David B. Knight

Contribution of tropical cyclones to extreme rainfall events in the southeastern United States

Extreme precipitation has been increasing in the United States over the past century. In light of the associated impacts and possible linkages to climate change, this topic has garnered a great deal of attention from the scientific community and general public. Because tropical cyclones are a common source of heavy rainfall in the southeastern United States, we examined the contribution of tropical cyclone precipitation relative to overall extreme precipitation from all weather systems combined. We used a surface observation network over the period 1972-2007, consisting of first-order and Cooperative Observer Program weather stations. Furthermore, to account for precipitation that may be unmeasured by rain gauges because of windy conditions during tropical cyclones, we employed a wind-corrected data set and the North American Regional Reanalysis. According to several metrics of extreme precipitation, we found that extreme precipitation from tropical cyclones has been increasing over the past few decades. Additionally, the contribution of tropical cyclone precipitation to overall extreme precipitation has been significantly increasing by approximately 5%-10% per decade in the southeastern Atlantic coastal states. We attribute this rise in tropical cyclone contribution to an increase in both the storm wetness (precipitation per storm) and storm frequency over the period of record. There is little evidence that changes in storm duration are responsible for the increase. As such, we believe that an important factor in accurately projecting changes in extreme precipitation rests on whether tropical cyclone activity is driven more by natural decadal oscillations or by large-scale warming of the environment.

Climatology of Tropical Cyclone Rainfall in the Southeastern United States

Rainfall associated with tropical cyclones contributes a significant amount to the annual rainfall in the southeastern United States. This study quantifies this amount from 1980-2004 as we compare the total rainfall to an amount excluding rainfall arising from tropical cyclones. Additionally, we use these precipitation amounts to examine the climatic water balance and observed hurricane-season moisture deficits and compare actual deficits to deficits with tropical cyclone rainfall removed. Tropical cyclones contribute as much as 15% of the hurricane-season rainfall along portions of the Carolinas. The Appalachian Mountains act as a barrier to the inland influence of tropical cyclone rainfall and generate a spatial rainfall gradient on mean precipitation maps. Within a hurricane-season, the percentage of rainfall that can be attributed to tropical cyclones tends to progress eastward throughout the season. Temporally, rainfall from tropical cyclones has increased over much of the region, while nontropical cyclone rainfall has largely remained unchanged. With respect to the water balance, soil moisture deficits would significantly increase if the southeastern United States did not receive rainfall from tropical cyclones. This would have consequences for the agricultural community and would increase the reliance on irrigation in agricultural production.

Increasing frequencies of warm and humid air masses over the conterminous United States from 1948 to 2005

Time series of individual climate variables, such as air temperature and precipitation, have been thoroughly examined to evaluate climate change, but few studies have evaluated how air masses have varied over time. We use the Spatial Synoptic Classification air mass approach to classify multivariate meteorological surface variables into discrete groups and examine trends in air mass frequencies over the period 1948-2005 for the continental United States. We observe increases in warm, moist air masses at the expense of cold, dry air masses, consistent with expectations in an atmosphere with increasing greenhouse gas concentrations. Temporal variations in the North Atlantic Oscillation, Pacific/North American teleconnection pattern, Arctic Oscillation, and El Nino-Southern Oscillation partially explain some of these observed trends in winter.

Identifying threshold concepts: case study of an open catchment hydraulics course

The Threshold Concept Framework is used to initiate a dialogue on an empirically supported pedagogy that focuses on students’ conceptual understanding required for solving application-based problems. The present paper uses a triangulation approach to identify the threshold concept in a third-year undergraduate civil engineering course on open channel hydraulics. Evidence from teachers, students, and assessment data point to ‘critical flow’ as the threshold concept – a concept that is transformative, integrative, and troublesome. Identifying the threshold concept by engaging various course stakeholders in a dialogue about conceptual understanding and capabilities makes learning visible for all participants in the process. Implementing this approach can result in an empirically driven rationale for adjusting pedagogies and assessments to foster enhanced student learning outcomes.

