bluuebunny/crossref_metadata_2025 huggingface dataset:
Behavior of a wave‐driven buoyant surface jet on a coral reef
Authors: Herdman Liv M. M. , Hench James L. , Fringer Oliver , Monismith Stephen G.
Published: March 2017

A wave‐driven surface‐buoyant jet exiting a coral reef was studied in order to quantify the amount of water reentrained over the reef crest. Both moored observations and Lagrangian drifters were used to study the fate of the buoyant jet. To investigate in detail the effects of buoyancy and alongshore flow variations, we developed an idealized numerical model of the system. Consistent with previous work, the ratio of alongshore velocity to jet velocity and the jet internal Froude number were found to be important determinants of the fate of the jet. In the absence of buoyancy, the entrainment of fluid at the reef crest creates a significant amount of retention, keeping 60% of water in the reef system. However, when the jet is lighter than the ambient ocean water, the net effect of buoyancy is to enhance the separation of the jet from shore, leading to a greater export of reef water. Matching observations, our modeling predicts that buoyancy limits retention to 30% of the jet flow for conditions existing on the Moorea reef. Overall, the combination of observations and modeling we present here shows that reef‐ocean temperature gradients can play an important role in reef‐ocean exchanges.
Flow paths and variability of the North Atlantic Current: A comparison of observations and a high‐resolution model
Authors: Breckenfelder Tilia , Rhein Monika , Roessler Achim , Böning Claus W. , Biastoch Arne , Behrens Erik , Mertens Christian
Published: March 2017

The North Atlantic Current (NAC) is subject to variability on multiannual to decadal time scales, influencing the transport of volume, heat, and freshwater from the subtropical to the eastern subpolar North Atlantic (NA). Current observational time series are either too short or too episodic to study the processes involved. Here we compare the observed continuous NAC transport time series at the western flank of the Mid‐Atlantic Ridge (MAR) and repeat hydrographic measurements at the OVIDE line in the eastern Atlantic with the NAC transport and circulation in the high‐resolution (1/20°) ocean model configuration VIKING20 (1960–2008). The modeled baroclinic NAC transport relative to 3400 m (24.5 ± 7.1 Sv) at the MAR is only slightly lower than the observed baroclinic mean of 27.4 ± 4.7 Sv from 1993 to 2008, and extends further north by about 0.5°. In the eastern Atlantic, the western NAC (WNAC) carries the bulk of the transport in the model, while transport estimates based on hydrographic measurements from five repeated sections point to a preference for the eastern NAC (ENAC). The model is able to simulate the main features of the subpolar NA, providing confidence to use the model output to analyze the influence of the North Atlantic Oscillation (NAO). Model based velocity composites reveal an enhanced NAC transport across the MAR of up to 6.7 Sv during positive NAO phases. Most of that signal (5.4 Sv) is added to the ENAC transport, while the transport of the WNAC was independent of the NAO.
Requirement of minimal signal‐to‐noise ratios of ocean color sensors and uncertainties of ocean color products
Authors: Qi Lin , Lee Zhongping , Hu Chuanmin , Wang Menghua
Published: March 2017

Using simulations, error propagation theory, and measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS), we determined the minimal signal‐to‐noise ratio (SNR) required for ocean color measurements and product uncertainties at different spatial and temporal scales. First, based on typical top‐of‐atmosphere (TOA) radiance over the ocean, we evaluate the uncertainties in satellite‐derived Rrs in the visible wavelengths (ΔRrs(vis)) due to sensor noise in both the near‐infrared (NIR) and the visible bands. While the former induces noise in Rrs(vis) through atmospheric correction, the latter has a direct impact on Rrs(vis). Such estimated uncertainties are compared with inherent ΔRrs(vis) uncertainties from in situ measurements and from the operational atmosphere correction algorithm. The comparison leads to a conclusion that once SNR(NIR) is above 600:1, an SNR(vis) better than 400:1 will not make a significant reduction in product uncertainties at pixel level under typical conditions for a solar zenith angle of 45°. Then, such uncertainties are found to decrease significantly in data products of oceanic waters when the 1 km pixels from individual images are binned to lower spatial resolution (e.g., 4 km) or temporal resolution (e.g., monthly). Although these findings do not suggest that passive ocean color sensors should have SNR(vis) around 400:1, they do support the argument for more trade space in higher spatial and/or spectral resolutions once this minimal 400:1 SNR(vis) requirement is met.
Large‐scale anomalies in sea‐surface temperature and air‐sea fluxes during wind relaxation events off the United States West Coast in summer
Authors: Flynn Kayla R. , Fewings Melanie R. , Gotschalk Christopher , Lombardo Kelly
Published: March 2017

