scholarly journals Continental-Scale Increase in Lake and Stream Phosphorus: Are Oligotrophic Systems Disappearing in the United States?

2016 ◽  
Vol 50 (7) ◽  
pp. 3409-3415 ◽  
Author(s):  
John L. Stoddard ◽  
John Van Sickle ◽  
Alan T. Herlihy ◽  
Janice Brahney ◽  
Steven Paulsen ◽  
...  
Keyword(s):  
United States ◽  
The United States ◽  
Continental Scale

scholarly journals La collaboration scientifique et technologique en Amérique du Nord : un point de vue Canadien

2005 ◽  
Vol 24 (2) ◽  
pp. 269-296
Author(s):  
Charles H. David ◽  
Paul Dufour ◽  
Janet Halliwell
Keyword(s):  
United States ◽  
Open Economy ◽  
North American ◽  
Small Open Economy ◽  
Innovation System ◽  
The United States ◽  
Technology And Innovation ◽  
Continental Scale ◽  
Science Technology ◽  
Science Technology And Innovation

Canada, as a country with a small, open economy, faces the immediate challenge of learning to shape dynamic comparative advantage in the emerging international economy. About 75 % of Canada's trade linkages are with the United States, and a very large component of the Canadian experience of « globalization » is driven by North American economic integration. This integration is taking place in the absence of institutions and policy mechanisms to promote and manage science, technology, and innovation relations on a continental scale. Bilateral s & T arrangements centered on the United States presently characterize the North American innovation System. Circumstances in North America pose three sets of challenges to Canadian s & T policy. 1) Science and technology are increasing in importance in international trade, environmental, and social/cultural matters. This means that Canada must learn to improve its management of an increasingly internationalized domestic s & T System. 2) Canada must cultivate mutually beneficial bilateral s & T relationships with its two partners in NAFTA, Mexico and the United States. 3) Canada must identify where its interests lie in the development and governance of trilateral and international rules and arrangements for science, technology, and innovation.

scholarly journals The Impact of Movements and Animal Density on Continental Scale Cattle Disease Outbreaks in the United States

PLoS ONE ◽  
2014 ◽  
Vol 9 (3) ◽  
pp. e91724 ◽  
Author(s):  
Michael G. Buhnerkempe ◽  
Michael J. Tildesley ◽  
Tom Lindström ◽  
Daniel A. Grear ◽  
Katie Portacci ◽  
...  
Keyword(s):  
United States ◽  
Disease Outbreaks ◽  
The United States ◽  
Continental Scale ◽  
Cattle Disease ◽  
Animal Density ◽  
The Impact

scholarly journals A continental system for forecasting bird migration

Science ◽  
2018 ◽  
Vol 361 (6407) ◽  
pp. 1115-1118 ◽  
Author(s):  
Benjamin M. Van Doren ◽  
Kyle G. Horton
Keyword(s):  
United States ◽  
Bird Migration ◽  
The United States ◽  
Atmospheric Conditions ◽  
The Public ◽  
Continental Scale ◽  
Seasonal Migrations ◽  
Migration Intensity ◽  
And Performance ◽  
Migratory Movements

Billions of animals cross the globe each year during seasonal migrations, but efforts to monitor them are hampered by the unpredictability of their movements. We developed a bird migration forecast system at a continental scale by leveraging 23 years of spring observations to identify associations between atmospheric conditions and bird migration intensity. Our models explained up to 81% of variation in migration intensity across the United States at altitudes of 0 to 3000 meters, and performance remained high in forecasting events 1 to 7 days in advance (62 to 76% of variation was explained). Avian migratory movements across the United States likely exceed 500 million individuals per night during peak passage. Bird migration forecasts will reduce collisions with buildings, airplanes, and wind turbines; inform a variety of monitoring efforts; and engage the public.

scholarly journals Estimating Snow Water Equivalent Using Snow Depth Data and Climate Classes

