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1.
Two prognostic experiments taking into account real atmospheric forcing for 2006 and 2011 were carried out based on the eddy-resolving numerical model with a horizontal resolution of 1.6 km for the Black Sea. The main dynamic features such as the Rim Current, the Sevastopol, and Batumi anticyclones are reproduced in both experiments. The model results are confirmed via observation data. We accomplished the analysis of simulated circulation and energetics. The results demonstrate that both the vertical viscosity and vertical diffusion along with the energy inflow from the wind have been the main contributors to the annual and seasonal budgets of kinetic and potential energies of the Black Sea circulation. It is shown that two regimes of the Black Sea general circulation are implemented depending on a magnitude of wind contribution to the kinetic energy in winter. Intensive mesoscale eddy formation was observed along the Anatolian, Caucasian, and Crimean coasts. The analysis of the Black Sea circulation and eddy energetics allowed us to conclude that the generation and development of the mesoscale coastal eddies is associated with the barotropic instability in case of intensive coastal currents and is associated with both the barotropic and baroclinic instability in case of weak coastal currents.  相似文献   

2.
This paper discusses the variability of surface currents around Sekisei Lagoon using a nested grid ocean circulation model. We developed a triple-nested grid system that consists of a coarse-resolution (1/60° or ∼1.85 km) model off Taiwan, an intermediate-resolution (1/300° or ∼370 m) model around the Yaeyama Islands, and a fine-resolution (1/900° or ∼123 m) model of Sekisei Lagoon. The nested grid system was forced by wind and heat flux calculated from six-hourly atmospheric reanalysis data and integrated over the period from May to July 2003. The coarse-resolution model was driven by lateral boundary conditions calculated from daily ocean reanalysis data to include realistic variation of the Kuroshio and mesoscale eddies with spatial scales of ∼500–700 km in the open ocean. The tidal forcing was included in the intermediate-resolution model by interpolating sea level data obtained from a data-assimilative tidal model. The results were then used to drive the fine-resolution model to simulate the surface water circulation around Sekisei lagoon. Model results show that (1) currents inside the lagoon are mainly driven by tide and wind; (2) there exists a strong southwestward current along the bottom slope in the southeast portion of the lagoon; the current is mainly driven by remote mesoscale eddies and at times intensified by the local wind; (3) the flow relaxation scheme is effective in reducing biases along the open boundaries. The simulated currents were used to examine the retention and dispersion of passive particles in the surface layer. Results show that the surface dispersion in the strong open ocean current region is significantly higher than that inside the lagoon.  相似文献   

3.
The Pearl River Estuary (PRE) in South China's Guangdong Province is a subtropical estuary with highly irregular topography and dynamically complicated circulations. A nested-grid coastal circulation modelling system is used in this study to examine dynamic responses of the PRE to tides, meteorological forcing and buoyancy forcing. The nested-grid modelling system is based on the Princeton Ocean Model and consists of three downscaling subcomponents: including an outer-most model with a coarse horizontal resolution of ~7 km for simulating tidally forced and wind-driven surface elevations and depth-mean currents over the China Seas from Bohai Sea to the northern South China Sea and an innermost model with a fine resolution of ~1.2 km for simulating the 3D coastal circulation and hydrography over the PRE and adjacent coastal waters. Model results during the winter northeast monsoon surge in January and super typhoon Koryn in June of 1993 are used to demonstrate that the 3D coastal circulation and hydrographic distributions in the PRE are affected by tides, winds and buoyancy forcing associated with river discharge from the Pearl River with significant seasonal and synoptic variabilities.  相似文献   

