298 research outputs found
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The genesis and development of mobile learning in Europe
In the past two decades, European researchers have conducted many significant mobile learning projects. The chapter explores how these projects have arisen and what each one has contributed, so as to show the driving forces and outcomes of European innovation in mobile learning. The authors identify context as a central construct in European researchers’ conceptualizations of mobile learning and examine theories of learning for the mobile world, based on physical, technological, conceptual, social and temporal mobility. The authors also examine the impacts of mobile learning research on educational practices and the implications for policy. Finally, they suggest future challenges for researchers, developers and policy makers in shaping the future of mobile learning
Innovation in Mobile Learning: A European Perspective
In the evolving landscape of mobile learning, European researchers have conducted significant mobile learning projects, representing a distinct perspective on mobile learning research and development. Our paper aims to explore how these projects have arisen, showing the driving forces of European innovation in mobile learning. We propose context as a central construct in mobile learning and examine theories of learning for the mobile world, based on physical, technological, conceptual, social and temporal mobility. We also examine the impacts of mobile learning research on educational practices and the implications for policy. Throughout, we identify lessons learnt from European experiences to date
Forecasting the Air Race Classic: Lessons in Interdisciplinary Aviation Weather Support and Decision-Making
The Air Race Classic (ARC) is an all-female Visual Flight Rules air race held each June. Embry-Riddle Aeronautical University Daytona Beach (ERAU-DB) has had primarily student race teams participate and frequently place strongly in the ARC since 1996. The ERAU-DB Meteorology Program has provided successful weather support to ERAU-DB race team(s) for the past decade, including as the terminus host institution in 2016. In 2014, the weather support was formalized as a three-credit interdisciplinary summer course, incorporating a mix of aeronautical science (pilot), dispatch, and meteorology students. Using concepts of service and experiential learning, the ARC course has successfully integrated students from varying educational backgrounds into cohesive weather support teams that serve the ERAU-DB air racers. As such, students from primarily aviation backgrounds have had to learn about aviation weather support tools and techniques they were not previously aware of, while students from primarily meteorological backgrounds had to integrate aviation concepts such as fuel burn and service ceiling into their forecasts. The ARC weather support experience has helped to expose students to real-world situations and decision-making, given them an increased sense of purpose and service to the ERAU-DB community, and improved their ability to combine aviation and meteorological thinking for the purpose of real-time aviation weather forecasting
New Metric for Defining the Time of Extratropical Transition of Tropical Cyclones
Almost half of all tropical cyclones (TCs) in the Atlantic basin undergo extratropical transition (ET). During an ET event, wind fields often expand dramatically, resulting in more widely-felt impacts. Moreover, the heaviest precipitation typically shifts to the left-of-center (LOC), which can result in inland flash flooding hundreds of kilometers from the cyclone center. While several objective metrics to track and predict ET have been developed, they rely at least partially on internal tropical cyclone structure, for which numerical models show less skill. Further, these metrics fail to account for static stability, which plays a vital role in determining precipitation amounts. In this study, a coupled dynamic and thermodynamic metric using the eady moist baroclinic growth rate (EMBGR) is proposed to define the time of ET. The EMBGR parameter relies on well forecasted environmental flow characteristics and static stability. The time of ET deduced from the EMBGR is then compared using different methods i.e. HURDAT, storm precipitation distribution (left or right of center), interaction between the mid-latitude trough and tropical system from a vorticity perspective, and the Cyclone Phase Space
Assessing Vulnerability to Heat Stress Trends in the Southeast United States
The 4th National Climate Assessment identified extreme heat as a pressing threat to human health in the Southeast U.S. Adverse health impacts are exacerbated throughout the region by climate change, an older and rapidly growing population, and dramatic urbanization. Furthermore, extreme heat disproportionately affects disadvantaged groups, lower-income individuals, and workers in industries that require outdoor labor (e.g., agriculture). This disparity is particularly evident in densely populated metropolitan areas. For human health applications, wet bulb globe temperature (WBGT) has been shown to be the most representative heat stress metric for human health impacts. Using WBGT and relative (percentile-based) thresholds for extremes, this study first investigates trends in summer heat stress at more than 100 ASOS stations throughout the Southeast U.S. To identify which communities in the region are most vulnerable to increasing heat stress, the Centers for Disease Control (CDC) social vulnerability index (SVI) will be incorporated. The SVI uses county and census-tract level demographic, social, and economic metrics to identify at-risk communities. Combining the WBGT trends for 100+ ASOS stations with the SVI, a Southeast U.S. map created with ArcGIS Pro will be used to show the locations that face the biggest impacts from heat stress. Based on the combination of the SVI and heat stress trends, a numerical rating scale will be developed to show the areas that are most impacted by the dual threat of extreme heat and social vulnerability
Composite Analysis of Cool-Season Florida Tornado Outbreaks
The study of tornado outbreaks has been well documented, however, there has only been a few on Florida tornado outbreaks. This study details the composite dynamic and thermodynamic conditions associated with these events. Consistent with past research, a tornado outbreak was defined as 4 or more tornadoes occurring within a 24-h period during the winter and early spring months (Dec–May) from 1979–2016. December–May was chosen to eliminate tornado outbreaks that were associated with tropical cyclones.
