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Статті в журналах з теми "Ocean prediction through observation"
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Byun, Do-Seong, and Deirdre E. Hart. "Predicting Tidal Currents Using 25-h Observations through a Complete Tidal Species Modulation with Tidal Current Constant Corrections Method." Journal of Atmospheric and Oceanic Technology 35, no. 12 (December 2018): 2405–20. http://dx.doi.org/10.1175/jtech-d-18-0120.1.
Повний текст джерелаАнотація:
AbstractA new approach enabling the prediction of tidal currents, for observation sites with as little as ≥25 h of data, has been developed as a practical way of utilizing very short tidal current records. We name this technique the complete tidal species modulation with tidal current constant corrections (CTSM+TCCC) method. In addition to a short-term tidal current record from the “observation site,” this technique also requires (i) ideally half a year (specifically, ≥183 days from any time) and (ii) concurrent (≥25 h) sea level observation records from a nearby “reference site.” The reliability of the CTSM+TCCC method is tested for three different tidal current regimes (almost rectilinear, elliptical, and near circular) in Geyonggi Bay, South Korea, using daily slices (25 h long) of 29-day tidal current records from each observation station, plus sea level records from the nearby Incheon reference station. RMSE analysis of the resulting prediction time series demonstrates that the CTSM+TCCC method produces reasonably accurate predictions based on observation station records derived from spring, but not neap, tide periods. We conclude that our method can be successfully employed to make tidal current predictions using 25-h observation station records obtained from spring tide periods, ideally gathered during periods of relatively calm weather. As well as testing the sensitivity of CTSM+TCCC predictions to observation record timing, the effect of reference station location was investigated using records from 20 stations spread along the South Korean coasts. Results revealed that tidal records from nearby tidal current observation and sea level reference stations produce reasonable current predictions, since proximal locations share similar tidal species’ modulated tidal and tidal current behaviors.
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Lenetsky, Jed E., Bruno Tremblay, Charles Brunette, and Gianluca Meneghello. "Subseasonal Predictability of Arctic Ocean Sea Ice Conditions: Bering Strait and Ekman-Driven Ocean Heat Transport." Journal of Climate 34, no. 11 (June 2021): 4449–62. http://dx.doi.org/10.1175/jcli-d-20-0544.1.
Повний текст джерелаАнотація:
AbstractWe use ocean observations and reanalyses to investigate the subseasonal predictability of summer and fall sea ice area (SIA) in the western Arctic Ocean associated with lateral ocean heat transport (OHT) through Bering Strait and vertical OHT along the Alaskan coastline from Ekman divergence and upwelling. Results show predictive skill of spring Bering Strait OHT anomalies in the Chukchi Sea and eastern East Siberian Sea for June and July SIA, followed by a sharp drop in predictive skill in August, September, and October and a resurgence of the correlation in November during freeze-up. Fall upwelling of Pacific Water along the Alaskan coastline—a mechanism that was proposed as a preconditioner for lower sea ice concentration (SIC) in the Beaufort Sea the following summer—shows minimal predictive strength on both local and regional scales for any months of the melt season. A statistical hindcast based on May Bering Strait OHT anomalies explains 77% of July Chukchi Sea SIA variance. Using OHT as a predictor of SIA anomalies in the Chukchi Sea improves hindcasts from the simple linear trend by 35% and predictions from spring sea ice thickness anomalies by 24%. This work highlights the importance of ocean heat anomalies for melt season sea ice prediction and provides observational evidence of subseasonal changes in forecast skill observed in model-based forecasts of the Chukchi Sea.
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Nichols, Charles Reid, and Lynn Donelson Wright. "The Evolution and Outcomes of a Collaborative Testbed for Predicting Coastal Threats." Journal of Marine Science and Engineering 8, no. 8 (August 16, 2020): 612. http://dx.doi.org/10.3390/jmse8080612.
Повний текст джерелаАнотація:
Beginning in 2003, the Southeastern Universities Research Association (SURA) enabled an open-access network of distributed sensors and linked computer models through the SURA Coastal Ocean Observing and Predicting (SCOOP) program. The goal was to support collaborations among universities, government, and industry to advance integrated observation and modeling systems. SCOOP improved the path to operational real-time data-guided predictions and forecasts of coastal ocean processes. This was critical to the maritime infrastructure of the U.S. and to the well-being of coastal communities. SCOOP integrated and expanded observations from the Gulf of Mexico, the South Atlantic Bight, the Middle Atlantic Bight, and the Chesapeake Bay. From these successes, a Coastal and Ocean Modeling Testbed (COMT) evolved with National Oceanic and Atmospheric Administration (NOAA) funding via the Integrated Ocean Observing System (IOOS) to facilitate the transition of key models from research to operations. Since 2010, COMT has been a conduit between the research community and the federal government for sharing and improving models and software tools. SCOOP and COMT have been based on strong partnerships among universities and U.S. agencies that have missions in ocean and coastal environmental prediction. During SURA’s COMT project, which ended September 2018, significant progress was made in evaluating the performance of models that are progressively becoming operational. COMT successes are ongoing.
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Storto, Andrea, Paolo Oddo, Elisa Cozzani, and Emanuel Ferreira Coelho. "Introducing Along-Track Error Correlations for Altimetry Data in a Regional Ocean Prediction System." Journal of Atmospheric and Oceanic Technology 36, no. 8 (August 2019): 1657–74. http://dx.doi.org/10.1175/jtech-d-18-0213.1.
Повний текст джерелаАнотація:
AbstractBecause of the systematic error in the processing of altimetry data, sea level anomaly (SLA) observation errors are likely affected by nonnegligible spatial correlations. To account for these, we exploit the synergy of altimetry data with in situ profiles from gliders, piloted to follow the altimetry tracks during the Long-Term Glider Mission for Environmental Characterization 2017 (LOGMEC17) observational campaign in the Ligurian Sea. The assimilation of along-track unfiltered sea level anomalies in a regional ocean analysis and forecast system is consequently optimized by means of introducing spatial correlations for the SLA observation errors. In particular, collocated data of glider and altimetry are used to derive an along-track error covariance model for the sea level anomaly assimilation, assuming that most of the covariance behavior versus separation distance stems from altimetry. Spatial scales of the altimetry error are found to have a correlation radius of about 12 km for the dataset utilized in the Ligurian Sea, using a simple Gaussian shape for the error correlation, shorter than the correlation radius found through assimilation output diagnostics. A variational data assimilation system is modified to relax the usual assumption of uncorrelated altimetry observation errors, thus allowing for along-track error correlations. Its implementation provides promising results in the regional ocean prediction system, outperforming in most verification skill scores the use of uncorrelated observational errors without compromising the analysis scheme efficiency.
