Dynamical Ocean Model Research Articles

Climates of Warm Earth-like Planets. II. Rotational “Goldilocks” Zones for Fractional Habitability and Silicate Weathering

Abstract Planetary rotation rate has a significant effect on atmospheric circulation, where the strength of the Coriolis effect in part determines the efficiency of latitudinal heat transport, altering cloud distributions, surface temperatures, and precipitation patterns. In this study, we use the ROCKE-3D dynamic ocean general circulation model to study the effects of slow rotations and increased insolations on the “fractional habitability” and silicate weathering rate of an Earth-like world. Defining the fractional habitability f h to be the percentage of a planet’s surface that falls in the 0 ≤ T ≤ 100 °C temperature regime, we find a moderate increase in f h with a 10% and 20% increase in insolation and a possible maximum in f h at sidereal day lengths between 8 and 32 times that of the modern Earth. By tracking precipitation and runoff, we further determine that there is a rotational regime centered on a 4 day period in which the silicate weathering rate is maximized and is particularly strongly peaked at higher overall insolations. Because of weathering’s integral role in the long-term carbonate–silicate cycle, we suggest that climate stability may be strongly affected by the anticipated rotational evolution of temperate terrestrial-type worlds and should be considered a major factor in their study. In light of our results, we argue that planetary rotation period is an important factor to consider when determining the habitability of terrestrial worlds.

Study of sensitivity of the algorithm for assimilating small amount of data in the ocean dynamics model

Study of sensitivity of the algorithm for assimilating small amount of data in the ocean dynamics model

Issledovanie chuvstvitel'nosti algoritma usvoeniya malochislennykh dannykh nablyudeniy v modeli dinamiki okeana

Issledovanie chuvstvitel'nosti algoritma usvoeniya malochislennykh dannykh nablyudeniy v modeli dinamiki okeana

The Impact of the Processes in the Southern Ocean on ENSO Development

The paper presents the review of the model study of the role of the Southern Ocean in the processes of interaction of the ocean-atmosphere system at short time scales impacting the El Niño–Southern Oscillation (ENSO). It is shown that the variability of wind and atmospheric pressure over the Antarctic Circumpolar Current (ACC), together with the effects of the topography and coastline, significantly impact the development of ENSO events. A new paradigm for ENSO is proposed that allows explaining the current weakening of the interrelation between the variability in wind and water volume in the tropical warm pool in the western equatorial Pacific and the onset of ENSO. The weakness of the interrelationship between ENSO and variability in the equatorial warm water volume of the equatorial Pacific, together with wind variability in the western equatorial Pacific, can be explained by the fact that the process occurred in the Southern Ocean recently became a major contributor amplifying ENSO events. The reproduction in numerical models of ocean dynamics for the mechanism found can improve the accuracy of the forecast of El Niño events.

Biogeography of zooplankton feeding strategy

AbstractThe trait‐based approach is increasingly used in plankton ecology to understand diversity, community dynamics, and biogeography. While on the global scale phytoplankton traits are fairly well established, zooplankton traits are only beginning to be understood. One taxa‐transcending aspect of zooplankton diversity is the distinction between ambush and active feeding strategies. We present a global‐scale empirical estimate of feeding strategy derived from copepod abundance observations, which for the first time suggests a distinct trait biogeography with ambush feeding as the dominant feeding strategy at higher, but not at lower latitudes. To explain this trait biogeography, we develop a minimalist trade‐off based model of feeding strategies based on encounter rates between zooplankton predators and their phyto‐ and zooplankton prey. Encounter rates are governed by the two traits, size and motility, that trade off against predation risk. Coupled to a three‐dimensional dynamic green ocean model, our idealized encounter model captures the observed feeding strategy biogeography. In the model, this pattern arises from competing dominant food chains within the food web and is shaped by a trophic trait cascade of active vs. passive feeding in adjacent trophic levels. The dominant feeding strategy structures the pathways and efficiency of energy and biomass transfer through the model food web, with consequences for primary production, export and higher trophic levels. Understanding feeding strategies is therefore important for fisheries, biogeochemical cycling, and long‐term predictions of ecosystem dynamics and functioning by global dynamic green ocean models.

