7,658 research outputs found
Application of new parameterizations of gas transfer velocity and their impact on regional and global marine CO2 budgets
No full textOne of the dominant sources of uncertainty in the calculation of air–sea flux of carbon dioxide on a global scale originates from the various parameterizations of the gas transfer velocity, k, that are in use. Whilst it is undisputed that most of these parameterizations have shortcomings and neglect processes which influence air–sea gas exchange and do not scale with wind speed alone, there is no general agreement about their relative accuracy.The most widely used parameterizations are based on non-linear functions of wind speed and, to a lesser extent, on sea surface temperature and salinity. Processes such as surface film damping and whitecapping are known to have an effect on air–sea exchange. More recently published parameterizations use friction velocity, sea surface roughness, and significant wave height. These new parameters can account to some extent for processes such as film damping and whitecapping and could potentially explain the spread of wind-speed based transfer velocities published in the literature.We combine some of the principles of two recently published k parameterizations [Glover, D.M., Frew, N.M., McCue, S.J. and Bock, E.J., 2002. A multiyear time series of global gas transfer velocity from the TOPEX dual frequency, normalized radar backscatter algorithm. In: Donelan, M.A., Drennan, W.M., Saltzman, E.S., and Wanninkhof, R. (Eds.), Gas Transfer at Water Surfaces, Geophys. Monograph 127. AGU, Washington, DC, 325–331; Woolf, D.K., 2005. Parameterization of gas transfer velocities and sea-state dependent wave breaking. Tellus, 57B: 87–94] to calculate k as the sum of a linear function of total mean square slope of the sea surface and a wave breaking parameter. This separates contributions from direct and bubble-mediated gas transfer as suggested by Woolf [Woolf, D.K., 2005. Parameterization of gas transfer velocities and sea-state dependent wave breaking. Tellus, 57B: 87–94] and allows us to quantify contributions from these two processes 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
The dialectic of self and other in Montaigne, Proust and Woolf
Full text linkThis thesis investigates the construction of identity in relation to an other. It considers three
writers who, working at moments when the nature of selfhood was an urgent issue, conduct
profound and original enquiries into the question of self- construction, and seeks both to
reassess their contributions to this debate, and, in bringing their preoccupations and methods
to bear upon each other, to open up new ways of approaching and reading their work.
Considering a range of socio-cultural and religious forms of otherness -- the cannibal, the
witch, the Jew, the aristocrat, the woman, the divine -- it embraces material from a number of
important modem critical fields, and suggests how these topics might be combined to offer a
coherent statement about the enduring issue of s elf- fashioning.
The thesis seeks to map out a trajectory of decreasing investment in external communities,
and an increasing perception of the self as a source and agent in the construction of identity.
Looking in turn at the work of Montaigne, Proust and Woolf, it argues that where the Essais
construct complex orders which appropriate the other to reinforce the identity of the self,
Proust and Woolf increasingly, although gradually, and by no means always successfully,
attempt to negotiate a less precisely- engaged relationship between other and self, and to
assign the other a less constitutive role in the realization and expression of identity. The
thesis also considers more briefly contexts in which this trajectory is reversed. To the extent
that they examine modernist subjectivity, Proust and Woolf articulate an anxiety about the
separation of self and world which leads to an attempted recuperation of the integrated orders
depicted by Montaigne
Gesamtkunstwerk as an aesthetic pre-occupation in the novels of Virginia Woolf.
