. Surface weather from the system drives calculations of terrestrial ecosystem metabolism (radiation, precipitation, humidity, temperature) and air-sea gas exchange (wind), with other input data coming from satellite data products. Simulated spatial patterns and seasonal variations of simulated and observed column CO2 exhibit broad agreement, but some offsets in latitude and seasonal variations are noted. These are attributed to both model and satellite retrieval errors.

  12. Comparison of CO2 fluxes estimated using atmospheric and oceanic inversions, and role of fluxes and their interannual variability in simulating atmospheric CO2 concentrations

    NASA Astrophysics Data System (ADS)

    Patra, P. K.; Mikaloff Fletcher, S. E.; Ishijima, K.; Maksyutov, S.; Nakazawa, T.

    2006-07-01

    We use a time-dependent inverse (TDI) model to estimate regional sources and sinks of atmospheric CO2 from 64 and then 22 regions based on atmospheric CO2 observations at 87 stations. The air-sea fluxes from the 64-region atmospheric-CO2 inversion are compared with fluxes from an analogous ocean inversion that uses ocean interior observations of dissolved inorganic carbon (DIC) and other tracers and an ocean general circulation model (OGCM). We find that, unlike previous atmospheric inversions, our flux estimates in the southern hemisphere are generally in good agreement with the results from the ocean inversion, which gives us added confidence in our flux estimates. In addition, a forward tracer transport model (TTM) is used to simulate the observed CO2 concentrations using (1) estimates of fossil fuel emissions and a priori estimates of the terrestrial and oceanic fluxes of CO2, and (2) two sets of TDI model corrected fluxes. The TTM simulations of TDI model corrected fluxes show improvements in fitting the observed interannual variability in growth rates and seasonal cycles in atmospheric CO2. Our analysis suggests that the use of interannually varying (IAV) meteorology and a larger observational network have helped to capture the regional representation and interannual variabilities in CO2 fluxes realistically.

  13. A comprehensive carbon dioxide analysis system for estimating CO2 emissions

    NASA Astrophysics Data System (ADS)

    Denning, A.; Parazoo, N.; Lokupitiya, R. S.; Baker, D. F.

    2010-12-01

    Greenhouse gas emissions due to combustion of fossil fuel can be estimated from observations of variations in atmospheric trace gases in time and space. Quantitative interpretation of these variations requires accounting for stronger changes due to other processes such as ecosystem metabolism, biomass burning, and air-sea gas exchange that operate on global scales. We have developed and tested an analysis system for assimilation of CO2 variations measured by a combination of sampling, in-situ, and remotely-sensed observations. The system combines existing models of CO2 exchanges due to hourly photosynthesis and respiration, daily air-sea gas exchange, biomass burning, fossil fuel emissions, and atmospheric transport. This comprehensive system allows direct comparison to the observed record of both in-situ and remotely sensed atmospheric CO2 at hourly timescales. By design, we decompose surface fluxes of CO2 into the atmosphere into “fast processes” that are well-understood and modeled using mechanistic algorithms, and more slowly-varying fluxes due to land use change, incorrect specification of decomposing carbon pools, and other persistent biases in the forward component models. These slowly varying components are then estimated from atmospheric obervations by the Maximum Likelihood Ensembe Filter, a data assimilation framework. The system is operated on a 0.5° x 0.67° grid, providing global mesoscale coverage, and has good skill at replicating diurnal, synoptic, and seasonal variations over vegetated land surfaces. It is driven by meteorological output from the NASA Goddard EOS Data Assimilation System. Surface weather from the system drives calculations of terrestrial ecosystem metabolism (radiation, precipitation, humidity, temperature) and air-sea gas exchange (wind), with other input data coming from satellite data products.

  14. CO2-Leaking Well - Analytical Modeling

    NASA Astrophysics Data System (ADS)

    Wertz, F.; Audigane, P.; Bouc, O.

    2009-04-01

    the literature - are combined with a prior study of CO2 thermodynamic properties over pressure and temperature conditions at typical geological depths. Different kinds of assumptions can be used in this model: - CO2 rises along a hydrostatic profile of pressure and temperature if we consider that energy exchanges are small and fast enough at every depth. - CO2 rises along an isenthalpic profile of pressure and temperature if on the contrary we consider that the CO2 does not exchange energy (any more) with surrounding water. - CO2 stays in a bubble flow or not, with transition or not. Besides intrinsic results such as flow rate, speed and state of the CO2 along the water column - that could be a badly cemented well, a water-filled fault, or any other extent where water is free - it can be used as a tool for other more developed scenarios (vertical transfer between 2 aquifers, etc.). Preliminary interesting results concern the transition phase of the fluid that arises at about 800m. Indeed, at such critical depth and according to the gas specific enthalpy, CO2 bubbles may expand a lot and accelerate, or on the contrary condensate into liquid phase and slow down.

  15. Experimental investigation of CO2 condensation process using cryogen

    NASA Astrophysics Data System (ADS)

    Lee, Cheonkyu; Yoo, Junghyun; Lee, Jisung; Park, Hana; Jeong, Sangkwon

    2014-01-01

    Carbon dioxide (CO2) is one of the dominant gas molecules that causes greenhouse effect, i.e. global warming. Numerous studies have been carried out to regulate the emission of CO2 to reduce greenhouse gas. The liquid CO2 is a convenient form of transportation compared to high-pressurized gaseous CO2. Therefore, the direct liquefaction mechanism of CO2 at low temperature draws technical attention recently. In particular, cold thermal energy of Liquefied Natural Gas (LNG) could be a candidate to condense gaseous CO2, especially in the LNG powered ship. In this paper, the detailed direct condensation process of CO2 using LN2 with intermittent solidification is investigated. Pressurized CO2 at 600 kPa is directly liquefied in a vessel by liquid nitrogen which is supplied into the coiled tube heat exchanger inside the CO2 vessel. The heat exchanger temperature is controlled from 130 K to 205 K to regulate the solidification and sublimation of CO2 by duty control with cryogenic solenoid valve. The characteristics of CO2 condensation process with cryogen are analyzed from the measurement results. The results show that the solidification causes the significant degradation of CO2 condensation heat transfer. Finally, the condensation rate with and without solidification is compared.

  16. Did the North Atlantic Ocean sequester more CO2 during the last glacial?

    NASA Astrophysics Data System (ADS)

    Yu, J.; Thornalley, D. J.; Jin, Z.; Rohling, E. J.; Menviel, L.; McCave, I. N. N.

    2015-12-01

    To explain the ~90 ppm lower atmospheric CO2 content during the Last Glacial Maximum, much effort has been focused on the mechanisms that helped to limit the outgassing of CO2 from the deep ocean to the atmosphere via the Southern Ocean. Field measurements and modeling studies suggest that the North Atlantic Ocean has been an important sink of CO2 during preindustrial and modern times. However, the role of the North Atlantic in sequestering atmospheric CO2 in the past largely remains unconstrained. Here, we use a suite of geochemical proxies to reconstruct nutrient and carbonate ion concentrations of both surface and deep waters in the North Atlantic during the last ~25 kyr. When normalized to the same nutrient levels, we find that the gradient in carbonate ion content between surface and mid-depth waters increased during the last glacial. Although a combination of factors including changes in Redfield ratio and rain ratio and increased CO2 absorption at the air-sea boundary might have caused the observed change, the greater gradient most likely suggests an enhanced sequestration of CO2 in the North Atlantic Ocean during the Last Glacial Maximum. Therefore, we infer that, in addition to changes in the Southern Ocean, processes in the North Atlantic Ocean enhanced the uptake of CO2 and synergistically contributed to the low atmospheric CO2 during ice ages.

  17. Forecasting global atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Agustí-Panareda, A.; Massart, S.; Chevallier, F.; Boussetta, S.; Balsamo, G.; Beljaars, A.; Ciais, P.; Deutscher, N. M.; Engelen, R.; Jones, L.; Kivi, R.; Paris, J.-D.; Peuch, V.-H.; Sherlock, V.; Vermeulen, A. T.; Wennberg, P. O.; Wunch, D.

    2014-11-01

    A new global atmospheric carbon dioxide (CO2) real-time forecast is now available as part of the pre-operational Monitoring of Atmospheric Composition and Climate - Interim Implementation (MACC-II) service using the infrastructure of the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting System (IFS). One of the strengths of the CO2 forecasting system is that the land surface, including vegetation CO2 fluxes, is modelled online within the IFS. Other CO2 fluxes are prescribed from inventories and from off-line statistical and physical models. The CO2 forecast also benefits from the transport modelling from a state-of-the-art numerical weather prediction (NWP) system initialized daily with a wealth of meteorological observations. This paper describes the capability of the forecast in modelling the variability of CO2 on different temporal and spatial scales compared to observations. The modulation of the amplitude of the CO2 diurnal cycle by near-surface winds and boundary layer height is generally well represented in the forecast. The CO2 forecast also has high skill in simulating day-to-day synoptic variability. In the atmospheric boundary layer, this skill is significantly enhanced by modelling the day-to-day variability of the CO2 fluxes from vegetation compared to using equivalent monthly mean fluxes with a diurnal cycle. However, biases in the modelled CO2 fluxes also lead to accumulating errors in the CO2 forecast. These biases vary with season with an underestimation of the amplitude of the seasonal cycle both for the CO2 fluxes compared to total optimized fluxes and the atmospheric CO2 compared to observations. The largest biases in the atmospheric CO2 forecast are found in spring, corresponding to the onset of the growing season in the Northern Hemisphere. In the future, the forecast will be re-initialized regularly with atmospheric CO2 analyses based on the assimilation of CO2 products retrieved from satellite measurements and

  18. Using Wind Setdown and Storm Surge on Lake Erie to Calibrate the Air-Sea Drag Coefficient

    PubMed Central

    Drews, Carl

    2013-01-01

    The air-sea drag coefficient controls the transfer of momentum from wind to water. In modeling storm surge, this coefficient is a crucial parameter for estimating the surge height. This study uses two strong wind events on Lake Erie to calibrate the drag coefficient using the Coupled Ocean Atmosphere Wave Sediment Transport (COAWST) modeling system and the the Regional Ocean Modeling System (ROMS). Simulated waves are generated on the lake with Simulating WAves Nearshore (SWAN). Wind setdown provides the opportunity to eliminate wave setup as a contributing factor, since waves are minimal at the upwind shore. The study finds that model results significantly underestimate wind setdown and storm surge when a typical open-ocean formulation without waves is used for the drag coefficient. The contribution of waves to wind setdown and storm surge is 34.7%. Scattered lake ice also increases the effective drag coefficient by a factor of 1.1. PMID:23977309

  19. Using wind setdown and storm surge on Lake Erie to calibrate the air-sea drag coefficient.

    PubMed

    Drews, Carl

    2013-01-01

    The air-sea drag coefficient controls the transfer of momentum from wind to water. In modeling storm surge, this coefficient is a crucial parameter for estimating the surge height. This study uses two strong wind events on Lake Erie to calibrate the drag coefficient using the Coupled Ocean Atmosphere Wave Sediment Transport (COAWST) modeling system and the the Regional Ocean Modeling System (ROMS). Simulated waves are generated on the lake with Simulating WAves Nearshore (SWAN). Wind setdown provides the opportunity to eliminate wave setup as a contributing factor, since waves are minimal at the upwind shore. The study finds that model results significantly underestimate wind setdown and storm surge when a typical open-ocean formulation without waves is used for the drag coefficient. The contribution of waves to wind setdown and storm surge is 34.7%. Scattered lake ice also increases the effective drag coefficient by a factor of 1.1.

  20. Forecasting global atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Agustí-Panareda, A.; Massart, S.; Chevallier, F.; Boussetta, S.; Balsamo, G.; Beljaars, A.; Ciais, P.; Deutscher, N. M.; Engelen, R.; Jones, L.; Kivi, R.; Paris, J.-D.; Peuch, V.-H.; Sherlock, V.; Vermeulen, A. T.; Wennberg, P. O.; Wunch, D.

    2014-05-01

    A new global atmospheric carbon dioxide (CO2) real-time forecast is now available as part of the pre-operational Monitoring of Atmospheric Composition and Climate - Interim Implementation (MACC-II) service using the infrastructure of the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting System (IFS). One of the strengths of the CO2 forecasting system is that the land surface, including vegetation CO2 fluxes, is modelled online within the IFS. Other CO2 fluxes are prescribed from inventories and from off-line statistical and physical models. The CO2 forecast also benefits from the transport modelling from a state-of-the-art numerical weather prediction (NWP) system initialized daily with a wealth of meteorological observations. This paper describes the capability of the forecast in modelling the variability of CO2 on different temporal and spatial scales compared to observations. The modulation of the amplitude of the CO2 diurnal cycle by near-surface winds and boundary layer height is generally well represented in the forecast. The CO2 forecast also has high skill in simulating day-to-day synoptic variability. In the atmospheric boundary layer, this skill is significantly enhanced by modelling the day-to-day variability of the CO2 fluxes from vegetation compared to using equivalent monthly mean fluxes with a diurnal cycle. However, biases in the modelled CO2 fluxes also lead to accumulating errors in the CO2 forecast. These biases vary with season with an underestimation of the amplitude of the seasonal cycle both for the CO2 fluxes compared to total optimized fluxes and the atmospheric CO2 compared to observations. The largest biases in the atmospheric CO2 forecast are found in spring, corresponding to the onset of the growing season in the Northern Hemisphere. In the future, the forecast will be re-initialized regularly with atmospheric CO2 analyses based on the assimilation of CO2 satellite retrievals, as they become available in

  1. Common freshwater cyanobacteria grow in 100% CO2.

    PubMed

    Thomas, David J; Sullivan, Shannon L; Price, Amanda L; Zimmerman, Shawn M

    2005-02-01

    Cyanobacteria and similar organisms produced most of the oxygen found in Earth's atmosphere, which implies that early photosynthetic organisms would have lived in an atmosphere that was rich in CO2 and poor in O2. We investigated the tolerance of several cyanobacteria to very high (>20 kPa) concentrations of atmospheric CO2. Cultures of Synechococcus PCC7942, Synechocystis PCC7942, Plectonema boryanum, and Anabaena sp. were grown in liquid culture sparged with CO2-enriched air. All four strains grew when transferred from ambient CO2 to 20 kPa partial pressure of CO2 (pCO2), but none of them tolerated direct transfer to 40 kPa pCO2. Synechococcus and Anabaena survived 101 kPa (100%) pCO2 when pressure was gradually increased by 15 kPa per day, and Plectonema actively grew under these conditions. All four strains grew in an anoxic atmosphere of 5 kPa pCO2 in N2. Strains that were sensitive to high CO2 were also sensitive to low initial pH (pH 5-6). However, low pH in itself was not sufficient to prevent growth. Although mechanisms of damage and survival are still under investigation, we have shown that modern cyanobacteria can survive under Earth's primordial conditions and that cyanobacteria-like organisms could have flourished under conditions on early Mars, which probably had an atmosphere similar to early Earth's.

  2. Is CO2 ice permanent?

    NASA Technical Reports Server (NTRS)

    Lindner, Bernhard Lee

    1992-01-01

    Carbon dioxide ice has been inferred to exist at the south pole in summertime, but Earth based measurements in 1969 of water vapor in the Martian atmosphere suggest that all CO2 ice sublined from the southern polar cap and exposed underlying water ice. This implies that the observed summertime CO2 ice is of recent origin. It appears possible to construct an energy balance model that maintains seasonal CO2 ice at the south pole year round and still reasonably simulates the polar cap regression and atmospheric pressure data. This implies that the CO2 ice observed in the summertime south polar cap could be seasonal in origin, and that minor changes in climate could cause CO2 ice to completely vanish, as would appear to have happened in 1969. However, further research remains before it is certain whether the CO2 ice observed in the summertime south polar cap is seasonal or is part of a permanent reservoir.

  3. Co2 geological sequestration

    SciTech Connect

    Xu, Tianfu

    2004-11-18

    Human activities are increasingly altering the Earth's climate. A particular concern is that atmospheric concentrations of carbon dioxide (CO{sub 2}) may be rising fast because of increased industrialization. CO{sub 2} is a so-called ''greenhouse gas'' that traps infrared radiation and may contribute to global warming. Scientists project that greenhouse gases such as CO{sub 2} will make the arctic warmer, which would melt glaciers and raise sea levels. Evidence suggests that climate change may already have begun to affect ecosystems and wildlife around the world. Some animal species are moving from one habitat to another to adapt to warmer temperatures. Future warming is likely to exceed the ability of many species to migrate or adjust. Human production of CO{sub 2} from fossil fuels (such as at coal-fired power plants) is not likely to slow down soon. It is urgent to find somewhere besides the atmosphere to put these increased levels of CO{sub 2}. Sequestration in the ocean and in soils and forests are possibilities, but another option, sequestration in geological formations, may also be an important solution. Such formations could include depleted oil and gas reservoirs, unmineable coal seams, and deep saline aquifers. In many cases, injection of CO2 into a geological formation can enhance the recovery of hydrocarbons, providing value-added byproducts that can offset the cost of CO{sub 2} capture and sequestration. Before CO{sub 2} gas can be sequestered from power plants and other point sources, it must be captured. CO{sub 2} is also routinely separated and captured as a by-product from industrial processes such as synthetic ammonia production, H{sub 2} production, and limestone calcination. Then CO{sub 2} must be compressed into liquid form and transported to the geological sequestration site. Many power plants and other large emitters of CO{sub 2} are located near geological formations that are amenable to CO{sub 2} sequestration.

  4. Wintertime air-sea interaction processes across the Gulf Stream

    NASA Astrophysics Data System (ADS)

    Bane, John M.; Osgood, Kenric E.

    1989-08-01

    Aircraft, buoy and satellite measurements have been used to study the wintertime air-sea interaction processes across the Gulf Stream during January 25-30, 1986. The turbulent flux regime in the marine atmospheric boundary layer exhibited considerable spatial and temporal variability during this 6-day period, which was related to both the evolution of the synoptic scale atmospheric conditions and the sea surface temperature (SST) field. During the pre-storm conditions prior to January 25, the spatial structure of the SST field played an important role in generating a shallow atmospheric frontal zone along the Gulf Stream front by causing differential heating of the marine atmospheric boundary layer over the stream versus over the cooler shelf waters. As this front moved shoreward on January 25, the warm, moist, maritime air flowing northwestward behind the front induced moderate ocean-to-atmosphere heat fluxes (˜300 W m-2 total heat flux measured over the core of the Gulf Stream). The subsequent outbreak of eastward flowing cold, dry, continental air over the ocean on January 27 and 28 generated high total heat fluxes (˜1060 W m-2 over the core of the Stream), as did a second, somewhat weaker outbreak which followed on January 30 (˜680 W2 over the core of the Stream). During each of these outbreaks, with air flowing from land out over the continental shelf, Gulf Stream and Sargasso Sea waters, the SST field again affected the spatial structure of the flux fields. The near-surface fluxes of both sensible and latent heat were found to be relatively low over the cool continental shelf waters, while higher fluxes were seen over the Gulf Stream and Sargasso Sea. Similar spatial structure was seen in the near-surface momentum flux values, but relative changes were typically smaller from one location to another on a particular day. The most noticeable responses of the Gulf Stream to these surface fluxes were the deepening of its mixed layer and a loss of upper layer

  5. Air-sea interactions a techno-political history and future challenges

    NASA Astrophysics Data System (ADS)

    Geernaert, G.

    2003-04-01

    Air-sea interaction research has its origins in early inquiry into wave suppression and fisheries. These led to efforts designed to model current systems, predict risks and threats to commercial and exploit fisheries for economic benefit. A new set of national goals emerged about a century ago: exploit the physics of air-sea interactions for military superiority; to be followed a half century later with efforts to understand air-sea interactions to address water quality, offshore energy and climate challenges. In most part, sociopolitical events precipitated new scientific discoveries, through agency financed networks and targeted research programs. There are also examples of science driving the agency process. In this presentation, a brief history of political and scientific challenges will be given, to be followed by a summary of our greatest upcoming challenges.

  6. An improved method for detecting anthropogenic CO2 in the oceans

    NASA Astrophysics Data System (ADS)

    Gruber, Nicolas; Sarmiento, Jorge L.; Stocker, Thomas F.

    1996-12-01

    An improved method has been developed for the separation of the anthropogenic CO2 from the large natural background variability of dissolved inorganic carbon (C) in the ocean. This technique employs a new quasi-conservative carbon tracer ΔC*, which reflects the uptake of anthropogenic CO2 and the air-sea disequilibrium when a water parcel loses contact with the atmosphere. The air-sea disequilibrium component can be discriminated from the anthropogenic signal using either information about the water age or the distribution of ΔC* in regions not affected by the anthropogenic transient. This technique has been applied to data from the North Atlantic sampled during the Transient Tracers in the Ocean North Atlantic (TTO NAS) and Tropical Atlantic study (TTO TAS) cruises in 1981-1983. The highest anthropogenic CO2 concentrations and specific inventories (inventory per square meter) are found in the subtropical convergence zone. In the North Atlantic, anthropogenic CO2 has already invaded deeply into the interior of the ocean, north of 50°N it has even reached the bottom. Only waters below 3000 m and south of 30°N are not yet affected. We estimate an anthropogenic CO2 inventory of 20 ± 4 Gt C in the North Atlantic between 10°N and 80°N. The 2.5-dimensional ocean circulation model of Stocker et al. [1994] and the three-dimensional ocean general circulation biogeochemistry model of Sarmiento et al. [1995] predict anthropogenic CO2 inventories of 18.7 Gt C and 18.4 Gt C, respectively, in good agreement with the observed inventory. Important differences exist on a more regional scale, associated with known deficiencies of the models.

  7. CO2 interaction with geomaterials.

    SciTech Connect

    Guthrie, George D.; Al-Saidi, Wissam A.; Jordan, Kenneth D.; Voora, Vamsee, K.; Romanov, Vyacheslav N.; Lopano, Christina L; Myshakin, Eugene M.; Hur, Tae Bong; Warzinski, Robert P.; Lynn, Ronald J.; Howard, Bret H.; Cygan, Randall Timothy

    2010-09-01

    This work compares the sorption and swelling processes associated with CO2-coal and CO2-clay interactions. We investigated the mechanisms of interaction related to CO2 adsortion in micropores, intercalation into sub-micropores, dissolution in solid matrix, the role of water, and the associated changes in reservoir permeability, for applications in CO2 sequestration and enhanced coal bed methane recovery. The structural changes caused by CO2 have been investigated. A high-pressure micro-dilatometer was equipped to investigate the effect of CO2 pressure on the thermoplastic properties of coal. Using an identical dilatometer, Rashid Khan (1985) performed experiments with CO2 that revealed a dramatic reduction in the softening temperature of coal when exposed to high-pressure CO2. A set of experiments was designed for -20+45-mesh samples of Argonne Premium Pocahontas No.3 coal, which is similar in proximate and ultimate analysis to the Lower Kittanning seam coal that Khan used in his experiments. No dramatic decrease in coal softening temperature has been observed in high-pressure CO2 that would corroborate the prior work of Khan. Thus, conventional polymer (or 'geopolymer') theories may not be directly applicable to CO2 interaction with coals. Clays are similar to coals in that they represent abundant geomaterials with well-developed microporous structure. We evaluated the CO2 sequestration potential of clays relative to coals and investigated the factors that affect the sorption capacity, rates, and permanence of CO2 trapping. For the geomaterials comparison studies, we used source clay samples from The Clay Minerals Society. Preliminary results showed that expandable clays have CO2 sorption capacities comparable to those of coal. We analyzed sorption isotherms, XRD, DRIFTS (infrared reflectance spectra at non-ambient conditions), and TGA-MS (thermal gravimetric analysis) data to compare the effects of various factors on CO2 trapping. In montmorillonite, CO2

  8. Continuous CO2 extractor and methods

    SciTech Connect

    None listed

    2010-06-15

    The purpose of this CRADA was to assist in technology transfer from Russia to the US and assist in development of the technology improvements and applications for use in the U.S. and worldwide. Over the period of this work, ORNL has facilitated design, development and demonstration of a low-pressure liquid extractor and development of initial design for high-pressure supercritical CO2 fluid extractor.

  9. Leaves: Elevated CO2 levels

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Burning fossil fuels and land use changes such as deforestation and urbanization have led to a dramatic rise in the concentration of carbon dioxide (CO2) in the atmosphere since the onset of the Industrial Revolution. The highly dilute CO2 from the atmosphere enters plant leaves where it is concentr...

  10. Monitoring of near surface CO2

    NASA Astrophysics Data System (ADS)

    Faber, E.; Möller, I.; Teschner, M.; Poggenburg, J.; Spickenbom, K.; Schulz, H. J.

    2009-04-01

    Monitoring of near surface CO2 ECKHARD FABER1, INGO MÖLLER1, MANFRED TESCHNER1, JÜRGEN POGGENBURG1, KAI SPICKENBOM1, HANS-MARTIN SCHULZ1,2 1Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), Stilleweg 2, D-30655 Hannover, e.faber@bgr.de 2present adress: GeoForschungsZentrum Potsdam (GFZ), Telegrafenberg, D-14473 Potsdam Underground gas storage and sequestration of carbon dioxide is one of the methods to reduce the input of antropogenic CO2 into the atmosphere and its greenhouse effect. Storage of CO2 is planned in depleted reservoirs, in aquifers and in salt caverns. Storage sites must have very small leakage rates to safely store the CO2 for centuries. Thus, a careful investigation and site selection is crucial. However, any leakage of CO2 to the surface is potentially dangerous for humans and environment. Therefore, instruments and systems for the detection of any CO2 escaping the storage sites and reaching the atmosphere have to be developed. Systems to monitor gases in deep wells, groundwater and surface sediments for leaking CO2 are developed, tested and are contnuously improved. Our group is mainly analysing CO2 in shallow (down to 3 m) soil samples using automatically operating monitoring systems. The systems are equipped with sensors to measure CO2 (and other gases) concentrations and other environmental parameters (atmospheric pressure, ambient and soil temperatures, etc.). Data are measured in short intervals (minute to subminute), are stored locally and are transferred by telemetrical systems into the BGR laboratory (Weinlich et al., 2006). In addition to soil gases monitoring systems technical equipment is available for continuous underwater gas flow measurements. Several of those monitoring systems are installed in different areas like Czech Republic, Austria, Italy and Germany. To detect any leaking gas from a sequestration site after CO2 injection, the naturally existing CO2 concentration (before injection) must be known. Thus, the natural

  11. Implications of a Changing Arctic on Summertime Surface Seawater pCO2 Variations in the Eastern Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Burgers, T.; Miller, L. A.; Thomas, H.; Else, B. G. T.; Gosselin, M.; Papakyriakou, T. N.

    2015-12-01

    Arctic marine carbonate chemistry and rates of air-sea CO2 exchange are anticipated to be affected by current changes in sea-ice structure and extent, freshwater inputs, ocean circulation patterns, and the seasonality of phytoplankton blooms. This study examines how such changes will impact rates of air-sea CO2 exchange in northern Baffin Bay, Nares Strait, and the eastern Canadian Arctic Archipelago. This complex oceanographic region includes the North Water polynya; one of the most biologically productive areas in the Arctic Ocean, and the convergence site of the warm West Greenland Current with cold exported Arctic waters. Continuous measurements of atmospheric and surface seawater CO2 (pCO2) were collected onboard the Canadian Coast Guard Ship Amundsen during its 2013 and 2014 summer cruises. Surface seawater pCO2 displayed considerable variability (145 - 389 ppm), but never exceeded atmospheric concentrations. Calculated CO2 fluxes ranged from 0 to -45 mmol m-2 day-1 (oceanic uptake), and were estimated using the Sweeney et al. (2007) parameterization with in-situ wind speed measurements. Ancillary measurements of chlorophyll a reveal low productivity in surface waters during mid-summer with isolated sub-surface blooms. This is likely the result of nutrient limitation within the highly stratified polar mixed layer (PML). Measurements of stable oxygen isotope ratios (δ18O) and total alkalinity were used to estimate freshwater inputs (sea-ice melt vs. meteoric water) to the PML. These and in-situ observations of sea ice cover were used to interpret seawater pCO2 variations. Surface waters influenced by sea-ice melt exhibit lower pCO2 than those influenced by meteoric water. The results of this investigation shed light on the future role of this region as a summertime sink of atmospheric CO2.

  12. CO2 Sequestration short course

    SciTech Connect

    DePaolo, Donald J.; Cole, David R; Navrotsky, Alexandra; Bourg, Ian C

    2014-12-08

    Given the public’s interest and concern over the impact of atmospheric greenhouse gases (GHGs) on global warming and related climate change patterns, the course is a timely discussion of the underlying geochemical and mineralogical processes associated with gas-water-mineral-interactions encountered during geological sequestration of CO2. The geochemical and mineralogical processes encountered in the subsurface during storage of CO2 will play an important role in facilitating the isolation of anthropogenic CO2 in the subsurface for thousands of years, thus moderating rapid increases in concentrations of atmospheric CO2 and mitigating global warming. Successful implementation of a variety of geological sequestration scenarios will be dependent on our ability to accurately predict, monitor and verify the behavior of CO2 in the subsurface. The course was proposed to and accepted by the Mineralogical Society of America (MSA) and The Geochemical Society (GS).

  13. Air sea gas exchange at extreme wind speeds measured by autonomous oceanographic floats

    NASA Astrophysics Data System (ADS)

    D'Asaro, Eric; McNeil, Craig

    2007-06-01

    Measurements of the air-sea fluxes of N 2 and O 2 were made in winds of 15-57 m s - 1 beneath Hurricane Frances using two types of air-deployed neutrally buoyant and profiling underwater floats. Two "Lagrangian floats" measured O 2 and total gas tension (GT) in pre-storm and post-storm profiles and in the actively turbulent mixed layer during the storm. A single "EM-APEX float" profiled continuously from 30 to 200 m before, during and after the storm. All floats measured temperature and salinity. N 2 concentrations were computed from GT and O 2 after correcting for instrumental effects. Gas fluxes were computed by three methods. First, a one-dimensional mixed layer budget diagnosed the changes in mixed layer concentrations given the pre-storm profile and a time varying mixed layer depth. This model was calibrated using temperature and salinity data. The difference between the predicted mixed layer concentrations of O 2 and N 2 and those measured was attributed to air-sea gas fluxes FBO and FBN. Second, the covariance flux FCO( z) = < wO 2'>( z) was computed, where w is the vertical motion of the water-following Lagrangian floats, O 2' is a high-pass filtered O 2 concentration and <>( z) is an average over covariance pairs as a function of depth. The profile FCO( z) was extrapolated to the surface to yield the surface O 2 flux FCO(0). Third, a deficit of O 2 was found in the upper few meters of the ocean at the height of the storm. A flux FSO, moving O 2 out of the ocean, was calculated by dividing this deficit by the residence time of the water in this layer, inferred from the Lagrangian floats. The three methods gave generally consistent results. At the highest winds, gas transfer is dominated by bubbles created by surface wave breaking, injected into the ocean by large-scale turbulent eddies and dissolving near 10-m depth. This conclusion is supported by observations of fluxes into the ocean despite its supersaturation; by the molar flux ratio FBO/ FBN, which is

  14. Air sea gas exchange at extreme wind speeds measured by autonomous oceanographic floats

    NASA Astrophysics Data System (ADS)

    D'Asaro, Eric; McNeil, Craig

    2008-11-01

    Measurements of the air-sea fluxes of N 2 and O 2 were made in winds of 15-57 m s - 1 beneath Hurricane Frances using two types of air-deployed neutrally buoyant and profiling underwater floats. Two "Lagrangian floats" measured O 2 and total gas tension (GT) in pre-storm and post-storm profiles and in the actively turbulent mixed layer during the storm. A single "EM-APEX float" profiled continuously from 30 to 200 m before, during and after the storm. All floats measured temperature and salinity. N 2 concentrations were computed from GT and O 2 after correcting for instrumental effects. Gas fluxes were computed by three methods. First, a one-dimensional mixed layer budget diagnosed the changes in mixed layer concentrations given the pre-storm profile and a time varying mixed layer depth. This model was calibrated using temperature and salinity data. The difference between the predicted mixed layer concentrations of O 2 and N 2 and those measured was attributed to air-sea gas fluxes FBO and FBN. Second, the covariance flux FCO( z) = < wO 2'>( z) was computed, where w is the vertical motion of the water-following Lagrangian floats, O 2' is a high-pass filtered O 2 concentration and <>( z) is an average over covariance pairs as a function of depth. The profile FCO( z) was extrapolated to the surface to yield the surface O 2 flux FCO(0). Third, a deficit of O 2 was found in the upper few meters of the ocean at the height of the storm. A flux FSO, moving O 2 out of the ocean, was calculated by dividing this deficit by the residence time of the water in this layer, inferred from the Lagrangian floats. The three methods gave generally consistent results. At the highest winds, gas transfer is dominated by bubbles created by surface wave breaking, injected into the ocean by large-scale turbulent eddies and dissolving near 10-m depth. This conclusion is supported by observations of fluxes into the ocean despite its supersaturation; by the molar flux ratio FBO/ FBN, which is

  15. CO2 permeability of fractured cap rocks - experiments and numerical simulations (CO2Seals)

    NASA Astrophysics Data System (ADS)

    (Draeger), Ines Rick; Clauser, Christoph

    2010-05-01

    In CO2 sequestration and underground gas storage the sealing capacity of a cap rock is of paramount importance. The main question is therefore how the leakage of CO2 through fissures and faults within the cap rock may affect the CO2 sealing efficiency of low-permeable seal lithotypes. In many cases, these structures provide the main pathways for leakage of CO2. Here, we provide an overview of one part of the joint research project CO2Seals, which deals with the effect of structural features - such as tectonic faults and fissures in the overburden - on the migration of CO2 in addition to mineralogical, petrophysical, and geochemical properties of different lithotypes. The primary contribution of the entire project consists of an improvement of the present quantitative understanding of CO2 transport and retention processes and associated interactions in cap rocks between rock and CO2 or brine. To this end, we are adapting different numerical tools for simulating the relevant petrophysical and geochemical processes of CO2 in cap rocks, in close operation with: (1) large-scale CO2-percolation experiments on fractured cap rock samples; (2) permeability, gas breakthrough, and diffusion experiments; (3) measurements of the mechanical stability of cap rocks and the geochemical alterations of fault zone rock. The observed resulting changes in petrophysical properties, such as porosity, relative rock permeability (CO2 and brine), and fault permeability provide basics for the following numerical simulations. For example, first permeability tests of a marl and clay cap rock out of Cretaceous and Jurassic formations revealed gas permeability of 10-18 m2 down to 10-22 m2. In addition, first percolation experiments indicated that the influence of fault zones on the measured CO2 permeability of clays is very low. Furthermore, numerical bench-scale models are performed to provide confidence for the subsequent transfer to reservoir systems. Large-scale numerical models were created

  16. Air-sea heat exchange, an element of the water cycle

    NASA Technical Reports Server (NTRS)

    Chahine, M. T.

    1984-01-01

    The distribution and variation of water vapor, clouds and precipitation are examined. Principal driving forces for these distributions are energy exchange and evaporation at the air-sea interface, which are also important elements of air-sea interaction studies. The overall aim of air-sea interaction studies is to quantitatively determine mass, momentum and energy fluxes, with the goal of understanding the mechanisms controlling them. The results of general circulation simulations indicate that the atmosphere in mid-latitudes responds to changes in the oceanic surface conditions in the tropics. This correlation reflects the strong interaction between tropical and mid-latitude conditions caused by the transport of heat and momentum from the tropics. Studies of air-sea exchanges involve a large number of physica, chemical and dynamical processes including heat flux, radiation, sea-surface temperature, precipitation, winds and ocean currents. The fluxes of latent heat are studied and the potential use of satellite data in determining them evaluated. Alternative ways of inferring heat fluxes will be considered.

  17. Air-Sea Fluxes in Hurricanes From GPS Dropsondes and a Fully Coupled Model

    NASA Astrophysics Data System (ADS)

    Desflots, M.; Chen, S.; Zhao, W.; Bao, J.

    2006-12-01

    The importance of the surface fluxes for tropical cyclone (TC) intensity has long been recognized. However, accurate surface fluxes under extreme high-wind conditions are difficult to determine due to the lack of direct observations. The physical processes controlling the air-sea fluxes and the exchange coefficients for the enthalpy and momentum fluxes are not well understood. Furthermore, a large amount of sea spray produced by the breaking waves in high winds further complicates the processes at the air-sea interface. To understand the behaviour of the surface fluxes and the atmospheric and upper ocean boundary layers in a hurricane, we use a high-resolution (1-2 km grid spacing), fully coupled atmosphere-wave-ocean model. The components of the coupled model system are the 5th generation Pennsylvania State University/ National Center for Atmospheric Research non-hydrostatic Mesoscale Model (MM5), WAVEWATCH III (WW3), and the Woods Hole Oceanographic Institution three-dimensional upper ocean model (WHOI 3DPWP). The coupled model used in this study includes the CBLAST wind-wave coupling parameterization and a sea spray parameterization that include the effects of the surface waves. The sea spray parameterization was initially developed by Fairall et al. (1994) and modified by Bao et al. (2000). The model simulated air-sea fluxes and atmospheric profiles from several numerical experiments of a 5-day simulation of Hurricane Frances (2004) are compared with the Global Positioning System (GPS) dropsonde data. The coupled model simulations of Frances reproduce the observed storm track and intensity quite well. The observed cold wake at the ocean surface and the asymmetry in the air-sea fluxes are also evident in the model simulations. More detailed analysis is currently underway to better understand the physical processes affecting air-sea fluxes in hurricanes as well as their contribution to the storm structure and intensity.

  18. Air-Sea Interaction Measurements from the Controlled Towed Vehicle

    NASA Astrophysics Data System (ADS)

    Khelif, D.; Bluth, R. T.; Jonsson, H.; Barge, J.

    2014-12-01

    The Controlled Towed Vehicle (CTV) uses improved towed drone technology to actively maintain via a radar altimeter and controllable wing a user-set height that can be as low as the canonical reference height of 10 m above the sea surface. After take-off, the drone is released from the tow aircraft on a ~700-m stainless steel cable. We have instrumented the 0.23 m diameter and 2.13 m long drone with high fidelity instruments to measure the means and turbulent fluctuations of 3-D wind vector, temperature, humidity, pressure, CO2 and IR sea surface temperature. Data are recorded internally at 40 Hz and simultaneously transmitted to the tow aircraft via dedicated wireless Ethernet link. The CTV accommodates 40 kg of instrument payload and provides it with 250 W of continuous power through a ram air propeller-driven generator. Therefore its endurance is only limited by that of the tow aircraft.We will discuss the CTV development, the engineering challenges and solutions that have been successfully implemented to overcome them. We present results from recent flights as low as 9 m over the coastal ocean and comparisons of profiles and turbulent fluxes from the CTV and the tow aircraft. Manned aircraft operation at low-level boundary-layer flights is very limited. Dropsondes and UAS (Unmanned Aerial Systems) and UAS are alternates for measurements near the ocean surface. However, dropsondes have limited sensor capability and do not measure fluxes, and most present UAS vehicles do not have the payload and power capacity nor the low-flying ability in high winds over the oceans. The CTV therefore, fills a needed gap between the dropsondes, in situ aircraft, and UAS. The payload, capacity and power of the CTV makes it suitable for a variety of atmospheric research measurements. Other sensors to measure aerosol, chemistry, radiation, etc., could be readily accommodated in the CTV.

