First-year students' achievement emotions at university: A cluster analytic approach to understand variability in attendance and attainment.

BACKGROUND: Students' initial experiences at university often shape their attendance and attainment. For some students, university is a positive experience, whereas others seemingly struggle and have more negative emotions. Unearthing distinctions in first-year students' emotionality may be valuable in understanding their academic engagement and performance. AIMS: The study's aim was to identify distinct profiles of students based on their achievement emotions and explore whether these profiles differed in university attendance and attainment. At least three emotional profiles were hypothesized (positive; moderate; negative) with a positive profile expected to display the highest attendance and attainment. SAMPLE: Participants were 294 first-year undergraduate students from a university in the United Kingdom (Mage = 19.33 years; 127 men; 162 women). METHODS: Students completed self-report measures of eight achievement emotions for general learning. Attendance and attainment data were collected from official records. Hierarchical cluster analysis was performed to profile students on their achievement emotions. Analysis of covariance explored profile differences in attendance and attainment. RESULTS: Four emotional profiles emerged: positive; moderate; negative; mixed-valence (both positive and negative activating emotions). The positive and mixed-valence groups displayed equally high attendance compared to the moderate and negative groups. The positive group obtained higher academic attainment than the mixed-valence and negative emotion groups, but not the moderate group. CONCLUSIONS: The findings highlight the diverse emotional experiences of first-year university students and the existence of co-occurring positive and negative activation emotions. This evidence may be of practical worth to educators in understanding variability in students' emotions, attendance and attainment.

The effect of rear bicycle light configurations on drivers' perception of cyclists' presence and proximity.

The optimal cycle light configuration for maximizing cyclists' conspicuity to drivers is not clear. Advances in sensor technology has led to the development of 'reactive' cycle lights that detect changes in the environment and consequently increase their flashing speed and brightness in risky situations - for example, when a rearward car is approaching - but no research has examined the effect of such lights on driver perception. The aim of the present study is to compare different cycle light configurations, including 'reactive' light technology, on drivers' ability to detect cyclists and estimate their proximity. We recruited 32 drivers to participate in two experiments, in which they viewed life-size real-world stimuli filmed from a driver's perspective in daytime and at dusk. The footage showed a cyclist on a bicycle with a rear light mounted on the seat post, in various configurations: static light, steady flashing, reactive flashing and no light. In Experiment 1, the drivers were required to detect the presence or absence of a cyclist on the road ahead as quickly as possible. In Experiment 2, they were required to estimate the distance of the cyclist from their vehicle, and to rate their confidence in their estimates. Experiment 1 revealed that drivers were quicker to detect the cyclist's presence in all rear cycle light conditions relative to the no light condition, but there were no differences in speed or accuracy across rear light conditions. Experiment 2 showed that drivers were more accurate in estimating the cyclist's proximity in the steady flashing and reactive flashing conditions, compared to static and no light conditions. Drivers were also more confident in their judgements in all rear light conditions compared to the no light condition. In conclusion, flashing rear cycle lights, regardless of reactive technology, enhanced drivers' perception of a cyclist ahead, notably in terms of their judgements of distance to that cyclist. Further investigation is needed to fully understand the impact of cycle light technology on driver perception, as well as the use of drivers' distance-to-cyclist estimates as an index of cyclists' cognitive conspicuity.

Conducting a Community-Level Needs Assessment Through Dynamic Engagement With Stakeholders.

This paper presents the process of conducting a community-wide needs assessment that initially focused on soliciting information about childcare needs of families with school-aged children. The researchers were interested in understanding whether the method designed to conduct the needs assessment helped to foster collaboration, trust, and increased participation amongst multiple levels of stakeholders and subcommunities. Utilizing community-based participatory research principles, the authors will present a 3-phase approach to gaining community support through multiple levels of stakeholder engagement. While initially the needs assessment was focused on childcare, the scope broadened to learning about other needs that families with school-aged children faced. The strategic use of Survey Ambassadors throughout the community who could access families that were typically underrepresented and could provide feedback to the researchers in real time regarding modifications to the process was vital. Lessons learned included the need for further investigation into strategic methods for gaining family voices in underrepresented populations.

