The Second Decadal Leading Mode of East Asian Summer Monsoon Rainfall          下载免费PDF全文

BAO Qing  YU Pei 《大气和海洋科学快报》2014,(5):417-421

The first decadal leading mode of East Asian summer rainfall （EASR） is characterized by rainfall anomalies along the East Asian subtropical rain belt. This study focuses on the second decadal leading mode （2DLM）, accounting for 17.3% of rainfall decadal vari- ance, as distinct from the other two neighboring modes of EAMR, based on the state-of-the-art in-situ rainfall data. This mode is characterized by a South-China-wet-Huaihe- River-dry pattern, and is dominated by a quasi-30-yr pe- riod. Further analysis reveals the 2DLM corresponds to an enhanced lower-level monsoon jet, an eastward extension of the western North Pacific subtropical high, and a weakened East Asian upper-level westerly jet flow. The Tibetan Plateau surface temperature and Pacific Decadal Oscillation （PDO） are closely linked with the 2DLM. The regressed SST pattern indicates the PDO-like pattern of sea surface temperature anomalies may have a telecon- nection relationship with the 2DLM of EASR.  相似文献   

The Relationship between the El Nin o/La Nin a Cycle and the Transition Chains of Four Atmospheric OscillationsPart I: The Four Oscillations简     

PENG Jingbei  CHEN Lieting  ZHANG Qingyun 《大气科学进展》2014,31(2):468-479

The first leading modes of the interannual variations in low-level circulation over the North and South Pacific are the Northern Oscillation （NO） and Southern Oscillation （SO）,which are oscillations in sea level pressure anomalies （SLPAs）between the eastern and western Pacific Ocean.The second leading modes are the North Pacific Oscillation （NPO） and the Antarctic Oscillation （AAO）,which reflect oscillations between the subtropics and the high and middle latitudes.The transition chains of these four oscillations were investigated using the National Centers for Environmental Prediction-National Center for Atmospheric Research （NCEP-NCAR） reanalysis data.The general pattern of the transition chain between the NO and NPO was from the negative phase of the NO （NO-） to the positive phase of the NPO （NPO＋）,then from NO＋ to NPO-to NO-.The whole transition chain took about 4-6 years.The general pattern and period of the transition between the SO and AAO were similar to those between the NO and NPO.In addition,the transition chains between the NO and NPO,and the SO and AAO,were almost simultaneous.The transition chains of the four oscillations were found to be closely connected,with the eastward propagations of SLPAs occurring along both sides of the Equator.  相似文献   

The 30–60-day Intraseasonal Oscillations over the Subtropical Western North Pacific during the Summer of 1998简     

LU Riyu  DONG Huilin  SU Qin  Hui DING 《大气科学进展》2014,31(1):1-7

The features of 30-60-day convection oscillations over the subtropical western North Pacific （WNP） were investigated, along with the degree of tropical-subtropical linkage between the oscillations over the WNP during summer 1998. It was found that 30-60-day oscillations were extremely strong in that summer over both the subtropical and tro]~ical WNP, providing a unique opportunity to study the behavior of subtropical oscillations and their relationship to tropical oscillations. Further analyses indicated that 30-60-day oscillations propagate westwards over the subtropical WNP and reach eastern China. In addition, 30-60-day oscillations in the subtropics are affected by those over the South China Sea （SCS） and tropical WNP through two mechanisms： （1） direct propagation from the tropics into the subtropics; and （2） a seesaw pattern between the tropics and subtropics, with the latter being predominant.  相似文献   

Intraseasonal Oscillation of the South China Sea Summer Monsoon and Its Influence on Regionally Persistent Heavy Rain over Southern China          下载免费PDF全文

CHEN Guanjun  WEI Fengying  ZHOU Xiuji 《Acta Meteorologica Sinica》2014,28(2):213-229

The intraseasonal oscillation（ISO） in the South China Sea summer monsoon（SCSSM） and its influence on regionally persistent heavy rain（RPHR） over southern China are examined by using satelhte outgoing long wave radiation,NCEP/NCAR reanalysis,and gridded rainfall station data in China from 1981 to 2010.The most important feature of the ISO in SCSSM,contributing to the modulation of RPHR,is found to be the fluctuation in the western Pacific subtropical high（WPSH）,along with a close link to the Madden-Julian oscillation（MJO）.Southern China is divided into three regions by using rotated empirical orthogonal functions（REOFs）for intraseasonal rainfall,where the incidence rate of RPHR is closely linked to the intraseasonal variation in rainfall.It is found that SCSSM ISOs are the key systems controlling the intraseasonal variability in rainfall and can be described by the leading pair of empirical orthogonal functions（EOFs） for the 850-hPa zonal wind over the SCS and southern China.Composite analyses based on the principal components（PCs） of the EOFs indicate that the ISO process in SCSSM exhibits as the east-west oscillation of the WPSH,which is coupled with the northward-propagating MJO,creating alternating dry and wet phases over southern China with a period of 40 days.The wet phases provide stable and lasting circulation conditions that promote RPHR.However,differences in the ISO structures can be found when RPHR occurs in regions where the WPSH assumes different meridional positions.Further examination of the meridional-phase structure suggests an important role of northward-propagating ISO and regional air-sea interaction in the ISO process in SCSSM.  相似文献   

Chinese Contribution to CMIP5：An Overview of Five Chinese Models’Performances   总被引：4，自引：0，他引：4       下载免费PDF全文