  19. Electron distribution in the nonclassical bis(dithiolene) electron transfer series [M(CO)2(S2C2Me2)2]0/1-/2- (M = Mo, W): assessment by structural, spectroscopic, and density functional theory results.

    PubMed

    Fomitchev, D V; Lim, B S; Holm, R H

    2001-02-12

    The electron-transfer series [M(CO)2(S2C2Me2)2]0/1-/2- (series 2) have been established, and the previously reported series [M(S2C2Me2)3]0/1-/2- (series 3) confirmed, by voltammetry (M = Mo, W). Redox reactions are reversible with EMo > EW, and all members of each series have been isolated. Members of a given series have very similar distorted trigonal prismatic structures; isoelectronic complexes are isostructural. The existence of these series with structurally characterized members facilitates examination of geometric and electronic properties over three consecutive oxidation states. Upon traversing the series in the reducing direction, M-S, S-C, and C-O bond distances increase, and M-C, chelate ring C-C, and vCO values decrease. Density functional calculations identify the electroactive orbital, which is well separated in energy from other orbitals. Trends in bond lengths and vibrational frequencies in a given series are fully accountable in terms of increasing population of this orbital, whose composition is roughly constant across the series and is dominantly ligand (ca. 80%) in character. Consequently, redox reactions in the two series are essentially ligand-based. The noninnocent nature of dithiolene ligands in oxidized complexes has been long recognized. The results of DFT calculations provide a contemporary description of the delocalized ground states in the two series. The trends in parameters involving the carbonyl groups provide a particularly clear indication of the classical behavior of a pi-acceptor ligand in isostructural molecules subject to consecutive reductions over three oxidation states.

  20. Co2 On Titan's Surface

    NASA Astrophysics Data System (ADS)

    McCord, Thomas B.; Combe, J.; Hayne, P.; Hansen, G. B.

    2007-10-01

    Evidence is reported for the presence of CO2 on the surface of Titan from the Cassini VIMS (an imaging visual and IR spectrometer) data (McCord et al., 2006, 2007). CO2 can be expected on Titan from basic planetary evolution models. It was also suggested as a plausible spectral component for bright material near the Huygens landing site (Rodriguez et al., 2006), based on structure in the 1.59-µm region. Hartung et al. (2006) searched for CO2 in one hemisphere, but they were able only to set an upper limit on the possible spatial coverage by pure CO2. Barnes et al., (2006) suggested CO2 as a possible candidate material for a 5-µm-bright region, named Tsegihi, based on the high 5-µm reflectance. However, these results are not inconsistent with our report. The evidence we report is three-fold: 1) A weak absorption near 4.9 µm in the 5-µm methane window for the Tui Regio region; 2) The spectral contrast between the 2.7- and 2.8-µm methane subwindows for the regions exhibiting the 4.9-µm absorption, with stronger absorption correlating with stronger contrast; and 3) the overall shape of the CO2 spectrum (for several grain-sizes) is consistent with the spectrum of one of the fundamental surface spectral components, as deduced by spectral mixture analysis modeling. The Tui Regio feature exhibits the strongest evidence in all three categories. Studies of this feature's morphology and albedo markings have suggested to some that it may be an active cryovolcanic feature (Barnes et al., 2006). If so, CO2 could be erupting and depositing as a frost. This likely happened elsewhere and at other times. Thus, CO2 could be a major constituent of the surface, but over time it may be mixed with other constituents, such as spectrally neutral organics raining from the atmosphere, thereby reducing the strength of its spectral signature.

  1. CO2 emissions from German drinking water reservoirs.

    PubMed

    Saidi, Helmi; Koschorreck, Matthias

    2017-03-01

    Globally, reservoirs are a significant source of atmospheric CO2. However, precise quantification of greenhouse gas emissions from drinking water reservoirs on the regional or national scale is still challenging. We calculated CO2 fluxes for 39 German drinking water reservoirs during a period of 22years (1991-2013) using routine monitoring data in order to quantify total emission of CO2 from drinking water reservoirs in Germany and to identify major drivers. All reservoirs were a net CO2 source with a median flux of 167gCm(-2)y(-1), which makes gaseous emissions a relevant process for the carbon budget of each reservoir. Fluxes varied seasonally with median fluxes of 13, 48, and 201gCm(-2)y(-1) in spring, summer, and autumn respectively. Differences between reservoirs appeared to be primarily caused by the concentration of CO2 in the surface water rather than by the physical gas transfer coefficient. Consideration of short term fluctuations of the gas transfer coefficient due to varying wind speed had only a minor effect on the annual budgets. High CO2 emissions only occurred in reservoirs with pH<7 and total alkalinity <0.2mEql(-1). Annual CO2 emissions correlated exponentially with pH but not with dissolved organic carbon (DOC). There was significant correlation between land use in the catchment and CO2 emissions. In total, German drinking water reservoirs emit 44000t of CO2 annually, which makes them a negligible CO2 source (<0.005% of national CO2 emissions) in Germany.

  2. Element budgets in an Arctic mesocosm CO2 perturbation study

    NASA Astrophysics Data System (ADS)

    Czerny, J.; Schulz, K. G.; Boxhammer, T.; Bellerby, R. G. J.; Büdenbender, J.; Engel, A.; Krug, S. A.; Ludwig, A.; Nachtigall, K.; Nondal, G.; Niehoff, B.; Siljakova, A.; Riebesell, U.

    2012-08-01

    Recent studies on the impacts of ocean acidification on pelagic communities have identified changes in carbon to nutrient dynamics with related shifts in elemental stoichiometry. In principle, mesocosm experiments provide the opportunity of determining the temporal dynamics of all relevant carbon and nutrient pools and, thus, calculating elemental budgets. In practice, attempts to budget mesocosm enclosures are often hampered by uncertainties in some of the measured pools and fluxes, in particular due to uncertainties in constraining air/sea gas exchange, particle sinking, and wall growth. In an Arctic mesocosm study on ocean acidification using KOSMOS (Kiel Off-Shore Mesocosms for future Ocean Simulation) all relevant element pools and fluxes of carbon, nitrogen and phosphorus were measured, using an improved experimental design intended to narrow down some of the mentioned uncertainties. Water column concentrations of particulate and dissolved organic and inorganic constituents were determined daily. New approaches for quantitative estimates of material sinking to the bottom of the mesocosms and gas exchange in 48 h temporal resolution, as well as estimates of wall growth were developed to close the gaps in element budgets. Future elevated pCO2 was found to enhance net autotrophic community carbon uptake in 2 of the 3 experimental phases but did not significantly affect particle elemental composition. Enhanced carbon consumption appears to result in accumulation of dissolved organic compounds under nutrient recycling summer conditions. This carbon over-consumption effect becomes evident from budget calculations, but was too small to be resolved by direct measurements of dissolved organics. The out-competing of large diatoms by comparatively small algae in nutrient uptake caused reduced production rates under future ocean CO2 conditions in the end of the experiment. This CO2 induced shift away from diatoms towards smaller phytoplankton and enhanced cycling of

  3. Large CO2 effluxes at night and during synoptic weather events significantly contribute to CO2 emissions from a reservoir

    NASA Astrophysics Data System (ADS)

    Liu, Heping; Zhang, Qianyu; Katul, Gabriel G.; Cole, Jonathan J.; Chapin, F. Stuart, III; MacIntyre, Sally

    2016-06-01

    CO2 emissions from inland waters are commonly determined by indirect methods that are based on the product of a gas transfer coefficient and the concentration gradient at the air water interface (e.g., wind-based gas transfer models). The measurements of concentration gradient are typically collected during the day in fair weather throughout the course of a year. Direct measurements of eddy covariance CO2 fluxes from a large inland water body (Ross Barnett reservoir, Mississippi, USA) show that CO2 effluxes at night are approximately 70% greater than those during the day. At longer time scales, frequent synoptic weather events associated with extratropical cyclones induce CO2 flux pulses, resulting in further increase in annual CO2 effluxes by 16%. Therefore, CO2 emission rates from this reservoir, if these diel and synoptic processes are under-sampled, are likely to be underestimated by approximately 40%. Our results also indicate that the CO2 emission rates from global inland waters reported in the literature, when based on indirect methods, are likely underestimated. Field samplings and indirect modeling frameworks that estimate CO2 emissions should account for both daytime-nighttime efflux difference and enhanced emissions during synoptic weather events. The analysis here can guide carbon emission sampling to improve regional carbon estimates.

  4. Large CO2 effluxes at night and during synoptic weather events significantly contribute to CO2 emissions from a reservoir

    DOE PAGES

    Liu, Heping; Zhang, Qianyu; Katul, Gabriel G.; ...

    2016-05-24

    CO2 emissions from inland waters are commonly determined by indirect methods that are based on the product of a gas transfer coefficient and the concentration gradient at the air water interface (e.g., wind-based gas transfer models). The measurements of concentration gradient are typically collected during the day in fair weather throughout the course of a year. Direct measurements of eddy covariance CO2 fluxes from a large inland water body (Ross Barnett reservoir, Mississippi, USA) show that CO2 effluxes at night are approximately 70% greater than those during the day. At longer time scales, frequent synoptic weather events associated with extratropicalmore » cyclones induce CO2 flux pulses, resulting in further increase in annual CO2 effluxes by 16%. Therefore, CO2 emission rates from this reservoir, if these diel and synoptic processes are under-sampled, are likely to be underestimated by approximately 40%. Our results also indicate that the CO2 emission rates from global inland waters reported in the literature, when based on indirect methods, are likely underestimated. Field samplings and indirect modeling frameworks that estimate CO2 emissions should account for both daytime-nighttime efflux difference and enhanced emissions during synoptic weather events. Furthermore, the analysis here can guide carbon emission sampling to improve regional carbon estimates.« less

  5. ACCURACY OF CO2 SENSORS

    SciTech Connect

    Fisk, William J.; Faulkner, David; Sullivan, Douglas P.

    2008-10-01

    Are the carbon dioxide (CO2) sensors in your demand controlled ventilation systems sufficiently accurate? The data from these sensors are used to automatically modulate minimum rates of outdoor air ventilation. The goal is to keep ventilation rates at or above design requirements while adjusting the ventilation rate with changes in occupancy in order to save energy. Studies of energy savings from demand controlled ventilation and of the relationship of indoor CO2 concentrations with health and work performance provide a strong rationale for use of indoor CO2 data to control minimum ventilation rates1-7. However, this strategy will only be effective if, in practice, the CO2 sensors have a reasonable accuracy. The objective of this study was; therefore, to determine if CO2 sensor performance, in practice, is generally acceptable or problematic. This article provides a summary of study methods and findings ? additional details are available in a paper in the proceedings of the ASHRAE IAQ?2007 Conference8.

  6. Efficiency of CO2 fixation by microalgae in a closed raceway pond.

    PubMed

    Li, Shuwen; Luo, Shengjun; Guo, Rongbo

    2013-05-01

    Microalgae contain about 50% of carbon, which means that a total of 1.83 ton of CO2 is needed to produce 1 ton of microalgae. The cost of CO2 supply for microalgal large scale cultivation should be considered and the low CO2 fixation efficiency by microalgae will lead to much more expenditure of CO2. In this study, a closed raceway pond was constructed by covering a normal open raceway pond with a specially designed transparent cover, which directly touched the surface of microalgal culture media. This cover prevented supplied CO2 escaping into atmosphere and thus increased the retention time of CO2. The CO2 gas-liquid mass transfer and CO2 fixation efficiency by microalgae in the closed raceway pond were investigated, and the model of CO2 fixation by microalgae was developed. Through the model, the CO2 fixation efficiency increased to 95% under intermittent gas sparging.

  7. The impact on atmospheric CO2 of iron fertilization induced changes in the ocean's biological pump

    NASA Astrophysics Data System (ADS)

    Jin, X.; Gruber, N.; Frenzel, H.; Doney, S. C.; McWilliams, J. C.

    2008-03-01

    Using numerical simulations, we quantify the impact of changes in the ocean's biological pump on the air-sea balance of CO2 by fertilizing a small surface patch in the high-nutrient, low-chlorophyll region of the eastern tropical Pacific with iron. Decade-long fertilization experiments are conducted in a basin-scale, eddy-permitting coupled physical/biogeochemical/ecological model. In contrast to previous studies, we find that most of the dissolved inorganic carbon (DIC) removed from the euphotic zone by the enhanced biological export is replaced by uptake of CO2 from the atmosphere. Atmospheric uptake efficiencies, the ratio of the perturbation in air-sea CO2 flux to the perturbation in export flux across 100 m, integrated over 10 years, are 0.75 to 0.93 in our patch size-scale experiments. The atmospheric uptake efficiency is insensitive to the duration of the experiment. The primary factor controlling the atmospheric uptake efficiency is the vertical distribution of the enhanced biological production and export. Iron fertilization at the surface tends to induce production anomalies primarily near the surface, leading to high efficiencies. In contrast, mechanisms that induce deep production anomalies (e.g. altered light availability) tend to have a low uptake efficiency, since most of the removed DIC is replaced by lateral and vertical transport and mixing. Despite high atmospheric uptake efficiencies, patch-scale iron fertilization of the ocean's biological pump tends to remove little CO2 from the atmosphere over the decadal timescale considered here.

  8. Update on CO2 emissions

    SciTech Connect

    Friedingstein, P.; Houghton, R.A.; Marland, Gregg; Hackler, J.; Boden, Thomas A; Conway, T.J.; Canadell, J.G.; Raupach, Mike; Ciais, Philippe; Le Quere, Corrine

    2010-12-01

    Emissions of CO2 are the main contributor to anthropogenic climate change. Here we present updated information on their present and near-future estimates. We calculate that global CO2 emissions from fossil fuel burning decreased by 1.3% in 2009 owing to the global financial and economic crisis that started in 2008; this is half the decrease anticipated a year ago1. If economic growth proceeds as expected2, emissions are projected to increase by more than 3% in 2010, approaching the high emissions growth rates that were observed from 2000 to 20081, 3, 4. We estimate that recent CO2 emissions from deforestation and other land-use changes (LUCs) have declined compared with the 1990s, primarily because of reduced rates of deforestation in the tropics5 and a smaller contribution owing to forest regrowth elsewhere.

  9. Towards Overhauser DNP in supercritical CO2

    NASA Astrophysics Data System (ADS)

    van Meerten, S. G. J.; Tayler, M. C. D.; Kentgens, A. P. M.; van Bentum, P. J. M.

    2016-06-01

    Overhauser Dynamic Nuclear Polarization (ODNP) is a well known technique to improve NMR sensitivity in the liquid state, where the large polarization of an electron spin is transferred to a nucleus of interest by cross-relaxation. The efficiency of the Overhauser mechanism for dipolar interactions depends critically on fast local translational dynamics at the timescale of the inverse electron Larmor frequency. The maximum polarization enhancement that can be achieved for 1H at high magnetic fields benefits from a low viscosity solvent. In this paper we investigate the option to use supercritical CO2 as a solvent for Overhauser DNP. We have investigated the diffusion constants and longitudinal nuclear relaxation rates of toluene in high pressure CO2. The change in 1H T1 by addition of TEMPO radical was analyzed to determine the Overhauser cross-relaxation in such a mixture, and is compared with calculations based on the Force Free Hard Sphere (FFHS) model. By analyzing the relaxation data within this model we find translational correlation times in the range of 2-4 ps, depending on temperature, pressure and toluene concentration. Such short correlation times may be instrumental for future Overhauser DNP applications at high magnetic fields, as are commonly used in NMR. Preliminary DNP experiments have been performed at 3.4 T on high pressure superheated water and model systems such as toluene in high pressure CO2.

  10. Towards Overhauser DNP in supercritical CO2.

    PubMed

    van Meerten, S G J; Tayler, M C D; Kentgens, A P M; van Bentum, P J M

    2016-06-01

    Overhauser Dynamic Nuclear Polarization (ODNP) is a well known technique to improve NMR sensitivity in the liquid state, where the large polarization of an electron spin is transferred to a nucleus of interest by cross-relaxation. The efficiency of the Overhauser mechanism for dipolar interactions depends critically on fast local translational dynamics at the timescale of the inverse electron Larmor frequency. The maximum polarization enhancement that can be achieved for (1)H at high magnetic fields benefits from a low viscosity solvent. In this paper we investigate the option to use supercritical CO2 as a solvent for Overhauser DNP. We have investigated the diffusion constants and longitudinal nuclear relaxation rates of toluene in high pressure CO2. The change in (1)H T1 by addition of TEMPO radical was analyzed to determine the Overhauser cross-relaxation in such a mixture, and is compared with calculations based on the Force Free Hard Sphere (FFHS) model. By analyzing the relaxation data within this model we find translational correlation times in the range of 2-4ps, depending on temperature, pressure and toluene concentration. Such short correlation times may be instrumental for future Overhauser DNP applications at high magnetic fields, as are commonly used in NMR. Preliminary DNP experiments have been performed at 3.4T on high pressure superheated water and model systems such as toluene in high pressure CO2.

  11. Variation of pCO2 in ocean surface water in response to the passage of a hurricane

    NASA Astrophysics Data System (ADS)

    Huang, Peisheng; Imberger, JöRg

    2010-10-01

    The temporal and spatial variations of pCO2 in the ocean surface layer in response to the passage of Hurricane Frances (2004) were investigated with a coupled three-dimensional hydrodynamic and carbon model. The results showed that the sea surface temperature cooling was the dominant cause of the decrease of surface pCO2, while the entrainment of water with higher CO2 levels partially offset the cooling-induced decrease. The surface distribution of pCO2 was thus found to mimic the physical deepening processes, with a "right bias" to the hurricane track. The impact of the hurricane on the local air-sea CO2 exchange extended to about 100 km on both sides of the hurricane track. The whole passage of Hurricane Frances was estimated to have caused a CO2 efflux of about 3.504-10.363 Tg (1 Tg = 1012 g) C from ocean to the atmosphere. Globally, hurricanes in 2004 were estimated to have released a CO2 efflux of 0.047-0.141 Pg (1 Pg = 1015 g) C in total when extrapolating from Hurricane Frances. Under our assumptions, the CO2 efflux caused by the passages of global hurricanes should have increased by about 71.2%-75.0% in past decades.

  12. The CO2nnect activities

    NASA Astrophysics Data System (ADS)

    Eugenia, Marcu

    2014-05-01

    Climate change is one of the biggest challenges we face today. A first step is the understanding the problem, more exactly what is the challenge and the differences people can make. Pupils need a wide competencies to meet the challenges of sustainable development - including climate change. The CO2nnect activities are designed to support learning which can provide pupils the abilities, skills, attitudes and awareness as well as knowledge and understanding of the issues. The project "Together for a clean and healthy world" is part of "The Global Educational Campaign CO2nnect- CO2 on the way to school" and it was held in our school in the period between February and October 2009. It contained a variety of curricular and extra-curricular activities, adapted to students aged from 11 to 15. These activities aimed to develop in students the necessary skills to understanding man's active role in improving the quality of the environment, putting an end to its degrading process and to reducing the effects of climate changes caused by the human intervention in nature, including transport- a source of CO2 pollution. The activity which I propose can be easily adapted to a wide range of age groups and linked to the curricula of many subjects: - Investigate CO2 emissions from travel to school -Share the findings using an international database -Compare and discuss CO2 emissions -Submit questions to a climate- and transport expert -Partner with other schools -Meet with people in your community to discuss emissions from transport Intended learning outcomes for pupils who participate in the CO2nnect campaign are: Understanding of the interconnected mobility- and climate change issue climate change, its causes and consequences greenhouse-gas emissions from transport and mobility the interlinking of social, environmental, cultural and economic aspects of the local transport system how individual choices and participation can contribute to creating a more sustainable development

  13. The impact of Southern Ocean residual upwelling on atmospheric CO2 on centennial and millennial timescales

    NASA Astrophysics Data System (ADS)

    Lauderdale, Jonathan M.; Williams, Richard G.; Munday, David R.; Marshall, David P.

    2017-03-01

    The Southern Ocean plays a pivotal role in climate change by exchanging heat and carbon, and provides the primary window for the global deep ocean to communicate with the atmosphere. There has been a widespread focus on explaining atmospheric CO2 changes in terms of changes in wind forcing in the Southern Ocean. Here, we develop a dynamically-motivated metric, the residual upwelling, that measures the primary effect of Southern Ocean dynamics on atmospheric CO2 on centennial to millennial timescales by determining the communication with the deep ocean. The metric encapsulates the combined, net effect of winds and air-sea buoyancy forcing on both the upper and lower overturning cells, which have been invoked as explaining atmospheric CO2 changes for the present day and glacial-interglacial changes. The skill of the metric is assessed by employing suites of idealized ocean model experiments, including parameterized and explicitly simulated eddies, with online biogeochemistry and integrated for 10,000 years to equilibrium. Increased residual upwelling drives elevated atmospheric CO2 at a rate of typically 1-1.5 parts per million/106 m3 s-1 by enhancing the communication between the atmosphere and deep ocean. This metric can be used to interpret the long-term effect of Southern Ocean dynamics on the natural carbon cycle and atmospheric CO2, alongside other metrics, such as involving the proportion of preformed nutrients and the extent of sea ice cover.

  14. Mueller matrix imaging of targets under an air-sea interface.

    PubMed

    Zhai, Peng-Wang; Kattawar, George W; Yang, Ping

    2009-01-10

    The Mueller matrix imaging method is a powerful tool for target detection. In this study, the effect of the air-sea interface on the detection of underwater objects is studied. A backward Monte Carlo code has been developed to study this effect. The main result is that the reflection of the diffuse sky light by the interface reduces the Mueller image contrast. If the air-sea interface is ruffled by wind, the distinction between different regions of the underwater target is smoothed out. The effect of the finite size of an active light source is also studied. The image contrast is found to be relatively insensitive to the size of the light source. The volume scattering function plays an important role on the underwater object detection. Generally, a smaller asymmetry parameter decreases the contrast of the polarimetry images.

  15. Biopolymers form a gelatinous microlayer at the air-sea interface when Arctic sea ice melts.

    PubMed

    Galgani, Luisa; Piontek, Judith; Engel, Anja

    2016-07-20

    The interface layer between ocean and atmosphere is only a couple of micrometers thick but plays a critical role in climate relevant processes, including the air-sea exchange of gas and heat and the emission of primary organic aerosols (POA). Recent findings suggest that low-level cloud formation above the Arctic Ocean may be linked to organic polymers produced by marine microorganisms. Sea ice harbors high amounts of polymeric substances that are produced by cells growing within the sea-ice brine. Here, we report from a research cruise to the central Arctic Ocean in 2012. Our study shows that microbial polymers accumulate at the air-sea interface when the sea ice melts. Proteinaceous compounds represented the major fraction of polymers supporting the formation of a gelatinous interface microlayer and providing a hitherto unrecognized potential source of marine POA. Our study indicates a novel link between sea ice-ocean and atmosphere that may be sensitive to climate change.

  16. Biopolymers form a gelatinous microlayer at the air-sea interface when Arctic sea ice melts

    NASA Astrophysics Data System (ADS)

    Galgani, Luisa; Piontek, Judith; Engel, Anja

    2016-07-01

    The interface layer between ocean and atmosphere is only a couple of micrometers thick but plays a critical role in climate relevant processes, including the air-sea exchange of gas and heat and the emission of primary organic aerosols (POA). Recent findings suggest that low-level cloud formation above the Arctic Ocean may be linked to organic polymers produced by marine microorganisms. Sea ice harbors high amounts of polymeric substances that are produced by cells growing within the sea-ice brine. Here, we report from a research cruise to the central Arctic Ocean in 2012. Our study shows that microbial polymers accumulate at the air-sea interface when the sea ice melts. Proteinaceous compounds represented the major fraction of polymers supporting the formation of a gelatinous interface microlayer and providing a hitherto unrecognized potential source of marine POA. Our study indicates a novel link between sea ice-ocean and atmosphere that may be sensitive to climate change.

  17. Disentangling the air-sea interaction in the South Atlantic Convergence Zone

    NASA Astrophysics Data System (ADS)

    tirabassi, giulio; masoller, cristina; barreiro, marcelo

    2014-05-01

    Air-sea interaction in the region of the South Atlantic Convergence Zone (SACZ) is disentangled using Granger causality as a measure of directional coupling. Calculation of the area weighted connectivity indicates that the SACZ region is the one with largest mutual air-sea connectivity in the south Atlantic basin during summertime. Focusing on the leading mode of daily coupled variability, Granger causality allows distinguishing four regimes characterized by different coupling: there are years in which the forcing is mainly directed from the atmosphere to the ocean, years in which the ocean forces the atmosphere, years in which the influence is mutual, and years in which the coupling is not significant. A composite analysis shows that ocean-driven events have atmospheric anomalies that develop first and are strongest over the ocean, while in events without coupling anomalies develop from the continent where they are strongest and have weaker oceanic extension.

  18. Sea surface temperature anomalies, planetary waves, and air-sea feedback in the middle latitudes

    NASA Technical Reports Server (NTRS)

    Frankignoul, C.

    1985-01-01

    Current analytical models for large-scale air-sea interactions in the middle latitudes are reviewed in terms of known sea-surface temperature (SST) anomalies. The scales and strength of different atmospheric forcing mechanisms are discussed, along with the damping and feedback processes controlling the evolution of the SST. Difficulties with effective SST modeling are described in terms of the techniques and results of case studies, numerical simulations of mixed-layer variability and statistical modeling. The relationship between SST and diabatic heating anomalies is considered and a linear model is developed for the response of the stationary atmosphere to the air-sea feedback. The results obtained with linear wave models are compared with the linear model results. Finally, sample data are presented from experiments with general circulation models into which specific SST anomaly data for the middle latitudes were introduced.

  19. A Numerical Study of the Role of Air-Sea Fluxes in Extratropical Cyclogenesis.

    DTIC Science & Technology

    1981-09-01

    Extratropical Cyclogenesis; Air-sea Fluxes; Surface Fluxes; Ocean Cyclogenesis; Polar Low;KDiabatic Processes 20. \\#@SYrNACY (Coie. on Po~wes li It nRaea@inF...parameterization scheme and the Randall version of the Deardorff planetary boundary layer parameterization. Idealized initial conditions are speci- fied ...hydo- static equation. The reference geopotential profile is speci- fied at 300S (spring regime) in the balance routine to match the temperature field

  20. Air-Sea and Lateral Exchange Processes in East Indian Coastal Current off Sri Lanka

    DTIC Science & Technology

    2015-09-30

    of which have a bearing on local air-sea fluxes. The project seeks to collect hydrographic data sets in the international waters (R/V Roger Revelle...and in Sri Lankan coastal waters (R/V Samuddrika). The measurements include thermohaline stratification, currents and the kinetic energy...conducted CTD and ADCP measurements in the southern BoB onboard R/V Roger Revelle and in Sri Lanka coastal waters using R/V Samuddrika. The data analysis

  1. Small Autonomous Air/Sea System Concepts for Coast Guard Missions

    NASA Technical Reports Server (NTRS)

    Young, Larry A.

    2005-01-01

    A number of small autonomous air/sea system concepts are outlined in this paper that support and enhance U.S. Coast Guard missions. These concepts draw significantly upon technology investments made by NASA in the area of uninhabited aerial vehicles and robotic/intelligent systems. Such concepts should be considered notional elements of a greater as-yet-not-defined robotic system-of-systems designed to enable unparalleled maritime safety and security.

  2. Global and regional drivers of nutrient supply, primary production and CO2 drawdown in the changing Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Tremblay, Jean-Éric; Anderson, Leif G.; Matrai, Patricia; Coupel, Pierre; Bélanger, Simon; Michel, Christine; Reigstad, Marit

    2015-12-01

    -Arctic scale. While CO2 intake by the Arctic Ocean should respond positively to reduced sea-ice extent, which facilitates air-sea exchange, the negative influence of rising temperatures and runoff on CO2 solubility might counteract the positive effect of modest PP increases in seasonally open waters. Overall, this review shows that local changes in light availability resulting from reduced sea-ice is only one factor in the intricate web of local and remote drivers of PP and CO2 drawdown in the Arctic Ocean. Understanding and predicting change requires an integrated biogeochemical approach that connects the small Arctic Ocean to adjacent ones and adequately resolves vertical nutrient supply processes at regional and local scales.

  3. A two-dimensional model with coupled dynamics, radiative transfer, and photochemistry. 2: Assessment of the response of stratospheric ozone to increased levels of CO2, N2O, CH4, and CFC

    NASA Technical Reports Server (NTRS)

    Schneider, Hans R.; Ko, Malcolm K. W.; Shia, Run-Lie; Sze, Nien-Dak

    1993-01-01

    The impact of increased levels of carbon dioxide (CO2), chlorofluorocarbons (CFCs), and other trace gases on stratospheric ozone is investigated with an interactive, two-dimensional model of gas phase chemistry, dynamics, and radiation. The scenarios considered are (1) a doubling of the CO2 concentration, (2) increases of CFCs, (3) CFC increases combined with increases of nitrous oxide (N2O) and methane CH4, and (4) the simultaneous increase of CO2, CFCs, N2O, and CH4. The radiative feedback and the effect of temperature and circulation changes are studied for each scenario. For the double CO2 calculations the tropospheric warming was specified. The CO2 doubling leads to a 3.1% increase in the global ozone content. Doubling of the CO2 concentrations would lead to a maximum cooling of about 12 C at 45 km if the ozone concentration were held fixed. The cooling of the stratosphere leads to an ozone increase with an associated increase in solar heating, reducing the maximum temperature drop by about 3 C. The CFC increase from continuous emissions at 1985 rate causes a 4.5% loss of ozone. For the combined perturbations a net loss of 1.3% is calculated. The structure of the perturbations shows a north-south asymmetry. Ozone losses (when expressed in terms of percent changes) are generally larger in the high latitudes of the southern hemisphere as a result of the eddy mixing being smaller than in the northern hemisphere. Increase of chlorine leads to ozone losses above 30 km altitude where the radiative feedback results in a cooler temperature and an ozone recovery of about one quarter of the losses predicted with a noninteractive model. In all the cases, changes in circulation are small. In the chlorine case, circulation changes reduce the calculated column depletion by about one tenth compared to offline calculations.

  4. Linking air-sea energy exchanges and European anchovy potential spawning ground

    NASA Astrophysics Data System (ADS)

    Grammauta, R.; Molteni, D.; Basilone, G.; Guisande, C.; Bonanno, A.; Aronica, S.; Giacalone, G.; Fontana, I.; Zora, M.; Patti, B.; Cuttitta, A.; Buscaino, G.; Sorgente, R.; Mazzola, S.

    2008-10-01

    The physical and chemical processes of the sea greatly affect the reproductive biology of fishes, mainly influencing both the numbers of spawned eggs and the survivorship of early stages up to the recruitment period. In the central Mediterranean, the European anchovy constitutes one of the most important fishery resource. Because of its short living nature and of its recruitment variability, associated to high environmental variability, this small pelagic species undergo high interannual fluctuation in the biomass levels. Despite several efforts were addressed to characterize fishes spawning habitat from the oceanographic point of view, very few studies analyze the air-sea exchanges effects. To characterize the spawning habitat of these resources a specific technique (quotient rule analysis) was applied on air-sea heat fluxes, wind stress, sea surface temperature and turbulence data, collected in three oceanographic surveys during the summer period of 2004, 2005 and 2006. The results showed the existence of preferred values in the examined physical variables, associated to anchovy spawning areas. Namely, for heat fluxes the values were around -40 W/m2, for wind stress 0.04-0.11 N/m2, for SST 23°C, and 300 - 500 m3s-3 for wind mixing. Despite the obtained results are preliminary, this is the first relevant analysis on the air-sea exchanges and their relationship with the fish biology of pelagic species.

  5. Reducing cement's CO2 footprint

    USGS Publications Warehouse

    van Oss, Hendrik G.

    2011-01-01

    The manufacturing process for Portland cement causes high levels of greenhouse gas emissions. However, environmental impacts can be reduced by using more energy-efficient kilns and replacing fossil energy with alternative fuels. Although carbon capture and new cements with less CO2 emission are still in the experimental phase, all these innovations can help develop a cleaner cement industry.

  6. Effect of air-sea coupling on the frequency distribution of intense tropical cyclones over the northwestern Pacific

    NASA Astrophysics Data System (ADS)

    Ogata, Tomomichi; Mizuta, Ryo; Adachi, Yukimasa; Murakami, Hiroyuki; Ose, Tomoaki

    2015-12-01

    Effect of air-sea coupling on the frequency distribution of intense tropical cyclones (TCs) over the northwestern Pacific (NWP) region is investigated using an atmosphere and ocean coupled general circulation model (AOGCM). Monthly varying flux adjustment enables AOGCM to simulate both subseasonal air-sea interaction and realistic seasonal to interannual sea surface temperature (SST) variability. The maximum of intense TC distribution around 20-30°N in the AGCM shifts equatorward in the AOGCM due to the air-sea coupling. Hence, AOGCM reduces northward intense TC distribution bias seen in AGCM. Over the NWP, AOGCM-simulated SST variability is large around 20-30°N where the warm mixed layer becomes shallower rapidly. Active entrainment from subsurface water over this region causes stronger SST cooling, and hence, TC intensity decreases. These results suggest that air-sea coupling characterized by subsurface oceanic condition causes more realistic distribution of intense TCs over the NWP.

  7. Efficient CO2 capture and photoreduction by amine-functionalized TiO2.

    PubMed

    Liao, Yusen; Cao, Shao-Wen; Yuan, Yupeng; Gu, Quan; Zhang, Zhenyi; Xue, Can

    2014-08-11

    Amine-functionalization of TiO2 nanoparticles, through a solvothermal approach, substantially increases the affinity of CO2 on TiO2 surfaces through chemisorption. This chemisorption allows for more effective activation of CO2 and charge transfer from excited TiO2 , and significantly enhances the photocatalytic rate of CO2 reduction into methane and CO.

  8. Measuring the Absorption Rate of CO2 in Nonaqueous CO2-Binding Organic Liquid Solvents with a Wetted-Wall Apparatus.

    PubMed

    Mathias, Paul M; Zheng, Feng; Heldebrant, David J; Zwoster, Andy; Whyatt, Greg; Freeman, Charles M; Bearden, Mark D; Koech, Phillip

    2015-11-01

    The kinetics of the absorption of CO2 into two nonaqueous CO2-binding organic liquid (CO2 BOL) solvents were measured at T=35, 45, and 55 °C with a wetted-wall column. Selected CO2 loadings were run with a so-called "first-generation" CO2 BOL, comprising an independent base and alcohol, and a "second-generation" CO2 BOL, in which the base and alcohol were conjoined. Liquid-film mass-transfer coefficient (k'g ) values for both solvents were measured to be comparable to values for monoethanolamine and piperazine aqueous solvents under a comparable driving force, in spite of far higher solution viscosities. An inverse temperature dependence of the k'g value was also observed, which suggests that the physical solubility of CO2 in organic liquids may be making CO2 mass transfer faster than expected. Aspen Plus software was used to model the kinetic data and compare the CO2 absorption behavior of nonaqueous solvents with that of aqueous solvent platforms. This work continues our development of the CO2 BOL solvents. Previous work established the thermodynamic properties related to CO2 capture. The present paper quantitatively studies the kinetics of CO2 capture and develops a rate-based model.

  9. CO2 exchange coefficients from remotely sensed wind speed measurements: SSM/I versus QuikSCAT in 2000

    NASA Astrophysics Data System (ADS)

    Carr, Mary-Elena; Tang, Wenqing; Liu, W. Timothy

    2002-08-01

    We compare here the air-sea exchange coefficient for CO2 estimated with monthly mean wind speed measured by the Special Sensing Microwave Imager (SSM/I), KS, and by the scatterometer QuikSCAT, KQ, for the year 2000. KS and KQ present the same patterns, although are larger than in ~65% of the world ocean. Zonal mean KS are consistently larger, except ~50°S and north of 10°S in the Indian Ocean. Global oceanic uptake, FQ, estimated using KQ and climatological ΔpCO2 ranges from 0.43 (July) to 2.6 Gt C y-1 (December). The global sink estimated from SSM/I is ~10% larger than FQ for most of the year. This comparison supports the use of SSM/I to quantify interannual variability of the global exchange coefficient of CO2.

  10. High resolution measurements of methane and carbon dioxide in surface waters over a natural seep reveal dynamics of dissolved phase air-sea flux.

    PubMed

    Du, Mengran; Yvon-Lewis, Shari; Garcia-Tigreros, Fenix; Valentine, David L; Mendes, Stephanie D; Kessler, John D

    2014-09-02

    Marine hydrocarbon seeps are sources of methane and carbon dioxide to the ocean, and potentially to the atmosphere, though the magnitude of the fluxes and dynamics of these systems are poorly defined. To better constrain these variables in natural environments, we conducted the first high-resolution measurements of sea surface methane and carbon dioxide concentrations in the massive natural seep field near Coal Oil Point (COP), California. The corresponding high resolution fluxes were calculated, and the total dissolved phase air-sea fluxes over the surveyed plume area (∼363 km(2)) were 6.66 × 10(4) to 6.71 × 10(4) mol day(-1) with respect to CH4 and -6.01 × 10(5) to -5.99 × 10(5) mol day(-1) with respect to CO2. The mean and standard deviation of the dissolved phase air-sea fluxes of methane and carbon dioxide from the contour gridding analysis were estimated to be 0.18 ± 0.19 and -1.65 ± 1.23 mmol m(-2) day(-1), respectively. This methane flux is consistent with previous, lower-resolution estimates and was used, in part, to conservatively estimate the total area of the dissolved methane plume at 8400 km(2). The influx of carbon dioxide to the surface water refutes the hypothesis that COP seep methane appreciably influences carbon dioxide dynamics. Seeing that the COP seep field is one of the biggest natural seeps, a logical conclusion could be drawn that microbial oxidation of methane from natural seeps is of insufficient magnitude to change the resulting plume area from a sink of atmospheric carbon dioxide to a source.

  11. Western Pacific Air-Sea Interaction Study (W-PASS), Introduction and Highlights (Invited)

    NASA Astrophysics Data System (ADS)

    Tsuda, A.

    2010-12-01

    Western Pacific Air-Sea Interaction Study (W-PASS), Introduction and Highlights Atsushi Tsuda Atmosphere and Ocean Research Institute, The University of Tokyo In the western Pacific (WESTPAC) region, dust originating from Asian and Australian arid regions to the North and South Pacific, biomass burning emissions from the Southeast Asia to sub-tropical Pacific, and other anthropogenic substances are transported regionally and globally to affect cloud and rainfall patterns, air quality, and radiative budgets downwind. Deposition of these compounds into the Asian marginal seas and onto the Pacific Ocean influence surface primary productivity and species composition. In the WESTPAC region, subarctic, subtropical oceans and marginal seas are located relatively narrow latitudinal range and these areas are influenced by the dust and anthropogenic inputs. Moreover, anthropogenic emission areas are located between the arid region and the oceans. The W-PASS (Western Pacific Air-Sea interaction Study) project has been funded for 5 years as a part of SOLAS-Japan activity in the summer of 2006. We aim to resolve air-sea interaction through field observation studies mainly using research vessels and island observatories over the western Pacific. We have carried out 5 cruises to the western North Pacific focusing on air-sea interactions. Also, an intensive marine atmospheric observation including direct atmospheric deposition measurement was accomplished by a dozen W-PASS research groups at the NIES Atmospheric and Aerosol Monitoring Station of Cape Hedo in the northernmost tip of the Okinawa main Island facing the East China Sea in the spring 2008. A few weak Kosa (dust) events, anthropogenic air outflows, typical local air and occupation of marine background air were identified during the campaign period. The W-PASS has four research groups mainly focusing on VOC emissions, air-sea gas exchange processes, biogeochemical responses to dust depositions and its modeling. We also

  12. Development of design information for molecular-sieve type regenerative CO2-removal systems

    NASA Technical Reports Server (NTRS)

    Wright, R. M.; Ruder, J. M.; Dunn, V. B.; Hwang, K. C.

