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Best Methods for Obtaining Absolute Water Velocity Profiles from Gliders with ADCPs
Get PDFAutonomous underwater vehicles (AUVs) like gliders are typically used to obtain vertical cross sections of water properties along transects. Another, less common, application is the use of gliders as virtual moorings. Gliders offer many advantages compared with conventional moorings, but extensive evaluation of gliders as mooring substitutes has not been done. Here, temperature and ocean current velocity data from coincidently deployed gliders-as- moorings and moorings are compared to assess the fidelity of glider-as-mooring data. The glider-as-mooring data were processed in a variety of ways and compared with mooring. During August 2012, two gliders sampled in a box pattern around a conventional mooring in 26 m water depth off of Pt. Sal, California for two and six days, respectively. Two box patterns were used, one 500 m on a side (two and four days) and the other 1 km on a side (two days). Temperature and velocity data from the gliders and moorings are compared using linear regressions and contouring techniques. Linear regressions show good agreement between glider and mooring temperatures (r2 = 0.89, p < 0.001). Significant correlations are also found between ADCP-derived velocities from the gliders and the mooring; along-shore velocities exhibit higher correlation (r2 = 0.70, p < 0.001) compared with cross-shore velocities (r2 = 0.37, p < 0.001). Glider versus glider comparisons are similar to glider versus mooring comparisons in the along-shore (r2 = 0.60, p < 0.001) and cross-shore (r2 = 0.36, p < 0.001) directions. Temperature comparisons between gliders also show good agreement (r2 = 0.93, p < 0.001 )
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Improved Methods for Oceanographic High Frequency Radars
Get PDFHF radars measure coastal ocean surface currents with a spatial and temporal resolution that remain unmatched by other approaches. Because they observe the scientifically and economically important coastal zone, these radars often form an integral part of coastal ocean observing systems. Thus, improvements to the techniques they employ and the data they produce would have far reaching impacts.Several opportunities exist to improve HF radar data. First, idealized antenna pat- terns are widely used despite the fact that the most accurate observations are obtained when the radars use measured antenna patterns. Second, the radars produce maps of surface current velocities without estimates of the measurement uncertainties. Third, advances in signal processing techniques over the last few decades have not been evaluated for use with these radars.To simplify and automate the antenna pattern measurement (APM), a method is presented for obtaining antenna pattern measurements for HF radars from ships of op- portunity. Positions obtained from the Automatic Identification System (AIS) are used to identify signals backscattered from ships in ocean current radar data. The ship sig- nal and ship position data are then combined to determine the APM. Data screening methods are developed and shown to produce APMs with low error when compared with APMs obtained with standard approaches.To produce estimates of uncertainty in the surface current observations, a method toestimate uncertainty in the radar directional measurement [3] is identified and combinedwith previous results to produce an estimate of the uncertainty in the radial component observations produced by individual HF radars. The method is evaluated with radar simulations that incorporate complex ocean current scenarios. These simulations suggest processing modifications that inform the application to observational data. Uncertainty estimates are further evaluated using archive data from two operational HF radars. Results from these radars suggest that the uncertainty estimates can be used for data quality control, and would be suitable for incorporation into numerical models.Finally, an evaluation of alternative signal processing techniques suggests that significant improvements in spatial coverage are possible. Oceanographic HF radars typically employ Multiple Signal Classification (MUSIC) for direction of arrival (DOA) estimation. Signal processing literature suggests that several alternative DOA methods may provide advantages over MUSIC when applied to HF radars, which attempt to resolve complex and dynamic flows given poor signal conditions and constrained antenna designs. Results of radar simulations suggest that the Maximum Likelihood method produces improved spatial coverage at higher, though manageable, computational cost.These results imply improvements in the ocean current maps produced by HF radars in terms of more accurate maps, quantified uncertainty, and improved spatial coverage. Improved observations of near shore dynamics will benefit the many practical applications employing these observations, including plume dispersal studies, oil spill response, and search and rescue
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
akirincich/lera_DPd: Second release with bug fixes for spectra, radials, and patterns
No full text<p>This package is the Public version of the HFR_DP software for processing LERA-type HF radar data sets.</p>
<p>This package contains the master programs to process LERA-type HF Radar system data in Matlab from the decimated time series data (a *.mat file pre-divided into chirps) to radial velocities averaged over an azimuthal window for a particular radar site. This code allows for the use of MKII or MKIII radar systems and direction finding methods including; MUSIC, MLE, and WSF.</p>
<p>See HFR_DP_LERA_SETUP_README.m for setup and package details.</p>
<p>See:</p>
<p>Kirincich, A., B. Emery, L. Washburn, and P. Flament, 2018. Surface Current Mapping Using a Hybrid Direction Finding Approach for Flexible Antenna Arrays, JOAT (submitted).</p>
<p>for details about the radar systems, the processing methodologies, and validation comparisons.</p>
<p>Anthony Kirincich WHOI-PO [email protected]</p>This analysis was supported by NSF grants OCE-1657896 and OCE-1736930 to Kirincich, OCE-1658475 to Emery and Washburn and OCE-1736709 to Flament. Flament is also supported by NOAAs Integrated Ocean Observing System through award NA11NOS0120039
Variations on the Author
Get PDF“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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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