Determination of the mean dynamic ocean topography model through combining multi-source gravity data and DTU15 MSS around China's coast

Mean dynamic ocean topography (or MDT) is closely related to ocean circulation and global climate change. It has important scientific significance and application value for the development and utilization of marine resources in China's coastal areas. Based on the terrain gravity, marine gravity, and SRTM 3 s data, an algorithm to reduce the problem of gravity data gaps between land and sea is proposed. A consistent land-sea gravity model is established based on point-mass fusion method. Then geoid model, which accuracy was estimated to be 8.5 cm through the verification of 348 GNSS/level data from the coastal provinces, of China's coastal areas was calculated through remove-restore technique. Connecting the above geoid model with DTU15 MSS model to establish a MDT model in China's coastal areas using the direct method in space domain. The effect of gravity field model, dominant factors of sea surface topography, and low pass filter are analyzed. Taking Bohai Sea and Yellow Sea as an example, and comparing MDT with the two international models CNES_2013_MDT and DTU15_MDT. The results show that the MDT has the potential to construct a vertical datum of the ocean and carry out related scientific research and application.

Some Results of Studies in the Area of Numerical Weather Prediction and Climate Theory in Siberia

The results of studies in the area ofnumerical weather prediction and climate theory are presented. These results were obtained by the team of researchers of the Siberian school of mathematical modeling of atmosphere and ocean dynamics established by academician G.I. Marchuk. Academician V.P. Dymnikov played an enormous role in the development of this school by enriching it with new approaches and ideas. His contribution to the Siberian school of mathematical modeling was most strongly pronounced concerning three problems: numerical weather prediction for the Siberian region, the modeling of the climate system dynamics, and the mathematics and theory of climate.

On a Three-Dimensional Nonlinear Model of Pacific Equatorial Ocean Dynamics: Velocities and Flow Paths

On a Three-Dimensional Nonlinear Model of Pacific Equatorial Ocean Dynamics: Velocities and Flow Paths

Integrated ocean acoustics and dynamics modeling with computer clusters

Underwater sound propagation in the ocean can be influenced by a variety of physical oceanographic processes, including ocean currents, eddies, internal gravity waves, tides, fronts, instabilities, etc. Our group at the Woods Hole Oceanographic Institution has been developing several numerical simulation frameworks to integrate ocean acoustic and dynamical models and implement them on computer clusters. Most of the current dynamical ocean models run on clusters, and we will review our integration approaches in this talk and also point out the requirement for nesting model domains and interpolations. Different parallelization schemes will be introduced to speed up a variety of acoustic numerical models, for example, ray-tracing, normal modes, couple modes and Parabolic-Equation approximation models. Examples of 3D sound propagation in a number of ocean environments (canyons, slopes, continental shelves and basins) with different dominating ocean processes will be demonstrated. Model performance improvement and limitation will be discussed. [Work sponsored by the ONR.]

Моделирование динамики океана с усвоением данных наблюдений

Моделирование динамики океана с усвоением данных наблюдений

Assimilation of the AVISO Altimetry Data into the Ocean Dynamics Model with a High Spatial Resolution Using Ensemble Optimal Interpolation (EnOI)

A parallel realization of the Ensemble Optimal Interpolation (EnOI) data assimilation (DA) method in conjunction with the eddy-resolving global circulation model is implemented. The results of DA experiments in the North Atlantic with the assimilation of the Archiving, Validation and Interpretation of Satellite Oceanographic (AVISO) data from the Jason-1 satellite are analyzed. The results of simulation are compared with the independent temperature and salinity data from the ARGO drifters.

Estimation of the Tropical Pacific Ocean State 2010–13

AbstractA data-assimilating ⅓° regional dynamical ocean model is evaluated on its ability to synthesize components of the Tropical Pacific Ocean Observing System. The four-dimensional variational data assimilation (4DVAR) method adjusts initial conditions and atmospheric forcing for overlapping 4-month model runs, or hindcasts, that are then combined to give an ocean state estimate for the period 2010–13. Consistency within uncertainty with satellite SSH and Argo profiles is achieved. Comparison to independent observations from Tropical Atmosphere Ocean (TAO) moorings shows that for time scales shorter than 100 days, the state estimate improves estimates of TAO temperature relative to an optimally interpolated Argo product. The improvement is greater at time scales shorter than 20 days, although unpredicted variability in the TAO temperatures implies that TAO observations provide significant information in that band. Larger discrepancies between the state estimate and independent observations from Spray gliders deployed near the Galápagos, Palau, and Solomon Islands are attributed to insufficient model resolution to capture the dynamics in strong current regions and near coasts. The sea surface height forecast skill of the model is assessed. Model forecasts using climatological forcing and boundary conditions are more skillful than climatology out to 50 days compared to persistence, which is a more skillful forecast than climatology out to approximately 20 days. Hindcasts using reanalysis products for atmospheric forcing and open boundary conditions are more skillful than climatology for approximately 120 days or longer, with the exact time scale depending on the accuracy of the state estimate used for initializing and on the reanalysis forcing. Estimating the model representational error is a goal of these experiments.

