EnOI-Based Data Assimilation Technology for Satellite Observations and ARGO Float Measurements in a High Resolution Global Ocean Model Using the CMF Platform

2016 ◽  
pp. 57-66 ◽  
Author(s):  
Maxim Kaurkin ◽  
Rashit Ibrayev ◽  
Alexandr Koromyslov
Keyword(s):  
High Resolution ◽  
Data Assimilation ◽  
Ocean Model ◽  
Satellite Observations ◽  
Global Ocean ◽  
Argo Float

Evaluating Effects of Observational Data Assimilation in General Ocean Circulation Model by Ensemble Kalman Filtering: Numerical Experiments with Synthetic Observations

2021 ◽  
pp. 50-66
Author(s):  
V. N. Stepanov ◽  
◽  
Yu. D. Resnyanskii ◽  
B. S. Strukov ◽  
A. A. Zelen’ko ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Observational Data ◽  
Ocean Circulation ◽  
Numerical Experiments ◽  
Turbulent Viscosity ◽  
Bottom Topography ◽  
Synthetic Data ◽  
Circulation Model ◽  
Ocean Model ◽  
Global Ocean

The quality of simulation of model fields is analyzed depending on the assimilation of various types of data using the PDAF software product assimilating synthetic data into the NEMO global ocean model. Several numerical experiments are performed to simulate the ocean–sea ice system. Initially, free model was run with different values of the coefficients of horizontal turbulent viscosity and diffusion, but with the same atmospheric forcing. The model output obtained with higher values of these coefficients was used to determine the first guess fields in subsequent experiments with data assimilation, while the model results with lower values of the coefficients were assumed to be true states, and a part of these results was used as synthetic observations. The results are analyzed that are assimilation of various types of observational data using the Kalman filter included through the PDAF to the NEMO model with real bottom topography. It is shown that a degree of improving model fields in the process of data assimilation is highly dependent on the structure of data at the input of the assimilation procedure.

A new method for characterising the Antarctic Circumpolar Currents using Argo float temperature and salinity profiles

2020 ◽  
Author(s):  
Luke Roberts ◽  
Rhiannon Jones ◽  
Matthew Donnelly ◽  
Katharine Hendry
Keyword(s):  
High Resolution ◽  
Southern Ocean ◽  
Data Processing ◽  
Rapid Development ◽  
Regional Scale ◽  
Global Ocean ◽  
Argo Float ◽  
Oceanographic Data ◽  
The University ◽  
The Antarctic

<p>Argo is an array of automated profiling floats, which have allowed the rapid development of high-resolution and high-quality oceanographic data acquisition. The international program has been in operation since the 1990s providing continuous hydrographic data globally. There are now over a million individual float profiles, contributing to our understanding of global ocean physical properties, such as circulation processes at both a local and regional scale. With these innovations come the challenges of data processing, and compilation of user-friendly data products. For example, the Southern Ocean is a critical region that modulates our climate, via heat exchange, carbon storage, biogeochemistry, and primary productivity. An improved quantified understanding of Southern Ocean currents, informed by Argo, must be implemented in policy-relevant high-resolution climate models to advance our understanding of future change.</p><p> </p><p>In May 2019, a new collaboration was formed between the Southern Ocean Argo Resource Centre (British Oceanographic Data Centre) and the University of Bristol. The aims were two-fold: to produce a method for characterising Southern Ocean frontal zones using Argo floats, and to train early career researchers in the University sector in data processing and management. We have created a publicly available code that characterises physical features of the Antarctic Circumpolar Current using Argo float profiles, using minimal software, and without the need to access high-performance computers. The code categorises each profile based on the temperature and salinity ‘fingerprints’ of zones between each Southern Ocean front. This allows the user to produce output surface plots from user-specified time-slices and geographic areas, and so compare frontal movement in time and space.</p>

scholarly journals P-CSI v1.0, an accelerated barotropic solver for the high-resolution ocean model component in the Community Earth System Model v2.0

2016 ◽  
Vol 9 (11) ◽  
pp. 4209-4225 ◽  
Author(s):  
Xiaomeng Huang ◽  
Qiang Tang ◽  
Yuheng Tseng ◽  
Yong Hu ◽  
Allison H. Baker ◽  
...  
Keyword(s):  
High Resolution ◽  
Ocean Model ◽  
Original Method ◽  
Earth System Model ◽  
System Model ◽  
Global Ocean ◽  
Global Communication ◽  
Earth System ◽  
Communication Time ◽  
Community Earth System Model

Abstract. In the Community Earth System Model (CESM), the ocean model is computationally expensive for high-resolution grids and is often the least scalable component for high-resolution production experiments. The major bottleneck is that the barotropic solver scales poorly at high core counts. We design a new barotropic solver to accelerate the high-resolution ocean simulation. The novel solver adopts a Chebyshev-type iterative method to reduce the global communication cost in conjunction with an effective block preconditioner to further reduce the iterations. The algorithm and its computational complexity are theoretically analyzed and compared with other existing methods. We confirm the significant reduction of the global communication time with a competitive convergence rate using a series of idealized tests. Numerical experiments using the CESM 0.1° global ocean model show that the proposed approach results in a factor of 1.7 speed-up over the original method with no loss of accuracy, achieving 10.5 simulated years per wall-clock day on 16 875 cores.

