Algorithm for HF radar vector current measurements   总被引：1，自引：0，他引：1  

Lei Liu  Xiongbin Wu  Feng Cheng  Shaolin Yang  Hengyu Ke 《Journal of Oceanography》2007,63(1):47-66

A new algorithm is proposed, called the stream function method (SFM) for producing vector current maps from radial data measured by dual-site high frequency surface wave radar (HFSWR). In SFM, a scalar stream function is constructed under some oceanographic assumptions. The function describes the two-dimensional (2-D) ocean surface water motion and is used to obtain the distribution of vector currents. The performance of SFM is evaluated using simulated radial data, which demonstrates that SFM has advantages over typical vectorial combination methods (VCM) both in error acceptance and robustness, and excels another method based on least-squares fitting (LSF) in recovering the complicated current models. Furthermore, SFM is capable of providing the total currents based on radials from single-site radar. We also test the assumptions of horizontal non-divergence in the simulation. The new algorithm is applied to the field experiment data of Wuhan University’s ocean state measuring and analyzing radar (OSMAR), collected in the coastal East China Sea during April 11–17, 2004. Quantitative comparisons are given between radar results by three current algorithms and in-situ current meter measurements. Preliminary analysis of the vertical current shear is given based on the current meter measurements.  相似文献   

Variations in the sedimentation in Kara Bogaz Gol Bay related to sea level fluctuations during the Novocaspian time     

Yu. A. Karpychev 《Oceanology》2007,47(6):857-864

The structure of the bottom sediments in Kara Bogaz Gol Bay is correlated with the history of the sea level fluctuations in the Caspian Sea during the Novocaspian time based on the radiocarbon geochronology of the coastal and bottom sediments. Instrumental observations of the sea level and the hydrochemical regime of the bay are considered to substantiate the correlations obtained.  相似文献   

Volcanogenic complexes of the Sea of Okhotsk and the Sea of Japan (Comparative analysis)     

E. P. Lelikov  T. A. Emel’yanova 《Oceanology》2007,47(2):273-281

Several coeval volcanogenic complexes indicating synchronous volcanic events in the Sea of Japan and the Sea of Okhotsk are defined. Volcanics from different-age complexes of the Sea of Okhotsk show many features in common and are attributed to the Pacific type of calc-alkaline series. They were formed in geodynamic settings of the active continental margin and point to its origination on the continental crust of the fragmented Asian continent margin. The volcanic rocks developed in the Sea of Japan reflect different rifting stages. The initial stage was marked by an eruption of calc-alkaline lavas (Paleocene-Eocene complex). At the stage of the marginal-sea spreading, erupted volcanics of the middle Miocene-Pliocene complex were melted from the depleted mantle and magmatism terminated by an eruption of postspreading Pliocene-Holocene volcanics melted from the enriched mantle EM I. Along with the differences, the magmatism in the Sea of Japan and Sea of Okhotsk has some features in common. In both cases, the sialic component of the lithosphere substantially influenced the magma generation.  相似文献   

Tectonic core of a sedimentary drift: a potential ridge propagation feature beneath the Blake Outer Ridge     

Dayton Dove  Steven C. Jaume  Erin Beutel 《Marine Geophysical Researches》2007,28(1):1-11

The Blake Outer Ridge is a 480–kilometer long linear sedimentary drift ridge striking perpendicular to the North American coastline. By modeling free-air gravity anomalies we tested for the presence of a crustal feature that may control the location and orientation of the Blake Outer Ridge. Most of our crustal density models that match observed gravity anomalies require an increase in oceanic crustal thickness of 1–3 km on the southwest side of the Blake Outer Ridge relative to the northeast side. Most of these models also require 1–4 km of crustal thinning in zone 20–30 km southwest of the crest of the Blake Outer Ridge. Although these features are consistent with the structure of oceanic fracture zones, the Blake Outer Ridge is not parallel to adjacent known fracture zones. Magnetic anomalies suggest that the ocean crust beneath this feature formed during a period of mid-ocean ridge reorganization, and that the Blake Outer Ridge may be built upon the bathymetric expression of an oblique extensional feature associated with ridge propagation. It is likely that the orientation of this trough acted as a catalyst for sediment deposition with the start of the Western Boundary Undercurrent in the mid-Oligocene.  相似文献   

Transformation of black-sea waters in the Sea of Marmara     

A. S. Zapevalov  S. V. Dovgaya 《Physical Oceanography》2007,17(2):106-112

The analysis is performed on the basis of comparison of the hydrological characteristics of prestrait regions of the Sea of Marmara. It is shown that, in summer, the Black-Sea waters are weakly mixed with the Mediterranean waters and the levels of salinity in the prestrait regions differ by 0.6–0.9‰. In winter, the indicated difference increases and the level of salinity near the entrance of Dardanelles reaches 29‰ and exceeds the level observed near the entrance of Bosporus by 5.5‰. In the analyzed regions, we observe local temperature maxima and minima near the interface of two water masses. This is explained by the presence of strong seasonal variations of temperature for the Black-Sea waters and their absence for the Mediterranean waters. The physical mechanisms responsible for the seasonal variations of the intensity of transformations of the Black-Sea waters are discussed. __________ Translated from Morskoi Gidrofizicheskii Zhurnal, No. 2, pp. 49–55, March–April, 2007.  相似文献   

Second-order moment advection scheme applied to Arctic Ocean simulation   总被引：2，自引：0，他引：2  

