scholarly journals Performance Comparisons on Parallel Optimization of Atmospheric and Ocean Numerical Circulation Models Using KISTI Supercomputer Nurion System

2020 ◽  
Vol 10 (8) ◽  
pp. 2883
Author(s):  
Chaewook Lim ◽  
Dong-Hoon Kim ◽  
Seung-Buhm Woo ◽  
Minsu Joh ◽  
Jooneun An ◽  
...  
Keyword(s):  
High Resolution ◽  
Ocean Model ◽  
Performance Comparison ◽  
Ocean Modeling ◽  
Parallel Optimization ◽  
Weather Research And Forecasting ◽  
Regional Ocean Modeling System ◽  
Multicore System ◽  
Forecasting System ◽  
Performance Rate

The characteristics of the 5th Supercomputer Nurion Knights Landing (KNL) system of the Korea Institute of Science and Technology Information (KISTI) were analyzed by developing ultra-high resolution atmospheric and ocean numerical circulation models. These models include the Weather Research and Forecasting System (WRF), Regional Ocean Modeling System (ROMS), and Unstructured Grid Finite Volume Community Ocean Model (FVCOM). Ideal and real-case experiments were simulated for each model according to the number of parallelized cores used for comparing performances. Identical experiments were performed on a general multicore system (Skylake and a general cluster system) for a performance comparison with the Nurion KNL system. Although the KNL system has more than twice as many cores per node as the Skylake system, the KNL system demonstrated 1/3 of the performance rate of the Skylake system. However, the performance rate of the Nurion KNL system was approximately 43% for all experiments. Reducing the number of cores per node in the KNL system by half (36 cores) is the most efficient method when the total number of cores is less than 256 cores, while it is more economical to use all cores when using more than 256 cores. In all experiments, the performance was continuously improved even for a maximum core experiment (1024 cores), thereby indicating that the KNL system can effectively simulate ultra-high resolution numerical circulation models.

scholarly journals Multi-Physics Ensemble versus Atmosphere–Ocean Coupled Model Simulations for a Tropical-Like Cyclone in the Mediterranean Sea

Atmosphere ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 202 ◽  
Author(s):  
Antonio Ricchi ◽  
Mario Marcello Miglietta ◽  
Davide Bonaldo ◽  
Guido Cioni ◽  
Umberto Rizza ◽  
...  
Keyword(s):  
High Resolution ◽  
Mediterranean Sea ◽  
Computational Cost ◽  
Ocean Model ◽  
Surface Fluxes ◽  
Ocean Modeling ◽  
Sea Surface ◽  
Regional Ocean Modeling System ◽  
The Mediterranean ◽  
Physics Ensemble

Between 19 and 22 January 2014, a baroclinic wave moving eastward from the Atlantic Ocean generated a cut-off low over the Strait of Gibraltar and was responsible for the subsequent intensification of an extra-tropical cyclone. This system exhibited tropical-like features in the following stages of its life cycle and remained active for approximately 80 h, moving along the Mediterranean Sea from west to east, eventually reaching the Adriatic Sea. Two different modeling approaches, which are comparable in terms of computational cost, are analyzed here to represent the cyclone evolution. First, a multi-physics ensemble using different microphysics and turbulence parameterization schemes available in the WRF (weather research and forecasting) model is employed. Second, the COAWST (coupled ocean–atmosphere wave sediment transport modeling system) suite, including WRF as an atmospheric model, ROMS (regional ocean modeling system) as an ocean model, and SWAN (simulating waves in nearshore) as a wave model, is used. The advantage of using a coupled modeling system is evaluated taking into account air–sea interaction processes at growing levels of complexity. First, a high-resolution sea surface temperature (SST) field, updated every 6 h, is used to force a WRF model stand-alone atmospheric simulation. Later, a two-way atmosphere–ocean coupled configuration is employed using COAWST, where SST is updated using consistent sea surface fluxes in the atmospheric and ocean models. Results show that a 1D ocean model is able to reproduce the evolution of the cyclone rather well, given a high-resolution initial SST field produced by ROMS after a long spin-up time. Additionally, coupled simulations reproduce more accurate (less intense) sea surface heat fluxes and a cyclone track and intensity, compared with a multi-physics ensemble of standalone atmospheric simulations.

