1,720,978 research outputs found
Ground-based remote sensing of wind, temperature and aerosol backscattering in an urban environment during different atmospheric stability conditions
No full textThe diurnal evolution of the urban boundary layer over the central area of Rome was observed by the simultaneous and co-located operation of a Doppler sodar, a microwave radiometer and a dual polarization lidar. The Doppler sodar was configured to provide a wind profile up to about 800 m, and a time-height picture of the thermal structure of the urban boundary layer. A microwave radiometer provided a temperature profile up to 600 m with a height resolution of 50 m. The lidar provided profiles of the aerosol backscattering up to about 7-10 km with 30 m height resolution. The experiment was conducted for several days in the year 1998 during day and night with clear sky and low wind. The aerosol profiles in the urban troposphere appear linked to stability conditions in the lower layers and strong pollution. The presence of aerosols, typically in the afternoon hours at heights up to 2-3 km, can be related to a relatively high mixed layer. Such layer is caused by free convection as indicated by the Richardson number, estimated by the temperature and wind data. Some typical case studies are discussed. (C) 2001 Elsevier Science Ltd. All rights reserved
Estimation of atmospheric water vapor flux profiles in the nocturnal unstable urban boundary layer with Doppler sodar and Raman lidar
No full text
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
A Physical–Statistical Approach to Match Passive Microwave Retrieval of Rainfall to Mediterranean Climatology
No full textA physical-statistical approach to simulate cloud structures and their upward radiation over the Mediterranean is described. It aims to construct a synthetic database of microwave passive observations matching the climatological conditions of this geographical region. The synthetic database is conceived to train a Bayesian maximum a postetioti probability inversion scheme to retrieve precipitating cloud parameters from spaceborne microwave radiometric data. The initial microphysical a priori information on vertical profiles of cloud parameters is derived from a mesoscale cloud-resolving model. In order to complement information from cloud models and to match simulations to the conditions of the area of interest, a new approach is proposed. Climatological constraints over the Mediterranean are derived on a monthly basis from available radiosounding profiles, rain-gauge network measurements, and colocated METEOSAT infrared measurements. In order to introduce the actual surface background in the radiative-transfer simulations, a further constraint is represented by the monthly average and variance maps of surface emissivity derived from Special Sensor Microwave Imager (SSM/I) clear-air observations. A validation of the forward model is carried out by comparing a large set of brightness temperatures measured by the SSM/I with the synthetic cloud radiative database to asses its representativeness and range of variability. The marginal contribution of each constraint source, used in the matching process, is also evaluated. Finally, surface rain rates, retrieved from SSM/I data using the new synthetic database, are compared with colocated rain rates measured by a rain-gauge network along the Tiber River basin in Italy throughout 1995. This comparison is performed both for selected case studies and in a statistical way, discussing the major advantages and limitations of the proposed approach
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe 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
Full text linkWe 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
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