M.A. Morales Maqueda  G. Holloway   《Ocean Modelling》2006,14(3-4):197-221

We apply the second-order moment (SOM) advection scheme of (Prather, M.J. 1986. Numerical advection by conservation of second-order moments. J. Geophys. Res. 91, 6671–6681.) to the simulation of the large-scale circulation of the Arctic Ocean with a coupled ocean–sea-ice model. Compared to three other advection schemes commonly employed in ocean simulations (centred differences, flux corrected transport, and multidimensional positive definite advection transport), the SOM method helps preserve the vertical structure of Arctic water masses. The depth, thickness and hydrographic properties of the Arctic Surface Water and the Arctic Atlantic Layer are better represented with SOM than with any of the other three advection algorithms. We also present a convenient method for calculating the implicit numerical diffusivity of upstream based schemes, such as the SOM method, and discuss three approaches for improving the monotonicity properties of the SOM algorithm.  相似文献   

Electronic atlas of the Russian Arctic coastal zone     

D. S. Drozdov  F. M. Rivkin  V. Rachold  G. V. Ananjeva-Malkova  N. V. Ivanova  I. V. Chehina  M. M. Koreisha  Yu. V. Korostelev  E. S. Melnikov 《Geo-Marine Letters》2005,25(2-3):81-88

A set of digital maps including geology, Quaternary sediments, landscapes, engineering-geological, vegetation, geocryological and the series of regional sources have been selected to characterize the Russian Arctic coast. Based on this data, new maps of engineering geocryological zoning and zoning of the coast with respect to the intensity of exogenous geological processes and risk of technogenic impacts have been generated at the scales of 1:4,000,000–1:8,000,000. These maps are a tool to assess the impact of industry on the Arctic coast of the country.  相似文献   

Eddy Shedding from the Kuroshio Bend at Luzon Strait   总被引：16，自引：1，他引：16  

Yinglai?JiaEmail author  Qinyu?Liu 《Journal of Oceanography》2004,60(6):1063-1069

TOPEX/POSEDIENT-ERS satellite altimeter data along with the mean state from the Parallel Ocean Climate Model result have been used to investigate the variation of Kuroshio intrusion and eddy shedding at Luzon Strait during 1992–2001. The Kuroshio penetrates into the South China Sea and forms a bend. The Kuroshio bend varies with time, periodically shedding anticyclonic eddies. Criteria of eddy shedding are identified: 1) When the shedding event occurs, there are usually two centers of high Sea Surface Height (SSH) together with negative geostrophic vorticity in the Kuroshio Bend (KB) area. 2) Between the two centers of high SSH there usually exists positive geostrophic vorticity. These criteria have been used to determine the eddy shedding times and locations. The most frequent eddy shedding intervals are 70, 80 and 90 days. In both the winter and summer monsoon period, the most frequent locations are 119.5°E and 120°E, which means that the seasonal variation of eddy shedding location is unclear.  相似文献   

Dynamic-Stochastic Modeling of Natural Processes     

E. M. Igumnova  I. E. Timchenko 《Physical Oceanography》2004,14(6):348-359

We propose a method for the construction of dynamic-stochastic models of natural systems based on the assimilation of the data of observations in the prognostic equations of coupled processes. In these models, the method of adaptive balance of causes is used to deduce evolutionary equations of the analyzed processes and assimilate the data of observations in these equations. The deduced general equations are considered for an example of a marine ecosystem characterized by the development of four coupled processes. It is shown that the optimal prediction of these processes requires the solution of 11 systems of equations with simultaneous adaptation of prognostic estimates and the coefficients of the models to the data of observations. A numerical simulation experiment explaining the algorithm of the proposed method of modeling is considered. A conclusion is made that the application of this method in the geoinformation systems of monitoring of the environment is quite promising.__________Translated from Morskoi Gidrofizicheskii Zhurnal, No. 6, pp. 31–42, November–December, 2004.  相似文献   

High-resolution measurements of chromophoric dissolved organic matter in the Mississippi and Atchafalaya River plume regions   总被引：4，自引：0，他引：4  

Robert F. Chen  G. Bernard Gardner 《Marine Chemistry》2004,89(1-4):103

Chromophoric dissolved organic matter (CDOM) was measured in the spring and summer in the northern Gulf of Mexico with the ECOShuttle, a towed, instrumented, undulating vehicle. A submersible pump mounted on the vehicle supplied continuously flowing, uncontaminated seawater to online instruments in the shipboard laboratory and allowed discrete samples to be taken for further analysis. CDOM in the northern Gulf of Mexico was dominated by freshwater inputs from the Mississippi River through the Birdfoot region and to the west by discharge from the Atchafalaya River. CDOM was more extensively dispersed in the high-flow period in the spring but in both time periods was limited by stratification to the upper 12 m or so. Thin, subsurface CDOM maxima were observed below the plume during the highly stratified summer period but were absent in the spring. However, there was evidence of significant in situ biological production of CDOM in both seasons.The Mississippi River freshwater end member was similar in spring and summer, while the Atchafalaya end member was significantly higher in the spring. In both time periods, the Atchafalaya was significantly higher in CDOM and dissolved organic carbon (DOC) than the Mississippi presumably due to local production and exchange within the coastal wetlands along the lower Atchafalaya which are absent along the lower Mississippi. Nearshore waters may also have higher CDOM due to outwelling from coastal wetlands. High-resolution measurements allow the differentiation of various water masses and are indicative of rapidly varying (days to weeks) source waters. Highly dynamic but conservative mixing between various freshwater and marine end members apparently dominates CDOM distributions in the area with significant in situ biological inputs (bacterial degradation of phytoplankton detritus), evidence of flocculation, and minor photobleaching effects also observed. It is clear that high-resolution measurements and adaptive sampling strategies allow a more detailed examination of the processes that control CDOM distributions in river-dominated systems.  相似文献