博乐市２００５－２００９年地温变化特征

利用1955年-2003年NCEP＼NCAR再分析资料和美国Scripps海洋研究所环境数据分析中一0（JEDAC）提供的冬季热含量资料,采用小波分析、相关及合成分析等方法,分析了西太平洋暖池热含量变化特征及其与东亚冬季风关系。结果表明：西太平洋暖池热含量与东亚冬季风有着非常密切的联系,当西太平洋暖池热含量异常偏高时,对流层低层在菲律宾及以东洋面形成一个异常的气旋性环流,中国大陆上空形成一个异常的反气旋性环流,从而使得东亚冬季风在东南区加强,西北区减弱。     

西太平洋暖池对夏季华东海面日最大风速变化的影响

利用1979—2018年ERA Interim地面10 m风场、位势高度场、温度场和风场,Hadley中心HadISST再分析海温资料,采用SVD分析、合成分析等方法,研究了夏季（6—8月）西太平洋暖池关键海域海表面温度（Sea Surface Temperature,简称SST）对华东海域夏季10 m日最大风速变化的影响关系。SVD分析结果表明,夏季华东近海风速变化与菲律宾以东海域SST有明显负相关,第一模态左、右空间向量的时间系数相关达0.58,通过了置信度为95%的显著性检验。当西太平洋暖池SST正异常时,暖池海域SST增高,西北太平洋副热带高压（以下简称副高）加强,副高脊线北进（西北太平洋副高脊线纬度位置与暖池SST相关系数达到0.46,通过置信度为95%显著性检验）。此时华东近海正处于副高控制,近海下沉运动增强,大气温度垂直剖面有普遍增温现象,10 m风场有偏北风异常,海面风速减小约占40 a平均风速的约30%;当暖池SST负异常时,副高东撤南退,华东近海冷空气活动加强,温度垂直剖面存在显著降温现象,华东近海风速增加占40 a平均风速的20%以上。本研究进一步说明了暖池SST异常是一个有效的预报因子,可用于华东近海海面风速预测预报。     

西太平洋暖池海温异常与中国夏季降水的关系

利用1951—2007年NOAA延长重构的海温资料、NCEP/NCAR再分析资料和中国160站降水资料,研究了夏季西太平洋暖池海温的年际变化特征及其与中国夏季降水的关系。结果表明,夏季西太平洋暖池海温异常具有明显的年际变化特征;夏季西太平洋暖池海温异常偏高(低)时,亚洲热低压减弱(加强),西太平洋副热带高压加强(减弱)、位置偏西(偏东),850 hPa风场上中国东部地区为偏北(南)风距平,使得东亚夏季风减弱(增强),导致长江中下游地区夏季降水偏多(少)。     

Possible Origins of the Western Pacific Warm Pool Decadal Variability

In this study,the impacts of the Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Oscillation (AMO) on the western Pacific warm pool (WPWP) were investigated.Our results show that the WPWP is linked with the PDO and the AMO at multiple time scales.On the seasonal time scales,the WPWP and the PDO/AMO reinforce each other,while at decadal time scales the forcing roles of the PDO and the AMO dominate.Notably,a positive PDO tends to enlarge the WPWP at both seasonal and decadal time scales,while a positive AMO tends to reduce the WPWP at decadal time scales.Furthermore,the decadal variability of the WPWP can be well predicted based on the PDO and AMO.     

Oceanic Origin of A Recent La Nina-Like Trend in the Tropical Pacific

Global ocean temperature has been rising since the late 1970s at a speed unprecedented during the past century of recordkeeping.This accelerated warming has profound impacts not only on the marine ecosystem and oceanic carbon uptake but also on the global water cycle and climate.During this rapid warming period,the tropical Pacific displays a pronounced La Nin a-like trend,characterized by an intensification of west-east SST gradient and of atmospheric zonal overturning circulation,namely the Walker circulation.This La Nin a-like trend differs from the El Nin o-like trend in warm climate projected by most climate models,and cannot be explained by responses of the global water cycle to warm climate.The results of this study indicate that the intensification of the zonal SST gradient and the Walker circulation are associated with recent strengthening of the upper-ocean meridional overturning circulation.     