The effects of an acute bout of ergometer cycling on young adults' executive function: A systematic review and meta-analysis.

Purpose: The extent to which acute exercise improves executive function (EF) remains indeterminate. The purpose of this systematic review and meta-analysis was to determine the effect of acute ergometer cycling exercise on executive function (EF), including the potential moderating effects of exercise intensity and duration, EF task type, and EF task onset. Methods: We searched seven electronic research databases using cycling- and cognition-related terms. All 17 studies included were published in the last 10 years and comprised healthy participants aged 18-35 years who completed tasks assessing a variety of EFs before and after cycling exercise lasting 10-60 min. We analyzed 293 effect sizes obtained from 494 individuals (mean age = 22.07 ± 2.46 yrs). Additional analyses were performed, using averaged effect sizes for each separate study to examine the omnibus effect across studies. Results: There was a positive effect of acute ergometer cycling exercise on response time (RT) in 16 of 17 studies reviewed and a positive effect for response accuracy (RA) in 8 of 14 studies; three studies did not report RA data. Hedges' g effect sizes [95% CI] for RT ranged from 0.06 [-0.45, 0.56] to 1.50 [0.58, 2.43] and for RA from -1.94 [-2.61, -1.28] to 1.03 [0.88, 1.19].Bouts of cycling completed at moderate intensities appear to have the greatest effect on RT (Hedges' g = 1.03 [0.88, 1.19]) but no significant effect on RA; bouts with durations of 21-30 min appear to offer the greatest benefits for both RT (Hedges' g = 0.77 [0.41, 1.13]) and RA (Hedges' g = 0.92 [0.31, 1.52]). Effect sizes were greatest for RT in inhibitory control tasks (Hedges' g = 0.91 [0.80, 1.03]) and for RT when EF tasks were completed immediately post-exercise (Hedges' g = 1.11 [0.88, 1.33]). Findings were similar in the omnibus analyses: moderate-intensity bouts had the greatest effect on RT, SMD = 0.79 (95% CI [0.49, 1.08]), z = 5.20, p < 0.0001, as did cycling durations of 21-30 min, SMD = 0.87 (95% CI [0.58, 1.15], z = 5.95, p < 0.0001. The greatest benefits were derived for inhibitory control tasks, SMD = 0.70 (95% CI [0.43, 0.98]), z = 5.07, p < 0.04, and when the EF task was completed immediately post-exercise, SMD = 0.96 (95% CI [0.51, 1.41]), z = 4.19, p < 0.001. There were no overall effects on RA. Conclusion: Our findings indicate that acute bouts of cycling exercise may be a viable means to enhance RTs in immediately subsequent EF task performance, but moderating and interactive effects of several exercise parameters must also be considered.

Endothelial-derived angiocrine factors as instructors of embryonic development.

Blood vessels are well-known to play roles in organ development and repair, primarily owing to their fundamental function in delivering oxygen and nutrients to tissues to promote their growth and homeostasis. Endothelial cells however are not merely passive conduits for carrying blood. There is now evidence that endothelial cells of the vasculature actively regulate tissue-specific development, morphogenesis and organ function, as well as playing roles in disease and cancer. Angiocrine factors are growth factors, cytokines, signaling molecules or other regulators produced directly from endothelial cells to instruct a diverse range of signaling outcomes in the cellular microenvironment, and are critical mediators of the vascular control of organ function. The roles of angiocrine signaling are only beginning to be uncovered in diverse fields such as homeostasis, regeneration, organogenesis, stem-cell maintenance, cell differentiation and tumour growth. While in some cases the specific angiocrine factor involved in these processes has been identified, in many cases the molecular identity of the angiocrine factor(s) remain to be discovered, even though the importance of angiocrine signaling has been implicated. In this review, we will specifically focus on roles for endothelial-derived angiocrine signaling in instructing tissue morphogenesis and organogenesis during embryonic and perinatal development.

