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1.
By using the archival hydrological data for 1955–1998, we analyze the trends of deep-water thermohaline characteristics of
the Black Sea and their interannual and decadal variability. It was discovered that the level of salinity increased at depths
greater than 1000 m in the west part of the sea from the mid-1950-s till the early 1980s and the opposite trend was observed
for the next 15–20 yr. The average rate of increase in the deep-water salinity between 1960 and 1980 and its decrease after
1980 was equal to 0.05‰ per 20 yr. These facts demonstrate that the water exchange through Bosporus was intensified for the
first 25 yr of the analyzed period and weakened for the next 20 yr. The interannual variability with a typical period of 6.5
yr and a quasi-20-yr periodicity are detected against the background of the parabolic trend.
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Translated from Morskoi Gidrofizicheskii Zhurnal, No. 4, pp. 18–30, July–August, 2006. 相似文献
2.
We analyze the space-and-time variability of the meridional heat transport in the North Atlantic. The contribution of various
mechanisms to the integral meridional heat transport (MHT) is estimated. The key role played by the drift transport of the
Tropical Atlantic in the formation of the meridional oceanic heat transport is confirmed. On the basis of the general analysis
of estimations obtained by various authors according to the data accumulated for 1870–2008 and the results of numerical analyses
based on the data of NCEP/NCAR reanalysis, we show that the long-term average meridional drift heat (mass) transport attains its maximum values equal to (1.6 ± 0.1)
PW [(17.4 ± 1.5) Sv] in the vicinity of 12.5°N in the Tropical Atlantic. The contribution of the heat transport caused by
the horizontal Sverdrup circulation to the integral meridional heat transport is maximum in the vicinity of 30° N. On the
average, it is equal to ∼ 40%. In the Subtropical Atlantic, the meridional heat transport varies with a period of ∼ 50–70 yr.
The minimum value of the integral meridional heat transport was attained in the mid-1960s and its maximum value was at attained
at the beginning of the 1990s. The location of the center of Azores pressure maximum makes it possible to conclude that the
intensification of the total meridional heat transport in the Subtropical Atlantic on these time scales is accompanied by
the displacement of the center of the North Subtropical anticyclonic gyre in the southwest direction. 相似文献
3.
The long-wave outgoing radiation, effective cloudiness equal to the product of the total cloud amount by their optical density,
and the sea-surface temperature determined from the satellites are used to determine the annual course of the components of
external heat balance on the sea surface whose climatic anomalies, parallel with the meridional heat and water transfer in
the ocean-atmosphere system, specify the intraannual and interannual large-scale variations of weather in different regions
of the Earth. The development of these studies is connected with the progress of satellite hydrophysics because the data obtained
from the space become sufficiently exact, regular, and global. The increase in the existing data array on the external heat
balance of the oceans from ∼15–20 to 100 yr and more would promote the solution of the problem of oscillations of Earth's
climate. We present examples of coordinated numerical analysis of the heat balance of the upper (0–100 m ) layer of the Black
Sea performed on the basis of the shipborne and satellite data.
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Translated from Morskoi Gidrofizicheskii Zhurnal, No. 6, pp. 59–75, November–December, 2007. 相似文献
4.
The data of meteorological and oceanographic observations on the northwest shelf of the Black Sea for 1973–2000 are used to
compute the characteristics of the entire area in the presence of hypoxia of waters under the pycnocline in the summer–autumn
period and the area of surface waters with a level of salinity lower than 17.5‰ in May. The time of onset of the spring warming
of air (stable transition through a temperature of 5°) is determined. A statistically significant positive trend of the air
temperature (0.8° per 100 yr) is revealed in Odessa. The process of warming was observed mainly for the winter (1.5° per 100
yr) and spring (0.8° per 100 yr) periods and became especially intense since the beginning of the 1990s. On the basis of the
data of correlation analyses, we establish a statistically significant relationship between the large-scale atmospheric processes
[the index of North Atlantic Oscillation (NAO) and the wind conditions], the area of surface waters whose salinity is lower
than 17.5‰, and the total area with hypoxia in the summer–autumn periods. For positive mean values of the NAO index (in January–March),
we most often observe early spring with elevated repetition of the south and west winds with subsequent development of hypoxia
in large areas of the northwest shelf. We propose an empirical regression model for the prediction of the total area of summer–autumn
hypoxia of waters with predictors: the onset of the spring warming of air and the area of propagation of waters whose salinity
is lower than 17.5‰ in May. The maximum error of prediction of the area with hypoxia does not exceed 5.5 ⋅ 103 km2, i.e., less than 2% of the total area of the northwest shelf in the Black Sea (to the north of 45°N). 相似文献
5.