    1973-01-01

    Experimental and analytic studies were conducted with molecular sieve sorbents to provide basic design information, and to develop a system design technique for regenerable CO2-removal systems for manned spacecraft. Single sorbate equilibrium data were obtained over a wide range of conditions for CO2, water, nitrogen, and oxygen on several molecular sieve and silica gel sorbents. The coadsorption of CO2 with water preloads, and with oxygen and nitrogen was experimentally evaluated. Mass-transfer, and some limited heat-transfer performance evaluations were accomplished under representative operating conditions, including the coadsorption of CO2 and water. CO2-removal system performance prediction capability was derived.

  13. Changing controls on oceanic radiocarbon: New insights on shallow-to-deep ocean exchange and anthropogenic CO2 uptake

    NASA Astrophysics Data System (ADS)

    Graven, H. D.; Gruber, N.; Key, R.; Khatiwala, S.; Giraud, X.

    2012-10-01

    The injection of radiocarbon (14C) into the atmosphere by nuclear weapons testing in the 1950s and 1960s has provided a powerful tracer to investigate ocean physical and chemical processes. While the oceanic uptake of bomb-derived 14C was primarily controlled by air-sea exchange in the early decades after the bomb spike, we demonstrate that changes in oceanic 14C are now primarily controlled by shallow-to-deep ocean exchange, i.e., the same mechanism that governs anthropogenic CO2 uptake. This is a result of accumulated bomb 14C uptake that has rapidly decreased the air-sea gradient of 14C/C (Δ14C) and shifted the main reservoir of bomb 14C from the atmosphere to the upper ocean. The air-sea Δ14C gradient, reduced further by fossil fuel dilution, is now weaker than before weapons testing in most regions. Oceanic 14C, and particularly its temporal change, can now be used to study the oceanic uptake of anthropogenic CO2. We examine observed changes in oceanic Δ14C between the WOCE/SAVE (1988-1995) and the CLIVAR (2001-2007) eras and simulations with two ocean general circulation models, the Community Climate System Model (CCSM) and the Estimating the Circulation and Climate of the Ocean Model (ECCO). Observed oceanic Δ14C and its changes between the 1980s-90s and 2000s indicate that shallow-to-deep exchange is too efficient in ECCO and too sluggish in CCSM. These findings suggest that mean global oceanic uptake of anthropogenic CO2 between 1990 and 2007 is bounded by the ECCO-based estimate of 2.3 Pg C yr-1 and the CCSM-based estimate of 1.7 Pg C yr-1.

  14. The Air-Sea Interface and Surface Stress under Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Soloviev, Alexander; Lukas, Roger; Donelan, Mark; Ginis, Isaac

    2013-04-01

    Air-sea interaction dramatically changes from moderate to very high wind speed conditions (Donelan et al. 2004). Unresolved physics of the air-sea interface are one of the weakest components in tropical cyclone prediction models. Rapid disruption of the air-water interface under very high wind speed conditions was reported in laboratory experiments (Koga 1981) and numerical simulations (Soloviev et al. 2012), which resembled the Kelvin-Helmholtz instability at an interface with very large density difference. Kelly (1965) demonstrated that the KH instability at the air-sea interface can develop through parametric amplification of waves. Farrell and Ioannou (2008) showed that gustiness results in the parametric KH instability of the air-sea interface, while the gusts are due to interacting waves and turbulence. The stochastic forcing enters multiplicatively in this theory and produces an exponential wave growth, augmenting the growth from the Miles (1959) theory as the turbulence level increases. Here we complement this concept by adding the effect of the two-phase environment near the mean interface, which introduces additional viscosity in the system (turning it into a rheological system). The two-phase environment includes air-bubbles and re-entering spray (spume), which eliminates a portion of the wind-wave wavenumber spectrum that is responsible for a substantial part of the air sea drag coefficient. The previously developed KH-type interfacial parameterization (Soloviev and Lukas 2010) is unified with two versions of the wave growth model. The unified parameterization in both cases exhibits the increase of the drag coefficient with wind speed until approximately 30 m/s. Above this wind speed threshold, the drag coefficient either nearly levels off or even slightly drops (for the wave growth model that accounts for the shear) and then starts again increasing above approximately 65 m/s wind speed. Remarkably, the unified parameterization reveals a local minimum

  15. Spatiotemporal variations in CO2 flux in a fringing reef simulated using a novel carbonate system dynamics model

    NASA Astrophysics Data System (ADS)

    Watanabe, A.; Yamamoto, T.; Nadaoka, K.; Maeda, Y.; Miyajima, T.; Tanaka, Y.; Blanco, A. C.

    2013-03-01

    A carbonate system dynamics (CSD) model was developed in a fringing reef on the east coast of Ishigaki Island, southwest Japan, by incorporating organic and inorganic carbon fluxes (photosynthesis and calcification), air-sea gas exchanges, and benthic cover of coral and seagrass into a three-dimensional hydrodynamic model. The CSD model could reproduce temporal variations in dissolved inorganic carbon (DIC) and total alkalinity in coral zones, but not in seagrass meadows. The poor reproduction in seagrass meadows can be attributed to significant contributions of submarine groundwater discharge as well as misclassification of remotely sensed megabenthos in this area. In comparison with offshore areas, the reef acted as a CO2 sink during the observation period when it was averaged over 24 h. The CSD model also indicated large spatiotemporal differences in the carbon dioxide (CO2) sink/source, possibly related to hydrodynamic features such as effective offshore seawater exchange and neap/spring tidal variation. This suggests that the data obtained from a single point observation may lead to misinterpretation of the overall trend and thus should be carefully considered. The model analysis also showed that the advective flux of DIC from neighboring grids is several times greater than local biological flux of DIC and is three orders of magnitude greater than the air-sea gas flux at the coral zone. Sensitivity tests in which coral or seagrass covers were altered revealed that the CO2 sink potential was much more sensitive to changes in coral cover than seagrass cover.

  16. The reactivity of CO2 with K atoms adsorbed on MgO powders.

    PubMed

    Preda, Gloria; Pacchioni, Gianfranco; Chiesa, Mario; Giamello, Elio

    2009-10-01

    In this combined quantum chemical and EPR study we have investigated the formation of CO(2)(-) radicals by contact of CO(2) molecules with a K precovered MgO surface. K atoms have been deposited on polycrystalline MgO samples, and then exposed to CO(2). The typical EPR signal of the isolated K atoms disappears when the reaction with CO(2) takes place and a new paramagnetic species attributed to CO(2)(-) is observed. DFT cluster model calculations show that there is a spontaneous electron transfer from the adsorbed K atom to the CO(2) molecule, with formation of K(+)CO(2)(-) surface complexes. These species have the same electronic characteristics and spin distribution of gas-phase M(+)CO(2)(-) (M = Li, Na, K) molecules, but are stabilized by the presence of the ionic surface. The most stable MgO sites where the adsorption of CO(2) occurs and the computed EPR properties are discussed.

  17. CO2 Acquisition Membrane (CAM)

    NASA Technical Reports Server (NTRS)

    Mason, Larry W.; Way, J. Douglas; Vlasse, Marcus

    2003-01-01

    The objective of CAM is to develop, test, and analyze thin film membrane materials for separation and purification of carbon dioxide (CO2) from mixtures of gases, such as those found in the Martian atmosphere. The membranes are targeted toward In Situ Resource Utilization (ISRU) applications that will operate in extraterrestrial environments and support future unmanned and human space missions. A primary application is the Sabatier Electrolysis process that uses Mars atmosphere CO2 as raw material for producing water, oxygen, and methane for rocket fuel and habitat support. Other applications include use as an inlet filter to collect and concentrate Mars atmospheric argon and nitrogen gases for habitat pressurization, and to remove CO2 from breathing gases in Closed Environment Life Support Systems (CELSS). CAM membrane materials include crystalline faujasite (FAU) zeolite and rubbery polymers such as silicone rubber (PDMS) that have been shown in the literature and via molecular simulation to favor adsorption and permeation of CO2 over nitrogen and argon. Pure gas permeation tests using commercial PDMS membranes have shown that both CO2 permeance and the separation factor relative to other gases increase as the temperature decreases, and low (Delta)P(Sub CO2) favors higher separation factors. The ideal CO2/N2 separation factor increases from 7.5 to 17.5 as temperature decreases from 22 C to -30 C. For gas mixtures containing CO2, N2, and Ar, plasticization decreased the separation factors from 4.5 to 6 over the same temperature range. We currently synthesize and test our own Na(+) FAU zeolite membranes using standard formulations and secondary growth methods on porous alumina. Preliminary tests with a Na(+) FAU membrane at 22 C show a He/SF6 ideal separation factor of 62, exceeding the Knudsen diffusion selectivity by an order of magnitude. This shows that the membrane is relatively free from large defects and associated non-selective (viscous flow) transport

  18. The seasonal cycle as a mode to diagnose biases in modelled CO2 fluxes in the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Mongwe, N. Precious; Chang, Nicolette; Monteiro, Pedro M. S.

    2016-10-01

    The Southern Ocean forms a key component of the global carbon budget, taking up about 1.0 Pg C yr-1 of anthropogenic CO2 emitted annually (∼10.7 ± 0.5 Pg C yr-1 for 2012). However, despite its importance, it still remains undersampled with respect to surface ocean carbon flux variability, resulting in weak constraints for ocean carbon and carbon - climate models. As a result, atmospheric inversion and coupled physics-biogeochemical ocean models still play a central role in constraining the air-sea CO2 fluxes in the Southern Ocean. A recent synthesis study (Lenton et al., 2013a), however, showed that although ocean biogeochemical models (OBGMs) agree on the mean annual flux of CO2 in the Southern Ocean, they disagree on both amplitude and phasing of the seasonal cycle and compare poorly to observations. In this study, we develop and present a methodological framework to diagnose the controls on the seasonal variability of sea-air CO2 fluxes in model outputs relative to observations. We test this framework by comparing the NEMO-PISCES ocean model ORCA2-LIM2-PISCES to the Takahashi 2009 (T09) CO2 dataset. Here we demonstrate that the seasonal cycle anomaly for CO2 fluxes in ORCA2LP is linked to an underestimation of winter convective CO2 entrainment as well as the impact of biological CO2 uptake during the spring-summer season, relative to T09 observations. This resulted in sea surface temperature (SST) becoming the dominant driver of seasonal scale of the partial pressure of CO2 (pCO2) variability and hence of the differences in the seasonality of CO2 sea-air flux between the model and observations.

  19. On the relations between the oceanic uptake of CO2 and its carbon isotopes

    NASA Astrophysics Data System (ADS)

    Heimann, Martin; Maier-Reimer, Ernst

    1996-03-01

    The recent proposals to estimate the oceanic uptake of CO2 by monitoring the oceanic change in 13C/12C isotope ratio [Quay et al., 1992] or the air-sea 13C/12C isotopic disequilibrium [Tans et al., 1993] is reviewed. Because the history of atmospheric CO2 and 13CO2 since preindustrial times is almost the same and increasing in an almost exponential fashion, the oceanic penetration depth of both tracers must be the same. This dynamic constraint permits the establishment of yet a third method to estimate the global ocean uptake of CO2 from 13C measurements. Using available observations in conjunction with canonical values for global carbon cycle parameters, the three methods yield inconsistent oceanic CO2 uptake rates for the time period 1970-1990, ranging from 0.6 to 3.1 GtC yr-1. However, uncertainties in the available carbon cycle data must be taken into account. Using a nonlinear estimation procedure, a consistent scenario with an oceanic CO2 uptake rate of 2.1±0.9 GtC yr-1 can be established. The method also permits an investigation of the sensitivities of the different approaches. An analysis of the results of two three-dimensional simulations with the Hamburg model of the oceanic carbon cycle shows that the 13C isotope indeed tracks the oceanic penetration of anthropogenic CO2. Because of its different time history, bomb produced radiocarbon, as measured at the time of the Geochemical Ocean Sections Study (GEOSECS), correlates not as well to excess carbon.

  20. Observations From the Coupled Boundary Layer Air-Sea Transfer Experiment in Hurricanes

    NASA Astrophysics Data System (ADS)

    Black, P. G.

    2006-12-01

    The CBLAST field program conducted from 2002-2004 has shown that the wind speed range for which turbulent momentum and moisture exchange coefficients have been derived based upon direct flux measurements has been extended by 30 and 60 percent, respectively, from airborne observations in Hurricanes Fabian and Isabel in 2003. The drag coefficient (CD) values derived from CBLAST momentum flux measurements show CD becoming invariant with wind speed near a 23 ms-1 threshold rather than a hurricane-force threshold near 33 ms-1. Values above 23 ms-1 are lower than previous open ocean measurements. The Dalton number estimates (CE) derived from CBLAST moisture flux measurements are shown to be invariant with wind speed to 30 ms-1, in approximate agreement with previous measurements at lower winds. These observations imply a CE/CD ratio of approximately 0.7, suggesting that additional energy sources are necessary for hurricanes to achieve their maximum potential intensity. Two such additional mechanisms for augmented moisture flux in the boundary layer might be 1) augmented wave breaking by short-crested, fetch limited waves suggested by whitecap aerial coverage measurements, and 2) sea spray at high winds suggested by laboratory spray source function measurements. Linear coherent features in the hurricane boundary layer are a third mechanism, observed during CBLAST 2002 aircraft measurements, to have wavelengths of 0.9 to 1.2 km. Linear features of the same wavelength range were observed in nearly-concurrent RADARSAT Synthetic Aperture Radar (SAR) imagery. Arrays of drifting buoys and subsurface floats were successfully deployed ahead of Hurricanes Fabian (2003) and Frances (2004): 16 (6) and 38 (14) drifters (floats). Two types of surface drifters and three types of floats provided observations of surface and subsurface oceanic currents, temperature, salinity, gas exchange, bubble concentrations and surface wave spectra to a depth of 200 m on a continuous basis before, during and after storm passage. Float observations indicated deepening of the mixed layer from 40 to 120 m in approximately 8 hr with a corresponding decrease in SST in the right-rear quadrant of 3.2 ºC in 11 hr, roughly one-half inertial period. Strong inertial currents with a peak amplitude of 1.5 ms-1 were observed. Vertical structure showed the critical Richardson number was reached sporadically during the mixed-layer deepening event, suggesting shear-induced mixing as a prominent mechanism during storm passage.

  1. pCO2 distributions and air-water CO2 fluxes in the Columbia River estuary

    NASA Astrophysics Data System (ADS)

    Evans, Wiley; Hales, Burke; Strutton, Peter G.

    2013-01-01

    Sources of time and space variability in the distributions of surface water carbon dioxide partial pressure (pCO2) and air-water CO2 flux were quantified in the Columbia River estuary (CRE) during five cruises in spring, summer and autumn 2007/08. The CRE is an upwelling margin river-dominated mesotidal system that is an estuary class not represented in global flux compilations. Data from the CRE show instances of pCO2 under and oversaturation with respect to the atmosphere during every season in association with tidal, wind, biological and storm-driven sources of variability. On average the CRE is a sink for atmospheric CO2 during spring and a source during summer and autumn, with large positive air-water CO2 fluxes during the snowmelt freshet coinciding with the functional transition in the estuary. It is hypothesized here that interannual variability in size of the snowmelt freshet largely influences the extent of springtime CO2 uptake in the CRE, and subsequently the magnitude of net annual CO2 emission from the estuary. Data collected during an autumn storm show that large fluxes can drop quickly, even in the presence of high gas transfer velocities, because of rapid CO2 exchange with the atmosphere in this weakly buffered system. Combining seasonal observations of CO2 exchange with an assumption of winter conditions, we estimate that the net annual emission from the CRE is approximately 1 mol C m-2 yr-1. The air-water CO2 fluxes reported here are the first from an upwelling margin river-dominated mesotidal estuary, and the estimate of net annual exchange is substantially lower than those from other tidal and/or large river systems represented in global flux compilations.

  2. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Calculation of mass transfer in the remote cutting of metals by radiation of a high-power repetitively pulsed CO2 laser

    NASA Astrophysics Data System (ADS)

    Gladush, G. G.; Rodionov, N. B.

    2002-01-01

    The mechanism of remote cutting of steel plates by radiation of a high-power repetitively pulsed CO2 laser is theoretically studied. The models of melt removal by the gravity force and the recoil pressure of material vapour are proposed and the sufficient conditions for the initiation of cutting are determined. A numerical model of a thermally thin plate was employed to describe the cutting for large focal spots.

  3. Bubble Stripping as a Tool To Reduce High Dissolved CO2 in Coastal Marine Ecosystems.

    PubMed

    Koweek, David A; Mucciarone, David A; Dunbar, Robert B

    2016-04-05

    High dissolved CO2 concentrations in coastal ecosystems are a common occurrence due to a combination of large ecosystem metabolism, shallow water, and long residence times. Many important coastal species may have adapted to this natural variability over time, but eutrophication and ocean acidification may be perturbing the water chemistry beyond the bounds of tolerance for these organisms. We are currently limited in our ability to deal with the geochemical changes unfolding in our coastal ocean. This study helps to address this deficit of solutions by introducing bubble stripping as a novel geochemical engineering approach to reducing high CO2 in coastal marine ecosystems. We use a process-based model to find that air/sea gas exchange rates within a bubbled system are 1-2 orders of magnitude higher than within a nonbubbled system. By coupling bubbling-enhanced ventilation to a coastal ecosystem metabolism model, we demonstrate that strategically timed bubble plumes can mitigate exposure to high CO2 under present-day conditions and that exposure mitigation is enhanced in the more acidic conditions predicted by the end of the century. We argue that shallow water CO2 bubble stripping should be considered among the growing list of engineering approaches intended to increase coastal resilience in a changing ocean.

  4. Estimation of continuous anthropogenic CO2 using CO2, CO, δ13C(CO2) and Δ14C(CO2)

    NASA Astrophysics Data System (ADS)

    Vardag, S. N.; Gerbig, C.; Janssens-Maenhout, G.; Levin, I.

    2015-07-01

    We investigate different methods for estimating anthropogenic CO2 using modelled continuous atmospheric concentrations of CO2 alone, as well as CO2 in combination with the surrogate tracers CO, δ13C(CO2) and Δ14C(CO2). These methods are applied at three hypothetical stations representing rural, urban and polluted conditions. We find that independent of the tracer used, an observation-based estimate of continuous anthropogenic CO2 is not feasible at rural measurement sites due to the low signal to noise ratio of anthropogenic CO2 estimates at such settings. At urban and polluted sites, potential future continuous Δ14C(CO2) measurements with a precision of 5 ‰ or better are most promising for anthropogenic CO2 determination (precision ca. 10-20%), but the insensitivity against CO2 contributions from biofuel emissions may reduce its accuracy in the future. Other tracers, such as δ13C(CO2) and CO could provide an accurate and already available alternative if all CO2 sources in the catchment area are well characterized with respect to their isotopic signature and CO to anthropogenic CO2 ratio. We suggest a strategy for calibrating these source characteristics on an annual basis using precise Δ14C(CO2) measurements on grab samples. The precision of anthropogenic CO2 determination using δ13C(CO2) is largely determined by the measurement precision of δ13C(CO2) and CO2. The precision when using the CO-method is mainly limited by the variation of natural CO sources and CO sinks. At present, continuous anthropogenic CO2 could be determined using the tracers δ13C(CO2) and/or CO with a precision of about 30 %, a mean bias of about 10 % and without significant diurnal discrepancies. This allows significant improvement, validation and bias reduction of highly resolved emission inventories using atmospheric observation and regional modelling.

  5. Surface Condensation of CO2 onto Kaolinite

    SciTech Connect

    Schaef, Herbert T.; Glezakou, Vassiliki Alexandra; Owen, Antionette T.; Ramprasad, Sudhir; Martin, Paul F.; McGrail, B. Peter

    2014-02-11

    The fundamental adsorption behavior of gaseous and supercritical carbon dioxide (CO2) onto poorly crystalline kaolinite (KGa-2) at conditions relevant to geologic sequestration has been investigated using a quartz crystal microbalance (QCM) and density functional theory (DFT) methods. The QCM data indicated linear adsorption of CO2 (0-0.3 mmol CO2/g KGa-2) onto the kaolinite surface up through the gaseous state (0.186 g/cm3). However in the supercritical region, CO2 adsorption increases dramatically, reaching a peak (0.9-1.0 mmol CO2/g KGa-2) near 0.43 g/cm3, before declining rapidly to surface adsorption values equivalent or below gaseous CO2. This adsorption profile was not observed with He or N2. Comparative density functional studies of CO2 interactions with kaolinite surface models rule out CO2 intercalation and confirm that surface adsorption is favored up to approximately 0.35 g/cm3 of CO2, showing distorted T-shaped CO2-CO2 clustering, typical of supercritical CO2 aggregation over the surface as the density increases. Beyond this point, the adsorption energy gain for any additional CO2 becomes less than the CO2 interaction energy (~0.2 eV) in the supercritical medium resulting in overall desorption of CO2 from the kaolinite surface.

  6. Outsourcing CO2 within China

    PubMed Central

    Feng, Kuishuang; Davis, Steven J.; Sun, Laixiang; Li, Xin; Guan, Dabo; Liu, Weidong; Liu, Zhu; Hubacek, Klaus

    2013-01-01

    Recent studies have shown that the high standard of living enjoyed by people in the richest countries often comes at the expense of CO2 emissions produced with technologies of low efficiency in less affluent, developing countries. Less apparent is that this relationship between developed and developing can exist within a single country’s borders, with rich regions consuming and exporting high-value goods and services that depend upon production of low-cost and emission-intensive goods and services from poorer regions in the same country. As the world’s largest emitter of CO2, China is a prominent and important example, struggling to balance rapid economic growth and environmental sustainability across provinces that are in very different stages of development. In this study, we track CO2 emissions embodied in products traded among Chinese provinces and internationally. We find that 57% of China’s emissions are related to goods that are consumed outside of the province where they are produced. For instance, up to 80% of the emissions related to goods consumed in the highly developed coastal provinces are imported from less developed provinces in central and western China where many low–value-added but high–carbon-intensive goods are produced. Without policy attention to this sort of interprovincial carbon leakage, the less developed provinces will struggle to meet their emissions intensity targets, whereas the more developed provinces might achieve their own targets by further outsourcing. Consumption-based accounting of emissions can thus inform effective and equitable climate policy within China. PMID:23754377

  7. Impacts of air-sea exchange coefficients on snowfall events over the Korean Peninsula

    NASA Astrophysics Data System (ADS)

    Kang, Jung-Yoon; Kwon, Young Cheol

    2016-08-01

    Snowfall over the Korean Peninsula is mainly associated with air mass transformation by the fluxes across the air-sea interface during cold-air outbreaks over the warm Yellow Sea. The heat and momentum exchange coefficients in the surface flux parameterization are key parameters of flux calculations across the air-sea interface. This study investigates the effects of the air-sea exchange coefficients on the simulations of snowfall events over the Korean Peninsula using the Weather Research and Forecasting (WRF) model. Two snowfall cases are selected for this study. One is a heavy snowfall event that took place on January 4, 2010, and the other is a light snowfall event that occurred on December 23-24, 2011. Several sensitivity tests are carried out with increased and decreased heat and momentum exchange coefficients. The domain-averaged precipitation is increased (decreased) with increased (decreased) heat exchange coefficient because the increased (decreased) surface heat flux leads to more (less) moist conditions in the low level of the atmosphere. On the other hand, the domain-averaged precipitation is decreased (increased) with increased (decreased) momentum exchange coefficient because the increased (decreased) momentum coefficient causes reduction (increase) of wind speed and heat flux. The variation of precipitation in the heat exchange coefficient experiments is much larger than that in the momentum exchange coefficient experiments because the change of heat flux has a more direct impact on moisture flux and snowfall amount, while the change of momentum flux has a rather indirect impact via wind speed changes. The low-pressure system is intensified and moves toward North when the heat exchange coefficient is increased because warming and moistening of the lower atmosphere contributes to destabilize the air mass, resulting in the change of precipitation pattern over the Korean Peninsula in the heat exchange coefficient experiments.

  8. Predicting the Turbulent Air-Sea Surface Fluxes, Including Spray Effects, from Weak to Strong Winds

    DTIC Science & Technology

    2012-09-30

    from Moon et al. (2007) and Mueller and Veron (2009) are not much different from our main straight-line result (6) for UN10 above 20 m/s...model the air-sea drag as a consequence of just wind-wave coupling. That is, Moon et al. (2007) and Mueller and Veron (2009) modeled the surface stress... Veron evidently realized that they were predicting u* to be a linear function of UN10 in high winds.) In other words, exotic processes like sea

  9. Phytoplankton carbon fixation gene (RuBisCO) transcripts and air-sea CO2 flux in the Mississippi River plume

    SciTech Connect

    John, David E.; Wang, Zhaohui A.; Liu, Xuewu; Byrne, Robert H.; Corredor, Jorge E.; López, José M.; Cabrera, Alvaro; Bronk, Deborah A.; Tabita, F. Robert; Paul, John H.

    2007-08-30

    River plumes deliver large quantities of nutrients to oligotrophic oceans, often resulting in significant CO2 drawdown. To determine the relationship between expression of the major gene in carbon fixation (large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase, RuBisCO) and CO2 dynamics, we evaluated rbcL mRNA abundance using novel quantitative PCR assays, phytoplankton cell analyses, photophysiological parameters, and pCO2 in and around the Mississippi River plume (MRP) in the Gulf of Mexico. Lower salinity (30–32) stations were dominated by rbcL mRNA concentrations from heterokonts, such as diatoms and pelagophytes, which were at least an order of magnitude greater than haptophytes, alpha-Synechococcus or high-light Prochlorococcus. However, rbcL transcript abundances were similar among these groups at oligotrophic stations (salinity 34–36). Diatom cell counts and heterokont rbcL RNA showed a strong negative correlation to seawater pCO2. While Prochlorococcus cells did not exhibit a large difference between low and high pCO2 water, Prochlorococcus rbcL RNA concentrations had a strong positive correlation to pCO2, suggesting a very low level of RuBisCO RNA transcription among Prochlorococcus in the plume waters, possibly due to their relatively poor carbon concentrating mechanisms (CCMs). These results provide molecular evidence that diatom/pelagophyte productivity is largely responsible for the large CO2 drawdown occurring in the MRP, based on the co-occurrence of elevated RuBisCO gene transcript concentrations from this group and reduced seawater pCO2 levels. This may partly be due to efficient CCMs that enable heterokont eukaryotes such as diatoms to continue fixing CO2 in the face of strong CO2 drawdown. Finally, our work represents the first attempt to relate in situ microbial gene expression to contemporaneous CO2 flux measurements in the ocean.

  10. Comparison of the One-electron Oxidations of CO-Bridged vs Unbridged Bimetallic Complexes: Electron-transfer Chemistry of Os2Cp2(CO)4 and Os2Cp*2(μ-CO)2(CO)2 (Cp = η5-C5H5, Cp* = η5-C5Me5)

    SciTech Connect

    Laws, Derek R.; Bullock, R. Morris; Lee, Richmond; Huang, Kuo-Wei; Geiger, William J.

    2014-09-22

    The one-electron oxidations of two dimers of half-sandwich osmium carbonyl complexes have been examined by electrochemistry, spectro-electrochemistry, and computational methods. The all-terminal carbonyl complex Os2Cp2(CO)4 (1, Cp = η5-C5H5) undergoes a reversible one-electron anodic reaction at E1/2 = 0.41 V vs ferrocene in CH2Cl2/0.05 M [NBu4][B(C6F5)4], giving a rare example of a metal-metal bonded radical cation unsupported by bridging ligands. The IR spectrum of 1+ is consistent with an approximately 1:1 mixture of anti and gauche structures for the 33 e- radical cation in which it has retained all-terminal bonding of the CO ligands. DFT calculations, including orbital-occupancy-perturbed Mayer bond-order analyses, show that the HOMOs of anti-1 and gauche-1 are metal-ligand delocalized. Removal of an electron from 1 has very little effect on the Os-Os bond order, accounting for the resistance of 1+ to heterolytic cleavage. The Os-Os bond distance is calculated to decrease by 0.10 Å and 0.06 Å as a consequence of one-electron oxidation of anti-1 and gauche-1, respectively. The CO-bridged complex Os2Cp*2(μ-CO)2(CO)2 (Cp* = η5-C5Me5), trans-2, undergoes a more facile oxidation, E1/2 = - 0.11 V, giving a persistent radical cation shown by solution IR analysis to preserve its bridged-carbonyl structure. However, ESR analysis of frozen solutions of 2+ is interpreted in terms of the presence of two isomers, most likely anti-2+ and trans-2+, at low temperature. Calculations show that the HOMO of trans-2 is highly delocalized over the metal-ligand framework, with the bridging carbonyls accounting for about half of the orbital makeup. The Os-Os bond order again changes very little with removal of an electron, and the Os-Os bond length actually undergoes minor shortening. Calculations suggest that the second isomer of 2+ has both the trans CO-bridged and the anti all-terminal CO structures. DRL and WEG acknowledge the support of the National Science Foundation under

  11. Effects of diffusion impairment on O2 and CO2 time courses in pulmonary capillaries.

    NASA Technical Reports Server (NTRS)

    Wagner, P. D.; West, J. B.

    1972-01-01

    Simultaneous time courses for O2 and CO2 exchange along the capillary have been calculated for homogeneous lungs, allowing for O2-CO2 interactions, dissolved O2, and chemical reaction rates. As diffusing capacity (Dl) was reduced, the transfer of CO2 and O2 was impaired by similar amounts, in spite of the 20-fold greater diffusing capacity for CO2. The reason why CO2 is affected so much is that the slope of the content against partial pressure is so much greater in blood than tissue for this gas. Because of the shapes of their respective dissociation curves, O2 transfer was most affected at normal ventilation-perfusion ratios, whereas CO2 was most affected at high ratios. Exercise exaggerated the impairment of transfer of both gases.

  12. Impacts of elevated CO2 on plant-microbial interactions

    NASA Astrophysics Data System (ADS)

    Shi, S.; Herman, D.; Nuccio, E. E.; Pett-Ridge, J.; Brodie, E.; He, Z.; Zhou, J.; Firestone, M.

    2014-12-01

    Rising atmospheric CO2 levels are predicted to alter C cycling and terrestrial ecosystem functions through effects on plant-microbial interactions. Under elevated CO2, plants transfer more C belowground. However, the fate, transformation and consequence of this extra C in soil are not well understood. We examined the influence of eCO2 on the belowground C cycling using Avena fatua, a common Mediterranean annual grass, with its root associated microbial community across multiple plant growth stages over one-growing season. Avena grown under eCO2 (700 ppm) 13CO2 increased both total C allocated belowground and the amount of root-derived 13C in the mineral-associated fraction. Although eCO2 did not show any significant impact on the abundance (quantified by qPCR) and composition (assessed by MiSeq 16S and ITS sequencing) of rhizosphere microbial community at any sampling time point, small but significant shifts on rhizosphere microbial functional potential were detected using GeoChip 5.0. In addition, the rhizosphere effect (i.e., impact of roots on rhizosphere community versus bulk soil) was much stronger in plants grown under eCO2 than these under ambient CO2 (aCO2). The rhizosphere enriched genes included key functional genes involved in C, N, P and S cycling as well as stress response. The signal intensities of a number of C cycling genes shifted significantly in rhizosphere communities associated with plants grown under eCO2, and many of these genes are involved in the decomposition of low molecular weight C compounds. When plants became senescent, the abundance of some genes encoding enzymes capable of decomposing macromolecular C compounds (e.g., xylanase, endopolygalacturonase) were significant higher in the rhizosphere of Avena grown in eCO2 than aCO2 condition, which may be due to the higher amount of Avena root debris detected at the end of season. Understanding modulations of plant-microbial interactions due to changing climate may allow improved

  13. Resolving the abundance and air-sea fluxes of airborne microorganisms in the North Atlantic Ocean.

    PubMed

    Mayol, Eva; Jiménez, María A; Herndl, Gerhard J; Duarte, Carlos M; Arrieta, Jesús M

    2014-01-01

    Airborne transport of microbes may play a central role in microbial dispersal, the maintenance of diversity in aquatic systems and in meteorological processes such as cloud formation. Yet, there is almost no information about the abundance and fate of microbes over the oceans, which cover >70% of the Earth's surface and are the likely source and final destination of a large fraction of airborne microbes. We measured the abundance of microbes in the lower atmosphere over a transect covering 17° of latitude in the North Atlantic Ocean and derived estimates of air-sea exchange of microorganisms from meteorological data. The estimated load of microorganisms in the atmospheric boundary layer ranged between 6 × 10(4) and 1.6 × 10(7) microbes per m(2) of ocean, indicating a very dynamic air-sea exchange with millions of microbes leaving and entering the ocean per m(2) every day. Our results show that about 10% of the microbes detected in the boundary layer were still airborne 4 days later and that they could travel up to 11,000 km before they entered the ocean again. The size of the microbial pool hovering over the North Atlantic indicates that it could play a central role in the maintenance of microbial diversity in the surface ocean and contribute significantly to atmospheric processes.

  14. Air-Sea Spray Airborne Radar Profiler Characterizes Energy Fluxes in Hurricanes

    NASA Technical Reports Server (NTRS)

    Durden, Stephen L.; Esteban-Fermandez, D.

    2010-01-01

    A report discusses ASAP (Air-sea Spray Airborne Profiler), a dual-wavelength radar profiler that provides measurement information about the droplet size distribution (DSD) of sea-spray, which can be used to estimate heat and moisture fluxes for hurricane research. Researchers have recently determined that sea spray can have a large effect on the magnitude and distribution of the air-sea energy flux at hurricane -force wind speeds. To obtain information about the DSD, two parameters of the DSD are required; for example, overall DSD amplitude and DSD mean diameter. This requires two measurements. Two frequencies are used, with a large enough separation that the differential frequency provides size information. One frequency is 94 GHz; the other is 220 GHz. These correspond to the Rayleigh and Mie regions. Above a surface wind speed of 10 m/ s, production of sea spray grows exponentially. Both the number of large droplets and the altitude they reach are a function of the surface wind speed.

  15. Impacts of Air-Sea Interaction on Tropical Cyclone Track and Intensity

    NASA Technical Reports Server (NTRS)

    Wu, Liguang; Wang, Bin; Braun, Scott A.

    2004-01-01

    The influence of hurricane-ocean coupling on intensity and track of tropical cyclones (TCs) is investigated through idealized numerical experiments using a coupled hurricane-ocean model. The focus is placed on how air-sea interaction affects TC tracks and intensity. It is found that the symmetric sea surface temperature (SST) cooling is primarily responsible for the TC weakening in the coupled experiments because the induced asymmetric circulation associated with the asymmetric SST anomalies is weak and shallow. The track difference between the coupled and fixed SST experiments is generally small because of the competing processes. One is associated with the modified TC asymmetries. The asymmetric SST anomalies - weaken the surface fluxes in the rear and enhance the fluxes in the front. As a result, the enhanced diabatic heating is located on the southern side for a westward-moving TC, tending to shift the TC southward. The symmetric SST anomalies weakens the TC intensity and thus the dymmetrization process, leading to more prominent TC asymmetries. The other is associated with the weakening of the beta drift resulting from the weakening of the TC outer strength. In the coupled experiment, the weakening of the beta drift leads to a more northward shift. By adjusting the vortex outer strength of the initial vortices, the beta drift can vary while the effect of air-sea interaction changes little. Two types of track differences simulated in the previous numerical studies are obtained.

  16. Biopolymers form a gelatinous microlayer at the air-sea interface when Arctic sea ice melts

    PubMed Central

    Galgani, Luisa; Piontek, Judith; Engel, Anja

    2016-01-01

    The interface layer between ocean and atmosphere is only a couple of micrometers thick but plays a critical role in climate relevant processes, including the air-sea exchange of gas and heat and the emission of primary organic aerosols (POA). Recent findings suggest that low-level cloud formation above the Arctic Ocean may be linked to organic polymers produced by marine microorganisms. Sea ice harbors high amounts of polymeric substances that are produced by cells growing within the sea-ice brine. Here, we report from a research cruise to the central Arctic Ocean in 2012. Our study shows that microbial polymers accumulate at the air-sea interface when the sea ice melts. Proteinaceous compounds represented the major fraction of polymers supporting the formation of a gelatinous interface microlayer and providing a hitherto unrecognized potential source of marine POA. Our study indicates a novel link between sea ice-ocean and atmosphere that may be sensitive to climate change. PMID:27435531

  17. An airborne C-band scatterometer for remote sensing the air-sea interface

    NASA Technical Reports Server (NTRS)

    Mclaughlin, D. J.; Pazmany, A. L.; Boltniew, E.; Hevizi, L. G.; Mcintosh, R. E.

    1989-01-01

    An airborne C-band scatterometer system (C-Scat) has been developed for remote sensing of the air-sea interface. The sensor has been designed to fly on a number of research aircraft, beginning with the NASA Ames Research Center's C-130B, on which test flights were conducted in August of 1988. The scatterometer utilizes a 10-W solid-state power amplifier and a frequency-steered microstrip array antenna which is installed beneath the fuselage of the airplane. The antenna is electrically scanned in elevation from 20 to 50 deg off nadir, and it is mechanically rotated 360 deg in azimuth. The system is fully computer controlled and is capable of accurately measuring ocean-surface normalized radar cross section (NRCS) from altitudes as high as 25,000 feet. It has been developed to study the relationship between NRCS and ocean-surface roughness influences such as wind speed and direction, wave height and slope, and air-sea temperature difference.

  18. Occurrence and air-sea exchange of phthalates in the Arctic.

    PubMed

    Xie, Zhiyong; Ebinghaus, Ralf; Temme, Christian; Lohmann, Rainer; Caba, Armando; Ruck, Wolfgang

    2007-07-01

    Air and seawater samples were taken simultaneously to investigate the distribution and air-sea gas exchange of phthalates in the Arctic onboard the German Research Ship FS Polarstern. Samples were collected on expeditions ARK XX1&2 from the North Sea to the high Arctic (60 degrees N-85 degrees N) in the summer of 2004. The concentration of sigma6 phthalates (dimethyl phthalate (DMP), diethyl phthalate (DEP), di-i-butyl phthalate (DiBP), di-n-butyl phthalate (DnBP), butylbenzyl phthalate (BBP), and diethylhexyl phthalate (DEHP)) ranged from 30 to 5030 pg L(-1) in the aqueous dissolved phase and from 1110 to 3090 pg m(-3) in the atmospheric gas phase. A decreasing latitudinal trend was present in the seawater and to a lesser degree in the atmosphere from the Norwegian coast to the high Arctic. Overall, deposition dominated the air-sea gas exchange for DEHP, while volatilization from seawater took place in the near-coast environment. The estimated net gas deposition of DEHP was 5, 30, and 190 t year(-1) for the Norwegian Sea, the Greenland Sea, and the Arctic, respectively. This suggests that atmospheric transport and deposition of phthalates is a significant process for their occurrence in the remote Atlantic and Arctic Ocean.

