scholarly journals Measuring Subaqueous Progradation of the Wax Lake Delta with a Model of Flow Direction Divergence

2018 ◽  
Author(s):  
John B. Shaw ◽  
Justin D. Estep ◽  
Amanda R. Whaling ◽  
Kelly M. Sanks ◽  
Douglas A. Edmonds
Keyword(s):  
Flow Direction ◽  
Remote Sensing Data ◽  
Remotely Sensed ◽  
Diagnostic Signature ◽  
Wax Lake Delta ◽  
Coastal Louisiana ◽  
Changes Over Time ◽  
Direction Field ◽  
Over Time ◽  
Distributary Channel

Abstract. Remotely sensed flow patterns can reveal the location of the subaqueous distal tip of a distributary channel on a prograding river delta. Morphodynamic feedbacks produce distributary channel tips that become shallower over their final reaches before becoming deeper over the unchannelized foreset. The flow direction field over this morphology tends to diverge and then converge providing a diagnostic signature that can be captured in flow or remote sensing data. Twenty-one measurements from the Wax Lake Delta (WLD) in coastal Louisiana, and 317 measurements from numerically simulated deltas show that the transition from divergence to convergence occurs in a distribution that is centered just downstream of the channel tip, on average 132 m in the case of the WLD. With these data we validate the Flow Direction to Channel tips (FD2C) inverse model for remotely estimating subaqueous channel tip location. We apply this model to 33 remotely sensed images of the WLD between its initiation in 1974 and 2016. We find that the distributaries grew unevenly, 6 of the primary channels grew at rates of 60–80 m/yr while one grew at 116 m/yr. We also estimate the growth rate of the total area enclosed by the subaqueous delta platform to be 1.83 km2/yr with no obvious rate changes over time.

scholarly journals Measuring subaqueous progradation of the Wax Lake Delta with a model of flow direction divergence

2018 ◽  
Vol 6 (4) ◽  
pp. 1155-1168 ◽  
Author(s):  
John B. Shaw ◽  
Justin D. Estep ◽  
Amanda R. Whaling ◽  
Kelly M. Sanks ◽  
Douglas A. Edmonds
Keyword(s):  
Remote Sensing ◽  
Flow Direction ◽  
Remote Sensing Data ◽  
Land Area ◽  
Constant Rate ◽  
Diagnostic Signature ◽  
Wax Lake Delta ◽  
Coastal Louisiana ◽  
Direction Field ◽  
Distributary Channel

Abstract. Remotely sensed flow patterns can reveal the location of the subaqueous distal tip of a distributary channel on a prograding river delta. Morphodynamic feedbacks produce distributary channels that become shallower over their final reaches before the unchannelized foreset slopes basinward. The flow direction field over this morphology tends to diverge and then converge, providing a diagnostic signature that can be captured in flow or remote sensing data. A total of 21 measurements from the Wax Lake Delta (WLD) in coastal Louisiana and 317 measurements from numerically simulated deltas show that the transition from divergence to convergence occurs in a distribution that is centered just downstream of the channel tip, on average 132 m in the case of the WLD. These data validate an inverse model for remotely estimating subaqueous channel tip location. We apply this model to 33 images of the WLD between its initiation in 1974 and 2016. We find that six of the primary channels grew at rates of 60–80 m yr−1, while the remaining channel grew at 116 m yr−1. We also show that the subaqueous delta planform grew at a constant rate (1.72 km2 yr−1). Subaerial land area initially grew at the same rate but slowed after about 1999. We explain this behavior as a gradual decoupling of channel tip progradation and island aggradation that may be common in maturing deltas.