Interannual Salinity Variability in the Tropical Pacific in CMIP5 Simulations

Salinity variability and its causes in the tropical Pacific are analyzed using observations, reanalysis products and model simulations. The mixed-layer salinity(MLS) budget analyses from observations and reanalysis products indicate that its interannual evolution is closely related to ENSO and is predominantly governed by surface forcing and surface advection in the western-central equatorial Pacific. It is found that the observed MLS tendency leads Nin?o3.4 by about 12 months due to the effect of negative freshwater flux(evaporation minus precipitation). These observation-based analyses are used to evaluate the corresponding simulation using GFDL-ESM2 M. It is evident that the model can simulate the spatiotemporal variations of MLS with some discrepancies compared to observations. In the warm pool of the equatorial Pacific the MLS tendency in the model is sensitive to ocean dynamics, however model biases cause the tendency to be underestimated. In particular, the freshwater flux is overestimated while the ocean surface zonal current and vertical velocity at the base of the mixed layer are underestimated. Due to model biases in representing the related physics, the effects of surface forcing on the simulated MLS budget are overestimated and those of subsurface and surface advection are relatively weak. Due to weaker surface advection and subsurface forcing than observed, the simulated compensations for surface forcing are suppressed, and the simulated MLS tendency that leads Nin?o3.4 by 8–10 months, which is shorter than the observed lead time. These results are useful for the interpretation of observational analyses and other model simulations in the tropical Pacific.     

西太平洋暖池次表层海温异常 与ENSO循环的相互作用

利用1964～1993年的太平洋次表层海温资料,进一步分析研究了西太平洋暖池次表层海温异常与ENSO循环的关系。合成及相关分析的结果进一步表明,西太平洋暖池次表层海温的暖（冷）异常及其东传对ENSO的发生起着十分重要、且更直接的作用。然而,赤道西太平洋异常纬向风是造成次表层海温异常东传的重要原因,而纬向风的异常又是由于东亚冬季风异常活动所引起的,这间接地说明了异常东亚冬季风对西太平洋暖池次表层海温距平东传的重要作用。通过研究还发现,ENSO发生后,北半球副热带地区将有次表层暖（冷）海温距平沿着10～20oN纬带西传,这是导致西太平洋暖池次表层海温发生异常的重要原因之一。也就是说,西太平洋暖池次表层海温异常与ENSO循环之间是相互影响、相互作用的。     

The Impact of Global Warming on the Pacific Decadal Oscillation and the Possible Mechanism简

The response of the Pacific Decadal Oscillation （PDO） to global warming according to the Fast Ocean Atmosphere Model （FOAM） and global warming comparison experiments of 11 IPCC AR4 models is investigated. The results show that North Pacific ocean decadal variability, its dominant mode （i.e., PDO）, and atmospheric decadal variability, have become weaker under global warming, but with PDO shifting to a higher frequency. The SST decadal variability reduction maximum is shown to be in the subpolar North Pacific Ocean and western North Pacific （PDO center）. The atmospheric decadal variability reduction maximum is over the PDO center. It was also found that oceanic baroclinic Rossby waves play a key role in PDO dynamics, especially those in the subpolar ocean. As the frequency of ocean buoyancy increases under a warmer climate, oceanic baroclinic Rossby waves become faster, and the increase in their speed ratio in the high latitudes is much larger than in the low latitudes. The faster baroclinic Rossby waves can cause the PDO to shift to a higher frequency, and North Pacific decadal variability and PDO to become weaker.     

影响夏季西北太平洋副热带高压年际变率的关键海区及影响机制

西北太平洋副热带高压(西太副高)是影响东亚夏季气候的主要环流系统,其年际变率受热带多个海区的海-气相互作用过程的调控。为明确影响夏季西太副高的关键海区及其影响机制,在总结最近十余年来相关研究进展的基础上,归纳出影响夏季西太副高年际变率的5个关键海区,包括赤道中东太平洋、热带印度洋、副热带西北太平洋、海洋大陆附近海区以及热带大西洋。阐述了这5个关键海区的海温异常影响西太副高年际变率的机制,并探讨了5个关键海区海温异常的形成机制。围绕夏季西太副高的年际变率,回顾了当前气候模式的模拟和预测研究的现状。最后,提出了本领域亟待解决的关键科学问题,展望未来可能的研究热点。     

西北太平洋近赤道热带气旋生成的特征分析

1979—2012年西北太平洋存在70个形成于0°～5°N的低纬度地区的热带气旋(TC),占TC总量的8%,其中达到台风等级的个数占64%。而针对此类缺少一定科氏力作用而形成的罕见TC生成的研究相对较少。本文利用JTWC的TC最佳观测资料、ERA-Interim再分析资料,以及NOAA-OISST海温资料,以西北太平洋近赤道TC为研究对象,统计诊断了其年际、年代际、季节分布特征,分析了其大尺度环境背景场,重点探讨了近赤道TC生成的影响因子。研究结果表明,近赤道TC具有明显的年际与年代际变化,并且近赤道TC具有与西北太平洋总TC恰好相反的季节变化。近赤道TC生成的大尺度环境背景场是东北冬季风与其在近赤道地区偏转形成的西北风之间的气旋性环流。对流层低层的绝对涡度动力项与对流层中层的湿度热量项是近赤道TC生成的主要贡献因子,并且相对于5°～10°N生成的TC,近赤道TC对对流层低层的正涡度与对流层中层的湿度条件的要求更高。     

