1994年西太平洋副高异常的前期特征分析

本文通过相关普查，分析了影响夏季西太平洋副热带高压的北太平洋海温场和北半球５００ｈＰａ高度场的前期特征，找出了影响１９９４夏季酉太平洋副热带高压异常的强信号及其所在区域．以较高的信度和精度建立了夏季逐月副高强度和脊线位置两特征量的预报方程，进一步发现，中、东部太平洋海温场存在与副高强度高相关的对偶相关区，该区同前一年６月加利福尼亚寒流和北赤道暖流间形成的海温梯度相对应，而初夏副高脊线位置则决定于前一年１０～１２月赤道东太平洋一线的海温分布．     

北太平洋海温分布与7月副高的遥相关分析

选取1952-2005年共54 a北太平洋月平均海表温度(SST)资料,奇异值分解结果表明,6月日界线附近西风漂流区的SST包含了北太平洋SST场的主要信息,西风漂流区与赤道冷水区的SST存在遥相关振荡,并且在6月振幅达全年最高值,11月其振幅出现次高值。分析结果表明,6月西风漂流区的SST可视为来年7月西太平洋副高强弱变化的信号:6月西风漂流区的SST偏低,则来年7月西太平洋副高偏强;反之,来年7月西太平洋副高偏弱。     

北太平洋冬季SST、风场及环流对淡水强迫的响应

通过海气耦合模式CCSM3(The Community Climate System Model version 3),研究在北大西洋高纬度淡水强迫下,北太平洋冬季的海表温度SST、风场及流场的响应及其区域性差异。结果表明:淡水的注入使北太平洋整体变冷,但有部分区域异常增暖;在太平洋东部赤道两侧,SST的变化出现北负南正的偶极子型分布。阿留申低压北移的同时中纬度西风减弱,热带附近东北信风增强。黑潮和南赤道流减弱,北太平洋副热带逆流和北赤道流增强,日本海被南向流控制。风场及流场的改变共同导致了北太平洋SST异常出现复杂的空间差异:北太平洋中高纬度SST的降温主要由大气过程决定,海洋动力过程主要影响黑潮、日本海及副热带逆流区域的SST,太平洋热带地区SST异常由大气与海洋共同主导。     

黄、渤海海冰长期变化特征分析

选取渤海、黄海北部冰情等级、冰面积资料和大气环流逐月资料,采用小波分析和交叉小波分析方法,研究海冰长期变化特征及其气候成因。结果发现黄、渤海海冰具有多尺度变化特征,存在低频变化、高频变化和无明显周期的演变过程。西太平洋副高、亚洲极涡以及纬向环流是影响海冰生成与变化的直接因素。黄、渤海海冰还与印度洋副高、北美副高,以及大西洋副高存在显著年代际相关关系。     

CHARACTERISTICS ON INTERANNUAL VARIATIONS OF NORTH PACIFIC SST AND ITS RELATION TO EAST ASIA CLIMATE

The interannual variations of the monthly sea surface temperature (SST) in the North Pacific (including Equatorial East Pacific) during 1951-1980 are analysed by means of EOF method. The findings are:(1) In the cold and warm ocean current areas, such as the North Pacific Current, the California Current and the Equatorial East Pacific areas, the convergence speeds are the fastest, while in the Kuroshio and the western part of the North Equatorial Current areas they are fast only in winter.(2) The physical features of the first 3 eigenvectors are obvious. The first eigenvector shows that the SST values are high in the south and low in the north in the latitudinal distribution of the SST field. The warm current area, i.e. the northwestern part of the North Pacific is positive and the cold current area, i.e. the southeastern part of the North Pacific including the Eastern Equatorial Pacific is negative. The zero line of the 2nd eigenvector field runs from northeast to southwest, in the same direction as the     

印度洋海温异常对西北太平洋台风的影响及机制研究

基于近40 a NCEP/NCAR再分析月平均高度场、风场、涡度场、垂直速度场以及NOAA重构的海面温度(sea surface temperature,SST)资料和美国联合台风预警中心(Joint Typhoon Warning Center,JTWC)热带气旋最佳路径资料,利用合成分析方法,研究了前期春季及同期夏季印度洋海面温度同夏季西北太平洋台风活动的关系。结果表明:1)前期春季印度洋海温异常(sea surface temperature anomaly,SSTA)尤其是关键区位于赤道偏北印度洋和西南印度洋地区对西北太平洋台风活动具有显著的影响,春季印度洋海温异常偏暖年,后期夏季,110°～180°E的经向垂直环流表现为异常下沉气流,对应风场的低层低频风辐散、高层辐合的形势,这种环流形势使得低层水汽无法向上输送,对流层中层水汽异常偏少,纬向风垂直切变偏大,从而夏季西北太平洋台风频数偏少、强度偏弱,而异常偏冷年份则正好相反。2)春季印度洋异常暖年,西北太平洋副热带高压加强、西伸;而春季印度洋异常冷年,后期夏季西北太平洋副热带高压减弱、东退,这可能是引起夏季西北太平洋台风变化的另一原因。     

