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1.
We propose an improvement of the algorithm of joint assimilation of the data on climatic temperature, salinity, and altimetric
sea level in a model of circulation. Unlike the previous works, the variances of the forecast errors of temperature and salinity
and the cross-covariance functions of of the forecast errors of salinity-level and temperature-level depend on the dynamics
of waters. It is shown that the structure of the fields of cross-covariance functions in the upper mixed layer is formed by
the vertical turbulent diffusion of the variances of forecast errors of temperature and salinity. At greater depths, these
statistical characteristics are mainly determined by the vertical advection. We compared the results of calculations with
and without taking into account the dynamics of the statistical characteristics. The analysis of the influence of the dynamics
of these characteristics makes it possible to reconstruct the mutually adapted climatic fields of temperature, salinity, and
horizontal and vertical current velocities in the Black Sea with the assimilation of data in the numerical model in each time
step.
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 4, pp. 18–31, July–August, 2008. 相似文献
2.
V. V. Knysh S. G. Demyshev G. K. Korotaev A. S. Sarkisyan 《Izvestiya Atmospheric and Oceanic Physics》2007,43(3):363-377
A method for combined assimilation of climatic hydrologic fields of temperature, salinity, and the climatic dynamic level of the Black Sea into a model of sea dynamics is proposed. The monthly mean fields of the dynamic sea level were obtained from the results of assimilation of satellite altimetry data into the model. The statistical characteristics of errors in the forecasts of the level, salinity, and temperature were assumed to be proportional to the statistical characteristics of the differences between monthly mean climatic fields of temperature, salinity, and sea level calculated by means of assimilating altimetry observations of the sea level and analogous climatic hydrologic fields. The climatic fields of currents are reconstructed and analyzed. The assimilation of the climatic altimetry level allows the reproduction (in current fields) of quasi-stationary synoptic anticyclonic eddies located along the periphery of the Black Sea Rim Current. 相似文献
3.
We propose a procedure of reconstruction of the continuous (in time) climatic annual behavior of circulation in the Black Sea based on the successive assimilation of the climatic distributions of temperature and salinity in the complete nonlinear model. We use monthly average arrays interpolated for each day of a year by expanding in harmonic functions of time. Various procedures aimed at the assimilation of data are studied by taking into account the variance of measurement errors. Our main attention is given to the analysis of qualitative and quantitative characteristics of vertical motions in the sea depending on the quality of the data and parameters of the model. The main version of calculations is illustrated by the maps of annual variability of the fields of sea level, horizontal currents, and vertical velocity. 相似文献
4.
We propose an algorithm of adaptive statistics of prognostic errors aimed at the assimilation of the climatic temperature
and salinity fields in a model of dynamics of the sea. The algorithm is used for the numerical solution of the proposed differential
equations for the dispersions of prognostic errors of temperature and salinity. The sources in the equations of advective
diffusion of heat and salt depend on the four-dimensional dispersions of prognostic errors and one-dimensional (along the
vertical coordinate) dispersions of measurement errors. The dispersions of prognostic errors are corrected at the times of
assimilation of the data. We perform the reconstruction and analysis of the climatic fields of currents in the Black Sea.
It is shown that the structure of the fields of dispersions in the upper mixed layer is determined by the vertical diffusion.
Below this layer, the distribution of dispersions depends on the vertical advection. The algorithm of adaptive statistics
of prognostic errors allows us to reconstruct the improved mutually adapted hydrophysical parameters with regard for the dynamics
of the dispersions of errors.
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Translated from Morskoi Gidrofizicheskii Zhurnal, No. 1, pp. 26–37, January–February, 2008. 相似文献
5.
We realize the algorithm of adaptive statistics of forecasting errors for the assimilation of the climatic fields of temperature
and salinity in the σ-coordinate model of the dynamics of the Black Sea. The principal relations of this algorithm and its
simplified version based on the Kalman filter are presented. The distinctive features of realization of the algorithm specified
by the model are discussed. We also present the results of comparison of the hydrophysical fields of the Black Sea reconstructed
according to the algorithm of adaptive statistics and a simplified scheme of assimilation of the climatic data. It is shown
that the dependence of sources in the transport equations (heat and salt diffusion) on the four-dimensional variances of forecasting
errors and threedimensional measurement errors enables one to reconstruct the mutually adapted climatic parameters of the
sea more exactly. 相似文献
6.