4.
In this paper, we use the unstructured grid model SCHISM to simulate the thermohydrodynamics in a chain of baroclinic, interconnected basins. The model shows a good skill in simulating the horizontal circulation and vertical profiles of temperature, salinity, and currents. The magnitude and phases of the seasonal changes of circulation are consistent with earlier observations. Among the mesoscale and subbasin-scale circulation features that are realistically simulated are the anticyclonic coastal eddies, the Sebastopol and Batumi eddies, the Marmara Sea outflow around the southern coast of the Limnos Island, and the pathway of the cold water originating from the shelf. The superiority of the simulations compared to earlier numerical studies is demonstrated with the example of model capabilities to resolve the strait dynamics, gravity currents originating from the straits, high-salinity bottom layer on the shallow shelf, as well as the multiple intrusions from the Bosporus Strait down to 700 m depth. The warm temperature intrusions from the strait produce the warm water mass in the intermediate layers of the Black Sea. One novel result is that the seasonal intensification of circulation affects the interbasin exchange, thus allowing us to formulate the concept of circulation-controlled interbasin exchange. To the best of our knowledge, the present numerical simulations, for the first time, suggest that the sea level in the interior part of the Black Sea can be lower than the sea level in the Marmara Sea and even in some parts of the Aegean Sea. The comparison with observations shows that the timings and magnitude of exchange flows are also realistically simulated, along with the blocking events. The short-term variability of the strait transports is largely controlled by the anomalies of wind. The simulations demonstrate the crucial role of the narrow and shallow strait of Bosporus in separating the two pairs of basins: Aegean-Marmara Seas from one side and Azov-Black Seas from the other side. The straits of Kerch and Dardanelles provide sufficient interbasin connectivity that prevents large phase lags of the sea levels in the neighboring basins. The two-layer flows in the three straits considered here show different dependencies upon the net transport, and the spatial variability of this dependence is also quite pronounced. We show that the blocking of the surface flow can occur at different net transports, thus casting doubt on a previous approach of using simple relationships to prescribe (steady) outflow and inflow. Specific attention is paid to the role of synoptic atmospheric forcing for the basin-wide circulation and redistribution of mass in the Black Sea. An important controlling process is the propagation of coastal waves. One major conclusion from this research is that modeling the individual basins separately could result in large inaccuracies because of the critical importance of the cascading character of these interconnected basins.  相似文献   

5.
This paper presents an assessment of the impact of the ocean circulation on modeled wave fields in the Southern Ocean, where a systematic positive bias of the modeled wave height against altimetry data has been reported. The inclusion of ocean currents in the wave model considerably reduces the positive bias of the simulated wave height for high southern latitudes. The decrease of wave energy in the presence of currents is almost exclusively related to the reduction of the relative wind, caused by an overall co-flowing current field associated with the Antarctic Circumpolar Current. Improvements of the model results are also found for the peak period and the mean period against a long-term moored buoy. At the mooring location, the effect of currents is greater for larger and longer waves, suggesting remotely generated swells are more influenced by the currents than local waves. However, an additional qualitative analysis using high-resolution currents in a finer grid nested to the global coarser grid shows that typical resolution of global hydrodynamic reanalysis is not sufficient to resolve mesoscale eddies, and as a consequence, the simulation of mesoscale wave patterns can be compromised. The results are also discussed in terms of the accuracy of forcing fields.  相似文献   

6.
A high resolution (3–8 km grid), 3D numerical ocean model of the West Caribbean Sea (WCS) is used to investigate the variability and the forcing of flows near the Meso-American Barrier Reef System (MBRS) which runs along the coasts of Mexico, Belize, Guatemala and Honduras. Mesoscale variations in velocity and temperature along the reef were found in seasonal model simulations and in observations; these variations are associated with meandering of the Caribbean current (CC) and the propagation of Caribbean eddies. Diagnostic calculations and a simple assimilation technique are combined to infer the dynamically adjusted flow associated with particular eddies. The results demonstrate that when a cyclonic eddy (negative sea surface height anomaly (SSHA)) is found near the MBRS the CC shifts offshore, the cyclonic circulation in the Gulf of Honduras (GOH) intensifies, and a strong southward flow results along the reef. However, when an anticyclonic eddy (positive SSHA) is found near the reef, the CC moves onshore and the flow is predominantly westward across the reef. The model results help to explain how drifters are able to propagate in a direction opposite to the mean circulation when eddies cause a reversal of the coastal circulation. The effect of including the Meso-American Lagoon west of the Belize Reef in the model topography was also investigated, to show the importance of having accurate coastal topography in determining the variations of transports across the MBRS. The variations found in transports across the MBRS (on seasonal and mesoscale time scales) may have important consequences for biological activities along the reef such as spawning aggregations; better understanding the nature of these variations will help ongoing efforts in coral reef conservation and maintaining the health of the ecosystem in the region.  相似文献   