In summertime along the U.S. West Coast, the winds exhibit a three‐stage cycle spanning ∼12 days. The prevailing upwelling‐favorable winds weaken (relax) or reverse off the Pacific Northwest, then reintensify, then weaken off central California. We study the sea‐surface temperature (SST) response to these “northern” and “southern” wind relaxations. (1) Satellite data indicate northern wind relaxations result in SST anomalies O(+1°C) extending ∼2000 km offshore. Surface heat flux reanalyses indicate the warm anomaly is mainly from decreased latent cooling. (2) After the winds reintensify, SST becomes anomalously cold along central and southern California. (3) During the southern wind relaxations, the cold SST anomaly persists but the SST warms with time. This warming is not driven by surface heat flux. The latent cooling is reduced, yet unlike during the northern relaxation, this change is canceled by a decrease in solar radiation due to increased cloudiness. In the region south of Point Conception, reduced southward advection of cold water and increased northward advection of warm water by the coastal countercurrent could explain the warming. Reduced Ekman pumping likely contributes to the warming trend during the southern relaxations, and reduced wind‐driven entrainment at the base of the mixed layer likely contributes to the warming during both relaxations. Whether the net surface heat flux is the main driver of SST anomalies during wind relaxation depends on the regional response of clouds. Southern wind relaxations follow episodes of enhanced surface cooling, which may contribute to greater cloudiness during southern than northern wind relaxations.
The role of the Indian Ocean sector for prediction of the coupled Indo‐Pacific system: Impact of atmospheric coupling
Authors: Hackert E. C. , Busalacchi A. J. , Carton J. , Murtugudde R. , Arkin P. , Evans M. N.
Published: March 2017

Indian Ocean (IO) dynamics impact ENSO predictability by influencing wind and precipitation anomalies in the Pacific. To test if the upstream influence of the IO improves ENSO validation statistics, a combination of forced ocean, atmosphere, and coupled models are utilized. In one experiment, the full tropical Indo‐Pacific region atmosphere is forced by observed interannual SST anomalies. In the other, the IO is forced by climatological SST. Differences between these two forced atmospheric model experiments spotlight a much richer wind response pattern in the Pacific than previous studies that used idealized forcing and simple linear atmospheric models. Weak westerlies are found near the equator similar to earlier literature. However, at initialization strong easterlies between 30°S–10°S and 0°N–25°N and equatorial convergence of the meridional winds across the entire Pacific are unique findings from this paper. The large‐scale equatorial divergence west of the dateline and northeasterly‐to‐northwesterly cross‐equatorial flow converging on the equator east of the dateline in the Pacific are generated from interannual IO SST coupling. In addition, off‐equatorial downwelling curl impacts large‐scale oceanic waves (i.e., Rossby waves reflect as western boundary Kelvin waves). After 3 months, these downwelling equatorial Kelvin waves propagate across the Pacific and strengthen the NINO3 SST. Eventually Bjerknes feedbacks take hold in the eastern Pacific which allows this warm anomaly to grow. Coupled forecasts for NINO3 SST anomalies for 1993–2014 demonstrate that including interannual IO forcing significantly improves predictions for 3–9 month lead times.
Radical budget and ozone chemistry during autumn in the atmosphere of an urban site in central China
Authors: Lu Xingcheng , Chen Nan , Wang Yuhang , Cao Wenxiang , Zhu Bo , Yao Teng , Fung Jimmy C. H. , Lau Alexis K. H.
Published: March 2017

The ROx (=OH + HO2 + RO2) budget and O3 production at an urban site in central China (Wuhan) during autumn were simulated and analyzed for the first time using a UW Chemical Model 0‐D box model constrained by in situ observational data. The daytime average OH, HO2, and RO2 concentrations were 2.2 × 106, 1.0 × 108, and 5.2 × 107 molecules cm−3, respectively. The average daytime O3 production rate was 8.8 ppbv h−1, and alkenes were the most important VOC species for O3 formation (contributing 45%) at this site. Our sensitivity test indicated that the atmospheric environment in Wuhan during autumn belongs to the VOC‐limited regime. The daily average HONO concentration at this site during the study period reached 1.1 ppbv and played an important role in the oxidative capacity of the atmosphere. Without the source of excess HONO, the average daytime OH, HO2, RO2, and O3 production rates decreased by 36%, 26%, 27%, and 31% respectively. A correlation between the HONO to NO2 heterogeneous conversion efficiency and PM2.5 × SWR was found at this site; based on this relationship, if the PM2.5 concentration met the World Health Organization air quality standard (25 µg m−3), the O3 production rate in this city would decrease by 19% during late autumn. The burning of agricultural biomass severely affected the air quality in Wuhan during summer and autumn. Agricultural burning was found to account for 18% of the O3 formation during the study period. Our results suggest that VOC control and a ban on agricultural biomass burning should be considered as high‐priority measures for improving the air quality in this region.
Initial electric field changes of lightning flashes in two thunderstorms
Authors: Chapman Ryan , Marshall Thomas , Karunarathne Sumedhe , Stolzenburg Maribeth
Published: March 2017

