Regional seasonality in the intraseasonal oscillation over the Indo-Pacific Oceans     

《Dynamics of Atmospheres and Oceans》2019

The interlinked Eastern Indian Ocean (EIO) and Western Pacific Ocean (WPO), known as the Indo-Pacific warm pool, are highly active regions for intraseasonal oscillations (ISOs). Interestingly, distinct behaviors exist in ISO seasonality in these two basins. In the WPO, ISO intensity peaks in winter, decays rapidly starting from spring and reaches a minimum in summer. While in the EIO, ISO intensity exhibits a bimodal distribution, with a stronger peak in spring and a weaker one in autumn, followed by two troughs in summer and winter, respectively. Here, the regional ISO seasonality is understood in view of the regional differences in the background fields. For the bimodal ISO seasonality in the EIO, the increase from winter to spring is primarily due to elevated moisture content, the decrease from spring to summer is due to the decline in moisture and the meridional variation in vertical wind shear, and the increase from summer to autumn is mainly attributed to the meridional variation in vertical wind shear. In the WPO, the significant winter-summer contrast is mainly caused by change in moisture content.  相似文献   

Asymmetric effects of atmospheric circulation on the South China Sea summer monsoon onset     

《Dynamics of Atmospheres and Oceans》2019

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广西冬季降水的低频特征及其与MJO的联系     

何洁琳  陆虹  何慧  李艳兰  周秀华 《热带气象学报》2019,35(3):304-312

应用广西壮族自治区国家气象站降水,NCEP/NCAR逐日再分析资料,NOAA逐日向外长波辐射(OLR)等逐日资料,NOAA-CPC热带大气季节内振荡(MJO)指数等,使用经验正交函数分解方法分析了广西冬季降水的气候特征;用功率谱、带通滤波、相关分析和滞后线性回归等方法,以及定义MJO相关降水事件,研究了广西冬季降水异常偏多年的降水低频特征及其与MJO的联系。(1)广西冬季降水特征以全区一致型分布为主;冬季降水异常偏多年份的逐日降水具有14~26 d的低频周期。(2) MJO强对流在赤道印度洋东部发展并东传到西太平洋热带地区时,广西可出现冬季持续强降水。(3)当MJO异常对流在印度洋东部热带地区产生,中南半岛地区到华南地区上空为异常低频偏南和偏西南气流,有利于降水形成;当印度洋东部热带地区为MJO对流抑制区,华南地区上空为异常低频偏东气流控制,不利于降水产生。(4)华南地区上空大气环流的异常是由热带印度洋地区的MJO对流激发的Rossby波列造成。   相似文献   

利用宽频带倾斜仪观测资料检测日本9．0级大地震激发的地球自由振荡     

张纳莉  李细顺  成娜  姜成  温超  王锐锋  任佳  张晓刚 《东北地震研究》2011,27(3):32-36

本文利用张家口台宽频带倾斜仪的数字化观测资料,采用功率谱密度估计方法,在没有对资料进行去固体潮处理的情况下,准确获得了2011年3月11日日本9．0级大地震激发的oS2～oS35,基频球型自由振荡,并与地球初步参考模型（PREM）的理论自由振荡频率进行了对比,发现实测振荡频率与PREM预测的振荡频率基本符合。宽频带倾斜仪的数字化观测资料的确可以提取到日本地震激发的地球自由振荡。  相似文献   

青藏高原夏季风强弱变化及其对亚洲地区降水和环流的影响——2008年个例分析   总被引：4，自引：1，他引：3  

李菲  段安民 《大气科学》2011,35(4):694-706

利用2008年多种台站观测和再分析资料,通过相关分析和合成分析,详细讨论了青藏高原夏季风季节内变化及其与印度夏季风和东亚夏季风降水之间的关系.结果表明:2008年高原夏季风爆发偏早,降水偏多,季风活动有明显的季节内振荡特征、其准双周振荡特征与东亚夏季风指数和印度全区降水振荡周期相似.高原夏季风强(弱)时,印度全区及我国...  相似文献   

具有分布时滞的高阶中立型双曲偏微分方程的振动准则     

吕银平  林诗仲  丁朝刚 《南京气象学院学报》2011,(3):280-284

考虑了一类具有分布时滞的高阶中立型双曲泛函偏微分方程.利用Green公式、Jensen不等式,通过特征值的方法,获得了方程解在两类边值条件下振动的新的准则,所得结果推广和改进了若干文献中已有准则.  相似文献   

2007/2008年冬季中国南方低温雨雪天气期间大气准双周振荡作用分析   总被引：2，自引：0，他引：2  

邵勰  张祖强  陶丽 《气象与环境科学》2011,34(3):1-6

利用NCEP/NCAR逐日格点资料和中国气象局气象信息中心提供的727站逐日降水资料,从低频振荡角度对2007/2008年冬季中国南方低温雨雪期间的环流背景和气象要素场做了分析。分析结果表明,准双周振荡是2007/2008年冬季中国南方低温雨雪期间大气变化的重要模态。通过对低频振荡的传播分析得到：10～20 d低频波由...  相似文献   

Analyses of intraseasonal oscillation characteristics of flood-causing rainstorms in Xijiang River valley during the annually first raining season in the past years     

罗秋红  纪忠萍  吴乃庚  蔡洁云  孙汉明 《热带气象学报(英文版)》2011,17(2):136-146

Based on the daily precipitation data of nine stations representing the Xijiang River valley and the National Center for Environmental Prediction/National Center for Atmospheric Research (USA) reanalysis data, this study uses the wavelet analysis and band-pass filter methods to investigate the atmospheric intraseasonal oscillation characteristics of flood-causing rainstorms in the valley during the annually first raining seasons in 1968, 1994, 1998, 2002 and 2005. Results show that the daily precipitation in the valley exhibits significant quasi-biweekly (10 to 20 days) oscillations. The flood-causing rainstorms in the valley were mainly associated with the confluence of low-frequency warm and humid airflow in the lower latitudes and cold and dry airflow in the higher latitudes. The low-frequency vortexes were propagating or in control when this type of rainstorms took place over the valley, being favorable for the convergence of moisture at lower levels and thus vital to the formation of the rainstorms.  相似文献   

PDO对西北太平洋热带气旋活动与大尺度环流关系的影响   总被引：9，自引：4，他引：5  

何鹏程  江静 《气象科学》2011,31(3):266-273

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...  相似文献   

植被对季节内振荡影响的数值模拟          下载免费PDF全文

HAN Ying  XU Zhong-Feng 《大气和海洋科学快报》2011,4(1):1-6

The influences of vegetation on intraseasonal oscillation (ISO) were examined using the Community Atmosphere Model version 3 (CAM3).Two 15-year numerical experiments were completed:the first was performed with a realistic vegetation distribution (VEG run),and the second was identical to the VEG run except without land vegetation (NOVEG run).Generally speaking,CAM3 was able to reproduce the spatial distribution of the ISO,but the ISO intensity in the simulation was much weaker than that observed in nature:the ISO has a relatively much stronger signal.A comparison of the VEG run with the NOVEG run revealed that the presence of vegetation usually produces a weak ISO.The vegetation effects on ISO intensity were significant over West Africa and South Asia,especially in the summer half-year.Vegetation also plays an important role in modulating ISO propagation.The eastward propagation of the ISO in the VEG run was clearer than that in the NOVEG run over the West African and Maritime Continent regions.The northward propagation of the ISO in the VEG run was more consistent with observation than that in the NOVEG run.  相似文献