SbPOM: A parallel implementation of Princenton Ocean Model

This paper presents the Stony Brook Parallel Ocean Model (sbPOM) for execution on workstations, Linux clusters and massively parallel supercomputers. The sbPOM is derived from the Princenton Ocean Model (POM), a widely used community ocean circulation model. Two-dimensional data decomposition of the horizontal domain is used with a halo of ghost cells to minimize communication between processors. Communication consists of the exchange of information between neighbor processors based on the Message Passing Interface (MPI) standard interface. The Parallel-NetCDF library is also implemented to achieve a high efficient input and output (I/O). Parallel performance is tested on an IBM Blue Gene/L massively parallel supercomputer, and efficiency using up to 2048 processors remains very good. © 2012 Elsevier Ltd.his research utilized resources at the New York Center for Computational Sciences at Stony Brook University/Brookhaven National Laboratory which was supported by the U.S. Department of Energy under Contract No. DE-AC02-98CH10886 and by the State of New York. A. Jordi's work was supported by a Ramón y Cajal grant from MICINNPeer Reviewe

Over what area did the oil and gas spread during the 2010 Deepwater Horizon oil spill?

Author Posting. © The Oceanography Society, 2016. This article is posted here by permission of The Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 29, no. 3 (2016): 96–107, doi:10.5670/oceanog.2016.74.The 2010 Deepwater Horizon (DWH) oil spill in the Gulf of Mexico resulted in the collection of a vast amount of situ and remotely sensed data that can be used to determine the spatiotemporal extent of the oil spill and test advances in oil spill models, verifying their utility for future operational use. This article summarizes observations of hydrocarbon dispersion collected at the surface and at depth and our current understanding of the factors that affect the dispersion, as well as our improved ability to model and predict oil and gas transport. As a direct result of studying the area where oil and gas spread during the DWH oil spill, our forecasting capabilities have been greatly enhanced. State-of-the-art oil spill models now include the ability to simulate the rise of a buoyant plume of oil from sources at the seabed to the surface. A number of efforts have focused on improving our understanding of the influences of the near-surface oceanic layer and the atmospheric boundary layer on oil spill dispersion, including the effects of waves. In the future, oil spill modeling routines will likely be included in Earth system modeling environments, which will link physical models (hydrodynamic, surface wave, and atmospheric) with marine sediment and biogeochemical components.This research was made possible by a grant from BP/The Gulf of Mexico Research Initiative to the CARTHE and Deep-C Consortia, and by contract M12PC00003 from the Bureau of Ocean Energy Management (BOEM)

Ocean currents and coastal exposure to offshore releases of passively transported material in the Gulf of Mexico

The Gulf of Mexico (GoM) is heavily exploited by the oil industry. Incidental oil releases, such as the 2010 blowout of the Deepwater Horizon platform, lead to a large scale dispersion of pollutants by ocean currents, contaminating the coastline and damaging the ecosystems. In order to determine whether the ocean dynamics hampers or conversely fosters the landing of material in the coastal regions, we simulate more than 29000 individual tracer releases in the offshore waters of the GoM. We assume that the tracers are not decaying and transported passively by the ocean currents. In a first part of our study we focus on the mean dispersion pattern of 80 releases occurring at the location of the Deepwater Horizon. In a second part, we generalize the metrics that we defined to the whole GoM. Our study shows that releases occurring in specific regions, i.e the bay of Campeche, off the Mississipi-Alabama-Florida and the West Florida shelfs are associated with higher environmental costs as the ocean currents steer the released material toward the productive coastal ecosystems and foster landings. Conversely, the tracers released off the Louisiana-Texas-shelfs and the center of the Gulf of Mexico are less threatening for coastal regions as the material recirculates offshore. We show that the coastline of the southwest part of the Bay of Campeche, the Mississipi's mouth and the Island of Cuba are particularly exposed as 70 % of the landings occur in these 3 regions

Deflection of natural oil droplets through the water column in deep-water environments: The case of the Lower Congo Basin

International audienceNumerous recurrent seep sites were identified in the deep-water environment of the Lower Congo Basin from the analysis of an extensive dataset of satellite-based synthetic-aperture radar images. The integration of current data was used to link natural oil slicks with active seep-related seafloor features. Acoustic Doppler current profiler measurements across the water column provided an efficient means to evaluate the horizontal deflection of oil droplets rising through the water column. Eulerian propagation model based on a range of potential ascension velocities helped to approximate the path for rising oil plume through the water column using two complementary methods. The first method consisted in simulating the reversed trajectory of oil droplets between sea-surface oil slick locations observed during current measurements and seep-related seafloor features while considering a range of ascension velocities. The second method compared the spatial spreading of natural oil slicks from 21 years of satellite monitoring observations for water depths ranging from 1200 to 2700 m against the modeled deflections during the current measurement period. The mapped oil slick origins are restricted to a 2.5 km radius circle from associated seep-related seafloor features. The two methods converge towards a range of ascension velocities for oil droplets through the water column, estimated between 3 and 8 cm s-1. The low deflection values validate that the sub-vertical projection of the average surface area of oil slicks at the sea surface can be used to identify the origin of expelled hydrocarbon from the seafloor, which expresses as specific seafloor disturbances (i.e. pockmarks or mounds) known to expel fluids