The beginning of all 75 lightning flashes in two small thunderstorms was investigated using an array of electric field change (E‐change) meters and an array of VHF sensors with the goal of determining if an initial E‐change (IEC) preceded the initial breakdown (IB) pulses in each flash. IECs were found at the beginning of all 62 flashes in Storm 1 and all 13 flashes in Storm 2. Hence, it is concluded that an IEC is a fundamental part of most or all lightning initiations and that an IEC is needed prior to the first IB pulse in a flash. IEC durations averaged 0.23 ms for cloud‐to‐ground (CG) flashes (range 0.08–0.54 ms) and averaged 2.7 ms for normal intracloud (IC) flashes (range 0.04–9.8 ms). IEC point dipole moments averaged 26 C m for CG flashes (range 4–86 C m) and averaged −140 C m for normal IC flashes (range −8 to −650 C m). IEC current moments averaged 120 kA m for CG flashes (range 41–410 kA m) and averaged −91 kA m for normal IC flashes (range −2 to −630 kA m). E‐change data support the suggestion that weak narrow bipolar event type events initiate some lightning flashes, but 41 of the 75 flashes had no detectable initiating pulse > 0.04 V m−1 range normalized to 100 km. Two flashes had two IECs; the second IEC of each flash initiated a new lightning channel that propagated in a new direction and at a higher altitude than the original development after the first IEC.
Comparing Australian heat waves in the CMIP5 models through cluster analysis
Authors: Gibson Peter B. , Perkins‐Kirkpatrick Sarah E. , Alexander Lisa V. , Fischer Erich M.
Published: March 2017

Quantitative projections of climate extremes on local to regional scales are highly valuable for planners and decision makers and necessary for effective local climate change adaptation. However, in contrast to the model robustness of simulated extremes at the global scale, the robustness in simulating past and future extremes often diminishes over finer spatial scales. In this study we analyze heat waves simulated by state‐of‐the‐art global climate models over the Australian region. For the first time we present results explicitly detailing the model spread in simulated heat wave trends and climatology for this region for the recent past (1958–2005). As expected, large intermodel spread is observed at the local to regional scale for both heat wave trends and climatology. By analyzing multiple initial condition runs from individual models, we show that model internal variability strongly influences the spatial patterns of heat wave trends, while intermodel differences in heat wave climatology appear more influenced by model uncertainty. From a model evaluation perspective, cluster analysis is shown to be useful in characterizing robust spatial features of heat waves simulated by the models. In contrast to the multimodel mean, where uncorrelated spatial features tend to be averaged out, cluster composites preserve these features. Since previous examinations have tended to focus on the multimodel mean the extent of model spread may have been overlooked. Further examination of the processes that lead to model differences and biases is needed.
Relationships between giant sea salt particles and clouds inferred from aircraft physicochemical data
Authors: Dadashazar Hossein , Wang Zhen , Crosbie Ewan , Brunke Michael , Zeng Xubin , Jonsson Haflidi , Woods Roy K. , Flagan Richard C. , Seinfeld John H. , Sorooshian Armin
Published: March 2017

This study uses airborne data from multiple field campaigns off the California coast to determine the extent to which a size distribution parameter and a cloud water chemical measurement can capture the effect of giant cloud condensation nuclei (GCCN), specifically sea salt, on marine stratocumulus cloud properties. The two GCCN proxy variables, near‐surface particle number concentration for diameters >5 µm and cloud water chloride concentration, are significantly correlated (95% confidence) with each other, and both exhibit expected relationships with other parameters (e.g., surface wind) that typically coincide with sea salt emissions. Factors influencing the relationship between these two GCCN proxy measurements include precipitation rate (R) and the standard deviation of the subcloud vertical velocity owing likely to scavenging effects and improved mixing/transport of sea salt to cloud base, respectively. When comparing 12 pairs of high and low chloride cloud cases (at fixed liquid water path and cloud drop number concentration), the average drop spectra for high chloride cases exhibit enhanced drop number at diameters exceeding 20 µm, especially above 30 µm. In addition, high chloride cases coincide with enhanced mean columnar R and negative values of precipitation susceptibility. The difference in drop effective radius between high and low chloride conditions decreases with height in cloud, suggesting that some GCCN‐produced raindrops precipitate before reaching cloud tops. The sign of cloud responses (i.e., R) to perturbations in giant sea salt particle concentration, as evaluated from Modern Era Retrospective Analysis for Research and Applications version 2 reanalysis data, is consistent with the aircraft data.
Analysis of the lightning‐attractive radius for wind turbines considering the developing process of positive attachment leader
Authors: Yang Ning , Zhang Qilin , Hou Wenhao , Wen Ying
Published: March 2017