2010 ◽  
Vol 11 (6) ◽  
pp. 1380-1394 ◽  
Author(s):  
Matthew Sturm ◽  
Brian Taras ◽  
Glen E. Liston ◽  
Chris Derksen ◽  
Tobias Jonas ◽  
...  
Keyword(s):  
United States ◽  
Bulk Density ◽  
Snow Depth ◽  
Snow Water Equivalent ◽  
Estimation Procedure ◽  
The United States ◽  
Practical Applications ◽  
Continental Scale ◽  
Depth Data ◽  
Snow Water

Abstract In many practical applications snow depth is known, but snow water equivalent (SWE) is needed as well. Measuring SWE takes ∼20 times as long as measuring depth, which in part is why depth measurements outnumber SWE measurements worldwide. Here a method of estimating snow bulk density is presented and then used to convert snow depth to SWE. The method is grounded in the fact that depth varies over a range that is many times greater than that of bulk density. Consequently, estimates derived from measured depths and modeled densities generally fall close to measured values of SWE. Knowledge of snow climate classes is used to improve the accuracy of the estimation procedure. A statistical model based on a Bayesian analysis of a set of 25 688 depth–density–SWE data collected in the United States, Canada, and Switzerland takes snow depth, day of the year, and the climate class of snow at a selected location from which it produces a local bulk density estimate. When converted to SWE and tested against two continental-scale datasets, 90% of the computed SWE values fell within ±8 cm of the measured values, with most estimates falling much closer.

scholarly journals Automated Water Level Monitoring at the Continental Scale from ICESat-2 Photons

2021 ◽  
Vol 13 (18) ◽  
pp. 3631
Author(s):  
Austin Madson ◽  
Yongwei Sheng
Keyword(s):  
United States ◽  
Water Level ◽  
Cluster Computing ◽  
Mean Squared Error ◽  
The United States ◽  
United States Geological Survey ◽  
Continental Scale ◽  
Water Level Changes ◽  
Lakes And Reservoirs ◽  
The Mean

Of the approximately 6700 lakes and reservoirs larger than 1 km2 in the Contiguous United States (CONUS), only ~430 (~6%) are actively gaged by the United States Geological Survey (USGS) or their partners and are available for download through the National Water Information System database. Remote sensing analysis provides a means to fill in these data gaps in order to glean a better understanding of the spatiotemporal water level changes across the CONUS. This study takes advantage of two-plus years of NASA’s ICESat-2 (IS-2) ATLAS photon data (ATL03 products) in order to derive water level changes for ~6200 overlapping lakes and reservoirs (>1 km2) in the CONUS. Interactive visualizations of large spatial datasets are becoming more commonplace as data volumes for new Earth observing sensors have markedly increased in recent years. We present such a visualization created from an automated cluster computing workflow that utilizes tens of billions of ATLAS photons which derives water level changes for all of the overlapping lakes and reservoirs in the CONUS. Furthermore, users of this interactive website can download segmented and clustered IS-2 ATL03 photons for each individual waterbody so that they may run their own analysis. We examine ~19,000 IS-2 derived water level changes that are spatially and temporally coincident with water level changes from USGS gages and find high agreement with our results as compared to the in situ gage data. The mean squared error (MSE) and the mean absolute error (MAE) between these two products are 1 cm and 6 cm, respectively.

Continental scale variation in 17 O-excess of meteoric waters in the United States

2015 ◽  
Vol 164 ◽  
pp. 110-126 ◽  
Author(s):  
Shuning Li ◽  
Naomi E. Levin ◽  
Lesley A. Chesson
Keyword(s):  
United States ◽  
The United States ◽  
Continental Scale ◽  
Scale Variation

Continental-scale patterns in soil geochemistry and mineralogy: Results from two transects across the United States and Canada

2009 ◽  
Vol 24 (8) ◽  
pp. 1369-1381 ◽  
Author(s):  
Laurel G. Woodruff ◽  
William F. Cannon ◽  
Dennis D. Eberl ◽  
David B. Smith ◽  
James E. Kilburn ◽  
...  
Keyword(s):  
United States ◽  
The United States ◽  
Soil Geochemistry ◽  
Continental Scale ◽  
Soil Geochemistry And Mineralogy

scholarly journals Characterizing leaf area index (LAI) and vertical foliage profile (VFP) over the United States

