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1.
北太平洋海表温度及各贡献因子的变化 总被引：2，自引：0，他引：2
采用1958年1月至2007年12月SODA海洋上层温度的月平均资料,基于海温变化方程和统计分析方法,分析了北太平洋海表面温度(SST)异常特征及各局地因子贡献比例的变化。结果表明,伴随着1976/1977风场最强中心位置的南北移动,形成了两个北太平洋SST年际-年代际变化的异常中心:一个是位于30°N附近的副热带海盆内区,SST异常主要受风应力强度的主导;一个是位于40°N附近的副热带和副极地环流交汇区,SST异常主要受风应力旋度的位置即风场位置的影响。在副热带海盆内区,最强降温发生在1978-1982年,SST异常的主要局地贡献因子为海表热通量和经向平流,二者所占比例和约为50%~60%,均为同相增温或降温作用,余项所占比例约为20%~50%。在副热带和副极地环流交汇区,海盆内区和西部边界区的SST异常的跃变时间同为1975年,但是内区的垂直混合项的跃变时间早于西部5年左右。SST异常的主要贡献因子为海表热通量和经向平流,但在1983-1988年海温强降温期间,经向平流项贡献大于海表热通量项的贡献。两个区域的垂直混合项均为降温贡献,虽然量值小却显示出很强的年代际变化信号。平流项中经向平流最大,垂直平流最小。 相似文献
2.
ORA-S3 oceanological reanalysis data for 1959–2011 is applied to analyze the role different factors play in forming advective heat transfer anomalies on an interannual–decadal scale in the upper mixed layer of the North Atlantic. Regions are revealed in which horizontal heat advection anomalies are determined by variations in current intensity, temperature gradients, and their joint influence. It is demonstrated that the contribution of different mechanisms responsible for advective heat transfer anomalies in the upper mixed layer to the total anomalies of advective origin varies fundamentally from one current to another in the North Atlantic. In the Gulf Stream area (after it separates from the continental slope), horizontal heat advection anomalies in the upper mixed layer result mainly from fluctuations in current intensity, while in the Caribbean Current and the Gulf Stream area (until its separation), they result from variations in the horizontal temperature gradients in the upper mixed layer. In the Labrador Current, both of these mechanisms have the same sign and approximately the same absolute values. In the East Greenland Current, they compensate each other. The contribution of anomalies in horizontal temperature gradients transferred by anomalous currents to the formation of heat transfer anomalies in the upper layer of the North Atlantic are, on the whole, relatively small throughout the water area. The areas of the North Atlantic and West Greenland currents are exceptions. 相似文献
3.
Seasonal variability of interannual fluctuations of the heat balance components of the upper quasi-homogeneous ocean layer (UQL) in the North Atlantic is analyzed by processing the reanalysis data set for the period of 1959–2011. It is shown that interannual variations in the components of the UQL heat budget are characterized by pronounced regional features in all seasons. In the tropics and subtropics, heat balance is quasistationary and is determined by the nonlocal processes, such as heat advection and horizontal mixing. In the subpolar latitudes, nonstationarity (in the spring) and heat fluxes at the UQL boundary (in the autumn and in the winter) are also important. A major role in the interannual variability of the UQL temperature in the vicinity of jet currents of the Gulf Stream type is played in all seasons by the fluctuations of horizontal heat advection. However, the contribution of interannual fluctuations of the individual components of the heat budget to variability of the UQL temperature varies considerably in different seasons. The interannual fluctuations of the local variation in the UQL temperature are characterized by the largest variability in the spring and the lowest one in the autumn. The greatest contribution of the variations in the horizontal heat advection to the change in the UQL temperature at the interannual scale is recorded in the winter, and the lowest one is in the summer. The contribution of the interannual variations in the heat fluxes at the UQL upper boundary to the variability of the UQL temperature is the highest in the summer and the lowest in the autumn. Fluctuations of the heat fluxes at the UQL lower boundary do not have a significant impact on the interannual variations in the UQL temperature for the whole water area. The exception is small areas in the region of the formation of the North Atlantic deep water in the autumn–winter period and in the vicinity of the Equatorial Counter Current in the spring–summer period. 相似文献
4.