Examining the New-Member Effect to an Established Community-Based Physical Activity Program for Older Adults in England.

Community-based group physical activity programs promote exercise opportunities for older people. The aim of this study was to examine the short-term, new participant effect after joining Vitality, a community-based group physical activity program available in the East of England for older adults. Two independent groups of participants were assessed before and after an 8 week period: a group recruited from the 'Vitality' program (VP) (n 15, age: Age = 69.4 ± 6.4 y), and; a non-intervention control (CON) group (n 14, age: 64.5 ± 5.8 y). Assessment outcomes included basic physical health measures, a fitness test battery, and three psychological scales. The VP group recorded statistically significant improvements on the following outcomes: body mass (VP: -1.39 kg/CON: -0.2 kg), body mass index (VP: -1.5 kg/CON: -0.2 kg), 6 min walk (VP: +42.81 m/CON: -0.45 m), 30 s sit-to-stand (VP: -1.7 s/CON: -0.7 s), the chair sit-and-reach (VP: +3.12 cm/CON: +1.90 cm), and the 30 s arm curl test (VP: + 2 reps/CON: +0.9 reps). No significant differences were found with the other outcomes assessed. New members to the Vitality program achieved several physical and functional benefits without regression on any aspects of physical or psychological health.

Factors affecting decision-making in Gaelic Football: a focus group approach.

Objectives: Research examining decision-making in sports has predominantly used experimental approaches that fail to provide a holistic understanding of the various factors that impact the decision-making process. The current study aimed to explore the decision-making processes of Senior (expert) and Academy (near-expert) Gaelic Football players using a focus group approach. Methods: Four focus groups were conducted; two with Senior players (n = 5; n = 6) and two with U17 Academy players (n = 5; n = 6). In each focus group, short video clips of Senior Gaelic football games were played, and the action was paused at key moments. The group then discussed the options available to the player in possession, the decision they would make in that situation, and importantly, what factors influenced the final decision. Thematic analysis was used to identify themes that emerged from the focus groups. Results and discussion: Four primary themes emerged that affected the decision-making process. Three themes were related to information sources, namely, pre-match context (coach tactics and instructions, match importance, and opposition status), current match context (score and time remaining), and visual information (player positioning and field space, and visual search strategy), and the fourth theme related to individual differences (self-efficacy, risk propensity, perceived pressure, physical characteristics, action capabilities, fatigue) that moderated the decision-making process. Compared to the near-expert Academy players, the expert Senior players displayed a more sophisticated understanding of the various sources of information and were able to integrate them in a more complex manner to make projections regarding future scenarios. For both groups, the decision-making process was moderated by individual differences. A schematic has been developed based on the study findings in an attempt to illustrate the hypothesized decision-making process.

Sonification of combined action observation and motor imagery: Effects on corticospinal excitability.

Action observation and motor imagery are valuable strategies for motor learning. Their simultaneous use (AOMI) increases neural activity, with related benefits for motor learning, compared to the two strategies alone. In this study, we explored how sonification influences AOMI. Twenty-five participants completed a practice block based on AOMI, motor imagery and physical execution of the same action. Participants were divided into two groups: An experimental group that practiced with sonification during AOMI (sAOMI), and a control group, which did not receive any extrinsic feedback. Corticospinal excitability at rest and during action observation and AOMI was assessed before and after practice, with and without sonification sound, to test the development of an audiomotor association. The practice block increased corticospinal excitability in all testing conditions, but sonification did not affect this. In addition, we found no differences in action observation and AOMI, irrespective of sonification. These results suggest that, at least for simple tasks, sonification of AOMI does not influence corticospinal excitability; In these conditions, sonification may have acted as a distractor. Future studies should further explore the relationship between task complexity, value of auditory information and action, to establish whether sAOMI is a valuable for motor learning.