ZHOU Tianjun  CHEN Xiaolong  DONG Lu  WU Bo  MAN Wenmin  ZHANG Lixi  LIN Renping  YAO Junchen  SONG Fengfei  ZHAO Chongbo 《Acta Meteorologica Sinica》2014,28(4):481-509

An overview of Chinese contribution to Coupled Model Intercomparison Project-Phase 5 （CMIP5） is presented. The performances of five Chinese Climate/Earth System Models that participated in the CMIP5 pro ject are assessed in the context of climate mean states, seasonal cycle, intraseasonal oscillation, interan-nual variability, interdecadal variability, global monsoon, Asian-Australian monsoon, 20th-century historical climate simulation, climate change pro jection, and climate sensitivity. Both the strengths and weaknesses of the models are evaluated. The models generally show reasonable performances in simulating sea surface tem-perature （SST） mean state, seasonal cycle, spatial patterns of Madden-Julian oscillation （MJO） amplitude and tropical cyclone Genesis Potential Index （GPI）, global monsoon precipitation pattern, El Ni-no-Southern Oscillation （ENSO）, and Pacific Decadal Oscillation （PDO） related SST anomalies. However, the perfor-mances of the models in simulating the time periods, amplitude, and phase locking of ENSO, PDO time periods, GPI magnitude, MJO propagation, magnitude of SST seasonal cycle, northwestern Pacific mon-soon and North American monsoon domains, as well as the skill of large-scale Asian monsoon precipitation need to be improved. The model performances in simulating the time evolution and spatial pattern of the 20th-century global warming and the future change under representative concentration pathways pro jection are compared to the multimodel ensemble of CMIP5 models. The model discrepancies in terms of climate sensitivity are also discussed.  相似文献   

南海夏季风爆发的研究进展   总被引：3，自引：1，他引：2  

邵勰  黄平  黄荣辉 《地球科学进展》2014,(10)

南海夏季风的爆发预示着中国东部地区汛期降水的全面开始,是夏季短期气候预测中的关键因子。南海夏季风爆发的研究对改进我国夏季的短期气候预测水平具有重要意义。系统回顾了近几十年来关于南海夏季风在爆发特征、年际变化、外强迫以及内动力过程对爆发的影响机理等方面的国内外研究进展,特别总结了近年来关于大气季节内振荡对南海夏季风爆发影响的研究成果以及关于南海夏季风爆发的预测问题的研究现状,最后提出南海夏季风爆发在全球变化下的响应和可预报性等需要进一步关注的问题。  相似文献   

日冕中无衰减振荡的研究进展          下载免费PDF全文

高宇航  田晖  郭明哲  李波 《天文学报》2022,63(1):1-17

日冕中冕环的无衰减横向振荡(简称无衰减振荡)自2012年被发现以来,受到了广泛的关注.无衰减振荡具有在日冕中广泛存在以及振幅无明显变小的特性,使之在解释日冕加热和冕震学诊断上都具有相当的潜力.总结了日冕中无衰减振荡的研究进展,包括观测研究得到的一系列结果、提出的理论和数值模型以及基于无衰减振荡进行冕震学诊断的一些尝试,并且展望了未来可以进一步开展的研究.  相似文献   

1989年4月9日射电爆发中的准周期振荡特征     

王淑兰  李小聪 《中国天文和天体物理学报》1991,(1)

本文对1989年4月9日在2840 MHz上观测到的微波爆发进行分析,发现该爆发存在几十到几百秒的准周期振荡现象。这种现象可能与磁环的准周期现象有关,应遵从磁流体力学规律。通过简单初步分析,获得一些有意义的结果。  相似文献   

用磁场望远镜研究太阳振荡的初步结果     

张衡  曹莹 《天文研究与技术》1991,(2)

本文分析了北京天文台磁场望远镜λ5324速度场的时间序列资料,分别得到了带状模式及扇形模式的(l-v)二维功率谱。在这两种谱中,存在着五分钟振荡及周期在10分钟以上的长周期振荡。我们从长周期振荡中证认出球谐度为10相似文献   

磁场中p模/s模的转换及黑子对声波的吸收     

张衡  曹莹  孔勇进 《天文研究与技术》1997,(2)

在柱坐标下将黑子周围的环形区域（黑子除外）内的振荡分解为朝向黑子传播的（入射的）波和离开黑子传播的（出射的）波。对无黑子的环形区域内的振荡也进行了同样的分解。将黑子周围的入射波看成是被黑子磁流管磁化了的介质（介质内的磁场基本是水平的）中的波。而无黑子区的入射波看成是非磁化介质中的波。比较这两种波在固定波数下功率随频率的分布发现，在磁化介质中不同径向除ｎ的声波（ｐ模）频率系统降低，同时功率也降低，降低的功率最高达非磁化介质中波的功率的３０％。而比较在固定频率下功率随波数的分布发现，磁场中ｆ模及ｎ＝１，２，３的ｐ模的脊向高波数方向位移，功率的降低受频率调制，即声波在某些有限的频带中被吸收。这些观测表明，在磁场中ｐ模与磁声重力波（ＭＡＧ）产生了模式混合或耦合。模式混合的存在支持了模式转换作为ｐ模式被黑子吸收的机制的解释。此外，本文还分析了转换的ＭＡＧ波进入黑子磁流管（其中的磁场基本上是垂直的）后进一步被吸收，吸收的功率最高达ＭＡＧ波的２０％。在磁流管内没有进一步观测到模式的转换  相似文献