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1.
In this study, we used the National Centers for Environmental Prediction monthly sea surface temperature (SST) and surface
air temperature (SAT) data during 1982–1994 and the National Center for Atmospheric Research surface wind stress curl data
during 1982–1989 to investigate the Japan Sea SST temporal and spatial variabilities and their relations to atmospheric forcing.
First, we found an asymmetry in the correlation coefficients between SST and wind stress curl, which implies that the SST
variability at the scales of the order of one month is largely due to atmospheric forcing. Second, we performed three analyses
on the data fields: annual mean, composite analysis to obtain the monthly anomaly relative to the annual mean, and empirical
orthogonal function (EOF) analysis on the residue data relative to the summation of the annual mean and the monthly anomaly.
The first EOF mode of SST accounts for 59.9% of the variance and represents the Subpolar Front. The temporal variation of
the first EOF mode implies that the deep Japan Sea could be cooler in cold seasons (November–April) of 1984–1987. Third, we
computed cross-correlation coefficients among various principal components and found that the atmospheric warming/cooling
is the key factor causing intra-seasonal and interannual SST variabilities. 相似文献
2.
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
3.
To explore the causes of the winter shallow mixed layer and high sea surface temperature (SST) along the strong Kuroshio jet
from the East China Sea to the upstream Kuroshio extension (25.5°N–150°E) during 1988–1994 when the Japanese sardine stocks
collapsed, high-resolution ocean general circulation model (OGCM) hindcast data are analyzed with a bulk mixed layer model
which traces particles at the mixed layer base. The shallow mixed layer and high SST along the Kuroshio jet are mainly caused
by the acceleration of the Kuroshio current velocity and the reduction of the surface cooling. Because the acceleration reduces
the time during which the mixed layer is exposed to wintertime cooling, deepening and cooling of the winter mixed layer are
restricted. The weaker surface cooling due to less severe meteorological forcing also causes the shallow mixed layer and the
high SST. The impact of the strong heat transport along the Kuroshio extends to the southern recirculation gyre of the Kuroshio/Kuroshio
extension regions; previous indications that the Japanese sardine recruitment is correlated with the winter SST and the mixed
layer depth (MLD) in the Kuroshio extension recirculation region could be related to the velocity, SST, and MLD near the Kuroshio
axis which also could affect the variability of North Pacific subtropical water. 相似文献
4.
Seasonal evolution of surface mixed layer in the Northern Arabian Sea (NAS) between 17° N–20.5° N and 59° E-69° E was observed
by using Argo float daily data for about 9 months, from April 2002 through December 2002. Results showed that during April
- May mixed layer shoaled due to light winds, clear sky and intense solar insolation. Sea surface temperature (SST) rose by
2.3 °C and ocean gained an average of 99.8 Wm−2. Mixed layer reached maximum depth of about 71 m during June - September owing to strong winds and cloudy skies. Ocean gained
abnormally low ∼18 Wm−2 and SST dropped by 3.4 °C. During the inter monsoon period, October, mixed layer shoaled and maintained a depth of 20 to
30 m. November - December was accompanied by moderate winds, dropping of SST by 1.5 °C and ocean lost an average of 52.5 Wm−2. Mixed layer deepened gradually reaching a maximum of 62 m in December. Analysis of surface fluxes and winds suggested that
winds and fluxes are the dominating factors causing deepening of mixed layer during summer and winter monsoon periods respectively.
Relatively high correlation between MLD, net heat flux and wind speed revealed that short term variability of MLD coincided
well with short term variability of surface forcing. 相似文献
5.
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
6.
Seasonal and interannual variability of the Subtropical Countercurrent (STCC) in the western North Pacific are investigated
using observations by satellites and Argo profiling floats and an atmospheric reanalysis. The STCC displays a clear seasonal
cycle. It is strong in late winter to early summer with a peak in June, and weak in fall. Interannual variations of the spring
STCC are associated with an enhanced subtropical front (STF) below the surface mixed layer. In climatology, the SST front
induces a band of cyclonic wind stress in May north of the STCC on the background of anticyclonic curls that drive the subtropical
gyre. The band of cyclonic wind and the SST front show large interannual variability and are positively correlated with each
other, suggesting a positive feedback between them. The cyclonic wind anomaly is negatively correlated with the SSH and SST
below. The strong (weak) cyclonic wind anomaly elevates (depresses) the thermocline and causes the fall (rise) in the SSH
and SST, accelerating (decelerating) STCC to the south. It is suggested that the anomalies in the SST front and STCC in the
preceding winter affect the subsequent development of the cyclonic wind anomaly in May. Results from our analysis of interannual
variability support the idea that the local wind forcing in May causes the subsequent variations in STCC. 相似文献
7.