Does sonification of action simulation training impact corticospinal excitability and audiomotor plasticity?

Sonification is a sensory augmentation strategy whereby a sound is associated with, and modulated by, movement. Evidence suggests that sonification could be a viable strategy to maximize learning and rehabilitation. Recent studies investigated sonification of action observation, reporting beneficial effects, especially in Parkinson's disease. However, research on simulation training-a training regime based on action observation and motor imagery, in which actions are internally simulated, without physical execution-suggest that action observation alone is suboptimal, compared to the combined use of action observation and motor imagery. In this study, we explored the effects of sonified action observation and motor imagery on corticospinal excitability, as well as to evaluate the extent of practice-dependent plasticity induced by this training. Nineteen participants were recruited to complete a practice session based on combined and congruent action observation and motor imagery (AOMI) and physical imitation of the same action. Prior to the beginning, participants were randomly assigned to one of two groups, one group (nine participants) completed the practice block with sonified AOMI, while the other group (ten participants) completed the practice without extrinsic auditory information and served as control group. To investigate practice-induced plasticity, participants completed two auditory paired associative stimulation (aPAS) protocols, one completed after the practice block, and another one completed alone, without additional interventions, at least 7 days before the practice. After the practice block, both groups significantly increased their corticospinal excitability, but sonification did not exert additional benefits, compared to non-sonified conditions. In addition, aPAS significantly increased corticospinal excitability when completed alone, but when it was primed by a practice block, no modulatory effects on corticospinal excitability were found. It is possible that sonification of combined action observation and motor imagery may not be a useful strategy to improve corticospinal, but further studies are needed to explore its relationship with performance improvements. We also confirm the neuromodulatory effect of aPAS, but its interaction with audiomotor practice remain unclear.

Effect of 10 Weeks of Complex Training on Speed and Power in Academy Soccer Players.

PURPOSE: This study investigated the effects of complex-paired and reverse-contrast 10-week training programs on sprint, power, and change-of-direction speed performance of elite academy soccer players. METHODS: Seventeen elite academy soccer players each performed assessments of the 10- and 40-m sprint, Abalakov vertical jump, seated medicine-ball throw, and Arrowhead change-of-direction speed test, both prior to and after a twice-weekly 10-week resistance-training program. The participants were randomly split into 2 groups; the complex-paired training group (CPT, n = 9) performed 4 different complex pairs (heavy-resistance exercises paired with plyometric and Olympic lifting-style exercises), with each pair being interspersed with an 8-minute recovery period in line with recommended guidelines. The comparative group-the reverse-contrast training group (RCT, n = 8)-performed the same exercises; however, all of the plyometric and Olympic lifting exercises preceded the heavy-resistance exercises. RESULTS: Both groups achieved postintervention increases in the seated medicine-ball throw test (CPT +1.8% and RCT +1.6%, P < .05), whereas VJ performance improved only in the CPT group (+3.4%, P = .003). No significant improvements were observed in either the 10- and the 40-m sprint or Arrowhead change-of-direction speed test for either group. CONCLUSIONS: The CPT experienced a small but significant within-group improvement in jump performance. However, no significant between-groups differences were observed in any of the testing variables postintervention. Subsequently, for academy soccer athletes, the CPT approach did not produce meaningful benefits to performance compared with a more time-efficient reverse-contrast approach.

Integrating explicit contextual priors and kinematic information during anticipation.