  19. CO 2-water-basalt interaction. Numerical simulation of low temperature CO 2 sequestration into basalts

    NASA Astrophysics Data System (ADS)

    Gysi, Alexander P.; Stefánsson, Andri

    2011-09-01

    The interaction between CO 2-rich waters and basaltic glass was studied using reaction path modeling in order to get insight into the water-rock reaction process including secondary mineral composition, water chemistry and mass transfer as a function of CO 2 concentration and reaction progress ( ξ). The calculations were carried out at 25-90 °C and pCO 2 to 30 bars and the results were compared to recent experimental observations and natural systems. A thermodynamic dataset was compiled from 25 to 300 °C in order to simulate mineral saturations relevant to basalt alteration in CO 2-rich environment including revised key aqueous species for mineral dissolution reactions and apparent Gibbs energies for clay and carbonate solid solutions observed to form in nature. The dissolution of basaltic glass in CO 2-rich waters was found to be incongruent with the overall water composition and secondary mineral formation depending on reaction progress and pH. Under mildly acid conditions in CO 2 enriched waters (pH <6.5), SiO 2 and simple Al-Si minerals, Ca-Mg-Fe smectites and Ca-Mg-Fe carbonates predominated. Iron, Al and Si were immobile whereas the Mg and Ca mobility depended on the mass of carbonate formed and water pH. Upon quantitative CO 2 mineralization, the pH increased to >8 resulting in Ca-Mg-Fe smectite, zeolites and calcite formation, reducing the mobility of most dissolved elements. The dominant factor determining the reaction path of basalt alteration and the associated element mobility was the pH of the water. In turn, the pH value was determined by the concentration of CO 2 and extent of reaction. The composition of the carbonates depended on the mobility of Ca, Mg and Fe. At pH <6.5, Fe was in the ferrous oxidation state resulting in the formation of Fe-rich carbonates with the incorporation of Ca and Mg. At pH >8, the mobility of Fe and Mg was limited due to the formation of clays whereas Ca was incorporated into calcite, zeolites and clays. Competing

  20. Air-sea exchange of dimethylsulfide in the Southern Ocean: Measurements from SO GasEx compared to temperate and tropical regions

    NASA Astrophysics Data System (ADS)

    Yang, M.; Blomquist, B. W.; Fairall, C. W.; Archer, S. D.; Huebert, B. J.

    2011-04-01

    In the Southern Ocean Gas Exchange Experiment (SO GasEx), we measured an atmospheric dimethylsulfide (DMS) concentration of 118 ± 54 pptv (1σ), a DMS sea-to-air flux of 2.9 ± 2.1 μmol m-2 d-1 by eddy covariance, and a seawater DMS concentration of 1.6 ± 0.7 nM. Dividing flux by the concurrent air-sea concentration difference yields the transfer velocity of DMS (kDMS). The kDMS in the Southern Ocean was significantly lower than previous measurements in the equatorial east Pacific, Sargasso Sea, northeast Atlantic, and southeast Pacific. Normalizing kDMS for the temperature dependence in waterside diffusivity and solubility results in better agreement among various field studies and suggests that the low kDMS in the Southern Ocean is primarily due to colder temperatures. The higher solubility of DMS at a lower temperature results in greater airside control and less transfer of the gas by bubbles formed from breaking waves. The final normalized DMS transfer velocity is similar to k of less soluble gases such as carbon dioxide in low-to-moderate winds; in high winds, DMS transfer velocity is significantly lower because of the reduced bubble-mediated transfer.

  1. Lasers utilizing CO2 isotopes

    NASA Astrophysics Data System (ADS)

    Pechenin, Yu V.; Domanov, M. S.

    1980-08-01

    The lasing spectra and energy characteristics were investigated for lasers operating with the isotopes 12C16O2, 13C16O2, 12C18O2, and 12C16O18O. It was found that the output power of a laser utilizing the CO2 isotopes was determined by the content of a particular isotope in the carbon dioxide gas. For equal enrichments, all the isotopes investigated, with the exception of 12C16O18O, gave comparable output powers. The unsaturated gains were identical for the most intense transitions of the symmetric molecules; the gain was a factor of two less for the asymmetric molecule. The gain rose linearly with increasing enrichment. The ultimate specific power output, given by the product of the saturation power density and the gain, was practically independent of the enrichment.

  2. Atmospheric CO2 balance: The role of Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Semiletov, Igor; Makshtas, Alexander; Akasofu, Syun-Ichi; Andreas, Edgar L.

    2004-03-01

    Climatic changes in the Northern Hemisphere have led to remarkable environmental changes in the Arctic Ocean, including significant shrinking of sea-ice cover in summer, increased time between sea-ice break-up and freeze-up, and Arctic surface water freshening and warming associated with melting sea-ice, thawing permafrost, and increased runoff [Carmack, 2000; Morison et al., 2000; Semiletov et al., 2000; Serreze et al., 2000]. These changes are commonly attributed to the greenhouse effect resulting from increased carbon dioxide (CO2) concentration. The greenhouse effect should be most pronounced in the Arctic where the largest air CO2 concentrations and winter-summer variations in the world for a clean background environment were detected [Conway et al., 1994; Climate Monitoring and Diagnostics Laboratory Data Archive, http://www.cmdl.noaa.gov/info/ftpdata.html]. Some increased seasonal variation may be a consequence of increasing summer CO2 assimilation by plants in response to higher temperature and longer growing season [Keeling et al., 1996]. Here we show that sea-ice melt ponds and open brine channels form an important spring/summer air CO2 sink that also must be included in any Arctic regional CO2 budget; both the direction and amount of CO2 transfer between air and sea during the open water season may be different from transfer during freezing and thawing, or during winter when CO2 accumulates beneath Arctic sea-ice.

  3. Development and application of gravity-capillary wave fourier analysis for the study of air-sea interaction physics

    NASA Astrophysics Data System (ADS)

    MacKenzie Laxague, Nathan Jean

    short ocean surface waves to atmospheric forcing. Another is the exploration of long wave-short wave interactions and their effects on air-sea interaction vis-a-vis hydrodynamic modulation. The third and final topic is the characterization of the gravity-capillary regime of the wavenumber-frequency spectrum for the purpose of retrieving near-surface, wind-driven current. All of these fit as part of the desire to more fully describe the mechanism by which momentum is transferred across the air-sea interface and to discuss the consequences of this flux in the very near-surface layer of the ocean. Gravity-capillary waves are found to have an outsize share of ocean surface roughness, with short wave spectral peaks showing a connection to turbulent atmospheric stress. Short wave modulation is found to occur strongest at high wavenumbers at the lowest wind speeds, with peak modulation occurring immediately downwind of the long wave crest. Furthermore, short scale roughness enhancement is found to occur upwind of the long wave crest for increasing wind forcing magnitude. Observations of the near-surface current profile show that flows retrieved via this method agree well with the results of camera-tracked dye. Application of this method to data collected in the mouth of the Columbia River (MCR) indicates the presence of a near-surface current component that departs considerably from the tidal flow and orients into the wind stress direction. These observations demonstrate that wind speed-based parameterizations may not be sufficient to estimate wind drift and hold implications for the way in which surface material (e.g., debris or spilled oil) transport is estimated when atmospheric stress is of relatively high magnitude or is steered off the mean wind direction.

  4. Exploring the influence of surface waves in the carbon dioxide transfer velocity between the ocean and atmosphere in the coastal region

    NASA Astrophysics Data System (ADS)

    Ocampo-Torres, Francisco Javier; Francisco Herrera, Carlos; Gutiérrez-Loza, Lucía; Osuna, Pedro

    2016-04-01

    Field measurements have been carried out in order to better understand the possible influence of ocean surface waves in the transfer of carbon dioxide between the ocean and atmosphere in the coastal zone. The CO2 fluxes are being analysed and results are shown in a contribution by Gutiérrez-Loza et al., in this session. Here we try to highlight the findings regarding the transfer velocity (kCO2) once we have incorporated direct measurements of carbon dioxide concentration in the water side. In this study direct measurements of CO2 fluxes were obtained with an eddy covariance tower located in the shoreline equipped with an infrared open-path gas analyzer (LI-7500, LI-COR) and a sonic anemometer (R3-100 Professional Anemometer, Gill Instruments), both at about 13 m above the mean sea level, and sampling at 20 Hz. For some period of time simultaneous information of waves was recorded with a sampling rate of 2 Hz using an Acoustic Doppler Current Profiler (Workhorse Sentinel, Teledyne RD Instruments) at 10 m depth and 350 m away from the tower. Besides, recently the concentration of CO2 in water has also been recorded making use of a SAMI-CO2 instrument. A subtle effect of the wave field is detected in the estimated kCO2. Looking into details of the surface currents being detected very near the air-sea interface through an ADPC, a certain association can be found with the gas transfer velocity. Furthermore, some of the possible effects of breaking wave induced turbulence in the coastal zone is to be addressed. This work represents a RugDiSMar Project (CONACYT 155793) contribution. The support from CB-2011-01-168173 CONACYT project is greatly acknowledged.

  5. 76 FR 15249 - Deferral for CO2

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-21

    ... area of land. Carbon can cycle fairly rapidly back to the atmosphere or it can remain stored on land... Deterioration (PSD) and Title V permitting requirements to biogenic carbon dioxide (CO 2 ) emissions from... Information CFR Code of Federal Regulations CH 4 methane CO 2 Carbon dioxide CO 2 e Carbon dioxide...

  6. Simultaneous Online Measurement of H2O and CO2 in the Humid CO2 Adsorption/Desorption Process.

    PubMed

    Yu, Qingni; Ye, Sha; Zhu, Jingke; Lei, Lecheng; Yang, Bin

    2015-01-01

    A dew point meter (DP) and an infrared (IR) CO2 analyzer were assembled in a humid CO2 adsorption/desorption system in series for simultaneous online measurements of H2O and CO2, respectively. The humidifier, by using surface-flushing on a saturated brine solution was self-made for the generation of humid air flow. It was found that by this method it became relatively easy to obtain a low H2O content in air flow and that its fluctuation could be reduced compared to the bubbling method. Water calibration for the DP-IR detector is necessary to be conducted for minimizing the measurement error of H2O. It demonstrated that the relative error (RA) for simultaneous online measurements H2O and CO2 in the desorption process is lower than 0.1%. The high RA in the adsorption of H2O is attributed to H2O adsorption on the transfer pipe and amplification of the measurement error. The high accuracy of simultaneous online measurements of H2O and CO2 is promising for investigating their co-adsorption/desorption behaviors, especially for direct CO2 capture from ambient air.

  7. Antimicrobial Activities of Methanol, Ethanol and Supercritical CO2 Extracts of Philippine Piper betle L. on Clinical Isolates of Gram Positive and Gram Negative Bacteria with Transferable Multiple Drug Resistance.

    PubMed

    Valle, Demetrio L; Cabrera, Esperanza C; Puzon, Juliana Janet M; Rivera, Windell L

    2016-01-01

    Piper betle L. has traditionally been used in alternative medicine in different countries for various therapeutic purposes, including as an anti-infective agent. However, studies reported in the literature are mainly on its activities on drug susceptible bacterial strains. This study determined the antimicrobial activities of its ethanol, methanol, and supercritical CO2 extracts on clinical isolates of multiple drug resistant bacteria which have been identified by the Infectious Disease Society of America as among the currently more challenging strains in clinical management. Assay methods included the standard disc diffusion method and the broth microdilution method for the determination of the minimum inhibitory concentration (MIC) and the minimum bactericidal concentrations (MBC) of the extracts for the test microorganisms. This study revealed the bactericidal activities of all the P. betle leaf crude extracts on methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), extended spectrum β-lactamase-producing Enterobacteriaceae, carbapenem-resistant Enterobacteriaceae, and metallo-β-lactamase-producing Pseudomonas aeruginosa and Acinetobacter baumannii, with minimum bactericidal concentrations that ranged from 19μg/ml to 1250 μg/ml. The extracts proved to be more potent against the Gram positive MRSA and VRE than for the Gram negative test bacteria. VRE isolates were more susceptible to all the extracts than the MRSA isolates. Generally, the ethanol extracts proved to be more potent than the methanol extracts and supercritical CO2 extracts as shown by their lower MICs for both the Gram positive and Gram negative MDRs. MTT cytotoxicity assay showed that the highest concentration (100 μg/ml) of P. betle ethanol extract tested was not toxic to normal human dermal fibroblasts (HDFn). Data from the study firmly established P. betle as an alternative source of anti-infectives against multiple drug resistant bacteria.

  8. Antimicrobial Activities of Methanol, Ethanol and Supercritical CO2 Extracts of Philippine Piper betle L. on Clinical Isolates of Gram Positive and Gram Negative Bacteria with Transferable Multiple Drug Resistance

    PubMed Central

    Valle, Demetrio L.; Cabrera, Esperanza C.; Puzon, Juliana Janet M.; Rivera, Windell L.

    2016-01-01

    Piper betle L. has traditionally been used in alternative medicine in different countries for various therapeutic purposes, including as an anti-infective agent. However, studies reported in the literature are mainly on its activities on drug susceptible bacterial strains. This study determined the antimicrobial activities of its ethanol, methanol, and supercritical CO2 extracts on clinical isolates of multiple drug resistant bacteria which have been identified by the Infectious Disease Society of America as among the currently more challenging strains in clinical management. Assay methods included the standard disc diffusion method and the broth microdilution method for the determination of the minimum inhibitory concentration (MIC) and the minimum bactericidal concentrations (MBC) of the extracts for the test microorganisms. This study revealed the bactericidal activities of all the P. betle leaf crude extracts on methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), extended spectrum β-lactamase-producing Enterobacteriaceae, carbapenem-resistant Enterobacteriaceae, and metallo-β-lactamase-producing Pseudomonas aeruginosa and Acinetobacter baumannii, with minimum bactericidal concentrations that ranged from 19μg/ml to 1250 μg/ml. The extracts proved to be more potent against the Gram positive MRSA and VRE than for the Gram negative test bacteria. VRE isolates were more susceptible to all the extracts than the MRSA isolates. Generally, the ethanol extracts proved to be more potent than the methanol extracts and supercritical CO2 extracts as shown by their lower MICs for both the Gram positive and Gram negative MDRs. MTT cytotoxicity assay showed that the highest concentration (100 μg/ml) of P. betle ethanol extract tested was not toxic to normal human dermal fibroblasts (HDFn). Data from the study firmly established P. betle as an alternative source of anti-infectives against multiple drug resistant bacteria. PMID

  9. Temporal variability of the anthropogenic CO2 storage in the Irminger Sea

    NASA Astrophysics Data System (ADS)

    Pérez, F. F.; Vázquez-Rodríguez, M.; Louarn, E.; Padín, X. A.; Mercier, H.; Ríos, A. F.

    2008-12-01

    The anthropogenic CO2 (Cant) estimates from cruises spanning more than two decades (1981-2006) in the Irminger Sea area of the North Atlantic Subpolar Gyre reveal a large variability in the Cant storage rates. During the early 1990's, the Cant storage rates (2.3±0.6 mol C m-2 yr-1) doubled the average rate for 1981-2006 (1.1±0.1 mol C m-2 yr-1), whilst a remarkable drop to almost half that average followed from 1997 onwards. The Cant storage evolution runs parallel to chlorofluorocarbon-12 inventories and is in good agreement with Cant uptake rates of increase calculated from sea surface pCO2 measurements. The contribution of the Labrador Seawater to the total inventory of Cant in the Irminger basin dropped from 66% in the early 1990s to 49% in the early 2000s. The North Atlantic Oscillation shift from a positive to a negative phase in 1996 led to a reduction of air-sea heat loss in the Labrador Sea. The consequent convection weakening accompanied by an increase in stratification has lowered the efficiency of the northern North Atlantic CO2 sink.

  10. Structurally simple complexes of CO2.

    PubMed

    Murphy, Luke J; Robertson, Katherine N; Kemp, Richard A; Tuononen, Heikki M; Clyburne, Jason A C

    2015-03-07

    The ability to bind CO2 through the formation of low-energy, easily-broken, bonds could prove invaluable in a variety of chemical contexts. For example, weak bonds to CO2 would greatly decrease the cost of the energy-intensive sorbent-regeneration step common to most carbon capture technologies. Furthermore, exploration of this field could lead to the discovery of novel CO2 chemistry. Reduction of complexed carbon dioxide might generate chemical feedstocks for the preparation of value-added products, particularly transportation fuels or fuel precursors. Implementation on a large scale could help to drastically reduce CO2 concentrations in the atmosphere. However, literature examples of weakly bonded complexes of CO2 are relatively few and true coordination complexes to a 'naked' CO2 fragment are nearly unheard of. In this review article, a variety of complexes of CO2 featuring diverse binding modes and reactivity will be examined. Topics covered include: (A) inclusion complexes of CO2 in porous materials. (B) Zwitterionic carbamates produced from the reaction of CO2 with polyamines. (C) Carbamate salts produced from reaction of CO2 with two equivalents of an amine. (D) Insertion products of CO2 into acid-base adducts (e.g., metal complexes). (E) Lewis acid-base activated CO2, such as frustrated Lewis pair complexes. (F) Simple base-CO2 adducts, wherein the base-CO2 bond is the only interaction formed. Complexes in the last category are of particular interest, and include imidazol-2-carboxylates (N-heterocyclic carbene adducts of CO2) as well as a few other examples that lie outside NHC chemistry.

  11. Forest succession at elevated CO2

    SciTech Connect

    Clark, James S.; Schlesinger, William H.

    2002-02-01

    We tested hypotheses concerning the response of forest succession to elevated CO2 in the FACTS-1 site at the Duke Forest. We quantified growth and survival of naturally recruited seedlings, tree saplings, vines, and shrubs under ambient and elevated CO2. We planted seeds and seedlings to augment sample sites. We augmented CO2 treatments with estimates of shade tolerance and nutrient limitation while controlling for soil and light effects to place CO2 treatments within the context of natural variability at the site. Results are now being analyzed and used to parameterize forest models of CO2 response.

  12. Isotopic CO2 Instrumentation for UAV Measurements

    NASA Astrophysics Data System (ADS)

    Gomez, A.; Silver, J.

    2013-12-01

    Carbon dioxide is the largest component of anthroprogenic green house gas emissions. Knowing atmospheric 13CO2/12CO2 ratios precisely is important for understanding biogenic and anthroprogenic sources and sinks for carbon. Instrumentation mounted on UAV aircraft would enable important spatial isotopic CO2 information. However, current isotopic CO2 instrumentation have unfavorable attributes for UAV use, such as high power requirements, high cost, high weight, and large size. Here we present the early development of a compact isotopic CO2 instrument that is designed to nullify effects of pressure, temperature and moisture, and will ultimately be suitable for UAV deployment.

  13. Aminosilicone solvents for CO(2) capture.

    PubMed

    Perry, Robert J; Grocela-Rocha, Teresa A; O'Brien, Michael J; Genovese, Sarah; Wood, Benjamin R; Lewis, Larry N; Lam, Hubert; Soloveichik, Grigorii; Rubinsztajn, Malgorzata; Kniajanski, Sergei; Draper, Sam; Enick, Robert M; Johnson, J Karl; Xie, Hong-bin; Tapriyal, Deepak

    2010-08-23

    This work describes the first report of the use of an aminosilicone solvent mix for the capture of CO(2). To maintain a liquid state, a hydroxyether co-solvent was employed which allowed enhanced physisorption of CO(2) in the solvent mixture. Regeneration of the capture solvent system was demonstrated over 6 cycles and absorption isotherms indicate a 25-50 % increase in dynamic CO(2) capacity over 30 % MEA. In addition, proof of concept for continuous CO(2) absorption was verified. Additionally, modeling to predict heats of reaction of aminosilicone solvents with CO(2) was in good agreement with experimental results.

  14. Air-sea interactions during tropical cyclone in the Indian Ocean

    NASA Astrophysics Data System (ADS)

    Rashmi, R.; Vethamony, P.; Aboobacker, V. M.

    2012-04-01

    Estimation of air-sea momentum flux during tropical cyclone is one of the most important fields of study in wind - wave modeling and prediction. A number of studies suggested that the Charnock coefficient depends on the sea state. The Charnock coefficient (α) is firstly considered as a constant 0.0144 (Charnock, 1955). Toba et al. (1990) suggested that α increases with the wave age (β) based on the observations of mostly young waves in a wave flume, while Donelan (1990), Johnson et al. (1998), Lange et al. (2004), showed that α decreases with the wave age β. Moon et al. (2004) studied the effect of surface waves on Charnock coefficient under tropical cyclones and pointed out that the Charnock coefficient is mainly determined by two parameters: the wave age and the wind speed. Also there is a strong correlation between drag coefficient (Cd) and wave age (β) for each wind speed. When the wind speed is higher than 30 m/s, Cd will increase with β, otherwise Cd will decrease with increasing β. Amorocho et al. (1980) showed that three regions exist in the development of the wind stress: (i) a lower region in which the wind waves have not begun to break, for which drag coefficient (Cd) is approximately constant; (ii) a transitional region after the onset of breakers, for which Cd varies non-linearly with U10; (iii) a limiting region for which Cd tends again toward a constant value, and corresponds to a condition of breaker saturation. The three regions described above can be classified as 'low roughness', 'transitional', and 'high roughness', respectively. Wavewatch III model was used to study the air sea interaction during tropical cyclone in the Indian Ocean. ECMWF winds (2.5° x 2.5°) have been used for forcing the wave model. Air-sea momentum data was obtained by simulating wave fields of tropical cyclones during 1996 in the Indian Ocean. The wave parameters from the model results have been compared with measured buoy data and with merged altimeter data. The

  15. A numerical coupled model for studying air-sea-wave interaction

    NASA Astrophysics Data System (ADS)

    Ly, Le Ngoc

    1995-10-01

    A numerical coupled model of air-sea-wave interaction is developed to study the influence of ocean wind waves on dynamical, turbulent structures of the air-sea system and their impact on coupled modeling. The model equations for both atmospheric and oceanic boundary layers include equations for: (1) momentum, (2) a k-ɛ turbulence scheme, and (3) stratification in the atmospheric and oceanic boundary layers. The model equations are written in the same form for both the atmosphere and ocean. In this model, wind waves are considered as another source of turbulent energy in the upper layer of the ocean besides turbulent energy from shear production. The dissipation ɛ at the ocean surface is written as a linear combination of terms representing dissipation from mean flow and breaking waves. The ɛ from breaking waves is estimated by using similarity theory and observed data. It is written in terms of wave parameters such as wave phase speed, height, and length, which are then expressed in terms of friction velocity. Numerical experiments are designed for various geostrophic winds, wave heights, and wave ages, to study the influence of waves on the air-sea system. The numerical simulations show that the vertical profiles of ɛ in the atmospheric and oceanic boundary layers (AOBL) are similar. The magnitudes of ɛ in the oceanic surface zone are much larger than those in the atmospheric surface zone and in the interior of the oceanic boundary layer (OBL). The model predicts ɛ distributions with a surface zone of large dissipation which was not expected from similarity scaling based on observed wind stress and surface buoyancy. The simulations also show that waves have a strong influence on eddy viscosity coefficients (EVC) and momentum fluxes, and have a dominated effect on the component of fluxes in the direction of the wind. The depth of large changes in flux magnitudes and EVC in the ocean can reach to 10-20 m. The simulations of surface drift currents confirm that

  16. Measurements of mixing layer height variability during the Ligurian air-sea interaction experiment (LASIE '07)

    NASA Astrophysics Data System (ADS)

    Förster, J.

    2009-09-01

    Air-sea interaction processes play a dominant role with respect to detection ranges of shipborne radar and infrared sensor systems. Especially in the littoral most often temperature and humidity gradients affect propagation paths and are the reason for abnormal phenomena such as ducting or mirage. Besides refractivity, spray and aerosols ejected from the sea surface can further degrade the quality of shipborne surveillance systems. Thus environmental effects might seriously hamper ship self defense. During the Ligurian Air-Sea Interaction Experiment (LASIE '07 - 16.06.-26.06.2007) the Federal Armed Forces Underwater Acoustics and Marine Geophysics Research Institute (FWG) carried out simultaneous in-situ measurements of meteorological and oceanographic parameters to study air-sea interaction processes with respect to littoral boundary layer variability. The characterization of the environment included both, in-situ measurements of atmospheric and sea surface parameters. Investigations were carried out on board RV PLANET, RV URANIA and at the ODAS-Italy1 buoy of the Italian National Council of Research (CNR). On board RV PLANET the sea surface and meteorological conditions were analyzed by two multi-sensor buoys, ship sensors and radiosondes. Emphasis was given to the vertical structure of the Marine Boundary Layer (MBL) and its variability. It was analyzed by a one lense lidar ceilometer CL31, a tethersonde system TT12 and radiosondes RS92 (Vaisala). The latter were launched every three hours. The TT12 consisted of three radiosondes, which could be adapted to separate altitudes of special interest. The experiment was characterized by changing meteorological conditions resulting in offshore and onshore blowing winds. In the first case the air temperature TAir was higher than the sea surface temperature TWater leading to a very stable surface layer. This situation was associated with a strong temperature inversion and a very clear atmosphere with a visibility of

  17. Air-sea exchange over Black Sea estimated from high resolution regional climate simulations

    NASA Astrophysics Data System (ADS)

    Velea, Liliana; Bojariu, Roxana; Cica, Roxana

    2013-04-01

    Black Sea is an important influencing factor for the climate of bordering countries, showing cyclogenetic activity (Trigo et al, 1999) and influencing Mediterranean cyclones passing over. As for other seas, standard observations of the atmosphere are limited in time and space and available observation-based estimations of air-sea exchange terms present quite large ranges of uncertainty. The reanalysis datasets (e.g. ERA produced by ECMWF) provide promising validation estimates of climatic characteristics against the ones in available climatic data (Schrum et al, 2001), while cannot reproduce some local features due to relatively coarse horizontal resolution. Detailed and realistic information on smaller-scale processes are foreseen to be provided by regional climate models, due to continuous improvements of physical parameterizations and numerical solutions and thus affording simulations at high spatial resolution. The aim of the study is to assess the potential of three regional climate models in reproducing known climatological characteristics of air-sea exchange over Black Sea, as well as to explore the added value of the model compared to the input (reanalysis) data. We employ results of long-term (1961-2000) simulations performed within ENSEMBLE project (http://ensemblesrt3.dmi.dk/) using models ETHZ-CLM, CNRM-ALADIN, METO-HadCM, for which the integration domain covers the whole area of interest. The analysis is performed for the entire basin for several variables entering the heat and water budget terms and available as direct output from the models, at seasonal and annual scale. A comparison with independent data (ERA-INTERIM) and findings from other studies (e.g. Schrum et al, 2001) is also presented. References: Schrum, C., Staneva, J., Stanev, E. and Ozsoy, E., 2001: Air-sea exchange in the Black Sea estimated from atmospheric analysis for the period 1979-1993, J. Marine Systems, 31, 3-19 Trigo, I. F., T. D. Davies, and G. R. Bigg (1999): Objective

  18. Selecting CO2 Sources for CO2 Utilization by Environmental-Merit-Order Curves.

    PubMed

    von der Assen, Niklas; Müller, Leonard J; Steingrube, Annette; Voll, Philip; Bardow, André

    2016-02-02

    Capture and utilization of CO2 as alternative carbon feedstock for fuels, chemicals, and materials aims at reducing greenhouse gas emissions and fossil resource use. For capture of CO2, a large variety of CO2 sources exists. Since they emit much more CO2 than the expected demand for CO2 utilization, the environmentally most favorable CO2 sources should be selected. For this purpose, we introduce the environmental-merit-order (EMO) curve to rank CO2 sources according to their environmental impacts over the available CO2 supply. To determine the environmental impacts of CO2 capture, compression and transport, we conducted a comprehensive literature study for the energy demands of CO2 supply, and constructed a database for CO2 sources in Europe. Mapping these CO2 sources reveals that CO2 transport distances are usually small. Thus, neglecting transport in a first step, we find that environmental impacts are minimized by capturing CO2 first from chemical plants and natural gas processing, then from paper mills, power plants, and iron and steel plants. In a second step, we computed regional EMO curves considering transport and country-specific impacts for energy supply. Building upon regional EMO curves, we identify favorable locations for CO2 utilization with lowest environmental impacts of CO2 supply, so-called CO2 oases.

  19. Microbial Growth under Supercritical CO2

    PubMed Central

    Peet, Kyle C.; Freedman, Adam J. E.; Hernandez, Hector H.; Britto, Vanya; Boreham, Chris; Ajo-Franklin, Jonathan B.

    2015-01-01

    Growth of microorganisms in environments containing CO2 above its critical point is unexpected due to a combination of deleterious effects, including cytoplasmic acidification and membrane destabilization. Thus, supercritical CO2 (scCO2) is generally regarded as a sterilizing agent. We report isolation of bacteria from three sites targeted for geologic carbon dioxide sequestration (GCS) that are capable of growth in pressurized bioreactors containing scCO2. Analysis of 16S rRNA genes from scCO2 enrichment cultures revealed microbial assemblages of varied complexity, including representatives of the genus Bacillus. Propagation of enrichment cultures under scCO2 headspace led to isolation of six strains corresponding to Bacillus cereus, Bacillus subterraneus, Bacillus amyloliquefaciens, Bacillus safensis, and Bacillus megaterium. Isolates are spore-forming, facultative anaerobes and capable of germination and growth under an scCO2 headspace. In addition to these isolates, several Bacillus type strains grew under scCO2, suggesting that this may be a shared feature of spore-forming Bacillus spp. Our results provide direct evidence of microbial activity at the interface between scCO2 and an aqueous phase. Since microbial activity can influence the key mechanisms for permanent storage of sequestered CO2 (i.e., structural, residual, solubility, and mineral trapping), our work suggests that during GCS microorganisms may grow and catalyze biological reactions that influence the fate and transport of CO2 in the deep subsurface. PMID:25681188

  20. Microbial growth under supercritical CO2.

    PubMed

    Peet, Kyle C; Freedman, Adam J E; Hernandez, Hector H; Britto, Vanya; Boreham, Chris; Ajo-Franklin, Jonathan B; Thompson, Janelle R

    2015-04-01

    Growth of microorganisms in environments containing CO2 above its critical point is unexpected due to a combination of deleterious effects, including cytoplasmic acidification and membrane destabilization. Thus, supercritical CO2 (scCO2) is generally regarded as a sterilizing agent. We report isolation of bacteria from three sites targeted for geologic carbon dioxide sequestration (GCS) that are capable of growth in pressurized bioreactors containing scCO2. Analysis of 16S rRNA genes from scCO2 enrichment cultures revealed microbial assemblages of varied complexity, including representatives of the genus Bacillus. Propagation of enrichment cultures under scCO2 headspace led to isolation of six strains corresponding to Bacillus cereus, Bacillus subterraneus, Bacillus amyloliquefaciens, Bacillus safensis, and Bacillus megaterium. Isolates are spore-forming, facultative anaerobes and capable of germination and growth under an scCO2 headspace. In addition to these isolates, several Bacillus type strains grew under scCO2, suggesting that this may be a shared feature of spore-forming Bacillus spp. Our results provide direct evidence of microbial activity at the interface between scCO2 and an aqueous phase. Since microbial activity can influence the key mechanisms for permanent storage of sequestered CO2 (i.e., structural, residual, solubility, and mineral trapping), our work suggests that during GCS microorganisms may grow and catalyze biological reactions that influence the fate and transport of CO2 in the deep subsurface.

  1. Amine scrubbing for CO2 capture.

    PubMed

    Rochelle, Gary T

    2009-09-25

    Amine scrubbing has been used to separate carbon dioxide (CO2) from natural gas and hydrogen since 1930. It is a robust technology and is ready to be tested and used on a larger scale for CO2 capture from coal-fired power plants. The minimum work requirement to separate CO2 from coal-fired flue gas and compress CO2 to 150 bar is 0.11 megawatt-hours per metric ton of CO2. Process and solvent improvements should reduce the energy consumption to 0.2 megawatt-hour per ton of CO2. Other advanced technologies will not provide energy-efficient or timely solutions to CO2 emission from conventional coal-fired power plants.

  2. The future of the carbon cycle: review, calcification response, ballast and feedback on atmospheric CO2.

    PubMed

    Barker, S; Higgins, J A; Elderfield, H

    2003-09-15

    The operation of the carbon cycle forms an important part of the processes relevant to future changes in atmospheric carbon dioxide. The balance of carbon between terrestrial and oceanic reservoirs is an important factor and here we focus in particular on the oceans. Future changes in the carbon cycle that may affect air-sea partitioning of CO(2) are difficult to quantify but the palaeoceanographic record and modern observational studies provide important evidence of what variations might occur. These include changes in surface nutrient use, the oceanic inventory of nutrients, and the elemental composition and rain-rate ratio of marine particles. Recent work has identified two inter-linked processes of potential importance that we consider in some detail: the response of marine calcification to changes in surface water CO(2) and the association of particulate organic carbon with ballast minerals, in particular biogenic calcite. We review evidence from corals, coccolithophores and foraminifera, which suggests that the response of reduced calcification provides a negative feedback on rising atmospheric CO(2). We then use a box model to demonstrate how the calcification response may affect the organic carbon rain rate through the ballast effect. The ballast effect on export fluxes of organic and inorganic carbon acts to counteract the negative calcification response to increased CO(2). Thus, two oceanic buffers exert a significant control on ocean-atmosphere carbonate chemistry: the thermodynamic CO(2) buffer; and the ballast/calcification buffer. Just how tightly coupled the rain-rate ratio of CaCO(3)/C(org) is to fluxes of ballast minerals is an important question for future research.

  3. Atmospheric CO2 observations and models suggest strong carbon uptake by forests in New Zealand

    NASA Astrophysics Data System (ADS)

    Steinkamp, Kay; Mikaloff Fletcher, Sara E.; Brailsford, Gordon; Smale, Dan; Moore, Stuart; Keller, Elizabeth D.; Baisden, W. Troy; Mukai, Hitoshi; Stephens, Britton B.

    2017-01-01

    A regional atmospheric inversion method has been developed to determine the spatial and temporal distribution of CO2 sinks and sources across New Zealand for 2011-2013. This approach infers net air-sea and air-land CO2 fluxes from measurement records, using back-trajectory simulations from the Numerical Atmospheric dispersion Modelling Environment (NAME) Lagrangian dispersion model, driven by meteorology from the New Zealand Limited Area Model (NZLAM) weather prediction model. The inversion uses in situ measurements from two fixed sites, Baring Head on the southern tip of New Zealand's North Island (41.408° S, 174.871° E) and Lauder from the central South Island (45.038° S, 169.684° E), and ship board data from monthly cruises between Japan, New Zealand, and Australia. A range of scenarios is used to assess the sensitivity of the inversion method to underlying assumptions and to ensure robustness of the results. The results indicate a strong seasonal cycle in terrestrial land fluxes from the South Island of New Zealand, especially in western regions covered by indigenous forest, suggesting higher photosynthetic and respiratory activity than is evident in the current a priori land process model. On the annual scale, the terrestrial biosphere in New Zealand is estimated to be a net CO2 sink, removing 98 (±37) Tg CO2 yr-1 from the atmosphere on average during 2011-2013. This sink is much larger than the reported 27 Tg CO2 yr-1 from the national inventory for the same time period. The difference can be partially reconciled when factors related to forest and agricultural management and exports, fossil fuel emission estimates, hydrologic fluxes, and soil carbon change are considered, but some differences are likely to remain. Baseline uncertainty, model transport uncertainty, and limited sensitivity to the northern half of the North Island are the main contributors to flux uncertainty.

  4. New insights into fCO2 variability in the tropical eastern Pacific Ocean using SMOS SSS

    NASA Astrophysics Data System (ADS)

    Walker Brown, C.; Boutin, J.; Merlivat, L.

    2015-12-01

    Complex oceanic circulation and air-sea interaction make the eastern tropical Pacific Ocean (ETPO) a highly variable source of CO2 to the atmosphere. Although the scientific community have amassed 70 000 surface fugacities of carbon dioxide (fCO2) data points within the ETPO region over the past 25 years, the spatial and temporal resolution of this data set is insufficient to fully quantify the seasonal to interannual variability of the region, a region where fCO2 has been observed to fluctuate by > 300 μatm. Upwelling and rainfall events dominate the surface physical and chemical characteristics of the ETPO, with both yielding unique signatures in sea surface temperature and salinity. Thus, we explore the potential of using a statistical description of fCO2 within sea-surface salinity-temperature space. These SSS/SST relationships are based on in situ surface ocean CO2 atlas (SOCAT) data collected within the ETPO. This statistical description is then applied to high-resolution (0.25°) Soil Moisture and Ocean Salinity (SMOS) sea surface salinity (SSS) and Operational Sea Surface Temperature and Sea Ice Analysis (OSTIA) sea surface temperature (SST) in order to compute regional fCO2. As a result, we are able to resolve fCO2 at sufficiently high resolution to elucidate the influence that various physical processes have on the fCO2 of the surface ETPO. Normalised (to 2014) oceanic fCO2 between July 2010 and June 2014 within the entire ETPO was 39 (±10.7) μatm supersaturated with respect to 2014 atmospheric partial pressures, and featured a CO2 outgassing of 1.51 (±0.41) mmol m-2 d-1. Values of fCO2 within the ETPO were found to be broadly split between the Gulf of Panama region and the rest of the tropical eastern Pacific Ocean. The northwest, central and offshore regions were supersaturated, with wintertime wind-jet-driven upwelling found to constitute the first-order control on fCO2 values. This contrasts with the southeastern/Gulf of Panama region, where heavy

  5. Historical changes in carbon dioxide (CO2) and dimethyl sulphide (DMS) emissions in the eutrophied Southern North Sea

    NASA Astrophysics Data System (ADS)

    Gypens, N.; Borges, A. V.; Lancelot, C.

    2012-04-01

    Anthropogenic activities after the Second World War have severely increased river nutrient [nitrogen (N) and phosphorus (P)] loads to European coastal areas. The resulting N: P: Si imbalance (compared to phytoplankton requirements) stimulated in the Southern North Sea the growth of Phaeocystis colonies modifying the functioning of the ecosystem and, therefore, the carbon but also the biogenic sulphur cycles. Phaeocystis is a significant producer of DMSP (dimethylsulphide propionate), the precursor of DMS. When emitted to the atmosphere the DMS has a cooling effect on the climate contrarily to the CO2 greenhouse gas. Since the late 1990's specific nutrient reduction policies have however considerably reduced P loads while N is maintained. In this application we explore, with a mathematical tool, the effects of changing N and P loads on air-sea CO2 exchanges and DMS marine emissions. The chosen model is the MIRO-CO2-DMS, a complex biogeochemical model describing carbon, biogenic sulphur and nutrient cycles in the marine domain. Model simulations are performed for the contemporary period since 1950, using real forcing fields for sea surface temperature, wind speed and atmospheric CO2 and RIVERSTRAHLER model simulations for river carbon and nutrient loads. Results are discussing the importance of human activities and river inputs of carbon and nutrients on the eutrophication of coastal areas, their ability to absorb atmospheric CO2 and the importance of DMS emissions associated with phytoplankton blooms, especially Phaeocystis.

