1,721,110 research outputs found
Dealing with stress: a book review. (Review of: Wind stress over the ocean, eds: I.S.F.Jones & Y.Toba; Air-sea interaction: laws and mechanisms, by G.T.Csanady)
No full textGas exchange and bubble-induced supersaturation in a wind-wave tank
No full textGas exchange and bubble-induced supersaturation were measured in a wind-wave tank using total gas saturation meters. The water in the tank was subjected to bubbling using a large number of frits at a depth of 0.6 m.A simple linear model of bubble-mediated gas exchange implies that this should force an equilibrium supersaturation of 3%. This is confirmed by experiment, but a small additional steady-state supersaturation is also forced by warming. The total steady-state supersaturation is approached asymptotically.When the bubblers were switched off, the total gas pressure approached a new steady state at much lower supersaturation, at a rate that depended on the state of the wind and waves in the tank. The rates of approach on the various equilibria enabled the gas flux across the surface of the bubbles or across the air–water interface to be calculated.In addition a series of experiments was conducted where the water was subjected to bubbling in the presence of wind or wind and paddle waves: in this case gas invasion from the bubbles was balanced by gas evasion near or at the surface resulting in an equilibrium at <3% and enabling the relative strength of the invasion and evasion to be estimated.Gas concentrations could be measured in a rapid, automated manner using simple apparatus. To derive gas fluxes, corrections for changes in water temperature and fluctuations in air pressure are necessary, and these are quantified. In addition, transient fluctuations in gas concentration at the start of bubbling periods allowed mixing within the tank to be observed.<br/
The influence of the North Atlantic Oscillation on sea level in the Mediterranean and the Black Sea derived from satellite altimetry
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Assessment of the reliability of wave observations from Voluntary Observing Ships: insights from the validation of a global wind wave climatology based on Voluntary Observing Ship data
No full textThis paper describes development and validation of a global climatology of basic wave parameters based on the voluntary observing ship (VOS) data from the Comprehensive Ocean-Atmosphere Data Set collection. Climatology covers the period 1958–1997 and presents heights and periods for the wind sea, swell, and significant wave height (SWH) over the global ocean on 2° × 2° spatial resolution. Significant wave height has been derived from separate sea and swell estimates by taking square root of the sum of squares for the seas and swells propagating approximately in the same direction and assuming SWH to be equal to the higher of the two components in all other cases. Special algorithms of corrections were applied to minimize some biases, inherent in visual wave data. Particularly, we corrected overestimation of small seas, corrected underestimation of periods, and analyzed separation between sea and swell. Validation included estimation of random observational errors, observation of sampling errors, and comparison with the alternative wave data. Estimates of random observational errors show that for the majority of locations, observational uncertainties are within 20% of mean values, which allows us to discuss quantitatively the produced climatology. Biases associated with inadequate sampling were quantified using the data from high-resolution WAM hindcast for the period 1979–1993. The highest sampling biases are observed in the South Ocean, where wave height may be underestimated by 1–1.5 m because of poor sampling, primarily associated with a fair weather bias of ship routing and observation. Comparison to the other VOS-based products shows in general higher SWH in our climatology, especially in the midlatitudes. However, comparison with the altimeter data shows that even for well-sampled regions, high waves are still underestimated in VOS, suggesting a ubiquitous fair weather bias. Further ways of improving VOS-based wave climatologies and possible applications are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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