N. A. Bond J. M. Adams 《Deep Sea Research Part II: Topical Studies in Oceanography》2002,49(26):5869-5887
The atmospheric forcing of the Bering Sea over its eastern shelf is estimated using the 40-year record of daily data from the NCEP/NCAR Reanalysis. This data set includes estimates of the processes responsible for the atmospheric forcing, namely the surface fluxes of momentum, sensible and latent heat, and longwave and shortwave radiation, and therefore permits quantifying effects that previously could be inferred only from the large-scale nature of the flow. The forcing in 1995–1999 is described in detail using daily time series; historical context for these results is provided with seasonal averages for the years 1959–1999.The analysis for winter concentrates on aspects related to the formation and advection of sea ice. Results indicate that the presence of sea ice is strongly related to the net surface-heat fluxes as well as the cross-shelf component of the wind. The 40-year record lacks any discernible long-term trend in the winter forcing and response. There was a notably cold period in the early to middle 1970s, and a warm period from the late 1970s into the early 1980s, but conditions during the 1990s are similar to those in the late 1950s and 1960s.The analysis for the warm season focuses on the mechanisms responsible for the variability in SST warming. Much of the intraseasonal and interannual variability in this warming can be attributed to variations in the downward shortwave radiation (solar heating). The 40-year record does indicate a long-term trend toward increased solar heating, and reduced surface latent-heat fluxes (evaporative cooling). These changes have led to August SSTs in the 1990s that are roughly 1°C warmer than in the 1960s. 相似文献
8.
Repeated hydrographic casts, mooring time series and satellite sea surface temperature collected during the CANALES experiment (1996–98) are used to describe the thermohaline circulation in the Balearic Channels (western Mediterranean) and to analyze its variability. Mass transports are estimated by inverse calculations. The role played by each channel in the meridional water exchange is clarified: the Ibiza Channel funnels southward cool, saline, northern waters whereas the Mallorca Channel appears as the preferred route for the northward progression of warm, fresh, southern waters. A neat interannual trend is revealed by the continuous decrease of the amount of Western Mediterranean Intermediate Waters (WIW) brought by the Northern Current, reflecting the increase in temperature of the winter mixed layer in the northern Mediterranean that occurred each year between 1996 and 1998. A clear seasonal signal was also seen in the transport of the Northern Current which decreased from 1 to 1.4 Sv in winter to < 0.5 Sv in summer. The current intensified again in fall. A number of mesoscale eddies, from 20 to 70 km in size, most of them anticyclonic vortex eddies were brought by the unstable Northern Current, these eddies strongly perturbed the water exchange in the Ibiza Channel forcing retroflections of northern waters back to the north-east into the Balearic Current. These eddies either stayed stalled for several months in the Gulf of Valencia to the north of the channel, or were slowly funnelled southward through the channel narrows. A decreasing trend was observed in the mesoscale activity of the Northern Current between 1996 and 1998. Conversely, large, anticyclonic eddies, 150-km diameter, progressively invaded the Algerian Basin to the south of the channels in 1997–98 and forcing northward inflows (up to 0.75 Sv) of fresh and warm waters of Atlantic origin (AW) into the Mallorca Channel. The marked interannual differences observed in both northern and southern eddy activity may be linked to the interannual variability of the large scale thermohaline circulation. 相似文献
9.
Long-term variability in the intermediate layer of the eastern Japan Basin has been investigated to understand the variability
of water mass formation in the East Sea. The simultaneous decrease of temperature at shallower depths and oxygen increasing
at deeper depths in the intermediate layer took place in the late 1960’s and the mid-1980’s. Records of winter sea surface
temperatures and air temperatures showed that there were cold winters that persisted for several years during those periods.
Therefore, it was assumed that a large amount of newly-formed water was supplied to the intermediate layer during those cold
winters. Close analysis suggests that the formation of the Upper Portion of Proper Water occurred in the late 1960’s and the
Central Water in the mid-1980’s. 相似文献
10.
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
11.
Yu. V. Artamonov N. P. Bulgakov P. D. Lomakin E. A. Skripaleva 《Physical Oceanography》2006,16(5):299-311
We study the seasonal and interannual variations of the field of sea-surface temperature (SST) in the Southwest Atlantic on
the basis of the analysis of three data arrays, namely, the Levitus-Boyer-1994 hydrological array, the WOD-98 actual database,
and the data of satellite measurements of SST. We perform the comparative analysis of the amplitude-phase characteristics
of the annual course of the SST field and discuss the distinctive features of its seasonal and interannual variations. It
is shown that the results obtained by using different data arrays are in good agreement. The values of the coefficient of
linear correlation are equal to 0.7–0.9. It is discovered that the maximum seasonal variations of SST are observed in the
zone of confluence of the Falkland and Brasil Currents in the vicinities of the South Subtropical and Antarctic Polar fronts.
