共查询到20条相似文献，搜索用时 93 毫秒
1.
For the Black-Sea region, we perform the dynamic reanalysis of the data on atmospheric circulation for the period 1958–2001
by using the HadRM3P model with a space resolution of 25 km. We estimate the mean climatic atmospheric fields of vorticity and divergence of the
wind velocity and study their space structure and seasonal variability. The climatic estimates of the annual course of vorticity
of the wind velocity over the sea are presented. The obtained large annual average values of vorticity of the velocity reveal
the predominant role played by the wind action in the generation not only of the seasonal variability but also of the mean
cyclonic circulation of waters in the Black Sea. 相似文献
2.
G. A. Platov 《Izvestiya Atmospheric and Oceanic Physics》2011,47(3):377-392
In this study the specific features of deepwater generation in an area of wind polynia and the capability of numerical models to transport bottom-density anomalies from shelf to deepwater areas are considered. The results of regional modeling indicate that the displacement method presented in the first part of this study leads to a considerable supply of dense deep waters at the expense of waters generated in shelf areas of the Barents and Kara seas. With the help of the given parametrization, these waters are shown to be able to numerically transport at significant distances from where they are generated to a shelf edge and deepwater oceanic areas with slightly changed initial density characteristics. This technique was tested within a large-scale combined ocean-ice model for the Arctic Ocean and the North Atlantic. With the displacement method, the numerical model was shown to have a less clearly expressed trend of decreasing the total amount of deep waters. However, this method does not eliminate the problem of adequately reproducing bottom waters in a large-scale numerical model. Based on a trend analysis of the numerical results, we found that a longer period of atmospheric influence with a prevalent cyclonic circulation leads to a decreased amount of deep waters in the Arctic Ocean, while a prevalent anticyclonic-type circulation leads to its recovery. 相似文献
3.
The seasonal and interannual variability of the heat and dynamic characteristics of the ocean is analysed based on the results of four-dimensional analysis of measurements taken in the Newfoundland energy area during 1982–1986. The horizontal and vertical large-scale circulation of waters is considered in the interaction with the quasi-steady anticyclonic eddy. Data are supplied on the response of the results of four-dimensional analysis to the initial conditions and the bulk measurement data.Translated by Mikhail M. Trufanov. 相似文献
4.
The formation of the fields of surface winds over the Black Sea occurs under the action of numerous physical factors. One
of the most important factors is the monsoon mechanism connected with the seasonal variations of buoyancy contrasts over the
sea and surrounding land. To separate the effects caused by this mechanism, we performed and described the numerical experiments
aimed at the evaluation of the sensitivity of the regional model of atmospheric circulation to the variations of land–sea
temperature contrasts. It is shown that the influence of these effects is restricted to the lower part of the atmosphere.
The presented estimates of the climatic fields of disturbances enable us to describe the monsoon mechanism specifying the
seasonal variability of the field of vorticity of the wind velocities and, as a consequence, the seasonal variability of the
large-scale circulation of waters in the Black Sea. 相似文献
5.
Progress of North Pacific mode water research in the past decade 总被引：1，自引：0，他引：1
6.
V. V. Knysh R. A. Ibrayev G. K. Korotaev N. V. Inyushina 《Izvestiya Atmospheric and Oceanic Physics》2008,44(2):236-249
We present the results of an analysis of the seasonal variability of current fields in the Caspian Sea, reconstructed by assimilation of climatic temperature and salinity into the primitive-equation model of water circulation on the basis of an algorithm for adaptive statistics of prediction errors. The sources in heat and salt transfer-diffusion equations depend on the spatial and temporal variability of the variances of prediction errors and one-dimensional (in the vertical coordinate) variances of measurement errors for temperature and salinity. The variances of prediction errors are adjusted at the moments of data assimilation in accordance with a simplified Kalman filter. The climatic circulation of waters in the Caspian Sea is shown to be highly varying. The maximum of its intensity over the entire depth is reached in February. The minimum of kinetic energy is observed in April. The currents in deep-sea areas are determined by the balance between wind and baroclinic factors of the formation of circulation with wind currents prevalent. 相似文献
7.