  6. Fast Discharge Circuit for Longitudinally Excited CO2 Laser

    NASA Astrophysics Data System (ADS)

    Uno, Kazuyuki; Hayashi, Hiroyuki; Akitsu, Tetsuya; Jitsuno, Takahisa

    2013-04-01

    In a longitudinally excited CO2 laser with a short laser pulse, similarly to TEA and Q-switched CO2 lasers, a fast discharge is very important. We investigated the use of a fast discharge circuit to obtain a high spike laser pulse in a longitudinally excited CO2 laser. We compared a traditional capacitor-transfer circuit having a buffer capacitance of 700 pF with our direct-drive circuit in which the buffer capacitance is removed. The direct-drive circuit produced a fast discharge and a high spike laser pulse. We also investigated the effect of a resistance connected in parallel with the discharge tube to eliminate low discharge current after the main discharge. A low resistance of 1 kΩ or less acted as a shunt resistance. The shunt resistance was effective in decreasing the energy of the laser pulse tail at high gas pressure.

  7. Fourier Transform Microwave Spectra of CO{2}-ETHYLENE Sulfide, CO{2}-ETHYLENE Oxide and CO{2}-PROPYLENE Oxide Complexes

    NASA Astrophysics Data System (ADS)

    Orita, Yukari; Kawashima, Yoshiyuki; Hirota, Eizi

    2010-06-01

    We have previously examined the difference in roles of O and S in structure and dynamics of the CO-ethylene oxide (EO) and CO-ethylene sulfide (ES) complexes. We have extended the investigation to CO{2}-EO and CO{2}-ES for comparison. We have also observed the CO{2}-propylene oxide (PO) complex, which is an important intermediate in the reaction of PO with CO{2} leading to polycarbonate. Both a-type and b-type transitions were observed for the CO{2}-EO and CO{2}-ES, but no c-type transitions were observed at all. We also detected the {34}S and {13}C isotopic species in natural abundance and the species containing {18}OCO and C{18}O% {2}, which were synthesized by burning paper in an {18}O{2} and{% 16}O{2} mixture. By analyzing the observed spectra we concluded the CO{2} moiety of CO{2}-EO and CO{2}-ES located in a plane % prependicular to the three-membered ring and bisecting the COC or CSC angle of EO or ES, respectively, as in the case of CO-EO and CO-ES complexes. An % ab initio MO calculation at the level of MP2/6-311G(d, p) yielded an optimized structure in good agreement with the experimental result. We have derived from the observed spectra the distance, the stretching force constant, and the binding energy of the bonds between the constituents of the CO{2}-EO and CO{2}-ES complexes and have found that the distances of the two complexes were shorter by 0.2Å than those in CO-EO and CO-ES, respectively, and that the intermolecular bonds were two times stronger in the CO{2} complexes than in the corresponding CO complexes. We have concluded from the observed spectra that the CO{2} moiety in CO{2}-PO is located on the PO three-membered ring plane opposite to the methyl group. The constituents in CO{2}-PO were more weakly bound than those in CO{2}-EO and CO{2}-ES. S. Sato, Y. Kawashima, Y. Tatamitani, and E. Hirota, 63rd International Symposium on Molecular Spectroscopy, WF05 (2008).

  8. Molecular dynamics simulation of the key characteristics of the supercritical CO2-pentaerythritol tetraacetate system

    NASA Astrophysics Data System (ADS)

    Lei, Peiyu; Jin, Zunlong; Liu, Hong; Wang, Dingbiao; Liu, Donglai

    2016-12-01

    Supercritical CO2 is widely used in many fields of industry. Investigation of statistical mechanics of CO2 fluid under quasi critical and supercritical state has great significance. Equilibrium molecular dynamics (EMD) simulations are carried out to investigate the statistical mechanics and macroscopic performance of CO2 fluid under the quasi critical and supercritical state. The results show that the bond length and bond angle distributions for supercritical CO2 are Gaussian distribution basically. The dimers' proportion of supercritical CO2 system changes with pressure increasing. T-type dimer has high share within the system when pressure is higher than 9MPa. It can be inferred that T-type dimer leads to CO2 physical properties changing tempestuously under supercritical state. The effect that lubricating oil has on microstructure and heat transfer of supercritical CO2 is also investigated in the present work. The results show the lubricating oil produces significant effect on the dimers' structure under low pressure.

  9. The EOSDIS Version 0 Distributed Active Archive Center for physical oceanography and air-sea interaction

    NASA Technical Reports Server (NTRS)

    Hilland, Jeffrey E.; Collins, Donald J.; Nichols, David A.

    1991-01-01

    The Distributed Active Archive Center (DAAC) at the Jet Propulsion Laboratory will support scientists specializing in physical oceanography and air-sea interaction. As part of the NASA Earth Observing System Data and Information System Version 0 the DAAC will build on existing capabilities to provide services for data product generation, archiving, distribution and management of information about data. To meet scientist's immediate needs for data, existing data sets from missions such as Seasat, Geosat, the NOAA series of satellites and the Global Positioning Satellite system will be distributed to investigators upon request. In 1992, ocean topography, wave and surface roughness data from the Topex/Poseidon radar altimeter mission will be archived and distributed. New data products will be derived from Topex/Poseidon and other sensor systems based on recommendations of the science community. In 1995, ocean wind field measurements from the NASA Scatterometer will be supported by the DAAC.

  10. An air/sea flux model including the effects of capillary waves

    NASA Technical Reports Server (NTRS)

    Bourassa, Mark A.

    1993-01-01

    An improved model of the air/sea interface is developed. The improvements consist in including the effect of capillary (surface tension) waves on the tropical surface fluxes and the consideration of the sea state, both of which increase the magnitude of tropical surface fluxes. Changes in surface stress are most significant in the low wind-speed regions, which include the areas where westerly bursts occur. It is shown that the changes, from the regular wind conditions to those of a westerly burst or El-Nino, can double when the effects of capillary waves are considered. This implies a much stronger coupling between the ocean and the atmosphere than is predicted by other boundary layer models.

  11. Air-sea fluxes and surface layer turbulence around a sea surface temperature front

    NASA Technical Reports Server (NTRS)

    Friehe, C. A.; Shaw, W. J.; Davidson, K. L.; Rogers, D. P.; Large, W. G.; Stage, S. A.; Crescenti, G. H.; Khalsa, S. J. S.; Greenhut, G. K.; Li, F.

    1991-01-01

    The observed effects of sharp changes in sea surface temperature (SST) on the air-sea fluxes, surface roughness, and the turbulence structure in the surface layer and the marine atmospheric boundary layer are discussed. In situ flux and turbulence observations were carried out from three aircraft and two ships within the FASINEX framework. Three other aircraft used remote sensors to measure waves, microwave backscatter, and lidar signatures of cloud tops. Descriptions of the techniques, intercomparison of aircraft and ship flux data, and use of different methods for analyzing the fluxes from the aircraft data are described. Changing synoptic weather on three successive days yielded cases of wind direction both approximately parallel and perpendicular to a surface temperature front. For the wind perpendicular to the front, wind over both cold-to-warm and warm-to-cold surface temperatures occurred. Model results consistent with the observations suggest that an internal boundary layer forms at the SST.

  12. South Atlantic sea surface temperature anomalies and air-sea interactions: stochastic models

    NASA Astrophysics Data System (ADS)

    Dobrovolski, S. G.

    1994-09-01

    Data on the South Atlantic monthly sea surface temperature anomalies (SSTA) are analysed using the maximum-entropy method. It is shown that the Markov first-order process can describe, to a first approximation, SSTA series. The region of maximum SSTA values coincides with the zone of maximum residual white noise values (sub-Antarctic hydrological front). The theory of dynamic-stochastic climate models is applied to estimate the variability of South Atlantic SSTA and air-sea interactions. The Adem model is used as a deterministic block of the dynamic-stochastic model. Experiments show satisfactorily the SSTA intensification in the sub-Antarctic front zone, with appropriate standard deviations, and demonstrate the leading role of the abnormal drift currents in these processes.

  13. A climatology of air-sea interactions at the Mediterranean LION and AZUR buoys

    NASA Astrophysics Data System (ADS)

    Caniaux, Guy; Prieur, Louis; Bouin, Marie-Noëlle; Giordani, Hervé

    2014-05-01

    The LION and AZUR buoys (respectively at 42.1°N 4.7°E and 43.4°N 7.8°E) provide an extended data set since respectively 1999 and 2001 to present for studying air-sea interactions in the northwestern Mediterranean basin. The two buoys are located where high wind events occur (resp. north western and north easterly gale winds), that force and condition deep oceanic winter convection in that region. A short-term climatology (resp. 13 and 11 years) of air-sea interactions has been developed, which includes classical meteo-oceanic parameters, but also waves period and significant wave heights and radiative fluxes. Moreover turbulent surface fluxes have been estimated from various bulk parameterizations, in order to estimate uncertainties on fluxes. An important dispersion of turbulent fluxes is found at high wind speeds according to the parameterization used, larger than taking into account the second order effects of cool skin, warm layer and waves. An important annual cycle affects air temperatures (ATs), SSTs and turbulent fluxes at the two buoys. The annual cycle of ATs and SSTs can be well reconstructed from the first two annual harmonics, while for the turbulent heat fluxes the erratic occurrence of high and low flux events, well correlated with high/dry and low windy periods, strongly affect their annual and interannual cycles. The frequency of high surface heat fluxes and high wind stress is found highest during the autumn and winter months, despite the fact that north-westerly gale winds occur all year long at LION buoy. During calm weather period, ATs and SSTs experience an important diurnal cycle (on average 1 and 0.5°C respectively), that affect latent and sensible heat fluxes. Finally, an estimate of the interannual variability of the turbulent fluxes in Autumn and Winter is discussed, in order to characterize their potential role on deep ocean convection.

  14. Gulf of Mexico Air/Sea Interaction: Measurements and Initial Data Characterization

    NASA Astrophysics Data System (ADS)

    MacDonald, C.; Huang, C. H.; Roberts, P. T.; Bariteau, L.; Fairall, C. W.; Gibson, W.; Ray, A.

    2011-12-01

    Corporate, government, and university researchers collaborated to develop an atmospheric boundary layer environmental observations program on an offshore platform in the Gulf of Mexico. The primary goals of this project were to provide data to (1) improve our understanding of boundary layer processes and air-sea interaction over the Gulf of Mexico; (2) improve regional-scale meteorological and air quality modeling; and (3) provide a framework for advanced offshore measurements to support future needs such as emergency response, exploration and lease decisions, wind energy research and development, and meteorological and air quality forecasting. In October 2010, meteorological and oceanographic sensors were deployed for an extended period (approximately 12 months) on a Chevron service platform (ST 52B, 90.5W, 29N) to collect boundary layer and sea surface data sufficient to support these objectives. This project has significant importance given the large industrial presence in the Gulf, sizeable regional population nearby, and the recognized need for precise and timely pollutant forecasts. Observations from this project include surface meteorology; sodar marine boundary layer winds; microwave radiometer profiles of temperature, relative humidity, and liquid water; ceilometer cloud base heights; water temperature and current profiles; sea surface temperature; wave height statistics; downwelling solar and infrared radiation; and air-sea turbulent momentum and heat fluxes. This project resulted in the collection of an unprecedented set of boundary layer measurements over the Gulf of Mexico that capture the range of meteorological and oceanographic interactions and processes that occur over an entire year. This presentation will provide insight into the logistical and scientific issues associated with the deployment and operations of unique measurements in offshore areas and provide results from an initial data analysis of boundary layer processes over the Gulf of

  15. Assessing Air-Sea Interaction in the Evolving NASA GEOS Model

    NASA Technical Reports Server (NTRS)

    Clayson, Carol Anne; Roberts, J. Brent

    2015-01-01

    In order to understand how the climate responds to variations in forcing, one necessary component is to understand the full distribution of variability of exchanges of heat and moisture between the atmosphere and ocean. Surface heat and moisture fluxes are critical to the generation and decay of many coupled air-sea phenomena. These mechanisms operate across a number of scales and contain contributions from interactions between the anomalous (i.e. non-mean), often extreme-valued, flux components. Satellite-derived estimates of the surface turbulent and radiative heat fluxes provide an opportunity to assess results from modeling systems. Evaluation of only time mean and variability statistics, however only provides limited traceability to processes controlling what are often regime-dependent errors. This work will present an approach to evaluate the representation of the turbulent fluxes at the air-sea interface in the current and evolving Goddard Earth Observing System (GEOS) model. A temperature and moisture vertical profile-based clustering technique is used to identify robust weather regimes, and subsequently intercompare the turbulent fluxes and near-surface parameters within these regimes in both satellite estimates and GEOS-driven data sets. Both model reanalysis (MERRA) and seasonal-to-interannual coupled GEOS model simulations will be evaluated. Particular emphasis is placed on understanding the distribution of the fluxes including extremes, and the representation of near-surface forcing variables directly related to their estimation. Results from these analyses will help identify the existence and source of regime-dependent biases in the GEOS model ocean surface turbulent fluxes. The use of the temperature and moisture profiles for weather-state clustering will be highlighted for its potential broad application to 3-D output typical of model simulations.

  16. Indirect air-sea interactions simulated with a coupled turbulence-resolving model

    NASA Astrophysics Data System (ADS)

    Esau, Igor

    2014-05-01

    A turbulence-resolving parallelized atmospheric large-eddy simulation model (PALM) has been applied to study turbulent interactions between the humid atmospheric boundary layer (ABL) and the salt water oceanic mixed layer (OML). The most energetic three-dimensional turbulent eddies in the ABL-OML system (convective cells) were explicitly resolved in these simulations. This study considers a case of shear-free convection in the coupled ABL-OML system. The ABL-OML coupling scheme used the turbulent fluxes at the bottom of the ABL as upper boundary conditions for the OML and the sea surface temperature at the top of the OML as lower boundary conditions for the ABL. The analysis of the numerical experiment confirms that the ABL-OML interactions involve both the traditional direct coupling mechanism and much less studied indirect coupling mechanism (Garrett Dyn Atmos Ocean 23:19-34, 1996). The direct coupling refers to a common flux-gradient representation of the air-sea exchange, which is controlled by the temperature difference across the air-water interface. The indirect coupling refers to thermal instability of the Rayleigh-Benard convection, which is controlled by the temperature difference across the entire mixed layer through formation of the large convective eddies or cells. The indirect coupling mechanism in these simulations explained up to 45 % of the ABL-OML co-variability on the turbulent scales. Despite relatively small amplitude of the sea surface temperature fluctuations, persistence of the OML cells organizes the ABL convective cells. Water downdrafts in the OML cells tend to be collocated with air updrafts in the ABL cells. The study concludes that the convective structures in the ABL and the OML are co-organized. The OML convection controls the air-sea turbulent exchange in the quasi-equilibrium convective ABL-OML system.

  17. Towards More Realistic Simulation of Air-Sea Interaction over Lakes on Titan

    NASA Astrophysics Data System (ADS)

    Rafkin, Scot; Soto, Alejandro

    2016-06-01

    The exchange of methane between the atmosphere and surface liquid reservoirs dominates the short time-scale methanological cycle. In this study, previous two-dimensional simulations of the exchange of methane vapor, sensible heat and momentum between the atmosphere and lakes are updated with the inclusion of radiative forcing and extended to three dimensions, including the introduction of realistic coastlines. Previous studies of Titan's air-sea exchange in two dimensions suggested that the exchange process was self-limiting. Evaporation from lakes produced a shallow but extremely stable marine layer that suppressed turbulent exchange. Furthermore, the circulation associated with the higher buoyancy of methane-rich atmosphere over the lake was offset by the oppositely directed thermal sea breeze circulation, which muted the mean wind. Two major weaknesses of this previous work were the lack of radiative forcing and the imposition of two dimensionality that limited the full range of dynamical solutions. Based on early theoretical studies, it was thought that magnitude of turbulent energy flux exchanges would be much larger than radiative fluxes, thereby justifying the neglect of radiation, but the two-dimensional simulations indicated that this was not a valid assumption. The dynamical limitations of two-dimensional simulations are well known. Vorticity stretching (i.e., circulation intensification through vertical motion) is not possible and it is also not possible to produce dynamically balanced gradient wind-type circulations. As well, the irregular shape of a realistic coastline cannot be expressed in two dimensions, and these realistic structures will generally induce complex convergence and divergence circulations in the atmosphere. The impact of radiative forcing and the addition of the third dimension on the air-sea exchange are presented.

  18. Unravelling air-sea interactions driven by photochemistry in the sea-surface microlayer

    NASA Astrophysics Data System (ADS)

    George, Christian; Alpert, Peter; Tinel, Liselotte; Rossignol, Stéphanie; Perrier, Sébastien; Bernard, Francois; Ciuraru, Raluca; Hayeck, Nathalie

    2016-04-01

    Interfaces are ubiquitous in the environment, and in addition many atmospheric key processes, such as gas deposition, aerosol and cloud formation are, at one stage or the other, strongly impacted by physical- and chemical processes occurring at interfaces. Unfortunately, these processes have only been suggested and discussed but never fully addressed because they were beyond reach. We suggest now that photochemistry or photosensitized reactions exist at interfaces, and we will present and discuss their possible atmospheric implications. Obviously, one of the largest interface is the sea-surface microlayer (SML), which is a region lying at the uppermost tens to hundreds of micrometres of the water surface, with physical, chemical and biological properties that differ from those of the underlying sub-surface water. Organic film formation at the sea surface is made possible in the presence of an excess of surface-active material. Hydrophobic surfactant films are typically believed to play the role of a physical barrier to air-sea exchanges, especially at low wind speed. We will show that dissolved organic matter (DOM) can trigger photochemistry at the air-sea interface, releasing unsaturated, functionalized volatile organic compounds (VOCs), including isoprene,... acting as precursors for the formation of organic aerosols, that were thought, up to now, to be solely of biological origin! In addition, we suggest that when arranged at an air/water interface, hydrophobic surfactant can have weak chemical interactions among them, which can trigger the absorption of sunlight and can consequently induce photochemistry at such interfaces. A major question arises from such observations, namely: can the existence of such weak intra- or intermolecular interactions and the subsequent photochemistry be generalized to many other atmospheric objects such as aerosols? This topic will be presented and discussed.

  19. Earth's Atmospheric CO2 Saturated IR Absorption

    NASA Astrophysics Data System (ADS)

    Wall, Ernst

    2008-10-01

    Using the on-line SpectraCalc IR absorption simulator, the amount of IR absorption by the 15 μ line of the current atmospheric CO2 was obtained and compared with that of twice the amount of CO2. The simulation required a fixed density equivalent for the atmospheric path length. This was obtained by numerically integrating the NOAA Standard Atmospheric model. While the current line is saturated, doubling the CO2 will cause a slight width increase. Using this and the blackbody radiation curve plus considering the effects of water vapor, the temperature rise of the Earth will be less than 2.5 deg. C. Integrating a NASA Martian atmospheric model, we find that the Martian atmosphere has 45 times more CO2 to penetrate than Earth, and yet, the Martian diurnal temperature swings exceed those of the Sahara desert. I.e., large amounts of CO2 alone do not necessarily cause planetary warming. As the oceans warm from any cause, more CO2 is boiled out, but if they cool, they will absorb more CO2 just as a carbonated drink does, so that temperature and CO2 density will correlate. It is to be noted that the Earth's known petroleum reserves contain only enough CO2 to increase the atmospheric CO2 by some 15%.

  20. CO2 transport over complex terrain

    USGS Publications Warehouse

    Sun, Jielun; Burns, Sean P.; Delany, A.C.; Oncley, S.P.; Turnipseed, A.A.; Stephens, B.B.; Lenschow, D.H.; LeMone, M.A.; Monson, Russell K.; Anderson, D.E.

    2007-01-01

    CO2 transport processes relevant for estimating net ecosystem exchange (NEE) at the Niwot Ridge AmeriFlux site in the front range of the Rocky Mountains, Colorado, USA, were investigated during a pilot experiment. We found that cold, moist, and CO2-rich air was transported downslope at night and upslope in the early morning at this forest site situated on a ???5% east-facing slope. We found that CO2 advection dominated the total CO2 transport in the NEE estimate at night although there are large uncertainties because of partial cancellation of horizontal and vertical advection. The horizontal CO2 advection captured not only the CO2 loss at night, but also the CO2 uptake during daytime. We found that horizontal CO2 advection was significant even during daytime especially when turbulent mixing was not significant, such as in early morning and evening transition periods and within the canopy. Similar processes can occur anywhere regardless of whether flow is generated by orography, synoptic pressure gradients, or surface heterogeneity as long as CO2 concentration is not well mixed by turbulence. The long-term net effect of all the CO2 budget terms on estimates of NEE needs to be investigated. ?? 2007 Elsevier B.V. All rights reserved.

  1. Covalent Organic Frameworks for CO2 Capture.

    PubMed

    Zeng, Yongfei; Zou, Ruqiang; Zhao, Yanli

    2016-04-20

    As an emerging class of porous crystalline materials, covalent organic frameworks (COFs) are excellent candidates for various applications. In particular, they can serve as ideal platforms for capturing CO2 to mitigate the dilemma caused by the greenhouse effect. Recent research achievements using COFs for CO2 capture are highlighted. A background overview is provided, consisting of a brief statement on the current CO2 issue, a summary of representative materials utilized for CO2 capture, and an introduction to COFs. Research progresses on: i) experimental CO2 capture using different COFs synthesized based on different covalent bond formations, and ii) computational simulation results of such porous materials on CO2 capture are summarized. Based on these experimental and theoretical studies, careful analyses and discussions in terms of the COF stability, low- and high-pressure CO2 uptake, CO2 selectivity, breakthrough performance, and CO2 capture conditions are provided. Finally, a perspective and conclusion section of COFs for CO2 capture is presented. Recent advancements in the field are highlighted and the strategies and principals involved are discussed.

  2. Energyless CO2 Absorption, Generation, and Fixation Using Atmospheric CO2.

    PubMed

    Inagaki, Fuyuhiko; Okada, Yasuhiko; Matsumoto, Chiaki; Yamada, Masayuki; Nakazawa, Kenta; Mukai, Chisato

    2016-01-01

    From an economic and ecological perspective, the efficient utilization of atmospheric CO2 as a carbon resource should be a much more important goal than reducing CO2 emissions. However, no strategy to harvest CO2 using atmospheric CO2 at room temperature currently exists, which is presumably due to the extremely low concentration of CO2 in ambient air (approximately 400 ppm=0.04 vol%). We discovered that monoethanolamine (MEA) and its derivatives efficiently absorbed atmospheric CO2 without requiring an energy source. We also found that the absorbed CO2 could be easily liberated with acid. Furthermore, a novel CO2 generator enabled us to synthesize a high value-added material (i.e., 2-oxazolidinone derivatives based on the metal catalyzed CO2-fixation at room temperature) from atmospheric CO2.

  3. Exogenously produced CO2 doubles the CO2 efflux from three north temperate lakes

    NASA Astrophysics Data System (ADS)

    Wilkinson, Grace M.; Buelo, Cal D.; Cole, Jonathan J.; Pace, Michael L.

    2016-03-01

    It is well established that lakes are typically sources of CO2 to the atmosphere. However, it remains unclear what portion of CO2 efflux is from endogenously processed organic carbon or from exogenously produced CO2 transported into lakes. We estimated high-frequency CO2 and O2 efflux from three north temperate lakes in summer to determine the proportion of the total CO2 efflux that was exogenously produced. Two of the lakes were amended with nutrients to experimentally enhance endogenous CO2 uptake. In the unfertilized lake, 50% of CO2 efflux was from exogenous sources and hydrology had a large influence on efflux. In the fertilized lakes, endogenous CO2 efflux was negative (into the lake) yet exogenous CO2 made the lakes net sources of CO2 to the atmosphere. Shifts in hydrologic regimes and nutrient loading have the potential to change whether small lakes act primarily as reactors or vents in the watershed.

  4. Second international conference on air-sea interaction and on meteorology and oceanography of the coastal zone

    SciTech Connect

    1994-12-31

    This conference was held September 22--27, 1994 in Lisbon, Portugal. The purpose of this conference was to provide a multidisciplinary forum for exchange of state-of-the-art information on air-sea interactions. Individual papers have been processed separately for inclusion in the appropriate data bases.

  5. Effect of the accumulation of polycyclic aromatic hydrocarbons in the sea surface microlayer on their coastal air-sea exchanges

    NASA Astrophysics Data System (ADS)

    Guitart, C.; García-Flor, N.; Miquel, J. C.; Fowler, S. W.; Albaigés, J.

    2010-01-01

    Several measurements of polycyclic aromatic hydrocarbons (PAHs) in coastal marine compartments (viz. atmosphere, sea surface microlayer, subsurface seawater, sinking particles and sediments), made nearly simultaneously at two stations in the north-eastern Mediterranean, were used to estimate the transport fluxes of individual and total PAHs through the air-seawater-sediment system. Diffusive air-sea exchange fluxes were estimated using both subsurface water (SSW) and sea surface microlayer (SML) concentrations. The air-SML fluxes ranged from 411 to 12,292 ng m - 2 d - 1 (absorption) and from - 506 to -13,746 ng m - 2 d - 1 (volatilisation) for total PAHs (Σ15). Air-seawater column transport of particle-associated PAHs was estimated from the analysis of particulate atmospheric and sediment interceptor trap materials. Air-sea particle deposition fluxes of total PAHs ranged from 13 to 114 ng m - 2 d - 1 and seawater particle settling fluxes (upper 5 m water column) ranged from 184 to 323 ng m - 2 d - 1 . The results of this study indicate that both the magnitude and the direction of the calculated air-sea diffusive fluxes change when PAH concentrations in the SML are considered. As a result, PAHs accumulation in the SML could produce the so-called "flux capping effect". However, the high variability in the coastal air-sea PAHs flux estimations, mainly due to the parameters uncertainty, requires further experimental approaches, including improvement of parameterisations.

  6. Infrared polarization spectroscopy of CO 2 at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Alwahabi, Z. T.; Li, Z. S.; Zetterberg, J.; Aldén, M.

    2004-04-01

    Polarisation spectroscopy (PS) was used to probe CO 2 gas concentration in a CO 2/N 2 binary mixture at atmospheric pressure and ambient temperature. The CO 2 molecules were probed by a direct laser excitation to an overtone and combination vibrational state. The tuneable narrow linewidth infrared laser radiation at 2 μm was obtained by Raman shifting of the output from a single-longitudinal-mode pulsed alexandrite laser-system to the second Stokes component in a H 2 gas cell. Infrared polarisation spectroscopy (IRPS) and time-resolved infrared laser-induced fluorescence (IRLIF) spectra were collected. A linear dependence of the IRPS signal on the CO 2 mole fraction has been found. This indicates that the IRPS signal is only weakly affected by the molecular collisions and that the inter- and intra- molecular energy transfer processes do not strongly influence the molecular alignment at the time scale of the measurements. Thus IRPS holds great potential for quantitative instantaneous gas concentration diagnostics in general. This is especially important for molecules which do not posses an accessible optical transition such as CO, CO 2 and N 2O. In addition, an accurate experimental method to measure the extinction ratio of the IR polarisers employed in this study has been developed and applied. With its obvious merits as simplicity, easy alignment and high accuracy, the method can be generalized to all spectral regions, different polarisers and high extinction ratios.

  7. Effect of sea sprays on air-sea momentum exchange at severe wind conditions

    NASA Astrophysics Data System (ADS)

    Troitskaya, Yu.; Ezhova, E.; Semenova, A.; Soustova, I.

    2012-04-01

    Wind-wave interaction at extreme wind speed is of special interest now in connection with the problem of explanation of the sea surface drag saturation at the wind speed exceeding 30 m/s. The idea on saturation (and even reduction) of the coefficient of aerodynamic resistance of the sea surface at hurricane wind speed was first suggested in [1] on the basis of theoretical analysis of sensitivity of maximum wind speed in a hurricane to the ratio of the enthalpy and momentum exchange coefficients. Both field [2-4] and laboratory [5] experiments confirmed that at hurricane wind speed the sea surface drag coefficient is significantly reduced in comparison with the parameterization obtained at moderate to strong wind conditions. Two groups of possible theoretical mechanisms for explanation of the effect of the sea surface drag reduction can be specified. In the first group of models developed in [6,7], the sea surface drag reduction is explained by peculiarities of the air flow over breaking waves. Another approach more appropriate for the conditions of developed sea exploits the effect of sea drops and sprays on the wind-wave momentum exchange. Papers[8,9] focused on the effect of the sea drops on stratification of the air-sea boundary layer similar to the model of turbulent boundary layer with the suspended particles [10], while papers [11-13] estimated the momentum exchange of sea drops and air-flow. A mandatory element of the spray induced momentum flux is a parameterization of the momentum exchange between droplets and air flow, which determines the "source function" in the momentum balance equation. In this paper a model describing the motion of a spume droplet, the wind tear away from the crest of a steep surface wave, and then falling into the water. We consider two models for the injection of droplets into the air flow. The first one assumes that the drop starts from the surface at the orbital velocity of the wave. In the second model we consider droplets from

  8. Modeling of collision induced absorption spectra of CO2-CO2 pairs for planetary atmosphere of Venus

    NASA Technical Reports Server (NTRS)

    Borysow, Aleksandra

    1995-01-01

    The objective of the proposal was to model the rototranslational and rotovibrational collision induced absorption spectral bands of importance for the radiative transfer analysis of the atmosphere of Venus. Our main task has involved CO2 pairs. The approach is not straightforward: whereas computational techniques to compute CIA spectra of small linear molecules exist, and were successfully applied to molecules like H2 or N2, they fail when applied to large molecules like CO2. For small molecules one can safely assume that the interaction potential is isotropic. The same approximation does not work for CO2, and when employed, it gives an incorrect band shape and only 50 percent of the CIA intensity.

  9. European source and sink areas of CO2 retrieved from Lagrangian transport model interpretation of combined O2 and CO2 measurements at the high alpine research station Jungfraujoch

    NASA Astrophysics Data System (ADS)

    Uglietti, C.; Leuenberger, M.; Brunner, D.

    2011-08-01

    The University of Bern monitors carbon dioxide (CO2) and oxygen (O2) at the High Altitude Research Station Jungfraujoch since the year 2000 by means of flasks sampling and since 2005 using a continuous in situ measurement system. This study investigates the transport of CO2 and O2 towards Jungfraujoch using backward Lagrangian Particle Dispersion Model (LPDM) simulations and utilizes CO2 and O2 signatures to classify air masses. By investigating the simulated transport patterns associated with distinct CO2 concentrations it is possible to decipher different source and sink areas over Europe. The highest CO2 concentrations, for example, were observed in winter during pollution episodes when air was transported from Northeastern Europe towards the Alps, or during south Foehn events with rapid uplift of polluted air from Northern Italy, as demonstrated in two case studies. To study the importance of air-sea exchange for variations in O2 concentrations at Jungfraujoch the correlation between CO2 and APO (Atmospheric Potential Oxygen) deviations from a seasonally varying background was analyzed. Anomalously high APO concentrations were clearly associated with air masses originating from the Atlantic Ocean, whereas low APO concentrations were found in air masses advected either from the east from the Eurasian continent in summer, or from the Eastern Mediterranean in winter. Those air masses with low APO in summer were also strongly depleted in CO2 suggesting a combination of CO2 uptake by vegetation and O2 uptake by dry summer soils. Other subsets of points in the APO-CO2 scatter plot investigated with respect to air mass origin included CO2 and APO background values and points with regular APO but anomalous CO2 concentrations. Background values were associated with free tropospheric air masses with little contact with the boundary layer during the last few days, while high or low CO2 concentrations reflect the various levels of influence of anthropogenic emissions and

  10. Trialkylborane-Assisted CO(2) Reduction by Late Transition Metal Hydrides.

    PubMed

    Miller, Alexander J M; Labinger, Jay A; Bercaw, John E

    2011-01-01

    Trialkylborane additives promote reduction of CO(2) to formate by bis(diphosphine) Ni(II) and Rh(III) hydride complexes. The late transition metal hydrides, which can be formed from dihydrogen, transfer hydride to CO(2) to give a formate-borane adduct. The borane must be of appropriate Lewis acidity: weaker acids do not show significant hydride transfer enhancement, while stronger acids abstract hydride without CO(2) reduction. The mechanism likely involves a pre-equilibrium hydride transfer followed by formation of a stabilizing formate-borane adduct.

  11. Key site abandonment steps in CO2 storage

    NASA Astrophysics Data System (ADS)

    Kühn, M.; Wipki, M.; Durucan, S.; Deflandre, J.-P.; Lüth, S.; Wollenweber, J.; Chadwick, A.; Böhm, G.

    2012-04-01

    CO2CARE is an EU funded project within FP7-research, which started in January 2011 with a funding period of three years. The project objectives will be achieved through an international consortium consisting of 23 partners from Europe, USA, Canada, Japan, and Australia, belonging to universities, research institutes, and energy companies. According to the EC Guidance Document 3, the lifetime of a CO2 storage site can be generally subdivided into 6 phases: 1. assessment, 2. characterisation, 3. development, 4. operation, 5. post-closure/pre-transfer, and 6. post transfer. CO2CARE deals with phases 5 and 6. The main goals of the project are closely linked to the three high-level requirements of the EU Directive 2009/31/EC, Article 18 for CO2 storage which are: (i) absence of any detectable leakage, (ii) conformity of actual behaviour of the injected CO2 with the modelled behaviour, and (iii) the storage site is evolving towards a situation of long-term stability. These criteria have to be fulfilled prior to subsequent transfer of responsibility to the competent authorities, typically 20 or 30 years after site closure. CO2CARE aims to formulate robust procedures for site abandonment which will meet the regulatory requirements and ensure long-term integrity of the storage complex. We present key results from the first year of the project via a report on international regulatory requirements on CO2 geological storage and site abandonment that includes a general overview on the current state-of-the art in abandonment methodologies in the oil and gas industry worldwide. Due to the long time-frames involved in CO2 storage (in the range of several thousands of years), the behaviour of a system with respect to, for example, long-term well stability can be demonstrated only by using long-term predictive modelling tools to study potential leakage pathways. Trapping mechanisms for CO2 are of high interest concerning a quantitative estimation of physically captured, capillary

  12. Catalytic Reduction of CO2 by Renewable Organohydrides.

    PubMed

    Lim, Chern-Hooi; Holder, Aaron M; Hynes, James T; Musgrave, Charles B

    2015-12-17

    Dihydropyridines are renewable organohydride reducing agents for the catalytic reduction of CO2 to MeOH. Here we discuss various aspects of this important reduction. A centerpiece, which illustrates various general principles, is our theoretical catalytic mechanism for CO2 reduction by successive hydride transfers (HTs) and proton transfers (PTs) from the dihydropyridine PyH2 obtained by 1H(+)/1e(-)/1H(+)/1e(-) reductions of pyridine. The Py/PyH2 redox couple is analogous to NADP(+)/NADPH in that both are driven to effect HTs by rearomatization. High-energy radical intermediates and their associated high barriers/overpotentials are avoided because HT involves a 2e(-) reduction. A HT-PT sequence dictates that the reduced intermediates be protonated prior to further reduction for ultimate MeOH formation; these protonations are aided by biased cathodes that significantly lower the local pH. In contrast, cathodes that efficiently reduce H(+) such as Pt and Pd produce H2 and create a high interfacial pH, both obstructing dihydropyridine production and formate protonation and thus ultimately CO2 reduction by HTPTs. The role of water molecule proton relays is discussed. Finally, we suggest future CO2 reduction strategies by organic (photo)catalysts.

  13. CO2 sequestration: Storage capacity guideline needed

    USGS Publications Warehouse

    Frailey, S.M.; Finley, R.J.; Hickman, T.S.

    2006-01-01

    Petroleum reserves are classified for the assessment of available supplies by governmental agencies, management of business processes for achieving exploration and production efficiency, and documentation of the value of reserves and resources in financial statements. Up to the present however, the storage capacity determinations made by some organizations in the initial CO2 resource assessment are incorrect technically. New publications should thus cover differences in mineral adsorption of CO2 and dissolution of CO2 in various brine waters.

  14. Nocturnal intermittency in surface CO2 concentrations in sub-Saharan Africa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Data obtained over four adjacent fields of differing management practices in Zimbabwe illustrate the role of atmospheric intermittency as a mechanism for transferring CO2 between the surface and the atmosphere above. At night, limited atmospheric mixing permits CO2 concentrations to increase to leve...

  15. R&D100: CO2 Memzyme

    SciTech Connect

    Rempe, Susan; Brinker, Jeff; Jiang, Ying-Bing; Vanegas, Juan

    2015-11-19

    By combining a water droplet loaded with CO2 enzymes in an ultrathin nanopore on a flexible substrate, researchers at Sandia National Laboratories realized the first technology that meets and exceeds DOE targets for cost-effective CO2 capture. When compared with the nearest membrane competitor, this technology delivers a three times permeation rate, twenty times higher selectivity, and ten time lower fabrication cost. The CO2 Memzyme has the potential to remove 90% of CO2 emissions and is forecasted to save the U.S. coal industry $90 billion a year compared to conventional technology.

  16. Synthetic biology for CO2 fixation.

    PubMed

    Gong, Fuyu; Cai, Zhen; Li, Yin

    2016-11-01

    Recycling of carbon dioxide (CO2) into fuels and chemicals is a potential approach to reduce CO2 emission and fossil-fuel consumption. Autotrophic microbes can utilize energy from light, hydrogen, or sulfur to assimilate atmospheric CO2 into organic compounds at ambient temperature and pressure. This provides a feasible way for biological production of fuels and chemicals from CO2 under normal conditions. Recently great progress has been made in this research area, and dozens of CO2-derived fuels and chemicals have been reported to be synthesized by autotrophic microbes. This is accompanied by investigations into natural CO2-fixation pathways and the rapid development of new technologies in synthetic biology. This review first summarizes the six natural CO2-fixation pathways reported to date, followed by an overview of recent progress in the design and engineering of CO2-fixation pathways as well as energy supply patterns using the concept and tools of synthetic biology. Finally, we will discuss future prospects in biological fixation of CO2.

  17. CO2 capture in different carbon materials.

    PubMed

    Jiménez, Vicente; Ramírez-Lucas, Ana; Díaz, José Antonio; Sánchez, Paula; Romero, Amaya

    2012-07-03

    In this work, the CO(2) capture capacity of different types of carbon nanofibers (platelet, fishbone, and ribbon) and amorphous carbon have been measured at 26 °C as at different pressures. The results showed that the more graphitic carbon materials adsorbed less CO(2) than more amorphous materials. Then, the aim was to improve the CO(2) adsorption capacity of the carbon materials by increasing the porosity during the chemical activation process. After chemical activation process, the amorphous carbon and platelet CNFs increased the CO(2) adsorption capacity 1.6 times, whereas fishbone and ribbon CNFs increased their CO(2) adsorption capacity 1.1 and 8.2 times, respectively. This increase of CO(2) adsorption capacity after chemical activation was due to an increase of BET surface area and pore volume in all carbon materials. Finally, the CO(2) adsorption isotherms showed that activated amorphous carbon exhibited the best CO(2) capture capacity with 72.0 wt % of CO(2) at 26 °C and 8 bar.