全球变暖背景下最近40年太平洋海温变化数值模拟

用Non-Boussinesq POP模式和1960—1999年NCEP的1 000 hPa大气温度和风场资料,模拟了最近40 a太平洋海温的变化,通过与实际观测结果比较,得出模拟结果是可信的,并且得到了一些有意义的结果:在海面,太平洋最大的增温发生在赤道中东太平洋,即Niño1-Niño4区内,最大的降温在中纬度南北太平洋中部,除了北半球太平洋西岸40°N附近为降温外,在北半球太平洋沿岸基本上为升温,但太平洋东海岸的升温幅度要远大于西海岸;在太平洋0~483 m深度垂直方向,除了赤道中太平洋区域海温的变化在海面为上升,在169 m处为下降,在483 m处又转为上升外,其他区域海温的变化在垂直方向基本上为线性变化。在全球增暖的背景下,虽然El Niño现象在20世纪90年代以后表现出增强的趋势,但是反映在赤道表面以下的次表层西太平洋暖池中的异常暖中心,在由西向东移动过程中其强度却是减弱的。     

热带太平洋海温异常对北极海冰的可能影响

本文利用1950-2015年间Hadley环流中心海冰和海温资料及NCEP/NCAR再分析资料,研究了热带太平洋海温异常对北极海冰的可能影响,并从大气环流和净表面热通量两个角度探讨了可能的物理机制。结果表明,在ENSO事件发展年的夏、秋季节,EP型与CP型El Niño事件与北极海冰异常的联系无明显信号。而La Niña事件期间北极海冰出现显著异常,并且EP型与CP型La Niña之间存在明显差异。EP型La Niña发生时,北极地区巴伦支海、喀拉海关键区海冰异常减少,CP型La Niña事件则对应着东西伯利亚海、楚科奇海地区海冰异常增加。在EP型La Niña发展年的夏、秋季节,热带太平洋海温异常通过遥相关波列,使得巴伦支海、喀拉海海平面气压为负异常并与中纬度气压正异常共同构成类似AO正位相的结构,形成的风场异常有利于北大西洋暖水的输入,同时造成暖平流,偏高的水汽含量进一步加强了净表面热通量收入,使得巴伦支海、喀拉海海冰异常减少。而在CP型La Niña发展年的夏季,东西伯利亚海、楚科奇海关键区受其东侧气旋式环流的影响,以异常北风分量占主导,将海冰从极点附近由北向南输送到关键区,海冰异常增加,而净表面热通量的作用较小。     

北太平洋海温场的时空特征分析

近年来运用海表温度作副热带高压和长期天气预报方面取得了显著效果,为了进一步探讨海洋对气候和长期天气过程的影响,必须重视海温场的特征分析。这几年已有一些工作[1,3,7],从不同侧面对北太平洋海温场进行研究。本文试图从海—气相互作用的角度分析北太平洋海温场的时空分布特征及其年际变动,进而讨论它们对大气的影响。     

Linkage between winter air temperature over the subtropical Western Pacific and the ice extent anomaly in the Sea of Okhotsk

This study deals with the correlation between ice extent in the Sea of Okhotsk and the interannual variability of winter (December–February) air temperature over the subtropical Western Pacific from 1979 to 2008. The analysis indicates that the increase in sea ice extent coincides not only with cooling over the Sea of Okhotsk and the adjacent area, but also with significant warming over the subtropical Western Pacific that extends from the surface to the middle troposphere. This meridional dipole pattern of tropospheric temperature anomalies (cooling in the high latitudes and warming in the low latitudes) primarily results from dynamical processes driven by the large-scale atmospheric circulation change. A heat budget diagnosis reveals that when ice extent in the Sea of Okhotsk increases by one standard deviation, the tropospheric air temperature over the subtropical Western Pacific rises by about 0.25°C. It also suggests that the adiabatic heating and stationary eddy heat flux convergence may be the most important factors, which account for 30 and 15% of the warming, respectively. In addition, these two factors also coordinate to result in significant cooling over the Sea of Okhotsk and the adjacent regions.     

