Integrating Regional Frameworks and Local Variability for Riverine Bioassessment

2021 ◽  
Author(s):  
Colby D. Denison ◽  
Mark C. Scott ◽  
Kevin M. Kubach ◽  
Brandon K. Peoples
Keyword(s):  
Local Variability

scholarly journals Modeling Low Intensity Fires: Lessons Learned from 2012 RxCADRE

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 139
Author(s):  
Rodman R. Linn ◽  
Judith L. Winterkamp ◽  
James H. Furman ◽  
Brett Williams ◽  
J. Kevin Hiers ◽  
...  
Keyword(s):  
Prescribed Fire ◽  
Fire Spread ◽  
Lessons Learned ◽  
Field Sampling ◽  
Wind Fields ◽  
Low Intensity ◽  
Novel Method ◽  
Wind Input ◽  
Variable Wind ◽  
Local Variability

Coupled fire-atmosphere models are increasingly being used to study low-intensity fires, such as those that are used in prescribed fire applications. Thus, the need arises to evaluate these models for their ability to accurately represent fire spread in marginal burning conditions. In this study, wind and fuel data collected during the Prescribed Fire Combustion and Atmospheric Dynamics Research Experiments (RxCADRE) fire campaign were used to generate initial and boundary conditions for coupled fire-atmosphere simulations. We present a novel method to obtain fuels representation at the model grid scale using a combination of imagery, machine learning, and field sampling. Several methods to generate wind input conditions for the model from eight different anemometer measurements are explored. We find a strong sensitivity of fire outcomes to wind inputs. This result highlights the critical need to include variable wind fields as inputs in modeling marginal fire conditions. This work highlights the complexities of comparing physics-based model results against observations, which are more acute in marginal burning conditions, where stronger sensitivities to local variability in wind and fuels drive fire outcomes.

Effect of Lateral Pipe-Soil Interaction on Controlled Lateral Buckling Using Pre-Deformed Pipeline

2018 ◽  
Author(s):  
Jayden Chee ◽  
Alastair Walker ◽  
David White
Keyword(s):  
High Temperature ◽  
Longitudinal Strain ◽  
Flow Line ◽  
Soft Clay ◽  
Axial Stiffness ◽  
Lateral Buckling ◽  
Novel Approach ◽  
Different Response ◽  
Local Variability ◽  
Very High

A novel approach to eliminate the onset of global buckling in pipelines is investigated in the paper. The method is based on pre-deforming a pipeline continuously with a specific wavelength and amplitude prior to installation on the seabed. The response of the pipeline to applied high temperature and pressure was studied in conjunction with variations in the lateral pipe-soil interaction (PSI) — both as uniform friction along the pipe and also with locally varying friction. Pipe and seabed parameters representing a typical wet-insulated infield flow line on soft clay are used. The pre-deformed pipeline has a higher buckle initiation temperature compared to a straight pipeline due to the reduced effective axial force build-up resulting from the low axial stiffness generated by the pre-deformed lobes along the pipeline. The results from this paper show that the strains in the pre-deformed pipeline are not significantly affected by the local variability of lateral PSI but rather by the global mean PSI. At a typical lateral soil resistance, i.e. a friction coefficient of 0.5, lateral buckling occurs at a very high temperature level that is not common in the subsea operation. At a very low friction, i.e. 0.1, lateral buckling occurs at a lower operating temperature but the strain is insignificant. The longitudinal strain of the pipeline is not highly sensitive to the lateral PSI, which is a quite different response to an initially straight pipeline. Therefore, this method could prove to be a valuable tool for the subsea industry as it enables the pipeline to be installed and operated safely at very high temperatures without the need for lateral buckling design and installation of expensive structures as buckle initiators. Even if the pre-deformed pipeline buckles at a very high temperature, during cycles of heat-up and cool-down the buckle shape ‘shakes down’ by geometric rearrangement to minimize the energy, and in doing so creates a series of ‘short pipelines’ in which the longitudinal strain is self-controlled. The system is therefore shown to be very robust in the conditions investigated and not affected by one of the biggest unknowns in seabed pipeline engineering, which is the local variability in lateral PSI.

scholarly journals Present temperature, precipitation and rain-on-snow climate in Svalbard

