scholarly journals Spatially coherent regional changes in seasonal extreme streamflow events in the United States and Canada since 1950

2020 ◽  
Vol 6 (49) ◽  
pp. eaba5939
Author(s):  
Evan N. Dethier ◽  
Shannon L. Sartain ◽  
Carl E. Renshaw ◽  
Francis J. Magilligan

Complex hydroclimate in the United States and Canada has limited identification of possible ongoing changes in streamflow. We address this challenge by classifying 541 stations in the United States and Canada into 15 “hydro-regions,” each with similar seasonal streamflow characteristics. Analysis of seasonal streamflow records at these stations from 1910 to present indicates regionally coherent changes in the frequency of extreme high- and low-flow events. Where changes are significant, these events have, on average, doubled in frequency relative to 1950 to 1969. In hydro-regions influenced by snowmelt runoff, extreme high-flow event frequency has increased despite snowpack depletion by warming winter temperatures. In drought-prone hydro-regions of the western United States and Southeast, extreme low-flow event frequency has increased, particularly during summer and fall. The magnitude and regional consistency of these hydrologic changes warrant attention by watershed stakeholders. The hydro-region framework facilitates quantification and further analyses of these changes to extreme streamflow.

2015 ◽  
Vol 43 (7) ◽  
pp. 1181-1192 ◽  
Author(s):  
Ling Wang ◽  
Chia-Wen Lee ◽  
Timothy Mantz ◽  
Huang-Chia Hung

We explored the effect of racing advergames on player perception of brand personality and investigated the roles of flow and self-construal in this effect. Participants were 202 male students at colleges in the United States and Taiwan, and they completed pretest and posttest scales relating to their feeling and attitude toward brands before and after playing the racing advergame. The results showed that, when playing advergames, flow and self-construal interacted to influence perception of brand personality. Gamers experiencing high flow during the game provided positive feedback on brand personality, whereas gamers experiencing low flow provided negative feedback. Gamers with an interdependent self-construal reported higher scores for evaluation of brand personality after playing advergames than did gamers with an independent self-construal.


Author(s):  
Jennifer J. Smith

Coherence of place often exists alongside irregularities in time in cycles, and chapter three turns to cycles linked by temporal markers. Ray Bradbury’s The Martian Chronicles (1950) follows a linear chronology and describes the exploration, conquest, and repopulation of Mars by humans. Conversely, Louise Erdrich’s Love Medicine (1984) jumps back and forth across time to narrate the lives of interconnected families in the western United States. Bradbury’s cycle invokes a confluence of historical forces—time as value-laden, work as a calling, and travel as necessitating standardized time—and contextualizes them in relation to anxieties about the space race. Erdrich’s cycle invokes broader, oppositional conceptions of time—as recursive and arbitrary and as causal and meaningful—to depict time as implicated in an entire system of measurement that made possible the destruction and exploitation of the Chippewa people. Both volumes understand the United States to be preoccupied with imperialist impulses. Even as they critique such projects, they also point to the tenacity with which individuals encounter these systems, and they do so by creating “interstitial temporalities,” which allow them to navigate time at the crossroads of language and culture.


Author(s):  
Kathryn T Duncan ◽  
Meriam N Saleh ◽  
Kellee D Sundstrom ◽  
Susan E Little

Abstract Throughout North America, Dermacentor spp. ticks are often found feeding on animals and humans, and are known to transmit pathogens, including the Rocky Mountain spotted fever agent. To better define the identity and distribution of Dermacentor spp. removed from dogs and cats in the United States, ticks submitted from 1,457 dogs (n = 2,924 ticks) and 137 cats (n = 209 ticks) from veterinary practices in 44/50 states from February 2018-January 2020 were identified morphologically (n = 3,133); the identity of ticks from regions where Dermacentor andersoni (Stiles) have been reported, and a subset of ticks from other regions, were confirmed molecularly through amplification and sequencing of the ITS2 region and a 16S rRNA gene fragment. Of the ticks submitted, 99.3% (3,112/3,133) were Dermacentor variabilis (Say), 0.4% (12/3,133) were D. andersoni, and 0.3% (9/3,133) were Dermacentor albipictus (Packard). While translocation of pets prior to tick removal cannot be discounted, the majority (106/122; 87%) of Dermacentor spp. ticks removed from dogs and cats in six Rocky Mountain states (Montana, Idaho, Wyoming, Nevada, Utah, and Colorado) were D. variabilis, suggesting this species may be more widespread in the western United States than is currently recognized, or that D. andersoni, if still common in the region, preferentially feeds on hosts other than dogs and cats. Together, these data support the interpretation that D. variabilis is the predominant Dermacentor species found on pets throughout the United States, a finding that may reflect recent shifts in tick distribution.