  18. R&D100: CO2 Memzyme

    ScienceCinema

    Rempe, Susan; Brinker, Jeff; Jiang, Ying-Bing; Vanegas, Juan

    2016-07-12

    By combining a water droplet loaded with CO2 enzymes in an ultrathin nanopore on a flexible substrate, researchers at Sandia National Laboratories realized the first technology that meets and exceeds DOE targets for cost-effective CO2 capture. When compared with the nearest membrane competitor, this technology delivers a three times permeation rate, twenty times higher selectivity, and ten time lower fabrication cost. The CO2 Memzyme has the potential to remove 90% of CO2 emissions and is forecasted to save the U.S. coal industry $90 billion a year compared to conventional technology.

  19. CO2 MITIGATION VIA ACCELERATED LIMESTONE WEATHERING

    SciTech Connect

    Rau, G H; Knauss, K G; Langer, W H; Caldeira, K G

    2004-02-27

    The climate and environmental impacts of our current, carbon-intensive energy usage demands that effective and practical energy alternatives and CO2 mitigation strategies be found. As part of this effort, various means of capturing and storing CO2 generated from fossil-fuel-based energy production are being investigated. One of the proposed methods involves a geochemistry-based capture and sequestration process that hydrates point-source, waste CO2 with water to produce a carbonic acid solution. This in turn is reacted and neutralized with limestone, thus converting the original CO2 gas to calcium bicarbonate in solution, the overall reaction being:

  20. Shaft sealing issue in CO2 storage sites

    NASA Astrophysics Data System (ADS)

    Dieudonné, A.-C.; Charlier, R.; Collin, F.

    2012-04-01

    Carbon capture and storage is an innovating approach to tackle climate changes through the reduction of greenhouse gas emissions. Deep saline aquifers, depleted oil and gas reservoirs and unmineable coal seams are among the most studied reservoirs. However other types of reservoir, such as abandonned coal mines, could also be used for the storage of carbon dioxide. In this case, the problem of shaft sealing appears to be particularly critical regarding to the economic, ecologic and health aspects of geological storage. The purpose of the work is to study shaft sealing in the framework of CO2 storage projects in abandoned coal mines. The problem of gas transfers around a sealing system is studied numerically using the finite elements code LAGAMINE, which has been developped for 30 years at the University of Liege. A coupled hydro-mechanical model of unsaturated geomaterials is used for the analyses. The response of the two-phase flow model is first studied through a simple synthetic problem consisting in the injection of gas in a concrete-made column. It stands out of this first modeling that the advection of the gas phase represents the main transfer mechanism of CO2 in highly unsaturated materials. Furthermore the setting of a bentonite barrier seal limits considerably the gas influx into the biosphere. A 2D axisymetric hydromechanical modeling of the Anderlues natural gas storage site is then performed. The geological and hydrogeological contexts of the site are used to define the problem, for the initial and boundary conditions, as well as the material properties. In order to reproduce stress and water saturation states in the shale before CO2 injection in the mine, different phases corresponding to the shaft sinking, the mining and the set up of the sealing system are simulated. The system efficiency is then evaluated by simulating the CO2 injection with the imposed pressure at the shaft wall. According to the modeling, the low water saturation of concrete and

  1. CO2 Interaction with Geomaterials (Invited)

    NASA Astrophysics Data System (ADS)

    Romanov, V.; Howard, B. H.; Lynn, R. J.; Warzinski, R. P.; Hur, T.; Myshakin, E. M.; Lopano, C. L.; Voora, V. K.; Al-Saidi, W. A.; Jordan, K. D.; Cygan, R. T.; Guthrie, G. D.

    2010-12-01

    This work compares the sorption and swelling processes associated with CO2-coal and CO2-clay interactions. We investigated the mechanisms of interaction related to CO2 adsortion in micropores, intercalation into sub-micropores, dissolution in solid matrix, the role of water, and the associated changes in reservoir permeability, for applications in CO2 sequestration and enhanced coal bed methane recovery. The structural changes caused by CO2 have been investigated. A high-pressure micro-dilatometer was equipped to investigate the effect of CO2 pressure on the thermoplastic properties of coal. Using an identical dilatometer, Rashid Khan (1985) performed experiments with CO2 that revealed a dramatic reduction in the softening temperature of coal when exposed to high-pressure CO2. A set of experiments was designed for -20+45-mesh samples of Argonne Premium Pocahontas #3 coal, which is similar in proximate and ultimate analysis to the Lower Kittanning seam coal that Khan used in his experiments. No dramatic decrease in coal softening temperature has been observed in high-pressure CO2 that would corroborate the prior work of Khan. Thus, conventional polymer (or “geopolymer”) theories may not be directly applicable to CO2 interaction with coals. Clays are similar to coals in that they represent abundant geomaterials with well-developed microporous structure. We evaluated the CO2 sequestration potential of clays relative to coals and investigated the factors that affect the sorption capacity, rates, and permanence of CO2 trapping. For the geomaterials comparison studies, we used source clay samples from The Clay Minerals Society. Preliminary results showed that expandable clays have CO2 sorption capacities comparable to those of coal. We analyzed sorption isotherms, XRD, DRIFTS (infrared reflectance spectra at non-ambient conditions), and TGA-MS (thermal gravimetric analysis) data to compare the effects of various factors on CO2 trapping. In montmorillonite, CO2

  2. Electronic spectroscopy and photodissociation dynamics of Co(2+)-methanol clusters: Co2+ (CH3OH)n (n = 4-7).

    PubMed

    Thompson, Christopher J; Faherty, Kieron P; Stringer, Kay L; Metz, Ricardo B

    2005-03-07

    Solvated cluster ions Co2+ (CH3OH)n (n = 4-7) have been produced by electrospray and studied using photofragment spectroscopy. There are notable differences between the photodissociation spectra of these complexes and the analogous water complexes. Co2+ (CH3OH)6 absorbs significantly more strongly than Co2+ (H2O)6. The photodissociation spectra of Co2+ (CH3OH)n (n = 4, 5 and 6) are very similar, which suggests that they share the Co2+ (CH3OH)4 chromophore, with additional solvent molecules in the second shell. In contrast, our earlier studies indicate that Co2+ (H2O)6 is six coordinate, and its spectrum is significantly different from that of Co2+ (H2O)4. The larger clusters Co2+ (CH3OH)n (n = 5-7) dissociate by simple loss of one or more solvent molecules. Larger clusters tend to lose more solvent molecules, especially at higher photon energies. As with the corresponding water cluster, Co2+ (CH3OH)4 photodissociates by proton transfer through a salt-bridge intermediate. This is accompanied by a modest kinetic energy release of 170 kJ mol(-1) and occurs with a lifetime of 145 ns.

  3. Sites of action of elevated CO2 on leaf development in rice: discrimination between the effects of elevated CO2 and nitrogen deficiency.

    PubMed

    Tsutsumi, Koichi; Konno, Masae; Miyazawa, Shin-Ichi; Miyao, Mitsue

    2014-02-01

    Elevated CO2 concentrations (eCO2) trigger various plant responses. Despite intensive studies of these responses, the underlying mechanisms remain obscure. In this work, we investigated when and how leaf physiology and anatomy are affected by eCO2 in rice plants. We analyzed the most recently fully expanded leaves that developed successively after transfer of the plant to eCO2. To discriminate between the effects of eCO2 and those of nitrogen deficiency, we used three different levels of N application. We found that a decline in the leaf soluble protein content (on a leaf area basis) at eCO2 was only observed under N deficiency. The length and width of the leaf blade were reduced by both eCO2 and N deficiency, whereas the blade thickness was increased by eCO2 but was not affected by N deficiency. The change in length by eCO2 became detectable in the secondly fully expanded leaf, and those in width and thickness in the thirdly fully expanded leaf, which were at the leaf developmental stages P4 and P3, respectively, at the onset of the eCO2 treatment. The decreased blade length at eCO2 was associated with a decrease in the epidermal cell number on the adaxial side and a reduction in cell length on the abaxial side. The decreased width resulted from decreased numbers of small vascular bundles and epidermal cell files. The increased thickness was ascribed mainly to enhanced development of bundle sheath extensions at the ridges of vascular bundles. These observations enable us to identify the sites of action of eCO2 on rice leaf development.

  4. Changes in the Arctic Ocean CO2 sink (1996-2007): A regional model analysis

    NASA Astrophysics Data System (ADS)

    Manizza, M.; Follows, M. J.; Dutkiewicz, S.; Menemenlis, D.; Hill, C. N.; Key, R. M.

    2013-12-01

    The rapid recent decline of Arctic Ocean sea ice area increases the flux of solar radiation available for primary production and the area of open water for air-sea gas exchange. We use a regional physical-biogeochemical model of the Arctic Ocean, forced by the National Centers for Environmental Prediction/National Center for Atmospheric Research atmospheric reanalysis, to evaluate the mean present-day CO2 sink and its temporal evolution. During the 1996-2007 period, the model suggests that the Arctic average sea surface temperature warmed by 0.04°C a-1, that sea ice area decreased by ˜0.1 × 106 km2 a-1, and that the biological drawdown of dissolved inorganic carbon increased. The simulated 1996-2007 time-mean Arctic Ocean CO2 sink is 58 ± 6 Tg C a-1. The increase in ice-free ocean area and consequent carbon drawdown during this period enhances the CO2 sink by ˜1.4 Tg C a-1, consistent with estimates based on extrapolations of sparse data. A regional analysis suggests that during the 1996-2007 period, the shelf regions of the Laptev, East Siberian, Chukchi, and Beaufort Seas experienced an increase in the efficiency of their biological pump due to decreased sea ice area, especially during the 2004-2007 period, consistent with independently published estimates of primary production. In contrast, the CO2 sink in the Barents Sea is reduced during the 2004-2007 period due to a dominant control by warming and decreasing solubility. Thus, the effect of decreasing sea ice area and increasing sea surface temperature partially cancel, though the former is dominant.

  5. Dependence of global temperatures on atmospheric CO2 and solar irradiance

    PubMed Central

    Thomson, David J.

    1997-01-01

    Changes in global average temperatures and of the seasonal cycle are strongly coupled to the concentration of atmospheric CO2. I estimate transfer functions from changes in atmospheric CO2 and from changes in solar irradiance to hemispheric temperatures that have been corrected for the effects of precession. They show that changes from CO2 over the last century are about three times larger than those from changes in solar irradiance. The increase in global average temperature during the last century is at least 20 times the SD of the residual temperature series left when the effects of CO2 and changes in solar irradiance are subtracted. PMID:11607747

  6. Extreme subseasonal tropical air-sea interactions and their relation to ocean thermal stratification

    NASA Astrophysics Data System (ADS)

    Lloyd, Ian D.

    2011-12-01

    This thesis is concerned with extreme, rapid timescale tropical air-sea interactions and the influence of large-scale oceanic conditions on these interactions. The focus is on two types of extreme events: equatorial Indian Ocean cooling events and tropical cyclones. Cooling events occur on timescales of a few days to several weeks, in which atmospheric forcing causes Sea Surface Temperature (SST) cooling in the range of 1--5K, in both observational and coupled climate models. Cooling events are driven by changes in air-sea enthalpy fluxes and Ekman upwelling. Because the cooling due to Ekman upwelling depends on thermocline depth, large-scale oceanic conditions influence SST cooling. La Nina and negative Indian Ocean Dipole conditions are conducive to a shallower southwest equatorial thermocline, resulting in greater intraseasonal SST cooling during these interannual events; El Nino and positive Indian Ocean Dipole conditions lead to a deeper thermocline and reduced SST cooling. Results indicate that cooling events are related to the eastward propagation of convective patterns that resemble the Madden-Julian Oscillation. For tropical cyclones, the response of intensity to cyclone-induced SST cooling was explored over 10-years of observational data. For slow moving (V/ f < 100km) tropical cyclones, it was found that the SST cooling response increases along with storm intensity from category 0--2 on the Saffir-Simpson scale. However, from category 2--5 the magnitude of SST cooling decreases. This result confirms model predictions indicating a prominent role for oceanic feedback controlling tropical cyclone intensity. Thus, only storms that develop in regions containing deep mixed layer and thermocline can achieve high intensity, and entrainment cooling is weaker for these storms. The SST-intensity response in observations was compared to the GFDL Hurricane Forecast Model (GHM) for the periods 2005 and 2006--2009. The GHM was modified in 2006 to include a

  7. Estimating the monthly pCO2 distribution in the North Atlantic using a self-organizing neural network

    NASA Astrophysics Data System (ADS)

    Telszewski, M.; Chazottes, A.; Schuster, U.; Watson, A. J.; Moulin, C.; Bakker, D. C. E.; González-Dávila, M.; Johannessen, T.; Körtzinger, A.; Lüger, H.; Olsen, A.; Omar, A.; Padin, X. A.; Ríos, A. F.; Steinhoff, T.; Santana-Casiano, M.; Wallace, D. W. R.; Wanninkhof, R.

    2009-08-01

    Here we present monthly, basin-wide maps of the partial pressure of carbon dioxide (pCO2) for the North Atlantic on a 1° latitude by 1° longitude grid for years 2004 through 2006 inclusive. The maps have been computed using a neural network technique which reconstructs the non-linear relationships between three biogeochemical parameters and marine pCO2. A self organizing map (SOM) neural network has been trained using 389 000 triplets of the SeaWiFS-MODIS chlorophyll-a concentration, the NCEP/NCAR reanalysis sea surface temperature, and the FOAM mixed layer depth. The trained SOM was labelled with 137 000 underway pCO2 measurements collected in situ during 2004, 2005 and 2006 in the North Atlantic, spanning the range of 208 to 437 μatm. The root mean square error (RMSE) of the neural network fit to the data is 11.6 μatm, which equals to just above 3 per cent of an average pCO2 value in the in situ dataset. The seasonal pCO2 cycle as well as estimates of the interannual variability in the major biogeochemical provinces are presented and discussed. High resolution combined with basin-wide coverage makes the maps a useful tool for several applications such as the monitoring of basin-wide air-sea CO2 fluxes or improvement of seasonal and interannual marine CO2 cycles in future model predictions. The method itself is a valuable alternative to traditional statistical modelling techniques used in geosciences.

  8. Estimating the monthly pCO2 distribution in the North Atlantic using a self-organizing neural network

    NASA Astrophysics Data System (ADS)

    Telszewski, M.; Chazottes, A.; Schuster, U.; Watson, A. J.; Moulin, C.; Bakker, D. C. E.; González-Dávila, M.; Johannessen, T.; Körtzinger, A.; Lüger, H.; Olsen, A.; Omar, A.; Padin, X. A.; Ríos, A.; Steinhoff, T.; Santana-Casiano, M.; Wallace, D. W. R.; Wanninkhof, R.

    2009-03-01

    Here we present monthly, basin-wide maps of the partial pressure of carbon dioxide (pCO2) for the North Atlantic on a 1° latitude by 1° longitude grid for years 2004 through 2006 inclusive, constructed using a neural network technique which reconstructs the non-linear relationships between 3 biogeochemical parameters and marine pCO2. A self organizing map (SOM) neural network has been trained using the SeaWiFS-MODIS chlorophyll a concentration, the NCEP/NCAR reanalysis sea surface temperature, and the FOAM mixed layer depth. 389 000 such triplets were used. The trained SOM was labelled with 137 000 underway pCO2 measurements collected in situ during 2004, 2005 and 2006 in the North Atlantic, which span the range of 208 and 437 μatm. The root mean square (RMS) deviation of the neural network fits from the data is 11.55 μatm, which equals to just above 3 per cent of an average pCO2 value in the in situ dataset. The seasonal pCO2 cycle as well as the interannual variability estimates in the major biogeochemical provinces is presented and spatial and temporal variability of the estimated fields is discussed. High resolution combined with basin-wide cover makes the maps a useful tool for several applications such as monitoring of basin-wide air-sea CO2 fluxes or improvement of seasonal and interannual marine CO2 cycles in future model predictions. The method itself is a valuable alternative to traditional statistical modelling techniques used in geosciences.

  9. Quantifying the "chamber effect" in CO2 flux measurements

    NASA Astrophysics Data System (ADS)

    Vihermaa, Leena; Childs, Amy; Long, Hazel; Waldron, Susan

    2014-05-01

    The significance of aquatic CO2 emissions has received attention in recent years. For example annual aquatic emissions in the Amazon basin have been estimated as 500 Mt of carbon1. Methods for determining the flux rates include eddy covariance flux tower measurements, flux estimates calculated from partial pressure of CO2 (pCO2) in water and the use floating flux chambers connected to an infra-red gas analyser. The flux chamber method is often used because it is portable, cheaper and allows smaller scale measurements. It is also a direct method and hence avoids problems related to the estimation of the gas transfer coefficient that is required when fluxes are calculated from pCO2. However, the use of a floating chamber may influence the flux measurements obtained. The chamber shields the water underneath from effects of wind which could lead to lower flux estimates. Wind increases the flux rate by i) causing waves which increase the surface area for efflux, and ii) removing CO2 build up above the water surface, hence maintaining a higher concentration gradient. Many floating chambers have an underwater extension of the chamber below the float to ensure better seal to water surface and to prevent any ingress of atmospheric air when waves rock the chamber. This extension may cause additional turbulence in flowing water and hence lead to overestimation of flux rates. Some groups have also used a small fan in the chamber headspace to ensure thorough mixing of air in the chamber. This may create turbulence inside the chamber which could increase the flux rate. Here we present results on the effects of different chamber designs on the detected flux rates. 1Richey et al. 2002. Outgassing from Amazonian rivers and wetlands as a large tropical source of atmospheric CO2. Nature 416: 617-620.

  10. Capturing CO2 via reactions in nanopores.

    SciTech Connect

    Leung, Kevin; Nenoff, Tina Maria; Criscenti, Louise Jacqueline; Tang, Z; Dong, J. H.

    2008-10-01

    This one-year exploratory LDRD aims to provide fundamental understanding of the mechanism of CO2 scrubbing platforms that will reduce green house gas emission and mitigate the effect of climate change. The project builds on the team members expertise developed in previous LDRD projects to study the capture or preferential retention of CO2 in nanoporous membranes and on metal oxide surfaces. We apply Density Functional Theory and ab initio molecular dynamics techniques to model the binding of CO2 on MgO and CaO (100) surfaces and inside water-filled, amine group functionalized silica nanopores. The results elucidate the mechanisms of CO2 trapping and clarify some confusion in the literature. Our work identifies key future calculations that will have the greatest impact on CO2 capture technologies, and provides guidance to science-based design of platforms that can separate the green house gas CO2 from power plant exhaust or even from the atmosphere. Experimentally, we modify commercial MFI zeolite membranes and find that they preferentially transmit H2 over CO2 by a factor of 34. Since zeolite has potential catalytic capability to crack hydrocarbons into CO2 and H2, this finding paves the way for zeolite membranes that can convert biofuel into H2 and separate the products all in one step.

  11. CO2 Capture with Enzyme Synthetic Analogue

    SciTech Connect

    Cordatos, Harry

    2010-03-01

    Project overview provides background on carbonic anhydrase transport mechanism for CO2 in the human body and proposed approach for ARPA-E project to create a synthetic enzyme analogue and utilize it in a membrane for CO2 capture from flue gas.

  12. CO2 Capture with Enzyme Synthetic Analogue

    SciTech Connect

    Cordatos, Harry

    2010-11-08

    Overview of an ongoing, 2 year research project partially funded by APRA-E to create a novel, synthetic analogue of carbonic anhydrase and incorporate it into a membrane for removal of CO2 from flue gas in coal power plants. Mechanism background, preliminary feasibility study results, molecular modeling of analogue-CO2 interaction, and program timeline are provided.

  13. Improved Criteria for Increasing CO2 Storage Potential with CO2 Enhanced Oil Recovery

    NASA Astrophysics Data System (ADS)

    Bauman, J.; Pawar, R.

    2013-12-01

    In recent years it has been found that deployment of CO2 capture and storage technology at large scales will be difficult without significant incentives. One of the technologies that has been a focus in recent years is CO2 enhanced oil/gas recovery, where additional hydrocarbon recovery provides an economic incentive for deployment. The way CO2 EOR is currently deployed, maximization of additional oil production does not necessarily lead to maximization of stored CO2, though significant amounts of CO2 are stored regardless of the objective. To determine the potential of large-scale CO2 storage through CO2 EOR, it is necessary to determine the feasibility of deploying this technology over a wide range of oil/gas field characteristics. In addition it is also necessary to accurately estimate the ultimate CO2 storage potential and develop approaches that optimize oil recovery along with long-term CO2 storage. This study uses compositional reservoir simulations to further develop technical screening criteria that not only improve oil recovery, but maximize CO2 storage during enhanced oil recovery operations. Minimum miscibility pressure, maximum oil/ CO2 contact without the need of significant waterflooding, and CO2 breakthrough prevention are a few key parameters specific to the technical aspects of CO2 enhanced oil recovery that maximize CO2 storage. We have developed reduced order models based on simulation results to determine the ultimate oil recovery and CO2 storage potential in these formations. Our goal is to develop and demonstrate a methodology that can be used to determine feasibility and long-term CO2 storage potential of CO2 EOR technology.

  14. Geophysical monitoring technology for CO2 sequestration

    NASA Astrophysics Data System (ADS)

    Ma, Jin-Feng; Li, Lin; Wang, Hao-Fan; Tan, Ming-You; Cui, Shi-Ling; Zhang, Yun-Yin; Qu, Zhi-Peng; Jia, Ling-Yun; Zhang, Shu-Hai

    2016-06-01

    Geophysical techniques play key roles in the measuring, monitoring, and verifying the safety of CO2 sequestration and in identifying the efficiency of CO2-enhanced oil recovery. Although geophysical monitoring techniques for CO2 sequestration have grown out of conventional oil and gas geophysical exploration techniques, it takes a long time to conduct geophysical monitoring, and there are many barriers and challenges. In this paper, with the initial objective of performing CO2 sequestration, we studied the geophysical tasks associated with evaluating geological storage sites and monitoring CO2 sequestration. Based on our review of the scope of geophysical monitoring techniques and our experience in domestic and international carbon capture and sequestration projects, we analyzed the inherent difficulties and our experiences in geophysical monitoring techniques, especially, with respect to 4D seismic acquisition, processing, and interpretation.

  15. Zinc depolarized electrochemical CO2 concentration

    NASA Technical Reports Server (NTRS)

    Woods, R. R.; Marshall, R. D.; Schubert, F. H.

    1975-01-01

    Two zinc depolarized electrochemical carbon dioxide concentrator concepts were analytically and experimentally evaluated for portable life support system carbon dioxide (CO2) removal application. The first concept, referred to as the zinc hydrogen generator electrochemical depolarized CO2 concentrator, uses a ZHG to generate hydrogen for direct use in an EDC. The second concept, referred to as the zinc/electrochemical depolarized concentrator, uses a standard EDC cell construction modified for use with the Zn anode. The Zn anode is consumed and subsequently regenerated, thereby eliminating the need to supply H2 to the EDC for the CO2 removal process. The evaluation was based primarily on an analytical evaluation of the two ZnDCs at projected end item performance and hardware design levels. Both ZnDC concepts for PLSS CO2 removal application were found to be noncompetitive in both total equivalent launch weight and individual extravehicular activity mission volume when compared to other candidate regenerable PLSS CO2 scrubbers.

  16. Tropical Intraseasonal Air-Sea Exchanges during the 1997 Pacific Warming

    NASA Technical Reports Server (NTRS)

    Sui, C.-H.; Lau, K.-M.; Chou, S.-H.; Wang, Zihou

    1999-01-01

    The Madden Julian Oscillations (MJO) and associated westerly wind (WW) events account for much of the tropical intraseasonal variability (TISV). The TISV has been suggested as an important stochastic forcing that may be one of the underlying causes for the observed irregularities of the El Nino-Southern Oscillation (ENSO). Recent observational studies and theories of interannual to interdecadal-scale variability suggest that ENSO may arise from different mechanisms depending on the basic states. The Pacific warming event of 1997, being associated with a period of strong MJO and WW events, serves as a natural experiment for studying the possible role of TISV in triggering an ENSO event. We have performed a combined statistical and composite analysis of surface WW events based on the assimilated surface wind and sea level pressure for the period of 1980-1993, the SSM/I wind for the period of 1988-1997, and OLR. Results indicates that extratropical forcing contribute significantly to the evolution of MJO and establishment of WW events over the Pacific warm pool. Following the major WW events, there appeared an eastward extension of equatorial warm SST anomalies from the western Pacific warm pool. Such tropical-extratropical interaction is particularly clear in the winter of 96-97 that leads to the recent warming event in 1997/98. From the above discussion, our current study on this subject is based on the hypothesis that 1) there is an enhanced air-sea interaction associated with TISV and the northerly surges from the extratropics in the initial phase of the 97/98 warming event, and 2) the relevant mechanisms are functions of the basic state of the coupled system (in terms of SST distribution and atmospheric mean circulation) that varies at the interannual and interdecadal time scale. We are analyzing the space-time structure of the northerly surges, their association with air-sea fluxes and upper ocean responses during the period of September 1996 to June 1997. The

  17. Carbon dioxide consumption of the microalga Scenedesmus obtusiusculus under transient inlet CO2 concentration variations.

    PubMed

    Cabello, Juan; Morales, Marcia; Revah, Sergio

    2017-04-15

    The extensive microalgae diversity offers considerable versatility for a wide range of biotechnological applications in environmental and production processes. Microalgal cultivation is based on CO2 fixation via photosynthesis and, consequently, it is necessary to evaluate, in a short time and reliable way, the effect of the CO2 gas concentration on the consumption rate and establish the tolerance range of different strains and the amount of inorganic carbon that can be incorporated into biomass in order to establish the potential for industrial scale application. Dynamic experiments allow calculating the short-term microalgal photosynthetic activity of strains in photobioreactors. In this paper, the effect of step-changes in CO2 concentration fed to a 20L bubble column photobioreactor on the CO2 consumption rate of Scenedesmus obtusiusculus was evaluated at different operation times. The highest apparent CO2 consumption rate (336μmolm(-2)s(-1) and 5.6% of CO2) was 6530mgCO2gb(-1)d(-1) and it decreased to 222mgCO2gb(-1)d(-1) when biomass concentration increased of 0.5 to 3.1gbL(-1) and 5.6% of CO2 was fed. For low CO2 concentrations (<3.8%) the pH remained close to the optimal value (7.5 and 8). The CO2 consumption rates show that S. obtusiusculus was not limited by CO2 availability for concentrations above of 3.8%. The CO2 mass balance showed that 90% of the C-CO2 transferred was used for S. obtusiusculus growth.

  18. Biological and physical controls in the Southern Ocean on past millennial-scale atmospheric CO2 changes.

    PubMed

    Gottschalk, Julia; Skinner, Luke C; Lippold, Jörg; Vogel, Hendrik; Frank, Norbert; Jaccard, Samuel L; Waelbroeck, Claire

    2016-05-17

    Millennial-scale climate changes during the last glacial period and deglaciation were accompanied by rapid changes in atmospheric CO2 that remain unexplained. While the role of the Southern Ocean as a 'control valve' on ocean-atmosphere CO2 exchange has been emphasized, the exact nature of this role, in particular the relative contributions of physical (for example, ocean dynamics and air-sea gas exchange) versus biological processes (for example, export productivity), remains poorly constrained. Here we combine reconstructions of bottom-water [O2], export production and (14)C ventilation ages in the sub-Antarctic Atlantic, and show that atmospheric CO2 pulses during the last glacial- and deglacial periods were consistently accompanied by decreases in the biological export of carbon and increases in deep-ocean ventilation via southern-sourced water masses. These findings demonstrate how the Southern Ocean's 'organic carbon pump' has exerted a tight control on atmospheric CO2, and thus global climate, specifically via a synergy of both physical and biological processes.

  19. Biological and physical controls in the Southern Ocean on past millennial-scale atmospheric CO2 changes

    NASA Astrophysics Data System (ADS)

    Gottschalk, Julia; Skinner, Luke C.; Lippold, Jörg; Vogel, Hendrik; Frank, Norbert; Jaccard, Samuel L.; Waelbroeck, Claire

    2016-05-01

    Millennial-scale climate changes during the last glacial period and deglaciation were accompanied by rapid changes in atmospheric CO2 that remain unexplained. While the role of the Southern Ocean as a 'control valve' on ocean-atmosphere CO2 exchange has been emphasized, the exact nature of this role, in particular the relative contributions of physical (for example, ocean dynamics and air-sea gas exchange) versus biological processes (for example, export productivity), remains poorly constrained. Here we combine reconstructions of bottom-water [O2], export production and 14C ventilation ages in the sub-Antarctic Atlantic, and show that atmospheric CO2 pulses during the last glacial- and deglacial periods were consistently accompanied by decreases in the biological export of carbon and increases in deep-ocean ventilation via southern-sourced water masses. These findings demonstrate how the Southern Ocean's 'organic carbon pump' has exerted a tight control on atmospheric CO2, and thus global climate, specifically via a synergy of both physical and biological processes.

  20. The ins and outs of CO2

    PubMed Central

    Raven, John A.; Beardall, John

    2016-01-01

    It is difficult to distinguish influx and efflux of inorganic C in photosynthesizing tissues; this article examines what is known and where there are gaps in knowledge. Irreversible decarboxylases produce CO2, and CO2 is the substrate/product of enzymes that act as carboxylases and decarboxylases. Some irreversible carboxylases use CO2; others use HCO3 –. The relative role of permeation through the lipid bilayer versus movement through CO2-selective membrane proteins in the downhill, non-energized, movement of CO2 is not clear. Passive permeation explains most CO2 entry, including terrestrial and aquatic organisms with C3 physiology and biochemistry, terrestrial C4 plants and all crassulacean acid metabolism (CAM) plants, as well as being part of some mechanisms of HCO3 – use in CO2 concentrating mechanism (CCM) function, although further work is needed to test the mechanism in some cases. However, there is some evidence of active CO2 influx at the plasmalemma of algae. HCO3 – active influx at the plasmalemma underlies all cyanobacterial and some algal CCMs. HCO3 – can also enter some algal chloroplasts, probably as part of a CCM. The high intracellular CO2 and HCO3 – pools consequent upon CCMs result in leakage involving CO2, and occasionally HCO3 –. Leakage from cyanobacterial and microalgal CCMs involves up to half, but sometimes more, of the gross inorganic C entering in the CCM; leakage from terrestrial C4 plants is lower in most environments. Little is known of leakage from other organisms with CCMs, though given the leakage better-examined organisms, leakage occurs and increases the energetic cost of net carbon assimilation. PMID:26466660

  1. Silvering substrates after CO2 snow cleaning

    NASA Astrophysics Data System (ADS)

    Zito, Richard R.

    2005-09-01

    There have been some questions in the astronomical community concerning the quality of silver coatings deposited on substrates that have been cleaned with carbon dioxide snow. These questions center around the possible existence of carbonate ions left behind on the substrate by CO2. Such carbonate ions could react with deposited silver to produce insoluble silver carbonate, thereby reducing film adhesion and reflectivity. Carbonate ions could be produced from CO2 via the following mechanism. First, during CO2 snow cleaning, a small amount of moisture can condense on a surface. This is especially true if the jet of CO2 is allowed to dwell on one spot. CO2 gas can dissolve in this moisture, producing carbonic acid, which can undergo two acid dissociations to form carbonate ions. In reality, it is highly unlikely that charged carbonate ions will remain stable on a substrate for very long. As condensed water evaporates, Le Chatelier's principle will shift the equilibrium of the chain of reactions that produced carbonate back to CO2 gas. Furthermore, the hydration of CO2 reaction of CO2 with H20) is an extremely slow process, and the total dehydrogenation of carbonic acid is not favored. Living tissues that must carry out the equilibration of carbonic acid and CO2 use the enzyme carbonic anhydrase to speed up the reaction by a factor of one million. But no such enzymatic action is present on a clean mirror substrate. In short, the worst case analysis presented below shows that the ratio of silver atoms to carbonate radicals must be at least 500 million to one. The results of chemical tests presented here support this view. Furthermore, film lift-off tests, also presented in this report, show that silver film adhesion to fused silica substrates is actually enhanced by CO2 snow cleaning.

  2. Photogeneration of Hydride Donors and Their Use Toward CO2 Reduction

    SciTech Connect

    Fujita,E.; Muckerman, J.T.; Polyansky, D.E.

    2009-06-07

    Despite substantial effort, no one has succeeded in efficiently producing methanol from CO2 using homogeneous photocatalytic systems. We are pursuing reaction schemes based on a sequence of hydride-ion transfers to carry out stepwise reduction of CO2 to methanol. We are using hydride-ion transfer from photoproduced C-H bonds in metal complexes with bio-inspired ligands (i.e., NADH-like ligands) that are known to store one proton and two electrons.

  3. TES/Aura L2 Carbon Dioxide (CO2) Nadir (TL2CO2N)

    Atmospheric Science Data Center

    2017-02-27

    ... TES/Aura L2 Carbon Dioxide (CO2) Nadir (TL2CO2N) Project Title:  TES Discipline:  Tropospheric ... Earth Science Atmosphere Atmospheric Chemistry/Carbon and Hydrocarbon Compounds Order Data:  ...

  4. A usage of CO2 hydrate: convenient method to increase CO2 concentration in culturing algae.

    PubMed

    Nakano, Sho; Chang, Kwang-Hyeon; Shijima, Atsushi; Miyamoto, Hiroyuki; Sato, Yukio; Noto, Yuji; Ha, Jin-Yong; Sakamoto, Masaki

    2014-11-01

    The addition of CO2 to algal culture systems can increase algal biomass effectively. Generally, gas bubbling is used to increase CO2 levels in culture systems; however, it is difficult to quantitatively operate to control the concentration using this method. In this study, we tested the usability of CO2 hydrate for phytoplankton culture. Specifically, green algae Pseudokirchneriella subcapitata were cultured in COMBO medium that contained dissolved CO2 hydrate, after which its effects were evaluated. The experiment was conducted according to a general bioassay procedure (OECD TG201). CO2 promoted algae growth effectively (about 2-fold relative to the control), and the decrease in pH due to dissolution of the CO2 in water recovered soon because of photosynthesis. Since the CO2 hydrate method can control a CO2 concentration easily and quantitatively, it is expected to be useful in future applications.

  5. Understanding Air-Sea Coupling Processes and Coupled Model Predictions Using GOTEX Measurements and COAMPS/NCOM and Aircraft Measurements for Understanding Air-Sea Coupling and Improving Coupled Model Predictions

    DTIC Science & Technology

    2012-09-30

    part of the Dynamics of the Madden- Julian Oscillation (DYNAMO) and ONR Litterol Littoral Air-Sea Processes (LASP) DRI. The objectives of the GOTEX... McCreary et al.1989). These studies have hypothesized that a fully-coupled model study of the gap outflow would be beneficial. Observations from...REFERENCES McCreary , J. P., H. S. Lee, and D. B. Enfield, 1989: The response of the coastal ocean to strong offshore winds: With

  6. Simulation Studies of Satellite Laser CO2 Mission Concepts

    NASA Technical Reports Server (NTRS)

    Kawa, Stephan Randy; Mao, J.; Abshire, J. B.; Collatz, G. J.; Sun X.; Weaver, C. J.

    2011-01-01

    Results of mission simulation studies are presented for a laser-based atmospheric CO2 sounder. The simulations are based on real-time carbon cycle process modeling and data analysis. The mission concept corresponds to ASCENDS as recommended by the US National Academy of Sciences Decadal Survey. Compared to passive sensors, active (lidar) sensing of CO2 from space has several potentially significant advantages that hold promise to advance CO2 measurement capability in the next decade. Although the precision and accuracy requirements remain at unprecedented levels of stringency, analysis of possible instrument technology indicates that such sensors are more than feasible. Radiative transfer model calculations, an instrument model with representative errors, and a simple retrieval approach complete the cycle from "nature" run to "pseudodata" CO2. Several mission and instrument configuration options are examined, and the sensitivity to key design variables is shown. Examples are also shown of how the resulting pseudo-measurements might be used to address key carbon cycle science questions.

  7. CO2 Accounting and Risk Analysis for CO2 Sequestration at Enhanced Oil Recovery Sites.

    PubMed

    Dai, Zhenxue; Viswanathan, Hari; Middleton, Richard; Pan, Feng; Ampomah, William; Yang, Changbing; Jia, Wei; Xiao, Ting; Lee, Si-Yong; McPherson, Brian; Balch, Robert; Grigg, Reid; White, Mark

    2016-07-19

    Using CO2 in enhanced oil recovery (CO2-EOR) is a promising technology for emissions management because CO2-EOR can dramatically reduce sequestration costs in the absence of emissions policies that include incentives for carbon capture and storage. This study develops a multiscale statistical framework to perform CO2 accounting and risk analysis in an EOR environment at the Farnsworth Unit (FWU), Texas. A set of geostatistical-based Monte Carlo simulations of CO2-oil/gas-water flow and transport in the Morrow formation are conducted for global sensitivity and statistical analysis of the major risk metrics: CO2/water injection/production rates, cumulative net CO2 storage, cumulative oil/gas productions, and CO2 breakthrough time. The median and confidence intervals are estimated for quantifying uncertainty ranges of the risk metrics. A response-surface-based economic model has been derived to calculate the CO2-EOR profitability for the FWU site with a current oil price, which suggests that approximately 31% of the 1000 realizations can be profitable. If government carbon-tax credits are available, or the oil price goes up or CO2 capture and operating expenses reduce, more realizations would be profitable. The results from this study provide valuable insights for understanding CO2 storage potential and the corresponding environmental and economic risks of commercial-scale CO2-sequestration in depleted reservoirs.

  8. CO2 deserts: implications of existing CO2 supply limitations for carbon management.

    PubMed

    Middleton, Richard S; Clarens, Andres F; Liu, Xiaowei; Bielicki, Jeffrey M; Levine, Jonathan S

    2014-10-07

    Efforts to mitigate the impacts of climate change will require deep reductions in anthropogenic CO2 emissions on the scale of gigatonnes per year. CO2 capture and utilization and/or storage technologies are a class of approaches that can substantially reduce CO2 emissions. Even though examples of this approach, such as CO2-enhanced oil recovery, are already being practiced on a scale >0.05 Gt/year, little attention has been focused on the supply of CO2 for these projects. Here, facility-scale data newly collected by the U.S. Environmental Protection Agency was processed to produce the first comprehensive map of CO2 sources from industrial sectors currently supplying CO2 in the United States. Collectively these sources produce 0.16 Gt/year, but the data reveal the presence of large areas without access to CO2 at an industrially relevant scale (>25 kt/year). Even though some facilities with the capability to capture CO2 are not doing so and in some regions pipeline networks are being built to link CO2 sources and sinks, much of the country exists in "CO2 deserts". A life cycle analysis of the sources reveals that the predominant source of CO2, dedicated wells, has the largest carbon footprint further confounding prospects for rational carbon management strategies.