2020 ◽  
Author(s):  
Siiri Wickström ◽  
Marius O. Jonassen ◽  
John Cassano ◽  
Timo Vihma ◽  
Jørn Kristiansen
Keyword(s):  
Weather Prediction ◽  
Open Water ◽  
Low Pressure ◽  
Numerical Weather Prediction Model ◽  
The Arctic ◽  
Pressure Center ◽  
Climate Conditions ◽  
Temperature And Precipitation ◽  
Pressure Centre ◽  
Local Variability

<p>Potentially high-impact warm and wet winter conditions have become increasingly common in recent decades in the arctic archipelago of Svalbard. In this study, we document present 2m temperature, precipitation and rain-on-snow (ROS) climate conditions in Svalbard and relate them to different atmospheric circulation (AC) types. For this purpose, we utilise a set of observations together with output from the high resolution numerical weather prediction model AROME-Arctic. We find that 2m median temperatures vary the most across AC types in winter and spring, and the least in summer. Southerly and southwesterly flow is associated with 10th percentile 2m temperatures above freezing in all seasons. In terms of precipitation, we find the highest amounts and intensities with onshore flow over open water. Sea ice appears to play a strong role in the local variability in both 2m temperature and precipitation. ROS is a frequent phenomenon in the study period, in particular below 250 m ASL. In winter, ROS only occurs with AC types from the southerly sector or during the passage of a low pressure centre or trough. Most of these events occur during southwesterly flow, with a low pressure center west of Svalbard.</p><p> </p>

scholarly journals Local variability in growth and reproduction of Salix arctica in the High Arctic

2016 ◽  
Vol 35 (1) ◽  
pp. 24126 ◽  
Author(s):  
Noémie Boulanger-Lapointe ◽  
Esther Lévesque ◽  
Claudia Baittinger ◽  
Niels M. Schmidt
Keyword(s):  
High Arctic ◽  
Salix Arctica ◽  
Local Variability ◽  
Growth And Reproduction

Atmospheric influences and local variability of air pollution close to a motorway in an Alpine valley during winter

2008 ◽  
Vol 17 (3) ◽  
pp. 297-309 ◽  
Author(s):  
Klaus Schäfer ◽  
Johannes Vergeiner ◽  
Stefan Emeis ◽  
Julia Wittig ◽  
Maria Hoffmann ◽  
...  
Keyword(s):  
Air Pollution ◽  
Alpine Valley ◽  
Local Variability

scholarly journals Assessing ice margin fluctuations on differing timescales: Chronological constraints from Sermeq Kujatdleq and Nordenskiöld Gletscher, central West Greenland

The Holocene ◽  
2018 ◽  
Vol 28 (7) ◽  
pp. 1160-1172 ◽  
Author(s):  
Samuel E Kelley ◽  
Jason P Briner ◽  
Sandy L O’Hara
Keyword(s):  
Late Holocene ◽  
Sediment Cores ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ice Dynamics ◽  
West Greenland ◽  
Southern Site ◽  
Ice Velocity ◽  
Observational Record ◽  
Local Variability

The observational record of ice margin position reveals asynchrony in both the timing and magnitude of Greenland Ice Sheet (GrIS) margin fluctuations and illustrates the complex reactions of ice sheets to climatic perturbations. In this study, we reconstruct the timing and pattern of middle- and late-Holocene GrIS margin fluctuations at two locations, ~190 km apart, in central West Greenland using radiocarbon-dated sediment cores from proglacial-threshold lakes. Our results demonstrate that deglaciation occurs at both sites during the early Holocene, with the ice sheet remaining in a smaller-than-present ice margin configuration until ~500 years ago when it readvanced into lake catchments at both sites. At our northern site, Sermeq Kujatdleq, the late-Holocene advance of the GrIS approached maximum position during the past 280 years, with the culmination of the advance occurring at AD 1992–1994, and modern retreat was underway by AD 1998–2001. In contrast, field and observational evidence suggest that the GrIS at our southern site, Nordenskiöld Gletscher, has been advancing or stable throughout the 20th century. These results, in conjunction with previous work in the region, highlight the asynchronous nature of late-Holocene advances and subsequent modern retreat, implying that local variability, such as ice velocity or ice dynamics, is responsible for modulating ice margin response to changes in climate on these decadal to centennial timescales. Additional high-resolution records of past ice sheet fluctuations are needed to inform and more accurately constrain our predictions of future cryosphere response to changes in climate.

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