Influence of interannual variability of Antarctic oscillation on mei-yu along the Yangtze and Huaihe River valley and its importance to prediction

Both correlation analysis and case study indicate that Antarctic oscillation (AAO) is closely related with summer rainfall in eastern China. When AAO is stronger in boreal spring, especially in May, there is more mei-yu rainfall in summer with a longer period along the Yangtze and Huaihe River valley. In contrast, there is less rainfall with a shorter period corresponding to a weaker AAO. Besides, an anomalous AAO changes the position and intensity of several circulation systems, which are important to summer rainfall along the Yangtze and Huaihe River valley. Furthermore, the Antarctic sea ice is negatively correlated with the intensity of AAO with a 6-month leading time. The result in this study provides a new method for the prediction of mei-yu.     

Antarctic oscillation: concept and applications

Based on the NCEP/NCAR reanalysis data set, empirical orthogonal function analysis and wrrelation analysis have been carried out. Antarctic osillation index (AOI) is defined as the difference between the zonal-mean monthly sea level pressure departures of 40°s and 65°s. Regional surface temperature and precipitation over the extratropical Southern Hemisphere have a close relationship with AO1.     

The northern annular mode: More zonal symmetric than the southern annular mode

Fan （2007） recently documented the zonal asymmetry of the Antarctic oscillation （AAO） in the austral winter. In this research, the zonal asymmetry of the northern annular mode, or the Arctic oscillation （AO）, in the interannual variability is studied for the boreal winter. It is shown that there is zonal asymmetry of the AO as well, similar to the case of the Antarctic oscillation （AAO）. However, the zonal asymmetry of the AO is considerably weaker than that of the AAO. This is far beyond the speculation, since the zonal asymmetry of the geography is larger in the Northern Hemisphere than the Southern Hemisphere. The Western and Eastern Hemispheres portions of the AO are correlated at 0.54 for 1959-1998, comparing with 0.23 for the case of the AAO. The authors also discussed the physical reason for this inter-hemispheric difference, and partly attributed it to the El Ni~o and Southern Oscillation （ENSO） cycle which may be represented by the SO index. It is indicated that the SO associated sea-level pressure （SLP） patterns are more zonal symmetric in the high latitudes of the Northern Hemisphere than the Southern Hemisphere.     

Relationship between the Antarctic oscillation in the western North Pacific typhoon frequency

Relationship between the Antarctic oscillation (AAO) and the western North Pacific typhoon number (WNPTN) in the interannual variability is examined in this research. The WNPTN is correlated with the AAO in June-July-August-September (JJAS) in 1949-1998 at -0.48 for the detrended time series, statistically significant at 99% level. The tropical atmospheric circulation as well as the sea surface temperature variability over the western Pacific associated with AAO has been analyzed. It follows that a positive phase of JJAS AAO corresponds to the larger magnitude of the vertical zonal wind shear, the anomalous low-lever anticyclonic circulation and anomalous high-level cyclonic circulation, and lower sea surface temperature in the major typhoon genesis region in the western North Pacific, thus providing unfavorable environment for the typhoon genesis, and vice versa.     

ENSO影响热带大气季节内振荡的年代际变化特征

为了研究厄尔尼诺和南方涛动(ENSO)现象影响热带大气季节内振荡(ISO)的年代际变化特征,利用奇异值分解(SVD)、小波分析和经验正交函数分析(EOF)等方法对热带大气ISO强度指数、赤道中东太平洋海温及热带大气环流场进行了分析。计算结果显示,20世纪70年代中期以前,ENSO对热带大气ISO的影响较弱;70年代中期以后,ENSO对热带大气ISO的影响加强。造成上述年代际变化的原因与热带大气环流的年代际变化有关,因此,ENSO对热带大气ISO的影响也存在年代际变化。     

