Wave Breaking Dissipation in a Young Wind Sea

2014 ◽  
Vol 44 (1) ◽  
pp. 104-127 ◽  
Author(s):  
Michael Schwendeman ◽  
Jim Thomson ◽  
Johannes R. Gemmrich
Keyword(s):  
Wind Waves ◽  
Phase Speed ◽  
Field Studies ◽  
Turbulent Energy ◽  
Strength Parameter ◽  
Video Recordings ◽  
Sonar System ◽  
Wind Sea ◽  
Equilibrium Range

Abstract Coupled in situ and remote sensing measurements of young, strongly forced wind waves are applied to assess the role of breaking in an evolving wave field. In situ measurements of turbulent energy dissipation from wave-following Surface Wave Instrument Float with Tracking (SWIFT) drifters and a tethered acoustic Doppler sonar system are consistent with wave evolution and wind input (as estimated using the radiative transfer equation). The Phillips breaking crest distribution Λ(c) is calculated using stabilized shipboard video recordings and the Fourier-based method of Thomson and Jessup, with minor modifications. The resulting Λ(c) are unimodal distributions centered around half of the phase speed of the dominant waves, consistent with several recent studies. Breaking rates from Λ(c) increase with slope, similar to in situ dissipation. However, comparison of the breaking rate estimates from the shipboard video recordings with the SWIFT video recordings show that the breaking rate is likely underestimated in the shipboard video when wave conditions are calmer and breaking crests are small. The breaking strength parameter b is calculated by comparison of the fifth moment of Λ(c) with the measured dissipation rates. Neglecting recordings with inconsistent breaking rates, the resulting b data do not display any clear trends and are in the range of other reported values. The Λ(c) distributions are compared with the Phillips equilibrium range prediction and previous laboratory and field studies, leading to the identification of several inconsistencies.

Post-Hurricane Michael damage assessment using ADCIRC storm surge hindcast, image classification, and LiDAR

Shore & Beach ◽  
2019 ◽  
pp. 3-14 ◽  
Author(s):  
Joshua Davis ◽  
Diana Mitsova ◽  
Tynon Briggs ◽  
Tiffany Briggs
Keyword(s):  
Wave Energy ◽  
Field Studies ◽  
Feedback Mechanism ◽  
Water Velocity ◽  
Airborne Lidar ◽  
Storm Events ◽  
Magnetic Current ◽  
Coastal Mapping ◽  
Electro Magnetic

Wave forcing from hurricanes, nor’easters, and energetic storms can cause erosion of the berm and beach face resulting in increased vulnerability of dunes and coastal infrastructure. LIDAR or other surveying techniques have quantified post-event morphology, but there is a lack of in situ hydrodynamic and morphodynamic measurements during extreme storm events. Two field studies were conducted in March 2018 and April 2019 at Bethany Beach, Delaware, where in situ hydrodynamic and morphodynamic measurements were made during a nor’easter (Nor’easter Riley) and an energetic storm (Easter Eve Storm). An array of sensors to measure water velocity, water depth, water elevation and bed elevation were mounted to scaffold pipes and deployed in a single cross-shore transect. Water velocity was measured using an electro-magnetic current meter while water and bed elevations were measured using an acoustic distance meter along with an algorithm to differentiate between the water and bed during swash processes. GPS profiles of the beach face were measured during every day-time low tide throughout the storm events. Both accretion and erosion were measured at different cross-shore positions and at different times during the storm events. Morphodynamic change along the back-beach was found to be related to berm erosion, suggesting an important morphologic feedback mechanism. Accumulated wave energy and wave energy flux per unit area between Nor’easter Riley and a recent mid-Atlantic hurricane (Hurricane Dorian) were calculated and compared. Coastal Observations: JALBTCX/NCMP emergency-response airborne Lidar coastal mapping & quick response data products for 2016/2017/2018 hurricane impact assessments