Decadal Indian Ocean Dipolar Variability and Its Relationship with the Tropical Pacific

A robust decadal Indian Ocean dipolar variability(DIOD) is identified in observations and found to be related to tropical Pacific decadal variability(TPDV).A Pacific Ocean–global atmosphere(POGA) experiment,with fixed radiative forcing,is conducted to evaluate the DIOD variability and its relationship with the TPDV.In this experiment,the sea surface temperature anomalies are restored to observations over the tropical Pacific,but left as interactive with the atmosphere elsewhere.The TPDV-forced DIOD,represented as the ensemble mean of 10 simulations in POGA,accounts for one third of the total variance.The forced DIOD is triggered by anomalous Walker circulation in response to the TPDV and develops following Bjerknes feedback.Thermocline anomalies do not exhibit a propagating signal,indicating an absence of oceanic planetary wave adjustment in the subtropical Indian Ocean.The DIOD–TPDV correlation differs among the 10 simulations,with a low correlation corresponding to a strong internal DIOD independent of the TPDV.The variance of this internal DIOD depends on the background state in the Indian Ocean,modulated by the thermocline depth off Sumatra/Java.     

Intraseasonal oscillation intensity over the western North Pacific:Projected changes under global warming

本文利用8个CMIP5模式的日资料,预估了RCP4.5和RCP8.5情景下全球增温达1.5℃和2.0℃时西北太平洋夏季30～60天和10～20天季节内振荡(ISO)强度的变化情况.大多数模式都认为,无论增温水平或情景如何,预估结果均显示从中南半岛南部到菲律宾以东的带状区域内ISO强度增加,并且关键气象要素背景的变化会对...     

热带气旋潜在生成指数的对比分析及其在西北太平洋的改进

本研究评估了现有热带气旋(Tropical Cyclone,TC)潜在生成指数(Genesis Potential Indice,GPI)对北大西洋和西北太平洋热带气旋生成频数(TC Genesis Frequency,TCGF)时空特征的表征能力。结果表明,现阶段使用的GPIs能较好地再现两个海盆TCGF的空间分布和季节循环特征,以及北大西洋TCGF的年际变化,但几乎不能模拟西太平洋TCGF年际时间尺度上的变化。利用美国联合飓风警报中心(Joint Typhoon Warming Center,JTWC)提供的1979—2017年热带气旋最佳路径数据集和ERA-Interim再分析数据,对西北太平洋GPI进行了改进。考虑到相对涡度在西北太平洋对热带气旋生成的重要作用,将绝对涡度分离为相对涡度和地转涡度(f),移除相对湿度,使用多元线性回归的方法构建了GPI_WNP。与现有GPIs相比,改进后的GPI_WNP不仅对西北太平洋TCGF的空间分布和季节循环有较好的模拟能力,并且可以再现其年际变化特征。     

西太平洋暖池对西北太平洋季风槽和台风活动影响过程及其机理的最近研究进展

本文回顾和综述了近年来关于西太平洋暖池对西北太平洋热带气旋和台风（TCs）活动影响过程及其机理的研究进展。文中首先简单回顾了近年来关于西太平洋暖池热状态和菲律宾周围对流活动变化特征及其对与TCs活动有关的南海夏季风爆发和西太平洋副热带高压的季节内、年际变异的影响过程和机理的研究;然后,本文系统地回顾了近年来关于西太平洋暖池热状态通过西北太平洋季风槽影响TCs活动年际和年代际变化的影响过程及其机理的研究。此外,文中还指出了关于西太平洋暖池对西北太平洋上空季风槽和TCs活动变异的热力和动力作用需进一步深入研究的科学问题。     

PDO对西北太平洋热带气旋活动与大尺度环流关系的影响

利用NCEP再分析资料和上海台风研究所整编的热带气旋资料,研究了在太平洋年代际振荡(PDO)冷暖位相中西北太平洋热带气旋频数与太平洋海表温度(SST)年际相关的分布差异,以及500 hPa高度场对热带气旋频数和生成源地的影响.结果表明,在PDO冷位相时期,热带气旋频数与赤道东太平洋SST存在显著相关,副热带高压位置偏东...     

PDO对西太平洋副热带高压年代际东退的可能贡献

以往的研究已证实,西太平洋副热带高压(副高)在1970s后期减弱东退.基于大气模式(CAM4)的理想型海温强迫试验,结果表明:副高的东退可能是大气对于正位相太平洋年代际振荡(PDO)的相应.伴随着PDO转变为正位相,西太平洋至印度半岛以及热带东太平洋的对流加热增强,大气表现为Gill型响应,在亚洲大陆至西太平洋上空低层产生气旋性异常,有利于副高东退.同时,高层产生反气旋异常,使得东亚西风急流加强和向南扩展,进而调节西太平洋上空的次级环流,进一步有利于副高东退.     

