scholarly journals Fire-Generated Tornadic Vortices

2021 ◽  
Author(s):  
Neil Lareau ◽  
Nicholas Nauslar ◽  
Evan Bentley ◽  
Matthew Roberts ◽  
Sammuel Emmerson ◽  
...  

Fire-generated tornadic vortices (FGTVs) linked to pyrocumulonimbi (pyroCb) are a potentially deadly, yet poorly understood and seldom observed wildfire hazard. In this study we use radar and satellite observations to examine three FGTV cases during high impact wildfires during the 2020 fire season in California, USA. We establish that these FGTVs each exhibit tornado-strength anticyclonic rotation, with rotational velocity as strong as 30 m s-1 (60 kts), vortex depths of up to 5 km AGL, and pyroCb plume tops as high as 16 km MSL. These data suggest similarities to EF2+ strength tornadoes. Volumetric renderings of vortex and plume morphology reveal two types of vortices: embedded vortices anchored to the fire and residing within high reflectivity convective columns and shedding vortices that detach from the fire and move downstream. Time-averaged radar data further show that each case exhibits fire-generated meso-scale flow perturbations characterized by flow splitting around the fire’s updraft and pronounced flow reversal in the updraft’s lee. All the FGTVs occur during deep-pyroconvection, including pyroCb, suggesting an important role of both fire and cloud processes. The commonalities in plume and vortex morphology provide the basis for a conceptual model describing when, where, and why these FGTVs form.

2021 ◽  
Author(s):  
Neil Lareau ◽  
Nicholas Nauslar ◽  
Evan Bentley ◽  
Matthew Roberts ◽  
Sammuel Emmerson ◽  
...  

Fire-generated tornadic vortices (FGTVs) linked to pyrocumulonimbi (pyroCb) are a potentially deadly, yet poorly understood and seldom observed wildfire hazard. In this study we use radar and satellite observations to examine three FGTV cases during high impact wildfires during the 2020 fire season in California, USA. We establish that these FGTVs each exhibit tornado-strength anticyclonic rotation, with rotational velocity as strong as 30 m s-1 (60 kts), vortex depths of up to 5 km AGL, and pyroCb plume tops as high as 16 km MSL. These data suggest similarities to EF2+ strength tornadoes. Volumetric renderings of vortex and plume morphology reveal two types of vortices: embedded vortices anchored to the fire and residing within high reflectivity convective columns and shedding vortices that detach from the fire and move downstream. Time-averaged radar data further show that each case exhibits fire-generated meso-scale flow perturbations characterized by flow splitting around the fire’s updraft and pronounced flow reversal in the updraft’s lee. All the FGTVs occur during deep-pyroconvection, including pyroCb, suggesting an important role of both fire and cloud processes. The commonalities in plume and vortex morphology provide the basis for a conceptual model describing when, where, and why these FGTVs form.


Forests ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 522
Author(s):  
Akli Benali ◽  
Ana C. L. Sá ◽  
João Pinho ◽  
Paulo M. Fernandes ◽  
José M. C. Pereira

The extreme 2017 fire season in Portugal led to widespread recognition of the need for a paradigm shift in forest and wildfire management. We focused our study on Alvares, a parish in central Portugal located in a fire-prone area, which had 60% of its area burned in 2017. We evaluated how different fuel treatment strategies may reduce wildfire hazard in Alvares through (i) a fuel break network with different extents corresponding to different levels of priority and (ii) random fuel treatments resulting from a potential increase in stand-level management intensity. To assess this, we developed a stochastic wildfire simulation system (FUNC-SIM) that integrates uncertainties in fuel distribution over the landscape. If the landscape remains unchanged, Alvares will have large burn probabilities in the north, northeast and center-east areas of the parish that are very often associated with high fireline intensities. The different fuel treatment scenarios decreased burned area between 12.1–31.2%, resulting from 1–4.6% increases in the annual treatment area and reduced the likelihood of wildfires larger than 5000 ha by 10–40%. On average, simulated burned area decreased 0.22% per each ha treated, and cost-effectiveness decreased with increasing area treated. Overall, both fuel treatment strategies effectively reduced wildfire hazard and should be part of a larger, holistic and integrated plan to reduce the vulnerability of the Alvares parish to wildfires.


2014 ◽  
Vol 28 (6) ◽  
pp. 484-497 ◽  
Author(s):  
Bang Nguyen ◽  
Philipp “Phil” Klaus ◽  
Lyndon Simkin

Purpose – The purpose of this study is to (a) develop a conceptual framework exploring the relationships between perceived negative firm customization, unfairness perceptions, and customer loyalty intentions, and (b) investigate the moderating effects of trust in these relationships. The study explores how customizing offers to match customers’ individual needs and how treating customers differentially provoke unfairness perceptions among those not being considered most important. While the literature discusses unfairness perceptions of pricing, promotion, and service, less is known about unfairness in customization practices. Design/methodology/approach – Using a survey approach, 443 completed questionnaires we collected. Following validation of our item measures, a hierarchical linear regression analysis was conducted to test the conceptual model and hypothesized linkages between our constructs. Findings – The results demonstrate that customers’ negative perceptions of customization increase their unfairness perceptions. Unfairness perceptions drastically reduce customer loyalty intentions with trust acting as a significant moderator. Trust increases loyalty intentions even when unfairness perceptions are present. Our findings provide a foundation for understanding how firms may improve their perceived fairness. This increase in perceived fairness creates positive attributions, reduces negative customer experience perceptions and increases loyalty intentions. Originality/value – Key contribution is the development and validation of a conceptual model explaining the linkages between firm customization and unfairness perceptions, firm customization and customer loyalty intentions and the moderating role of trust between these relationships. This study extends the understanding of how customization practices impact unfairness perceptions and, subsequently, influence consumers’ perceptions, intentions and behavior.


