Deviation Of Sea Level Research Articles

Analisis Parameter Fisika-Kimia untuk Kepentingan Rehabilitasi Ekosistem Mangrove di Pesisir Pulau Bungkutoko Kota Kendari

In Southeast Sulawesi rehabilitation of mangrove areas that have been damaged but in reality not all mangrove rehabilitation activities were successful, this was allegedly caused by a mismatch in the type of mangrove and incompatibility of rehabilitation techniques used with environmental conditions or parameters of the local coastal environment. This study is aimed to analyze the condition of coastal environmental parameters in Bungkutoko island, district of Abeli in rehabilitation proposed of mangrove ecosystem and to find a proper rehabilitation strategy for it can be applied in that area. This study was carried on June to July 2009 in the coastal of Bungkutoko island, Abeli district, Kendari Town. Data in this study is analyzed as descriptively for giving common view of that area. The measurement results of several physical-chemical parameters on the coast of Bungkutoko island at stations I, II and III are suitable for mangrove ecosystem rehabilitation activities, which have a slope of the base: flat and sloping, particle size: small substrate, binding capacity of substrate particles: moderate to loose, confinement coastline: protected and semi protected and open, wave: relatively small, sea level deviation: moderate, tidal type: mixture tends to double daily, current speed: weak, sediment suspension: normal and salinity: 25-35 ppt. Also pay attention to the right planting time on the condition of mangrove tree is in having fruits and calm water condition of sea. And for planting technic is propaguls directly planted to the ground and using seeds on the polybags.

Projected sea level rise, gyre circulation and water mass formation in the western North Pacific: CMIP5 inter-model analysis

Future changes in the dynamic sea level (DSL), which is defined as sea-level deviation from the global mean sea level, is investigated over the North Pacific, by analyzing data from the Coupled Model Intercomparison Project Phase 5. The analysis provides more comprehensive descriptions of DSL responses to the global warming in this region than available from previous studies, by using surface and subsurface data until the year 2300 under middle and high greenhouse-gas emission scenarios. The DSL changes in the North Pacific are characterized by a DSL rise in the western North Pacific around the Kuroshio Extension (KE), as also reported by previous studies. Subsurface density analysis indicates that DSL rise around the KE is associated with decrease in density of subtropical mode water (STMW) and with northward KE migration, the former (latter) of which is relatively strong between 2000 and 2100 for both RCP4.5 and RCP8.5 (between 2100 and 2300 for RCP8.5). The STMW density decrease is related to large heat uptake to the south and southeast of Japan, while the northward KE migration is associated with the poleward shift of the wind stress field. These features are commonly found in multi-model ensemble means and the relations among representative quantities produced by different climate models.

Altimetric data assimilation by EnOI and 3DVAR in a tropical pacific model: Impact on the simulation of variability

When altimetric data is assimilated, 3DVAR and Ensemble Optimal Interpolation (EnOI) have different ways of projecting the surface information downward. In 3DVAR, it is achieved by minimizing a cost function relating the temperature, salinity, and sea level. In EnOI, however, the surface information is propagated to other variables via a stationary ensemble. In this study, the differences between the two methods were compared and their impacts on the simulated variability were evaluated in a tropical Pacific model. Sea level anomalies (SLA) from the TOPEX/Poseidon were assimilated using both methods on data from 1997 to 2001 in a coarse resolution model. Results show that the standard deviation of sea level was improved by both methods, but the EnOI was more effective in the central/eastern Pacific. Meanwhile, the SLA evolution was better reproduced with EnOI than with 3DVAR. Correlations of temperature with the reanalysis data increased with EnOI by 0.1–0.2 above 200 m. In the eastern Pacific below 200 m, the correlations also increased by 0.2. However, the correlations decreased with 3DVAR in many areas. Correlations with the independent TAO profiles were also compared at two locations. While the correlations increased by up to 0.2 at some depths with EnOI, 3DVAR generally reduced the correlations by 0.1–0.3. Though both methods were able to reduce the model-data difference in climatological sense, 3DVAR appears to have degraded the simulated variability, especially during El Nino-Southern Oscillation events. For salinity, similar results were found from the correlations. This tendency should be considered in future SLA assimilations, though the comparisons may vary among different model implementations.

Sea-State-Dependent Momentum Fluxes for Ocean Modeling

Abstract The impact of wave-dependent surface stress on the ocean circulation has been studied using surface stresses calculated from a numerical wave model. The main questions to be investigated were what the effect would be on the Ekman currents in the upper ocean and what the impact would be on storm surge predictions. To answer the first question, the response of wave-dependent forcing on an Ekman type of model was studied. Here, the wave forcing was provided by a one-gridpoint version of the wave model. Second, the impact of the waves was studied with a three-dimensional ocean circulation model for the North Sea. Three different experiments were performed for a period of 1 yr. To test the effect on the storm surge signal, the results have been compared with sea level observations from 22 stations along the Norwegian and Dutch coasts. One of the main findings is that calculating stresses in the wave model, thereby introducing sea-state-dependent momentum fluxes, has a strong positive impact on the storm surge modeling compared with applying a traditional parameterization of surface stresses from the 10-m wind speed. When all cases with sea level deviation from the mean of less than 0.5 m were removed, the root-mean-square error for 1 yr averaged over all stations was reduced by approximately 6 cm. Splitting the momentum budget into an Eulerian and a wave part (Stokes drift) has only a negligible effect on the modeling of the sea surface elevation but increases the angular turning of the Eulerian surface drift to the right of the wind direction with an angle of about 4°.