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Kang, Minhyeop, Kyungnam Ko, and Minyeong Kim. "Verification of the Reliability of Offshore Wind Resource Prediction Using an Atmosphere–Ocean Coupled Model." Energies 13, no. 1 (January 3, 2020): 254. http://dx.doi.org/10.3390/en13010254.
Повний текст джерелаАнотація:
An atmosphere–ocean coupled model is proposed as an optimal numerical prediction method for the offshore wind resource. Meteorological prediction models are mainly used for wind speed prediction, with active studies using atmospheric models. Seawater mixing occurring at sea due to solar radiation and wind intensity can significantly change the sea surface temperature (SST), an important variable for predicting wind resources and energy production, considering its wind effect, within a short time. This study used the weather research forecasting and ocean mixed layer (WRF-OML) model, an atmosphere–ocean coupled model, to reflect time-dependent SST and sea surface fluxes. Results are compared with those of the WRF model, another atmospheric model, and verified through comparison with observation data of a meteorological mast (met-mast) at sea. At a height of 94 m, the wind speed predicted had a bias and root mean square error of 1.09 m/s and 2.88 m/s for the WRF model, and −0.07 m/s and 2.45 m/s for the WRF-OML model, respectively. Thus, the WRF-OML model has a higher reliability. In comparing to the met-mast observation data, the annual energy production (AEP) estimation based on the predicted wind speed showed an overestimation of 15.3% and underestimation of 5.9% from the WRF and WRF-OML models, respectively.
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Duerr, Alana E. S., Manhar R. Dhanak, and James H. Van Zwieten. "Utilizing the Hybrid Coordinate Ocean Model for the Assessment of Florida Current’s Hydrokinetic Renewable Energy Resource." Marine Technology Society Journal 46, no. 5 (September 1, 2012): 24–33. http://dx.doi.org/10.4031/mtsj.46.5.2.
Повний текст джерелаАнотація:
AbstractTraditionally, renewable energy resources have been assessed through collection and analysis of extensive in situ observations; however, in situ data collection can be cost and time prohibitive, especially for initial site selection and feasibility studies. Ocean models, such as the HYbrid Coordinate Ocean Model (HYCOM), provide corresponding data for resource assessment at a significantly lower cost, provided the models can be validated and appropriately corrected through comparison with some in situ observations. In this study, in situ velocity observations in the Florida Current are compared with the velocities predicted by the ocean model. Measured velocity profiles at the location of a moored ADCP have been compared with corresponding predictions from the HYCOM model. The data are used to evaluate the associated hydrokinetic energy and to estimate the energy resource using the HYCOM data and in situ observational data for comparison. In general, HYCOM predictions of the velocity and the corresponding energy resource in the Florida Current are lower than those suggested by the observational data. A method for addressing these apparent discrepancies is discussed and is shown to improve prediction of the resource assessment.
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Wu, Bo, Xiaolong Chen, Fengfei Song, Yong Sun, and Tianjun Zhou. "Initialized Decadal Predictions by LASG/IAP Climate System Model FGOALS-s2: Evaluations of Strengths and Weaknesses." Advances in Meteorology 2015 (2015): 1–12. http://dx.doi.org/10.1155/2015/904826.
Повний текст джерелаАнотація:
Decadal prediction experiments are conducted by using the coupled global climate model FGOALS-s2, following the CMIP 5 protocol. The paper documents the initialization procedures for the decadal prediction experiments and summarizes the predictive skills of the experiments, which are assessed through indicators adopted by the IPCC AR5. The observational anomalies of surface and subsurface ocean temperature and salinity are assimilated through a modified incremental analysis update (IAU) scheme. Three sets of 10-year-long hindcast and forecast runs were started every five years in the period of 1960–2005, with the initial conditions taken from the assimilation runs. The decadal prediction experiment by FGOALS-s2 shows significant high predictive skills in the Indian Ocean, tropical western Pacific, and Atlantic, similar to the results of the CMIP5 multimodel ensemble. The predictive skills in the Indian Ocean and tropical western Pacific are primarily attributed to the model response to the external radiative forcing associated with the change of atmospheric compositions. In contrast, the high skills in the Atlantic are attributed, at least partly, to the improvements in the prediction of the Atlantic multidecadal variability coming from the initialization.
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Smith, Gregory C., Yimin Liu, Mounir Benkiran, Kamel Chikhar, Dorina Surcel Colan, Audrey-Anne Gauthier, Charles-Emmanuel Testut, et al. "The Regional Ice Ocean Prediction System v2: a pan-Canadian ocean analysis system using an online tidal harmonic analysis." Geoscientific Model Development 14, no. 3 (March 15, 2021): 1445–67. http://dx.doi.org/10.5194/gmd-14-1445-2021.
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Abstract. Canada has the longest coastline in the world and includes diverse ocean environments, from the frozen waters of the Canadian Arctic Archipelago to the confluence region of Labrador and Gulf Stream waters on the east coast. There is a strong need for a pan-Canadian operational regional ocean prediction capacity covering all Canadian coastal areas in support of marine activities including emergency response, search and rescue, and safe navigation in ice-infested waters. Here we present the first pan-Canadian operational regional ocean analysis system developed as part of the Regional Ice Ocean Prediction System version 2 (RIOPSv2) running in operations at the Canadian Centre for Meteorological and Environmental Prediction (CCMEP). The RIOPSv2 domain extends from 26∘ N in the Atlantic Ocean through the Arctic Ocean to 44∘ N in the Pacific Ocean, with a model grid resolution that varies between 3 and 8 km. RIOPSv2 includes a multivariate data assimilation system based on a reduced-order extended Kalman filter together with a 3D-Var bias correction system for water mass properties. The analysis system assimilates satellite observations of sea level anomaly and sea surface temperature, as well as in situ temperature and salinity measurements. Background model error is specified in terms of seasonally varying model anomalies from a 10-year forced model integration, allowing inhomogeneous anisotropic multivariate error covariances. A novel online tidal harmonic analysis method is introduced that uses a sliding-window approach to reduce numerical costs and allow for the time-varying harmonic constants necessary in seasonally ice-infested waters. Compared to the Global Ice Ocean Prediction System (GIOPS) running at CCMEP, RIOPSv2 also includes a spatial filtering of model fields as part of the observation operator for sea surface temperature (SST). In addition to the tidal harmonic analysis, the observation operator for sea level anomaly (SLA) is also modified to remove the inverse barometer effect due to the application of atmospheric pressure forcing fields. RIOPSv2 is compared to GIOPS and shown to provide similar innovation statistics over a 3-year evaluation period. Specific improvements are found near the Gulf Stream for all model fields due to the higher model grid resolution, with smaller root mean squared (rms) innovations for RIOPSv2 of about 5 cm for SLA and 0.5 ∘C for SST. Verification against along-track satellite observations demonstrates the improved representation of mesoscale features in RIOPSv2 compared to GIOPS, with increased correlations of SLA (0.83 compared to 0.73) and reduced rms differences (12 cm compared to 14 cm). While the RIOPSv2 grid resolution is 3 times higher than GIOPS, the power spectral density of surface kinetic energy provides an indication that the effective resolution of RIOPSv2 is roughly double that of the global system (35 km compared to 66 km). Observations made as part of the Year of Polar Prediction (2017–2019) provide a rare glimpse at errors in Arctic water mass properties and show average salinity biases over the upper 500 m of 0.3–0.4 psu in the eastern Beaufort Sea in RIOPSv2.