The minimum seasonal variations are recorded in the Antarctic region and in the Weddell Sea. The satellite data demonstrate
that the level of interannual variability is high in the zones of climatic fronts.
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Translated from Morskoi Gidrofizicheskii Zhurnal, No. 5, pp. 62–76, September–October, 2006. 相似文献
12.
The paper considers the thermohaline structure of Black Sea abyssal and near-bottom waters on the basis of exact measurements
recorded in recent years under the HYDROBLACK and COMSBLACK international projects. The surface water mass (along with the
cold mixed layer), the intermediate, abyssal, and near-bottom masses are identified. The upper boundary of deep waters is
defined as a depth level where the density ratio decreases down to 0.1 This depth roughly corresponds to the 900–1100 m depth
levels. Furthermore, the paper provides potential temperature and salinily values in the near-bottom layer, with an error
of, respectively, 0.002°C and 0.002‰, at most.
Translated by Vladimir A. Puchkin. 相似文献
13.
Seasonal Variation of Space/Time Statistics of Short-Term Sea Surface Temperature Variability in the Kuroshio Region 总被引：1，自引：0，他引：1
Spatial and temporal scales of sea surface temperature (SST) variations in the Kuroshio region have been investigated using a satellite-based one-year merged SST product. Targeting short-term variations with temporal scales of less than a year, decorrelation scales, which are defined as the e-folding scale of SST variability, have been derived as functions of regional positions and calendar months. We assumed that the autocorrelation function of SST has anisotropic Gaussian characteristics in the space-time domain. Resultant spatial and temporal decorrelation scales range from 1 to 3° and 2 to 3 days, respectively. They are strongly inhomogeneous, anisotropic and time-dependent. These characteristics are attributed to the oceanic and atmospheric disturbances. Spatial decorrelation scales are determined mainly by strong atmospheric forcing in the study region. In the area with dominant atmospheric forcing, the spatial scales are larger than those in the other regions. Those in the regions with dynamical oceanographic disturbances are as small as 1°. Signal-to-noise ratios are also large where the atmospheric forcing is strong, while they are small where the oceanic signals are active. 相似文献
14.
Interdecadal modulation of interannual atmospheric and oceanic variability over the North Pacific 总被引：1，自引：0，他引：1
The interdecadal modulation of interannual variability of the atmosphere and ocean is examined over the North Pacific by using Wavelet Transform combined with Empirical Orthogonal Function (EOF) or Singular Value Decomposition (SVD) analysis. For the period of record 1899–1997, the interannual variability of the wintertime Aleutian Low, identified by either the North Pacific Index or the leading eigenvector (EOF-1) of North Pacific sea level pressure (SLP), exhibits an interdecadal modulation. Interannual variance in the strength of the Aleutian Low was relatively large from the mid-1920s to mid-1940s and in the mid-1980s, but relatively small in the periods from 1899 to the mid-1920s and from the mid-1940s to the mid-1970s. The periods of high (low) interannual variability roughly coincide with pentadecadal regimes having a time averaged relatively intense (weak) Aleutian Low. Consistent with this SLP variability the interannual variance in the zonal wind stress is strengthened in the central North Pacific after the 1970s. The SLP EOF-2, which is related to the North Pacific Oscillation, exhibited a strengthening trend from the beginning of this century to the mid-1960s. After the 1970s, the interannual variance of SLP EOF-2 is generally smaller than that in the period from 1930 to 1970. Similar interdecadal changes in interannual variance are found in expansion coefficients for the first two EOFs of the Pacific sector 500 hPa height field for the period 1946–1993. EOF-1 of Pacific sector 500 hPa corresponds to the Pacific/North American (PNA) teleconnection pattern, while EOF-2 is related to the Western Pacific (WP) pattern. The relative influence of the atmospheric PNA and WP interannual variability on North Pacific SSTs appears to have varied at pentadecadal time scales. Results from an SVD analysis of winter season (December–February) 500 hPa and North Pacific spring season (March–May) SST fields demonstrate that the PNA-related SST anomaly exhibited larger interannual variance after the 1970s, whereas the interannual variance of the WP related SST anomaly is larger before the 1970s. Correlations between the coastal North Pacific SST records and gridded atmospheric field data also change on interdecadal time scales. Our results suggest that the SST records from both the northwest and northeast Pacific coasts were more closely coupled with the PNA teleconnection pattern during the periods of 1925–1947 and 1977–1997 than in the regime from 1948 to 1976. Teleconnections between ENSO and preferred patterns of atmospheric variability over the North Pacific also appear to vary on interdecadal time scales. However, these variations do not reflect a unique regime-dependent influence. Our results indicate that ENSO is primarily related to the PNA (WP) pattern in the first (last) half of the present century. Correlation coefficients between indices for ENSO and PNA-like atmospheric variability are remarkably weak in the period from 1948 to 1976. 相似文献
15.