Atlantic multidecadal oscillation and its manifestations in the Atlantic-European region 总被引：2，自引：0，他引：2
A. B. Polonskii 《Physical Oceanography》2008,18(4):227-236
We present a brief survey of the works devoted to the investigation of the Atlantic Multidecadal Oscillation, i.e., of the
quasiperiodic variations of sea-surface temperature in the North Atlantic with typical time scales of 50–100 yr. This oscillation
is a manifestation of the natural variability in the ocean-atmosphere system. The characteristic scale of the Atlantic Multidecadal
Oscillation is determined by the speed of the meridional oceanic circulation in the North Atlantic. The analyzed oscillation
affects various climatic characteristics: air temperature, river discharge in the European and North-American regions, the
number and intensity of tropical cyclones in the Atlantic Ocean, and the parameters of mid-latitude cyclones and anticyclones
in the Atlantic-European region. The main mechanism by which the Atlantic Multidecadal Oscillation affects the climatic characteristics
of the regions neighboring with the North Atlantic is the atmospheric response to the thermal anomalies in the ocean leading
to a shift of the centers of atmospheric action and to the changes in the intensity and predominant directions of propagation
of atmospheric cyclones and anticyclones. By using the results of long-term instrumental observations carried out in Eastern
Europe and the data array of reconstructed temperature in the Alpine region, it is shown that the Atlantic Multidecadal Oscillation
is responsible for a significant part of low-frequency variations of temperature in Europe. This fact confirms the potential
predictability of the regional atmospheric manifestations of the Atlantic Multidecadal Oscillation on the decadal-scale.
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 4, pp. 69–79, July–August, 2008. 相似文献
6.
The first empirical orthogonal functions (EOF1s) of surface-air temperature fluctuations for Russia and its neighboring states
within the period 1950–2005 are analyzed. The spatial distribution of the EOF1, the first principal components (PC1s) of the
observed air temperature (averaged over the summer, July, December–March, and individual winter months), and their time variations
(including trend parameters, some spectral characteristics, and the quantitative indices of relation to circulation indices
(on the basis of multiple step-by-step regression)) are considered. Significant seasonal differences have been revealed: the
winter air-temperature fluctuations are characterized by a higher (when compared to summer) spatial coherence, especially
in the latitudinal direction. The EOF1 of the winter air temperature (averaged over December–March) describes its fluctuations
for almost all of Russia; in this case, no less than 70% of the PC1 variability is due to variations in several circulation
indices; the main contribution (60%) is made by both the North Atlantic Oscillation (NAO) and Scandinavian (SCAND) indices.
On the whole, over the periods 1951–2005 and 1971–2005, the NAO contribution exceeds the SCAND contribution to the winter
temperature variability; the NAO is associated with a more rapid increase in air temperature in 1968–1997 and with the 1971–2005
trend. In 1951–1970 the main contribution to air temperature fluctuations was made by SCAND; the SCAND contribution exceeds
the NAO contribution in the periods 1951–2005 and 1971–2005. The 1971–2005 and 1968–1997 temperature trends are completely
described by variations in the NAO (70%) and SCAND (30%) indices for January and February. 相似文献
7.