Quantitative assessment of two oil-in-ice surface drift algorithms

The ongoing reduction in extent and thickness of sea ice in the Arctic might result in an increase of oil spill risk due to the expansion of shipping activity and oil exploration shift towards higher latitudes. This work assessed the response of two oil-in-ice surface drift models implemented in an open-source Lagrangian framework. By considering two numerical modeling experiments, our main finding indicates that the drift models provide fairly similar outputs when forced by the same input. It was also found that using higher resolution ice-ocean model does not imply better results. We highlight the role of sea ice in the spread, direction and distance traveled by the oil. The skill metric seems to be sensitive to the drift location, and drift model re-initialization is required to avoid forecast deterioration and ensure the accurate tracking of oil slicks in real operations.publishedVersio

Numerical modeling of oil pollution in the Eastern Mediterranean Sea

This chapter presents a summary of major applications in numerical oil spill predictions for the Eastern Mediterranean Sea. Since the trilateral agreement between Cyprus, Egypt, and Israel back in 1997, under the framework of the subregional contingency plan for preparedness and response to major oil spill pollution incidents in the Eastern Mediterranean Sea, several oil spill models have been implemented during real oil pollution accidents and after oil spills that were detected from satellite remote sensing SAR data. In addition, several projects cofinanced by the European Commission addressed particularly issues with oil spill modeling, taking the advantage of developments in operational oceanography, as well as collaboration with the Mediterranean Oceanographic Network for Global Ocean Observing System (MONGOOS), with the European Maritime Safety Agency CleanSeaNet (EMSA-CSN), and Regional Marine Pollution Emergency Response Centre for the Mediterranean Sea (REMPEC). Major oil pollution incidents in the Eastern Mediterranean and the oil spill modeling applications carried out are summarized in this work. Three well-established operational oil spill modeling systems – two of them characterized by different numerical tools MEDSLIK, MEDSLIK II, and the POSEIDON oil spill models – are described in terms of their applicability to real oil spill pollution events, the Lebanon oil pollution crisis in summer 2006, the case Costa Concordia accident, and the spill event associated with the collision of two cargo vessels in the North Aegean Sea in June 2009. Finally, an overview of the present-day capability of Eastern Mediterranean countries in oil spill modeling is provided in this chapter