We examined the interaction between explicit contextual priors and kinematic information during anticipation in soccer. We employed a video-based anticipation task where skilled soccer players had to predict the direction of the imminent actions of an attacking opponent in possession of the ball. The players performed the task both with and without explicit contextual priors pertaining to the opponent's action tendencies. The strength of the opponent's action tendencies was altered in order to manipulate the reliability of contextual priors (low vs. high). Moreover, the reliability of kinematic information (low vs. high) was manipulated using the temporal occlusion paradigm. The explicit provision of contextual priors biased anticipation towards the most likely direction, given the opponent's action tendencies, and resulted in enhanced performance. This effect was greater under conditions where the reliability of kinematic information was low rather than high. When the reliability of kinematic information was high, the players used explicit contextual priors of high, but not low, reliability to inform their judgements. Findings suggest that athletes employ reliability-based strategies when integrating contextual priors with kinematic information during anticipation. The impact of explicit contextual priors is dependent on the reliability both of the priors and the evolving kinematic information.

Seven centuries of reconstructed Brahmaputra River discharge demonstrate underestimated high discharge and flood hazard frequency.

The lower Brahmaputra River in Bangladesh and Northeast India often floods during the monsoon season, with catastrophic consequences for people throughout the region. While most climate models predict an intensified monsoon and increase in flood risk with warming, robust baseline estimates of natural climate variability in the basin are limited by the short observational record. Here we use a new seven-century (1309-2004 C.E) tree-ring reconstruction of monsoon season Brahmaputra discharge to demonstrate that the early instrumental period (1956-1986 C.E.) ranks amongst the driest of the past seven centuries (13th percentile). Further, flood hazard inferred from the recurrence frequency of high discharge years is severely underestimated by 24-38% in the instrumental record compared to previous centuries and climate model projections. A focus on only recent observations will therefore be insufficient to accurately characterise flood hazard risk in the region, both in the context of natural variability and climate change.

The impact of task load on the integration of explicit contextual priors and visual information during anticipation.

There is limited knowledge about the impact of task load on experts' integration of contextual priors and visual information during dynamic and rapidly evolving anticipation tasks. We examined how experts integrate contextual priors--specifically, prior information regarding an opponent's action tendencies--with visual information such as movement kinematics, during a soccer-specific anticipation task. Furthermore, we combined psychophysiological measures and retrospective self-reports to gain insight into the cognitive load associated with this integration. Players were required to predict the action of an oncoming opponent, with and without the explicit provision of contextual priors, under two different task loads. In addition to anticipation performance, we compared continuous electroencephalography (EEG) and self-reports of cognitive load across conditions. Our data provide tentative evidence that increased task load may impair performance by disrupting the integration of contextual priors and visual information. EEG data suggest that cognitive load may increase when contextual priors are explicitly provided, whereas self-report data suggested a decrease in cognitive load. The findings provide insight into the processing demands associated with integration of contextual priors and visual information during dynamic anticipation tasks, and have implications for the utility of priors under cognitively demanding conditions. Furthermore, our findings add to the existing literature, suggesting that continuous EEG may be a more valid measure than retrospective self-reports for in-task assessment of cognitive load.

Dynamic task observation: A gaze-mediated complement to traditional action observation treatment?

Action observation elicits changes in primary motor cortex known as motor resonance, a phenomenon thought to underpin several functions, including our ability to understand and imitate others' actions. Motor resonance is modulated not only by the observer's motor expertise, but also their gaze behaviour. The aim of the present study was to investigate motor resonance and eye movements during observation of a dynamic goal-directed action, relative to an everyday one - a reach-grasp-lift (RGL) action, commonly used in action-observation-based neurorehabilitation protocols. Skilled and novice golfers watched videos of a golf swing and an RGL action as we recorded MEPs from three forearm muscles; gaze behaviour was concurrently monitored. Corticospinal excitability increased during golf swing observation, but it was not modulated by expertise, relative to baseline; no such changes were observed for the RGL task. MEP amplitudes were related to participants' gaze behaviour: in the RGL condition, target viewing was associated with lower MEP amplitudes; in the golf condition, MEP amplitudes were positively correlated with time spent looking at the effector or neighbouring regions. Viewing of a dynamic action such as the golf swing may enhance action observation treatment, especially when concurrent physical practice is not possible.

The impact of contextual priors and anxiety on performance effectiveness and processing efficiency in anticipation.