7.
Arne Melsom 《Ocean Dynamics》2005,55(3-4):338-350
A set of two simulation ensembles of the ocean circulation in the North Sea, the Skagerrak and bordering seas has been run for the ten year period that started in January 1992. The ensembles differed only in the horizontal grid resolution. The main purposes of this investigation are (1) to quantify the variability that can be expected in multi-year simulations due to noise-like perturbations in the initial fields, and (2) to examine the robustness of model results for mesoscale features that form on the front between the Norwegian Coastal Current and water masses that are of an Atlantic Ocean origin. It is shown that the model resolution has a substantial impact on the ensemble variability, and that the role of small perturbations become more significant as the grid mesh is refined. Nevertheless, it is demonstrated that in a region to the west of the southern tip of Norway, eddies are occasionally found in the same positions at the same time in the results from all members of the ensembles. This is particularly the case in the aftermath of outbreak events of low salinity water masses from the Skagerrak into the North Sea.  相似文献   

8.
The main objective of the LAgrangian Transport EXperiment (LATEX) project was to study the influence of coastal mesoscale and submesoscale physical processes on circulation dynamics, cross-shelf exchanges, and biogeochemistry in the western continental shelf of the Gulf of Lion, Northwestern Mediterranean Sea. LATEX was a five-year multidisciplinary project based on the combined analysis of numerical model simulations and multi-platform field experiments. The model component included a ten-year realistic 3D numerical simulation, with a 1 km horizontal resolution over the gulf, nested in a coarser 3 km resolution model. The in situ component involved four cruises, including a large-scale multidisciplinary campaign with two research vessels in 2010. This review concentrates on the physics results of LATEX, addressing three main subjects: (1) the investigation of the mesoscale to submesoscale processes. The eddies are elliptic, baroclinic, and anticyclonic; the strong thermal and saline front is density compensated. Their generation processes are studied; (2) the development of sampling strategies for their direct observations. LATEX has implemented an adaptive strategy Lagrangian tool, with a reference software available on the web, to perform offshore campaigns in a Lagrangian framework; (3) the quantification of horizontal mixing and cross-shelf exchanges. Lateral diffusivity coefficients, calculated in various ways including a novel technique, are in the range classically encountered for their associated scales. Cross-shelf fluxes have been calculated, after retrieving the near-inertial oscillation contribution. Further perspectives are discussed, especially for the ongoing challenge of studying submesoscale features remotely and from in situ data.  相似文献   

9.
Mesoscale eddies exist almost everywhere in the ocean and play important roles in the ocean circulation of the world. These eddies may cause sound spread singular regions and bring great influences to the upwater ship and underwater aircraft. Due to the lack of hydrographic survey datasets, study of mesoscale eddies has been greatly restricted. Fortunately, satellite altimeter provided an effective way to study mesoscale eddies. An automatic detection algorithm is introduced to detect mesoscale eddies of specific intensity and spatial/temporal scale based on satellite sea surface height (SSH) data and the algorithm is applied in a strong eddy activity region: the South China Sea and the Northwest Pacific. The algorithm includes four steps. The first step is preprocessing of the SSH image, which includes elimination of error SSH data and interpolation. The second step is to detect suspected mesoscale eddies from preprocessed SSH images by dynamic threshold adjustment and morphological method, and the suspected mesoscale eddy detection includes two procedures: suspected mesoscale eddy core region detection and suspected mesoscale eddy brim extraction. The third step is to pick out mesoscale eddies satisfied with specified criteria from suspected mesoscale eddies. The criteria include three items, that is, intensity criterion, spatial scale, criterion and temporal scale criterion. The last step is algorithm performance analysis and verification. The algorithm has the capability of adaptive parameter adjustment, and can extract mesoscale eddies of interested intensity and spatial/temporal scale. The paper can provide a basis for analyzing space-time characteristics of mesoscale eddy in the South China Sea and the Northwest Pacific.  相似文献   

