Projected Changes in Asian Summer Monsoon in RCP Scenarios of CMIP5   总被引：2，自引：0，他引：2       下载免费PDF全文

BAO Qing 《大气和海洋科学快报》2012,5(1):43-48

Responses of the Asian Summer Monsoon(ASM) in future projections have been studied based on two core future projections of phase five of the Coupled Model Intercomparison Project(CMIP5) coordinated experiments with the IAP-coupled model FGOALS_s2(the Flexible Global Ocean-Atmosphere-Land System Model).The projected changes of the ASM in climatological mean and interannual variability were respectively reported.Both the South Asian Summer Monsoon(SASM) and the East Asian Summer Monsoon(EASM) were intensified in their climatology,featuring increased monsoon precipitation and an enhanced monsoon lower-level westerly jet flow.Accordingly,the amplitude of the annual cycle of rainfall over East Asia(EA) is enhanced,thereby indicating a more abrupt monsoon onset.After the EA monsoon onset,the EASM marched farther northward in the future scenarios than in the historical runs.In the interannual variability,the leading pattern of the EASM,defined by the first multi-variable EOF analysis over EA,explains more of the total variances in the warmest future scenario,specifically,Representative Concentration Pathway(RCP8.5).Also,the correlation coefficients analysis suggests that the relationship between the EASM interannual variations and ENSO was significantly strengthened in the future projections,which may indicate improved predictability of the EASM interannual variations.  相似文献   

中波红外图像条纹处理方法     

陈强  胡勇  巩彩兰  李志乾  周颖  刘银年 《遥感学报》2012,16(1):93-104

卫星搭载的有效载荷在进行在轨对地观测过程中,受仪器本身特性和地球固有特性因素的影响,在图像上会产生多种观测失准和干扰现象。如图像旋转现象,蝴蝶结效应以及探元非均匀性条纹现象等。针对这类可以预见到的冗余和条纹,对仪器设计优化以及借助卫星星历轨道等辅助数据和成熟的图像处理算法可以对其实现有效地恢复。仪器在轨运行期间新引入的周期性或非周期性干扰,则需综合运用多种数据来源和关于干扰产生原理的先验知识,并结合图像处理手段实现图像恢复,同时保存原有辐射信息的真实性,为定量研究提供高质量可靠的数据准备。本研究针对某卫星中波红外图像干扰条纹,利用星上定标数据,并通过条纹现象分析和产生机理分析,探索了一种新的基于空域信号补偿原理的图像干扰条纹处理算法,通过大量图像数据处理实践证明,该算法对图像质量改善明显,且在动态范围和辐射信息保存方面优于传统频域滤波算法。  相似文献   

基于变换域方法抑制线性调频干扰的GPS接收机设计     

谭文群  芦莉  侯友国 《全球定位系统》2012,37(3):45-48

GPS接收机的信号通常很微弱,很容易受到有意或无意的干扰。对于线性调频干扰,在GPS接收机中很难用单一的时域或频域方法消除,因为线性调频干扰不同于一般的宽带或窄带干扰。另外线性调频干扰在变换域有不同于GPS C/A码的显著特征,基于此特点设计了一种在变换域抑制线性调频干扰的GPS接收机。分析了线性调频干扰在变换域的特征,仿真结果验证了这种设计方法的可行性。  相似文献   

山东大张矽卡岩型铁矿床中铁的富集机制 ——来自流体包裹体和氢、氧同位素的证据     

张兆年  曹毅  朱裕振  庞振山  沈立军  管继云  郭晨芳 《矿床地质》2022,41(1):91-105

大张铁矿是鲁西地区近年来新发现的一个重要的矽卡岩型矿床.矿体主要赋存于石英二长闪长岩与奥陶系马家沟组灰岩接触带及其附近.根据脉体穿插关系和交代蚀变特征,将大张矽卡岩型铁矿床成矿过程划分为矽卡岩阶段、氧化物阶段、硫化物阶段和碳酸盐阶段.通过对透辉石、绿帘石、石英和方解石等透明矿物显微观察发现,大张铁矿中流体包裹体类型主要...  相似文献   

Cloud radiative forcing in Asian monsoon region simulated by IPCC AR4 AMIP models   总被引：1，自引：0，他引：1  

李剑东  刘屹岷  吴国雄 《大气科学进展》2009,26(5):923-939

This study examines cloud radiative forcing (CRF) in the Asian monsoon region (0^o--50^oN,60^o--150^oE) simulated by Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) AMIP models. During boreal winter, no model realistically reproduces the larger long-wave cloud radiative forcing (LWCF) over the Tibet Plateau (TP) and only a couple of models reasonably capture the larger short-wave CRF (SWCF) to the east of the TP. During boreal summer, there are larger biases for central location and intensity of simulated CRF in active convective regions. The CRF biases are closely related to the rainfall biases in the models. Quantitative analysis further indicates that the correlation between simulated CRF and observations are not high, and that the biases and diversity in SWCF are larger than that in LWCF. The annual cycle of simulated CRF over East Asia (0^o--50^oN, 100^o--145^oE) is also examined. Though many models capture the basic annual cycle in tropics, strong LWCF and SWCF to the east of the TP beginning in early spring are underestimated by most models. As a whole, GFDL-CM2.1, MPI-ECHAM5, UKMO-HadGAM1, and MIROC3.2 (medres) perform well for CRF simulation in the Asian monsoon region, and the multi-model ensemble (MME) has improved results over the individual simulations. It is suggested that strengthening the physical parameterizations involved over the TP, and improving cumulus convection processes and model experiment design are crucial to CRF simulation in the Asian monsoon region.  相似文献   