scholarly journals Improved Turbulent Air–Sea Flux Bulk Parameters for Controlling the Response of the Ocean Mixed Layer: A Sequential Data Assimilation Approach

2009 ◽  
Vol 26 (3) ◽  
pp. 538-555 ◽  
Author(s):  
Sergey Skachko ◽  
Jean-Michel Brankart ◽  
Frédéric Castruccio ◽  
Pierre Brasseur ◽  
Jacques Verron
Keyword(s):  
Heat Flux ◽  
Data Assimilation ◽  
Mixed Layer ◽  
Sensible Heat Flux ◽  
Ocean Model ◽  
Global Ocean ◽  
Model Parameters ◽  
Sequential Data ◽  
Bulk Parameters ◽  
Sequential Data Assimilation

Abstract Bulk formulations parameterizing turbulent air–sea fluxes remain among the main sources of error in present-day ocean models. The objective of this study is to investigate the possibility of estimating the turbulent bulk exchange coefficients using sequential data assimilation. It is expected that existing ocean assimilation systems can use this method to improve the air–sea fluxes and produce more realistic forecasts of the thermohaline characteristics of the mixed layer. The method involves augmenting the control vector of the assimilation scheme using the model parameters that are to be controlled. The focus of this research is on estimating two bulk coefficients that drive the sensible heat flux, the latent heat flux, and the evaporation flux of a global ocean model, by assimilating temperature and salinity profiles using horizontal and temporal samplings similar to those to be provided by the Argo float system. The results of twin experiments show that the method is able to correctly estimate the large-scale variations in the bulk parameters, leading to a significant improvement in the atmospheric forcing applied to the ocean model.

scholarly journals Performance and results of the high-resolution biogeochemical model PELAGOS025 v1.0 within NEMO v3.4

2016 ◽  
Vol 9 (6) ◽  
pp. 2115-2128 ◽  
Author(s):  
Italo Epicoco ◽  
Silvia Mocavero ◽  
Francesca Macchia ◽  
Marcello Vichi ◽  
Tomas Lovato ◽  
...  
Keyword(s):  
High Resolution ◽  
Message Passing ◽  
Ocean Model ◽  
Parallel Architectures ◽  
Global Ocean ◽  
Biogeochemical Model ◽  
Memory Contention ◽  
On Line ◽  
Flux Model ◽  
Line Coupling

Abstract. The present work aims at evaluating the scalability performance of a high-resolution global ocean biogeochemistry model (PELAGOS025) on massive parallel architectures and the benefits in terms of the time-to-solution reduction. PELAGOS025 is an on-line coupling between the Nucleus for the European Modelling of the Ocean (NEMO) physical ocean model and the Biogeochemical Flux Model (BFM) biogeochemical model. Both the models use a parallel domain decomposition along the horizontal dimension. The parallelisation is based on the message passing paradigm. The performance analysis has been done on two parallel architectures, an IBM BlueGene/Q at ALCF (Argonne Leadership Computing Facilities) and an IBM iDataPlex with Sandy Bridge processors at the CMCC (Euro Mediterranean Center on Climate Change). The outcome of the analysis demonstrated that the lack of scalability is due to several factors such as the I/O operations, the memory contention, the load unbalancing due to the memory structure of the BFM component and, for the BlueGene/Q, the absence of a hybrid parallelisation approach.

scholarly journals Assimilation of Middepth Velocities from Argo Floats in the Western South China Sea

2020 ◽  
Vol 37 (1) ◽  
pp. 141-157
Author(s):  
Pinqiang Wang ◽  
Weimin Zhang ◽  
Huizan Wang ◽  
Haijin Dai ◽  
Xiaohui Wang
Keyword(s):  
Data Assimilation ◽  
South China Sea ◽  
South China ◽  
Ocean Model ◽  
Trajectory Data ◽  
Argo Float ◽  
Argo Floats ◽  
China Sea ◽  
Regional Ocean Model System ◽  
Regional Ocean Model

AbstractPrevious studies are mainly limited to temperature and salinity (T/S) profiling data assimilation, while data assimilation based on Argo float trajectory information has received less research focus. In this study, a new method was proposed to assimilate Argo trajectory data: the middepth (indicates the parking depth of Argo floats in this study, ~1200 m) velocities are estimated from Argo trajectories and subsequently assimilated into the Regional Ocean Model System (ROMS) using four-dimensional variational data assimilation (4DVAR) method. This method can avoid a complicated float trajectory model in direct position assimilation. The 2-month assimilation experiments in South China Sea (SCS) showed that this proposed method can effectively assimilate Argo trajectory information into the model and improve middepth velocity field by adjusting the unbalanced component in the velocity increments. The assimilation of the Argo trajectory-derived middepth velocity with other observations (satellite observations and T/S profiling data) together yielded the best performance, and the velocity fields at the float parking depth are more consistent with the Argo float trajectories. In addition, this method will not decrease the assimilation performance of other observations [i.e., sea level anomaly (SLA), sea surface temperature (SST), and T/S profiles], which is indicative of compatibility with other observations in the 4DVAR assimilation system.