It is proposed that experts are able to integrate prior contextual knowledge with emergent visual information to make complex predictive judgments about the world around them, often under heightened levels of uncertainty and extreme time constraints. However, limited knowledge exists about the impact of anxiety on the use of such contextual priors when forming our decisions. We provide a novel insight into the combined impact of contextual priors and anxiety on anticipation in soccer. Altogether, 12 expert soccer players were required to predict the actions of an oncoming opponent while viewing life-sized video simulations of 2-versus-2 defensive scenarios. Performance effectiveness and processing efficiency were measured under four conditions: no contextual priors (CP) about the action tendencies of the opponent and low anxiety (LA); no CP and high anxiety (HA); CP and LA; CP and HA. The provision of contextual priors did not affect processing efficiency, but it improved performance effectiveness on congruent trials. Anxiety negatively affected processing efficiency, but this did not affect the use of contextual priors or influence performance effectiveness. It appears that anxiety and prior contextual information impact attentional resources independent of each other. Findings are discussed with reference to current models of anticipation and anxiety.

Size-growth asymmetry is not consistently related to productivity across an eastern US temperate forest network.

Modeling and forecasting forests as carbon sinks require that we understand the primary factors affecting productivity. One factor thought to be positively related to stand productivity is the degree of asymmetry, or the slope of the relationship between tree size and biomass growth. Steeper slopes indicate disproportionate productivity of big trees relative to small trees. Theoretically, big trees outcompete smaller trees during favorable growth conditions because they maintain better access to light. For this reason, high productivity forests are expected to have asymmetric growth. However, empirical studies do not consistently support this expectation, and those that do are limited in spatial or temporal scope. Here, we analyze size-growth relationships from 1970 to 2011 across a diverse network of forest sites in the eastern United States (n = 16) to test whether asymmetry is consistently related to productivity. To investigate this relationship, we analyze asymmetry-productivity relationships between our 16 forests at non-overlapping annual, 2-, 5-, 10-, and 20-year sampling intervals and find that asymmetry is negatively related to productivity, but the strength depends on the specific interval considered. Within-site temporal variability in asymmetry and productivity are generally positively correlated over time, except at the 5-year remeasurement interval. Rather than confirming or failing to support a positive relationship between asymmetry and productivity, our findings suggest caution interpreting these metrics since the relationship varies across forest types and temporal scales.

Experts integrate explicit contextual priors and environmental information to improve anticipation efficiency.

The understanding of how experts integrate prior situation-specific information (i.e., contextual priors) with emergent visual information when performing dynamic and temporally constrained tasks is limited. We used a soccer-based anticipation task to examine the ability of expert and novice players to integrate prior information about an opponent's action tendencies with unfolding environmental information such as opponent kinematics. We recorded gaze behaviors and ongoing expectations during task performance. Moreover, we assessed their final anticipatory judgments and perceived levels of cognitive effort invested. Explicit contextual priors biased the allocation of visual attention and shaped ongoing expectations in experts but not in novices. When the final action was congruent with the most likely action given the opponent's action tendencies, the contextual priors enhanced the final judgments for both groups. For incongruent trials, the explicit priors had a negative impact on the final judgments of novices but not experts. We interpreted the data using a Bayesian framework to provide novel insights into how contextual priors and dynamic environmental information are combined when making decisions under time pressure. Moreover, we provide evidence that this integration is governed by the temporal relevance of the information at hand as well as the ability to infer this relevance. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Cerebral effects of music during isometric exercise: An fMRI study.