10.
The role of data assimilation procedures on representing ocean mesoscale variability is assessed by applying eddy statistics to a state-of-the-art global ocean reanalysis (C-GLORS), a free global ocean simulation (performed with the NEMO system) and an observation-based dataset (ARMOR3D) used as an independent benchmark. Numerical results are computed on a 1/4 ° horizontal grid (ORCA025) and share the same resolution with ARMOR3D dataset. This “eddy-permitting” resolution is sufficient to allow ocean eddies to form. Further to assessing the eddy statistics from three different datasets, a global three-dimensional eddy detection system is implemented in order to bypass the need of regional-dependent definition of thresholds, typical of commonly adopted eddy detection algorithms. It thus provides full three-dimensional eddy statistics segmenting vertical profiles from local rotational velocities. This criterion is crucial for discerning real eddies from transient surface noise that inevitably affects any two-dimensional algorithm. Data assimilation enhances and corrects mesoscale variability on a wide range of features that cannot be well reproduced otherwise. The free simulation fairly reproduces eddies emerging from western boundary currents and deep baroclinic instabilities, while underestimates shallower vortexes that populate the full basin. The ocean reanalysis recovers most of the missing turbulence, shown by satellite products , that is not generated by the model itself and consistently projects surface variability deep into the water column. The comparison with the statistically reconstructed vertical profiles from ARMOR3D show that ocean data assimilation is able to embed variability into the model dynamics, constraining eddies with in situ and altimetry observation and generating them consistently with local environment.  相似文献   

11.
Large freshwater fluxes into the Bay of Bengal by rainfall and river discharges result in strong salinity fronts in the bay. In this study, a high-resolution coupled atmosphere-ocean-wave model with comprehensive physics is used to model the weather, ocean circulation, and wave field in the Bay of Bengal. Our objective is to explore the submesoscale activity that occurs in a realistic coupled model that resolves mesoscales and allows part of the submesoscale field. Horizontal resolution in the atmosphere varies from 2 to 6 km and is 13 km for surface waves, while the ocean model is submesoscale permitting with resolutions as high as 1.5 km and a vertical resolution of 0.5 m in the upper 10 m. In this paper, three different cases of oceanic submesoscale features are discussed. In the first case, heavy rainfall and intense downdrafts produced by atmospheric convection are found to force submesoscale currents, temperature, and salinity anomalies in the oceanic mixed layer and impact the mesoscale flow. In a second case, strong solitary-like waves are generated by semidiurnal tides in the Andaman Sea and interact with mesoscale flows and fronts and affect submesoscale features generated along fronts. A third source of submesoscale variability is found further north in the Bay of Bengal where river outflows help maintain strong salinity gradients throughout the year. For that case, a comparison with satellite observations of sea surface height anomalies, sea surface temperature, and chlorophyll shows that the model captures the observed mesoscale eddy features of the flow field, but in addition, submesoscale upwelling and downwelling patterns associated with ageostrophic secondary circulations along density fronts are also captured by the model.  相似文献   