By using archival monthly data for 100 yr, we analyze the statistical structure of time series characterizing the variability of the Azores High and Iceland Low. We show that there exists a long-term tendency towards approach of the centers of action of the atmosphere (CAA) in the North Atlantic and their strengthening. At the same time, quasiperiodic decadal intensification of the CAA is accompanied by an increase in the distance between them. In the spectra of sea-level pressure in the Azores High and Iceland Low, significant peaks for periods of 2–5 and 10 yr are strongly pronounced. Furthermore, oscillations with a period 50 yr are clearly seen. The main contribution to the interannual changes in the index of the North-Atlantic Oscillation (NAO) is made by pressure variability in the Iceland Low. Different ways of behavior are characteristic of the CAA for time scales of 2–7, 7–15, and more than 15 yr. Each of these variability intervals is analyzed separately. We established a significant correlation between the index of the Southern Oscillation (SO) and characteristics of the CAA of the North Atlantic only for time scales of 7–15 yr. It demonstrates that, as the SO index increases in autumn, the pressure at the center of the Azores High grows and the latitudinal distance between the Azores High and Iceland Low decreases, i.e., the zonal circulation in the North Atlantic becomes more intense. We also discuss possible mechanisms of the obtained statistical relations. 相似文献
8.
This study describes the three-dimensional distributions of the Turner angle (Tu) and the potential vorticity (PV) of the
main pycnocline water in the subtropical North Pacific (10–50°N, 120°E–120°W) using a large in situ CTD data set taken by
the Argo profiling floats during June to October of 2001–2009 to clarify the detailed distribution of the central water and
the mode waters as well as the relationship between these water masses. The ventilated part of the main pycnocline water (σ
θ < 26.7 kg m−3) in the subtropical gyre generally displays a sharp peak in Tu value of 59° in the histogram. The Tu histograms for 10° × 10°
geographical boxes mostly show that the mode for the Tu value is 59° too, but they also show some regional differences, suggesting
some types of relations with the North Pacific mode waters. To further investigate this relationship, the appearance probability
density function of the central water (defined as the main pycnocline water with Tu = 56°–63°) and those of the mode waters
with PVs lower than the critical value on each isopycnal surface were analyzed. The distribution area of the central mode
water (CMW) corresponds so well with that of the central water that a direct contribution of the CMW to the formation and
maintenance of the central water is suggested. On the other hand, the distribution areas of subtropical mode water (STMW),
Eastern STMW, and transition region mode water do not correspond to that of the central water. Nevertheless, indirect contributions
of these mode waters to the formation and maintenance of the central water through salt finger type convection or diapycnal
mixing are suggested. 相似文献
9.
Hajime Kawakami Makio C. Honda Masahide Wakita Shuichi Watanabe 《Journal of Oceanography》2007,63(6):967-982
Time-series measurements of dissolved inorganic carbon (DIC) and nutrient concentrations were conducted in the northwestern
North Pacific from October 2002 to August 2004. Assuming that data obtained in different years represented time-series seasonal
data for a single year, vertical distributions of DIC and nutrients showed large seasonal variabilities in the surface layer
(∼100 m). Seasonal variabilities in normalized DIC (nDIC) and nitrate concentrations at the sea surface were estimated to
be 81–113 μmol kg−1 and 12.7–15.7 μmol kg−1, respectively, in the Western Subarctic Gyre. The variability in nutrients between May and July was generally at least double
that in other seasons. In the Western Subarctic Gyre, estimations based on statistical analyses revealed that seasonal new
production was 39–61 gC m−2 and tended to be higher in the southwestern regions or coastal regions. The seasonal new productions in the northwestern
North Pacific were two or more times higher than in the North Pacific subtropical gyre and the northeastern North Pacific.
It is likely that this difference is due to spatial variations in the concentrations of trace metals and the species of phytoplankton
present. In addition, from estimations of surface pCO2 it was verified that the Western Subarctic Gyre is a source of atmospheric CO2 between February and May and a sink for CO2 between July and October. 相似文献
10.