Correlations between the changes in the climate of the Caspian Sea region and in its level and the variations in the North Atlantic climate are studied. The indices of North Atlantic oscillation (NAO), Atlantic multidecadal oscillation (AMO), the intensity of Atlantic thermohaline circulation (ATHC), and the air humidity above the North Atlantic are used as basic indicators of climatic variations that influence the Caspian Sea. Results of an experiment for reproducing the World Ocean circulation and the parameterization of cyclic climate peculiarities made it possible to reveal their impact on the formation of Eurasian climatic variability and on the level regime of the Caspian Sea. This impact is studied through the variability of ATHC, the NAO index, and a composite index of moisture transport (CIMT) that is proposed as a result of the studies. 相似文献
7.
We analyze the seasonal variability of the climatic hydrophysical fields of the Black Sea reporduced in three numerical experiments
carried out according to the model of circulation. The numerical predictions are performed for a period of 12.5 yr on the
basis of the hydrological data accumulated in 1983–1995. The monthly average climatic fields of the current speed are reconstructed
according to the data on the climatic fields of temperature and salinity by the method of hydrodynamic adaptation (standard).
It is shown that, in prognostic calculations, the seasonal variability of temperature and salinity is qualitatively close
to the “standard” dependence. At the same time, the quantitative difference between the climatic behavior of the model and
the standard dependence may be significant. The annual cycle of the currents is characterized by the intensification of the
Main Black-Sea Current in winter. The structure of the hydrophysical fields of the sea in the model becomes much more realistic
if it is based on the actual hydrological data.
Translated by Peter V. Malyshev and Dmitry V. Malyshev 相似文献
8.
V. V. Knysh G. K. Korotaev S. G. Demyshev V. N. Belokopytov 《Physical Oceanography》2005,15(3):142-160
We compare the thermohaline and dynamic characteristics of the Black Sea reconstructed by using two versions of climatic temperature
and salinity fields:old (1903–1982)and new (1903–2003). The fields are reconstructed with the help of continuous assimilation
of the climatic temperature and salinity in the model. It is shown that the climatic thermohaline fields constructed with
regard for the data of observations for the last 20 yr are characterized by an insignificant elevation of the halocline (pycnocline)in
the winter-spring period and the elevation of the upper boundary of the cold intermediate layer in the spring-summer period.
The intensity of surface geostrophic currents is greater than the same quantity computed on the basis of the old climatic
data for the whole year. The horizontal currents in the sea computed according to the new climatic data are more intense.
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Translated from Morskoi Gidrofizicheskii Zhurnal, No. 3, pp. 11–30, May–June, 2005. 相似文献
9.
基于ROMS模式利用集合最优插值同化沿轨海表面高度异常数据的研究 总被引：2，自引：1，他引：1
The ensemble optimal interpolation （EnOI） is applied to the regional ocean modeling system （ROMS） with the ability to assimilate the along-track sea level anomaly （TSLA）. This system is tested with an eddy-resolving system of the South China Sea （SCS）. Background errors are derived from a running seasonal ensemble to account for the seasonal variability within the SCS. A fifth-order localization function with a 250 km localization radius is chosen to reduce the negative effects of sampling errors. The data assimilation system is tested from January 2004 to December 2006. The results show that the root mean square deviation （RMSD） of the sea level anomaly decreased from 10.57 to 6.70 cm, which represents a 36.6% reduction of error. The data assimilation reduces error for temperature within the upper 800 m and for salinity within the upper 200 m, although error degrades slightly at deeper depths. Surface currents are in better agreement with trajectories of surface drifters after data assimilation. The variance of sea level improves significantly in terms of both the amplitude and position of the strong and weak variance regions after assimilating TSLA. Results with AGE error （AGE） perform better than no AGE error （NoAGE） when considering the improvements of the temperature and the salinity. Furthermore, reasons for the extremely strong variability in the northern SCS in high resolution models are investigated. The results demonstrate that the strong variability of sea level in the high resolution model is caused by an extremely strong Kuroshio intrusion. Therefore, it is demonstrated that it is necessary to assimilate the TSLA in order to better simulate the SCS with high resolution models. 相似文献
10.
S. G. Demyshev V. V. Knysh G. K. Korotaev 《Izvestiya Atmospheric and Oceanic Physics》2006,42(5):555-567
A scheme of a periodic assimilation of climatic temperature and salinity data into a model is proposed. In accordance with the criteria chosen on the basis of numerical experiments, an optimum assimilation period of three hours is set. The proposed method allows a hydrodynamic adaptation of the fields of temperature, salinity, and flow velocity that are close to the climatic ones within the framework of the proposed criteria. The main feature of the adapted fields of vertical flows in the layer 0–700 m is their smooth character and an almost complete absence of small-scale noise. The extreme values of vertical velocity in this layer decrease by almost an order of magnitude as compared to analogous values calculated for the variant of data assimilation with a weak adjustment of fields. 相似文献
11.