In this paper, we have presented the upward leader propagation model, considering the transition of stream leader process by the finite element method and analyzing the inception and subsequent physical processes of upward leader and the attractive radius for large wind turbines. For validating our model, the comparison of simulated results with the optically high‐speed video observation shows that the model can predict an accepted result of upward leader from a 163 m tall tower, the simulated upward leader velocity and length before final jump are 2.3 × 105 m/s and 187.67 m presented by Warner (2010), which are very similar to the observed results of 2.8 × 105 m/s and 184 m, respectively. At the same time, we find that the assumed constant speed ratio of downward/upward leader is improper and cannot accurately predict the attractive radius by lightning strike. Also, the simulated results are compared with the widely used EGM (electro geometric model), and it is found that the EGM has an obvious underestimation of attractive radius more than 50%.
Sources and formation processes of water‐soluble dicarboxylic acids, ω‐oxocarboxylic acids, α‐dicarbonyls, and major ions in summer aerosols from eastern central India
Authors: Deshmukh Dhananjay K. , Kawamura Kimitaka , Deb Manas K. , Boreddy Suresh K. R.
Published: March 2017

The sources and formation processes of dicarboxylic acids are still under investigation. Size‐segregated aerosol (nine‐size) samples collected in the urban site (Raipur: 21.2°N and 82.3°E) in eastern central India during summer of 2013 were measured for water‐soluble diacids (C2‐C12), ω‐oxoacids (ωC2‐ωC9), α‐dicarbonyls (C2‐C3), and inorganic ions to better understand their sources and formation processes. Diacids showed the predominance of oxalic acid (C2), whereas ω‐oxoacids showed the predominance of glyoxylic acid (ωC2), and glyoxal (Gly) was a major α‐dicarbonyl in all the sizes. Diacids, ω‐oxoacids, and α‐dicarbonyls as well as
,
, and
were enriched in coarse mode, where Ca2+ peaked, suggesting that they are preferentially produced in coarse mode via adsorption as well as heterogeneous and aqueous‐phase oxidation reaction of precursors on the surface of water‐soluble mineral dust particles having more alkaline species. Strong correlations of diacids and related compounds with
(r = 0.66–0.91) and aerosol water content (AWC) (r = 0.63–0.93) further suggest the importance of heterogeneous and aqueous‐phase production in coarse mode. We found strong correlations of C2/(C2‐C12), C2/ωC2, and C2/Gly ratios with AWC in coarse mode (r = 0.83, 0.86, and 0.85, respectively), indicating that enhanced AWC is favorable for the production of C2 diacid through aqueous‐phase oxidation of its higher homologous diacids, ωC2, and Gly. These results demonstrates unique reactivity of water‐soluble mineral dust particles for the enhanced production of diacids and related compounds in aqueous‐phase, having implications on the aerosol‐cloud interaction, solubility, and hygroscopicity of a dominant fraction of water‐soluble organic aerosol mass.
Improved modeling of snow and glacier melting by a progressive two‐stage calibration strategy with GRACE and multisource data: How snow and glacier meltwater contributes to the runoff of the Upper Brahmaputra River basin?
Authors: Chen Xi , Long Di , Hong Yang , Zeng Chao , Yan Denghua
Published: March 2017

Snow and glacier melting and accumulation are important processes of the hydrological cycle in the cryosphere, e.g., high‐mountain areas. Glaciers and snow cover respond to climate change notably over the Tibetan Plateau (TP) as the Earth's Third Pole where complex topography and lack of ground‐based observations result in knowledge gaps in hydrological processes and large uncertainties in model output. This study develops a snow and glacier melt model for a distributed hydrological model (Coupled Routing and Excess Storage model, CREST) using the Upper Brahmaputra River (UBR) basin in the TP as a case study. Satellite and ground‐based precipitation and land surface temperature are jointly used as model forcing. A progressive two‐stage calibration strategy is developed to derive model parameters, i.e., (1) snow melting processes (stage I) and (2) glacier melting and runoff generation and routing using multisource data (stage II). Stage‐I calibration is performed using the MODIS snow cover area (SCA) product and a blending snow water equivalent (SWE) product combined with partial in situ measurements. Stage‐II calibration is based on Gravity Recovery and Climate Experiment (GRACE) satellite‐derived total water storage (TWS) changes and streamflow observed at a gauging station of the lower reach of the UBR. Results indicate that the developed two‐stage calibration method provides more reliable streamflow, snow (both SCA and SWE), and TWS change simulations against corresponding observations than commonly used methods based on streamflow and/or SCA performance. The simulated TWS time series shows high consistency with GRACE counterparts for the study period 2003–2014, and overestimated melting rates and contributions of glacier meltwater to runoff in previous studies are improved to some degree by the developed model and calibration strategy. Snow and glacier runoff contributed 10.6% and 9.9% to the total runoff, and the depletion rate of glacier mass was ∼ −10 mm/a (∼ −2.4 Gt/a, Gt/a is gigaton (km3 of water) per year) over the UBR basin during the study period. This study is valuable in examining the impacts of climate change on hydrological processes of cryospheric regions and providing an improved approach for simulating more reliable hydrological variables over the UBR basin and potentially similar regions globally.
Quantifying spatial groundwater dependence in peatlands through a distributed isotope mass balance approach
Authors: Isokangas Elina , Rossi Pekka M. , Ronkanen Anna‐Kaisa , Marttila Hannu , Rozanski Kazimierz , Kløve Bjørn
Published: March 2017

