Synergistic Use of Satellite and In-Situ Current Data to Improve the Characterisation of Seasonal Trends

2009 ◽  
Author(s):  
Liam Harrington-Missin ◽  
Mark Calverley ◽  
Gus Jeans
Keyword(s):  
Current Data ◽  
Seasonal Trend ◽  
Measured Signal ◽  
Geostrophic Current ◽  
Geostrophic Currents ◽  
Current Regime ◽  
Long Period ◽  
In Situ Data ◽  
One Year

The synergistic use of measured in-situ current data and altimetry derived geostrophic current data provides improved seasonal characterisation of the current regime, West of Shetland. In September 2007, considerable downtime was experienced by an offshore operator, West of Shetland, as a result of unexpectedly high currents persisting for a number of days. This downtime was unanticipated following conclusions derived from one year of in-situ measured data, which suggested a most favourable current regime during the months August to October. Ten years of altimetry derived geostrophic currents were utilised in conjunction with approximately 3 years of in-situ data to assess the validity of the reported seasonal trend. The altimetry derived geostrophic currents correlated well with the dominating long period signal extracted from the in-situ data. Seasonal comparison between the altimetry derived geostrophic currents and the total measured signal showed the previously available measurement year had a relatively benign September. Based on the 10 years of satellite data, the inter-annual variability of the current regime West of Shetland does not show any clear seasonal trend.

scholarly journals Ant Colony Optimization for Data Acquisition Mission Planning

2014 ◽  
Vol 5 (2) ◽  
pp. 3-11 ◽  
Author(s):  
Giancarlo Colmenares ◽  
Fadi Halal ◽  
Marek B. Zaremba
Keyword(s):  
Data Acquisition ◽  
Ant Colony Optimization ◽  
Monitoring System ◽  
Water Quality Monitoring ◽  
Current Data ◽  
Ant Colony ◽  
Continuous Space ◽  
In Situ Data ◽  
Water Pollutant

Abstract The probabilistic Ant Colony Optimization (ACO) approach is presented to solve the problem of designing an optimal trajectory for a mobile data acquisition platform. An ACO algorithm optimizes an objective function defined in terms of the value of the acquired data samples subject to different sets of constraints depending on the current data acquisition strategy. The analysis presented in this paper focuses on an environment monitoring system, which acquires in-situ data for precise calibration of a water quality monitoring system. The value of the sample is determined based on the concentration of the water pollutant, which in turn is obtained through processing of multi-spectral satellite imagery. Since our problem is defined in a continuous space of coordinates, and in some strategies each point is able to connect to any other point in the space, we adopted a hybrid model that involves a connection graph and also a spatial grid.

scholarly journals A robust method for removal of glint effects from satellite ocean colour imagery

2014 ◽  
Vol 11 (6) ◽  
pp. 2791-2829 ◽  
Author(s):  
R. K. Singh ◽  
P. Shanmugam
Keyword(s):  
Wind Speed ◽  
Geographical Location ◽  
Processing System ◽  
Correction Method ◽  
Measured Signal ◽  
Ocean Colour ◽  
Tropical Regions ◽  
In Situ Data ◽  
Background Absorption

Abstract. Removal of the glint effects from satellite imagery for accurate retrieval of water-leaving radiances is a complicated problem since its contribution in the measured signal is dependent on many factors such as viewing geometry, sun elevation and azimuth, illumination conditions, wind speed and direction, and the water refractive index. To simplify the situation, existing glint correction models describe the extent of the glint-contaminated region and its contribution to the radiance essentially as a function of the wind speed and sea surface slope that often lead to a tremendous loss of information with a considerable scientific and financial impact. Even with the glint-tilting capability of modern sensors, glint contamination is severe on the satellite-derived ocean colour products in the equatorial and sub-tropical regions. To rescue a significant portion of data presently discarded as "glint contaminated" and improving the accuracy of water-leaving radiances in the glint contaminated regions, we developed a glint correction algorithm which is dependent only on the satellite derived Rayleigh Corrected Radiance and absorption by clear waters. The new algorithm is capable of achieving meaningful retrievals of ocean radiances from the glint-contaminated pixels unless saturated by strong glint in any of the wavebands. It takes into consideration the combination of the background absorption of radiance by water and the spectral glint function, to accurately minimize the glint contamination effects and produce robust ocean colour products. The new algorithm is implemented along with an aerosol correction method and its performance is demonstrated for many MODIS-Aqua images over the Arabian Sea, one of the regions that are heavily affected by sunglint due to their geographical location. The results with and without sunglint correction are compared indicating major improvements in the derived products with sunglint correction. When compared to the results of an existing model in the SeaDAS processing system, the new algorithm has the best performance in terms of yielding physically realistic water-leaving radiance spectra and improving the accuracy of the ocean colour products. Validation of MODIS-Aqua derived water-leaving radiances with in-situ data also corroborates the above results. Unlike the standard models, the new algorithm performs well in variable illumination and wind conditions and does not require any auxiliary data besides the Rayleigh-corrected radiance itself. Exploitation of signals observed by sensors looking within regions affected by bright white sunglint is possible with the present algorithm when the requirement of a stable response over a wide dynamical range for these sensors is fulfilled.