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Zhang, Xuefeng, Shaoqing Zhang, Zhengyu Liu, Xinrong Wu, and Guijun Han. "Parameter Optimization in an Intermediate Coupled Climate Model with Biased Physics." Journal of Climate 28, no. 3 (February 1, 2015): 1227–47. http://dx.doi.org/10.1175/jcli-d-14-00348.1.
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Abstract Imperfect physical parameterization schemes in a coupled climate model are an important source of model biases that adversely impact climate prediction. However, how observational information should be used to optimize physical parameterizations through parameter estimation has not been fully studied. Using an intermediate coupled ocean–atmosphere model, the authors investigate parameter optimization when the assimilation model contains biased physics within a biased assimilation experiment framework. Here, the biased physics is induced by using different outgoing longwave radiation schemes in the assimilation model and the “truth” model that is used to generate simulated observations. While the stochastic physics, implemented by initially perturbing the physical parameters, can significantly enhance the ensemble spread and improve the representation of the model ensemble, the parameter estimation is able to mitigate the model biases induced by the biased physics. Furthermore, better results for climate estimation and prediction can be obtained when only the most influential physical parameters are optimized and allowed to vary geographically. In addition, the parameter optimization with the biased model physics improves the performance of the climate estimation and prediction in the deep ocean significantly, even if there is no direct observational constraint on the low-frequency component of the state variables. These results provide some insight into decadal predictions in a coupled ocean–atmosphere general circulation model that includes imperfect physical schemes that are initialized from the climate observing system.
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Vidard, A., D. L. T. Anderson, and M. Balmaseda. "Impact of Ocean Observation Systems on Ocean Analysis and Seasonal Forecasts." Monthly Weather Review 135, no. 2 (February 1, 2007): 409–29. http://dx.doi.org/10.1175/mwr3310.1.
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Abstract The relative merits of the Tropical Atmosphere–Ocean (TAO)/Triangle Trans-Ocean Buoy Network (TAO/TRITON) and Pilot Research Moored Array in the Tropical Atlantic mooring networks, the Voluntary Observing Ship (VOS) expendable bathythermograph (XBT) network, and the Argo float network are evaluated through their impact on ocean analyses and seasonal forecast skill. An ocean analysis is performed in which all available data are assimilated. In two additional experiments the moorings and the VOS datasets are withheld from the assimilation. To estimate the impact on seasonal forecast skill, the set of ocean analyses is then used to initialize a corresponding set of coupled ocean–atmosphere model forecasts. A further set of experiments is conducted to assess the impact of the more recent Argo array. A key parameter for seasonal forecast initialization is the depth of the thermocline in the tropical Pacific. This depth is quite similar in all of the experiments that involve data assimilation, but withdrawing the TAO data has a bigger effect than withdrawing XBT data, especially in the eastern half of the basin. The forecasts mainly indicate that the TAO/TRITON in situ temperature observations are essential to obtain optimum forecast skill. They are best combined with XBT, however, because this results in better predictions for the west Pacific. Furthermore, the XBTs play an important role in the North Atlantic. The ocean data assimilation performs less well in the tropical Atlantic. This may be partly a result of not having adequate observations of salinity.
Дисертації з теми "Ocean prediction through observation"
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Baker, Joshua L. "Mooring Analysis of the Ocean Sentinel through Field Observation and Numerical Simulation." Thesis, Oregon State University, 2013. http://hdl.handle.net/10945/43474.
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CIVINSMooring systems are used to secure offshore structures to the ocean floor. They can provide general station-keeping, where a ship, buoy, or platform is kept in a general location. They can also provide more finite positioning, where heading, draught, elevation, and GPS coordinates are tightly controlled. The behavior of a mooring system depends greatly on its configuration and components, which is discussed in more detail in this section. There are two major organizations that produce mooring system specifications: Det Norske Veritas (DNV) and the American Petroleum Institute. DNV specifications are available for free online, and several of them were reviewed during this study (DNV 2005, DNV 2008, and DNV 2010). Additionally, two reports prepared specifically for the Oregon Coast by Sound and Sea Technology Engineering Solutions (SST) were important sources for this study (SST 2009 and SST 2012).
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Abascal, Zorrilla Noélia. "Dynamics of the Amazon mud bank system through spatial observation and hydro-sedimentary modeling : application to he coastal domain of French Guiana." Thesis, Guyane, 2019. http://www.theses.fr/2019YANE0002.