Coliform transport in a pristine reservoir: modeling and field studies

1998 ◽  
Vol 37 (2) ◽  
pp. 137-144 ◽  
Author(s):  
Elisa Garvey ◽  
John E. Tobiason ◽  
Michael Hayes ◽  
Evelyn Wolfram ◽  
David A. Reckhow ◽  
...  
Keyword(s):  
Model Development ◽  
Fate And Transport ◽  
Field Studies ◽  
Meteorological Conditions ◽  
Reservoir Modeling ◽  
Vertical Circulation ◽  
Quality Model ◽  
Circulation Patterns ◽  
In Situ Experiments

This paper reports on field studies and model development aimed at understanding coliform fate and transport in the Quabbin Reservoir, an oligotrophic drinking water supply reservoir. An investigation of reservoir currents suggested the importance of wind driven phenomena, and that both lateral and vertical circulation patterns exist. In-situ experiments of coliform decay suggested dependence on light intensity and yielded an appropriate decay coefficient to be used in CE-QUAL-W2, a two-dimensional hydrodynamic and water quality model. Modeling confirmed the sensitivity of reservoir outlet concentration to vertical variability within the reservoir, meteorological conditions, and location of coliform source.

Real-life Field Studies of the NOx Removing Properties of Photocatalytic Surfaces in Roskilde and Copenhagen Airport, Denmark

2020 ◽  
Vol 01 ◽  
Author(s):  
Henrik Jensen ◽  
Pernille D. Pedersen
Keyword(s):  
Air Quality ◽  
High Stability ◽  
Reference Site ◽  
Real Life ◽  
Field Studies ◽  
The Real ◽  
Before And After ◽  
Parking Lot ◽  
Photocatalytic Concrete

Aims: To evaluate the real-life effect of photocatalytic surfaces on the air quality at two test-sites in Denmark. Background: Poor air quality is today one of the largest environmental issues, due to the adverse effects on human health associated with high levels of air pollution, including respiratory issues, cardiovascular disease (CVD), and lung cancer. NOx removal by TiO2 based photocatalysis is a tool to improve air quality locally in areas where people are exposed. Methods: Two test sites were constructed in Roskilde and Copenhage airport. In Roskilde, the existing asphalt at two parking lots was treated with TiO2 containing liquid and an in-situ ISO 22197-1 test setup was developed to enable in-situ evaluation of the activity of the asphalt. In CPH airport, photocatalytic concrete tiles were installed at the "kiss and fly" parking lot, and NOx levels were continuously monitored in 0.5 m by CLD at the active site and a comparable reference site before and after installation for a period of 2 years. Results: The Roskilde showed high stability of the photocatalytic coating with the activity being largely unchanged over a period of 2 years. The CPH airport study showed that the average NOx levels were decreased by 12 % comparing the before and after NOx concentrations at the active and reference site. Conclusion: The joined results of the two Danish demonstration projects illustrate a high stability of the photocatalytic coating as well as a high potential for improvements of the real-life air quality in polluted areas.

scholarly journals Pelagic deep-sea fauna observed on video transects in the southern Norwegian Sea

Polar Biology ◽  
2021 ◽  
Author(s):  
Philipp Neitzel ◽  
Aino Hosia ◽  
Uwe Piatkowski ◽  
Henk-Jan Hoving
Keyword(s):  
First Record ◽  
Observation System ◽  
In Situ Observation ◽  
Norwegian Sea ◽  
Video Recordings ◽  
In Situ Observations ◽  
Abundance And Distribution ◽  
Oceanic Food Webs ◽  
Deep Sea Fauna