No full textPhDThis thesis aims to show that Wagner's theories of Gesamtkunstwerk were a
pre-occupation in Woolf's work throughout her career. The introduction
explores Gesamtkunstwerk theory, tracing its development in theories
concerning the combination of art forms, I go on to show how Woolf uses the
Voyage Out to explore what the modern novel can learn from musical arts, while
Jacob's Room adds painting to music as a significant field of interest for
Woolf Mrs Dalloway adds to the complexity of combination, for I will
demonstrate that in this novel a Nietzschean interpretation of Wagner's ideas
found in The Birth of Tragedy is detectable, allowing Woolf to compare the
motivation of more extreme avant-garde groups. The chapter on To the
Lighthouse will consider Woolf's evaluation of her parents' cultural
background and the influence of Roger Fry on her developing aesthetic theory
of combination. I shall argue that understanding of these areas allows Woolf to
begin to experiment with her own form of Gesamtkunstwerk. It is in The
Waves that the connection with Wagner is most obvious. Here, I believe
Woolf shifts the focus of attention from Wagnerian theories of
Gesamtkunstwerk to the Modernists' development of such ideas,
demonstrating her knowledge of Diaghilev's Ballets Russes. Looking closely
at the 1915 Raid Scene in The Years, I intend to show that Woolf's thinking on
the concept of combination is equally radical in this novel which is often
considered to be more conventional. I will go on to suggest that Between the
Acts, widely acknowledged to indicate a crisis in Woolf's confidence in
Modernism, marks a turning point in her thinking about the possibilities of
combining the arts to achieve Gesamtkunstwerk. I will argue that in this piece
Woolf provides us with all the elements used to create unity in the previous
works and yet they are never wholly united. Woolf, however, is not suggesting
that Gesamtkunstwerk is an impossibility, she is rather indicating that the
audience lacks the ability to provide the stage for such a piece to exist
Sensitivity of ferry services to the western isles of Scotland to changes in wave and wind climate
Full text linkThe roughness of the seas is rarely mentioned as a major factor in the economic or social welfare of a region. In this study, the relationship between the ocean wave climate and the economy of the Western Isles of Scotland is examined. This sparsely populated region has a high dependency on marine activities, and ferry services provide vital links between communities. The seas in the region are among the roughest in the world during autumn and winter, however, making maintenance of a reliable ferry service both difficult and expensive. A deterioration in wave and wind climate either in response to natural variability or as a regional response to anthropogenic climate change is possible. Satellite altimetry and gale-frequency data are used to analyze the contemporary response of wave and wind climate to the North Atlantic Oscillation (NAO). The sensitivity of wave climate to the NAO extends to ferry routes that are only partially sheltered and are exposed to ocean waves; thus, the reliability of ferry services is sensitive to NAO. Any deterioration of the wave climate will result in a disproportionately large increase in ferry-service disruption. The impacts associated with an unusually large storm event that affected the region in January 2005 are briefly explored to provide an insight into vulnerability to future storm events
Parametrization of gas transfer velocities and sea-state-dependent wave breaking
No full textBoth experimental estimates and different parametrizations of the transfer velocity of poorly soluble gases exhibit a very broad range of values at a given wind speed. Transfer velocities also appear to depend non-linearly on wind speed, and for high wind speeds this non-linearity is widely attributed to the influence of wave breaking. Both theoretical and experimental studies suggest that wave breaking, and associated whitecapping, is not simply dependent on wind speed but depends also on sea state. New parametrizations of gas transfer velocity based on an existing model of the dependence of transfer velocity on wind stress and whitecapping, supplemented by two sea-state-dependent parametrizations of whitecapping, are developed. These new models predict a diversity of transfer velocities at a given wind speed comparable to the diversity of existing parametrizations. Further, the results suggest that some of the existing parametrizations of transfer velocity reflect in part the wind fetch and sea state typical of the experiments used as a basis of the parametrization. It is suggested that transfer velocities may be estimated much more accurately through satellite retrieval of both wind speed and significant wave height than by wind speed alone
Bubbles and the air‐sea transfer velocity of gases