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La côte de Guyane française se caractérise par la migration vers le nord-ouest de larges bancs de vase le long des côtes et par une concentration élevée de matières en suspension (MES) résultant de la forte influence des apports du fleuve Amazone. Les bancs de vase régissent la morphologie côtière régionale. Une meilleure compréhension de l’extension et de la dynamique des bancs est cruciale pour une gestion des écosystèmes et activités côtières à l'échelle de la région. Plusieurs études ont été effectuées sur la zone côtière de la Guyane française, fournissant des informations descriptives sur la morphologie et la vitesse de migration des bancs de vase. Cependant, la plupart des études ont porté sur la description des zones intertidales, alors que peu d’entre elles se sont concentrées sur la zone subtidale, qui pourtant, représente la partie la plus étendue des bancs de vase. L’objectif principal de cette thèse est d’adopter trois approches différentes telles que la télédétection haute résolution de la couleur de l’eau et les modèles numériques développés sur la base de mesures in-situ locales afin de mieux comprendre la morphologie de la partie subtidale et l’influence des forçages externes sur sa dynamique. Les précédentes approches sont complémentaires et forment un système de rétroaction interconnecté qui a permis la construction d’un modèle hydro-sédimentaire adapté à l’échelle de la région.L'exploitation optimale des informations fournies par les capteurs récents à haute résolution spatiale tels que Landsat 8-OLI est fortement conditionnée par la qualité du signal de réflectance marine. Ceci implique un développement méthodologique spécifique. L’un des problèmes majeurs en Guyane réside dans la capacité à corriger les données de réflectance marine de la contamination par la réflexion spéculaire du soleil. Ainsi, une méthode automatisée basée sur SWIR a été mise au point à l’aide d’une archive OLI de 4 ans réunie dans les eaux très turbides de la Guyane française. Des résultats satisfaisants basés sur les mesures in-situ de Rrs dans des zones affectées par le reflet du soleil mettent en évidence les performances pertinentes de la méthodologie proposée. La correction des reflets solaires a permis la récupération du signal de réflectance marine et l’estimation de la concentration des MES de surface estimée via le capteur OLI. Une méthode de détection de l'empreinte des bancs de vase a été développée via une approche basée sur les valeurs récurrentes de MES. Des bons résultats sont obtenus lors qu’on les compare à ceux obtenus via une localisation de la limite de l’amortissement de la houle sur les vases fluides subtidales associées aux bancs. Les taux de migration des bancs de vase en Guyane française ont été calculés en utilisant cette délimitation de la partie subtidale des bancs et ont montré des valeurs légèrement supérieures (2,31 km/an) à celles suggérées par des études antérieuresThe coast of French Guiana is characterized by the northwestward migration of large mud banks alongshore and by high concentration of suspended particulate matter (SPM) resulting from the strong influence of the Amazon River outflow. Mud banks govern the regional coastal morphology. A better understanding of its extension and dynamics is crucial for the coastal ecosystems management and activities at a regional scale. Several studies have been performed over French Guiana coastal area providing descriptive information about mud-bank morphology and migration speed. However, most studies have centred on the description of intertidal areas, whereas only few have focused on the subtidal zone, the biggest part of mud banks. The overarching aim of this thesis it to adapt two different approaches, such as high resolution remote sensing data and numerical models developed based on in-situ local measurements, to gather better insights into the subtidal part morphology and the influence of external forcings on its dynamics. The latter approaches are complementary and formed an interlinked feedback system that allowed the construction of a hydro-sedimentary model regionally adapted.Optimal exploitation of the information provided by recent high spatial resolution sensors such as Landsat 8-OLI is strongly conditioned by the quality of the water reflectance signal retrieval. This implies specific methodological development. One main issue in French Guiana stands in the ability to correct marine reflectance data for sun glint contamination. Thus, an automated SWIR based method has been developed using a 4-year OLI archive gathered over the very turbid waters of French Guiana. Satisfying results based on in-situ Rrs measurements in sun glint affected areas emphasize the relevant performance of the proposed methodology. Sun glint correction allowed the recovery of the marine reflectance signal and the estimation of surface OLI SPM concentration. A method to estimate the location of mud banks footprint has been developed based on SPM recurring values. A good performance was observed when the results were compared to those obtained by locating the limit of wave damping over the fluid mud of the subtidal part of mud banks. Mud-bank migration rates in French Guiana were calculated according to the delimitation of the subtidal part, and showed slightly higher values (2.31 km/year) than suggested by earlier studies. After obtaining remote sensing data and in-situ measurements, a 2D locally adapted hydro-sedimentary model was constructed based on the information provided by the latter approaches. The model takes into account the combined action of tide, currents, river discharge, wind and waves. Besides, the model also considered hydro-sedimentary processes related to cohesive sediments. Its development has followed three different steps: i) development of the hydrodynamic model; ii) development of the hydro-sedimentary model without considering wave-mud interaction; iii) and incorporation of waves to the hydro-sedimentary model, and has been validated via in-situ measurements and remote sensing data. The influence of the external forcings has been analysed for the dry and the rainy season. Despite the assumptions of the model, it reproduces qualitatively SPM trends and patterns on the subtidal part of the mud bank and the orders of magnitude are comparable to those provided by field and remote sensing data. This PhD provides evidences of the interest of these approaches and the combination of them to obtain better results in such complicated study area. The results obtained may help to further advance the state of knowledge on mud-bank processes and its migration
Книги з теми "Ocean prediction through observation"
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Rendine, John J. Real-time airborne ocean sampling and applications to naval operations. Monterey, Calif: Naval Postgraduate School, 1986.
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Bowers, David George, and Emyr Martyn Roberts. Tides: A Very Short Introduction. Oxford University Press, 2019. http://dx.doi.org/10.1093/actrade/9780198826637.001.0001.
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The tide is the greatest synchronized movement of matter on our planet. Every drop of seawater takes part in tidal motion, driven by the gravitational pull of the Moon and Sun. Tides: A Very Short Introduction blends clear explanations of well-known tidal phenomena with recent insights into the dynamics of the deep ocean and coastal seas, considering the tide’s nature and causes, its observation and prediction, and unusual tides and their relevance. It explains the importance of ocean tidal mixing as a key part of our planet’s climate-control system and for enhancing biological productivity. It also considers the effects of tidal processes beyond our own planet on the moons of Jupiter and Saturn.
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Wang, Bin. Intraseasonal Modulation of the Indian Summer Monsoon. Oxford University Press, 2018. http://dx.doi.org/10.1093/acrefore/9780190228620.013.616.
Повний текст джерелаАнотація:
The strongest Indian summer monsoon (ISM) on the planet features prolonged clustered spells of wet and dry conditions often lasting for two to three weeks, known as active and break monsoons. The active and break monsoons are attributed to a quasi-periodic intraseasonal oscillation (ISO), which is an extremely important form of the ISM variability bridging weather and climate variation. The ISO over India is part of the ISO in global tropics. The latter is one of the most important meteorological phenomena discovered during the 20th century (Madden & Julian, 1971, 1972). The extreme dry and wet events are regulated by the boreal summer ISO (BSISO). The BSISO over Indian monsoon region consists of northward propagating 30–60 day and westward propagating 10–20 day modes. The “clustering” of synoptic activity was separately modulated by both the 30–60 day and 10–20 day BSISO modes in approximately equal amounts. The clustering is particularly strong when the enhancement effect from both modes acts in concert. The northward propagation of BSISO is primarily originated from the easterly vertical shear (increasing easterly winds with height) of the monsoon flows, which by interacting with the BSISO convective system can generate boundary layer convergence to the north of the convective system that promotes its northward movement. The BSISO-ocean interaction through wind-evaporation feedback and cloud-radiation feedback can also contribute to the northward propagation of BSISO from the equator. The 10–20 day oscillation is primarily produced by convectively coupled Rossby waves modified by the monsoon mean flows. Using coupled general circulation models (GCMs) for ISO prediction is an important advance in subseasonal forecasts. The major modes of ISO over Indian monsoon region are potentially predictable up to 40–45 days as estimated by multiple GCM ensemble hindcast experiments. The current dynamical models’ prediction skills for the large initial amplitude cases are approximately 20–25 days, but the prediction of developing BSISO disturbance is much more difficult than the prediction of the mature BSISO disturbances. This article provides a synthesis of our current knowledge on the observed spatial and temporal structure of the ISO over India and the important physical processes through which the BSISO regulates the ISM active-break cycles and severe weather events. Our present capability and shortcomings in simulating and predicting the monsoon ISO and outstanding issues are also discussed.