AbstractObservations of the diversity, distribution and abundance of pelagic fauna are absent for many ocean regions in the Atlantic, but baseline data are required to detect changes in communities as a result of climate change. Gelatinous fauna are increasingly recognized as vital players in oceanic food webs, but sampling these delicate organisms in nets is challenging. Underwater (in situ) observations have provided unprecedented insights into mesopelagic communities in particular for abundance and distribution of gelatinous fauna. In September 2018, we performed horizontal video transects (50–1200 m) using the pelagic in situ observation system during a research cruise in the southern Norwegian Sea. Annotation of the video recordings resulted in 12 abundant and 7 rare taxa. Chaetognaths, the trachymedusaAglantha digitaleand appendicularians were the three most abundant taxa. The high numbers of fishes and crustaceans in the upper 100 m was likely the result of vertical migration. Gelatinous zooplankton included ctenophores (lobate ctenophores,Beroespp.,Euplokamissp., and an undescribed cydippid) as well as calycophoran and physonect siphonophores. We discuss the distributions of these fauna, some of which represent the first record for the Norwegian Sea.

Sampling and Reconstructing User Experience

2013 ◽  
pp. 225-245
Author(s):  
Panos Markopoulos ◽  
Vassilis-Javed Khan
Keyword(s):  
Experience Sampling ◽  
Field Studies ◽  
Reconstruction Method ◽  
Working Parents ◽  
Diary Method ◽  
User Attitudes ◽  
Communication Needs ◽  
Sampling And Reconstruction

The Experience Sampling and Reconstruction Method (ESRM) is a research method suitable for user studies conducted in situ that is needed for the design and evaluation of ambient intelligence technologies. ESRM is a diary method supported by a distributed application, Reconexp, which runs on a mobile device and a website, enabling surveying user attitudes, experiences, and requirements in field studies. ESRM combines aspects of the Experience Sampling Method and the Day Reconstruction Method aiming to reduce data loss, improve data quality, and reduce burden put upon participants. The authors present a case study of using this method in the context of a study of communication needs of working parents with young children. Requirements for future developments of the tool and the method are discussed.

scholarly journals Physical changes within a large tropical hydroelectric reservoir induced by wintertime cold front activity

2014 ◽  
Vol 18 (8) ◽  
pp. 3079-3093 ◽  
Author(s):  
M. P. Curtarelli ◽  
E. H. Alcântara ◽  
C. D. Rennó ◽  
J. L. Stech
Keyword(s):  
Weather Forecasting ◽  
Cold Front ◽  
Three Dimensional ◽  
Remote Sensing Data ◽  
Turbulent Energy ◽  
Heat Fluxes ◽  
Physical Processes ◽  
Tropical Reservoir ◽  
The Difference

Abstract. We investigated the influence of wintertime cold front activity on the physical processes within a large tropical reservoir located in Brazil. The period chosen for this study consisted of 49 days between 28 April 2010 and 15 July 2010. This period was defined based on information from the Brazilian Center for Weather Forecasting and Climate Studies (CPTEC), data collected in situ and the interpretation of remotely sensed images. To better understand the governing processes that drive changes in the heat balance, differential cooling and mixing dynamics, a simulation was performed that utilized a three-dimensional hydrodynamic model enforced with in situ and remote sensing data. The results showed that during a cold front passage over the reservoir, the sensible and latent heat fluxes were enhanced by approximately 77 and 16%, respectively. The reservoir's daily averaged heat loss was up to 167% higher on the days with cold front activity than on the days without activity. The cold front passage also intensified the differential cooling process; in some cases the difference between the water temperature of the littoral and pelagic zones reached up to 8 °C. The occurrence of cold front passages impacted the diurnal mixed layer (DML), by increasing the turbulent energy input (∼54%) and the DML depth (∼41%). Our results indicate that the cold front events are one of the main meteorological disturbances driving the physical processes within hydroelectric reservoirs located in tropical South America during the wintertime. Hence, cold front activity over these aquatic systems has several implications for water quality and reservoir management in Brazil.

scholarly journals Moulding the ideal crab: implications of phenotypic plasticity for crustacean stock enhancement