Predicting Surface Oil Transport in California Using a High-Resolution Regional Ocean Modeling System (ROMS) and the National Oceanic and Atmospheric Administration's (NOAA's) Trajectory Analysis Planner (TAP)

2017 ◽  
Vol 2017 (1) ◽  
pp. 2017309
Author(s):  
S. F. Zaleski ◽  
G. Watabayashi ◽  
C. Dong ◽  
C. H. Barker ◽  
A. MacFadyen ◽  
...  
Keyword(s):  
High Resolution ◽  
Los Angeles ◽  
Oil Spill ◽  
Southern California ◽  
Ocean Model ◽  
Ocean Modeling ◽  
Regional Ocean Modeling System ◽  
Response Planning ◽  
Spilled Oil

The Bureau of Ocean Energy Management (BOEM) and Bureau of Safety and Environmental Enforcement (BSEE) Pacific Region conduct oil spill risk analyses to determine potential impacts to environmental resources. Oil spill trajectory modeling is conducted to predict the movement and fate of spilled oil, if a spill occurred, from existing offshore oil and gas operations in southern California. To improve BOEM and BSEE Pacific Region's ability to conduct oil spill risk analyses for southern California, BOEM partnered with the University of California, Los Angeles (UCLA) to run a multi-year hind cast (re-analysis) of winds, waves, and currents along the coast of California. UCLA created a high-resolution (1 km) ROMS hind cast for the 10 year period 2004–2013 from Morro Bay, California to the border with Mexico. The project was conducted in three phases: (1) Surface winds were calculated at high horizontal and temporal resolution and validated using existing datasets; (2) A wave model was forced by the wind model results and validated through in situ measurements; and (3) The ocean model was run at high resolution and includes temperature, salinity, and currents; it assimilated in situ data and was forced by the hind cast atmospheric model results. BOEM is subsequently partnering with NOAA, to utilize the surface currents and winds from the ROMS hind cast analysis with NOAA's General NOAA Operational Modeling Environment (GNOME) to produce multiple trajectories for NOAA's TAP. Using realistic oil spill scenarios over a range of different regional oceanographic regimes (such as upwelling, relaxation, and eddy-driven flow), TAP will calculate the probabilities of oil contacting parcels of water and shoreline were any oil to spill from southern California oil platforms. This will enable analysts to understand where an oil spill may travel, how long it could take to get there, and the likelihood of spilled oil contacting their resource area. An online TAP viewer with the GNOME-generated data from this study will be publicly available along with the ROMS hind cast data for oil spill response planning along with other oceanographic modeling needs.

scholarly journals Permanent Meanders in the California Current System

2008 ◽  
Vol 38 (8) ◽  
pp. 1690-1710 ◽  
Author(s):  
L. R. Centurioni ◽  
J. C. Ohlmann ◽  
P. P. Niiler
Keyword(s):  
Sea Level ◽  
Current System ◽  
California Current ◽  
Ocean Model ◽  
Ocean Modeling ◽  
Surface Velocity ◽  
Regional Ocean Modeling System ◽  
Near Surface ◽  
Geostrophic Velocity ◽  
California Current System

Abstract Surface Velocity Program (SVP) drifter data from 1987 through 2005; Archiving, Validation, and Interpretation of Satellite Oceanographic data (AVISO) sea level anomalies; and NCEP reanalysis winds are used to assemble a time-averaged map of the 15-m-deep geostrophic velocity field in the California Current System seaward of about 50 km from the coast. The wind data are used to compute the Ekman currents, which are then subtracted from the drifter velocity measurements. The resulting proxy for geostrophic velocity anomalies computed from drifters and from satellite sea level measurements are combined to form an unbiased mean geostrophic circulation map. The result shows a California Current System that flows southward with four permanent meanders that can extend seaward for more than 800 km. Bands of alternating eastward and westward zonal currents are connected to the meanders and extend several thousand kilometers into the Pacific Ocean. This observed time-mean circulation and its associated eddy energy are compared to those produced by various high-resolution OGCM solutions: Regional Ocean Modeling System (ROMS; 5 km), Parallel Ocean Program model (POP; 1/10°), Hybrid Coordinate Ocean Model (HYCOM; 1/12°), and Naval Research Laboratory (NRL) Layered Ocean Model (NLOM; 1/32°). Simulations in closest agreement with observations come from ROMS, which also produces four meanders, geostrophic time-mean currents, and geostrophic eddy energy consistent with the observed values. The time-mean ageostrophic velocity in ROMS is strongest within the cyclonic part of the meanders and is similar to the ageostrophic velocity produced by nonlinear interaction of Ekman currents with the near-surface vorticity field.

scholarly journals Impacts of the Madden–Julian Oscillation on the Summer South China Sea Ocean Circulation and Temperature