Impact of the winter cooling on the variability of the thermohaline characteristics of the active layer in the Black Sea 总被引：1，自引：0，他引：1
The influence of the winter atmospheric forcing on the interannual variability of the Black Sea’s active layer’s thermohaline
structure during 1982–2008 is investigated. The results are based on the combined analysis of the hydrological measurements
from a ship, satellite measurements of the sea’s surface temperature (SST), and the NCEP/NCAR reanalysis data for the surface
air temperature (SAT). A high correlation between the variability of the winter mean SST/SAT and the thermohaline characteristics
of the active layer during the following warm season was found. It is shown that the winter atmospheric forcing significantly
affects the variability of the temperature, salinity, and density down to the 150–200 m depth, and this has to be considered
in the analysis of the interannual and long-term variability of the Black Sea’s active layer. 相似文献
11.
The seasonal climatic circulation of the sea reconstructed on the basis of assimilation of new arrays of many-year average
hydrological data in a model is analyzed. Five layers are discovered in the structure of climatic currents in the sea in depth:
the surface Ekman layer (∼ 10 m), a layer with small vertical gradients of the kinetic energy (∼ 10–60 m), a layer with relatively
high vertical gradients of the kinetic energy (∼ 60–150 m), a layer with gradual decrease in the kinetic energy and intensification
(from 250–350 m) of the east cyclonic gyre and Batumi anticyclonic eddy (∼ 150–1000 m), and an abyssal layer characterized
by an almost barotropic velocity (∼ 1000–2000 m). The specific features of the seasonal evolution of currents at these depths
are investigated. It is shown that the key role in the formation of deep-water circulation of the sea is played by the south
east flow, east cyclonic gyre, and Batumi anticyclonic eddy.
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Translated from Morskoi Gidrofizicheskii Zhurnal, No. 6, pp. 28–45, November–December, 2005. 相似文献
12.
Interannual-to-decadal variations in the subtropical countercurrent (STCC) and low potential vorticity (PV) water and their
relations in the North Pacific Ocean are investigated on the basis of a 60-year-long hindcast integration of an eddy-resolving
ocean general circulation model. Although vertically coherent variations are dominant for STCC interannual variability, a
correlation analysis shows that an intensified STCC vertical shear accompanies lower PV than usual to the north on 25.5- to
26.1-σθ isopycnal surfaces, and intensified meridional density gradient in subsurface layers, consistent with Kubokawa’s theory (J
Phys Oceanogr 29:1314–1333, 1999). The low-PV signals appear at least 2 years before peaks of STCC, propagating southwestward from the subduction region. 相似文献
13.
Eitarou Oka 《Journal of Oceanography》2009,65(2):151-164
Temperature and salinity data from 2003 through 2006 from Argo profiling floats have been analyzed to examine the formation
and circulation of the North Pacific Subtropical Mode Water (STMW) and the interannual variation of its properties over the
entire distribution region. STMW is formed in late winter in the zonally-elongated recirculation gyre south of the Kuroshio
and its extension, which extends north of ∼28°N, from 135°E to near the date line. The recirculation gyre consists of several
anticyclonic circulations, in each of which thick STMW with a characteristic temperature is formed. After spring, the thick
STMW tends to be continually trapped in the respective circulations, remaining in the formation region. From this stagnant
pool of thick STMW, some portion seeps little by little into the southern region, where southwestward subsurface currents
advect relatively thin STMW as far as 20°N to the south and just east of Taiwan to the west. The STMW formed in the recirculation
gyre becomes colder, less saline, and denser to the east, with an abrupt change of properties across 140°E and a gradual change
east of 140°E. The STMW formed east of 140°E exhibits coherent interannual variations, increasing its temperature by ∼1°C
from 2003 through 2006 and also increasing its salinity by ∼0.05 from 2003 through 2005. These property changes are clearly
detected in the southern region as far downstream as just east of Taiwan, with reasonable time lags. 相似文献
14.
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
15.
Horizontal and meridional volume transports on timescales from intra-seasonal to interannual in the North Pacific subarctic
region were investigated using a reanalysis dataset for 1993–2001 that was constructed from an assimilation of the TOPEX altimeter
and in situ data into an eddy-permitting North Pacific ocean general circulation model. The barotropic flow is excited along east of
the Emperor Seamounts by the western intensification dynamics. The volume transport of this flow compensates for that across
the interior region east of the Seamounts below the summit depth of the Seamounts. The Oyashio, which is also considered as
a compensation flow for the transport in the whole interior region, includes baroclinic as well as barotropic components.