12.
Based on eddy-permitting ocean circulation model outputs, the mesoscale variability is studied in the Sea of Okhotsk. We confirmed that the simulated circulation reproduces the main features of the general circulation in the Sea of Okhotsk. In particular, it reproduced a complex structure of the East-Sakhalin current and the pronounced seasonal variability of this current. We established that the maximum of mean kinetic energy was associated with the East-Sakhalin Current. In order to uncover causes and mechanisms of the mesoscale variability, we studied the budget of eddy kinetic energy (EKE) in the Sea of Okhotsk. Spatial distribution of the EKE showed that intensive mesoscale variability occurs along the western boundary of the Sea of Okhotsk, where the East-Sakhalin Current extends. We revealed a pronounced seasonal variability of EKE with its maximum intensity in winter and its minimum intensity in summer. Analysis of EKE sources and rates of energy conversion revealed a leading role of time-varying (turbulent) wind stress in the generation of mesoscale variability along the western boundary of the Sea of Okhotsk in winter and spring. We established that a contribution of baroclinic instability predominates over that of barotropic instability in the generation of mesoscale variability along the western boundary of the Sea of Okhotsk. To demonstrate the mechanism of baroclinic instability, the simulated circulation was considered along the western boundary of the Sea of Okhotsk from January to April 2005. In April, the mesoscale anticyclonic eddies are observed along the western boundary of the Sea of Okhotsk. The role of the sea ice cover in the intensification of the mesoscale variability in the Sea of Okhotsk was discussed.  相似文献   

13.
This study examines the circulation and associated monthly-to-seasonal variability in the Caribbean Sea using a regional ocean circulation model. The model domain covers the region between 99.0 and 54.0°W and between 8.0 and 30.3°N, with a horizontal resolution of 1/6°. The ocean circulation model is driven by 6-hourly atmospheric reanalysis data from the National Center for Environmental Prediction and boundary forcing extracted from 5-day global ocean reanalysis data produced by Smith et al. (Mercator Newsletter 36:39–49, 2010), and integrated for 7 years. A comparison of model results with observations demonstrates that the regional ocean circulation model has skill in simulating circulation and associated variability in the study region. Analysis of the model results, as well as a companion model run that uses steady annual mean forcing, illustrates the role of Caribbean eddies for driving monthly-to-seasonal circulation variability in the model. It is found that vertically integrated transport between Nicaragua and Jamaica is influenced by the interaction between the density perturbations associated with Caribbean eddies and the Nicaraguan Ridge. The impact of Caribbean eddies squeezing through the Yucatan Channel is also discussed.  相似文献   

14.
Qilin Wan  Jianjun Xu 《水文研究》2011,25(8):1327-1341
The evolution and structure of rainstorms associated with a flash‐flood event are simulated by the Advanced Weather Research and Forecasting (WRF‐ARW) model of the National Center for Atmospheric Research and the Gridpoint Statistical Interpolation (GSI) data assimilation (DA) system of the National Oceanic and Atmospheric Administration (NOAA) of the United States. The event is based on a flash flood that occurred in the central Guangdong Province of south‐east China during 20–21 June 2005. Compared to an hourly mixed rain‐gauge and satellite‐retrieved precipitation data, the model shows the capability to reproduce the intensity and location of rainfall; however, the simulation depends on three conditions to a large extent: model resolution, physical processes schemes and initial condition. In this case, the Eta Ferrier microphysics scheme and the initialization with satellite radiance DA with a fine 4‐km grid spacing nested grid and coarse 12‐km grid spacing outer grid are the best options. The model‐predicted rain rates, however, are slightly overestimated, and the activities of the storms do not precisely correspond with those observed, although peak values are obtained. Abundant moisture brought by the south‐westerly winds with a mesoscale low‐level jet from the South China Sea or Bay of Bengal and trapped within the XingfengJiang region encompassed by northern Jiulian, southern Lianhua and eastern small mountains are apparently the primary elements responsible for the flood event. All simulated rainstorms were initiated over the southern slopes of the Jiulian Mountain and moved south or north‐eastward within the Xingfengjiang region. Meanwhile, the Skew‐T/Log‐P diagrams show that there is a fairly high convective available potential energy (CAPE) over the active areas of the rainstorms. The higher CAPE provides a beneficial thermodynamic condition for the development of rainstorms, but the higher convective inhibition near the northern, eastern and southern mountains prohibits the storms from moving out of the region and causes heavy rainfall that is trapped within the area. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