基于实测冰芯数据的南极海冰厚度的数值模拟

根据我国第22次南极科学考察现场观测数据以及现场采集的冰芯分析数据,考虑太阳辐射、云量等因素对南极海冰厚度变化的影响,利用最小二乘法辨识气温与冰表面温度之间的关系,并以辨识结果所得到的冰表面温度作为上边界条件,依据实测情况取结冰点-1．81℃作为下边界条件,对一维热传导方程采用Crank-Nicolson格式进行离散,对南极中山站内拉湾附近海域海冰厚度变化进行了数值模拟,并与现场观测的海冰厚度数据进行了对比。     

Ultra-microbes are the minerogenetic constructors of oceanic polymetallic nodules

Polymetallic nodules (mangnese nodules) are a typical kind of manganese oncolites The distribution of smooth sur-face and knobbly manganese nodules is closely related to the geological background of the mine field. A systematic study on their inner laminae structure and features suggests that they are the products of millions of years reproduction and accumulation of the recently found Miniactinomyces chinensis and Spirisophaerospora pacijica .     

On cyclic oscillation in granular gas

In a Maxwell‘s demon experiment on a dilute granular gas made up of two species of particles placed in two closely connected containers, a cyclic oscillation similar to the chemical oscillations is recognized that the two species of particles cluster alternately in the two containers. Then the nonlinear behavior is qualitatively explained based on a flux model.     

A new type of oceanic crust and its dynamical significance

Conclusions There are two types of oceanic crust: the “Troodos type” with stratiform and thick oceanic crust, characterized by the development of sheeted dike swarms and thick cumulative rocks; and the “Shuanggou type” with thin oceanic crust composed of mafic plutonic and volcanic rocks, without sheeted dike swarms and ultramafic cumulates. The different types of oceanic crust represent the different dynamic processes under the mid-oceanic ridges, which relate with not only the spreading velocity of oceanic plate, but also the formation and volume of magmas under spread ridges. It is suggested that the spreading velocity of oceanic plate is most probably related with the rock assemblage, not the composition of oceanic crust.     

ENSO对东亚夏季风和我国夏季降水的影响研究进展

回顾了最近几年我国学者在ENSO对东亚夏季风和我国夏季降水影响方面的研究成果,通过夏季风时降水的影响分析ENSO对夏季降水的作用,结合1997-1998年的ENSO现象,对前人的理论和统计结果进行了讨论,指出除了ENSO发生的时间、区域、强度外,其增长和衰减率在这一问题的研究中也值得关注。     

The relationship between low frequency atmospheric oscillation and SST in equatorial Pacific

Based on analyzing the tropical Pacific SST and ECMWF data in the 1980s, the inverse characteristics between low frequency atmospheric oscillation (LFO), including intraseasonal oscillation and half-year oscillation and the SST anomalies in the tropical Pacific (SSTA) have been found. The positive SSTA corresponds to the weak LFO, the negative SSTA to the strong LFO. The correlation field further demonstrates this kind of negative correlation and points out that the anomalous LFO in Indonesia plays an important role in the variation of SSTA in the tropical centre-eastem Pacific.     

南极海冰总覆盖范围与面积的不确定性研究

目前,被动微波遥感数据已经成为提取极区海冰密集度的重要手段,其获取的海冰密集度产品不可避免的存在误差,这样的误差进而会引起南极海冰总覆盖范围和总覆盖面积的不确定性.利用蒙特卡洛方法对海冰密集度产品进行误差的模拟,对随机模拟影像进行统计分析,利用变异系数等指标量化随机误差带给南极海冰总覆盖范围和面积的不确定性.实验发现,当海冰密集度误差较小时,海冰覆盖范围的不确定性相比面积更大;当误差较大时,结论则相反.并且两者的不确定性都与分辨率和季节有关,分辨率越高,不确定性则越小,冬季比夏季的不确定性要小.     