Deep Convection and Oil Spill

학위논문(박사) -- 서울대학교대학원 : 자연과학대학 지구환경과학부, 2022. 8. 조양기.The turbulent ocean processes around Korea were simulated using LES, and their characteristics were investigated. Most serious ocean accidental spills occur during strong winds, and the diffusion of pollutants depends on wave-driven upper ocean turbulence such as Langmuir circulation (LC) and wave breaking (WB). However, the effects of LC and WB on advection speed and diffusion rate are not yet well understood. Here, the advection and diffusion of buoyant particles were modeled with a large eddy simulation. Advection speed and effective diffusivity were quantitatively compared based on the evolution of the particles' statistical quantities. When the vertical dispersion of the buoyant particles was enhanced by LC, the horizontal dispersion increased, and the horizontal advection decreased. WB had a noticeable influence on the particles leaving the surface. Strongly buoyant particles slightly dispersed but advected as fast as the surface velocities. Weakly buoyant particles dispersed extensively but advected quite slowly. Sparse observations in the East/Japan Sea (EJS) suggested that open-ocean deep convection occurs south of Vladivostok; however, more recent observations suggest that deep convection occurs along the continental slope, resulting in bottom water formation in the EJS. The process of deep convection along the EJS continental slope was investigated using large-eddy simulation, which demonstrated that dense water, formed by strong wintertime cooling in the shelf, flows down along the slope as a bottom Ekman current. The characteristics of the initial dense water were relatively well conserved on the continental slope during convection, but they changed rapidly by mixing with the surrounding waters in the open ocean. Accordingly, slope convection penetrated deeper compared to open-ocean convection under the same surface heat flux. Our numerical experiments showed that, under typical surface cooling during winter (i.e., 200 W m-2), slope convection reaches depths greater than 2,700 m, generating a potential ventilation process for deep- and bottom-water formations, whereas open-ocean convection reaches approximately 700 m depth, contributing to the intermediate- and central-water formations in the EJS. Various topography experiments revealed that downward speed was proportional to the continental-slope inclination; the initial characteristics remained relatively well conserved at small continental-slope inclination. Increased salinity due to brine rejection in the shelf could accelerate the slope convection.큰에디모사기법(LES)를 이용하여 한국 주변의 난류 해양 현상을 모의하고 그 특성을 조사하였다. 대부분의 심각한 해양 유출 사고는 강풍 중에 발생하며 오염 물질의 확산은 랑뮤어 순환(LC) 및 파도 깨짐(WB)과 같은 파랑 기반의 해양 상부 난류에 따라 달라진다. 그러나 LC와 WB가 이류 속도와 확산 속도에 미치는 영향은 아직 잘 알려져 있지 않다. 본 연구에서 부력 입자의 이류 및 확산을 LES로 모델링하였다. 입자의 통계적 양의 변화를 기반으로 이류 속도와 유효 확산도를 정량적으로 비교하였다. 부력입자의 수직분산이 LC에 의해 강화되었을 때 수평분산은 증가하였고 수평이류는 감소하였다. WB는 입자가 표면을 떠나도록 하여 상당한 영향을 미쳤다. 부력이 강한 입자는 약하게 분산되지만 표면 속도로 빠르게 이류하였다. 약한 부력 입자는 광범위하게 분산되지만 아주 천천히 이류하였다. 최근 동해(EJS)에서의 관측은 블라디보스토크 남쪽에서 대륙 사면을 따라 심층 대류가 발생하여 저층수가 형성됨을 시사했다. 본 연구에서 대륙 사면을 따른 심층 대류 과정은 큰에디모사기법을 사용하여 조사되었으며, 이는 대륙붕에서 겨울철 강한 냉각에 의해 형성된 밀도가 높은 물이 바닥 에크만 해류로 사면을 따라 흘러내리는 것을 보여주었다. 대륙사면을 따르는 심층 대류의 경우는 고밀도 해수의 특성이 침강하는 동안 비교적 잘 보존되었으나, 외해에서 발생한 대류의 경우는 주변해역과 혼합되면서 특성을 잃었다. 따라서 동일한 표면 열속 조건에서 사면 대류(Slope Convection)는 외양 대류(Open-ocean Convection)에 비해 더 깊게 침투하였다. 겨울철의 전형적인 표면 냉각(200W m-2) 조건에서 사면 대류는 2,700m 이상의 깊이에 도달하여 심층 및 저층에 대한 잠재적인 순환 과정을 형성하였다. 반면 외양 대류는 최대 약 700m 깊이에 도달하여 동해의 중층수 및 중앙수 형성에 기여함을 보였다. 다양한 지형 실험에서 침강 속도는 대륙 사면의 경사에 비례한다는 것이 밝혀졌다. 고밀도수의 초기 특성은 경사가 작을 때 비교적 잘 보존되었다. 대륙붕 내부의 염 방출로 인한 염분 증가는 사면 대류를 가속화할 수 있다.Abstract i Table of Contents iii List of Figures vi List of Tables xi 1. General Introduction 1 1.1. Modeling oceanic turbulence 1 1.2. Large-eddy simulation model 3 2. Effect of Wave-Driven Turbulence on Diffusion and Advection of Pollutants 6 2.1. Introduction 6 2.2. Methods 9 2.2.1. Numerical modeling 9 2.2.2. Simulation configurations 11 2.3. Results 12 2.3.1. Mean profiles of velocity and turbulent kinetic energy 12 2.3.2. Horizontal and vertical distributions of the particles 14 2.3.3. Vertical and horizontal dispersion of particles and effective diffusivity 15 2.3.4. Horizontal advection of particles 17 2.4. Discussion 18 2.4.1. Cause of the difference in horizontal dispersion and advection 18 2.4.2. Estimation of advection speed 19 2.4.3. Diffusion and advection influenced by rising speed 20 2.4.4. Sensitivity to the model domain size 21 2.5. Conclusion 22 3. Deep Convection in the East Sea 34 3.1. Introduction 34 3.2. Materials and methods 36 3.3. Open-ocean and slope convections 39 3.3.1. Convection evolution 39 3.3.2. Horizontal distributions of vertical velocity 42 3.3.3. Meridional sections of zonal-mean velocity 44 3.4. Discussion 46 3.4.1. Role of the continental shelf on slope convection 46 3.4.2. Effect of the continental-slope inclination on slope convection 47 3.4.3. Effect of brine rejection on the slope convection 49 3.5. Conclusion 50 4. Summary and Conclusions 67 Bibliography 69 Abstract in Korean (국문초록) 79 Acknowledgments 81박

Assessing the Real-Time Lagrangian Predictability of the Operational Navy Coastal Ocean Model in the Gulf of Mexico