The seasonal cycle of circulation and transport in the Antarctic Peninsula shelf region is investigated using a high-resolution (∼2 km) regional model based on the Regional Oceanic Modeling System (ROMS). The model also includes a naturally occurring tracer with a strong source over the shelf (radium isotope 228Ra, t1/2=5.8 years) to investigate the sediment Fe input and its transport. The model is spun-up for three years using climatological boundary and surface forcing and then run for the 2004–2006 period using realistic forcing. Model results suggest a persistent and coherent circulation system throughout the year consisting of several major components that converge water masses from various sources toward Elephant Island. These currents are largely in geostrophic balance, driven by surface winds, topographic steering, and large-scale forcing. Strong off-shelf transport of the Fe-rich shelf waters takes place over the northeastern shelf/slope of Elephant Island, driven by a combination of topographic steering, extension of shelf currents, and strong horizontal mixing between the ACC and shelf waters. These results are generally consistent with recent and historical observational studies. Both the shelf circulation and off-shelf transport show a significant seasonality, mainly due to the seasonal changes of surface winds and large-scale circulation. Modeled and observed distributions of 228Ra suggest that a majority of Fe-rich upper layer waters exported off-shelf around Elephant Island are carried by the shelfbreak current and the Bransfield Strait Current from the shallow sills between Gerlache Strait and Livingston Island, and northern shelf of the South Shetland Islands, where strong winter mixing supplies much of the sediment derived nutrients (including Fe) input to the surface layer. 相似文献
8.
使用Ｓ．Ｌｅｖｉｔｕｓ的温度、盐度的气候资料，用诊断分析方法获得南海年平均和各季的海面起伏以及大尺度地转环流的统计结果，并比较了其季节变化。结果表明：南海冬、夏季的地转环流场有相反的流动趋势；但在东北部常年存在气旋式环流，在其驱动下巴士海峡西侧存在准定常的Ｎ向流；南海还存在明显的随季节变化的强流区。 相似文献
9.
利用复EOF分析,将热带太平洋5月份的大气风场和海洋上层流场看作1个整体,对其作了动力统计诊断,用以揭示热带太平洋5月份大气、海洋环流异常与长江流域梅雨丰欠的关系并考察其年际和年代际变化.诊断结果表明:在同一EOF模态中,大气部分和海洋部分的结构有很大不同,海洋模态表现出较强的赤道陷波特征;在南、北纬5°之外,海洋流场已大幅衰减掉了,而大气风场该现象不明显.EOF第1模态模的时间系数振幅从1994年起增大趋势明显,这表明气候变化剧烈程度在加大;前2个EOF模态的时间系数均具有明显的年际和年代际变化.EOF第1模态为长江流域梅雨丰欠异常模态,大气存在经圈环流异常.EOF第2模态为ENSO模态,大气存在纬圈环流异常.黑潮因处5°N以北,已离开赤道,故其流速虽大,但流场偏差则很小,即其流速异常不明显. 相似文献
10.
11.
The waters in the shallow part of the Yellow Sea and East China Sea are affected greatly by climatic and geographical conditions and fail to possess homogeneity and conservativeness like oceanic waters. They have apparent difference in modified degrees, so we may regard a certain range of mixed water as a relatively independent one. In fact, the study of water masses in the shallow sea means a modified analysis of waters. The idea of modified water masses is introduced, i. e., a water body which holds the similar physical and chemical characters, occupies a certain space, and varies seasonally and regularly. On the T-S diagram, it displays as a certain amount of points aggregated together, the centre of which changes regularly and may have a process of combination and separation.According to the clustering method, there are eight modified water masses in this area. They may also be divided into three salinity types. On the T-S diagram, the points concerning temperature and salinity of different modified 相似文献
12.
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
13.
Yu. V. Artamonov M. V. Babii A. E. Bukatov E. A. Skripaleva 《Physical Oceanography》2008,18(4):194-203
By using the data array of satellite measurements of the sea-surface temperature (SST), it is shown that the distributions
of linear trends of the SST for 17 years (1986–2002) are closely correlated with the specific features of large-scale circulation
of waters. The extreme values of trends of the SST are observed in the zones of the Gulf Stream, East-Greenland, Labrador,
and North-Atlantic Currents, North Equatorial Countercurrent, South Equatorial and Antarctic Circumpolar Currents. The differences
between the distributions of trends of the SST for some months of the year are revealed. In the zones of currents transporting
warm surface waters from the tropical areas, positive trends of the SST are observed for the most part of the year. On the
contrary, negative trends are predominant in the zones of currents transporting cold upwelling waters.
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 4, pp. 32–42, July–August, 2008. 相似文献
14.
15.