Wind Gust Quantification Using Seismic Measurements

2017 ◽  
Author(s):  
F. Letson ◽  
W. Hu ◽  
R. J. Barthelmie ◽  
J. Tytell ◽  
S. C. Pryor
Keyword(s):  
Cumulative Probability ◽  
Wind Gust ◽  
Independent Data ◽  
Ground Acceleration ◽  
Wind Speeds ◽  
In Situ Data ◽  
Sonic Anemometers ◽  
One Year ◽  
Wind Resource

Improved understanding of wind gust climates may be of great value to the wind energy industry, and is currently hampered by a lack of high-quality in situ data in wind resource rich environments. Thus, we are examining the potential to supplement anemometry with data from seismometers, including those deployed as part of the USArray Transportable Array (TA). Two models of the relationship between gust magnitude and ground motion are evaluated based on their skill at describing the distribution of gust wind speeds over 1 year using seismic data. The approach is illustrated, using observed gust magnitudes obtained from sonic anemometers located at or near the 15 TA seismic stations. One deterministic and one probabilistic wind-seismic model are conditioned using one year of 5-minute resolution data and tested on a second year of independent data. Both models relate the variance of ground acceleration in the frequency range of 0.01 to 0.1 Hz (P) to gust speed (Ug) but differ in their functional form. The probabilistic model is found to perform well in predicting the gust distribution in independent data, and at the 15 sites considered herein has an integrated error across the entire cumulative probability distribution that is only 5% of the mean gust magnitude.

The Application of Nonlinear Fourier Analysis to Soliton Quantification for Offshore Engineering

2017 ◽  
Author(s):  
Gus Jeans ◽  
Wenting Xiao ◽  
Alfred R. Osborne ◽  
Christopher R. Jackson ◽  
Douglas A. Mitchell
Keyword(s):  
Fourier Analysis ◽  
Extreme Values ◽  
Current Data ◽  
Temperature Measurements ◽  
Computational Techniques ◽  
Primary Input ◽  
Measured Current ◽  
In Situ Data ◽  
Offshore Engineering

This paper describes the first application of Nonlinear Fourier Analysis to the quantification of internal soliton current speeds in offshore engineering design. Large amplitude solitary internal waves produce strong, rapidly varying currents that may cause hazards to offshore operations in several regions of the world. These phenomena are commonly referred to in Industry as “solitons.” Soliton quantification was undertaken using the latest methodologies and software available from the Nonlinear Fourier Analysis Spectral Tools (NFAST) Joint Industry Project. Solitons require rapidly sampled in-situ data for reliable quantification. Such measurements are typically of very short duration compared to the time scales needed for engineering quantification. Similarly, numerical models capable of representing solitons are computationally expensive, and thus have limited capabilities for efficiently developing the long-term simulations required to supplement in-situ data. NFAST aims to address these issues by enabling new Hyperfast Nonlinear Fourier Analysis computational techniques. Interface displacements, derived from temperature measurements, were the primary input to soliton quantification. Associated current speeds were estimated from relevant theory and validated with available measured current data. In this particular case, the temperature measurements are considered to be more reliable than using the measured current data directly. Application of NFAST codes produced a synthetic dataset of soliton amplitudes and speeds with an effective duration of approximately 100 years, a period that is considerably greater than the duration of available measured data. This provided extreme values consistent with extrapolation of the measured soliton data, but with a considerable reduction in uncertainty.