A respiratory alert model for the Shenandoah Valley, Virginia, USA

Respiratory morbidity (particularly COPD and asthma) can be influenced by short-term weather fluctuations that affect air quality and lung function. We developed a model to evaluate meteorological conditions associated with respiratory hospital admissions in the Shenandoah Valley of Virginia, USA. We generated ensembles of classification trees based on six years of respiratory-related hospital admissions (64,620 cases) and a suite of 83 potential environmental predictor variables. As our goal was to identify short-term weather linkages to high admission periods, the dependent variable was formulated as a binary classification of five-day moving average respiratory admission departures from the seasonal mean value. Accounting for seasonality removed the long-term apparent inverse relationship between temperature and admissions. We generated eight total models specific to the northern and southern portions of the valley for each season. All eight models demonstrate predictive skill (mean odds ratio = 3.635) when evaluated using a randomization procedure. The predictor variables selected by the ensembling algorithm vary across models, and both meteorological and air quality variables are included. In general, the models indicate complex linkages between respiratory health and environmental conditions that may be difficult to identify using more traditional approaches.

What to do with a Threshold Concept

At a general level we would argue that programmes [of study] should be designed and systematically reviewed according to … the processes through which learners are made ready for, approach, recognise, and internalise threshold concepts.

Diverging Revenues, Cascading Expenditures, and Ensuing Subsidies: The Unbalanced and Growing Financial Strain of Intercollegiate Athletics on Universities and Their Students

We present a three-part conceptual model that illuminates key dynamics promoting financial unsustainability within intercollegiate athletics. Revenue divergence comprises the first part as the influx of commercial athletic revenues primarily benefits a small set of universities housing prominent athletic programs. These schools then increase athletic expenditures, which promotes expenditures cascades as their spending spurs expenditure growth at other athletic programs. Because external revenues do not increase alongside expenditures at these other programs, subsidies ensue as student fees and institutional subsidies are increased to fill growing deficits. These increases, however, will be difficult to sustain in an era of tight academic budgets and rising student debt. We describe each part of the model using a range of organizational theories and use financial data from intercollegiate athletic programs to demonstrate that the patterns predicted by our framework are supported empirically.

Threshold concepts as a focus for metalearning activity: application of a research-developed mechanism in undergraduate engineering

This paper reports on the development of metalearning capacity in the learning of a threshold concept – capacity of transformative significance relative to metalearning in the general response context of a discipline or subject. The development of metalearning capacity is framed within a protocol that invites students to self-construct a ‘learning profile’ of themselves; reflect on it in light of theoretical considerations; and accordingly self-initiate changes to their learning behaviour. Findings are consistent with other studies in different disciplinary contexts that employed the same methodology – namely, that metalearning activity can be successfully focused on a particular threshold concept to benefit a substantial majority of students in a variety of ways ranging across a positive reinforcement of self, a change in conception of what ‘learning is’, to self-initiated change. Metalearning activity is advocated as a theoretically sound, and pedagogically driven, learning intervention – one that adds value to the student learning experience.

Reversing the Logic: An Outcomes-Based Student Typology for Determining “What Works” in Promoting an Array of Engineering-Related Student Learning Outcomes

Colleges and universities are being pressed to seek innovative ways to measure student learning outcomes and identify the conditions that lead to their development. Understanding how students group according to a multidimensional set of learning outcomes provides information on the extent to which institutions are meeting goals. This study develops a typology based on engineering undergraduates’ array of outcomes. The study also demonstrates variation in personal and educational experiences across outcomes-based student groupings, thus providing insight into “what works” for programs who seek to graduate students who have developed an array of engineering-related outcomes. This outcomes-based approach is readily applicable to any set of student learning outcomes that programs or institutions seek to cultivate.

Enhancing the Teaching and Learning of Biometeorology in Higher Education

This meeting was the result of a 2015 proposal to the Tromp Foundation (foundation for biometeorological research) within the International Society of Biometeorology (ISB) where opportunities were identified for gaining critical insight into the prospects of the incorporation of biometeorology into higher education. Specific topics were highlighted regarding how to effectively integrate biometeorological concepts, learning modules, and pedagogical techniques into undergraduate and graduate courses and curricula worldwide—and to learn the best practices by which to do so.