Protected area design and monitoring

2010 ◽  
Author(s):  
Ned Horning ◽  
Julie A. Robinson ◽  
Eleanor J. Sterling ◽  
Woody Turner ◽  
Sacha Spector
Keyword(s):  
National Parks ◽  
Protected Area ◽  
Remotely Sensed ◽  
Heritage Sites ◽  
Envisat Asar ◽  
Space Agency ◽  
National Boundaries ◽  
Set Up ◽  
Changes Over Time ◽  
Over Time

Researchers interested in remote locations have developed monitoring schemes, sometimes called “Watchful Eye” monitoring, that use a time series of remotely sensed images to assess changes over time to a protected area or habitat. For instance, the European Space Agency (ESA) and UNESCO have set up repeat analyses of satellite imagery for World Heritage sites. The first area for which they developed this technique was the habitat of the critically endangered mountain gorilla (Gorilla berengei berengei) in the Virunga Mountains in Central Africa, including the Bwindi and Mgahinga National Parks in Uganda, the Virunga and Kahuzi-Biega National Parks in the Democratic Republic of Congo, and the trans-boundary Volcanoes Conservation Area. The project developed detailed maps of these inaccessible zones so that protected area managers can monitor the gorilla habitat. Previously, available maps were old and inaccurate (at times handmade), did not completely cover the range of the gorillas, and did not cross national boundaries. Because there was no systematic information from the ground regarding changes over time, researchers also used remotely sensed data to complete change detection analyses over the past two decades. Using both optical (Landsat series) and radar (ENVISAT ASAR) satellite data, researchers were able to quantify rates of deforestation between 1990 and 2003 and relate these rates to human migration rates into the area resulting from regional political instability. Researchers constructed the first digital base maps of the areas, digital elevation models (DEMs), and updated vegetation and land use maps. They faced significant problems in both field and laboratory activities, including lack of existing ground data, dense vegetation cover, and fairly continuous cloud cover. They therefore used a combination of ESA ENVISAT ASAR as well as Landsat and ESA Medium Resolution Imaging Spectrometer (MERIS) optical data. The radar images allowed them to quantify elevation and distances between trees and homes. Landsat and MERIS data helped identify forest cover types, with Landsat providing finer-scale images at less frequent intervals and MERIS serving lower-resolution images more frequently.

scholarly journals Comparative Quality and Trend of Remotely Sensed Phenology and Productivity Metrics across the Western United States

2020 ◽  
Vol 12 (16) ◽  
pp. 2538
Author(s):  
Ethan E. Berman ◽  
Tabitha A. Graves ◽  
Nate L. Mikle ◽  
Jerod A. Merkle ◽  
Aaron N. Johnston ◽  
...  
Keyword(s):  
United States ◽  
Remote Sensing ◽  
Growing Season ◽  
Remotely Sensed ◽  
Deciduous Forests ◽  
Western United States ◽  
Instantaneous Rate ◽  
Near Surface ◽  
Changes Over Time ◽  
Over Time

Vegetation phenology and productivity play a crucial role in surface energy balance, plant and animal distribution, and animal movement and habitat use and can be measured with remote sensing metrics including start of season (SOS), peak instantaneous rate of green-up date (PIRGd), peak of season (POS), end of season (EOS), and integrated vegetation indices. However, for most metrics, we do not yet understand the agreement of remotely sensed data products with near-surface observations. We also need summaries of changes over time, spatial distribution, variability, and consistency in remote sensing dataset metrics for vegetation timing and quality. We compare metrics from 10 leading remote sensing datasets against a network of PhenoCam near-surface cameras throughout the western United States from 2002 to 2014. Most phenology metrics representing a date (SOS, PIRGd, POS, and EOS), rather than a duration (length of spring, length of growing season), better agreed with near-surface metrics but results varied by dataset, metric, and land cover, with absolute value of mean bias ranging from 0.38 (PIRGd) to 37.92 days (EOS). Datasets had higher agreement with PhenoCam metrics in shrublands, grasslands, and deciduous forests than in evergreen forests. Phenology metrics had higher agreement than productivity metrics, aside from a few datasets in deciduous forests. Using two datasets covering the period 1982–2016 that best agreed with PhenoCam metrics, we analyzed changes over time to growing seasons. Both datasets exhibited substantial spatial heterogeneity in the direction of phenology trends. Variability of metrics increased over time in some areas, particularly in the Southwest. Approximately 60% of pixels had consistent trend direction between datasets for SOS, POS, and EOS, with the direction varying by location. In all ecoregions except Mediterranean California, EOS has become later. This study comprehensively compares remote sensing datasets across multiple growing season metrics and discusses considerations for applied users to inform their data choices.