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
16.
The paper discusses the data derived from a numerical experiment on the ocean’s response (between the equator and 64°N) to
the seasonal variability of the atmospheric forcing (wind and heat flux through the ocean surface). A multilayer (7 layers)
non-linear model is used incorporating the upper mixed layer interacting with the internal layers in the regimes of entraining
and subduction. The restructuring of the layer composition, the currents and temperature variability, as well as the alternation
of the entrainment and subduction regimes are analysed.
Translated by Vladimir A. Puchkin. 相似文献
17.
The seasonal variability of sonic layer depth (SLD) in the central Arabian Sea (CAS) (0 to 25°N and 62-66°E) was studied using
the temperature and salinity (T/S) profiles from Argo floats for the years 2002–2006. The atmospheric forcing responsible
for the observed changes was explored using the meteorological data from NCEP/NCAR and Quickscat winds. SLD was obtained from
sound velocity profiles computed from T/S data. Net heat flux and wind forcing regulated SLD in the CAS. Up-welling and down-welling
(Ekman dynamics) associated with the Findlater Jet controlled SLD during the summer monsoon. While in winter monsoon, cooling
and convective mixing regulated SLD in the study region. Weak winds, high insolation and positive net heat flux lead to the
formation of thin, warm and stratified sonic layer during pre and post summer monsoon periods, respectively. 相似文献
18.
Sea surface temperature(SST) measurements from 26 coastal hydrological stations of China during 1960–2015 were homogenized and analyzed in this study. The homogenous surface air temperature(SAT) series from meteorological stations which were highly correlated to SST series was used to construct the reference series.Monthly mean SST series were then derived and subjected to a statistical homogeneity test, called penalized maximal t test. Homogenized monthly mean SST series were obtained by adjusting all significant change points which were supported by historic metadata information. Results show that the majority of break points are caused by instrument change and station relocation, which accounts for about 61.3% and 24.2% of the total break points,respectively. The regionally averaged annual homogeneous SST series from the 26 stations shows a warming trend(0.19°C per decade). This result is consistent with that based on the homogenized annual mean SAT at the same region(0.22°C per decade), while the regionally averaged mean original SST series from the same stations shows a much weaker warming of 0.09°C per decade for 1960–2015. This finding suggests that the effects of artificial change points on the result of trend analysis are remarkable, and the warming rate from original SST observations since 1960 may be underestimated. Thus a high quality homogenized observation is crucial for robust detection and assessment of regional climate change. Furthermore, the trends of the seasonal mean homogenized SST were also analyzed. This work confirmed that there was an asymmetric seasonal temperature trends in the Chinese coastal water in the past decades, with the largest warming rate occurring in winter. At last,the significant warming in winter and its relationships to the variability of three large-scale atmospheric modes were investigated. 相似文献
19.
The mean seasonal cycle of mixed layer depth (MLD) in the extratropical oceans has the potential to influence temperature, salinity and mixed layer depth anomalies from one winter to the next. Temperature and salinity anomalies that form at the surface and spread throughout the deep winter mixed layer are sequestered beneath the mixed layer when it shoals in spring, and are then re-entrained into the surface layer in the subsequent fall and winter. Here we document this ‘re-emergence mechanism’ in the North Pacific Ocean using observed SSTs, subsurface temperature fields from a data assimilation system, and coupled atmosphere–ocean model simulations. Observations indicate that the dominant large-scale SST anomaly pattern that forms in the North Pacific during winter recurs in the following winter. The model simulation with mixed layer ocean physics reproduced the winter-to-winter recurrence, while model simulations with observed SSTs specified in the tropical Pacific and a 50 m slab in the North Pacific did not. This difference between the model results indicates that the winter-to-winter SST correlations are the result of the re-emergence mechanism, and not of similar atmospheric forcing of the ocean in consecutive winters. The model experiments also indicate that SST anomalies in the tropical Pacific associated with El Niño are not essential for re-emergence to occur.The recurrence of observed SST and simulated SST and SSS anomalies are found in several regions in the central North Pacific, and are quite strong in the northern (>50°N) part of the basin. The winter-to-winter autocorrelation of SSS anomalies exceed those of SST, since only the latter are strongly damped by surface fluxes. The re-emergence mechanism also has a modest influence on MLD through changes in the vertical stratification in the seasonal thermocline. 相似文献
20.
The paper discusses the results of numerical experiments on response of the Black Sea to the ‘real’ (mean monthly) atmospheric
forcing. A new version of the multi-layer quasi-isopycnic model is applied which does not use the rigid-lid approximation
and allows for a salt flux through the sea surface. Ways of obtaining quantitative agreement between the calculated data due
only to the external forcing, without invokingin situ temperature/salinity observations are suggested.
Translated by Vladimir A. Puchkin. 相似文献