15.
A chain of three nested models, based on the MARS 3D code, is used to simulate the North-western Mediterranean Sea circulation with a finest grid of 1.2 km resolution and 30 vertical sigma levels. This modelling system allows to resolve the coastal dynamics taking into account the influence of the general basin circulation. The aim of this study is to assess the ability of the nested MARS-3D models to reproduce most of the circulation features observed in the North-western Mediterranean Basin and in the Gulf of Lions. Comparisons of modelled sea surface temperature and salinity with MEDAR/MEDATLAS climatology and NOAA/AVHRR satellite measurements show that the model accurately reproduces the large and coastal scale variability. Over the Northern Basin, the seasonal changes of the cyclonic gyre extension are correctly simulated, even though in summer, the modelled temperature of the surface layer remains in basin-average 1°C cooler than the satellite measured temperature. As soon as the stratification erodes, modelled and observed temperatures become closer. Over the Gulf of Lions, realistic coastal responses are obtained under different wind conditions. Upwellings are correctly located and their intensity and spatial extension were here improved by the use of Aladin wind fields (10 km spatial resolution) and the introduction of a drag coefficient fitted according to the stability of the planetary boundary layer. The dispersion of fresh Rhone water discharge and the mesoscale circulation simulated by MARS-3D also agree with satellite measurements.  相似文献   

16.
Trajectories and hydrological data from two Argo floats indicate that warm and salty water at 200–300-m depths was ejected from the coast of Oman, near Ras al Hamra, in spring 2008, 2011, and 2012. This warm and salty water, Persian Gulf Water (PGW), once ejected from the coast, recirculated cyclonically in the western Sea of Oman, but also flowed eastward along the Iranian and Pakistani coasts. There, it was expelled seaward by mesoscale eddies as shown by other float data. Seasonal maps of salinity were computed from all available Argo floats; they showed that, in spring, PGW is present in the middle and north of the Sea of Oman, contrary to fall, when the salinity maxima lie southeast of Ras al Hadd. The ejection of PGW from Ras al Hamra is related here to the influence of a mesoscale dipolar eddy which often appears near this cape in spring. The time-averaged and empirical orthogonal functions of altimetric maps over 11 years for this season confirm the frequent presence and the persistence of this feature. From surface currents and hydrology, deep currents were computed via thermal wind balance, and the associated shear and strain fields were obtained. This deformation field is intense near Ras al Hamra, with an offshore direction. This flow structure associated with the mesoscale dipole explains PGW ejection from the coast. This observation suggests that PGW distribution in the Northern Arabian Sea can be strongly influenced by seasonal mesoscale eddies.  相似文献   

17.
The main oceanographic objective of the future SWOT mission is to better characterize the ocean mesoscale and sub-mesoscale circulation, by observing a finer range of ocean topography dynamics down to 20 km wavelength. Despite the very high spatial resolution of the future satellite, it will not capture the time evolution of the shorter mesoscale signals, such as the formation and evolution of small eddies. SWOT will have an exact repeat cycle of 21 days, with near repeats around 5–10 days, depending on the latitude. Here, we investigate a technique to reconstruct the missing 2D SSH signal in the time between two satellite revisits. We use the dynamical interpolation (DI) technique developed by Ubelmann et al. (2015). Based on potential vorticity (hereafter PV) conservation using a one and a half layer quasi-geostrophic model, it features an active advection of the SSH field. This model has been tested in energetic open ocean regions such as the Gulf Stream and the Californian Current, and has given promising results. Here, we test this model in the Western Mediterranean Sea, a lower energy region with complex small scale physics, and compare the SSH reconstruction with the high-resolution Symphonie model. We investigate an extension of the simple dynamical model including a separated mean circulation. We find that the DI gives a 16–18% improvement in the reconstruction of the surface height and eddy kinetic energy fields, compared with a simple linear interpolation, and a 37% improvement in the Northern Current subregion. Reconstruction errors are higher during winter and autumn but statistically, the improvement from the DI is also better for these seasons.  相似文献   

