1,721,012 research outputs found
RRS Charles Darwin Cruise 135, 24 Oct-18 Nov 2001. ATSR validation cruise: Seychelles - Durban
Full text linkThis report describes RRS Charles Darwin Cruise 135, an ATSR satellite validation cruise which took place in October-November 2001. The cruise was divided into two legs: Leg 1 primarily focussed on ATSR satellite validation and Leg 2 was planned around the recovery of Netherlands Institute of Sea Research (NIOZ) moorings. Throughout the cruise real-time measurements of the air-sea fluxes of momentum, sensible heat, latent heat and CO2 were made, in addition to the usual mean meteorological parameters. The main aim of Leg 1 (Seychelles to Seychelles) was to achieve as many ATSR satellite overpass validations as possible with the SISTeR radiometer. In addition 5 APEX floats were deployed in support of the ARGO Programme and two XBT equatorial sections were made. During Leg 2 (Seychelles to Durban) the key objective was to recover an array of seven moorings, on a section across the Mozambique Channel roughly at its narrowest part, which had been previously deployed by NIOZ. Further ATSR overpass validations were achieved and two more XBT sections were made
GPS and ship head recording system: installation and operators guide
Full text linkThe system described in this manual was developed in response to a requirement for navigational data on 'Vessels of Opportunity' where there are no data available or where it is not possible to gain access to the data.
The remit for the system is to acquire and record navigational data, with the secondary function to display the data for operational use. The system must by nature of its portability relies on the vessel for only its basic requirements ie stowage and mains power. Independence from ship support means that the system does not require operator intervention, unless so desired, for the
duration of deployment
A new formula for determining the atmospheric longwave flux at the ocean surface at mid-high latitudes
No full text[1] The accuracy of two empirical formulae used in recent climatological studies to estimate the atmospheric longwave flux at the ocean surface from ship meteorological reports has been evaluated using research cruise measurements from the northeast Atlantic. The measurements were obtained with a pyrgeometer and corrected for differential heating of the pyrgeometer dome and shortwave transmission through the dome. The formulae tested were from Clark et al. [1974] and Bignami et al. [1995]; neither was capable of providing consistently reliable estimates of the longwave flux. Clark overestimated the mean measured longwave of 341.1 Wm(-2) by 11.7 Wm(-2), while Bignami underestimated by 12.1 Wm(-2). A new formula is developed that expresses the effects of cloud cover and other parameters on the longwave through an adjustment to the measured air temperature. The air temperature is adjusted by the amount necessary to obtain the effective temperature of a blackbody with a radiative flux equivalent to that from the atmosphere. A simple parameterization of the adjustment in terms of the total cloud amount gives longwave estimates that have an improved mean bias error with respect to the measurements of -1.3 Wm(-2). The new formula is still biased under overcast, low cloud base conditions. However, by including a dependence on dew point depression in the formula, this bias is resolved, and the mean error reduced to 0.2 Wm(- 2). The new formula has been tested using measurements made on two subsequent cruises and found to agree to within 2 Wm(-2) in the mean at middle-high latitude
Development of a reliable microelectrode dissolved oxygen sensor
No full textThis article reports the results of a careful experimental and analytical investigation which led to the development of an accurate and reproducible microelectrode dissolved oxygen sensor. Primarily designed for oceanographic applications but also applicable to environmental and water process monitoring, the sensor measures the diffusion controlled current to a bare Pt microdisc electrode for the reduction of oxygen. A successful reconditioning potential waveform is reported which yields a very stable amperometric response over continuous operation, with a maximum deviation of the limiting current under 1.5% over 24 h. An automated calibration method developed to accurately characterise the electrodes is described. Excellent linearity is obtained for all electrodes tested and in each case, the number of apparent electrons for the reduction of oxygen is reported. As an alternative to calibration, an analytical treatment which accounts for temperature and salinity effects is given to calculate the dissolved oxygen concentration directly from the limiting current. While the analytical approach yields a concentration relative error circa 11% for a 50 ?m diameter Pt disc, the calibration, has lower errors and yields a detection limit down to 0.9 ?M with the same disc. Although this investigation builds on established principles, this article describes, for the first time, the conditions required to obtain accurate and reproducible measurements and provides an estimate of their precision. Preliminary field trials to measure oxygen depth profiles in the ocean have proved very encouraging [R. Prien, R. Pascal, M. Mowlem, G. Denuault, M. Sosna, Development and first results of a new fast response microelectrode DO-sensor, in Oceans 2005—Europe, Vols. 1 and 2, 2005, pp. 744–747]
On estimating the atmospheric longwave flux at the ocean surface from ship meteorological reports.
No full textThe accuracy to which the atmospheric component of the longwave flux at the ocean surface can be estimated by using simple empirical formulae, with information from standard ship meteorological reports as input, has been tested by comparison with radiometric measurements made on cruises in the midlatitude North Atlantic and the Southern Ocean. Over a wide range of atmospheric conditions the best agreement between the estimated and measured downwelling longwave flux is obtained by using the formula of Clark et al. [1974], which has a mean bias error with respect to our combined data set of ?0.7 W/m2. Two other formulae were considered: the Bunker [1976] formula, which is found to overestimate the atmospheric longwave flux at values less than about 350 W/m2, resulting in an overall bias of 9.4 W/m2, and the Bignami et al. [1995] formula, which underestimates the flux over the entire range considered, giving a bias of ?26.5W/m2. The difference in performance of the Clark and Bunker formulae is ascribed to the different parameterizations assumed for the effect of clouds and atmospheric humidity on the longwave flux. It is suggested that the Clark formula be used in future climatological studies at midlatitudes
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
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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