Interdecadal climate regime dynamics in the North Pacific Ocean: theories, observations and ecosystem impacts 总被引：2，自引：0，他引：2
Basin-scale variations in oceanic physical variables are thought to organize patterns of biological response across the Pacific Ocean over decadal time scales. Different physical mechanisms can be responsible for the diverse basin-scale patterns of sea-surface temperature (SST), mixed-layer depth, thermocline depth, and horizontal currents, although they are linked in various ways. In light of various theories and observations, we interpret observed basinwide patterns of decadal-scale variations in upper-ocean temperatures. Evidence so far indicates that large-scale perturbations of the Aleutian Low generate temperature anomalies in the central and eastern North Pacific through the combined action of net surface heat flux, turbulent mixing and Ekman advection. The surface-forced temperature anomalies in the central North Pacific subduct and propagate southwestwards in the ocean thermocline to the subtropics but apparently do not reach the equator. The large-scale Ekman pumping resulting from changes of the Aleutian Low forces western-intensified thermocline depth anomalies that are approximately consistent with Sverdrup theory. These thermocline changes are associated with SST anomalies in the Kuroshio/Oyashio Extension that are of the same sign as those in the central North Pacific, but lagged by several years. The physics of the possible feedback from the SST anomalies to the Aleutian Low, which might close a coupled ocean–atmosphere mode of decadal variability, is poorly understood and is an area of active research. The possible responses of North Pacific Ocean ecosystems to these complicated physical patterns is summarized. 相似文献
5.
根据一套客观分析潜热通量、基于绕岛理论诊断的南海贯穿流(LST)、南海热含量等月平均资料,分析南海表层潜热通量的年际和年代际变化特征。南海地区的潜热通量冬季强,春季的潜热通量弱;在秋冬季节,南海北部的潜热通量远大于南部;夏季南海潜热通量南部高于北部;从20世纪80年代初潜热通量逐渐增加。使用EOF经验正交分解,M-K检验方法分析南海潜热通量的多时间尺度变化,前3个模态的方差贡献率分别为:53.01%(主要为长期趋势)、17.4%(年代际变化)、6.71%(年际变化)。分析表明在年际尺度上南海贯穿流(LST)减少导致南海海表温度(SST)增温幅度上升,海气温差比湿差减小,从而导致潜热释放减少,潜热通量呈负异常;反之LST进入南海增多,海气温差比湿差变大,导致南海潜热损失减少,潜热通量呈正异常。 相似文献
6.
南海潜热交换年际与年代际变化的分析探讨 总被引：1，自引：0，他引：1
根据一套客观分析潜热通量、基于绕岛理论诊断的南海贯穿流(LST)、南海热含量等月平均资料,分析南海表层潜热通量的年际和年代际变化特征。南海地区的潜热通量冬季强,春季的潜热通量弱;在秋冬季节,南海北部的潜热通量远大于南部;夏季南海潜热通量南部高于北部;从20世纪80年代初潜热通量逐渐增加。使用EOF经验正交分解,M-K检验方法分析南海潜热通量的多时间尺度变化,前3个模态的方差贡献率分别为:53.01%(主要为长期趋势)、17.4%(年代际变化)、6.71%(年际变化)。分析表明在年际尺度上南海贯穿流(LST)减少导致南海海表温度(SST)增温幅度上升,海气温差比湿差减小,从而导致潜热释放减少,潜热通量呈负异常;反之LST进入南海增多,海气温差比湿差变大,导致南海潜热损失减少,潜热通量呈正异常。 相似文献
7.
Muyin Wang Nicholas A. Bond James E. Overland 《Deep Sea Research Part II: Topical Studies in Oceanography》2007,54(23-26):2543
A comparative analysis was conducted on climate variability in four sub-arctic seas: the Sea of Okhotsk, the Bering Sea shelf, the Labrador Sea, and the Barents Sea. Based on data from the NCEP/NCAR reanalysis, the focus was on air–sea interactions, which influence ice cover, ocean currents, mixing, and stratification on sub-seasonal to decadal time scales. The seasonal cycles of the area-weighted averages of sea-level pressure (SLP), surface air temperature (SAT) and heat fluxes show remarkable similarity among the four sub-arctic seas. With respect to variation in climate, all four seas experience changes of comparable magnitude on interannual to interdecadal time scales, but with different timing. Since 2000 warm SAT anomalies were found during most of the year in three of the four sub-arctic seas, with the exception of the Sea of Okhotsk. A seesaw (out of phase) pattern in winter SAT anomalies between the Labrador and the Barents Sea in the Atlantic sector is observed during the past 50 years before 2000; a similar type of co-variability between the Sea of Okhotsk and the Bering Sea shelf in the Pacific is only evident since 1970s. Recent positive anomalies of net heat flux are more prominent in winter and spring in the Pacific sectors, and in summer in the Atlantic sectors. There is a reduced magnitude in wind mixing in the Sea of Okhotsk since 1980, in the Barents Sea since 2000, and in early spring/late winter in the Bering Sea shelf since 1995. Reduced sea-ice areas are seen over three out of four (except the Sea of Okhotsk) sub-arctic seas in recent decades, particularly after 2000 based on combined in situ and satellite observations (HadISST). This analysis provides context for the pan-regional synthesis of the linkages between climate and marine ecosystems. 相似文献
8.