The unique biodiversity and plant composition of peatlands rely on a mix of different water sources: precipitation, runoff, and groundwater (GW). Methods used to delineate areas of ecosystem groundwater dependence, such as vegetation mapping and solute tracer studies, are indirect and lack the potential to assess temporal changes in hydrology, information needed in GW management. This paper outlines a new methodology for mapping groundwater‐dependent areas (GDAs) in peatlands using a 2H and 18O isotope mass balance method. The approach reconstructs the initial isotopic composition of the peat pore water in the uppermost peat layer before its modification by evaporation. It was assumed that pore water in this layer subject to evaporation is a two‐component mixture consisting of GW and precipitation input from the month preceding the sampling period. A Bayesian Monte Carlo isotope mixing model was applied to calculate the proportions of GW and rainwater in the sampled pore water and to assess uncertainties. The approach revealed large spatial variability in the contribution of GW to the pore water present in the top layer of peatland, covering the range from approximately 0 to 100%. Results show that the current GW protection zones determined by Finnish legislation do not cover the GDAs in peatlands and highlight a need for better classification of groundwater‐dependent ecosystems and conceptualization of aquifer‐ecosystem interactions. Our approach offers an efficient tool for mapping GDAs and quantifying the contribution of GW to peatland pore water. However, more studies are needed to test the method for different peatland types.
Quantifying local rainfall dynamics and uncertain boundary conditions into a nested regional‐local flood modeling system
Authors: Bermúdez María , Neal Jeffrey C. , Bates Paul D. , Coxon Gemma , Freer Jim E. , Cea Luis , Puertas Jeronimo
Published: March 2017

Inflow discharge and outflow stage estimates for hydraulic flood models are generally derived from river gauge data. Uncertainties in the measured inflow data and the neglect of rainfall‐runoff contributions to the modeled domain downstream of the gauging locations can have a significant impact on these estimated “whole reach” inflows and consequently on flood predictions. In this study, a method to incorporate rating curve uncertainty and local rainfall‐runoff dynamics into the predictions of a reach‐scale flood model is proposed. The methodology is applied to the July 2007 floods of the River Severn in UK. Discharge uncertainty bounds are generated applying a nonparametric local weighted regression approach to stage‐discharge measurements for two gauging stations. Measured rainfall downstream from these locations is used as input to a series of subcatchment regional hydrological model to quantify additional local inflows along the main channel. A regional simplified‐physics hydraulic model is then applied to combine these contributions and generate an ensemble of discharge and water elevation time series at the boundaries of a local‐scale high complexity hydraulic model. Finally, the effect of these rainfall dynamics and uncertain boundary conditions are evaluated on the local‐scale model. Accurate prediction of the flood peak was obtained with the proposed method, which was only possible by resolving the additional complexity of the extreme rainfall contributions over the modeled area. The findings highlight the importance of estimating boundary condition uncertainty and local rainfall contributions for accurate prediction of river flows and inundation at regional scales.
Observed basin‐wide propagation of Mediterranean water in the Black Sea
Authors: Falina Anastasia , Sarafanov Artem , Özsoy Emin , Utku Turunçoğlu Ufuk
Published: March 2017

Mediterranean water entering the Black Sea through the Bosphorus Strait forms middepth intrusions that contribute to the salt, heat, and volume balances of the sea, ventilate its water column at intermediate depths and restrain the upward flux of hydrogen sulfide from deeper layers. Despite the importance for the Black Sea environment, the circulation of Mediterranean‐origin water in the basin is fundamentally underexplored. Here we use hydrographic data collected from ships and Argo profiling floats to identify pathways of the Mediterranean intrusions in the general circulation system of the sea. While earlier the intrusions were observed primarily near the Bosphorus Strait, we present an evidence for their intermittent extensive propagation throughout the basin. We find that the main conduit for the intrusions is the southern limb of the Rim Current that carries the intruded water from the Bosphorus Strait eastward. A part of this eastward flow recirculates cyclonically into the interior of the sea, where traces of the intrusions gradually disappear because of mixing. We put forward the hypothesis that the formation of the most prominent intrusions is associated with strong cyclonic storms over the Bosphorus Strait, which lead to abnormally large influx of Mediterranean water.
Media Use: Former
E
astern
E
uropean
S
tates
Authors: Stępińska Agnieszka
Published: March 2017