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Clark, James S., Dave Bell, Michael Dietze, Michelle Hersh, Ines Ibanez, Shannon LaDeau, Sean McMahon, et al. Assessing the probability of rare climate events. Edited by Anthony O'Hagan and Mike West. Oxford University Press, 2018. http://dx.doi.org/10.1093/oxfordhb/9780198703174.013.16.
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This article focuses on the use of Bayesian methods in assessing the probability of rare climate events, and more specifically the potential collapse of the meridional overturning circulation (MOC) in the Atlantic Ocean. It first provides an overview of climate models and their use to perform climate simulations, drawing attention to uncertainty in climate simulators and the role of data in climate prediction, before describing an experiment that simulates the evolution of the MOC through the twenty-first century. MOC collapse is predicted by the GENIE-1 (Grid Enabled Integrated Earth system model) for some values of the model inputs, and Bayesian emulation is used for collapse probability analysis. Data comprising a sparse time series of five measurements of the MOC from 1957 to 2004 are analysed. The results demonstrate the utility of Bayesian analysis in dealing with uncertainty in complex models, and in particular in quantifying the risk of extreme outcomes.
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Herman, Bernard L. A South You Never Ate. University of North Carolina Press, 2019. http://dx.doi.org/10.5149/northcarolina/9781469653471.001.0001.
Повний текст джерелаАнотація:
Nestled between the Chesapeake Bay and the Atlantic Ocean, and stretching from Hampton Roads to Assateague Island, Virginia's Eastern Shore is a distinctly southern place with an exceptionally southern taste. Four centuries of encounter, imagination, and invention continue to shape the foodways of the Eastern Shore of Virginia, melding influences from Indigenous peoples, European migrants, enslaved and free West Africans, and more recent newcomers. Herman reveals how local ingredients and the cooks who have prepared them for the table have developed a distinctly American terroir--the flavors of a place experienced through its culinary and storytelling traditions. This terroir flourishes even as it confronts challenges from climate change, declining fish populations, and farming monoculture. Herman reveals this resilience through the recipes and celebrations that hold meaning, not just for those who live there but for all those folks who sit at their tables--and other tables near and far. Blending personal observation, history, memories of harvests and feasts, and recipes, Herman tells of life along the Eastern Shore through the eyes of its growers, watermen, oyster and clam farmers, foragers, church cooks, restaurant owners, and everyday residents.
Частини книг з теми "Ocean prediction through observation"
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Mimura, Satoru. "Reconstruction Through External Support: Key Observation in Aceh." In Recovery from the Indian Ocean Tsunami, 167–74. Tokyo: Springer Japan, 2014. http://dx.doi.org/10.1007/978-4-431-55117-1_12.
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Lovett, R. "Can a Solid be Turned into a Gas without Passing through a First Order Phase Transition?" In Observation, Prediction and Simulation of Phase Transitions in Complex Fluids, 641–54. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0065-6_17.
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Iwasaki, S. I., T. Eguchi, Y. Fujinawa, E. Fujita, I. Watabe, E. Fukuyama, H. Fujiwara, and K. Hishiki. "Precise Tsunami Observation System in Deep Ocean by an Ocean Bottom Cable Network for the Prediction of Earthquakes and Tsunamis." In Perspectives on Tsunami Hazard Reduction, 47–66. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-015-8859-1_4.
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Habyarimana, Ephrem, and Nicole Bartelds. "Yield Prediction in Sorghum (Sorghum bicolor (L.) Moench) and Cultivated Potato (Solanum tuberosum L.)." In Big Data in Bioeconomy, 219–33. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-71069-9_17.
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AbstractSorghum and potato pilots were conducted in this work to provide a solution to current limitations (dependability, cost) in crop monitoring in Europe. These limations include yield forecasting based mainly on field surveys, sampling, censuses, and the use of coarser spatial resolution satellites. We used the indexes decribing the fraction of absorbed photosynthetically active radiation as well as the leaf areas derived from Sentinel-2 satellites to predict yields and provide farmers with actionable advice in sorghum biomass and, in combination with WOFOST crop growth model, in cultivated potatoes. Overall, the Bayesian additive regression trees method modelled best sorghum biomass yields. The best explanatory variables were days 150 and 165 of the year. In potato, the use of earth observation information allowed to improve the growth model, resulting in better yield prediction with a limited number of field trials. The online platform provided the potato farmers more insight through benchmarking among themselves across cropping seasons, and observing in-field variability Site-specific management became easier based on the field production potential and its performance relative to surrounding fields. The extensive pilots run in this work showed that farming is a business with several variables which not all can be controlled by the farmer. The technologies developed herein are expected to inform about the farming operations, giving rise to well-informed farmers with the advantage to be able to adapt to the circumstances, mitigating production risks, and ultimately staying longer in the business.
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"Advancing an Ecosystem Approach in the Gulf of Maine." In Advancing an Ecosystem Approach in the Gulf of Maine, edited by Catherine L. Johnson and Jonathan A. Hare. American Fisheries Society, 2012. http://dx.doi.org/10.47886/9781934874301.ch15.