An eddy-resolving model of the thermohydrodynamics of the Caspian Sea is presented. The model reproduces the climatic (decadal) variability of the sea level. Numerical experiments were performed to reconstruct the sea circulation and the evolution of its level in the second half of the 20th century. We also investigate how variations in some natural and anthropogenic factors influencing the Caspian Sea water balance impact the long-term trends of its level. 相似文献
12.
G. K. Korotaev A. S. Sarkisyan V. V. Knysh P. N. Lishaev 《Izvestiya Atmospheric and Oceanic Physics》2016,52(4):418-430
A retrospective analysis has been done for the hydrophysical fields of the Black Sea for 1993–2012 with the assimilation of undisturbed monthly average profiles of temperature and salinity that were obtained by using an original procedure of joint processing of satellite altimetry and rare hydrological observations. The accuracy of the reconstructed fields of temperature and salinity of the Black Sea is evaluated by comparison with the data of sounding from the hydrological stations and the Argo floats. A comparative analysis is performed for the integral characteristics of the fields of temperature, salinity, and kinetic energy with the same characteristics of the reanalysis for 1992–2012 that assimilated the average annual profiles of temperature and salinity, surface temperature and altimetry level of the sea after being adjusted with respect to climate seasonal variability. The proposed procedure of the reanalysis execution allows a more precise reconstruction of the interannual variability of temperature and salinity stratification in the main pycnocline. The correlation between the annual and seasonal variability of the eddy of the wind friction tangential stress and the average kinetic energy at the levels is revealed. 相似文献
13.
The hydrographic fields in the Arctic region are calculated with a three-dimensional nonlinear model of the general circulation
in the World Ocean using climatic databases on temperature, salinity, and wind stress. The calculation results show that the
seasonal variability of the fields is negligible. The salinity distribution almost does not change from season to season,
and slight temperature differences are found only in the upper layer. In the winter period, a moderate intensification of
the currents is observed. The formation of an intermediate low-salinity layer is revealed at the Subantarctic front, where
the intensive turbulence and transverse circulation in the Antarctic Circumpolar Current near the front result in the sinking
of the surface low-salinity waters down to intermediate depths. The low-salinity water propagates in the oceans at intermediate
depths northward from the front by advection. The integral values of the seasonal transport of mass, heat, and salt in various
sections are presented in tables, and the distributions of appropriate characteristics in these sections are shown in figures.
According to the calculations, the highest seasonal variations of heat, salt, and mass exchange in the Antarctic region and
adjacent oceans are found in the Atlantic sector. 相似文献
14.
To study the long-term variability of the thermohaline and dynamic characteristics of the Black Sea, we use three versions
of climatic fields, namely, the fields reconstructed in the model according to the old (1903–1982) and new (1903–2003) hydrological
climatic data arrays of temperature and salinity and according to the data of satellite altimetry. The analysis of the altimetry-based
climatic fields confirms the distinctions (established earlier according to the old and new data arrays) in the seasonal variability
of the integral characteristics of temperature and salinity and in the structures of hydrophysical fields in the sea. It is
shown that, in the winter-spring season, the thermohaline fields reconstructed according to the new and altimetry data arrays
are characterized by a small elevation of the halocline (pycnocline) and the upper boundary of the cold intermediate layer.
In all seasons, the altimetry-based surface geostrophic currents contain numerous mesoscale eddies with different signs of
rotation. Moreover, in all seasons, the Rim Current reconstructed according to the altimetry data is characterized by a narrower
jet almost along the entire its length. This jet is especially intense near the coasts of West Anatolia.
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Translated from Morskoi Gidrofizicheskii Zhurnal, No. 4, pp. 3–17, July–August, 2006. 相似文献
15.
《Oceanologica Acta》1998,21(3):393-417
Available climatic and atmospheric analysis data have been used to prepare forcing functions for the Black Sea numerical model, based on the Bryan-Semtner-Cox Modular Ocean Model and including parameterizations for the atmosphere-ocean exchange, inflow through the strait of Bosphorus and the Mediterranean plume. Atmospheric data from different sources are compared and the drawbacks of some of them illustrated. A new wind stress data set, based on ship observations, is prepared. Compared to the existing wind stress estimates, the present ones use additional data and more accurate parameterization of the boundary layer physics. The intercomparison between forcing data sets is focused on the heat flux and freshwater flux at the sea surface.The model simulates adequately vertical stratification, seasonal variability and horizontal patterns. Five data sets for heat flux, freshwater flux and wind stress are used in different combinations to study the model response. The large differences between the simulations, forced by different wind stress and identical thermohaline forcing, justify the computation of the new wind stress. Though the forcing data used are perhaps close to the best available at the moment for the Black Sea, the model simulations range in large intervals and some of them are very poor. The model responses to forcing functions of different origin give rough estimates on the possible errors in present-day simulations. Some inconsistencies give clear indications that further verifications, improvements of the forcing functions, and intercomparisons between the responses simulated by the ocean circulation models are needed. 相似文献
16.