In all the postcommunist Central and Eastern European (CEE) countries, the contemporary media systems are defined by a heritage of decades of communist rule and the influence of market mechanisms introduced after 1990. While during the communist time all media were state‐controlled, in the first decade of the 1990s the ownership structure of the both print and electronic media was radically transformed. The media's role in society was also reconceptualized according to democratic norms. Yet, the historical heritage of the communist regime still serves as a reference point in much of the political, economic, and ethical debates centered on media use and media effects in the CEE countries. Contemporary media use in all the CEE countries can be characterized by an increasing importance of electronic media. This has meant not only a rapid increase in Internet usage but also a dramatic growth in TV watching since the 1990s.
Connecting Media Use to Media Effects
Authors: Scherer Helmut
Published: March 2017

This entry discusses the connection between media usage and media effects on the basis of a thesis, an antithesis, and a synthesis. Thesis: Media use is a precondition of media effects. Antithesis: Media effects are preconditions of media use. Synthesis: Media use and media effects are two sides of the same coin. Media usage and media effects are hardly distinguishable and interwoven. We may regard these processes from either a use or an effects perspective. The chosen perspective depends on our research interests. If we want to emphasize the user's independence from the medium, we speak of media use. If we want to know about the role and significance of media in our society, we use the perspective of media research. It is only possible to look at one side of the coin, although the other side still remains. Further, a coin with only one side is difficult to imagine.
Agenda‐Setting: History and Research Tradition
Authors: Wanta Wayne , Alkazemi Mariam F.
Published: March 2017

The agenda‐setting function of the mass media was first established in the 1970s. Since then, research on agenda‐setting has expanded to include six areas of research. The first category is the original hypothesis, which examines the cognitive effects of news on consumers. The second category, sources of the media agenda, concerns how competing actors in public debate affect public opinion and includes agenda‐building research. The third category, the policy agenda, deals with the effect of news media on policy. The fourth category is contingent conditions, which explains circumstances that may affect the agenda‐setting process. The fifth category is the second level, which shows that there is an affective component to the agenda‐setting process. The sixth category investigates the function of the agenda‐setting process in social media and the Internet. More recently, research has examined visual agenda‐setting and the third level of the agenda‐setting effect.
Third‐Person Effect: Perceptual and Behavioral Component
Authors: Andsager Julie L.
Published: March 2017

The third‐person effect model posits that individuals believe themselves to be unaffected by socially undesirable media messages but that they perceive that other people are negatively influenced. This discrepancy is known as the third‐person effect's perceptual component. Because others may be adversely affected, individuals may act to restrict socially undesirable messages. This action comprises the behavioral component. In this entry, assumptions, key concepts, and research involving each component are considered.
Multistep Flow of Communication: Opinion Leadership and Personality Strength
Authors: Jerabek Hynek
Published: March 2017

The idea of measuring opinion leadership came from Paul Lazarsfeld in the “Erie County Study” in 1940. The two‐step flow of communication hypothesis was also first formulated in this study. Opinion leaders and opinion followers were then studied in the “Decatur Study” and the results were published by Katz and Lazarsfeld in
Personal Influence
(1955). Katz, Menzel, Coleman, and others then examined the “diffusion of ideas” in the “Drug Study.” Merton defined two types of “influentials” in the “Rovere Study”: “locals” and “influentials.” Departing from the dichotomous measure of opinion leadership in the Erie County and subsequent studies, in the 1980s Noelle‐Neumann developed the PS‐Scale (Personality Strength Scale) for the continuous measurement of opinion leadership. All these building blocks and the constructive critics of them formed the foundations for the development and elaboration of the multistep flow of communication.
Diffusion Theories: Logic and Role of Media
Authors: Barnett George A. , Vishwanath Arun
Published: March 2017

Diffusion is the process by which new products, behaviors, or ideas are communicated among the members of social systems. This entry describes what is known about the process of the diffusion of innovations and the dissemination of information through the mass media. It differentiates the roles of the media (mass and digital) and interpersonal communication using a series of mathematical models. It then goes on to describe adopter categories and how attributes of innovations, news, and technology clusters impact the process.
Sexuality and Sexual Health: Media Influence on
Authors: Aubrey Jennifer Stevens , Gamble Hilary
Published: March 2017

An extensive amount of research on media's influence on sexuality has been published since the late 1990s and the first decade of the twenty‐first century. Several impressive longitudinal studies of US adolescents have shown that exposure to sexually oriented television predicts initiation of sexual activities. This entry reviews that evidence, as well as evidence from other research lines—namely research investigating media's influence on adolescents' sexual risk taking and sexual self‐image and research on the sexualization of women and girls. Finally, the implications of these research lines for theorizing about future directions in new media effects on sexuality are also reviewed.
Prosocial Media Use and Effects
Authors: Mares Marie‐Louise , Stephenson Laura J.
Published: March 2017

Research on prosocial media effects has examined the use of media to foster altruistic behaviors such as helping and generosity, as well as friendly attitudes and behaviors, aggression reduction, positivity toward social out‐groups, and honesty. Overall, the research suggests that TV and other media content can foster prosocial attitudes and responses among both children and adults. However, positive effects on young viewers often seem to require more than unaided, self‐selected exposure. Effects have been observed across a variety of media, including television and film, video games, music with prosocial lyrics, and print stories.
Cyberbullying
Authors: Festl Ruth , Quandt Thorsten
Published: March 2017