  9. Effects of CO2 leakage on soil bacterial communities from simulated CO2-EOR areas.

    PubMed

    Chen, Fu; Yang, Yongjun; Ma, Yanjun; Hou, Huping; Zhang, Shaoliang; Ma, Jing

    2016-05-18

    CO2-EOR (enhanced oil recovery) has been proposed as a viable option for flooding oil and reducing anthropogenic CO2 contribution to the atmospheric pool. However, the potential risk of CO2 leakage from the process poses a threat to the ecological system. High-throughput sequencing was used to investigate the effects of CO2 emission on the composition and structure of soil bacterial communities. The diversity of bacterial communities notably decreased with increasing CO2 flux. The composition of bacterial communities varied along the CO2 flux, with increasing CO2 flux accompanied by increases in the relative abundance of Bacteroidetes and Firmicutes phyla, but decreases in the relative abundance of Acidobacteria and Chloroflexi phyla. Within the Firmicutes phylum, the genus Lactobacillus increased sharply when the CO2 flux was at its highest point. Alpha and beta diversity analysis revealed that differences in bacterial communities were best explained by CO2 flux. The redundancy analysis (RDA) revealed that differences in bacterial communities were best explained by soil pH values which related to CO2 flux. These results could be useful for evaluating the risk of potential CO2 leakages on the ecosystems associated with CO2-EOR processes.

  10. Air-Sea Fluxes in Terra Nova Bay, Antarctica from In Situ Aircraft Measurements

    NASA Astrophysics Data System (ADS)

    Knuth, S. L.; Cassano, J. J.

    2011-12-01

    In September 2009, the first unmanned aerial vehicles (UAVs) were flown over Terra Nova Bay, Antarctica to collect information regarding air-sea interactions over a wintertime coastal polynya. The UAVs measured wind, temperature, pressure, and relative humidity in flights parallel to the downslope wind flow over the polynya, and in a series of vertical profiles at varying distances from the coast. During three flights on three different days, sufficient measurements were collected to calculate sensible heat, latent heat, and momentum fluxes over varying oceanic surface states, including frazil, pancake, and rafted ice, with background winds greater than 15 ms-1. During the three flights, sensible heat fluxes upwards of 600 Wm-2 were estimated near the coast, with maximum latent heat fluxes near 160 Wm-2 just downwind of the coast. The calculated accelerations due to the momentum flux divergence were on the order of 10-3 ms-2. In addition to the fluxes, changes in the overall momentum budget, including the horizontal pressure gradient force, were also calculated during the three flights. This presentation will summarize the methodology for calculating the fluxes from the UAV data, present the first ever in situ estimates of sensible heat, latent heat, and momentum fluxes and overall momentum budget estimates over Terra Nova Bay, and compare the UAV flux calculations to flux measurements taken during other field campaigns in other regions of the Antarctic, as well as to model estimates over Terra Nova Bay.

  11. Air-sea interaction at the Southern Brazilian Continental Shelf: In situ observations

    NASA Astrophysics Data System (ADS)

    Pezzi, L. P.; Souza, R. B.; Farias, P. C.; Acevedo, O.; Miller, A. J.

    2016-09-01

    The influence of the cross-shelf oceanographic front occurring between the Brazil Current (BC) and the Brazilian Coastal Current (BCC) on the local Marine Atmospheric Boundary Layer (MABL) is investigated here. This front is typical of wintertime in the Southern Brazilian Continental Shelf (SBCS) and this is the first time that its effects are investigated over the above MABL. Here we analyze variability, vertical structure, and stability of MABL as well as heat fluxes at air-sea interface, across five oceanographic transects in the SBCS made during a winter 2012 cruise. Local thermal gradients associated with mixing between distinct water masses, play an essential role on MABL modulation and stability. Although weaker when compared with other frontal regions, the cross-shelf thermal gradients reproduce exactly what is expected for open ocean regions: Stronger (weaker) winds, lower (higher) sea level pressure, and a more unstable (stable) MABL are found over the warm (cold) side of the oceanographic front between the BC (warm) and coastal (cold) waters. Our findings strongly support the coexistence of both known MABL modulation mechanisms: the static and hydrostatic MABL stability. This is the first time that these modulation mechanisms are documented for this region. Turbulent fluxes were found to be markedly dependent on the cross-shelf SST gradients resulting in differences of up to 100 W.m-2 especially in the southernmost region where the gradients were more intense.

  12. Mississippi State University Center for Air Sea Technology FY95 Research Program

    NASA Technical Reports Server (NTRS)

    Yeske, Lanny; Corbin, James H.

    1995-01-01

    The Mississippi State University (MSU) Center for Air Sea Technology (CAST) evolved from the Institute for Naval Oceanography's (INO) Experimental Center for Mesoscale Ocean Prediction (ECMOP) which was started in 1989. MSU CAST subsequently began operation on 1 October 1992 under an Office of Naval Research (ONR) two-year grant which ended on 30 September 1994. In FY95 MSU CAST was successful in obtaining five additional research grants from ONR, as well as several other research contracts from the Naval Oceanographic Office via NASA, the Naval Research Laboratory, the Army Corps of Engineers, and private industry. In the past, MSU CAST technical research and development has produced tools, systems, techniques, and procedures that improve efficiency and overcome deficiency for both the operational and research communities residing with the Department of Defense, private industry, and university ocean modeling community. We continued this effort with the following thrust areas: to develop advanced methodologies and tools for model evaluation, validation and visualization, both oceanographic and atmospheric; to develop a system-level capability for conducting temporally and ; spatially scaled ocean simulations driven by or are responsive to ocean models, and take into consideration coupling to atmospheric models; to continue the existing oceanographic/atmospheric data management task with emphasis on distributed databases in a network environment, with database optimization and standardization, including use of Mosaic and World Wide Web (WWW) access; and to implement a high performance parallel computing technology for CAST ocean models

  13. Air-Sea Methane Flux after the Deepwater Horizon Oil Leak

    NASA Astrophysics Data System (ADS)

    McAdoo, J.; Sweeney, C.; Kiene, R. P.; McGillis, W. R.

    2012-12-01

    One of the key questions associated with the Deepwater Horizon's (DWH) oil leak involves understanding how much of its methane is still entrained in deep waters. Analysis of air-sea fluxes reveals a slight decrease in average aqueous CH4 from 3.3 nM in June to 3.1 and 2.8 nM in August and September, respectively. The flux estimate showed higher methane flux to the atmosphere after the blowout was capped (3.8 μmol m-2 d-1 in August) compared to 0.024 μmol m-2 d-1 during the leak. Almost all observations were within the range of historical levels. The exception was one large peak to the southwest of the wellhead, but its contribution to atmospheric methane is found to be insignificant compared to the total amount of methane released by the leak. This result supports findings that DWH methane remained entrained in the deep waters and consequently is available for biological degradation and threatens to deplete oxygen, adding further stress to an area that already suffers from anoxic-induced dead zones.

  14. Mechanisms controlling the SST air-sea heat flux feedback and its dependence on spatial scale

    NASA Astrophysics Data System (ADS)

    Hausmann, Ute; Czaja, Arnaud; Marshall, John

    2017-02-01

    The turbulent air-sea heat flux feedback (α, in {W m}^{-2} { K}^{-1}) is a major contributor to setting the damping timescale of sea surface temperature (SST) anomalies. In this study we compare the spatial distribution and magnitude of α in the North Atlantic and the Southern Ocean, as estimated from the ERA-Interim reanalysis dataset. The comparison is rationalized in terms of an upper bound on the heat flux feedback, associated with "fast" atmospheric export of temperature and moisture anomalies away from the marine boundary layer, and a lower bound associated with "slow" export. It is found that regions of cold surface waters (≤10 ° C) are best described as approaching the slow export limit. This conclusion is not only valid at the synoptic scale resolved by the reanalysis data, but also on basin scales. In particular, it applies to the heat flux feedback acting as circumpolar SST anomaly scales are approached in the Southern Ocean, with feedbacks of ≤10 {W m}^{-2} { K}^{-1}. In contrast, the magnitude of the heat flux feedback is close to that expected from the fast export limit over the Gulf Stream and its recirculation with values on the order of ≈40 {W m}^{-2} { K}^{-1}. Further analysis suggests that this high value reflects a compensation between a moderate thermodynamic adjustment of the boundary layer, which tends to weaken the heat flux feedback, and an enhancement of the surface winds over warm SST anomalies, which tend to enhance the feedback.

  15. A C-band scatterometer for remote sensing the air-sea interface

    NASA Technical Reports Server (NTRS)

    Mclaughlin, David J.; Mcintosh, Robert E.; Pazmany, Andrew; Hevizi, Laszlo; Boltniew, Eugene

    1991-01-01

    An airborne C-band scatterometer system (C-Scat) has been developed to remotely sense ocean surface winds and improve upon the present understanding of the relationship between normalized radar cross section (NRCS) and ocean surface roughness influences such as wind speed and direction, wave height and slope, and the air-sea temperature difference. The scatterometer utilizes a unique frequency-steered microstrip array antenna that is installed beneath the fuselage of an airplane. The antenna is electronically scanned in elevation, from 20 deg to 50 deg off-nadir, and mechanically spins in azimuth. The system is capable of measuring ocean surface NRCS from altitudes as high as 25,000 ft. The transmitter and receiver operate from 4.98 to 5.7 GHz. System parameters such as transmitter pulse width, pulse repetition frequency, output power level, and receiver bandwidth are programmable. Received signals can be averaged and displayed in real time and are stored on a Winchester disk drive for post-flight analysis. Preliminary flight data that demonstrates the instrument's performance is presented.

  16. Decline of hexachlorocyclohexane in the Arctic atmosphere and reversal of air-sea gas exchange

    NASA Astrophysics Data System (ADS)

    Bidleman, T. F.; Jantunen, L. M.; Falconer, R. L.; Barrie, L. A.; Fellin, P.

    1995-02-01

    Hexachlorocyclohexanes (HCHs) are the most abundant organochlorine pesticides in the arctic atmosphere and ocean surface water. A compilation of measurements made between 1979-93 from stations in the Canadian and Norwegian Arctic and from cruises in the Bering and Chukchi seas indicates that atmospheric concentrations of α-HCH have declined significantly (p < 0.01), with a time for 50% decrease of about 4 y in summer-fall and 6 y in winter-spring. The 1992-93 levels of about 100 pg m-3 are 2-4 fold lower than values in the mid-1980s. The trend in γ-HCH is less pronounced, but a decrease is also suggested from measurements in the Canadian Arctic and the Bering-Chukchi seas. HCHs in ocean surface water have remained relatively constant since the early 1980s. The decline in atmospheric α-HCH has reversed the net direction of air-sea gas exchange to the point where some northern waters are now sources of the pesticide to the atmosphere instead of sinks.

  17. A Unified Air-Sea Visualization System: Survey on Gridding Structures

    NASA Technical Reports Server (NTRS)

    Anand, Harsh; Moorhead, Robert

    1995-01-01

    The goal is to develop a Unified Air-Sea Visualization System (UASVS) to enable the rapid fusion of observational, archival, and model data for verification and analysis. To design and develop UASVS, modelers were polled to determine the gridding structures and visualization systems used, and their needs with respect to visual analysis. A basic UASVS requirement is to allow a modeler to explore multiple data sets within a single environment, or to interpolate multiple datasets onto one unified grid. From this survey, the UASVS should be able to visualize 3D scalar/vector fields; render isosurfaces; visualize arbitrary slices of the 3D data; visualize data defined on spectral element grids with the minimum number of interpolation stages; render contours; produce 3D vector plots and streamlines; provide unified visualization of satellite images, observations and model output overlays; display the visualization on a projection of the users choice; implement functions so the user can derive diagnostic values; animate the data to see the time-evolution; animate ocean and atmosphere at different rates; store the record of cursor movement, smooth the path, and animate a window around the moving path; repeatedly start and stop the visual time-stepping; generate VHS tape animations; work on a variety of workstations; and allow visualization across clusters of workstations and scalable high performance computer systems.

  18. The air-sea interface and surface stress under tropical cyclones.

    PubMed

    Soloviev, Alexander V; Lukas, Roger; Donelan, Mark A; Haus, Brian K; Ginis, Isaac

    2014-06-16

    Tropical cyclone track prediction is steadily improving, while storm intensity prediction has seen little progress in the last quarter century. Important physics are not yet well understood and implemented in tropical cyclone forecast models. Missing and unresolved physics, especially at the air-sea interface, are among the factors limiting storm predictions. In a laboratory experiment and coordinated numerical simulation, conducted in this work, the microstructure of the air-water interface under hurricane force wind resembled Kelvin-Helmholtz shear instability between fluids with a large density difference. Supported by these observations, we bring forth the concept that the resulting two-phase environment suppresses short gravity-capillary waves and alters the aerodynamic properties of the sea surface. The unified wave-form and two-phase parameterization model shows the well-known increase of the drag coefficient (Cd) with wind speed, up to ~30 ms(-1). Around 60 ms(-1), the new parameterization predicts a local peak of Ck/Cd, under constant enthalpy exchange coefficient Ck. This peak may explain rapid intensification of some storms to major tropical cyclones and the previously reported local peak of lifetime maximum intensity (bimodal distribution) in the best-track records. The bimodal distribution of maximum lifetime intensity, however, can also be explained by environmental parameters of tropical cyclones alone.

  19. Engineered yeast for enhanced CO2 mineralization.

    PubMed

    Barbero, Roberto; Carnelli, Lino; Simon, Anna; Kao, Albert; Monforte, Alessandra d'Arminio; Riccò, Moreno; Bianchi, Daniele; Belcher, Angela

    2013-02-01

    In this work, a biologically catalyzed CO2 mineralization process for the capture of CO2 from point sources was designed, constructed at a laboratory scale, and, using standard chemical process scale-up protocols, was modeled and evaluated at an industrial scale. A yeast display system in Saccharomyces cerevisae was used to screen several carbonic anhydrase isoforms and mineralization peptides for their impact on CO2 hydration, CaCO3 mineralization, and particle settling rate. Enhanced rates for each of these steps in the CaCO3 mineralization process were confirmed using quantitative techniques in lab-scale measurements. The effect of these enhanced rates on the CO2 capture cost in an industrial scale CO2 mineralization process using coal fly ash as the CaO source was evaluated. The model predicts a process using bCA2- yeast and fly ash is ~10% more cost effective per ton of CO2 captured than a process with no biological molecules, a savings not realized by wild-type yeast and high-temperature stable recombinant CA2 alone or in combination. The levelized cost of electricity for a power plant using this process was calculated and scenarios in which this process compares favorably to CO2 capture by MEA absorption process are presented.

  20. Engineered yeast for enhanced CO2 mineralization†

    PubMed Central

    Barbero, Roberto; Carnelli, Lino; Simon, Anna; Kao, Albert; Monforte, Alessandra d’Arminio; Riccò, Moreno; Bianchi, Daniele; Belcher, Angela

    2014-01-01

    In this work, a biologically catalyzed CO2 mineralization process for the capture of CO2 from point sources was designed, constructed at a laboratory scale, and, using standard chemical process scale-up protocols, was modeled and evaluated at an industrial scale. A yeast display system in Saccharomyces cerevisae was used to screen several carbonic anhydrase isoforms and mineralization peptides for their impact on CO2 hydration, CaCO3 mineralization, and particle settling rate. Enhanced rates for each of these steps in the CaCO3 mineralization process were confirmed using quantitative techniques in lab-scale measurements. The effect of these enhanced rates on the CO2 capture cost in an industrial scale CO2 mineralization process using coal fly ash as the CaO source was evaluated. The model predicts a process using bCA2- yeast and fly ash is ~10% more cost effective per ton of CO2 captured than a process with no biological molecules, a savings not realized by wild-type yeast and high-temperature stable recombinant CA2 alone or in combination. The levelized cost of electricity for a power plant using this process was calculated and scenarios in which this process compares favorably to CO2 capture by MEA absorption process are presented. PMID:25289021

  1. Elevated CO2 and Soil Nitrogen Cycling

    NASA Astrophysics Data System (ADS)

    Hofmockel, K.; Schlesinger, W.

    2002-12-01

    Although forests can be large terrestrial carbon sinks, soil fertility can limit carbon sequestration in response to increased atmospheric CO2. During five years of CO2 fertilization (ambient + 200ppm) at the Duke Free-Air CO2 Enrichment (FACE) site, net primary production increased significantly by an average of 25% in treatment plots. Total nitrogen in the foliar canopy increased by 16%, requiring an additional 1.3 g N m-2yr-1 to be taken up from soils under elevated CO2. Mechanisms supporting increased nitrogen acquisition have not been identified. Here we report on biological N-fixation rates, using the acetylene reduction assay, in litter and mineral soil during three years of the CO2 enrichment experiment. Lack of a significant CO2 treatment effect on acetylene reduction indicates that carbon is not directly limiting biological N fixation. Nutrient addition experiments using a complete block design with glucose, Fe, Mo and P indicate biological N fixation is co-limited by molybdenum and carbon. These results suggest even if elevated atmospheric CO2 enhances below-ground carbon availability via root exudation, biological nitrogen fixation may not be stimulated due to micronutrient limitations. Assessment of future carbon sequestration by forest stands must consider limitations imposed by site fertility, including micronutrients.

  2. Glacial CO2 Cycles: A Composite Scenario

    NASA Astrophysics Data System (ADS)

    Broecker, W. S.

    2015-12-01

    There are three main contributors to the glacial drawdown of atmospheric CO2 content: starvation of the supply of carbon to the ocean-atmosphere reservoir, excess CO2 storage in the deep sea, and surface-ocean cooling. In this talk, I explore a scenario in which all three play significant roles. Key to this scenario is the assumption that deep ocean storage is related to the extent of nutrient stratification of the deep Atlantic. The stronger this stratification, the larger the storage of respiration CO2. Further, it is my contention that the link between Milankovitch insolation cycles and climate is reorganizations of the ocean's thermohaline circulation leading to changes in the deep ocean's CO2 storage. If this is the case, the deep Atlantic d13C record kept in benthic foraminifera shells tells us that deep ocean CO2 storage follows Northern Hemisphere summer insolation cycles and thus lacks the downward ramp so prominent in the records of sea level, benthic 18O and CO2. Rather, the ramp is created by the damping of planetary CO2 emissions during glacial time intervals. As it is premature to present a specific scenario, I provide an example as to how these three contributors might be combined. As their magnitudes and shapes remain largely unconstrained, the intent of this exercise is to provoke creative thinking.

  3. CO2 mitigation via accelerated limestone weathering

    USGS Publications Warehouse

    Rau, Greg H.; Knauss, Kevin G.; Langer, William H.; Caldeira,

    2004-01-01

    We evaluate accelerated weathering of limestone (AWL: CO2 + CaCO3 + H2O=> Ca2+ + 2HCO3-) as a low-tech, inexpensive, high-capacity, environmentally-friendly CO2 capture and sequestration technology. With access to seawater and limestone being essential to this approach, significant limestone resources are close to most CO2-emitting power plants along the coastal US. Waste fines, representing more than 20% of current US crushed limestone production (>109 tonnes/yr), could be used as an inexpensive source of AWL carbonate. Under such circumstances CO2 mitigation cost could be as low as $3-$4/tonne. More broadly, 10-20% of US point-source CO2 emissions could be treated at $20-$30/tonne CO2. AWL end-solution disposal in the ocean would significantly reduce effects on ocean pH and carbonate chemistry relative to those caused by direct atmospheric or ocean CO2 disposal. Indeed, the increase in ocean Ca2+ and bicarbonate offered by AWL should enhance growth of corals and other calcifying marine organisms.

  4. Geological factors affecting CO2 plume distribution

    USGS Publications Warehouse

    Frailey, S.M.; Leetaru, H.

    2009-01-01

    Understanding the lateral extent of a CO2 plume has important implications with regards to buying/leasing pore volume rights, defining the area of review for an injection permit, determining the extent of an MMV plan, and managing basin-scale sequestration from multiple injection sites. The vertical and lateral distribution of CO2 has implications with regards to estimating CO2 storage volume at a specific site and the pore pressure below the caprock. Geologic and flow characteristics such as effective permeability and porosity, capillary pressure, lateral and vertical permeability anisotropy, geologic structure, and thickness all influence and affect the plume distribution to varying degrees. Depending on the variations in these parameters one may dominate the shape and size of the plume. Additionally, these parameters do not necessarily act independently. A comparison of viscous and gravity forces will determine the degree of vertical and lateral flow. However, this is dependent on formation thickness. For example in a thick zone with injection near the base, the CO2 moves radially from the well but will slow at greater radii and vertical movement will dominate. Generally the CO2 plume will not appreciably move laterally until the caprock or a relatively low permeability interval is contacted by the CO2. Conversely, in a relatively thin zone with the injection interval over nearly the entire zone, near the wellbore the CO2 will be distributed over the entire vertical component and will move laterally much further with minimal vertical movement. Assuming no geologic structure, injecting into a thin zone or into a thick zone immediately under a caprock will result in a larger plume size. With a geologic structure such as an anticline, CO2 plume size may be restricted and injection immediately below the caprock may have less lateral plume growth because the structure will induce downward vertical movement of the CO2 until the outer edge of the plume reaches a spill

  5. Regenerable Sorbent for CO2 Removal

    NASA Technical Reports Server (NTRS)

    Alptekin, Gokhan; Jayaraman, Ambal

    2013-01-01

    A durable, high-capacity regenerable sorbent can remove CO2 from the breathing loop under a Martian atmosphere. The system design allows near-ambient temperature operation, needs only a small temperature swing, and sorbent regeneration takes place at or above 8 torr, eliminating the potential for Martian atmosphere to leak into the regeneration bed and into the breathing loop. The physical adsorbent can be used in a metabolic, heat-driven TSA system to remove CO2 from the breathing loop of the astronaut and reject it to the Martian atmosphere. Two (or more) alternating sorbent beds continuously scrub and reject CO2 from the spacesuit ventilation loop. The sorbent beds are cycled, alternately absorbing CO2 from the vent loop and rejecting the adsorbed material into the environment at a high CO2 partial pressure (above 8 torr). The system does not need to run the adsorber at cryogenic temperatures, and uses a much smaller temperature swing. The sorbent removes CO2 via a weak chemical interaction. The interaction is strong enough to enable CO2 adsorption even at 3 to 7.6 torr. However, because the interaction between the surface adsorption sites and the CO2 is relatively weak, the heat input needed to regenerate the sorbent is much lower than that for chemical absorbents. The sorbent developed in this project could potentially find use in a large commercial market in the removal of CO2 emissions from coal-fired power plants, if regulations are put in place to curb carbon emissions from power plants.

  6. The oceanic sink for anthropogenic CO2.

    PubMed

    Sabine, Christopher L; Feely, Richard A; Gruber, Nicolas; Key, Robert M; Lee, Kitack; Bullister, John L; Wanninkhof, Rik; Wong, C S; Wallace, Douglas W R; Tilbrook, Bronte; Millero, Frank J; Peng, Tsung-Hung; Kozyr, Alexander; Ono, Tsueno; Rios, Aida F

    2004-07-16

    Using inorganic carbon measurements from an international survey effort in the 1990s and a tracer-based separation technique, we estimate a global oceanic anthropogenic carbon dioxide (CO2) sink for the period from 1800 to 1994 of 118 +/- 19 petagrams of carbon. The oceanic sink accounts for approximately 48% of the total fossil-fuel and cement-manufacturing emissions, implying that the terrestrial biosphere was a net source of CO2 to the atmosphere of about 39 +/- 28 petagrams of carbon for this period. The current fraction of total anthropogenic CO2 emissions stored in the ocean appears to be about one-third of the long-term potential.

  7. Natural Analog for Geologic Storage of CO2: CO2 accumulation in China

    NASA Astrophysics Data System (ADS)

    Liu, L.; Xu, T.; Liu, N.; Zhou, B.

    2012-12-01

    Natural accumulations of CO2 are potential analogues of CO2 geological storage that can provide useful information on the behaviour of supercritical CO2 in reservoirs. Natural CO2 accumulations are common across Northeast China, and, although they occur in a wide variety of geological settings, their distribution is principally controlled by the Mesozoic-Cenozoic rift basins and associated Quaternary volcanism. High CO2 concentrations (>60 CO2%) in natural gas reservoirs are usually related to volcanism and magmatism, and possesses mantle-genetic origin. CO2 reservoirs consist of sandstone, volcanic rocks and carbonate rocks with the buried depth from 2000-3000 m. Dawsonite is recognized in almost all of the CO2-bearing basin, which has been proved to share the same carbon source with CO2 in the reservoirs in Songliao basin, Hailaer basin and Donghai basin. Petrographic data show that dawsonite is abundant in feldspar- rich sandstone, volcanic rock fragment-rich sandstones and tuff. In some cases, high percentage of dawsonite cement constitutes a diagenetic seal, which occurs in the reservoir-mudstone caprock and prevents upward leakage of CO2. Besides dawsonite, mantle-genetic CO2 flux leads to the formation of calcite, ankerite and siderite. The statistics of porosity and permeability measured from the dawsonite-bearing sandstone and dawsonite-absent sandstone with the almost same burial depth in Songliao basin show that the mantle-genetic CO2 flux result in lower reservoir quality, suggesting that mineral trapping for CO2 is significant. Chemical analyses of formation water in Songliao basin and Hailaer basin indicate that the concentrations of TDS, HCO3-,CO32-, Mg2+,Ca2+ and Na+ + K+ in dawsonite-bearing sandstone are higher than that in dawsonite-absent sandstone. Distribution of CO2 and dawsonite is constrainted by the regional caprocks in the Songliao basin. The charging time of the mantle-genetic CO2 in China dates from 50 to 25 Ma.

  8. Experimental study of CO2 dissolution a convection phenomenon at high pressure

    NASA Astrophysics Data System (ADS)

    Ben Salem, Imen; Chevalier, Sylvie; Faisal, Titly Farhana; Abderrahmane, Hamid; Sassi, Mohamed

    2016-05-01

    The density driven convection phenomenon has a significant role in enhancing the CO2 geological storage capacity. Deep saline aquifers are targeted for large scale geological sequestration. Once the CO2 is injected in saline aquifer, the supercritical CO2 rises up, forms a thin layer of free phase CO2, and the dissolution and molecular diffusion of the dissolved CO2 in brine begins. The CO2 saturated brine is denser than the original brine leading to gravitational convection of CO2 saturated brine. Convection accelerates the dissolution process and thus improves the safety and the efficiency of the sequestration. Laboratory experiments have been previously performed with experimental set-ups allowing the visualization of the phenomenon (1) eventually combined to the measurements of the dissolved CO2 mass transfer (2) as a function of the permeability of the medium. The visualization of the process was possible as Hele-Shaw cells at atmospheric pressure were used. Pressurized cylindrical vessel containing porous media allows measuring mass transfer of CO2 using the pressure decay concept (3) but visualization of the convection/dissolution was not possible for these setups. In this work, we performed experiments in a pressurized transparent cell similar to a Hele-Shaw cell but with bigger aperture. Permeability was varied by changing the size of the glass beads filling the cell. Bromocrysol green was used as a dye to track the pH change due to the presence of dissolved CO2 (1). The phenomenon is captured by a high resolution camera. We studied the effect of the pressure and of the permeability on the fingering pattern, the onset and the timescale of the phenomenon and the quantitative mass transfer of dissolved CO2. Experiments were validated on numerical simulations performed using STOMP (Subsurface Transport Over Multiple Phases) developed by the PNNL (Pacific Northwest National Laboratory) Hydrology group of the Department of Energy, USA. (1) Kneafsey, T

  9. 40 CFR 98.423 - Calculating CO2 supply.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... = Quarterly CO2 concentration measurement in flow for flow meter u in quarter p (wt. %CO2). Qp,u = Quarterly... (metric tons) through flow meter u. CCO2,p = Quarterly CO2 concentration measurement in flow for flow... delivered by CO2 stream u. CCO2,p,u = Quarterly CO2 concentration measurement of CO2 stream u that...

  10. 40 CFR 98.423 - Calculating CO2 supply.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... = Quarterly CO2 concentration measurement in flow for flow meter u in quarter p (wt. %CO2). Qp,u = Quarterly... (metric tons) through flow meter u. CCO2,p = Quarterly CO2 concentration measurement in flow for flow... delivered by CO2 stream u. CCO2,p,u = Quarterly CO2 concentration measurement of CO2 stream u that...

  11. Radar Remote Sensing of Ice and Sea State and Air-Sea Interaction in the Marginal Ice Zone

    DTIC Science & Technology

    2014-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Radar Remote Sensing of Ice and Sea State and Air-Sea...Interaction in the Marginal Ice Zone Hans C. Graber RSMAS – Department of Ocean Sciences Center for Southeastern Tropical Advanced Remote Sensing...scattering and attenuation process of ocean waves interacting with ice . A nautical X-band radar on a vessel dedicated to science would be used to follow the

  12. The Army’s Role in the Air/Sea Battle Concept: A World War II Pacific Theater Case Study

    DTIC Science & Technology

    2013-12-10

    bases in the Central Pacific Area were small due to land availability. Even so, these atoll airbases served as, “unsinkable...Central Pacific Area, this was difficult since most islands were coral atolls and provided little area for build-up of combat power. Larger islands...THE ARMY’S ROLE IN THE AIR/SEA BATTLE CONCEPT: A WORLD WAR II PACIFIC THEATER

  13. CLOUDS, AEROSOLS, RADIATION AND THE AIR-SEA INTERFACE OF THE SOUTHERN OCEAN: ESTABLISHING DIRECTIONS FOR FUTURE RESEARCH

    SciTech Connect

    Wood, Robert; Bretherton, Chris; McFarquhar, Greg; Protat, Alain; Quinn, Patricia; Siems, Steven; Jakob, Christian; Alexander, Simon; Weller, Bob

    2014-09-29

    A workshop sponsored by the Department of Energy was convened at the University of Washington to discuss the state of knowledge of clouds, aerosols and air-sea interaction over the Southern Ocean and to identify strategies for reducing uncertainties in their representation in global and regional models. The Southern Ocean plays a critical role in the global climate system and is a unique pristine environment, yet other than from satellite, there have been sparse observations of clouds, aerosols, radiation and the air-sea interface in this region. Consequently, much is unknown about atmospheric and oceanographic processes and their linkage in this region. Approximately 60 scientists, including graduate students, postdoctoral fellows and senior researchers working in atmospheric and oceanic sciences at U.S. and foreign universities and government laboratories, attended the Southern Ocean Workshop. It began with a day of scientific talks, partly in plenary and partly in two parallel sessions, discussing the current state of the science for clouds, aerosols and air-sea interaction in the Southern Ocean. After the talks, attendees broke into two working groups; one focused on clouds and meteorology, and one focused on aerosols and their interactions with clouds. This was followed by more plenary discussion to synthesize the two working group discussions and to consider possible plans for organized activities to study clouds, aerosols and the air-sea interface in the Southern Ocean. The agenda and talk slides, including short summaries of the highlights of the parallel session talks developed by the session chars, are available at http://www.atmos.washington.edu/socrates/presentations/SouthernOceanPresentations/.

  14. Modeling of Air-Sea Interaction and Ocean Processes for the Northern Arabian Sea Circulation Autonomous Research Project

    DTIC Science & Technology

    2015-09-30

    and space-time variability in the Northwestern Indian Ocean and Arabian Sea on time scales from days up to several seasonal cycles . OBJECTIVES...determine the mechanisms causing vertical mixing in the Arabian Sea: wind mixing, role of air- sea interaction and surface heat and fresh water ...equatorial region and the East African Coastal current, a source of low-salinity water for the Arabian Sea. APPROACH The fast-flowing Somali

  15. The hysteresis response of soil respiration and soil CO2 concentration to soil temperature

    NASA Astrophysics Data System (ADS)

    Zhang, Q., Sr.; Katul, G. G.; Oren, R.; Daly, E.; Manzoni, S.; Yang, D.

    2015-12-01

    Diurnal hysteresis between soil temperature (Ts) and both CO2 concentration ([CO2]) and soil respiration rate (Rs) were reported across different field experiments. However, the causes of these hysteresis patterns remain a subject of debate, with biotic and abiotic factors both invoked as explanations. To address these issues, a CO2 gas transport model is developed by combining layer-wise mass conservation for subsurface gas-phase CO2, Fickian diffusion for gas transfer, and a CO2 source term that depends on soil temperature, moisture, and photosynthetic rate. Using this model, a hierarchy of numerical experiments were employed to disentangle the causes of the hysteretic [CO2]-Ts and CO2 flux-Ts (i.e., F -Ts) relations. Model results show that gas transport alone can introduce both [CO2]-Ts and F-Ts hysteresis, and also confirm prior findings that heat flow in soils lead to [CO2] and F(z) being out of phase with Ts, thereby providing another reason for the occurrence of both hysteresis. The area (Ahys) of the [CO2]-Ts hysteresis near the surface increases, while the Ahys of the Rs-Ts hysteresis decreases as soils become wetter. Moreover, a time-lagged carbon input from photosynthesis deformed the [CO2]-Ts and Rs-Ts patterns, causing a change in the loop direction from counterclockwise to clockwise with decreasing time lag. An asymmetric 8-shaped pattern emerged as the transition state between the two loop directions. Tracing the pattern and direction of the hysteretic [CO2]-Ts and Rs-Ts relations can provide new ways to fingerprint the effects of photosynthesis stimulation on soil microbial activity and detect the corresponding time lags. Key words: Hysteresis; Photosynthesis; Soil CO2 concentration; Soil respiration; Soil temperature; Soil moisture

  16. Measurements of Ocean surface kinematics and heat transfer

    NASA Astrophysics Data System (ADS)

    Veron, Fabrice; Melville, Ken

    2002-11-01

    The top few meters of the oceanic boundary layer play a critical role in the transfers of momentum, gas, mass and heat between the atmosphere and the ocean. These exchanges must necessarily transfer through the surface, and presumably, the rates at which they do are influence by the dynamics of the surface layer. Heat flux in particular is regulated by the thin surface thermal layer which, at most, is only a few millimeter thick. We are specifically interested in the influence of small coherent structures of the surface turbulence on the heat flux. Using active and passive infrared imaging, we were able to measure the evolution the surface velocity and temperature fields over small areas of a few square meters. Preliminary data show that it is possible to apply cross-correlation techniques (typically used for Particle Image Velocimetry) on the passive infrared images. This yields high-resolution surface velocity fields. Using active marking of the surface with an infrared CO2 laser, we have shown that it is possible to also directly recover the surface velocity, but also, by marking appropriate patterns on the surface we have been able to measure the shear strain, vorticity, and surface divergence. With the penetration depth of infrared radiation at these wavelengths being a few microns, these techniques appear to be extremely promising for measuring ocean surface turbulence confined within the thermal boundary layer. We will discuss the results in the context of air sea heat flux and ocean surface turbulence.

  17. CO2 Sensing and CO2 Regulation of Stomatal Conductance: Advances and Open Questions.

    PubMed

    Engineer, Cawas B; Hashimoto-Sugimoto, Mimi; Negi, Juntaro; Israelsson-Nordström, Maria; Azoulay-Shemer, Tamar; Rappel, Wouter-Jan; Iba, Koh; Schroeder, Julian I

    2016-01-01

    Guard cells form epidermal stomatal gas-exchange valves in plants and regulate the aperture of stomatal pores in response to changes in the carbon dioxide (CO2) concentration ([CO2]) in leaves. Moreover, the development of stomata is repressed by elevated CO2 in diverse plant species. Evidence suggests that plants can sense [CO2] changes via guard cells and via mesophyll tissues in mediating stomatal movements. We review new discoveries and open questions on mechanisms mediating CO2-regulated stomatal movements and CO2 modulation of stomatal development, which together function in the CO2 regulation of stomatal conductance and gas exchange in plants. Research in this area is timely in light of the necessity of selecting and developing crop cultivars that perform better in a shifting climate.

  18. How secure is subsurface CO2 storage? Controls on leakage in natural CO2 reservoirs

    NASA Astrophysics Data System (ADS)

    Miocic, Johannes; Gilfillan, Stuart; McDermott, Christopher; Haszeldine, Stuart

    2014-05-01

    Carbon Capture and Storage (CCS) is the only industrial scale technology available to directly reduce carbon dioxide (CO2) emissions from fossil fuelled power plants and large industrial point sources to the atmosphere. The technology includes the capture of CO2 at the source and transport to subsurface storage sites, such as depleted hydrocarbon reservoirs or saline aquifers, where it is injected and stored for long periods of time. To have an impact on the greenhouse gas emissions it is crucial that there is no or only a very low amount of leakage of CO2 from the storage sites to shallow aquifers or the surface. CO2 occurs naturally in reservoirs in the subsurface and has often been stored for millions of years without any leakage incidents. However, in some cases CO2 migrates from the reservoir to the surface. Both leaking and non-leaking natural CO2 reservoirs offer insights into the long-term behaviour of CO2 in the subsurface and on the mechanisms that lead to either leakage or retention of CO2. Here we present the results of a study on leakage mechanisms of natural CO2 reservoirs worldwide. We compiled a global dataset of 49 well described natural CO2 reservoirs of which six are leaking CO2 to the surface, 40 retain CO2 in the subsurface and for three reservoirs the evidence is inconclusive. Likelihood of leakage of CO2 from a reservoir to the surface is governed by the state of CO2 (supercritical vs. gaseous) and the pressure in the reservoir and the direct overburden. Reservoirs with gaseous CO2 is more prone to leak CO2 than reservoirs with dense supercritical CO2. If the reservoir pressure is close to or higher than the least principal stress leakage is likely to occur while reservoirs with pressures close to hydrostatic pressure and below 1200 m depth do not leak. Additionally, a positive pressure gradient from the reservoir into the caprock averts leakage of CO2 into the caprock. Leakage of CO2 occurs in all cases along a fault zone, indicating that

  19. Study on CO2 global recycling system.

    PubMed

    Takeuchi, M; Sakamoto, Y; Niwa, S

    2001-09-28

    In order to assist in finding ways to mitigate CO2 emission and to slow the depletion of fossil fuels we have established and evaluated a representative system, which consists of three technologies developed in our laboratory. These technologies were in CO2 recovery, hydrogen production and methanol synthesis and in addition we established the necessary supporting systems. Analysis of outline designs of the large scale renewable energy power generation system and this system and energy input for building plant, energy input for running plant has been conducted based on a case using this system for a 1000-MW coal fired power plant, followed by an evaluation of the material balance and energy balance. The results are as follows. Energy efficiency is 34%, the CO2 reduction rate is 41%, the balance ratio of the energy and CO2 of the system is 2.2 and 1.8, respectively, on the assumption that the primary renewable energy is solar thermal power generation, the stationary CO2 emission source is a coal-fired power plant and the generation efficiency of the methanol power plant is 60%. By adopting the system, 3.7 million tons of CO2 can be recovered, approximately 2.7 million tons of methanol can be produced, and 15.4 billion kWh of electricity can be generated per year. Compared to generating all electrical power using only coal, approximately 2.6 million tons of coal per year can be saved and approximately 2.15 million tons of CO2 emission can be reduced. Therefore, it is clearly revealed that this system would be effective to reduce CO2 emissions and to utilize renewable energy.