In total, 35 outbreaks were identified using archived severe weather reports. Composites were produced using the North American Regional Reanalysis (NARR).Initial results show Florida tornado outbreaks are associated with a negatively tilted mid-tropospheric trough (dynamics), moderate CAPE and low LCLs (thermodynamics), strong lower-tropospheric wind shear, and the upper-level divergent exit region of the Polar Front Jet (PFJ)
A Diagnostic Metric for Predicting Tropical Cyclone and Mid-Latitude Floods
This study details a dynamic and thermodynamic metric (i.e., Extreme Flood Index [EFI]) designed to diagnose the frequency and intensity of extreme precipitation events associated with stagnant mid-latitude flow patterns (i.e., Rex blocks). As the global climate warms, rapid Arctic warming may be helping to slow the mid-latitude westerly jet stream, resulting in increased mid-latitude flow stagnation. The combination of long-duration ascent associated with easterly winds and warm moist air increases the severity of extreme precipitation events; as such, the EFI is specifically designed to detect this potent combination of ingredients. In 2013, a Rex block stalled a low-pressure system over Alberta which caused the worst Canadian flood disaster ever seen. To that end, the recent billion-dollar flood catastrophe produced by Tropical Cyclone (TC) Harvey was also associated with a Rex Block (dynamics) in the presence of warm, moist air (thermodynamics). Despite dynamic differences between TC-related and mid-latitude floods, the EFI is successfully able to detect both. The dynamics component of the EFI is derived from two atmospheric blocking criteria, used operationally by the European Centre for Medium-Range Weather Forecasts (ECMWF) and National Oceanic and Atmospheric Administration (NOAA), respectively, and adapted here for the shorter duration of extreme precipitation events. The EFI’s thermodynamic component utilizes standardized anomalies of equivalent potential temperature. Finally, the ability of the EFI to diagnose and predict high-impact flood events using reanalysis data and operational numerical weather prediction models is explored
An Analysis of the First Ever DOW-Observed Mesolow
Embry-Riddle Aeronautical University Convective-Boundary Research Engaging Educational Student Experiences 2.0 (ERAU CBREESE 2.0) was a 15-day Doppler-on-Wheels (DOW) and Mobile Mesonet educational deployment from the Center for Severe Weather Research (CSWR). Building off the success of ERAU CBREESE in May 2015, the educational deployment was designed to observe and measure sea-breeze processes and convection, with a specific focus on Central Florida sub-regions that contain multiple mesoscale breezes and boundary collisions. On 6 July 2018, the first-ever DOW-observed mesolow was recorded along the Space Coast near Titusville, Florida. The purpose of this study was to examine the ability of the High-Resolution Rapid Refresh (HRRR) model to accurately diagnose and forecast this feature. After calculating the height of the DOW beam at each elevation scan, it was noted that the mesolow was predominantly observed in the 900–600-hPa layer. The 20 UTC HRRR analysis shows that the mesolow circulation was resolved by the model as it occurred. Since the HRRR explicitly diagnoses and forecasts many variables that other models, such as the Global Forecast System (GFS), are only able to parameterize, this also yielded the opportunity to explore what mechanisms may have contributed to the initial formation of the mesolow
Synoptic-Scale Precursors, Characteristics and Typing of Nocturnal Mesoscale Convective Complexes in the Great Plains
Mesoscale convective complexes (MCCs) occur frequently during the warm season in the central U.S. and can produce flooding rains, hail and tornadoes. Previous work has found that the synoptic-scale environment can greatly affect, and be affected by, the development and maintenance of MCCs. Ninetytwo MCC cases from 2006–2011 are manually identified using infrared satellite imagery and partitioned into three types (upstream trough, zonal and ridge) using a unique manual synoptic typing based on 500- hPa height patterns. Upstream trough cases feature an amplified longwave 500-hPa trough upstream of the MCC genesis region (GR), while the 500-hPa flow is relatively flat in zonal cases, and a strong 500-hPa ridge is present over the Rockies in ridge cases. Individual case and storm-relative composite analyses of a subset of 28 cases show that of the three types, upstream trough cases feature both the strongest quasigeostrophic forcing for ascent and lower-tropospheric frontogenesis, the latter of which enhances ascent and is associated with a strong southerly low-level jet (LLJ). Zonal and ridge cases feature smaller magnitudes (in descending order) of all ascent-forcing parameters. Ridge cases, in particular, are characterized by weak Q-vector convergence, but easterly upslope flow likely acts as a compensating ascent mechanism. A thermodynamic analysis shows that high-θe air is advected into the GR in all three MCC types, and serves as fuel for development and maintenance. However, while the southerly LLJ advects high-θe air from the Gulf of Mexico in the upstream trough and zonal cases, such air is already pooled in the High Plains in the ridge cases and advected into the GR by easterly flow. In accordance with the synoptic-dynamic analysis, upstream trough cases have the longest duration and largest impact on the synoptic-scale environment, while ridge cases are the shortest-lived. The various underlying precipitation structures of each group are also explored; zonal cases, for example, appear to preferentially be associated with bow echoes
A Thermodynamic Analysis of an Intense North American Arctic Air Mass
Northwestern Canada is a genesis region of arctic air masses often considered to be formed primarily through radiative processes. However, the details of their life cycle are poorly understood. This paper examines the formation, maintenance, and dissipation of an intense and long-lived arctic air mass, using a thermodynamic budget analysis.
The airmass formation is characterized by a deep-layer, multistage process that begins with snow falling into a nascent air mass. Radiative cooling from cloud tops begins the process. After the snow abates and clear skies are observed, the surface temperature drops rapidly, aided by the high emissivity of fresh snow cover, falling 178C in two days, creating an intense but shallow temperature inversion. Once the surface temperature falls below the frost point, ice crystals form. Afterward, although the surface temperature remains constant, the height of the inversion rises, as radiative cooling at the top of the ice fog layer decreases temperatures.
During the maintenance phase, a cold-air damming structure is present with an anticyclone in the lee of the Canadian Rockies, low pressure in the Gulf of Alaska, and an intense baroclinic zone parallel to the mountains, separating warmer maritime air from colder continental air. The air mass persists for 12 days, undergoing several cycles of deep-layer weakening and intensification
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