17.
G. K. Korotaev P. N. Lishaev V. V. Knysh 《Izvestiya Atmospheric and Oceanic Physics》2016,52(9):961-973
The methodology of joint processing of the satellite altimetry and occasional hydrological observations in the Black Sea for 1993–2012 is developed. The original technique for reconstruction of the 3D temperature and salinity fields in the deep-sea part is proposed and implemented. This technique makes it possible to identify the depths at which a contribution of adiabatic processes to the deformation of the temperature and salinity profiles of the sea is predominant. Daily-averaged 3D fields of the seawater temperature and salinity in a baroclinic layer on a regular grid are reconstructed. The evaluation of accuracy of the reconstructed temperature and salinity arrays is performed by comparing them with the data of hydrological exploration. Structures of the temperature and salinity fields are correlated naturally with topography of the altimetric level and clearly indicate the synoptic variability. Seasonal and interannual variabilities of the kinetic energy (averaged over horizons of the 63–400 m layer) of the geostrophic currents calculated using the dynamic method makes it possible to reveal a sharp increase in the kinetic energy of the currents in the winter season of 2002. A high correlation is found between the interannual variability of the ERA-Interim wind stress curl averaged over the surface of the deep sea part and the kinetic energy of the geostrophic currents in the 63–400 m layer. 相似文献
18.
东海冷涡对东亚季风年代际变化 总被引：1，自引：0，他引：1
利用CORA、COADS和SODA 等高分辨率的海洋和大气再分析资料及区域海洋模式(ROMS), 研究了东海冷涡对1976/1977 年前后东亚季风年代际跃变(减弱)的响应。结果表明: (1)1976/1977年前后东亚季风跃变后, 夏季东海冷涡明显增强, 主要表现为冷涡的温度显著降低, 而冬季东海冷涡有所变弱但其温度上升不明显; (2)东亚冬季风跃变后, 济州岛西南侧的黄海暖流减弱, 冷涡区出现一个反气旋式环流异常, 这有利于冬季东海冷涡的减弱; (3)东亚夏季风跃变后, 台湾暖流外海侧分支及济州岛西南侧的黄海暖流分支增强, 使得冷涡区的气旋性环流变强, 这有利于夏季东海冷涡的加强。数值试验的结果表明, 东亚冬、夏季风的跃变在东中国海引起了不同的中尺度海洋环流异常, 从而导致东海冷涡对东亚冬、夏季风的跃变产生不同的响应。 相似文献
19.
Vicente Fernndez David E. Dietrich Robert L. Haney Joaquín Tintor 《Progress in Oceanography》2005,66(2-4):321
In this paper, we present the results from a 1/8° horizontal resolution numerical simulation of the Mediterranean Sea using an ocean model (DieCAST) that is stable with low general dissipation and that uses accurate control volume fourth-order numerics with reduced numerical dispersion. The ocean model is forced using climatological monthly mean winds and relaxation towards monthly climatological surface temperature and salinity. The variability of the circulation obtained is assessed by computing the volume transport through certain sections and straits where comparison with observations is possible. The seasonal variability of certain currents is reproduced in the model simulations. More important, an interannual variability, manifested by changes in currents and water mass properties, is also found in the results. This may indicate that the oceanic internal variability (not depending on external atmospheric forcing), is an important component of the total variability of the Mediterranean circulation; variability that seems to be very significant and well documented by in situ and satellite data recovered in the Mediterranean Sea during the last decade. 相似文献
20.
Under strong surface wind forcing during winter, direct current observations in the northern Sea of Japan show the existence of strong near-inertial currents in the deep water that is characterized by the extremely homogeneous vertical structures of temperature and salinity. However, the mechanism generating internal waves in the deep water of the northern Sea of Japan has not been well understood. In this study, to clarify the dynamical link between the surface wind forcing and near-inertial currents in the deep water of the northern Sea of Japan, we drive a general circulation model taking into account realistic wind stress, ocean bottom and land topography. In the northern Sea of Japan, the numerical results show that vertically coherent horizontal currents with a speed of ~ 0.05 m s?1 are excited throughout the homogeneous deep water. A two-layer model successfully reproduces the pattern of the horizontal current velocities shown by the general circulation model, indicating that internal waves emanate westward from the northwestern coast of Japan through coastal adjustment to the strong wind forcing event and, while propagating into the ocean interior, they excite evanescent near-inertial response throughout the lower layer below the interface. 相似文献