Comparison of two devices for measuring exercise transcutaneous oxygen pressures in patients with claudication

VASA ◽  
2015 ◽  
Vol 44 (5) ◽  
pp. 355-362 ◽  
Author(s):  
Marie Urban ◽  
Alban Fouasson-Chailloux ◽  
Isabelle Signolet ◽  
Christophe Colas Ribas ◽  
Mathieu Feuilloy ◽  
...  
Keyword(s):  
Oxygen Pressure ◽  
Optical Sensors ◽  
Chemical Sensors ◽  
Transcutaneous Oxygen ◽  
Starting Values ◽  
Two Systems ◽  
Transcutaneous Oxygen Pressure ◽  
New Sensors ◽  
Changes Over Time ◽  
Over Time

Abstract. Summary: Background: We aimed at estimating the agreement between the Medicap® (photo-optical) and Radiometer® (electro-chemical) sensors during exercise transcutaneous oxygen pressure (tcpO2) tests. Our hypothesis was that although absolute starting values (tcpO2rest: mean over 2 minutes) might be different, tcpO2-changes over time and the minimal value of the decrease from rest of oxygen pressure (DROPmin) results at exercise shall be concordant between the two systems. Patients and methods: Forty seven patients with arterial claudication (65 + / - 7 years) performed a treadmill test with 5 probes each of the electro-chemical and photo-optical devices simultaneously, one of each system on the chest, on each buttock and on each calf. Results: Seventeen Medicap® probes disconnected during the tests. tcpO2rest and DROPmin values were higher with Medicap® than with Radiometer®, by 13.7 + / - 17.1 mm Hg and 3.4 + / - 11.7 mm Hg, respectively. Despite the differences in absolute starting values, changes over time were similar between the two systems. The concordance between the two systems was approximately 70 % for classification of test results from DROPmin. Conclusions: Photo-optical sensors are promising alternatives to electro-chemical sensors for exercise oximetry, provided that miniaturisation and weight reduction of the new sensors are possible.

Neuropsychological Symptoms in Posttraumatic Stress Disorder and Changes Over Time

2007 ◽  
Author(s):  
Miranda Olff ◽  
Mirjam Nijdam ◽  
Kristin Samuelson ◽  
Julia Golier ◽  
Mariel Meewisse ◽  
...  
Keyword(s):  
Posttraumatic Stress Disorder ◽  
Posttraumatic Stress ◽  
Stress Disorder ◽  
Neuropsychological Symptoms ◽  
Changes Over Time ◽  
Over Time

Changes Over Time in Adaptive Behavior Functioning of Twice-Exceptional Children

2010 ◽  
Author(s):  
Rebecca D. Stinson ◽  
Zachary Sussman ◽  
Megan Foley Nicpon ◽  
Allison L. Allmon ◽  
Courtney Cornick ◽  
...  
Keyword(s):  
Adaptive Behavior ◽  
Exceptional Children ◽  
Twice Exceptional ◽  
Changes Over Time ◽  
Over Time

Kategorisierung der Schädelform des Cavalier King Charles Spaniels

2019 ◽  
Vol 47 (02) ◽  
pp. 133-133
Keyword(s):  
Pilot Study ◽  
Cavalier King Charles Spaniel ◽  
Conformation Changes ◽  
Veterinary Record ◽  
Changes Over Time ◽  
Over Time

Knowler SP, Gillstedt L, Mitchell TJ et al. Pilot study of head conformation changes over time in the Cavalier King Charles spaniel breed. Veterinary Record 2019. doi:10.1136/vr.105135.

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