全球海洋环流模式中上层海洋对表面强迫的响应和调整Ⅱ.年代际变率 总被引：6，自引：1，他引：5
利用一个较高分辨率的全球海洋环流模式在COADS 1945～1993年逐月平均资料的强迫下对海温和环流场进行了模拟,分析了北太平洋海温和环流场的年代际变化特征,同时诊断了1976-77年代际跃变过程中海温场变化的机制.模式模拟出了北太平洋海温年代际异常的主要模态以及1976-77年跃变前后的演变特征,模拟的北太平洋中部、加州沿岸和KOE区的海温异常的强度和演变趋势均和观测比较一致;同时,模式重现了分别始于20世纪70和80年代的中纬度海温异常信号沿等密度面向低纬地区的两次潜沉过程.在表层,流场的异常主要表现为与风应力异常基本符合Ekman关系的一个异常海洋涡旋,而整个上层海洋平均的流场异常则表现为两个海洋涡旋的异常,其中副热带海洋涡旋的异常的强度要显著于副极地海洋涡旋的异常,而副极地海洋涡旋异常出现的时间比副热带海洋涡旋晚3a左右的时间.对1976-77年前后3个区域上层海温各贡献项的诊断结果表明,北太平洋中部变冷主要是水平平流和热通量异常贡献的结果;而加州沿岸变暖主要归因于热通量的贡献;在KOE区,垂直平流、热通量和水平平流三者都起了重要作用,其中水平平流异常对这一区域海温年代际跃变出现的时间起了至关重要的作用. 相似文献
9.
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
10.
Various statistical methods (empirical orthogonal function (EOF), rotated EOF, singular value decomposition (SVD), principal
oscillation pattern (POP), complex EOF (CEOF) and joint CEOF) were applied to low-pass filtered (>7 years) sea surface temperature
(SST), subsurface temperature and 500 hPa geopotential height in order to reveal standing and propagating features of decadal
variations in the North Pacific. Four decadal ocean-atmosphere covariant modes were found in this study. The first mode is
the well-known ENSO-like mode associated with the “Pacific-North American” atmospheric pattern, showing SST variations reversed
between the tropics and the extratropics. In the western tropical Pacific, subsurface temperature variations were found to
be out of phase with the SST variations. The other three modes are related to the oceanic general circulation composed of
the subtropical gyre, the Alaskan gyre and the subpolar gyre, respectively. The 1988/89 event in the northern North Pacific
was found to be closely associated with the subtropical gyre mode, and the atmospheric pattern associated with this mode is
the Arctic Oscillation. An upper ocean heat budget analysis suggests that the surface net heat flux and mean gyre advection
are important to the Alaskan gyre mode. For the subpolar gyre mode, the mean gyre advection, local Ekman pumping and surface
net heat flux play important roles. Possible air-sea interactions in the North Pacific are also discussed. The oceanic signals
for these decadal modes occupy a thick layer in the North Pacific, so that accumulated heat content may in turn support long-term
climate variations.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
11.
对海洋中起伏运动(heaving)信号的时空分布研究能够帮助我们更好地了解气候系统中的年际和年代际变率。文章通过再分析资料和模式对太平洋区域的heaving主要模态进行了研究。研究结果表明: 太平洋区域主要存在两种heaving模态: 第一模态主要表现为赤道东西两侧的温跃层异常信号反位相; 第二模态表现为赤道区域和副热带区域的温跃层异常信号呈现反位相变化的规律。本文对这两个主要heaving模态所涉及的物理过程进行详细讨论, 结果表明: 东西反位相模态主要是受赤道波动调节的结果; 而经向结构模态则主要是由赤道地区的波动和副热带区域的风应力旋度异常作用共同导致。此外, 我们还讨论了heaving模态可以通过海洋波动以及Ekman输送等过程对海盆尺度的热输送(振幅约为5×1014W)以及海洋热含量(振幅约为1.5×1020J)的再分配起到了关键的调制作用, 进一步表明heaving模态对全球气候变化有着重要的作用。 相似文献
12.
Based on the data on the sea-surface temperature (SST), the heat content of the upper 200-m layer, and the sea-level pressure, we analyze the low-frequency variability of the SST and heat content in the North Atlantic in 1950–1992 and the index of North-Atlantic Oscillation (NAO) in 1940–1995. It is confirmed that the role of the ocean and various mechanisms controlling the variability of SST changes for processes corresponding to different time scales (interannual, decadal, and interdecadal). It is shown that the interaction of tropical and subtropical latitudes is of principal importance on the interannual scale, the processes regulating the variability of subtropical gyre are important on the decadal scale, and the variations of the NAO with lower frequencies are controlled by the oceanic variability at high latitudes. We discuss possible feedbacks in the ocean–atmosphere system maintaining the NAO. 相似文献
13.
