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Stream Classification Story Map
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Funded Projects
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Stream Classification System for the Appalachian Landscape Conservation Cooperative
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Stream Classification Story Map Image
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Image for the Stream Classification Story Map
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Strode 1891 Spoon River.pdf
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TRB Library
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STE-TAN
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Strode 1891 Thompsons Lake.pdf
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TRB Library
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STE-TAN
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Strode 1891.pdf
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TRB Library
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STE-TAN
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Strode Mussel Size.pdf
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TRB Library
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STE-TAN
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Stromgren 1975.pdf
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TRB Library
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STE-TAN
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Strong effect of dispersal network structure on ecological dynamics
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A central question in ecology with great importance for management, conservation and biological control is how changing connectivity affects the persistence and dynamics of interacting species. Researchers in many disciplines have used large systems of coupled oscillators to model the behaviour of a diverse array of fluctuating systems in nature1–4. In the well-studied regime of weak coupling, synchronization is favoured by increases in coupling strength and large-scale network structures (for example ‘small worlds’) that produce short cuts and clustering5–9. Here we show that, by contrast, randomizing the structure of dispersal networks in a model of predators and prey tends to favour asyn- chrony and prolonged transient dynamics, with resulting effects on the amplitudes of population fluctuations. Our results focus on synchronization and dynamics of clusters in models, and on time- scales, more appropriate for ecology, namely smaller systems with strong interactions outside the weak-coupling regime, rather than the better-studied cases of large, weakly coupled systems. In these smaller systems, the dynamics of transients and the effects of changes in connectivity can be well understood using a set of methods including numerical reconstructions of phase dynamics, examinations of cluster formation and the consideration of important aspects of cyclic dynamics, such as amplitude.
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Climate Science Documents
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Strong increase in convective precipitation in response to higher temperatures
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Precipitation changes can affect society more directly than variations in most other meteorological observables1–3, but precipitation is difficult to characterize because of fluctuations on nearly all temporal and spatial scales. In addition, the intensity of extreme precipitation rises markedly at higher temperature4–9, faster than the rate of increase in the atmosphere’s water-holding capacity1,4 , termed the Clausius– Clapeyron rate. Invigoration of convective precipitation (such as thunderstorms) has been favoured over a rise in stratiform precipitation (such as large-scale frontal precipitation) as a cause for this increase4,10, but the relative contributions of these two types of precipitation have been difficult to disentan- gle. Here we combine large data sets from radar measurements and rain gauges over Germany with corresponding synoptic ob- servations and temperature records, and separate convective and stratiform precipitation events by cloud observations. We find that for stratiform precipitation, extremes increase with temperature at approximately the Clausius–Clapeyron rate, without characteristic scales. In contrast, convective precipi- tation exhibits characteristic spatial and temporal scales, and its intensity in response to warming exceeds the Clausius– Clapeyron rate. We conclude that convective precipitation responds much more sensitively to temperature increases than stratiform precipitation, and increasingly dominates events of extreme precipitation.
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Climate Science Documents
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Stronger winds over a large lake in response to weakening air-to-lake temperature gradient
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The impacts of climate change on the world’s large lakes are a cause for concern1–4. For example, over the past decades, mean surface water temperatures in Lake Superior, North America, have warmed faster than air temperature during the thermally stratified summer season, because decreasing ice cover has led to increased heat input2,5. However, the effects of this change on large lakes have not been studied extensively6. Here we analyse observations from buoys and satellites as well as model reanalyses for Lake Superior, and find that increasing temperatures in both air and surface water, and a reduction in the temperature gradient between air and water are destabilizing the atmospheric surface layer above the lake. As a result, surface wind speeds above the lake are increasing by nearly 5% per decade, exceeding trends in wind speed over land. A numerical model of the lake circulation suggests that the increasing wind speeds lead to increases in current speeds, and long-term warming causes the surface mixed layer to shoal and the season of stratification to lengthen. We conclude that climate change will profoundly affect the biogeochemical cycles of large lakes, the mesoscale atmospheric circulation at lake–land boundaries and the transport of airborne pollutants in regions that are rich in lakes.
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