Deepwater Current Profile Data Sources for Riser Engineering Offshore Brazil

2012 ◽  
Author(s):  
Gus Jeans ◽  
Marc Prevosto ◽  
Liam Harrington-Missin ◽  
Christophe Maisondieu ◽  
Christelle Herry ◽  
...  
Keyword(s):  
Numerical Model ◽  
Primary Source ◽  
Current Data ◽  
Data Sources ◽  
Model Data ◽  
Current Profile ◽  
Profile Data ◽  
Site Specific ◽  
In Situ Data

A variety of current profile data sources are compared for a deepwater site offshore Brazil. These data were gathered for consideration as part of the Worldwide Approximations of Current Profiles (WACUP) Joint Industry Project, described separately in OMAE2012-83348. The primary source of data for current profile characterisation is site specific full water column measurement. Sufficiently high vertical and temporal resolutions are required to capture the dominant oceanographic processes. Such in-situ data are generally expensive and time consuming to collect, so there is an increasing tendency for numerical model current data to be considered for engineering applications. In addition to being relatively inexpensive and quick to obtain, model data are also typically of much longer duration. This potentially allows inter-annual variability and rare extreme events to be captured. However, the accuracy and reliability of numerical model data remains questionable, or unproven, in many deepwater development regions. This paper explores the suitability of such models to represent a deepwater site offshore Brazil, in relation to the key oceanographic processes revealed within the in-situ data.

Deepwater Current Profile Data Sources for Riser Engineering Offshore West Africa

2013 ◽  
Author(s):  
Gus Jeans ◽  
Liam Harrington-Missin ◽  
Mark Calverley ◽  
Christophe Maisondieu ◽  
Cyril Frelin ◽  
...  
Keyword(s):  
Numerical Model ◽  
West Africa ◽  
Primary Source ◽  
Current Data ◽  
Model Data ◽  
Current Profile ◽  
Field Development ◽  
In Situ Data ◽  
Reliable Quantification

Reliable quantification of current profiles is required for safe and cost effective offshore exploration and field development. The current regime offshore West Africa is often considered benign, compared to some regions of oil and gas activity, but still presents challenges to reliable quantification. A key challenge to all offshore developments is acquisition of appropriate data. The primary source of data for riser design is site specific full water column measurement. Such in-situ data are generally expensive and time consuming to collect, so there is an increasing tendency for numerical model current data to be considered. Model data are often relatively quick and inexpensive to obtain, with the added benefit of a much longer duration, potentially allowing inter-annual variability and extreme events to be captured. However, the accuracy and reliability of numerical model data remains questionable, or unproven, in many deepwater development regions. This paper explores the suitability of such models to represent a deepwater site offshore West Africa, in relation to the key oceanographic processes revealed within the in-situ data.

scholarly journals Estimation of geostrophic current in the Red Sea based on sea level anomalies derived from extended satellite altimetry data

Ocean Science ◽  
2019 ◽  
Vol 15 (3) ◽  
pp. 477-488 ◽  
Author(s):  
Ahmed Mohammed Taqi ◽  
Abdullah Mohammed Al-Subhi ◽  
Mohammed Ali Alsaafani ◽  
Cheriyeri Poyil Abdulla
Keyword(s):  
Sea Level ◽  
Red Sea ◽  
Current Data ◽  
Western Coast ◽  
Geostrophic Current ◽  
Geostrophic Currents ◽  
The North ◽  
Sea Level Anomalies ◽  
Western Side ◽  
Anticyclonic Eddies

Abstract. Geostrophic current data near the coast of the Red Sea have large gaps. Hence, the sea level anomaly (SLA) data from Jason-2 have been reprocessed and extended towards the coast of the Red Sea and merged with AVISO data at the offshore region. This processing has been applied to build a gridded dataset to achieve the best results for the SLA and geostrophic current. The results obtained from the new extended data at the coast are more consistent with the observed data (conductivity–temperature–depth, CTD) and hence geostrophic current calculation. The patterns of SLA distribution and geostrophic currents are divided into two seasons: winter (October–May) and summer (June–September). The geostrophic currents in summer are flowing southward over the Red Sea except for narrow northward flow along the east coast. In winter, currents flow to the north for the entire Red Sea except for a small southward flow near the central eastern and western coast. This flow is modified by the presence of cyclonic and anticyclonic eddies, which are more concentrated in the central and northern Red Sea. The results show anticyclonic eddies (AEs) on the eastern side of the Red Sea and cyclonic eddies (CEs) on the western side during winter. In summer, cyclonic eddies are more dominant for the entire Red Sea. The result shows a change in some eddies from anticyclonic during winter to cyclonic during summer in the north between 26.3 and 27.5∘ N. Furthermore, the life span of cyclonic eddies is longer than that of anticyclonic eddies.