Baroclinic transports in the whole interior region exceed those in the western boundary region in the upper (200–1000 m) and
lower (2000–5000 m) layers, and the total transport is northward (southward) in the upper (lower) layer. These excesses of
the baroclinic transport are balanced by a vertical transport of the meridional overturn. The meridional overturn has a complementary
relation to the basin-scale baroclinic circulation in the North Pacific subactic region.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
On the basis of the contemporary array of oceanographic and hydrometeorological data, we compute the characteristics of variations
of the Gulf-Stream transport in 1950–2004. The role played by the low-frequency oscillations of vorticity of the wind field
and turbulent heat fluxes in the North Atlantic in the formation of the analyzed variations is estimated. We reveal a significant
(on a 5% confidence level) positive linear trend of the monthly average Gulf-Stream transport manifested in the increase in
the Gulf-Stream transport by 13 Sv for the investigated period. On the basis of the established estimates, we make a conclusion
that about a quarter of the interannual variations of the Gulf-Stream transport is caused by the low-frequency oscillations
of vorticity of the wind field in the Subtropical Atlantic. Moreover, the Gulf-Stream transport is delayed relative to the
wind oscillations by about 2 yr. An important role in the changes in the Gulf-Stream transport is played by the response of
the system of west boundary currents to the quasiperiodic action of turbulent heat fluxes on the surface of the ocean connected
with the North-Atlantic Oscillation. The intensification of turbulent heat fluxes in the Northern Subpolar Cyclonic Gyre and
their weakening in the north part of the Subtropical Anticyclonic Gyre are accompanied by the intensification of the Gulf
Stream observed after 3–5 yr. The anomalies of turbulent heat fluxes of the opposite sign are followed by weakening of the
Gulf Stream also after a period of 3–5 yr. We also mention a potentially important role played the Pacific decadal oscillation
in maintaining the decadal variations of the intensity of Gulf Stream. The influence of this oscillation on the Gulf-Stream
transport is realized both via the changes in the wind field in different phases of oscillations and due to its influence
on the heat exchange of the ocean with the atmosphere. 相似文献
17.
Seasonal and interannual variability of the pressure field and indices of the North Atlantic atmosphere zonal circulation are analysed using historical (1894–1988) observations. It is shown that fluctuations of the index of North Atlantic oscillations (NAO) and that of the eastward transport give evidence of the interannual fluctuations with the typical time scale being 2–7 years. It is shown that the magnitude of interannual NAO index variability exceeds the typical magnitude of seasonal variations, particularly in winter. The time scale of NAO index variations and eastward transport coincides with the typicalEl Niño-southern oscillations (ENSO) temporal scale. The amplitudes of the annual, semi-annual harmonics, and high-frequency fluctuations of the NAO index increase during a typical ENSO event at least by a factor of 2.Translated by V. Puchkin. 相似文献
18.
We construct a one-dimensional nonstationary isopycnic model of vertical exchange in the Black Sea with regard for the processes
of draining and transformation of waters of the Sea of Marmara (or “plume”), vertical diffusion, and the action of winter
convection in the upper layer. It is assumed that mixing in the basin is local in space and time and that the winter wind
action remains constant from year to year in the analyzed version of the model. The temperature of the upper mixed layer introduced
to simulate the winter conditions is regarded as the principal external variable factor. Within the framework of the accepted
restrictions, the model enables us to study the annual and interannual variability of the thermohaline characteristics and
hydrochemical parameters in the water column of the sea. As an example, we perform the numerical analysis of the periodic
action of external thermal conditions on the characteristics of the system with a period of six years.
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Translated from Morskoi Gidrofizicheskii Zhurnal, No. 5, pp. 3–21, September–October, 2006. 相似文献
19.