Decadal-to-interdecadal response and adjustment of the North Pacific to prescribed surface forcing in an oceanic general circulation model 总被引：2，自引：0，他引：2
1IntroductionAvariety of observational evidences have shownthe existence of decadal-to-interdecadal variabilitiesin the Pacific Ocean.The phase transition for thosevariabilities could be gradual or abrupt.A strikingexample for abrupt change is the so-call… 相似文献
14.
A close correlation is found between dynamic processes in the near-earth tropical atmosphere, conditioned by air pressure anomalies in the Azor maximum, and the inter-annual ocean surface temperature variability in the north equatorial current area and in some other areas of the North Atlantic. A regression relation is proposed for calculating the sea surface temperature from the air pressure maximum in the Azor maximum. We discuss the anomalously high (low) upper ocean layer temperatures in the north equatorial current area induced by dynamic anomalies in the near-earth atmosphere and by the bottom topography.Translated by V. Puchkin. 相似文献
15.
16.
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.
__________
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 6, pp. 59–75, November–December, 2007. 相似文献
17.
C. J. C. REASON 《地球，A辑:动力气象学与海洋学》2000,52(2):203-223
Observations of multidecadal variability in sea surface temperature (SST), surface air temperature and winds over the Southern Hemisphere are presented and an ocean general circulation model applied towards investigating links between the SST variability and that of the overlying atmosphere. The results suggest that the dynamical effect of the wind stress anomalies is significant mainly in the neighbourhood of the western boundary currents and their outflows across the mid‐latitudes of each Southern Hemisphere basin (more so in the South Indian and South Atlantic than in the South Pacific Ocean) and in the equatorial upwelling zones. Over most of the subtropics to mid‐latitudes of the Southern Hemisphere oceans, changes in net surface heat flux (particularly in latent heat) appear to be more important for the SST variability than dynamical effects. Implications of these results for modelling and understanding low frequency climate variability in the Southern Hemisphere as well as possible links with mechanisms of decadal/interdecadal variability in the Northern Hemisphere are discussed. 相似文献
18.
Different physical mechanisms which cause interannual and interdecadal temperature anomalies in the upper mixed layer (UML) of the North Atlantic are investigated using the data of ORA-S3 reanalysis for the period of 1959–2011. It is shown that the annual mean heat budget in UML is mainly caused by the balance between advective heat transfer and horizontal turbulent mixing (estimated as a residual term in the equation of thermal balance). The local UML temperature change and contribution from the heat fluxes on the lower boundary of the UML to the heat budget of the upper layer are insignificant for the time scale under consideration. The contribution of the heat fluxes on the upper UML boundary to the low-frequency variability of the upper layer temperature in the whole North Atlantic area is substantially less than 30%. Areas like the northwestern part of the Northern Subtropical Anticyclonic Gyre (NSAG), where their contribution exceeds 30–60%, are exceptions. The typical time scales of advective heat transfer variability are revealed. In the NSAG area, an interannual variability associated with the North Atlantic Oscillation dominates, while in the North Atlantic subpolar gyre, an interdecadal variability of advective transfers with periods of more than 30 years prevails. 相似文献
19.
Sea level variations in the regional seas around Taiwan 总被引：2，自引：0，他引：2
The patterns and trends of sea level rise in the regional seas around Taiwan have been investigated through the analyses of
long-term tide-gauge and satellite altimetry data. Series of tide-gauge data extending over 50 years reveal decadal and interannual
variations and spatially-inhomogeneous patterns of generally rising sea level. The East Asia tide-gauge stations around Taiwan
show an average trend of +2.4 mm/yr from 1961–2003, which is larger than the reported global rate of +1.8 mm/yr for the same
period. These stations also show significantly larger sea level rise rates (+5.7 mm/yr) than global values (+3.1 mm/yr) during
the period from 1993–2003. Consistent with the coastal tide-gauge records, satellite altimetry data show similar increasing
rates (+5.3 mm/yr) around Taiwan during the same period. Comparisons with temperature anomalies in the upper ocean suggest
that thermal expansion and heat advection in the upper layer contribute significantly to the long-term sea level variations
in this area with correlations >0.9 for observations after 1992. Thermosteric sea level variations may also explain the interannual
and decadal variations of the observed sea level rises around Taiwan. Our analysis also indicates that the altimetry data
are only part of a long-term, larger-scale signal. Finally, we have found that a non-linear smoother, LOESS, is more suitable
for extracting long-term trends in sea level than the traditional linear regression approach. 相似文献