2016 ◽  
Vol 13 (1) ◽  
pp. 239-252 ◽  
Author(s):  
H. Tang ◽  
S. Ganguly ◽  
G. Zhang ◽  
M. A. Hofton ◽  
R. F. Nelson ◽  
...  
Keyword(s):  
United States ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Canopy Structure ◽  
The United States ◽  
Data Set ◽  
Area Index ◽  
Continental Scale ◽  
Comparison Results ◽  
Waveform Lidar

Abstract. Leaf area index (LAI) and vertical foliage profile (VFP) are among the important canopy structural variables. Recent advances in lidar remote sensing technology have demonstrated the capability of accurately mapping LAI and VFP over large areas. The primary objective of this study was to derive and validate a LAI and VFP product over the contiguous United States (CONUS) using spaceborne waveform lidar data. This product was derived at the footprint level from the Geoscience Laser Altimeter System (GLAS) using a biophysical model. We validated GLAS-derived LAI and VFP across major forest biomes using airborne waveform lidar. The comparison results showed that GLAS retrievals of total LAI were generally accurate with little bias (r2 =  0.67, bias  =  −0.13, RMSE  =  0.75). The derivations of GLAS retrievals of VFP within layers were not as accurate overall (r2 =  0.36, bias  =  −0.04, RMSE  =  0.26), and these varied as a function of height, increasing from understory to overstory – 0 to 5 m layer: r2 =  0.04, bias  =  0.09, RMSE  =  0.31; 10 to 15 m layer: r2 =  0.53, bias  =  −0.08, RMSE  =  0.22; and 15 to 20 m layer: r2 =  0.66, bias  =  −0.05, RMSE  =  0.20. Significant relationships were also found between GLAS LAI products and different environmental factors, in particular elevation and annual precipitation. In summary, our results provide a unique insight into vertical canopy structure distribution across North American ecosystems. This data set is a first step towards a baseline of canopy structure needed for evaluating climate and land use induced forest changes at the continental scale in the future, and should help deepen our understanding of the role of vertical canopy structure in terrestrial ecosystem processes across varying scales.

scholarly journals Linking agricultural crop management and air quality models for regional to national-scale nitrogen assessments

2012 ◽  
Vol 9 (10) ◽  
pp. 4023-4035 ◽  
Author(s):  
E. J. Cooter ◽  
J. O. Bash ◽  
V. Benson ◽  
L. Ran
Keyword(s):  
United States ◽  
Air Quality ◽  
Ambient Air ◽  
The United States ◽  
Fertilizer Application ◽  
Nitrogen Fertilizers ◽  
System Level ◽  
Agricultural Crop ◽  
Modeling Framework ◽  
Continental Scale

Abstract. While nitrogen (N) is an essential element for life, human population growth and demands for energy, transportation and food can lead to excess nitrogen in the environment. A modeling framework is described and implemented to promote a more integrated, process-based and system-level approach to the estimation of ammonia (NH3) emissions which result from the application of inorganic nitrogen fertilizers to agricultural soils in the United States. The United States Department of Agriculture (USDA) Environmental Policy Integrated Climate (EPIC) model is used to simulate plant demand-driven fertilizer applications to commercial cropland throughout the continental US. This information is coupled with a process-based air quality model to produce continental-scale NH3 emission estimates. Regional cropland NH3 emissions are driven by the timing and amount of inorganic NH3 fertilizer applied, soil processes, local meteorology, and ambient air concentrations. Initial fertilizer application often occurs when crops are planted. A state-level evaluation of EPIC-simulated, cumulative planted area compares well with similar USDA reported estimates. EPIC-annual, inorganic fertilizer application amounts also agree well with reported spatial patterns produced by others, but domain-wide the EPIC values are biased about 6% low. Preliminary application of the integrated fertilizer application and air quality modeling system produces a modified geospatial pattern of seasonal NH3 emissions that improves current simulations of observed atmospheric particle nitrate concentrations. This modeling framework provides a more dynamic, flexible, and spatially and temporally resolved estimate of NH3 emissions than previous factor-based NH3 inventories, and will facilitate evaluation of alternative nitrogen and air quality policy and adaptation strategies associated with future climate and land use changes.

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