2013 ◽  
Vol 26 (20) ◽  
pp. 8084-8096 ◽  
Author(s):  
Guihua Wang ◽  
Zheng Ling ◽  
Renguang Wu ◽  
Changlin Chen
Keyword(s):  
South China Sea ◽  
Ocean Circulation ◽  
South China ◽  
Ocean Model ◽  
Ocean Modeling ◽  
Madden Julian Oscillation ◽  
Regional Ocean Modeling System ◽  
Wind Stress Curl ◽  
China Sea ◽  
The Impact

Abstract The present study investigates the impact of the Madden–Julian oscillation (MJO) on the South China Sea (SCS) in summer with three types of models: a theoretical Sverdrup model, a 1.5-layer reduced gravity model, and a regional ocean model [Regional Ocean Modeling System (ROMS)]. Results show that the ocean circulation in the SCS has an intraseasonal oscillation responding to the MJO. During its westerly phase, the MJO produces positive (negative) wind stress curl over the northern (southern) SCS and thus induces an enhanced cyclonic (anticyclonic) circulation in the northern (southern) SCS. This not only cools sea surface temperature (SST) but also decreases (increases) subsurface temperature in the northern (southern) SCS. During its easterly phase, the MJO basically produces a reversed but weaker influence on SCS ocean circulation and temperature. Thus, the MJO can have an imprint on the summer climatology of SCS circulation and temperature. The authors' analysis further indicates that the MJO's dynamic effect associated with wind is generally more important than its thermodynamic effect in modulating the regional ocean circulation and temperature. The present study suggests that the MJO is important for summer ocean circulation and temperature in the SCS.

scholarly journals High resolution nested model for the Cyprus, NE Levantine Basin, eastern Mediterranean Sea: implementation and climatological runs

2003 ◽  
Vol 21 (1) ◽  
pp. 221-236 ◽  
Author(s):  
G. Zodiatis ◽  
R. Lardner ◽  
A. Lascaratos ◽  
G. Georgiou ◽  
G. Korres ◽  
...  
Keyword(s):  
High Resolution ◽  
Mediterranean Sea ◽  
General Circulation ◽  
Eastern Mediterranean ◽  
Pilot Project ◽  
Ocean Model ◽  
Eastern Mediterranean Sea ◽  
Coastal Shelf ◽  
Forecasting System ◽  
The Mediterranean

Abstract. A high resolution nested flow model for the coastal, shelf and open sea areas of the Cyprus Basin, NE Levantine, eastern Mediterranean Sea is implemented to fulfil the objectives of the Mediterranean Forecasting System Pilot Project, funded by the EU. The Cyprus coastal ocean model is nested entirely within a coarse regional grid model of the eastern Mediterranean Sea, using the MODB climatology for initialisation and the ECMWF perpetual year surface forcing. The nested simulations of the Cyprus model were able to reproduce, with greater detail, flow features similar to those of the coarse grid regional model. The project results show the feasibility of the approach for the development of an operational forecasting system in the Mediterranean Sea, particularly in the Cyprus coastal/shelf sea area. Key words. Oceanography: general (descriptive and regional oceanography; numerical modelling) Oceanography: physical (general circulation)

scholarly journals High-Resolution Operational Ocean Forecast and Reanalysis System for the Indian Ocean

2020 ◽  
Vol 101 (8) ◽  
pp. E1340-E1356 ◽  
Author(s):  
P. A. Francis ◽  
A. K. Jithin ◽  
J. B. Effy ◽  
A. Chatterjee ◽  
K. Chakraborty ◽  
...  
Keyword(s):  
High Resolution ◽  
Indian Ocean ◽  
Data Assimilation ◽  
Coastal Waters ◽  
General Circulation ◽  
High Performance ◽  
Coast Guard ◽  
Ocean Modeling ◽  
Regional Ocean Modeling System ◽  
The Indian Ocean