  20. Bifunctional Catalysts for CO2 Reduction

    DTIC Science & Technology

    2014-09-30

    AFRL-OSR-VA-TR-2014-0243 Bifunctional catalysts for CO2 reduction Theodore Betley HARVARD COLLEGE PRESIDENT & FELLOWS OF Final Report 09/30/2014...Prescribed by ANSI Std. Z39.18 PI: Theodore A. Betley Project: Bifunctional Catalysts for CO2 Reduction Project #: 130214 A. Specific Aims 1... catalyst platforms. Details for the construction of these materials, as they deviate from the salen/salan platforms will be described below. 2. Probe

  1. The Twelve Principles of CO2 CHEMISTRY.

    PubMed

    Poliakoff, Martyn; Leitner, Walter; Streng, Emilia S

    2015-01-01

    This paper introduces a set of 12 Principles, based on the acronym CO2 CHEMISTRY, which are intended to form a set of criteria for assessing the viability of different processes or reactions for using CO2 as a feedstock for making organic chemicals. The principles aim to highlight the synergy of Carbon Dioxide Utilisation (CDU) with the components of green and sustainable chemistry as well as briefly pointing out the connection to the energy sector.

  2. Physical-Biogeochemical Interactions that Alter the Uptake of Atmospheric CO2 in the Barents Sea

    NASA Astrophysics Data System (ADS)

    Signorini, S. R.; Hakkinen, S. M.; McClain, C. R.

    2009-04-01

    The Barents Sea is characterized by significant calcification rates during summer promoted by intense coccolithophore blooms that peak during August. Coccolithophores, among which Emiliania huxleyi (E. huxleyi) is the most abundant and widespread species, are considered to be the most productive calcifying organisms on Earth. They inhabit the surface layer (MLD 20m) in highly stratified waters where light intensity is high. E. huxleyi often forms massive blooms in temperate and sub-polar oceans. Coupling of the coccolithophore organic carbon and carbonate pumps interact to consume (photosynthesis) and produce (calcification) CO2. The so-called Rain Ratio, defined as the ratio of particulate inorganic carbon (PIC) to particulate organic carbon (POC) in exported biogenic matter, determines the relative strength of the two biological carbon pumps and influences the flux of CO2 across the surface ocean - atmosphere interface. Here we use a combination of satellite ocean color algorithms, coupled ice-ocean model products, an SST-dependent pCO2 algorithm, and gas exchange parameterization to describe the seasonal and decadal variability of the air-sea CO2 flux in the Barents Sea. Model-derived SST and SSS (1955-2008) are used in conjunction with the pCO2 algorithm and carbonate chemistry to derive decadal trends of sea-air CO2 flux, pH and calcite saturation state. Phytoplankton and calcite production have strong spatial variability. Nutrient supply, biomass and calcite concentrations are modulated by light and MLD seasonal cycle. The size, intensity, and location of coccolithophore blooms vary from year to year, but the peak bloom is always in June in the Central Basin of the sub-polar North Atlantic (45oW - 10oW, 50oN - 65oN) and August in the Barents Sea. Calcification rates range from 5% to 27% of net primary production. The Barents Sea PIC production is about twice that of the Central Basin. Predicted freshening and warming of polar seas may increase stratification

  3. Coastal ocean CO2-carbonic acid-carbonate sediment system of the Anthropocene

    NASA Astrophysics Data System (ADS)

    Andersson, Andreas J.; MacKenzie, Fred T.; Lerman, Abraham

    2006-03-01

    from the Hawaiian Ocean Time series and the calculated air-sea CO2 exchange agrees well with a recent independent estimate of this flux derived from measurements from diverse coastal ecosystems scaled up to the global coastal ocean area.

  4. CO2-selective, Hybrid Membranes by Silation of Alumina

    SciTech Connect

    Luebke, D.R.; Pennline, H.W.

    2007-09-01

    Hybrid membranes are feasible candidates for the separation of CO2 from gas produced in coal-based power generation since they have the potential to combine the high selectivity of polymer membranes and the high permeability of inorganic membranes. An interesting method for producing hybrid membranes is the silation of an inorganic membrane. In this method, trichloro- or alkoxy-silanes interact with hydroxyl groups on the surface of γ-AlO3 or TiO2, binding organic groups to that surface. By varying the length of these organic groups on the organosilane, it should be possible to tailor the effective pore size of the membrane. Similarly, the addition of “CO2-phillic” groups to the silating agent allows for the careful control of surface affinity and the enhancement of surface diffusion mechanisms. This method of producing hybrid membranes selective to CO2 was first attempted by Hyun [1] who silated TiO2 with phenyltriethoxysilane. Later, Way [2] silated γ-AlO3 with octadecyltrichlorosilane. Both researchers were successful in producing membranes with improved selectivity toward CO2, but permeability was not maintained at a commercially applicable level. XPS data indicated that the silating agent did not penetrate into the membrane pores and separation actually occurred in a thin “polymer-like” surface layer. The present study attempts to overcome the mass transfer problems associated with this technique by producing the desired monolayer coverage of silane, and thus develop a highly-permeable CO2-selective hybrid membrane.

  5. Two-phase convective CO2 dissolution in saline aquifers

    DOE PAGES

    Martinez, Mario J.; Hesse, Marc A.

    2016-01-30

    Geologic carbon storage in deep saline aquifers is a promising technology for reducing anthropogenic emissions into the atmosphere. Dissolution of injected CO2 into resident brines is one of the primary trapping mechanisms generally considered necessary to provide long-term storage security. Given that diffusion of CO2 in brine is woefully slow, convective dissolution, driven by a small increase in brine density with CO2 saturation, is considered to be the primary mechanism of dissolution trapping. Previous studies of convective dissolution have typically only considered the convective process in the single-phase region below the capillary transition zone and have either ignored the overlyingmore » two-phase region where dissolution actually takes place or replaced it with a virtual region with reduced or enhanced constant permeability. Our objective is to improve estimates of the long-term dissolution flux of CO2 into brine by including the capillary transition zone in two-phase model simulations. In the fully two-phase model, there is a capillary transition zone above the brine-saturated region over which the brine saturation decreases with increasing elevation. Our two-phase simulations show that the dissolution flux obtained by assuming a brine-saturated, single-phase porous region with a closed upper boundary is recovered in the limit of vanishing entry pressure and capillary transition zone. For typical finite entry pressures and capillary transition zone, however, convection currents penetrate into the two-phase region. As a result, this removes the mass transfer limitation of the diffusive boundary layer and enhances the convective dissolution flux of CO2 more than 3 times above the rate assuming single-phase conditions.« less

  6. Two-phase convective CO2 dissolution in saline aquifers

    NASA Astrophysics Data System (ADS)

    Martinez, M. J.; Hesse, M. A.

    2016-01-01

    Geologic carbon storage in deep saline aquifers is a promising technology for reducing anthropogenic emissions into the atmosphere. Dissolution of injected CO2 into resident brines is one of the primary trapping mechanisms generally considered necessary to provide long-term storage security. Given that diffusion of CO2 in brine is woefully slow, convective dissolution, driven by a small increase in brine density with CO2 saturation, is considered to be the primary mechanism of dissolution trapping. Previous studies of convective dissolution have typically only considered the convective process in the single-phase region below the capillary transition zone and have either ignored the overlying two-phase region where dissolution actually takes place or replaced it with a virtual region with reduced or enhanced constant permeability. Our objective is to improve estimates of the long-term dissolution flux of CO2 into brine by including the capillary transition zone in two-phase model simulations. In the fully two-phase model, there is a capillary transition zone above the brine-saturated region over which the brine saturation decreases with increasing elevation. Our two-phase simulations show that the dissolution flux obtained by assuming a brine-saturated, single-phase porous region with a closed upper boundary is recovered in the limit of vanishing entry pressure and capillary transition zone. For typical finite entry pressures and capillary transition zone, however, convection currents penetrate into the two-phase region. This removes the mass transfer limitation of the diffusive boundary layer and enhances the convective dissolution flux of CO2 more than 3 times above the rate assuming single-phase conditions.

  7. Modeling and analysis of sabatier CO2 reduction system

    NASA Astrophysics Data System (ADS)

    Jeng, F.; Anderson, M.

    To close the air revitalization system (ARS) of the Environmental Control and Life Support System (ECLSS) of the International Space Station (ISS), a Sabatier CO2 reduction subsystem (CRS) is being integrated into the ISS ARS. An analytical model was implemented in both stand-alone Fortran and Aspen Custom Modeler and was developed to simulate the performance of Sabatier CO2 reduction subsystem. Analyses of the reaction thermodynamics, reaction equilibrium, and kinetics of the Sabatier reaction were conducted. The reactor was divided into three zones: primary reaction, first cooling and second cooling zones. Reactions, heat and mass transfers in each of the reactor zone were modeled. Impacts of day and night cycles of ISS on the Sabatier CRS will be addressed. Model predictions will be compared with test data. Imp acts of Sabatier CRS parameters on water recovery will be discussed.

  8. CO2 Acquisition Membrane (CAM) Project

    NASA Technical Reports Server (NTRS)

    Mason, Larry W.

    2003-01-01

    The CO2 Acquisition Membrane (CAM) project was performed to develop, test, and analyze thin film membrane materials for separation and purification of carbon dioxide (CO2) from mixtures of gases, such as those found in the Martian atmosphere. The membranes developed in this project are targeted toward In Situ Resource Utilization (ISRU) applications, such as In Situ Propellant Production (ISPP) and In Situ Consumables Production (ISCP). These membrane materials may be used in a variety of ISRU systems, for example as the atmospheric inlet filter for an ISPP process to enhance the concentration of CO2 for use as a reactant gas, to passively separate argon and nitrogen trace gases from CO2 for habitat pressurization, to provide a system for removal of CO2 from breathing gases in a closed environment, or within a process stream to selectively separate CO2 from other gaseous components. The membranes identified and developed for CAM were evaluated for use in candidate ISRU processes and other gas separation applications, and will help to lay the foundation for future unmanned sample return and human space missions. CAM is a cooperative project split among three institutions: Lockheed Martin Astronautics (LMA), the Colorado School of Mines (CSM), and Marshall Space Flight Center (MSFC).

  9. CO2 cooling in terrestrial planet thermospheres

    NASA Technical Reports Server (NTRS)

    Bougher, S. W.; Hunten, D. M.; Roble, R. G.

    1994-01-01

    We examine the recent progress in the debate on the CO2-O relaxation rate, its temperature dependence, and its corresponding impact on the thermospheric heat budgets of Venus, Earth, and Mars. This comparative approach provides the broadest range of conditions under which a common CO2-O relaxation rate should provide consistent results. New global mean calculations are presented for the heat budgets of these three planets using large CO2-O relaxation rates that have been inferred recently from Earth CO2 radiance measurements and laboratory studies. Results indicate that available Venus and Mars data constrain the CO2-O relaxation rate to be 2-4 x 10(exp -12)/cu cm/s at 300 K. For Venus, this strong cooling serves as an effective thermostat that gives rise to a small variation of thermospheric temperatures over the solar cycle, just as observed. Conversely, CO2 cooling does not appear to be dominant in the dayside heat budget of the Mars thermosphere over most of the solar cycle. For the Earth, this strong cooling implies that the lower thermosphere does not typically require significant eddy diffusion or heat conduction. However, global-scale dynamics or an additional heating mechanism may be needed to restore calculated temperatures to observed values when relaxation rates exceeding 2 x 10(exp -12)/cu cm/s are employed.

  10. CO2 Efflux from Cleared Mangrove Peat

    PubMed Central

    Lovelock, Catherine E.; Ruess, Roger W.; Feller, Ilka C.

    2011-01-01

    Background CO2 emissions from cleared mangrove areas may be substantial, increasing the costs of continued losses of these ecosystems, particularly in mangroves that have highly organic soils. Methodology/Principal Findings We measured CO2 efflux from mangrove soils that had been cleared for up to 20 years on the islands of Twin Cays, Belize. We also disturbed these cleared peat soils to assess what disturbance of soils after clearing may have on CO2 efflux. CO2 efflux from soils declines from time of clearing from ∼10 600 tonnes km−2 year−1 in the first year to 3000 tonnes km2 year−1 after 20 years since clearing. Disturbing peat leads to short term increases in CO2 efflux (27 umol m−2 s−1), but this had returned to baseline levels within 2 days. Conclusions/Significance Deforesting mangroves that grow on peat soils results in CO2 emissions that are comparable to rates estimated for peat collapse in other tropical ecosystems. Preventing deforestation presents an opportunity for countries to benefit from carbon payments for preservation of threatened carbon stocks. PMID:21738628

  11. Density of aqueous solutions of CO2

    SciTech Connect

    Garcia, Julio E.

    2001-10-10

    In this report, we present a numerical representation for the partial molar volume of CO2 in water and the calculation of the corresponding aqueous solution density. The motivation behind this work is related to the importance of having accurate representations for aqueous phase properties in the numerical simulation of carbon dioxide disposal into aquifers as well as in geothermal applications. According to reported experimental data the density of aqueous solutions of CO2 can be as much as 2-3% higher than pure water density. This density variation might produce an influence on the groundwater flow regime. For instance, in geologic sequestration of CO2, convective transport mixing might occur when, several years after injection of carbon dioxide has stopped, the CO2-rich gas phase is concentrated at the top of the formation, just below an overlaying caprock. In this particular case the heavier CO2 saturated water will flow downward and will be replaced by water with a lesser CO2 content.

  12. The Effect of Excess Electron and hole on CO2 Adsorption and Activation on Rutile (110) surface

    PubMed Central

    Yin, Wen-Jin; Wen, Bo; Bandaru, Sateesh; Krack, Matthias; Lau, MW; Liu, Li-Min

    2016-01-01

    CO2 capture and conversion into useful chemical fuel attracts great attention from many different fields. In the reduction process, excess electron is of key importance as it participates in the reaction, thus it is essential to know whether the excess electrons or holes affect the CO2 conversion. Here, the first-principles calculations were carried out to explore the role of excess electron on adsorption and activation of CO2 on rutile (110) surface. The calculated results demonstrate that CO2 can be activated as CO2 anions or CO2 cation when the system contains excess electrons and holes. The electronic structure of the activated CO2 is greatly changed, and the lowest unoccupied molecular orbital of CO2 can be even lower than the conduction band minimum of TiO2, which greatly facilities the CO2 reduction. Meanwhile, the dissociation process of CO2 undergoes an activated CO2− anion in bend configuration rather than the linear, while the long crossing distance of proton transfer greatly hinders the photocatalytic reduction of CO2 on the rutile (110) surface. These results show the importance of the excess electrons on the CO2 reduction process. PMID:26984417

  13. The Effect of Excess Electron and hole on CO2 Adsorption and Activation on Rutile (110) surface.

    PubMed

    Yin, Wen-Jin; Wen, Bo; Bandaru, Sateesh; Krack, Matthias; Lau, M W; Liu, Li-Min

    2016-03-17

    CO2 capture and conversion into useful chemical fuel attracts great attention from many different fields. In the reduction process, excess electron is of key importance as it participates in the reaction, thus it is essential to know whether the excess electrons or holes affect the CO2 conversion. Here, the first-principles calculations were carried out to explore the role of excess electron on adsorption and activation of CO2 on rutile (110) surface. The calculated results demonstrate that CO2 can be activated as CO2 anions or CO2 cation when the system contains excess electrons and holes. The electronic structure of the activated CO2 is greatly changed, and the lowest unoccupied molecular orbital of CO2 can be even lower than the conduction band minimum of TiO2, which greatly facilities the CO2 reduction. Meanwhile, the dissociation process of CO2 undergoes an activated CO2(-) anion in bend configuration rather than the linear, while the long crossing distance of proton transfer greatly hinders the photocatalytic reduction of CO2 on the rutile (110) surface. These results show the importance of the excess electrons on the CO2 reduction process.

  14. Photodissociation dynamics of IBr(-)(CO(2))(n), n<15.

    PubMed

    Sanford, Todd; Han, Sang-Yun; Thompson, Matthew A; Parson, Robert; Lineberger, W Carl

    2005-02-01

    We report the ionic photoproducts produced following photoexcitation of mass selected IBr(-)(CO(2))(n), n=0-14, cluster ions at 790 and 355 nm. These wavelengths provide single state excitation to two dissociative states, corresponding to the A(') (2)Pi(1/2) and B 2 (2)Sigma(1/2) (+) states of the IBr(-) chromophore. Excitation of these states in IBr(-) leads to production of I(-)+Br and Br(-)+I( *), respectively. Potential energy curves for the six lowest electronic states of IBr(-) are calculated, together with structures for IBr(-)(CO(2))(n), n=1-14. Translational energy release measurements on photodissociated IBr(-) determine the I-Br(-) bond strength to be 1.10+/-0.04 eV; related measurements characterize the A(') (2)Pi(1/2)<--X (2)Sigma(1/2) (+) absorption band. Photodissociation product distributions are measured as a function of cluster size following excitation to the A(') (2)Pi(1/2) and B 2 (2)Sigma(1/2) (+) states. The solvent is shown to drive processes such as spin-orbit relaxation, charge transfer, recombination, and vibrational relaxation on the ground electronic state. Following excitation to the A(') (2)Pi(1/2) electronic state, IBr(-)(CO(2))(n) exhibits size-dependent cage fractions remarkably similar to those observed for I(2) (-)(CO(2))(n). In contrast, excitation to the B 2 (2)Sigma(1/2) (+) state shows extensive trapping in excited states that dominates the recombination behavior for all cluster sizes we investigated. Finally, a pump-probe experiment on IBr(-)(CO(2))(8) determines the time required for recombination on the ground state following excitation to the A(') state. While the photofragmentation experiments establish 100% recombination in the ground electronic state for this and larger IBr(-) cluster ions, the time required for recombination is found to be approximately 5 ns, some three orders of magnitude longer than observed for the analogous I(2) (-) cluster ion. Comparisons are made with similar experiments carried out on I(2

  15. Will atmospheric CO2 concentration continue to increase if anthropogenic CO2 emissions cease?

    NASA Astrophysics Data System (ADS)

    MacDougall, A. H.; Eby, M.; Weaver, A. J.

    2013-12-01

    If anthropogenic CO2 emissions were to suddenly cease, the evolution of the atmospheric CO2 concentration would depend on the magnitude and sign of natural carbon sources and sinks. Experiments using Earth system models indicate that overall carbon sinks would dominate. However, these models have typically neglected the permafrost carbon pool, which has the potential to introduce an additional terrestrial source of carbon to the atmosphere. Here we use the University of Victoria Earth System Climate Model, which has recently been expanded to include permafrost carbon stocks and exchanges with the atmosphere. In a scenario of zeroed CO2 and sulphate aerosol emissions, we assess whether the warming induced by specified constant concentrations of non-CO2 greenhouse gases could slow the CO2 decline following zero emissions, or even reverse this trend and cause CO2 to increase over time. We find that a radiative forcing from non-CO2 gases of approximately 0.6 W m-2 results in a near balance of CO2 emissions from the terrestrial biosphere and uptake of CO2 by the oceans, resulting in near-constant atmospheric CO2 concentrations for at least a century after emissions are eliminated. At higher values of non-CO2 radiative forcing, CO2 concentrations increase over time, regardless of when emissions cease during the 21st century. Given that the present-day radiative forcing from non-CO2 greenhouse gases is about 0.95 W m-2, our results suggest that if we were to eliminate all CO2 and aerosols emissions without also decreasing non-CO2 greenhouse gas emissions, CO2 levels would increase over time, resulting in a small increase in climate warming. The sudden and total cessation of anthropogenic CO2 emissions is an unlikely future scenario. However, such cessation experiments provide a useful method for evaluating the relative strength of the terrestrial and oceanic carbon cycle feedbacks in the presence of forcing from non-CO2 greenhouse gasses.

  16. Global CO2 simulation using GOSAT-based surface CO2 flux estimates

    NASA Astrophysics Data System (ADS)

    Takagi, H.; Oda, T.; Saito, M.; Valsala, V.; Belikov, D.; Saeki, T.; Saito, R.; Morino, I.; Uchino, O.; Yoshida, Y.; Yokota, Y.; Bril, A.; Oshchepkov, S.; Andres, R. J.; Maksyutov, S.

    2012-04-01

    Investigating the distribution and temporal variability of surface CO2 fluxes is an active research topic in the field of contemporary carbon cycle dynamics. The technique central to this effort is atmospheric inverse modeling with which surface CO2 fluxes are estimated by making corrections to a priori flux estimates such that mismatches between model-predicted and observed CO2 concentrations are minimized. Past investigations were carried out by utilizing CO2 measurements collected in global networks of surface-based monitoring sites. Now, datasets of column-averaged CO2 dry air mole fraction (XCO2) retrieved from spectral soundings collected by GOSAT are available for complementing the surface-based CO2 observations. These space-based XCO2 data are expected to enhance the spatiotemporal coverage of the existing surface observation network and thus reduce uncertainty associated with the surface flux estimates. We estimated monthly CO2 fluxes in 64 sub-continental regions from a subset of the surface-based GLOBALVIEW CO2 data and the GOSAT FTS SWIR Level 2 XCO2 retrievals. We further simulated CO2 concentrations in 3-D model space using the surface flux estimates obtained. In this presentation, we report the result of a comparison between the simulated CO2 concentrations and independent surface observations. As part of an effort in inter-comparing GOSAT-based surface CO2 flux estimates, we also look at results yielded with XCO2 data retrieved with the PPDF-DOAS algorithm and those made available by the NASA Atmospheric CO2 Observations from Space team. For this study, we used version 08.1 of the National Institute for Environmental Studies atmospheric transport model, which was driven by the Japan Meteorological Agency's JCDAS wind analysis data. The CO2 forward simulations were performed on 2.5° × 2.5° horizontal grids at 32 vertical levels between the surface and the top of the atmosphere. The a priori flux dataset used was comprised of the sum of four

  17. MP3 - A Meteorology and Physical Properties Package to explore Air:Sea interaction on Titan

    NASA Astrophysics Data System (ADS)

    Lorenz, R. D.

    2012-04-01

    The exchange of mass, heat and momentum at the air:sea interface are profound influences on our environment. Titan presents us with an opportunity to study these processes in a novel physical context. The MP3 instrument, under development for the proposed Discovery mission TiME (Titan Mare Explorer) is an integrated suite of small, simple sensors that combines the a traditional meteorology package with liquid physical properties and depth-sounding. In TiME's 6-Titan-day (96-day) nominal mission, MP3 will have an extended measurement opportunity in one of the most evocative environments in the solar system. The mission and instrument benefit from APL's expertise and experience in marine as well as space systems. The topside meteorology sensors (METH, WIND, PRES, TEMP) will yield the first long-duration in-situ data to constrain Global Circulation Models. The sea sensors (TEMP, TURB, DIEL, SOSO) allow high cadence bulk composition measurements to detect heterogeneities as the TiME capsule drifts across Ligeia, while a depth sounder (SONR) will measure the bottom profile. The combination of these sensors (and vehicle dynamics, ACCL) will characterize air:sea exchange. In addition to surface data, a measurement subset (ACCL, PRES, METH, TEMP) is made during descent to characterize the structure of the polar troposphere and marine boundary layer. A single electronics box inside the vehicle performs supervising and data handling functions and is connected to the sensors on the exterior via a wire and fiber optic harness. ACCL: MEMS accelerometers and angular rate sensors measure the vehicle motion during descent and on the surface, to recover wave amplitude and period and to correct wind measurements for vehicle motion. TEMP: Precision sensors are installed at several locations above and below the 'waterline' to measure air and sea temperatures. Installation of topside sensors at several locations ensures that at least one is on the upwind side of the vehicle. PRES: The

  18. Distribution and air-sea exchange of mercury (Hg) in polluted marine environments

    NASA Astrophysics Data System (ADS)

    Bagnato, E.; Sprovieri, M.; Bitetto, M.; Bonsignore, M.; Calabrese, S.; Di Stefano, V.; Oliveri, E.; Parello, F.; Mazzola, S.

    2012-04-01

    Mercury (Hg) is emitted in the atmosphere by anthropogenic and natural sources, these last accounting for one third of the total emissions. Since the pre-industrial age, the atmospheric deposition of mercury have increased notably, while ocean emissions have doubled owing to the re-emission of anthropogenic mercury. Exchange between the atmosphere and ocean plays an important role in cycling and transport of mercury. We present the preliminary results from a study on the distribution and evasion flux of mercury at the atmosphere/sea interface in the Augusta basin (SE Sicily, southern Italy), a semi-enclosed marine area affected by a high degree of contamination (heavy metals and PHA) due to the oil refineries placed inside its commercial harbor. It seems that the intense industrial activity of the past have lead to an high Hg pollution in the bottom sediments of the basin, whose concentrations are far from the background mercury value found in most of the Sicily Strait sediments. The release of mercury into the harbor seawater and its dispersion by diffusion from sediments to the surface, make the Augusta basin a potential supplier of mercury both to the Mediterranean Sea and the atmosphere. Based on these considerations, mercury concentration and flux at the air-sea interface of the Bay have been estimated using a real-time atomic adsorption spectrometer (LUMEX - RA915+) and an home-made accumulation chamber, respectively. Estimated Total Atmospheric Mercury (TGM) concentrations during the cruise on the bay were in the range of 1-3 ng · m-3, with a mean value of about 1.4 ng · m-3. These data well fit with the background Hgatm concentration values detected on the land (1-2 ng · m-3, this work), and, more in general, with the background atmospheric TGM levels found in the North Hemisphere (1.5-1.7 ng · m-3)a. Besides, our measurements are in the range of those reported for other important polluted marine areas. The mercury evasion flux at the air-sea interface

  19. Sequestering CO2 in the Built Environment

    NASA Astrophysics Data System (ADS)

    Constantz, B. R.

    2009-12-01

    Calera’s Carbonate Mineralization by Aqueous Precipitation (CMAP) technology with beneficial reuse has been called, “game-changing” by Carl Pope, Director of the Sierra Club. Calera offers a solution to the scale of the carbon problem. By capturing carbon into the built environment through carbonate mineralization, Calera provides a sound and cost-effective alternative to Geologic Sequestration and Terrestrial Sequestration. The CMAP technology permanently converts carbon dioxide into a mineral form that can be stored above ground, or used as a building material. The process produces a suite of carbonate-containing minerals of various polymorphic forms. Calera product can be substituted into blends with ordinary Portland cements and used as aggregate to produce concrete with reduced carbon, carbon neutral, or carbon negative footprints. For each ton of product produced, approximately half a ton of carbon dioxide can be sequestered using the Calera process. Coal and natural gas are composed of predominately istopically light carbon, as the carbon in the fuel is plant-derived. Thus, power plant CO2 emissions have relatively low δ13C values.The carbon species throughout the CMAP process are identified through measuring the inorganic carbon content, δ13C values of the dissolved carbonate species, and the product carbonate minerals. Measuring δ13C allows for tracking the flue gas CO2 throughout the capture process. Initial analysis of the capture of propane flue gas (δ13C ˜ -25 ‰) with seawater (δ13C ˜ -10 ‰) and industrial brucite tailings from a retired magnesium oxide plant in Moss Landing, CA (δ13C ˜ -7 ‰ from residual calcite) produced carbonate mineral products with a δ13C value of ˜ -20 ‰. This isotopically light carbon, transformed from flue gas to stable carbonate minerals, can be transferred and tracked through the capture process, and finally to the built environment. CMAP provides an economical solution to global warming by producing

  20. Commitment accounting for CO2 emissions

    NASA Astrophysics Data System (ADS)

    Davis, S. J.; Socolow, R. H.

    2013-12-01

    Long-lived energy infrastructure that burns fossil fuels represents a multi-decade 'commitment' to emit CO2. Today's global power sector, alone, represents hundreds of billions of tons of still unrealized 'committed emissions' of CO2. And every year, substantial new commitments to future emissions are made, as new power plants are built. The socioeconomic inertia of these commitments is a major barrier to climate change mitigation. Here, we quantify these annual commitments by a bottom-up analysis of all power plants commissioned between 1950 and 2011; assigning emission commitments to the year when each generator came on line. We find, assuming 40-year commitments, that the global commitment to future emissions from the world's generators in 2011 (the most recent year in our analysis) was 318 Gt CO2, of which 216 Gt CO2 were commitments from the world's coal-fired generators and 134 Gt CO2 were commitments from China's generators. Annual new global commitments exceeded 15 Gt CO2 per year in every year since 2000. Moreover, between 2005-2010 (the latest year of available emissions data), new global commitments were more than twice as large as actual emissions from all power plants. Country-specific ratios of new committed emissions to actual emissions, averaged over 1990-2010 were 4.1 for China, 2.6 for India, 0.9 for the EU, and 0.6 for the US. We urge that the reporting of annual CO2 emissions, already widely institutionalized, be augmented by 'commitment accounting' which makes these future emissions salient. Annual committed emissions and annual emissions of primary power infrastructure. New committed emissions (light green) have grown from approximately 4 Gt CO2 per year in 1960 to roughly 10 Gt CO2 per year between 1970-1995, and then to more than 15 Gt CO2 per year since 2000. Throughout this period, new committed emissions have exceeded annual emissions (blue curve, source: IEA). Although the commitments made 30-40 years ago have largely been realized (dark

  1. Precursory volcanic CO2 signals from space

    NASA Astrophysics Data System (ADS)

    Schwandner, Florian M.; Carn, Simon A.; Kataoka, Fumie; Kuze, Akihiko; Shiomi, Kei; Goto, Naoki

    2016-04-01

    Identification of earliest signals heralding volcanic unrest benefits from the unambiguous detection of precursors that reflect deviation of magmatic systems from metastable background activity. Ascent and emplacement of new basaltic magma at depth may precede eruptions by weeks to months. Transient localized carbon dioxide (CO2) emissions stemming from exsolution from depressurized magma are expected, and have been observed weeks to months ahead of magmatic surface activity. Detecting such CO2 precursors by continuous ground-based monitoring operations is unfortunately not a widely implemented method yet, save a handful of volcanoes. Detecting CO2 emissions from space offers obvious advantages - however it is technologically challenging, not the least due to the increasing atmospheric burden of CO2, against which a surface emission signal is hard to discern. In a multi-year project, we have investigated the feasibility of space-borne detection of pre-eruptive volcanic CO2 passive degassing signals using observations from the Greenhouse Gas Observing SATellite (GOSAT). Since 2010, we have observed over 40 active volcanoes from space using GOSAT's special target mode. Over 72% of targets experienced at least one eruption over that time period, demonstrating the potential utility of space-borne CO2 observations in non-imaging target-mode (point source monitoring mode). While many eruption precursors don't produce large enough CO2 signals to exceed space-borne detection thresholds of current satellite sensors, some of our observations have nevertheless already shown significant positive anomalies preceding eruptions at basaltic volcanoes. In 2014, NASA launched its first satellite dedicated to atmospheric CO2 observation, the Orbiting Carbon Observatory (OCO-2). Its observation strategy differs from the single-shot GOSAT instrument. At the expense of GOSAT's fast time series capability (3-day repeat cycle, vs. 16 for OCO-2), its 8-footprint continuous swath can slice

  2. Evaluation of CO2 Sorption Capacity of Granite for CO2 Geological Sequestration

    NASA Astrophysics Data System (ADS)

    Fujii, T.; Sato, Y.; Lin, H.; Sasaki, K.; Takahashi, T.; Inomata, H.; Hashida, T.

    2007-03-01

    Anthropogenic effects on climate can be mitigated through various measures. Among them being CO2 sequestration into geological reservoirs including deep saline aquifers, depleted oil/gas reservoirs and coal seams are interested in a powerful means for drastically reducing emissions of CO2. When CO2 would be injected into geological reservoir, it should be necessary to know the potential of CO2 storing into the reservoir. In this study, amount of CO2 sorption of granite was to evaluate experimentally at temperatures 50, 70, 100 and 200°C and pressure up to 20 MPa using a magnetic suspension balance (MSB), which allows to measure under supercritical condition. As a result, we confirmed that the granite have the potential of CO2 sorption. Sorption isotherms obtained from the MSB experiment showed that amount of CO2 sorption increased with the increasing pressure and decreased with the increasing temperature for all experimental conditions. Especially, amount of CO2 sorption at 50°C compared with that at other temperatures (70, 100 and 200°C) increased rapidly in the vicinity of the critical state. In addition, the granite showed a maximum of CO2 sorption into granite could reach up to about 1.0% by weight at 50°C and 14.4MPa. The present results may provide a fundamental knowledge for the development of CO2 geological sequestration technology.

  3. Primary, secondary, and tertiary amines for CO2 capture: designing for mesoporous CO2 adsorbents.

    PubMed

    Ko, Young Gun; Shin, Seung Su; Choi, Ung Su

    2011-09-15

    CO(2) emissions, from fossil-fuel-burning power plants, the breathing, etc., influence the global worming on large scale and the man's work efficiency on small scale. The reversible capture of CO(2) is a prominent feature of CO(2) organic-inorganic hybrid adsorbent to sequester CO(2). Herein, (3-aminopropyl) trimethoxysilane (APTMS), [3-(methylamino)propyl] trimethoxysilane (MAPTMS), and [3-(diethylamino) propyl] trimethoxysilane (DEAPTMS) are immobilized on highly ordered mesoporous silicas (SBA-15) to catch CO(2) as primary, secondary, and tertiary aminosilica adsorbents. X-ray photoelectron spectroscopy was used to analyze the immobilized APTMS, MAPTMS, and DEAPTMS on the SBA-15. We report an interesting discovery that the CO(2) adsorption and desorption on the adsorbent depend on the amine type of the aminosilica adsorbent. The adsorbed CO(2) was easily desorbed from the adsorbent with the low energy consumption in the order of tertiary, secondary, and primary amino-adsorbents while the adsorption amount and the bonding-affinity increased in the reverse order. The effectiveness of amino-functionalized (1(o), 2(o), and 3(o) amines) SBA-15s as a CO(2) capturing agent was investigated in terms of adsorption capacity, adsorption-desorption kinetics, and thermodynamics. This work demonstrates apt amine types to catch CO(2) and regenerate the adsorbent, which may open new avenues to designing "CO(2) basket".

  4. Assessing recent air-sea freshwater flux changes using a surface temperature-salinity space framework

    NASA Astrophysics Data System (ADS)

    Grist, Jeremy P.; Josey, Simon A.; Zika, Jan D.; Evans, Dafydd Gwyn; Skliris, Nikolaos

    2016-12-01

    A novel assessment of recent changes in air-sea freshwater fluxes has been conducted using a surface temperature-salinity framework applied to four atmospheric reanalyses. Viewed in the T-S space of the ocean surface, the complex pattern of the longitude-latitude space mean global Precipitation minus Evaporation (PME) reduces to three distinct regions. The analysis is conducted for the period 1979-2007 for which there is most evidence for a broadening of the (atmospheric) tropical belt. All four of the reanalyses display an increase in strength of the water cycle. The range of increase is between 2% and 30% over the period analyzed, with an average of 14%. Considering the average across the reanalyses, the water cycle changes are dominated by changes in tropical as opposed to mid-high latitude precipitation. The increases in the water cycle strength, are consistent in sign, but larger than in a 1% greenhouse gas run of the HadGEM3 climate model. In the model a shift of the precipitation/evaporation cells to higher temperatures is more evident, due to the much stronger global warming signal. The observed changes in freshwater fluxes appear to be reflected in changes in the T-S distribution of the Global Ocean. Specifically, across the diverse range of atmospheric reanalyses considered here, there was an acceleration of the hydrological cycle during 1979-2007 which led to a broadening of the ocean's salinity distribution. Finally, although the reanalyses indicate that the warm temperature tropical precipitation dominated water cycle change, ocean observations suggest that ocean processes redistributed the freshening to lower ocean temperatures.

  5. Air-Sea Exchange and Atmospheric Cycling of Mercury in South China Sea

    NASA Astrophysics Data System (ADS)

    Tseng, C. M.; Liu, C. S.; Lamborg, C. H.

    2014-12-01

    Limited knowledge exists concerning the role of the low-latitude marginal seas in mercury (Hg) emissions on a global scale, especially tropical-subtropical and monsoon-dominated marginal seas in East Asia. To assess this potential mobilization of Hg through air-sea gas exchange, we have determined the dissolved elemental Hg (DEM) and gaseous elemental Hg (GEM) concentrations in surface seawater and atmosphere, respectively, during seasonal oceanographic cruises to the SouthEast Asian Time-series Study (SEATS) station (18 oN, 116 oE) from 2003 to 2007. The sampling and analysis of GEM and DEM were performed on board ship by using an on-line mercury analyzer (GEMA). Over the SCS, the GEM concentrations are elevated 2-3 times above global background values, with higher enhancements in the winter when the northeast monsoon draws air from China. The impact of long-range transport, as controlled by seasonal monsoons, has on the Hg atmospheric distribution and cycling in the SCS. The DEM concentration varied seasonally, with a high in summer and a low in winter and showed a positive correlation with sea surface temperature (SST). The elevated DEM concentration in summer appears mainly abiologically driven. In winter, the SCS acts as a sink of atmosphere Hg0 as a result of low SST and high wind of the year, enhanced vertical mixing and elevated atmospheric gaseous elemental mercury. Annually, the SCS serves as a source of Hg0 to the atmosphere of 300±50 pmol m-2 d-1 (390±60 kmol Hg y-1, ~2.6% of global emission in ~1% of global ocean area), suggesting high regional Hg pollution impacts from the surrounding Mainland (mostly China).

  6. Atmospheric organochlorine pollutants and air-sea exchange of hexachlorocyclohexane in the Bering and Chukchi Seas

    USGS Publications Warehouse

    Hinckley, D.A.; Bidleman, T.F.; Rice, C.P.

    1991-01-01

    Organochlorine pesticides have been found in Arctic fish, marine mammals, birds, and plankton for some time. The lack of local sources and remoteness of the region imply long-range transport and deposition of contaminants into the Arctic from sources to the south. While on the third Soviet-American Joint Ecological Expedition to the Bering and Chukchi Seas (August 1988), high-volume air samples were taken and analyzed for organochlorine pesticides. Hexachlorocyclohexane (HCH), hexachlorobenzene, polychlorinated camphenes, and chlordane (listed in order of abundance, highest to lowest) were quantified. The air-sea gas exchange of HCH was estimated at 18 stations during the cruise. Average alpha-HCH concentrations in concurrent atmosphere and surface water samples were 250 pg m-3 and 2.4 ng L-1, respectively, and average gamma-HCH concentrations were 68 pg m-3 in the atmosphere and 0.6 ng L-1 in surface water. Calculations based on experimentally derived Henry's law constants showed that the surface water was undersaturated with respect to the atmosphere at most stations (alpha-HCH, average 79% saturation; gamma-HCH, average 28% saturation). The flux for alpha-HCH ranged from -47 ng m-2 day-1 (sea to air) to 122 ng m-2 d-1 (air to sea) and averaged 25 ng m-2 d-1 air to sea. All fluxes of gamma-HCH were from air to sea, ranged from 17 to 54 ng m-2 d-1, and averaged 31 ng m-2 d-1.

  7. Observed air-sea interactions in tropical cyclone Isaac over Loop Current mesoscale eddy features