18.
The circulation in the Straits of Florida is dominated by the throughflow of the Florida Current, as modified by tidal flows, responses to atmospheric cold front and extratropical cyclone (easterly wave and tropical cyclone) passages in winter (summer), and intrinsic mesoscale variability due to instabilities of the Florida Current front and jet system. Monthly meanders of the Florida Current, persistent oceanic fronts associated with the Florida Current’s baroclinic jet, and frontal eddies shed weekly by the Florida Current are the primary mesoscale features. A limited area model (Princeton Ocean Model: POM) is implemented to cover the Straits of Florida with a curvilinear grid that resolves the mesoscale structure, especially where the baroclinic flow is locked to steep topography in a 90 degree bend of the Straits. Florida Current cyclonic frontal eddies are spawned spontaneously, grow as they translate downstream, interact with shelf waters, and exhibit the same space-time attributes that characterize their observed counterparts, as evidenced by satellite imagery, shipboard synoptic mapping, coastal HF radar, and moored time series. Here, a deeper understanding is attempted for the frontal eddy kinematics and dynamics by examining, for example, their sensitivity to model parameter values, synoptic versus monthly atmospheric forcing, and other determinants of the flow. The mean flow shears are concentrated along the shelfbreak, where these frontal eddies are trapped, favoring the formation of the eddies by mean flow instabilities. In particular, it is found that the Florida Current frontal eddies exist independent of the wind-forcing considered (i.e., no winds, monthly winds, and synoptic (but not mesoscale) winds); however, they are modulated by the synoptic wind-forcing. Nevertheless, intriguingly, the frontal eddies have the same weekly time scale as the weather cycle.  相似文献   

19.
First results are presented from a 3-D, time dependent, high resolution, nested grid model that has been developed to study mesoscale processes in the global, coupled thermosphere–ionosphere system. This new Thermosphere–Ionosphere Nested Grid (TING) model, which is an extension of the National Center for Atmospheric Researchs thermosphere–ionosphere general circulation model (NCAR–TIGCM), runs on a UNIX workstation. The TING model simultaneously calculates global (coarse resolution) and local (high resolution) distributions of neutral and plasma winds, temperature and composition. It is comprised of two coupled codes—a global TIGCM and an adjustable nested grid code which uses the same solvers as the TIGCM, but has higher spatial and temporal resolution. The size, location and level of nesting of the high resolution grid(s) are adjustable to suit the specific application. The coupling between the coarse (TIGCM) grid and the nested interior grids is via a one-way interaction scheme. In this scheme, the TIGCM output influences the nested grid model by providing initial conditions and temporally evolving boundary conditions, but the outputs from the nested grid are not permitted to influence the TIGCM. Diurnally-reproducible results of the TING model are presented for solar-maximum, winter solstice, geomagnetically-quiet conditions. The TING model successfully simulates well-known thermosphere–ionosphere features that are smeared or not modeled at the spatial resolutions used in standard TIGCMs. These include the sub-auroral electron density trough, the polar cap hole and the polar cap tongue of ionization.  相似文献   

20.
The surface ocean circulation in the Caribbean Sea is characterized by the interaction between anticyclonic eddies and the Caribbean Upwelling System (CUS). These interactions lead to instabilities that modulate the transfer of kinetic energy up- or down-cascade. The interaction of North Brazil Current rings with the islands leads to the formation of submesoscale vorticity filaments leeward of the Lesser Antilles, thus transferring kinetic energy from large to small scales. Within the Caribbean, the upper ocean dynamic ranges from large-scale currents to coastal upwelling filaments and allow the vertical exchange of physical properties and supply KE to larger scales. In this study, we use a regional model with different spatial resolutions (6, 3, and 1 km), focusing on the Guajira Peninsula and the Lesser Antilles in the Caribbean Sea, in order to evaluate the impact of submesoscale processes on the regional KE energy cascade. Ageostrophic velocities emerge as the Rossby number becomes O(1). As model resolution is increased submesoscale motions are more energetic, as seen by the flatter KE spectra when compared to the lower resolution run. KE injection at the large scales is greater in the Guajira region than in the others regions, being more effectively transferred to smaller scales, thus showing that submesoscale dynamics is key in modulating eddy kinetic energy and the energy cascade within the Caribbean Sea.  相似文献   

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