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<i>Abstract</i>.—Zooplankton communities perform a critical role as secondary producers in marine ecosystems. They are vulnerable to climate-induced changes in the marine environment, including temperature, stratification, and circulation, but the effects of these changes are difficult to discern without sustained ocean monitoring. The physical, chemical, and biological environment of the Gulf of Maine, including Georges Bank, is strongly influenced by inflow from the Scotian Shelf and through the Northeast Channel, and thus observations both in the Gulf of Maine and in upstream regions are necessary to understand plankton variability and change in the Gulf of Maine. Large-scale, quasi synoptic plankton surveys have been performed in the Gulf of Maine since Bigelow’s work at the beginning of the 20th century. More recently, ongoing plankton monitoring efforts include Continuous Plankton Recorder sampling in the Gulf of Maine and on the Scotian Shelf, U.S. National Marine Fisheries Service’s MARMAP (Marine Resources Monitoring, Assessment, and Prediction) and EcoMon (Ecosystem Monitoring) programs sampling the northeast U.S. Continental Shelf, including the Gulf of Maine, and Fisheries and Oceans Canada’s Atlantic Zone Monitoring Program on the Scotian Shelf and in the eastern Gulf of Maine. Here, we review and compare past and ongoing zooplankton monitoring programs in the Gulf of Maine region, including Georges Bank and the western Scotian Shelf, to facilitate retrospective analysis and broadscale synthesis of zooplankton dynamics in the Gulf of Maine. Additional sustained sampling at greater-than-monthly frequency at selected sites in the Gulf of Maine would be necessary to detect changes in phenology (i.e. seasonal timing of biological events). Sustained zooplankton sampling in critical nearshore fish habitats and in key feeding areas for upper trophic level organisms, such as marine mammals and seabirds, would yield significant insights into their dynamics. The ecosystem dynamics of the Gulf of Maine are strongly influenced by large-scale forcing and variability in upstream inflow. Improved coordination of sampling and data analysis among monitoring programs, effective data management, and use of multiple modeling approaches will all enhance the mechanistic understanding of the structure and function of the Gulf of Maine pelagic ecosystem.
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Arun Kumar R., Vijay S. Rajpurohit, and Sandeep Kautish. "A Study on Technology-LED Solutions for Fruit Grading to Address Post-Harvest Handling Issues of Horticultural Crops." In Modern Techniques for Agricultural Disease Management and Crop Yield Prediction, 203–21. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-5225-9632-5.ch009.
Повний текст джерелаАнотація:
The reduction of post-harvest losses and value addition of the horticultural corps has attained the higher priority of the current research works. Grading is the major phase in post-harvest handling. Presently grading is done on the basis of observation and through experience. Various drawbacks associated with such manual grading are subjectivity, tediousness, labor requirements, availability, inconsistency, etc. Such problems can be alleviated by incorporating automation in the process. Researchers round the clock are working towards the development of technology-driven solutions in order to grade/sort/classify various agricultural and horticultural produce. With the motto of helping the researchers in the field of grading and quality assessment of fruits and other horticulture products, the present work endeavors the following major contributions: (1) a precise and comprehensive review on technology-driven solutions for grading/sorting/classification of fruits, (2) major research gaps addressed by the researchers, and (3) research gaps to be addressed.
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Majhi, Babita, Sachin Singh Rajput, and Ritanjali Majhi. "Performance Evaluation of Machine Learning Techniques for Customer Churn Prediction in Telecommunication Sector." In Advances in Data Mining and Database Management, 262–74. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-6659-6.ch015.
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The principle objective of this chapter is to build up a churn prediction model which helps telecom administrators to foresee clients who are no doubt liable to agitate. Many studies affirmed that AI innovation is profoundly effective to anticipate this circumstance as it is applied through training from past information. The prediction procedure is involved three primary stages: normalization of the data, then feature selection based on information gain, and finally, classification utilizing different AI methods, for example, back propagation neural network (BPNNM), naïve Bayesian, k-nearest neighborhood (KNN), support vector machine (SVM), discriminant analysis (DA), decision tree (DT), and extreme learning machine (ELM). It is shown from simulation study that out of these seven methods SVM with polynomial based kernel is coming about 91.33% of precision where ELM is at the primary situation with 92.10% of exactness and MLANN-based CCP model is at third rank with 90.4% of accuracy. Similar observation is noted for 10-fold cross validation also.
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Mbuh, Mbongowo Joseph. "Application of Data Fusion for Uncertainty and Sensitivity Analysis of Water Quality in the Shenandoah River." In Geospatial Intelligence, 1383–410. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-8054-6.ch061.
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This article is aimed at demonstrating the feasibility of combining water quality observations with modeling using data fusion techniques for efficient nutrients monitoring in the Shenandoah River (SR). It explores the hypothesis; “Sensitivity and uncertainty from water quality modeling and field observation can be improved through data fusion for a better prediction of water quality.” It models water quality using water quality simulation programs and combines the results with field observation, using a Kalman filter (KF). The results show that the analysis can be improved by using more observations in watersheds where minor variations to the analysis result in large differences in the subsequent forecast. Analyses also show that while data fusion was an invaluable tool to reduce uncertainty, an improvement in the temporal scales would also enhance results and reduce uncertainty. To examine how changes in the field observation affects the final KF analysis, the fusion and lab analysis cross-validation showed some improvement in the results with a very high coefficient of determination.
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Dolman, Han. "The Hydrological Cycle and Climate." In Biogeochemical Cycles and Climate, 105–28. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198779308.003.0008.
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Water is a key part of the Earth system and interacts with climate through a variety of mechanisms. The chapter initially describes the effect of atmospheric moisture on the lapse rate and then discusses cloud formation and the main global reservoirs and fluxes, including precipitation, and discharge into the oceans. Atmospheric transport of water vapour, together with its relation to precipitation, is then discussed. It is shown that meridional transport can occur with a few very strong events, through atmospheric rivers. The difference between evaporation over the ocean and that over land is shown, with the help of data from Earth observation satellites, and the recycling of water is shown to depend very much on locality. Finally, the importance of frozen water on climate is described, using the recent decrease in Arctic sea ice, and the variability in ice sheet extent and consequent sea levels during the Last Glacial Maximum.
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Osterlind, Steven J. "At Least Squares." In The Error of Truth, 101–18. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198831600.003.0007.
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This chapter focuses on the next important mathematical invention: the method of least squares. First, it sets the historical context for its invention by describing the events in France and Germany leading up to the French Revolution. Next, the chapter describes how the method of least squares was invented twice, first by Adrien-Marie Legendre (as an appendix to his celestial investigations in Nouvelles méthodes pour la détermination des orbites des comètes), and then in a more sophisticated version by Carl Gauss, in Disquisitiones Arithmeticae. After that, an easy-to-understand description of method itself is given. Thus, the chapter goes from observation to probability and on to prediction, through regression, discussing ordinary least squares (OLS), intercepts, and slopes.
Тези доповідей конференцій з теми "Ocean prediction through observation"
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Fletcher, M., L. J. Pietrafesa, L. Xie, E. N. Buckley, D. E. Porter, and M. K. Moss. "Carolinas Coastal Ocean Observing and Prediction System: enhancing US integrated ocean observing system through improved regional coastal observations and services." In Oceans 2003. Celebrating the Past ... Teaming Toward the Future (IEEE Cat. No.03CH37492). IEEE, 2003. http://dx.doi.org/10.1109/oceans.2003.178399.