020106 西太平洋暖池区海表水温暖异常对东亚夏季风影响的研究

对夏季热带西太平洋暖池区海表水温暖异常年的东亚大气环流做了合成分析,然后用奇异值分解(SVD)方法做了进一步统计检验,揭示了东亚夏季风变异与暖池区海表水温异常的密切关系和它们间最佳耦合模态.结果发现当夏季暖池区暖异常时,在对流层低层西太平洋地区可产生一个强的反气旋偏差环流,使得副热带高压南侧东风气流大大加强,并向西伸展到中南半岛南部,从而影响了东南亚热带和副热带地区西南季风的变化(强/弱).中南半岛至中国东部大陆夏季风增强,赤道东印度洋、南海南部和中部、西太平洋热带地区夏季风减弱.SVD分析还发现经向风和纬向风与海表水温之间各存在两个最佳耦合模态,结果表明,不仅整个暖池海表水温暖/冷异常对东亚大气环流异常有重要影响,而且暖池区内海表水温有显著的暖和冷异常差异时,对东亚大气环流的影响也很明显(耦合总体平方协方差约占总体协方差的0.20),尤其是在南海至长江以南地区.     

Impact of the thermal state of the tropical western Pacific on onset date and process of the South China Sea summer monsoon

Since the early or late onset of the South China Sea summer monsoon （SCSM） has a large impact on summer monsoon rainfall in East Asia, the mechanism and process of early or late onset of the SCSM are an worthy issue to study. In this paper, the results analyzed by using the observed data show that the onset date and process of the SCSM are closely associated with the thermal state of the tropical western Pacific in spring. When the tropical western Pacific is in a warming state in spring, the western Pacific subtropical high shifts eastward, and twin cyclones are early caused over the Bay of Bengal and Sumatra before the SCSM onset. In this case, the cyclonic circulation located over the Bay of Bengal can be early intensified and become into a strong trough. Thus, the westerly flow and convective activity can be intensified over Sumatra, the Indo-China Peninsula and the South China Sea （SCS） in mid-May. This leads to early onset of the SCSM. In contrast, when the tropical western Pacific is in a cooling state, the western Pacific subtropical high anomalously shifts westward, the twin cyclones located over the equatorial eastern Indian Ocean and Sumatra are weakened, and the twin anomaly anticyclones appear over these regions from late April to mid-May. Thus, the westerly flow and convective activity cannot be early intensified over the Indo-China Peninsula and the SCS. Only when the western Pacific subtropical high moves eastward, the weak trough located over the Bay of Bengal can be intensified and become into a strong trough, the strong southwesterly wind and convective activity can be intensified over the Indo-China Peninsula and the SCS in late May. Thus, this leads to late onset of the SCSM. Moreover, in this paper, the influencing mechanism of the thermal state of the tropical western Pacific on the SCSM onset is discussed further from the Walker circulation anomalies in the different thermal states of the tropical western Pacific.     

Establishment of an Objective Standard for the Definition of Binary Tropical Cyclones in the Western North Pacific

To develop an objective standard for defining binary tropical cyclones(BTCs) in the western North Pacific(WNP),two best-track datasets, from the China Meteorological Administration and the Joint Typhoon Warning Center, were adopted for statistical analyses on two important characteristics of BTCs—two TCs approaching each other, and counterclockwise spinning. Based on the high consistency between the two datasets, we established an objective standard,which includes a main standard for defining BT...     

澳大利亚冷空气活动对西北太平洋热带气旋生成的影响

利用1980—2012年NCEP/NCAR再分析资料及中国气象局的最佳台风路径资料,研究澳大利亚冷空气活动对西北太平洋热带气旋生成的影响。研究发现,北半球夏季925 h Pa经向风超过6 m/s的频数在澳大利亚东北部海域最高,达40 d/a。为此,确定澳大利亚冷空气侵入南北半球低纬的关键区为澳大利亚东北部所罗门海地区,并用该区域经向风风速定义了一个澳大利亚冷空气活动强度指数。该指数与越赤道气流及赤道西风都有很好的相关关系,还与同期的SOI(Southern Oscillation Index,南方涛动指数)显著相关。当SOI偏低(高)时,关键区经向风风速偏强(弱)。合成分析和相关分析结果表明,澳大利亚冷空气活动强、弱年西北太平洋热带气旋生成的位置的变化与季风槽的变化一致,西北太平洋热带气旋生成总数则无显著差异。澳大利亚冷空气活动强年季风槽偏强偏东,热带气旋生成位置偏东偏南;而弱年季风槽偏弱偏西,热带气旋生成位置偏西偏北。低层涡度场、水汽输送、风垂直切变以及低纬地区对流活动的分布表明,澳大利亚冷空气活动强年有利于热带气旋生成位置偏东、偏南;弱年偏西、偏北。