Current Profile Data Sources for Engineering Design West of Shetlands

2014 ◽  
Author(s):  
Gus Jeans ◽  
Joe Fox ◽  
Claire Channelliere
Keyword(s):  
Numerical Model ◽  
Engineering Design ◽  
Current Data ◽  
Data Sources ◽  
Model Data ◽  
Current Profile ◽  
Profile Data ◽  
Field Development ◽  
In Situ Data

Current profile data sources considered for derivation of engineering design criteria West of Shetland are described. The region is impacted by a variety of oceanographic processes that combine to produce a complex current regime. Reliable quantification of the resulting current profiles is required for safe and cost effective offshore exploration and field development. A key challenge to all offshore developments is acquisition of appropriate data. Site specific measurement remains the primary current profile data source for engineering applications, with full water column coverage at sufficient resolution required for riser design. Such in-situ data are generally expensive and time consuming to collect, so there is an increasing tendency for numerical model current data to be considered. Model data are often relatively quick and inexpensive to obtain, with the added benefit of a much longer duration, potentially allowing inter-annual variability and extreme events to be captured. However, the accuracy and reliability of numerical model data remains questionable, or unproven, in many deepwater development regions. This paper describes a recent study in which in-situ data remained the primary source for derivation of current profile criteria for engineering design. Short duration proprietary data were supplemented by additional public domain data from nearby sites in a regional synthesis, with critical results. The performance and benefits of readily available model data are also considered.

STORM ICE OIL WIND WAVE WATCH SYSTEM (SIOWS): WEB GIS APPLICATION FOR MONITORING THE ARCTIC

2017 ◽  
Author(s):  
Alexander Myasoedov ◽  
Alexander Myasoedov ◽  
Sergey Azarov ◽  
Sergey Azarov ◽  
Ekaterina Balashova ◽  
...  
Keyword(s):  
Satellite Data ◽  
Wind Wave ◽  
Arctic Region ◽  
Web Gis ◽  
The Arctic ◽  
Flexible Tool ◽  
In Situ Data ◽  
Current State ◽  
Watch System

Working with satellite data, has long been an issue for users which has often prevented from a wider use of these data because of Volume, Access, Format and Data Combination. The purpose of the Storm Ice Oil Wind Wave Watch System (SIOWS) developed at Satellite Oceanography Laboratory (SOLab) is to solve the main issues encountered with satellite data and to provide users with a fast and flexible tool to select and extract data within massive archives that match exactly its needs or interest improving the efficiency of the monitoring system of geophysical conditions in the Arctic. SIOWS - is a Web GIS, designed to display various satellite, model and in situ data, it uses developed at SOLab storing, processing and visualization technologies for operational and archived data. It allows synergistic analysis of both historical data and monitoring of the current state and dynamics of the "ocean-atmosphere-cryosphere" system in the Arctic region, as well as Arctic system forecasting based on thermodynamic models with satellite data assimilation.

scholarly journals Critical Dynamics of Defects and Mechanisms of Damage-Failure Transitions in Fatigue

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2554
Author(s):  
Oleg Naimark ◽  
Vladimir Oborin ◽  
Mikhail Bannikov ◽  
Dmitry Ledon
Keyword(s):  
Fatigue Damage ◽  
Kinetic Equations ◽  
Experimental Methodology ◽  
Preliminary Deformation ◽  
Scaling Properties ◽  
In Situ Data ◽  
Number Of Cycles ◽  
Fish Eye ◽  
Very High

An experimental methodology was developed for estimating a very high cycle fatigue (VHCF) life of the aluminum alloy AMG-6 subjected to preliminary deformation. The analysis of fatigue damage staging is based on the measurement of elastic modulus decrement according to “in situ” data of nonlinear dynamics of free-end specimen vibrations at the VHCF test. The correlation of fatigue damage staging and fracture surface morphology was studied to establish the scaling properties and kinetic equations for damage localization, “fish-eye” nucleation, and transition to the Paris crack kinetics. These equations, based on empirical parameters related to the structure of the material, allows us to estimate the number of cycles for the nucleation and advance of fatigue crack.

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