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Baker, Joshua, Solomon C. Yim, Ean Amon, Sean Moran, Terry Lettenmaier, and Annette von Jouanne. "Mooring Analysis of a NOMAD Buoy Through Field Testing and Numerical Simulation." In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-23334.
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This study presents a mooring analysis of the Ocean Sentinel buoy, which is a mobile test platform for Wave Energy Converters (WECs). The Ocean Sentinel is owned and operated by the Northwest National Marine Renewable Energy Center (NNMREC) at Oregon State University (OSU). The study involved a field observation as well as numerical modeling. The Ocean Sentinel was deployed from 7/29/2013 – 10/04/2013 at the NNMREC North Energy Test Site, which is located between 2–3 nautical miles (3.7–5.6 km) offshore of Yaquina Head, north of Newport, OR. It was configured in a three-point mooring with load cells on each mooring line. Prior to deployment, the numerical model was used for design and testing of the Ocean Sentinel mooring system. After deployment, recorded environmental conditions were coupled with the model to simulate deployed conditions, and model predictions of tension in the mooring lines were compared with actual results.
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Babanin, Alexander V., and Haoyu Jiang. "Ocean Swell: How Much Do We Know." In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-61692.
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Swell waves are present in more than 80% of ocean seas, and provide significant adverse impact on maritime operations. Their prediction by wave-forecast models, however, is poor, both in terms of wave amplitude and, particularly, arrival time. The very definition of ocean swell is ambiguous: while it is usually perceived as former wind-generated waves, in fact it may reconnect with the local wind through nonlinear interactions. The paper will bring together an overview of the complex swell problem. The visible swell attenuation is driven by a number of dissipative and non-dissipative processes. The dissipative phenomena include interaction with turbulence on the water and air sides, with adverse winds or currents. Non-dissipative contributions to the gradual decline of wave amplitude come from frequency dispersion, directional spreading, refraction by currents, and lateral diffraction of wave energy. The interactions with local winds/waves can, on the contrary, cause swell growth. Swell arrival time is the least understood and the most uncertain problem. Joint analysis of buoy observations and model reanalysis shows that swell can be tens of hours early or late by comparison with model predictions. Linear and nonlinear effects which can contribute to such biases are discussed.
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Haahr, Marie, Jonas Gudme, Jacob Sonne, Sten Overby, Torben Nielsen, and Adam Rubin. "H2S Consumption and the Derivation of a New Annulus Prediction Model for Offshore Flexible Pipes." In ASME 2016 35th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/omae2016-54472.
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This paper presents the outcome of investigations on the effects of H2S consumption in the annulus of a flexible pipe. Low-molecular gases, such as CH4, H2S, H2O and CO2, permeate slowly from the bore through the inner liner into the annular space between the inner liner and outer sheath of a flexible pipe. This space is densely packed with carbon steel armour wires leaving a very limited free volume. In the presence of water, a corrosive environment for the armour wires is generated and a risk of sour service cracking is introduced. H2S concentration in the annulus is traditionally calculated by balancing the inflow through inner liner and the outflow through outer sheath and vent valve. In order to assure H2S resistance of the armour wires towards calculated H2S concentrations, pipes for sour service are typically designed with lower strength wire grades of larger dimensions compared to the possibilities of sweet service pipes. Over the last decade, more and more offshore data has been obtained indicating considerably less H2S in the annulus than predicted by the traditional annulus models. This observation has triggered in-depth investigations of the complex corrosive H2S environment inside a flexible pipe annulus exposed to sour service conditions. An extensive small-scale test program has been conducted and showed that at permeation rates typical for flexible pipes, the consumption of H2S in the corrosion processes occurring in the annular space lowers the concentration and hence criticality of the H2S so significantly that it leaves the traditional models overly conservative to an extreme extent. Using this knowledge of consumption of the corrosive gases in the annulus has become an increasingly important topic with the focus on deeper waters, cost savings and service life extensions without compromising flexible pipe integrity. Based on experimental data obtained, a new annulus model for prediction of H2S pressure in annulus has been derived. Data is presented in this paper to illustrate the methodology for an annulus prediction where the consumption of H2S is included. The data presented covers laboratory tests with variations and effects of gas flux, H2S concentration and total pressure. A full-scale validation, led to an Independent Verification Agency certification of the model. With the introduction of this new annulus prediction model, a wider range of wire products becomes available for the pipe designers. Lower weight pipes with stronger armour wires render optimizations for both cost savings and applications at deeper waters possible.
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Lee, Kyung-ho, Kyung-su Kim, Young-soo Han, Jung-min Lee, Si-young Choi, and Chung-hyun Kim. "Framework of Ubiquitous Sensor Network for the Crack Monitoring of Offshore Structures." In ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79124.
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According to climate change, design paradigm for Marine structure is being changed too. Many researches and practices are carried out countermeasures for climate change after extensive damage from TSUNAMI and Hurricane Katrina. And some of these activities are interest on fatigue crack problem. There are only few ways to prevent Marine structure’s fatigue failure as yet. Most one is applying safety factor to structural strength, another one is carry out fatigue status observation by naked eyes. But those ways have some problems about measuring accuracy and observing continuability. Also Carrying out Marine structure design depend on experiences about structural strength has possibility of in-efficiency. And it might not deal with structural safety ensuring by climate changing immediately. According to weather condition and observing location, it even should be impossible to continue monitoring. As previously stated, to improve problems of structural fatigue life monitoring system, this paper introduce convergence technology based on Ubiquitous network system through analyzing system requirements and developing system framework. Also we make a prototype and carry out test to confirm possibility of fatigue strength prediction system based on Ubiquitous sensor network applying to Marine structure.
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Tom, Joe G., and David J. White. "Effect of Drainage on Upheaval Buckling Susceptibility of Buried Pipelines." In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-61046.
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This paper investigates the effect of soil drainage on the uplift resistance of buried pipelines, and their susceptibility to upheaval buckling. The uplift resistance of buried pipelines is considered through analytical and numerical predictions for both drained and undrained conditions. Combinations of soil strength parameters for typical soils are estimated based on common correlations. For certain ranges of typical normally consolidated soil conditions, particularly those with high critical state friction angles, the drained uplift resistance may be lower than the undrained resistance. This observation is important because in typical practice only drained or undrained behaviour is considered depending on the general type of soil backfill used. In this case, the critical or minimum uplift resistance may be overlooked. Further, the changing undrained uplift mechanism between shallow and deep conditions is investigated. It is found that the common approach of considering the minimum of either a local (flow around) or global (vertical slip plane) failure can overestimate the uplift resistance in normally consolidated soils.