2014 ◽  
Vol 53 (6) ◽  
pp. 1578-1592 ◽  
Author(s):  
Nina S. Oakley ◽  
Kelly T. Redmond

AbstractThe northeastern Pacific Ocean is a preferential location for the formation of closed low pressure systems. These slow-moving, quasi-barotropic systems influence vertical stability and sustain a moist environment, giving them the potential to produce or affect sustained precipitation episodes along the west coast of the United States. They can remain motionless or change direction and speed more than once and thus often pose difficult forecast challenges. This study creates an objective climatological description of 500-hPa closed lows to assess their impacts on precipitation in the western United States and to explore interannual variability and preferred tracks. Geopotential height at 500 hPa from the NCEP–NCAR global reanalysis dataset was used at 6-h and 2.5° × 2.5° resolution for the period 1948–2011. Closed lows displayed seasonality and preferential durations. Time series for seasonal and annual event counts were found to exhibit strong interannual variability. Composites of the tracks of landfalling closed lows revealed preferential tracks as the features move inland over the western United States. Correlations of seasonal event totals for closed lows with ENSO indices, the Pacific decadal oscillation (PDO), and the Pacific–North American (PNA) pattern suggested an above-average number of events during the warm phase of ENSO and positive PDO and PNA phases. Precipitation at 30 U.S. Cooperative Observer stations was attributed to closed-low events, suggesting 20%–60% of annual precipitation along the West Coast may be associated with closed lows.


1993 ◽  
Vol 14 (4) ◽  
pp. 148-151
Author(s):  
Debra H. Fiser

Definition Drowning is defined as death caused by submersion, whereas near-drowning connotes survival for some time period following submersion. The following remarks pertain to the near-drowning victim who presents for acute medical management. Epidemiology Because reporting of near-drowning incidents is incomplete, most of the available epidemiologic information focuses on drowning deaths, which number more than 6500 per year in the United States. Data from King County, Washington, however, suggest that near-drownings slightly out-number drownings. Drowning rates are highest for children under the age of 5 years and between the ages of 15 and 24 years. Males drown 4 times more frequently than females. African-Americans and low-income groups also are affected disproportionately, except for those drownings involving boats and residential swimming pools, which more often are owned by middle class groups. Drownings peak during the summer months and are most common in the southern and western United States and Alaska. Forty to 45% of all drownings occur while the victim is swimming and 12% to 29% are boat-related. Alcohol plays a substantial role in these deaths. Between one half and three quarters of all drownings occur in lakes, ponds, rivers, and the ocean. More than 40% of all submersions in these bodies of water involve older adolescents or young adults.


2018 ◽  
Vol 19 (5) ◽  
pp. 803-814 ◽  
Author(s):  
Gregory J. McCabe ◽  
David M. Wolock ◽  
Melissa Valentin

Abstract Winter snowfall and accumulation is an important component of the surface water supply in the western United States. In these areas, increasing winter temperatures T associated with global warming can influence the amount of winter precipitation P that falls as snow S. In this study we examine long-term trends in the fraction of winter P that falls as S (Sfrac) for 175 hydrologic units (HUs) in snow-covered areas of the western United States for the period 1951–2014. Because S is a substantial contributor to runoff R across most of the western United States, we also examine long-term trends in water-year runoff efficiency [computed as water-year R/water-year P (Reff)] for the same 175 HUs. In that most S records are short in length, we use model-simulated S and R from a monthly water balance model. Results for Sfrac indicate long-term negative trends for most of the 175 HUs, with negative trends for 139 (~79%) of the HUs being statistically significant at a 95% confidence level (p = 0.05). Additionally, results indicate that the long-term negative trends in Sfrac have been largely driven by increases in T. In contrast, time series of Reff for the 175 HUs indicate a mix of positive and negative long-term trends, with few trends being statistically significant (at p = 0.05). Although there has been a notable shift in the timing of R to earlier in the year for most HUs, there have not been substantial decreases in water-year R for the 175 HUs.


1980 ◽  
Vol 70 (2) ◽  
pp. 487-508
Author(s):  
Sonja Faber ◽  
Gerhard MÜller

abstract Precursors to S and SKS were observed in long-period SRO and WWSSN seismograms of the Romanian earthquake of March 4, 1977, recorded in the United States at distances from 68° to 93°. According to the fault-plane solution, the stations were close to a nodal plane and SV radiation was optimum in their direction. Particle-motion diagrams, constructed from the digital data of the SRO station ANMO (distance 89.1°), show the P-wave character of the precursors. Several interpretations are discussed; the most plausible is that the precursors are Sp phases generated by conversion from S to P below the station. The travel-time differences between S or SKS and Sp are about 60 sec and indicate conversion in the transition zone between the upper and lower mantle. Sp conversions were also observed at long-period WWSSN stations in the western United States for 2 Tonga-Fiji deep-focus earthquakes (distances from 82° to 96°). Special emphasis is given in this paper to the calculation of theoretical seismograms, both for Sp precursors and the P-wave coda, including high-order multiples such as sP4 which may arrive simultaneously with Sp. The Sp calculations show: (1) the conversions produced by S, ScS, and SKS at interfaces or transition zones between the upper and lower mantle form a complicated interference pattern, and (2) conversion at transition zones is less effective than at first-order discontinuities only if their thickness is greater than about half a wavelength of S waves. As a consequence, details of the velocity structure between the upper and lower mantle can only be determined within these limits from long-period Sp observations. Our observations are compatible with velocity models having pronounced transition zones at depths of 400 and 670 km as have been proposed for the western United States, and they exclude much smoother structures. Our study suggests that long-period Sp precursors from pure thrust or normal-fault earthquakes, observed at distances from 70° to 95° close to a nodal plane and at azimuths roughly perpendicular to its strike, offer a simple means for qualitative mapping of the sharpness of the transition zones between the upper and lower mantle.


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