Cyberbullying is a problematic form of online communication between two or more persons, typically involving aspects such as harassment, humiliation, insults, or threats. Despite being multifaceted, it can be differentiated from similar forms of online risk (e.g., sexual harassment). Research on cyberbullying is interdisciplinary, ranging from pedagogical analysis through psychological studies to approaches rooted in communication studies. In the present entry the dimensions of cyberbullying as well as the main approaches to it taken in research are discussed. Neglected research areas are summarized, along with desiderata related to them. On the basis of this review, pathways for future research are identified.
Virtual and Augmented Reality
Authors: Oh Soo Youn , Bailenson Jeremy
Published: March 2017

Virtual reality (VR) and augmented reality (AR) allow individuals to transcend physical constraints and communicate in a space where transformations of one's self‐representation and surroundings are effortless and free. In this entry readers will be introduced to the technological components of VR related to tracking, rendering, and display that make such transformations possible. Readers will also gain a deeper understanding of two concepts that are critical to the virtual experience: immersion and presence. The entry highlights the differences between VR and AR and describes the theoretical and practical applications of VR in fields such as nonverbal, health, speech, and environmental communication. Future areas for research and the ethical implications of VR and AR are also discussed.
Media Literacy
Authors: Opree Suzanna J.
Published: March 2017

This entry describes the field of media literacy. Multidisciplinary in its nature, the field of media literacy is rich in both ideas and controversies. This entry highlights differences in the approach to media literacy (definitions and interventions) between parents and teachers, teachers and scholars, and scholars themselves. Their distinctively different views may complement each other and, collectively, they can help determine how to effectively reduce media's negative effects, while instigating positive outcomes.
Quality
Authors: Maurer Torsten
Published: March 2017

The term
quality
is used with regard to the assessment of media content. Such assessments can have various foci—for example take different subjects, use different criteria, and reach different results, that is, be positive or negative. In any case, quality is not an isolated characteristic; it is a relation between a characteristic and a set of values. This set of values differs according to the perspective of the assessment. One can broadly differentiate between two perspectives: the perspective of society as a whole, where the requirements for the evaluation of quality are derived from universal social norms and where criteria like relevance, diversity, or objectivity are used; and the perspective of single individuals, where the connection between recipients' assessments of quality and their overall usage behavior is of particular interest.
Selective Perception and Retention
Authors: Stroud Natalie Jomini , Choi Sohyun
Published: March 2017

From the early days of modern media effects research, scholars have identified selective perception and retention as limitations on the media's effect. These selectivity processes involve perceiving and remembering messages through the lens of one's existing beliefs and attitudes. The accumulated evidence suggests that these processes are widespread. When people process messages, whether about science, politics, health, comedy, or the media in general, their predispositions condition the effect of the message. Despite the prevalence of these processes, however, recent research suggests that selective perception and retention do not always occur. Identifying when and why these psychological processes limit the effects of media messages provides a promising path for continued research on media effects.
Motivation
Authors: Rieger Diana , Vorderer Peter
Published: March 2017

The motivational question in media research tries to reach beyond the simple description of who is doing what in which kind of situation; it rather attempts to explain why things are done as they are done. This entry systematizes various answers to the question of why users turn to media, how they differ with regard to the circumstances under which they want to be entertained or informed, and why it is rewarding for them to be engaged with media content. The entry describes different perspectives as to why people turn to media and explains the motivational roots of engaging with media from an intentionalist and from an objectivist perspective. It concludes with an application of established theories of motivation to new forms of media (e.g., social media and mobile media).
Adaptive Structuration Theory
Authors: Rains Stephen A. , Bonito Joseph A.
Published: March 2017

Adaptive structuration theory (AST) offers an explanation for the use and effects of technologies in organizations. AST focuses on the dynamic relationship between the structures provided by technologies (e.g., document sharing) and the ways in which those structures are used by organizational members (e.g., collaboratively produced documents). The outcomes of technology use are ultimately contingent upon the way in which structures are appropriated (e.g., some groups might choose to work on a document in series, others in parallel). An overview of AST is provided including a discussion of its conceptual foundation, core components, applications, and critiques of the theory.
Alternative Forms of Organization and Organizing
Authors: Cheney George , Munshi Debashish
Published: March 2017

The concepts of alternative forms of organization and organizing are germane to organizational studies writ large and to the subfield of organizational communication. Here we interrogate the ambiguity of the terms themselves while also considering the family resemblances of organizational forms under this rubric. The discussion proceeds with an explanation of values, principles, and models of alternative organizations and organizing. A variety of research exemplars are cited. Issues for further research are identified throughout.
Alternative Work Arrangements
Authors: Golden Annis G. , Elia Alana R.
Published: March 2017

