1,720,972 research outputs found
Snow cover prediction in the Italian central Apennines using weather forecast and land surface numerical models
Full text linkPresent-day radiative effect from radiation-absorbing aerosols in snow
Full text linkBlack carbon (BC), brown carbon (BrC), and
soil dust are the most important radiation-absorbing aerosols
(RAAs). When RAAs are deposited on the snowpack, they
lower the snow albedo, causing an increase in the solar radiation
absorption. The climatic impact associated with the
snow darkening induced by RAAs is highly uncertain. The
Intergovernmental Panel on Climate Change (IPCC) Special
Report on the Ocean and Cryosphere in a Changing Climate
(SROCC) attributes low and medium confidence to radiative
forcing (RF) from BrC and dust in snow, respectively. Therefore,
the contribution of anthropogenic sources and carbonaceous
aerosols to RAA RF in snow is not clear. Moreover, the
snow albedo perturbation induced by a single RAA species
depends on the presence of other light-absorbing impurities
contained in the snowpack. In this work, we calculated the
present-day RF of RAAs in snow starting from the deposition
fields from a 5-year simulation with the GEOS-Chem global
chemistry and transport model. RF was estimated taking into
account the presence of BC, BrC, and mineral soil dust in
snow, simultaneously. Modeled BC and black carbon equivalent
(BCE) mixing ratios in snow and the fraction of light absorption
due to non-BC compounds (fnon-BC) were compared
with worldwide observations.We showed that BC, BCE, and
fnon-BC, obtained from deposition and precipitation fluxes,
reproduce the regional variability and order of magnitude
of the observations. Global-average all-sky total RAA-, BC-
, BrC-, and dust-snow RF were 0.068, 0.033, 0.0066, and
0.012Wm2, respectively. At a global scale, non-BC compounds
accounted for 40% of RAA-snow RF, while anthropogenic RAAs contributed to the forcing for 56 %. With regard
to non-BC compounds, the largest impact of BrC has
been found during summer in the Arctic (C0.13Wm2).
In the middle latitudes of Asia, the forcing from dust in
spring accounted for 50% (C0.24Wm2) of the total RAA
RF. Uncertainties in absorbing optical properties, RAA mixing
ratio in snow, snow grain dimension, and snow cover
fraction resulted in an overall uncertainty of 50 %/C61 %,
57 %/C183 %, 63 %/C112 %, and 49 %/C77% in BC-
, BrC-, dust-, and total RAA-snow RF, respectively. Uncertainty
upper bounds of BrC and dust were about 2 and 3 times
larger than the upper bounds associated with BC. Higher BrC
and dust uncertainties were mainly due to the presence of
multiple absorbing impurities in the snow. Our results highlight
that an improvement of the representation of RAAs in
snow is desirable, given the potential high efficacy of this
forcing
On the Use of Original and Bias-Corrected Climate Simulations in Regional-Scale Hydrological Scenarios in the Mediterranean Basin
Full text linkThe response of Mediterranean small catchments hydrology to climate change is still relatively unexplored. Regional Climate Models (RCMs) are an established tool for evaluating the expected climate change impact on hydrology. Due to the relatively low resolution and systematic errors, RCM outputs are routinely and statistically post-processed before being used in impact studies. Nevertheless, these techniques can impact the original simulated trends and then impact model results. In this work, we characterize future changes of a small Apennines (Central Italy) catchment hydrology, according to two radiative forcing scenarios (Representative Concentration Pathways, RCPs, 4.5 and 8.5). We also investigate the impact of a widely used bias correction technique, the empirical Quantile Mapping (QM) on the original Climate Change Signal (CCS), and the subsequent alteration of the original Hydrological Change Signal (HCS). Original and bias-corrected simulations of five RCMs from Euro-CORDEX are used to drive the CETEMPS hydrological model CHyM. HCS is assessed by using monthly mean discharge and a hydrological-stress index. HCS shows a large spatial and seasonal variability where the summer results are affected by the largest decrease of mean discharge (down to −50%). QM produces a small alteration of the original CCS, which generates a generally wetter HCS, especially during the spring season
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
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
Evaluating the Response of Hydrological Stress Indices Using the CHyM Model over a Wide Area in Central Italy
Full text linkCentral Italy is characterized by complex orography. The territorial response to heavy precipitation may activate different processes in terms of hydrogeological hazards. Floods, flash floods, and wet mass movements are the main ground effects triggered by heavy or persistent rainfall. The main aim of this work is to present a unique tool that is based on a distributed hydrological model, able to predict different rainfall-induced phenomena, and essential for the civil protection early warning activity. The Cetemps Hydrological Model is applied to the detection of hydrologically stressed areas over a spatial domain covering the central part of Italy during a weather event that occurred in 2014. The validation of three hydrological stress indices is proposed over a geographical area of approximately 64,500 km2 that includes catchments of varying size and physiography. The indices were used to identify areas subject to floods, flash floods, or landslides. Main results showed very high accuracies (~90%) for all proposed indices, with flood false alarms growing downstream to larger basins, but very close to zero in most cases. The three indices can give complementary information about the predominant phenomenon and are able to distinguish fluvial floods from pluvial floods. Nevertheless, the results were influenced by the presence of artificial reservoirs that regulated flood wave propagation, therefore, indices timing slightly worsen downstream in larger basins
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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