A. A. Sizov 《Physical Oceanography》1992,3(5):349-355
A conclusion about two extreme regimes existing in the large-scale circulation in the North Atlantic has been drawn based on an analysis of the inter-annual variability of the analogue to the Rossby index, as well as that of the heat and dynamic characteristics in separate areas of the north subtropical circulation. The former is defined by a high level of circulation both in the atmosphere and in the subtropical water circulation. In the current century this regime was realized mainly in the years pertaining to the middle and end of a 22-year solar activity cycle (a 22-year cycle). The relatively low level of atmospheric circulation and the slackened water mass transport are typical of the second regime. It dominated mainly during the years relevant to the beginning and second half of a 22-year solar activity cycle.Translated by Mikhail M. Trufanov. 相似文献
16.
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
17.
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
18.
Physical regularities of water exchange between the North Atlantic (NA) and Arctic Ocean (AO) in 1958–2009 are analyzed on the basis of numerical experiments with an eddy-permitting model of ocean circulation. Variations in the heat and salt fluxes in the Greenland Sea near the Fram Strait caused by atmospheric forcing generate baroclinic modes of ocean currents in the 0–300 m layer, which stabilize the response of the ocean to atmospheric forcing. This facilitates the conservation of water exchange between the NA and AO at a specific climatic level. A quick response of dense water outflow into the deep layers of the NA through the Denmark Strait to the variations in the North Atlantic Oscillation (NAO) index was revealed on the monthly scale. A response on a time scale of 39 months was also revealed. The quick response on the NAO index variation was interrupted in 1969–1978, which was related to the Great Salinity Anomaly. It was shown that transverse oscillations of the Norwegian Atlantic Current significantly influence the formation of intermediate dense waters in the Greenland and Norwegian seas (GNS). The dense water outflow by bottom current (BC) to the deep layers of the NA through the Faroe Channels with a time lag of 1 year correlates with the transversal oscillations of the Norwegian Current front. The mass transport of the BC outflow from the Faroe Channels to the NA can serve as an integral indicator of the formation and sink of new portions of dense waters formed as a result of mixing of warm saline Atlantic waters and cold freshened Arctic waters in the GNS. 相似文献
19.
The data of satellite altimetry are used to simulate the Black-Sea circulation. The altimetry data of the TOPEX/Poseidon and ERS satellites are prepared within the framework of the NASA Ocean Altimeter Pathfinder project. The additional data processing is performed to compute the dynamic level reflecting the circulation of the Black Sea. The altimetry sea-level is assimilated in an eddy-resolving model of circulation of the Black Sea based on primitive equations. The accuracy of the obtained fields of temperature and salinity is estimated by comparing with the data of large-scale hydrographic surveys according to the ComSBlack program. The prognostic capabilities of the proposed model are estimated by comparing the obtained results with the fields computed with the help of assimilation of the altimetry data. 相似文献
20.
New Development of Eastern Mediterranean Circulation based on Hydrological Observations and Current Measurements 总被引：2，自引：0，他引：2
Abstract. A number of recent studies based on hydrographic observations and modelling simulations have dealt with the major climatic shift that occurred in the deep circulation of the Eastern Mediterranean. This work presents hydrographic observations and current measurements conducted from 1997 to 1999, which reveal strong modifications in the dynamics of the upper, intermediate and deep layers, as well as an evolution of the thermohaline characteristics of the deep Aegean outflow since 1995. The reversal of the circulation in the upper layer of the north/central Ionian is worthy of note. The observations indicate a reduction of Atlantic Water in the northern Ionian with an increase on the eastern side of the basin. In the intermediate layer, the dispersal path of the Levantine Intermediate Water (LIW) is altered. Highly saline (>39.0) and well-oxygenated intermediate waters were found near the Western Cretan Arc Straits. They flow out from the Aegean, thus interrupting the traditional path of the LIW, and spread prevalently northwards into the Adriatic Sea. In the deep layer, dense waters, exiting from the Adriatic (σø −29.18 kg · m−3 ), flow against the western continental margin in the Ionian Sea at a depth of between 1000–1500 m. Dense waters of Aegean origin (> 29.20 kg · m−3 ), discharged into the central region of the Eastern Mediterranean during the early stages of the transient, propagate prevalently to the east in the Levantine basin and to the west in the northern Ionian Sea. Near-bottom current measurements conducted in the Ionian Sea reveal unforeseen aspects of deep dynamics, suggesting a new configuration of the internal thermohaline conveyor belt of the Eastern Mediterranean. 相似文献