We introduce the Northern Oscillation Index (NOI), a new index of climate variability based on the difference in sea level pressure (SLP) anomalies at the North Pacific High (NPH) in the northeast Pacific (NEP) and near Darwin, Australia, in a climatologically low SLP region. These two locations are centers of action for the north Pacific Hadley–Walker atmospheric circulation. SLPs at these sites have a strong negative correlation that reflects their roles in this circulation. Global atmospheric circulation anomaly patterns indicate that the NEP is linked to the western tropical Pacific and southeast Asia via atmospheric wave trains associated with fluctuations in this circulation. Thus the NOI represents a wide range of tropical and extratropical climate events impacting the north Pacific on intraseasonal, interannual, and decadal scales. The NOI is roughly the north Pacific equivalent of the Southern Oscillation Index (SOI), but extends between the tropics and extratropics. Because the NOI is partially based in the NEP, it provides a more direct indication of the mechanisms by which global-scale climate events affect the north Pacific and North America.The NOI is dominated by interannual variations associated with El Niño and La Niña (EN/LN) events. Large positive (negative) index values are usually associated with LN (EN) and negative (positive) upper ocean temperature anomalies in the NEP, particularly along the North American west coast. The NOI and SOI are highly correlated, but are clearly different in several respects. EN/LN variations tend to be represented by larger swings in the NOI. Forty percent of the interannual moderate and strong interannual NOI events are seen by the SOI as events that are either weak or opposite in sign. The NOI appears to be a better index of environmental variability in the NEP than the SOI, and NPH SLP alone, suggesting the NOI is more effective at incorporating the influences of regional and remotely teleconnected climate processes.The NOI contains alternating decadal-scale periods dominated by positive and negative values, suggesting substantial climate shifts on a roughly 14-year ‘cycle’. The NOI was predominantly positive prior to 1965, during 1970–1976 and 1984–1991, and since 1998. Negative values predominated in 1965–1970, 1977–1983, and 1991–1998. In the NEP, interannual and decadal-scale negative NOI periods (e.g. EN events) are generally associated with weaker trade winds, weaker coastal upwelling-favorable winds, warmer upper ocean temperatures, lower Pacific Northwest salmon catch, higher Alaska salmon catch, and generally decreased macrozooplankton biomass off southern California. The opposite physical and biological patterns generally occur when the index is positive. Simultaneous correlations of the NOI with north Pacific upper ocean temperature anomalies are greatest during the boreal winter and spring. Lagged correlations of the winter and spring NOI with subsequent upper ocean temperatures are high for several seasons. The relationships between the NOI and atmospheric and physical and biological oceanic anomalies in the NEP indicate this index is a useful diagnostic of climate change in the NEP, and suggest mechanisms linking variations in the physical environment to marine resources on interannual to decadal climate scales. The NOI time series is available online at: http://www.pfeg.noaa.gov. 相似文献
20.
The shortwave radiative forcings of smoke aerosol in the cloudless atmosphere during the summer fires of 2010 in European
Russia were quantitatively estimated for the land surface and the atmospheric upper boundary from measurement data obtained
at the Zvenigorod Scientific Station of the Obukhov Institute of Atmospheric Physics (OIAP ZSS), Russian Academy of Sciences.
Variations in the temperature of the surface air layer due to the smoke-induced attenuation of incoming solar radiation were
estimated. The most intensive smoke generation in the atmosphere was observed on August 7–9, 2010, when the maximum aerosol
optical thickness amounted to more than 4.0 at a wavelength of 550 nm. In this case, the albedo of single aerosol scattering
amounted to ∼0.95–0.96 and the asymmetry factor amounted to ∼0.69–0.70. The maximum shortwave radiative forcing of aerosol
amounted to about −360 W/m2 for the land surface and almost −150 W/m2 for the atmospheric upper boundary. During the period of intensive smoke generation, the cooling of the atmospheric surface
layer over daylight hours (12 h) amounted, on average, to ∼6°C. The power character of the dependence of the shortwave radiative
forcing of aerosol for the land surface on aerosol optical thickness up to its values exceeding 4.0, which was revealed earlier
on the basis of data on aerosol optical thickness (up to 1.5) obtained at the OIAP ZSS during the summer forest and peatbog
fires of 2002 in the region of Moscow, was supported. 相似文献