Annual and interannual variations of the Leeuwin Current at 32°S

In this study, the annual and interannual variations of the Leeuwin Current at 32°S off the Western Australian coast are investigated. The mean annual cycle and the El Niño and La Niña composites of the Leeuwin Current temperature structures are obtained by linearly fitting a Taylor expansion to historical upper ocean temperature data. A temperature‐salinity relationship is used to derive the salinity field and geostrophy is assumed to calculate the current velocity. The downward tilting of the isotherms toward the coast and the strength of a near‐surface core of the low‐salinity water indicate the seasonal variation of the Leeuwin Current. Seasonally, the Leeuwin Current has the maximum poleward geostrophic transport of 5 Sv (106 m3 s−1) during June–July. Interannually, the Leeuwin Current is distinctly stronger during a La Niña year and weaker during an El Niño year. The annual average poleward geostrophic transports in the mean, the El Niño and La Niña years are 3.4, 3.0, and 4.2 Sv respectively. Variations of the Leeuwin Current structure on annual and interannual timescales are coastally trapped. A linear relationship between the coastal sea level deviation at Fremantle and the Leeuwin Current transport is derived, which justifies and calibrates the usage of the Fremantle sea level as an index for the strength of the Leeuwin Current.

System of tidal electric power plants supporting a prescribed power-generation curve

1. To derive the rated capacity with respect to a given load curve, it is proposed to use a system of two (or more) tidal electric power plants utilizing orthogonal hydroelectric turbines in units with a different layout, floating units, the capacity of which is proportional to the flow velocity, and stationary units, the capacity of which is proportional to the head on the unit, the latter varying approximately as the modulus of deviation of sea level from the mean. 2. It is recommended not to maximize use of local reserves of tidal energy. It is expedient to find the economical and ecological optimum of utilization of this energy, which frequently may be found to be significantly lower than the maximum possible tapping of energy. 3. The units of a hydroelectric plant with orthogonal turbines may be extremely effective not only in tidal electric plants, but also in utilizing the energy of large rivers under conditions when the construction of dams and the creation of reservoirs are complicated for economic and ecological reasons.

Observation of equatorial Kelvin solitary waves in a slowly varying thermocline

Abstract. TOPEX/POSEIDON (T/P) sea level deviation (SLD) time series from 3 October 1992 to 15 May 1997 combined with upper ocean thermal structures are used to observe the characteristics and analyze the dynamics of equatorial waves in the Pacific Ocean. The evolution of the Kelvin wave propagating along an eastward shoaling thermocline in the equatorial Pacific is investigated. The behaviour of this wave as it propagates eastward can be approximately described with the solutions of the perturbed Korteweg-de Vries (PKDV) equation and modified Green's Law. Assuming that the nonlinear term and dispersive term of this equation are balanced, the amplitude increases as the thermocline decreases to the power -3/8. Approaching the eastern Pacific, the nonlinearity increases and the relation changes to the power -9/8. The dispersion relation, and mass and energy conservations are investigated. The results indicate that under a varying thermocline, the nonlinear Kelvin solitary waves indeed exist in the real ocean.

Complex Singular Value Decomposition Analysis of Equatorial Waves in the Pacific Observed by TOPEX/Poseidon Altimeter

The mean of the sea level deviation data derived from the TOPEX/Poseidon altimeter in the equatorial Pacific, between 10°S and 10°N, and between 120°E and 78°W, from cycles 2 to 136 (3 October 1992–2 June 1996), are extracted using a maximum–minimum average method. Then, two-dimensional (2D) sea level deviation time series are developed to visualize the dynamics of equatorial waves. The complex singular value decomposition (CSVD) method is applied to decompose these 2D time series into empirical orthogonal modes. Using this method, zonal and meridional structures, propagation directions, periods, and propagation speeds of these empirical modes are obtained. The first empirical mode is propagating westward, and its structure is asymmetric to the equator. It has an average phase speed c = −0.6 m s−1 within 4°–6°N and c = −0.4 m s−1 within 6°–8°S, respectively, and a period of 15 months, which is associated with an interannual Rossby wave. The second empirical mode is propagating eastward along the equator and has a phase speed of 2.5 m s−1 and a period of 7 months, which is associated with an equatorial Kelvin wave. The asymmetric feature of the empirical Rossby wave, which is also observed in the equatorial Pacific, may suggest that the background currents and wind fields in the equatorial Pacific Ocean affect its propagation. The amplitude of the empirical Kelvin mode increases as it propagates eastward. This is associated with an eastward shoaling of the thermocline depth along the equatorial Pacific Ocean. The results of both empirical modes are consistent with those predicted by the theory of Kelvin and Rossby waves and closely represent the actual features of both waves observed in the equatorial Pacific Ocean. Therefore, the CSVD is a suitable method for revealing the dynamics of equatorial waves.