This study quantitatively assesses the drift predictive skill of Fleet Numerical Meteorology and Oceanography Center’s (FNMOC’s) operational ocean models which are used to support a wide range of military and civilian applications. Overall, the findings of this work support the recommendation of spatial filtering for regional-scale ocean model velocity fields used in deep-water drift applications. In conjunction with filtering, the use of a pure particle drift algorithm is suggested for short-term forecasts and a drift algorithm including a sub-grid scale, random flight, parameterization for predictions requiring extended forecast predictions. Drift prediction skill is quantified through metrics of in-cloud percentage, distance error, and cloud size, which are used to assess the impact of different drift algorithms and underlying ocean models on the drift prediction capability. Through an exploration of parameterization additions to the drift algorithm, spatial filtering of model velocity fields, and increases in model horizontal resolution, drift prediction skill is shown to be counter-balanced on the accuracy of the model\u27s dispersive characteristics along with the accuracy of the underlying model velocity field (i.e. data-constrained, predictable features). A regional scale model at a horizontal resolution typically employed by FNMOC (3-kilometers) is found to be grossly under dispersive, and derived drift predictions using a pure particle algorithm are not skillful in terms of in-cloud percentage beyond a 24-hour forecast. Parameterization additions (i.e. sub-grid scale velocity and Leeway), which enhance model dispersion, are shown to greatly improve the regional scale model\u27s ability to predict a drift cloud that encompasses an object of interest at longer forecast lengths (\u3e 24-hours) by increasing cloud size. Increasing the model’s horizontal resolution (500-meters) is likewise shown to improve in-cloud prediction performance at all forecast lengths, due to its more accurate representation of dispersion which results in much larger cloud size predictions compared to those from a regional scale model. Spatial filtering of regional scale velocity fields using a Gaussian filter removes uncertain, unpredictable features (i.e. submesocale) leaving behind a data-constrained velocity field. Even though spatial filtering suppresses dispersion further for an already under-dispersion regional scale model, filtering is shown to significantly improve drift prediction performance extending in-cloud skill farther into the forecast, reducing distance errors by 15-20%, and reducing cloud size predictions by 20-30%

Marine oil spill simulation and uncertainty analysis - a case study in the Newfoundland offshore area

Oil spills have been regarded as one of the major contributors to marine pollution. With the rapidly changing environmental conditions and the diverse uncertainties in the data associated with the observation or meteorological and oceanographic data, the simulation of an oil spill is challenging to be accurate and reliable enough for supporting response management. Furthermore, with the different assumptions, structures and translations of various simulation models, results could significantly vary even with the same inputs. The objectives of this research are therefore 1) to compare three widely used models for offshore oil spill simulation and evaluate their capabilities under harsh environmental conditions; and 2) to develop a Design of Experiment (DOE) based approach for analyzing uncertainties associated with the spill modeling input and parameters to help improve offshore oil spill simulation. In this research, the Terra Nova oil spill occurred on November 21, 2004, the largest oil spill in offshore Newfoundland, was chosen as a case study. The models, namely GNOME/ADIOS2 and OSCAR, were employed for the simulation of fate and transport of the spilled oil. During the simulation, ocean currents data from the Hybrid Coordinate Ocean Model (HYCOM) and surface wind data measured by the National Climate Data Center (NCDC) were used. The simulation results indicated that 43.7% of the spilled oil evaporated or dispersed in the first two days. With the model of OSCAR, 87.4% of the total spilled oil was evaporated or dispersed, while 10.8% was biodegraded. Only 1.6% of oil remained on the sea surface after six days, which agreed well with the historical data. The results from GNOME showed a more reasonable match with the observations from the RADARSAT-1 satellite images regarding the spill plume, shape and location as compared to those from OSCAR. But on the other hand, OSCAR showed better performance in simulating weathering process. To facilitate a better understanding of the oil fate and transport, and to improve simulation performance, a DOE aided method was developed for sensitivity analysis, parameter calibration and interaction analysis of key factors during spill simulation. The interactions between wind speed and direction, and the currents have been analyzed and the effects of their interactions have been studied. In this case study, the key factors “Windage” and “Wind speed scale” both had the negative effects on the modeling response, but their interaction showed positive effects. The “Along current uncertainty” and “Diffusion coefficient” caused the negative and positive effects, respectively, but leading to the positive effects by their interaction. The results indicated that when adjusting the primary factors in order to optimize the response, interactions between factors may lead an opposite way and missed the optimal solution. The validation through the case study showed consistency with high values of R² (e.g., 0.93 and 0.95 for deviations of coverage and distance between the observed and simulated spills respectively). The results indicated that this DOE aided parameterization method could potentially be a useful tool for the evaluation of the contribution of multiple parameters and be applied as a new calibration method for other oil spill simulation models