北太平洋海温与南方涛动的相关分析

有关热带太平洋的海洋学和气象学近年来已列为理论和“诊断”研究的课题之中。从事这方面的大量工作是探讨埃尔尼诺和南方涛动(SO)相互作用的复杂机理问题。本文着重讨论南方涛动与北太平洋海温相关场的时滞关系以及它们的时空变化,表明在不同海域、不同季节中都存在较大的差异。     

Altimeter-derived surface circulation in the large-scale NE Pacific Gyres. : Part 2: 1997–1998 El Niño anomalies

Changes in the sea surface heights (SSH) and geostrophic transports in the NE Pacific are examined during the 1997–1998 El Niño using altimeter data, sea level pressure (SLP) fields, proxy winds and satellite sea surface temperature (SST). Most of the signal occurs along the boundaries of the basin from Panama to the Alaska Peninsula. Changes in the SSH and alongshore transports along the boundaries are caused both by propagation of signals from the south (stronger between the equator and the Gulf of California) and by local and basin-scale winds (stronger between the Pacific Northwest and the Alaska Peninsula). Two periods of high SSH occur at the equator, May–July 1997 and October 1997–January 1998. The first coastal SSH signal moved quickly polewards to approximately 24°N in early June, then stalled and moved farther north during transient events in July–September. Large-scale wind forcing combined with the equatorial signals during the second period of high equatorial SSH (Fall 1997) to move the high SSH and poleward transports quickly around the Alaska Gyre. A connection between the boundary currents and the interior North Pacific developed as part of the large-scale response to the basin-scale winds, after changes in the boundaries. Decreases in anomalies of SSH and poleward transports began in January 1998 south of 40°N and in February 1998 farther north.     

北极和南极表面温度对中低纬度海洋热强迫的响应

利用耦合了平板海洋模型的全球气候模式进行了大量的格林函数实验,以探究两极地区对于施加在中低纬度海域的热强迫的气候响应。结果表明,北极地区的气候不仅受到距离较近的北太平洋与北大西洋的影响,远离北极的热带太平洋以及南太平洋也对其气候有显著的影响,南极地区的气候则主要是受到邻近的南大洋的影响。通过经验正交函数法的进一步分析发现,北极响应最显著的区域包括波弗特海(Beaufort Sea)、拉普捷夫海(Laptev Sea)以及北极中心区附近;南极地区的响应主要集中在别林斯高晋海(Bellinsgauzen Sea)区域。另外,利用温度归因法对辐射反馈过程和大气能量输运分解发现,北极地区表面温度的响应主要是受到了反照率反馈以及垂直递减率反馈的影响,而南极地区的响应则主要是反照率反馈发挥了作用。     

Numerical simulation of influence of the anomalies of the Central-eastern Equatorial Pacific SST and Arctic seaice cover in summer on the atmospheric circulation

A series of numerical experiments have been conducted with a perpetual July, nine-level general circulation spectral model to determine the effect of variation of the Arctic sea ice cover extent and the joint effect of anomalies of both the Arctic sea ice cover and the Central-eastern Equatorial Pacific sea surface temperature on the summer general circulation. Results show that the two factors,anomalously large extent of the Arctic sea ice cover and anomalously warm sea surface temperature over the Central-eastern Equatorial Pacific Ocean, play substantially the equal role in the effect on the summer general circulation, and either of them can notably induce the atmospheric anomalies. The main dynamical processes determining the effect of the Arctic sea ice and the equatorial SST anomalies are associated with two leading teleconnection patterns, i. e. the Asia North/American and Eurasian patterns observed in atmosphere. The results presented in this paper again prove that the general circulation is fun     

Equatorward Spreading of a Passive Tracer with Application to North Pacific Interdecadal Temperature Variations

A simulation is conducted with a realistic ocean general circulation model to investigate the three dimensional spreading of a passive tracer prescribed at the sea surface with the same distribution as the interdecadal sea surface temperature (SST) anomalies observed in the North Pacific. The tracers reaching the equator have the same sign as the major oval-shaped SST anomaly pattern in the central North Pacific but with a magnitude reduced less than 10% of the mid-latitude SST anomaly. The mixing both with the water containing SST anomalies of an opposite sign off the west coast of North America, and with the Southern Hemisphere thermocline water both contribute to the reduced equatorial amplitude. On the way to the equator in the southwestern part of the subtropical gyre, the subducted water is replenished by tracers leaking from the recirculation region to the north. The simulated passive tracer field in the subsurface layers agrees with the observed interdecadal temperature anomalies, suggesting the relevance of the processes studied here to the thermocline variability in the real North Pacific.     

北太平洋海温异常与黑龙江省夏季低温的联系及其长期预报

黑龙江省是我国最北的省份,农业生产受夏季气温高低的影响很大.六十年代后期到七十年代,平均三、四年就有一次夏季低温冷害,严重的低温冷害,可给农业生产带来大幅度减广.分析表明,北太平洋海温的变化,通过海气关系可直接影响黑龙江省的气温.研究北太平洋海温的异常变化,可能是提高黑龙江省低温冷害长期预报有希望的途径之一.     