The role of grazer predation strategies in the dynamics of consumer-resource based ecological models

We analyse a simple plankton system to provide a heuristic for more complex models such as Dynamic Green Ocean Models (DGOMs). Zooplankton foraging is either by generalist grazers that consume whatever they bump into or specialist grazers that actively seek particular prey. The zooplankton may further be classified as either facultative grazers that can survive on any of their prey or obligate grazers that depend on the presence of specific prey.A key result is that different prey dependencies can result in dramatically different impacts of grazing strategies on system outcomes. The grazing strategy can determine whether a system with obligate grazers will be stable, have regular, predictable cycles or be chaotic. Conversely, whether facultative zooplankton functioned as specialist or generalist grazers makes no qualitative difference to the dynamics of the system. These results demonstrate that the effect of different grazing strategies can be critically dependent on the grazer's dependency on specific prey. Great care must be taken when choosing functional forms for population interactions in DGOMs, particularly in scenarios such as climate change where parameters such as mortality and growth coefficients may change. A robust theoretical framework supporting model development and analysis is key to understanding how such choices can affect model properties and hence predictions.

A preliminary numerical model of three-dimensional underwater sound propagation in the Block Island Wind Farm area

The Block Island Wind Farm, consisting of five 6-MW turbines, is the first U.S. commercial offshore wind farm harvesting wind energy to generate electricity, located 3.8 miles southeast of Block Island, Rhode Island. In-situ underwater and airborne noise measurements were made during the construction and the first two months of the operational period for the purpose of environmental impact assessment. To better interpret the noise measurements and extend the noise propagation prediction beyond the coverage of listening stations, a three-dimensional underwater sound propagation model is created with a high resolution bathymetric map and a data-assimilated ocean dynamic model. The bathymetric map is made using the 3 arc-second U.S. Coastal Relief Model (CRM) with a 100-m horizontal resolution provided by the National Centers for Environmental Information (NCEI). The ocean model is extracted from the Regional Ocean Modeling System (ROMS) ESPreSSO (Experimental System for Predicting Shelf and Slope Optics) model covering the Mid-Atlantic Bight with a 5 km horizontal resolution and 36 terrain-following vertical levels. Temporal and spatial variability of noise propagation conditions is identified in the integrated acoustic and oceanographic model. Future model development incorporating surface wind waves and sub-bottom sediment layer structure will be discussed. [Work supported by BOEM.]The Block Island Wind Farm, consisting of five 6-MW turbines, is the first U.S. commercial offshore wind farm harvesting wind energy to generate electricity, located 3.8 miles southeast of Block Island, Rhode Island. In-situ underwater and airborne noise measurements were made during the construction and the first two months of the operational period for the purpose of environmental impact assessment. To better interpret the noise measurements and extend the noise propagation prediction beyond the coverage of listening stations, a three-dimensional underwater sound propagation model is created with a high resolution bathymetric map and a data-assimilated ocean dynamic model. The bathymetric map is made using the 3 arc-second U.S. Coastal Relief Model (CRM) with a 100-m horizontal resolution provided by the National Centers for Environmental Information (NCEI). The ocean model is extracted from the Regional Ocean Modeling System (ROMS) ESPreSSO (Experimental System for Predicting Shelf and Slope Optics) mo...

ARGO data assimilation into the ocean dynamics model with high spatial resolution using Ensemble Optimal Interpolation (EnOI)

The article proposes parallel implementation of the Ensemble Optimal Interpolation (EnOI) data assimilation (DA) method in eddy-resolving World Ocean circulation model. The results of DA experiments in North Atlantic with ARGO drifters are compared with the multivariate optimal interpolation (MVOI) DA scheme. The sensitivity of the model error, i.e., the difference between the model and observations depending on the number of ensemble elements, is also assessed and presented. The effectiveness of this method over the MVOI scheme is confirmed. The model outputs with and without assimilation are also compared with independent sea surface temperature data from ARMOR 3d.