A block-design experiment was conducted using fMRI to examine the brain regions that activate during the execution of an isometric handgrip exercise performed at light-to-moderate-intensity in the presence of music. Nineteen healthy adults (7 women and 12 men; Mage = 24.2, SD = 4.9 years) were exposed to an experimental condition (music [MU]) and a no-music control condition (CO) in a randomized order within a single session. Each condition lasted for 10 min and participants were required to execute 30 exercise trials (i.e., 1 trial = 10 s exercise + 10 s rest). Attention allocation, exertional responses, and affective changes were assessed immediately after each condition. The BOLD response was compared between conditions to identify the combined effects of music and exercise on neural activity. The findings indicate that music reallocated attention toward task-unrelated thoughts (d = 0.52) and upregulated affective arousal (d = 0.72) to a greater degree when compared to a no-music condition. The activity of the left inferior frontal gyrus (lIFG) also increased when participants executed the motor task in the presence of music (F = 24.65), and a significant negative correlation was identified between lIFG activity and perceived exertion for MU (limb discomfort: r = -0.54; overall exertion: r = -0.62). The authors hypothesize that the lIFG activates in response to motor tasks that are executed in the presence of environmental sensory stimuli. Activation of this region might also moderate processing of interoceptive signals - a neurophysiological mechanism responsible for reducing exercise consciousness and ameliorating fatigue-related symptoms.

Drought timing and local climate determine the sensitivity of eastern temperate forests to drought.

Projected changes in temperature and drought regime are likely to reduce carbon (C) storage in forests, thereby amplifying rates of climate change. While such reductions are often presumed to be greatest in semi-arid forests that experience widespread tree mortality, the consequences of drought may also be important in temperate mesic forests of Eastern North America (ENA) if tree growth is significantly curtailed by drought. Investigations of the environmental conditions that determine drought sensitivity are critically needed to accurately predict ecosystem feedbacks to climate change. We matched site factors with the growth responses to drought of 10,753 trees across mesic forests of ENA, representing 24 species and 346 stands, to determine the broad-scale drivers of drought sensitivity for the dominant trees in ENA. Here we show that two factors-the timing of drought, and the atmospheric demand for water (i.e., local potential evapotranspiration; PET)-are stronger drivers of drought sensitivity than soil and stand characteristics. Drought-induced reductions in tree growth were greatest when the droughts occurred during early-season peaks in radial growth, especially for trees growing in the warmest, driest regions (i.e., highest PET). Further, mean species trait values (rooting depth and ψ50 ) were poor predictors of drought sensitivity, as intraspecific variation in sensitivity was equal to or greater than interspecific variation in 17 of 24 species. From a general circulation model ensemble, we find that future increases in early-season PET may exacerbate these effects, and potentially offset gains in C uptake and storage in ENA owing to other global change factors.

Investigating the causes of increased 20th-century fall precipitation over the southeastern United States.

Much of the eastern United States (US) experienced increased precipitation over the 20th century. Characterizing these trends and their causes is critical for assessing future hydroclimate risks. Here, US precipitation trends are analyzed during 1895-2016, revealing that fall precipitation in the southeastern region north of the Gulf of Mexico (SE-Gulf) increased by nearly 40%, primarily increasing after the mid-1900s. As fall is the climatological dry season in the SE-Gulf and precipitation in other seasons changed insignificantly, the seasonal precipitation cycle diminished substantially. The increase in SE-Gulf fall precipitation was caused by increased southerly moisture transport from the Gulf of Mexico, which was almost entirely driven by stronger winds associated with enhanced anticyclonic circulation west of the North Atlantic Subtropical High (NASH) and not by increases in specific humidity. Atmospheric models forced by observed SSTs and fully-coupled models forced by historical anthropogenic forcing do not robustly simulate 20th-century fall wetting in the SE-Gulf. SST-forced atmospheric models do simulate an intensified anticyclonic low-level circulation around the NASH, but the modeled intensification occurred farther west than observed. CMIP5 analyses suggest an increased likelihood of positive SE-Gulf fall precipitation trends given historical and future GHG forcing. Nevertheless, individual model simulations (both SST-forced and fully-coupled) only very rarely produce the observed magnitude of the SE-Gulf fall precipitation trend. Further research into model representation of the western ridge of the fall NASH is needed, which will help us better predict whether 20th-century increases in SE-Gulf fall precipitation will persist into the future.