2020 ◽  
Author(s):  
Benjamin J Daly ◽  
Ginny L Eckert ◽  
W Christopher Long
Keyword(s):  
Phenotypic Plasticity ◽  
Large Scale ◽  
Field Studies ◽  
Stock Enhancement ◽  
Adaptive Responses ◽  
Ecological Performance ◽  
Significant Research ◽  
Morphological Differences ◽  
Plastic Responses

Abstract Numerous examples of behavioural and morphological differences between hatchery-cultured and wild individuals exist for a range of crustacean species; however, we submit that these variances are not deficiencies, but rather are adaptive responses to an unnatural rearing environment that may be detrimental in the natural environment. This phenotypic plasticity could be beneficial for stock enhancement because such plasticity suggests potential for change with adjustments to rearing protocols to achieve improved ecological competence. We examine how specific plastic responses can affect crustacean ecology through effects on predation, foraging, competition, and reproduction. For developing stock enhancement programmes, we recommend consideration of plastic phenotypic patterns before large-scale releases are initiated. Researchers can identify environmental factors that cue plasticity during hatchery rearing, determine if induced responses are ecologically influential after release into the wild, and examine the temporal scale on which phenotypic plasticity operates. Communal hatchery rearing at low-to-medium stocking densities with predator cues and natural substrates along with in situ conditioning, releases during periods of low predation risk, and coupled laboratory-field studies can contribute to improved ecological performance during stock enhancement. Finally, presentation of non-significant research results is needed to avoid bias towards hatchery–wild differences and help guide future conditioning programmes.

Field Studies of Features of Wind Waves at Short Fetches

2018 ◽  
Vol 82 (11) ◽  
pp. 1431-1434 ◽  
Author(s):  
G. A. Baydakov ◽  
A. A. Kandaurov ◽  
A. M. Kuznetsova ◽  
D. A. Sergeev ◽  
Yu. I. Troitskaya
Keyword(s):  
Wind Waves ◽  
Field Studies

scholarly journals PROCEDURES TO MEASURE MEAN AMBIENT DOSE EQUIVALENT RATES USING ELECTRET ION CHAMBERS

2020 ◽  
Vol 190 (1) ◽  
pp. 6-21
Author(s):  
F Leontaris ◽  
A Boziari ◽  
A Clouvas ◽  
M Kolovou ◽  
J Guilhot
Keyword(s):  
Gamma Spectrometry ◽  
Voltage Drop ◽  
Field Studies ◽  
Dose Equivalent ◽  
Ionization Chambers ◽  
Ambient Dose Equivalent ◽  
The Mean ◽  
Ion Chambers ◽  
Ambient Dose

Abstract The capabilities of electret ion chambers (EICs) to measure mean ambient dose equivalent rates were investigated by performing both laboratory and field studies of their properties. First, EICs were ‘calibrated’ to measure ambient gamma dose equivalent in the Ionizing Calibration Laboratory of the Greek Atomic Energy Commission. The EICs were irradiated with different gamma photon energies and from different angles. Calibration factors were deduced (electret’s voltage drop due to irradiation in terms of ambient dose equivalent). In the field studies, EICs were installed at eight locations belonging to the Greek Early Warning System Network (which is based on Reuter-Stokes ionization chambers) for three periods, averaging 5 months each. In the same locations, in situ gamma spectrometry measurements were performed with portable germanium detectors. Gamma ambient dose equivalent rates were deduced by the in situ gamma spectrometry measurements and by soil sample analysis. The mean daily electret potential drop (in Volts) was compared with the mean daily ambient dose equivalent, measured with a portable HPGe detector and Reuter-Stokes high-pressure ionization chambers. From these measurements, ‘field’ calibration factors (electret’s voltage drop due to gamma radiation in terms of ambient dose equivalent) were deduced and found in very good agreement with the values deduced in Laboratory. The influence of cosmic radiation and the intrinsic voltage loss when performing long-term environmental gamma measurements with EICs, was estimated.

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