Numerical model of nonhydrostatic ocean dynamics based on methods of artificial compressibility and multicomponent splitting

An algorithm is proposed for solving three-dimensional ocean hydrodynamics equations without hydrostatic approximation and traditional simplification of Coriolis acceleration. It is based on multicomponent splitting of the modified model with artificial compressibility. The original system of equations is split into two subsystems describing the transport of three velocity components and adjustment of the density and velocity fields. At the adjustment stage, the horizontal velocity components are represented as a sum of the depth means and deviations; the two corresponding subsystems are derived. For barotropic dynamics, the compressibility effect is represented as the boundary condition at the free surface, while for the baroclinic subsystem, it is introduced as e-regularization of the continuity equation. Then, the baroclinic equations are split into two subsystems describing the hydrostatic and nonhydrostatic dynamics. The nonhydrostatic dynamics is computed at a separate splitting stage. The algorithm is included into the Institute of Numerical Mathematics of the Russian Academy of Sciences model based on “primitive” equations and verified by solving the hydrodynamics problem for the Sea of Marmara.

Simulation of Arctic and North Atlantic ocean water and ice seasonal characteristics by the INMIO-CICE coupled model

The first results of simulation of the seasonal variability of the Arctic and North Atlantic ocean waters and ice by a coupled model based on a full three-dimensional ocean dynamics model INMIO4.1 and a sea-ice model CICE5.1 are considered. The coupled model can be run on massively parallel computers under control of the Compact Modelling Framework CMF2.0. The numerical experiment is performed according to the CORE-II protocol with 1948 atmospheric forcing data. Possible causes of the deviation of the model solution from the ERA-20C reanalysis and WOA09 climatology are discussed.

The study of single station inverting the sea surface current by HF ground wave radar based on adjoint assimilation technology

This paper introduces the assimilation technology in an ocean dynamics model and discusses the feasibility of inverting the sea surface current in the detection zone by assimilating the sea current radial velocity detected by single station HF ground wave radar in ocean dynamics model. Based on the adjoint assimilation and POM model, the paper successfully inverts the sea surface current through single station HF ground wave radar in the Zhoushan sea area. The single station HF radar inversion results are also compared with the bistatic HF radar composite results and the fixed point measured results by Annderaa current meter. The error analysis shows that acquisition of flow velocity and flow direction data from the single station HF radar based on adjoint assimilation and POM model is viable and the data obtained have a high correlation and consistency with the flow field observed by HF radar.

Modeling of ocean dynamics with large variations in sea level

The formulation and the algorithm of solving an ocean model for the prediction and assimilation of the observed data which makes it possible to reconstruct the circulation in the deep-water parts of the sea and at a shallow water shelf, as well as to describe the large time–space variability in the surface level, are considered. The model uses a vertical hybrid σ–z coordinate system: the several upper tens of meters of the ocean are described in the σ-coordinate system and the rest of the water column is described in the z coordinates. Such hybridization extends the possibilities of models for reconstructing thermo-hydrodynamic processes in different sea basins and the World Ocean. The differential formulation of the model in the σ–z coordinate system is presented; the simplified records of several operators that are allowable in the case of a small thickness of the ocean σ-layer are described. The construction of a computational grid, approximation of the bottom topography on it, and discretization of equations and boundary conditions of the models are considered; an approach to describing the bottom friction at shallow waters is offered. The results of the comparative experiments in the z and σ–z coordinate models are analyzed.

Seasonal forecasting for decision support in marine fisheries and aquaculture

AbstractThe production of marine protein from fishing and aquaculture is influenced by environmental conditions. Ocean temperature, for example, can change the growth rate of cultured animals, or the distribution of wild stocks. In turn these impacts may require changes in fishing or farming practices. In addition to short‐term environmental fluctuations, long‐term climate‐related trends are also resulting in new conditions, necessitating adjustment in fishing, farming and management approaches. Longer‐term climate forecasts, however, are seen as less relevant by many in the seafood sector owing to more immediate concerns. Seasonal forecasts provide insight into upcoming environmental conditions, and thus allow improved decision making. Forecasts based on dynamic ocean models are now possible and offer improved performance relative to statistical forecasts, particularly given baseline shifts in the environment as a result of climate change. Seasonal forecasting is being used in marine farming and fishing operations in Australia, including wild tuna and farmed salmon and prawns, to reduce uncertainty and manage business risks. Forecast variables include water temperature, rainfall and air temperature, and are considered useful up to approximately 4 months into the future, depending on the region and season of interest. Species‐specific habitat forecasts can also be made by combining these environment forecasts with biological habitat preference data. Seasonal forecasts are useful when a range of options are available for implementation in response to the forecasts. The use of seasonal forecasts in supporting effective marine management may also represent a useful stepping stone to improved decision making and industry resilience at longer timescales.