Alternative work arrangements are any form of employment that does not conform to conventional norms with respect to where, when, and how work is performed. Various contemporary socioeconomic factors make such work increasingly common. The impact of these arrangements on organizational processes like socialization and identification, and their relationship to new communication technologies and work–life interrelationships, are matters of significant interest in organizational communication.
Anonymous Organizational Communication
Authors: Scott Craig R. , Haseki Müge , Kang Kyungwon
Published: March 2017

Anonymous organizational communication refers to any communication creating, maintaining, or otherwise relevant to the organization where the message source is not named. This anonymity is a matter of degree shaped primarily by the extent to which a source is perceived asunknownandunspecified(the source cannot be limited to some specific subset of possible communicators). Scholarship points to a wide range of activities where anonymity may be found in organizations – including feedback, reporting of wrongdoing, and efforts by organizations and their members to conceal their identity from various audiences. In general, it may be used for constructive and destructive purposes. Various communication technologies may play a key role to not only provide a sense of anonymity but also track and identify organizational members. In a digital age when calls for openness and transparency confront a desire for privacy by organizations and their members, anonymous communication demands increased attention.
Authority
Authors: Benoit‐Barné Chantal , Fox Stephanie
Published: March 2017

Authority refers to a legitimate form of power that sustains integration, predictability, and order within organizations. How authority derives its perceived legitimacy is a key issue that to some extent structures the field of inquiry. In the organizational communication literature, this issue has been addressed in different ways, broadly grouped into three themes: (1) the authority to decide and to co‐create meaning, (2) the performance of authority, and (3) authoring the organization. Discussion of each theme shows a tendency to move from static to more dynamic views of authority as well as an increased interest in authority as an organizational communication phenomenon.
Boundary Spanning
Authors: Nelson‐Marsh Natalie
Published: March 2017

Boundary spanning is a communication activity by which individuals connect an organization to its environment. This construct has enjoyed a long history of exploration from various theoretical and methodological approaches. Historically, researchers utilized network analysis and quantitative measures to examine boundary spanning. This research focused on the network position of an individual, and characterized boundary spanners as experts who collected information from the external environment and disseminated this information internally. Since the 1970s there has been an increase in the creation and participation in new interorganizational relationships (IORs) including
boundary organizations
, which serve as contemporary spaces for boundary spanners to connect organizations to the environment and collectively solve complex problems. Current research in organizational communication utilizes qualitative and dialogic approaches to extend what is known about boundary spanning. This research develops the roles boundary spanners play and the different discourses that sustain these interorganizational spaces as interorganizational collaboration (IOC).
Branding
Authors: McDonald James
Published: March 2017

Branding refers to strategic discourse that seeks to shape meaning in ways that are aimed at value creation. Although branding has long been explored in marketing research, it has only recently come into the purview of organizational communication scholarship. This entry outlines the place of branding in organizational scholarship, as well as the distinct ways through which organizational communication scholars have approached the study of branding. More specifically, the entry first conceptualizes branding as a communicative accomplishment that has important implications for power, control, and identity in organizational life. Afterwards, the entry outlines the three types of branding that have been most explored in organizational communication research: corporate branding, personal branding, and occupational branding. The entry concludes by exploring recent developments in the study of branding, as well as future directions for organizational communication research on branding.
Business Communication
Authors: Violanti Michelle T.
Published: March 2017

Business and professional communication, one aspect of organizational communication, involves intentional messages voluntarily exchanged between two or more people in for‐profit companies. Business and professional communication instruction addresses written communication (résumés, cover letters, proposals, reports, formal performance feedback, and electronic messages such as email and material posted online), oral communication (interpersonal, small group or team, and public speaking), and listening. In practice, business and professional communication includes leadership and followership, group decision making processes, and feedback. Constructivism, expectancy violation theory, and social presence theory represent three ways to explain and predict business and professional communication. The multigenerational, co‐cultural workplace with its increasingly diverse options for creating and delivering messages requires lifelong learning for all employees.
Change, Organizational
Authors: Lewis Laurie , Sahay Surabhi
Published: March 2017

Organizational change concerns altered or disrupted states in organizations. Scholars have suggested various change models and documented how communicative relationships and actions play an important role in change. Research has primarily sought to understand managers' needs in change processes that are often focused on dissemination of information and framing of change in order to reduce uncertainty and resistance. Communication research has focused on a variety of stakeholders' communicative interactions surrounding change and noted that change and change processes are socially constructed. Key communicative processes of sensemaking, conflict, persuasion, dissent expression, and upward influence shape the course of change in organizations.
Channels
Authors: Porter Amanda J.
Published: March 2017

Channels are a means through which people communicate in organizations. Communication channels are important because the core functions of organizations, such as processing information or making and communicating decisions, occur through communication channels. Theories of channel selection show that organizations can be improved if organizational members learn how and when to use the most appropriate channel. New information and communication technologies offer organizations more diverse options for channels of communication.