Interannual SST variability in the Japan/East Sea and relationship with environmental variables

Interannual variability of the Japan/East Sea (JES) sea surface temperature (SST) is investigated from the reconstructed NOAA/AVHRR Oceans Pathfinder best SST data (1985–2002) using the complex empirical function (CEOF) analysis. The iterative empirical function analysis is used for the SST data reconstruction. The first two leading CEOFs account for 86.0% of total variance with 66.4% for the first mode and 19.6% for the second mode. The first CEOF mode represents a standing oscillation and a maximum belt in the central JES. There are two near-7-year events and one 2–3-year event during the period of 1985–2002. The first mode oscillates by adjacent atmospheric systems such as the Aleutian Low, the North Pacific High, the Siberian High, and the East Asian jet stream. Positive correlation in a zonal belt between the first mode JES SST anomaly and the background surface air temperature/SST anomaly reveals intensive ocean-atmosphere interaction near the Polar Front in the North Pacific. The second CEOF mode represents two features: standing oscillation and propagating signal. The standing oscillation occurs in the northern (north of 44°N) and southern (south of 39°N and west of 136°E) JES with around 180° phase difference. A weak southwestward propagating signal is detected between the two regions. The eastward propagating signal is detected from the East Korean Bay to near 135°E. The second mode contains 4–5-year periodicity before 1998 and 2–3-year periodicity thereafter. It is associated with the Arctic Oscillation, which leads it by 1–5-year. Furthermore, a strong correlation with the background surface air temperature/SST anomaly is detected in the tropical to subtropical western Pacific.     

Internnual variations of water temperature and salinity along the 137°E meridian

Analyses were performed on hydrographic data gathered along the 137°E meridian by the R/V Ryofu Maru of the Japan Meteorological Agency (JMA). Distributions were obtained of the mean and standard deviation of water temperature and salinity along the section. Relationships between interannual variations of these variables and wind forcing were examined. A correlation analysis revealed that temperature change, which occurred in the equatorial region of the western North Pacific accompanied by El Nino and La Nina events, reached about 20°N with the inclination of isotherms across the north equatorial current fluctuating around 20°N. Empirical orthogonal function (EOF) analysis of the winter water temperatures in the section was performed to extract variations following El Nino and La Nina events as the first mode and those corresponding to decadal changes of sea surface temperature (SST) in the North Pacific as the second mode. Interannual variations in the area of the North Pacific tropical saline water (NPTSW) and the North Pacific intermediate water (NPIW) along the section correspond well to interannual variations of the wind-stress curl minimum (negative value) in the area southeast of Japan. A remaining problem is to quantitatively evaluate the lag times of the variations to the wind-stress curl variation. In the equatorial region of the section, the northward extension of saline water is weak, and negative water temperature anomalies have often occurred in connection with El Nino events since the latter half of the 1970s. These changes may be part of the decadal variation of the North Pacific.     

东南沿海前汛期与后汛期降水的比较分析

本文通过对东南沿海前汛期降水与后汛期降水的多年气候变化及500hPa环流场和北太平洋海温场对比分析发现:前汛期降水与后汛期降水在年代际变化上差异明显。前汛期降水逐年变化幅度小,大旱、大涝年少;后汛期降水逐年变化幅度大,大旱、大涝年多。前汛期降水与后汛期降水的大旱、大涝年环流形势场和海温场均存在明显差异。在与北半球500hPa高度场和北太平洋海温场的相关分布上,表现出基本相反的分布类型。计算分析还发现,前期8～9月和冬季1～2月北半球副高,尤其是太平洋副高与前汛期降水相关尚好。前期1月赤道洋流区中部海域的海温,对前汛期降水均有较好的预测指示意义。前期2月北大西洋涛动和黑潮区以东至太平洋中部海域的海温对后汛期降水具有较好的预测指示意义。     

Depth Distribution of the Subtropical Gyre in the North Pacific

Large-scale aspects of the North Pacific subtropical gyre have been investigated using a climatology of temperature and salinity (World Ocean Atlas 1998). In the central and eastern parts of the basin, the axis of the subtropical gyre, defined as the meridional maximum of dynamic height, tends to move poleward from about 25°N near the surface to about 40°N in the upper intermediate layers. In the western part of the basin, the axis is seen at about 30°N, remaining almost unchanged with depth. Striking features associated with this vertical distribution include a northward shift of the bifurcation latitude of the North Equatorial Current at increasing depth and a barotropic nature of the confluence point between the Kuroshio and Oyashio at their respective western boundaries. The former occurs at about 14°N near the surface and extends north of 20°N at depths around 800 m. The latter, situated at about 36.4°N off Japan, does not appear to have a strong signature of depth-dependence. While some of these results are already known from sporadic hydrographic observations, they have not hitherto been represented in a three-dimensional climatology. This revised version was published online in July 2006 with corrections to the Cover Date.