Abstract A good understanding of the general circulation features of the oceans, particularly of the coastal waters, and ability to predict the key oceanographic parameters with good accuracy and sufficient lead time are necessary for the safe conduct of maritime activities such as fishing, shipping, and offshore industries. Considering these requirements and buoyed by the advancements in the field of ocean modeling, data assimilation, and ocean observation networks along with the availability of the high-performance computational facility in India, Indian National Centre for Ocean Information Services has set up a “High-Resolution Operational Ocean Forecast and Reanalysis System” (HOOFS) with an aim to provide accurate ocean analysis and forecasts for the public, researchers, and other types of users like navigators and the Indian Coast Guard. Major components of HOOFS are (i) a suite of numerical ocean models configured for the Indian Ocean and the coastal waters using the Regional Ocean Modeling System (ROMS) for forecasting physical and biogeochemical state of the ocean and (ii) the data assimilation based on local ensemble transform Kalman filter that assimilates in situ and satellite observations in ROMS. Apart from the routine forecasts of key oceanographic parameters, a few important applications such as (i) Potential Fishing Zone forecasting system and (ii) Search and Rescue Aid Tool are also developed as part of the HOOFS project. The architecture of HOOFS, an account of the quality of ocean analysis and forecasts produced by it and important applications developed based on HOOFS are briefly discussed in this article.

The Nonlinear Optimal Triggering Perturbation of the Kuroshio Large Meander and Its Evolution in a Regional Ocean Model

2018 ◽  
Vol 48 (8) ◽  
pp. 1771-1786 ◽  
Author(s):  
Xia Liu ◽  
Mu Mu ◽  
Qiang Wang
Keyword(s):  
Ocean Model ◽  
Ocean Modeling ◽  
Cyclonic Eddy ◽  
Regional Ocean Modeling System ◽  
Large Meander ◽  
Optimal Perturbation ◽  
Nonlinear Advection ◽  
Kuroshio Large Meander ◽  
Opposing Effects ◽  
The Kuroshio

AbstractBased on the Regional Ocean Modeling System (ROMS) and the conditional nonlinear optimal perturbation (CNOP) method, we explore the nonlinear optimal triggering perturbation of the Kuroshio large meander (LM) and its evolution, and reveal the role of nonlinear physical processes in the formation of the LM path. The results show that the large amplitudes of the perturbations are mainly located in the upper 2000 m in the southeastern area of Kyushu (29°–32°N, 131°–134°E), where the eastward propagation of the cold anomaly is vital to the formation of the LM path. By analyzing the depth-integrated vorticity equation of the perturbation, we find that linear advection, namely, the interaction between the perturbation and the reference field, tends to move the cyclonic eddy induced by the optimal triggering perturbation eastward, while the nonlinear advection associated with the interaction of perturbations tends to move the cyclonic eddy westward. The opposing effects of the nonlinear advection and the linear advection slow the eastward movement of the cyclonic eddy so that the eddy has a chance to effectively develop, eventually leading to the formation of the Kuroshio LM path.

Seasonality of Submesoscale processes in the Bay of Bengal

2020 ◽  
Author(s):  
Lanman Li ◽  
Xuhua Cheng
Keyword(s):  
High Resolution ◽  
Mixed Layer ◽  
Bay Of Bengal ◽  
Gulf Stream ◽  
Strain Field ◽  
Mesoscale Eddies ◽  
Ocean Modeling ◽  
Small Scale ◽  
Regional Ocean Modeling System ◽  
Submesoscale Processes

<p>Mesoscale eddies that known as a dominant reservoir of kinetic energy has been studied extensively for its dynamics and variation.In order to maintain energy budget equilibrium,the energy stored in mesoscale eddies is dissipated by small scale processes around centimeters.Submesoscale processes that lie between mesoscale and microscale motions effectively extract energy from mesoscale motions and transfer to smaller scales.The Bay of Bengal(the BOB) receives large fresh water from precipitation and river runoff resulting in strong salinity fronts that conducive to the generation of submesoscale processes.Using the Regional Ocean Modeling System(ROMS) data with two horizontal resolutions:a high-resolution(~1.6km) that is partially resolve submesoscale,and a low-resolution(~7km) that not resolves submesoscale,we focus on the seasonality of submesoscale processes in the Bay of Bengal.To ensure that only the submesoscale motions is considered,we choose 40km as the length to separate submesoscale from the flow field.Results show that submesocale processes is ubiquitous in the BOB,mainly trapped in the mixed layer.As resolution increasing,submesoscale motions become much stronger.Seasonality of submesoscale in the BOB is apparent and is different from the Gulf stream region  which is strongest in winter and weakest in summer.Submesoscale features in this region mostly present in fall,which the most important mechanisms is frontogenesis due to strong horizontal buoyancy flux associated with large strain.Submesoscale motions is also vigorous in winter.The proposed mechanism is that the depth of mixed layer is deep enough which contributes to the occurrence of mixed layer instability.During the whole year,mesoscale strain field is weakest in summer,which makes submesoscale weakest.</p>

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