scholarly journals Impact of horizontal resolution on global ocean-sea-ice model simulations based on the experimental protocols of the Ocean Model Intercomparison Project phase 2 (OMIP-2)

2020 ◽  
Author(s):  
Eric P. Chassignet ◽  
Stephen G. Yeager ◽  
Baylor Fox-Kemper ◽  
Alexandra Bozec ◽  
Fred Castruccio ◽  
...  
Keyword(s):  
High Resolution ◽  
Sea Ice ◽  
Global Climate ◽  
Horizontal Resolution ◽  
Ocean Model ◽  
Global Ocean ◽  
Western Boundary ◽  
Low Resolution ◽  
Circumpolar Current ◽  
High Resolution Models

Abstract. This paper presents global comparisons of fundamental global climate variables from a suite of four pairs of matched low- and high-resolution ocean and sea-ice simulations that are obtained following the OMIP-2 protocol (Griffies et al., 2016) and integrated for one cycle (1958–2018) of the JRA55-do atmospheric state and runoff dataset (Tsujino et al., 2018). Our goal is to assess the robustness of climate-relevant improvements in ocean simulations (mean and variability) associated with moving from coarse (~ 1º) to eddy-resolving (~ 0.1º) horizontal resolutions. The models are diverse in their numerics and parameterizations, but each low-resolution and high-resolution pair of models is matched so as to isolate, to the extent possible, the effects of horizontal resolution. A variety of observational datasets are used to assess the fidelity of simulated temperature and salinity, sea surface height, kinetic energy, heat and volume transports, and sea ice distribution. This paper provides a crucial benchmark for future studies comparing and improving different schemes in any of the models used in this study or similar ones. The biases in the low-resolution simulations are familiar and their gross features – position, strength, and variability of western boundary currents, equatorial currents, and Antarctic Circumpolar Current – are significantly improved in the high-resolution models. However, despite the fact that the high-resolution models "resolve" most of these features, the improvements in temperature or salinity are inconsistent among the different model families and some regions show increased bias over their low-resolution counterparts. Greatly enhanced horizontal resolution does not deliver unambiguous bias improvement in all regions for all models.

scholarly journals The DeepWater Horizon Oil Slick: High Resolution Model Simulations of River Front Effects, Initialized and Verified by Satellite Observations

2019 ◽  
Author(s):  
Lars Robert Hole ◽  
Knut-Frode Dagestad ◽  
Johannes Röhrs ◽  
Cecilie Wettre ◽  
Vassiliki H. Kourafalou ◽  
...  
Keyword(s):  
High Resolution ◽  
Droplet Size ◽  
Wave Breaking ◽  
Deepwater Horizon ◽  
Ocean Model ◽  
Satellite Observations ◽  
Single Wave ◽  
River Input ◽  
Oil Slick ◽  
River Outflow

The effect of river fronts on oil slick transport has been demonstrated using high resolution forcing models and a fully fledged oil drift model, OpenOil. The model system is used to simulate the 2010 DeepWater Horizon oil spill. Metocean forcing data are taken from the GoM-HYCOM 1/50° ocean model with realistic river input and ECMWF global forecast products of wind and wave parameters with 1/8° resolution. The simulations are initialized from satellite observations of the surface oil patch. OpenOil includes most of the relevant processes, such as emulsification, evaporation, wave entrainment, stranding and droplet formation. The model takes account of the actual oil type and properties, using the ADIOS oil weathering database of NOAA. The effect of using a newly developed parameterization for oil droplet size distribution is studied and compared to a traditional algorithm. Although the algorithms provide different distributions for a single wave breaking event, it is found that the net difference after long simulations is negligible, indicating that the outcome is robust regarding the choice of parameterization. That indicates that the wave entrainment, vertical mixing and re-surfacing mechanisms that are part of OpenOil are more important for determining the final droplet size spectrum than the spectrum prescribed for individual wave breaking events. In both cases, the size of the droplets controls how much oil is present at the surface and hence are subject to wind and Stokes drift. The effect of removing river outflow in the ocean model is investigated in order to showcase effects of river induced fronts on oil spreading. A consistent effect on the amount and location of stranded oil is found, and considerable impact of river induced fronts is seen on the location of the surface oil patch. During a case with large river outflow (May 20-27, 2010), the total amount of stranded oil is reduced by about 50% in the simulation with no river input. The results compares well with satellite observations of the surface oil patch.

High-frequency and meso-scale winter sea-ice variability in the Southern Ocean in a high-resolution global ocean model

2018 ◽  
Vol 68 (3) ◽  
pp. 347-361 ◽  
Author(s):  
Achim Stössel ◽  
Jin-Song von Storch ◽  
Dirk Notz ◽  
Helmuth Haak ◽  
Rüdiger Gerdes
Keyword(s):  
High Resolution ◽  
Southern Ocean ◽  
Sea Ice ◽  
High Frequency ◽  
Ocean Model ◽  
Global Ocean ◽  
Meso Scale
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