Indonesian Throughflow in an eddy-permitting oceanic GCM

An eddy-permitting quasi-global oceanic GCM was driven by wind stresses from reanalysis data for the period of 1958-2001 to get the time series of the upper circulation in the Indonesian Sea. The model represents a reasonable pathway of Indonesian Throughflow (ITF) with Makassar Strait making the major passage transfer the North Pacific water southward. The simulated annual mean ITF transport is 14.5 Sv, with 13.2 Sv in the upper 700 m. Annual cycle is the dominant signal for the seasonal climatology of the upper layer transport. Both the annual mean and seasonal cycle agree well with the observation. The overall correlation between the interannual anomaly of the ITF transport and Nino 3.4 index reaches -0.65 in the simulation,which indicates that ENSO-related interannual variability in the Pacific is dominant in controlling the ITF transport. The relationship between the interannual anomalies of ITF and sea surface temperature in the Pacific, the Indian Ocean is not fixed in the simulation. In 1994, for instance, the intensive Indian Ocean sea surface temperature anomaly plays a dominant role in the formation of an impressive large transport of ITF.     

Signals of Antarctic Circum-polar Wave over the Southern Indian Ocean as recorded in an Antarctica ice core

Oxygen stable isotopic and ionic records, covering a period of 1745--1996, are recovered in DT001 ice core drilled in Princess Elizabeth Land, East Antarctica.Using empirical orthogonal function (EOF) analysis of the annually resolved glaciochemical time series, we find the first EOF (EOFI) represents sea-salt aerosols and is the proxy of sea level pressure (SLP) over a quasi-stationary low in the Southern Indian Ocean (SIO). δ^18O represents the sea surface temperature (SST) of the same ocean area. In the past two decades, four climatic waves as represented by SLP and SST proxies are found in the DT001 ice core, which in coincident with four Antarctic Circum-polar Waves (ACW) as revealed by NCEP/NCAR reanalysis. The phase difference between SST and SLP in the ice core is also coincident with that in ACW. Both ice-core record and reanalysis suggestthat there were no signals of ACW during 1958--1980, none during the overall recording period between 1745--1996, as there is no regular phase difference between SST and SLP.The ACW signal after early 1980s is probably attributable to the climate shift occurring over Antarctic Peninsula-Drake Passage region.     

基于海洋石油平台的海冰监测系统

【目的】有效监测渤海辽东湾海冰状况,指导破冰船破冰,保障冬季冰期海洋石油平台的安全生产。【方法】在辽东湾石油平台上构建海冰测量系统,利用视频测冰技术、视频冰速测量技术及气象观测多种手段,在2011—2015年度连续4年冬季冰期观测平台周边海冰形貌、范围、运动轨迹,并对监测数据进行分析,给出24h海冰预报。【结果】基于海洋石油平台的海冰监测系统对海冰冰量、冰厚、冰速、冰类型监测数据准确,通过数据分析可以对海冰实施年、月、周、24h预报,短期预报与实际情况基本相符合,其中24h预报准确率在95%以上。【结论】基于海洋石油平台的海冰监测系统是一套运行可靠的监测系统,能准确地观测海冰的运行趋势,为冬季渤海辽东湾的抗冰活动提供指导。     

分段均质杆件的纵向振动分析

对分段杆件的纵向振动问题进行了研究，求出了固有值、固有函数及固有频率，研究了分段界面两侧杆截面声阻抗对杆件振动特性的影响．     

南极冰夏季消退大气季节内振荡的数值试验

利用IAP－GCM数值模拟模拟了南极冰消退时大气响应的候平均时间序列场,经带通滤波研究了大气季节内振荡的特征,得到了大气对南极冰消退的响应是一种具有30－60天周期的低频遥响应。它在南半球高纬的传播基本上为西传,而在赤道附近有东传趋势,南半球中纬地区呈明显的东传现象。在纬向季节内振荡最大动能区位于大洋内,其扰动能量在波列路径上的传播具有很明显的一致性和系统性。     

西安降水短周期振荡现象

根据１９６１－１９８５年西安单站逐日压,温,湿及降水资料,分析得出压,温,湿及降水的变化特征和它们之间的关系,并将西安１９８７年１－１２月逐日１４时压,温,湿资料分离为气候值,低频值和高频值。