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Griffiths, Terry, Scott Draper, Liang Cheng, Feifei Tong, Antonino Fogliani, David White, Fraser Johnson, Daniel Coles, Stephen Ingham, and Caroline Lourie. "Subsea Cable Stability on Rocky Seabeds: Comparison of Field Observations Against Conventional and Novel Design Methods." In ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-77130.
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As offshore renewable energy projects progress from concept demonstration to commercial-scale developments there is a need for improved approaches beyond conventional cable engineering design methods that have evolved from larger diameter pipelines for the oil and gas industry. New approaches are needed to capture the relevant physics for small diameter cables on rocky seabeds to reduce the costs and risks of power transmission and increase operational reliability. This paper reports on subsea cables that MeyGen installed for Phase 1a of the Pentland Firth Inner Sound tidal stream energy project. These cables are located on rocky seabeds in an area where severe metocean conditions occur. ROV field observation of these cables shows them to be stable on the seabed with little or no movement occurring over almost all of the cable routes, despite conventional engineering methods predicting significant dynamic movement. We cite recent research undertaken by the University of Western Australia (UWA) to more accurately assess the hydrodynamic forces and geotechnical interaction of cables on rocky seabeds. We quantify the conformity between the cables and the undulating rocky seabed, and the distributions of cable-seabed contact and spanning via simulations of the centimetric-scale seabed bathymetry. This analysis leads to calculated profiles of lift, drag and seabed friction along the cable, which show that all of these load and reaction components are modelled in an over-conservative way by conventional pipeline engineering techniques. Overall, our analysis highlights that current cable stability design can be unnecessarily conservative on rocky seabeds. Our work foreshadows a new design approach that offers more efficient cable design to reduce project capex and enhance through-life integrity management.
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Chen, Yufei, Changbao Jiang, Guangzhi Yin, Andrew K. Wojtanowicz, and Dongming Zhang. "Triaxial Testing of Gas Shale Permeability Dependence on Heterogeneous Stress With Respect to Bedding." In ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-96707.
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Abstract Shale gas has recently become the most promising source of unconventional hydrocarbon energy. Shale gas well deliverability and economics depend on extremely low permeability that is not only dependent on the rock bedding trend but is also controlled by in-situ stresses. Thus, prediction of well’s deliverability requires understanding permeability of a dipping shale with natural bedding under conditions of unequal stresses in-situ. The purpose of this study was to determine relative contributions of normal and tangential stresses with respect to the rock bedding plane on permeability evolution of Longmaxi shale in the Sichuan Basin, southwest China. The study involved an analysis of the rock bedding structure, followed with triaxial testing of rock samples and theoretical modeling. We used SEM observation to identify existence of microfractures and numerous inter-particle pores along the shale bedding planes that provide dominant pathways for gas flow depending upon closing stress value. Stress-dependent permeability was tested with a newly-developed multi-functional true triaxial geophysical (TTG) apparatus providing for a steady state gas flow through the rock sample under conditions of normal stress and two unequal tangential stresses. Also simulated were the effects of stress-bedding and load cycling. The results showed shale permeability reduction during the stress loading process and its gradual recovery during the unloading process for both normal and tangential stress loading cycles. A hysteresis of the permeability response to cyclic loading was the largest when normal stress cycling was dominant. Moreover, permeability change was more pronounced in response to normal stress but some effects of the tangential stresses were also observed — particularly when the tangential stresses were dominant. A theoretical model was derived to describe permeability change with effective stress in the presence of normal and tangential stresses. The model was empirically matched with the experimental results. Assessment of relative contributions of normal and tangential stresses was quantified with the analysis of variance (ANOVA). The analysis revealed significance levels of normal stress, and two tangential stresses σt1 and σt2 on shale permeability as 81%, 5% and 14%, respectively, showing dominant effect of normal stress with clear contribution of tangential stresses. An almost 20-percent contribution of tangential stress loading to permeability response indicates a need for improvement in computing effective stress in permeability predictions of the Longmaxi shale. It also warrants testing other gas shales to specifically determine the effect.
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Jacobs, Gregg A., Joseph M. D'Addezio, Hans E. Ngodock, and Innocent Souopgui. "Observation and model resolution implication to ocean prediction." In Global Oceans 2020: Singapore - U.S. Gulf Coast. IEEE, 2020. http://dx.doi.org/10.1109/ieeeconf38699.2020.9389409.
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Elosta, Hany, Shan Huang, and Atilla Incecik. "Seabed Interaction Modelling Effects on the Global Response of Catenary Pipeline: A Case Study." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-10782.
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A steel catenary riser (SCR) attached to a floating platform at its upper end encounters oscillations in and near its touchdown zone (TDZ), which results in interaction with the seabed. Field observations and design analysis of SCRs show that the highest stress and greatest fatigue damage occurred near the touchdown point where the SCR first touches the seabed soil. The challenges regarding the fatigue damage assessment of an SCR in the TDZ are primarily because of the non-linear behaviour of SCR–seabed interaction and considerable uncertainty in seabed interaction modelling and geotechnical parameters. Analysis techniques have been developed in the two main areas: SCR–seabed interaction modelling and the influence of the uncertainty in the geotechnical parameters on the dynamic response and fatigue performance of SCRs in the TDZ. Initially, this study discusses the significance of SCR–seabed interaction on the response of an SCR for deepwater applications when subjected to random waves on soft clay using the commercial code OrcaFlex for non-linear time domain simulation. In the next step, this study investigates the sensitivity of fatigue performance to geotechnical parameters through a parametric study. It is proven that employing the improved lateral SCR-seabed interaction model with accurate prediction of soil stiffness and riser penetration with cyclic loading enables us to obtain dynamic global riser performance in the TDZ with better accuracy. The fatigue analyses results prove that the confounding results indicated by the previous research studies on the SCR in the TDZ are due to different geotechnical parameters imposed with the seabed interaction model. The main benefit of employing non-linear seabed approach is to capture the entity of realistic soil interaction behaviour in modelling and analysis and to predict the likelihood of the fatigue damage of the SCR with seabed interaction, thereby minimising the risk of the loss of the containment with the associated environmental impact.
Звіти організацій з теми "Ocean prediction through observation"
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Baker, Joshua L. Mooring Analysis of the Ocean Sentinel through Field Observation and Numerical Simulation. Fort Belvoir, VA: Defense Technical Information Center, November 2013. http://dx.doi.org/10.21236/ada611180.
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Bruno, Michael S., and Alan F. Blumberg. The Stevens Integrated Observation and Prediction System: Enhancement through New Sensors and Data Assimilation Techniques. Fort Belvoir, VA: Defense Technical Information Center, September 2006. http://dx.doi.org/10.21236/ada611943.
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