No full textThe exchange of gases between the atmosphere and the oceans may occur directly through the sea surface and indirectly through the mediation of additional transient reservoirs: the bubbles injected into the upper ocean by breaking waves. These bubbles both will increase the gross rate of exchange between air and sea and will tend to force a supersaturation of the upper ocean. These two effects are made explicit by writing the equation for the net air-sea flux of a gas as F = (K0 + K(b))[C - SP(1 + DELTA)], where K(b) is the contribution of bubbles to the transfer velocity (gross exchange rate) and DELTA denotes the supersaturation effect. Significant supersaturations can be attributed to the small (less-than-or-equal-to 150-mum radius) bubbles, which are commonly advected several metres below the sea surface (Woolf and Thorpe, 1991). The values of K(b) attributable to this deep flux of bubbles are negligible for most gases, but much greater values are predicted by considering the total flux of bubbles through the sea surface. The contribution of bubbles to the transfer velocity, K(b), is approximately proportional to the whitecap coverage. Transfer velocities are a complex function of the diffusivity and solubility of the dissolved gas. This function depends on the distribution of the bubbles. Transfer velocities of relatively soluble gases (and particularly the contribution of small bubbles) are limited by the volume flux of the bubbles, V, through the inequality K(b) less-than-or-equal-to V/beta where beta is the Bunsen solubility of the gas. Values of K(b) can be calculated using measurements of the bubbles in a simulated whitecap (Cipriano and Blanchard, 1981). Large (>150-mum radius) bubbles are the main contributors to the air-sea transfer velocity. Transfer velocities are less for more soluble gases. The global average value of K(b) for carbon dioxide is probably between 2 and 10 cm h-1; the best estimate is 8.5 cm h-1.</p
Calculating long-term global air-sea flux of carbon dioxide using scatterometer, passive microwave, and model reanalysis wind data
No full textGlobal air-sea flux of carbon dioxide (CO2) is calculated from wind data acquired by the satellite scatterometer QuikSCAT, the passive microwave radiometer AMSR-E, and the model re-analysis ERA-40 using four of the most commonly used wind-speed dependent parameterizations of gas transfer velocity. The results are compared to obtain an estimate of that uncertainty in the flux calculations which results solely from the origin of the input wind data. We illustrate the discrepancies between these data sets and quantify the uncertainty in the computed air-sea CO2 flux that arises from data processing such as temporal and spatial averaging using AMSR-E as an example data set. The impact of temporal variability of wind speed is shown to be significantly greater than that of spatial variability. However, simple parameterizations of temporal variability are found to be sensor-specific and cannot be applied in a straightforward way to datasets with lower temporal resolutions from other sensors. We show a simple methodology to correct monthly mean data in such a way that parameterizations of temporal variability derived from QuikSCAT data can be applied to data from AMSR-E and ERA-40. This allows us to produce a global 44-year time series of gas transfer velocity and to present a more coherent estimate of air-sea transfer of carbon dioxide from the three most commonly available types of wind data.<br/
Environmental & architectural phenomenology. Vol. 8, issue 1
No full textVol. 8, No. 1, Winter 1997 (includes “items of interest,” "citations received,” book reviews of Robert Mugerauer's Interpretations on Behalf of Place & two books on sustainable design, and essays by Tammeron Francis & David Woolf)
Waves and climate change in the north-east Atlantic
Full text linkWave height in the North Atlantic has been observed to increase over the last quarter-century, based on monthly-mean data derived from observations. Empirical models have linked a large part of this increase in wave height with the North Atlantic Oscillation. Wave models provide a tool to study impacts of various climate change scenarios and investigate physical explanations of statistical results. In this case we use a wave model of the NE Atlantic. Model tests were carried out, using synthetic wind fields, varying the strength of the prevailing westerly winds and the frequency and intensity of storms, the location of storm tracks and the storm propagation speed. The strength of the westerly winds is most effective at increasing mean and maximum monthly wave height. The frequency, intensity, track and speed of storms have little effect on the mean wave height but intensity, track and speed significantly affect maximum wave height
Siam and Laos, 1767-1827
Full text linkArticle on the history of Thai invasions and rebellions against Vientiane and the Chakri DynastySiam and Laos, 1767-1827
David K. Wyatt
Journal of Southeast Asian History
Vol. 4, No. 2 (Sep., 1963), pp. 13-3
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