Bimodality of the South Asia High simulated by coupled models     

周宁芳  俞永强  钱永甫 《大气科学进展》2009,26(6):1226-1234

The observed South Asia High (SAH) center is characterized by two distinctive equilibrium modes during boreal midsummer, namely the center of SAH is located between 82.5^o--92.5^oE for the Tibetan Plateau mode and between 55^o--65^oE for the Iranian Plateau mode, respectively. The present study describes the ability of 15 coupled general circulation models (CGCM) used in the Intergovernmental Panel on Climate Changes (IPCC) 4th Assessment Report to reproduce the observed bimodality of the SAH. These models reveal a wide range of skill in simulating this bimodality. Nearly half of the models reproduced the bimodality, while the other half of the models did not simulate well these two modes whereas usually preferring one mode. The models that reproduced the bimodality of the SAH present similar horizontal and vertical circulations as those features from the NCEP reanalysis data. The results from these models identify the warm characteristics of the SAH and indicate that these two modes have different dynamic and thermodynamic properties. Different characteristics of the simulated sensible heat and latent heat related to precipitation partly contribute to the difference in the simulations of the SAH bimodality. The majority of these models that prefer to simulate the Tibetan Plateau mode produce a small sensible heat flux difference between the Iranian Plateau and the Tibetan Plateau, and also generally simulate a very strong false precipitation center over the east of the Tibetan Plateau, which indicates strong latent release and thereby contributes to the preference of the SAH center on the Tibetan Plateau. Whereas, the models that reproduce the bimodality of the SAH tend to simulate large precipitation over the southern Himalayas and no obviously false precipitation is produced over the east of the Tibetan Plateau. In addition, the models resolution may also have important impacts on the simulations of precipitation.  相似文献   

印度洋偶极子研究进展综述   总被引：10，自引：2，他引：8  

肖莺  张祖强  何金海 《热带气象学报》2009,25(5):621-627

印度洋偶极子（IOD）是影响亚洲气候异常的重要系统之一。自1999年IOD提出以来,国内外学者对其形成机理及其与ENSO相互作用的研究取得了很大进展。综述了近年来国内外学者关于印度洋偶极子的定义、时空分布特征、形成机理、与ENSO的关系、对东亚气候的影响等问题的研究成果,提出了目前该领域存在的科学问题。  相似文献   

有限区域流函数和速度势的3种求解方法在分析台风Bilis暴雨增幅中的比较研究     

任晨平  曹洁  王黎娟  崔晓鹏 《气候与环境研究》2013,18(6):721-732

将有限区域流函数、速度势求解中常用的两种张驰法(即理查逊法和加速利布曼法)与调和—余弦谱展开法(H-C法)进行了比较,理论研究表明:H-C法单独考虑边界影响分量,物理意义明确,且不会丢失边界上的天气系统;从计算上看,H-C法重建的风场能精确还原原始风场,且计算效率明显高于两种张驰法,即收敛更快。通过在台风Bilis(0604)暴雨增幅过程诊断中的应用发现,常用的两种张驰迭代方法在求解有限区域流函数和速度势的问题上效果都不是很好,即:用理查逊法和加速利布曼法计算的流函数和速度势重建的风场与原始风场差别较大,不能准确还原原始风场;用H-C法不仅计算效率高,还原的风场与原始风场差异极小,且不受南边界较强的西南季风涌影响,在暴雨增幅前期能较好地反映与暴雨增幅相关的强辐合信号。因此,可用H-C法计算得到的无辐散风和无旋风对有限区域的天气系统进行更深入的动力结构分析。  相似文献   

Simulated Change in the Interannual Variability of South Asian Summer Monsoon in the 21st Century   总被引：1，自引：0，他引：1  

FU Yuanhai  LU Riyu 《大气科学进展》2010,27(5):992-1002

This study investigates the projected changes in interannual variability of South Asian summer monsoon and changes of ENSO-monsoon relationships in the 21st century under the Intergovernmental Panel on Climate Change (IPCC) scenarios A1B and A2, respectively, by analyzing the simulated results of twelve Coupled Model Intercomparison Project Phase 3 (CMIP3) coupled models. The dynamical monsoon index (DMI) was adopted to describe the interannual variability of South Asian summer monsoon, and the standard dev...  相似文献   

Interdecadal Variability of East Asian Summer Monsoon Precipitation over 220 Years （1777-1997）   总被引：1，自引：1，他引：0  

Chun-Ji KIM  QIAN Weihong  Hyun-Suk KANG  Dong-Kyou LEE 《大气科学进展》2010,27(2):253-264

In this study, long-term (1777–1997) precipitation data for Seoul, Korea, wetness indices from eastern China, and modern observations are used to identify the interdecadal variability in East Asian summer monsoon precipitation over the last 220 years. In the East Asian monsoon region, two long-term timescales of dry–wet transitions for the interdecadal variability and quasi-40-and quasi-60-year timescales are dominant in the 220-year precipitation data of Seoul, as well as in the wetness indices over China....  相似文献