2018 ◽  
Vol 35 (3) ◽  
pp. 300-316 ◽  
Author(s):  
Debora Bettiga ◽  
Lucio Lamberti

Purpose This study aims to explore the role of positive and negative anticipated emotions on adoption and continued usage of consumer products. The components of value eliciting anticipated emotions are investigated as well. Design/methodology/approach The conceptual model proposed is tested in two empirical studies, one focussing on functional and hedonic products and one on incremental and radical product innovations. Data are collected through online surveys on consumers and are analysed using structural equation modelling. Findings Results confirm the ability of anticipated emotions to influence product decision-making process. Moreover, anticipated emotions mediate the influence of value perceptions on product attitude. Findings show that these relationships vary greatly between initial adoption and further usage of the product. Practical implications Findings from this study may help marketers in the development of the right brand strategies and communication campaigns, aimed at building emotional connections with the consumer which prompt product adoption and usage. Originality/value Anticipated emotions, the predictions about the emotional consequences of a behaviour, have been acknowledged as strong drivers of consumer choices. Despite that, the role of anticipated emotions in product decision-making has not been explored yet. The present research, by means of a novel conceptual model, uncovers the role of anticipated emotions in both product adoption and continued usage decisions and depicts the components of value arousing such anticipated emotions.


2017 ◽  
Vol 13 (3) ◽  
pp. 215-225 ◽  
Author(s):  
Louis Tay ◽  
James O. Pawelski ◽  
Melissa G. Keith

2021 ◽  
Author(s):  
Hitoshi Kaneko ◽  
Ken'ichi Sasaki ◽  
Hiroto Abe ◽  
Shuichi Watanabe ◽  
Yoshiaki Sato

2021 ◽  
Author(s):  
Mónica Ribau ◽  
Rui Perdigão ◽  
Julia Hall

<p>Strategic narratives (persuasive use of story systems) in science communication have been gathering<br>increasing support, especially in the face of misunderstandings about high-impact climatic change and hydrometeorologic extremes.<br>The use of these narratives reveals, in line with linguistic research, that traditional scientific discourse<br>conception has become outdated. Should scientific discourse be centered on the description of discoveries?<br>Should the role of political discourse be to convince someone to act? Before answering these, it is necessary to<br>understand the crucial function that uncertainty plays in communication, along with its consequences in the<br>concepts of objectivity and truth. More importantly, understanding its role in scientific society and sustainability.<br>Unable to eliminate uncertainty altogether, science becomes an essential escort to recognize, manage<br>and communicate its pertinency. However, the most popular strategic narratives sideline uncertainty as a threat.<br>Denialists follow a similar approach, though they communicate uncertainty to discredit evidence. Comparatively,<br>in their latest Assessment Report, the IPCC characterized uncertainty whilst stating: “uncertainty about impacts<br>does not prevent immediate action”.<br>Scientific discourse outputs and social reality constructions influence each other. The moralization of<br>science communication reveals how XVII century revolutionary skepticism can now be perceived as a threat, and<br>facts expected from science can be deemed dogmatic truths and perceived as decrees through rationalism and as<br>an extension of Judeo-Christian philosophical influence. Equally important, uncertainty reinforces individual<br>freedom, while society grasps and recognizes certainty as security and demands it from institutions, accepting<br>degrees of authoritarianism to maintain a tolerable living condition.<br>From “Climate Emergency” to “Thousand-Year Flood”, public interest in climatic change and extremes<br>increases following high-impact events, yet trust in science plunges into a deep polarized divide among absolute<br>acceptance and outright rejection relative to the bold headlines conveyed not only in the media but also in some<br>scientific literature.<br>Political, religious and activist leaders strike one as prophets acting in the name of science. From<br>rationalism to rationality, scientific culture is pivotal to the analysis of complexity, objectivity, and uncertainty in<br>the definition of truth (absent from epistemological discussions for centuries). Humor/sarcasm, literature or<br>dialectic are examples of how to communicate entropy of scientific models, while reflecting about the role,<br>uncertainty, and mistake, retain in life.<br>“People want certainty, not knowledge”, said Bertrand Russel. However, neither science nor democracy<br>work like that, rather taking reality as having shades of grey instead of a reduced black-or-white dichotomy.<br>Science is not about giving just one single number to problems clearly not reducible to such, as that gives a false<br>sense of certainty and security in an entropic world where we cannot control everything.<br>In order to objectively analyze discourses in light of their uncertainty features, detecting whether they<br>contain polarized, absolutistic narrative patterns, we introduce a new process-consistent Artificial Intelligence<br>framework, building from Perdigão (2020, https://doi.org/10.46337/200930). The complementarity of our<br>approach relative to both social and information technologies is brought out, along with ways forward to reinforce<br>the fundamental role of uncertainty in scientific communication, and to strengthen public confidence in the<br>scientific endeavor.</p>


Author(s):  
Nader Gholi Ghorchian ◽  
Shahrooz Farjad ◽  
Ali Taghipour Zahir

As higher education plays a pivotal role in the economic well-being of modern societies, universities today are faced with increasing pressure in order to improve their accountability and performance. They have to redesign the research structure to achieve the set objectives. The present survey aimed at studying the factors and related indicators that affect the effectiveness of the research structure of the universities. The sample included 274 faculty members who were selected through stratified random method at 8 branches of Islamic Azad University in Tehran province (Iran). Research questions were: a) What key Factors influence the Effectiveness of the universities’ research structure? and b) What conceptual model can be designed? Finally, in this study using a questionnaire and factor analysis technique, eight factors were identified and ranked which contribute towards the effectiveness of research structure in universities . Finally, a conceptual model has been proposed for the universities to strengthen their research structure.


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