利用微波遥感土壤水分产品监测东北地区春涝范围和程度

地表土壤水分是判断农田涝害的直接数据源，以欧洲太空局1978~2010年微波遥感土壤水分产品、2013年SMOS MIRASL3级土壤水分产品和气象站点的月降水数据为基础，结合土壤水分距平指数和土壤水分异常指数，分析2013年东北地区春涝影响范围和严重程度。结果表明：①东北地区以黑龙江省受涝面积最大，约11万km2，约占黑龙江省总面积的1／4；②比较多年的月降水数据与涝灾程度，发现冬春季节强降水是引发春涝的主要原因之一；③春涝的严重程度与高程呈现负相关关系，涝灾区域多集中在高程500m以下。

基于电化学阻抗法的油液在线监测传感器应用特性研究

大型机械装备润滑系统油况的在线监测是润滑故障诊断的关键技术之一,难点在于准确监测水分异常和润滑油老化失效临界点。根据油液老化过程缓慢且复杂、各种因素导致润滑油阻抗值变化的特性,研究基于电化学阻抗谱技术的油况传感器;通过连续在线监测不同润滑油状态下传感器的体相阻抗、界面阻抗和高频阻抗的变化趋势,发现体相阻抗、界面阻抗和高频阻抗的数据趋势可以用来判断油的状况,具体表现为润滑油状态影响传感器体相阻抗数值和界面阻抗数值,添加剂状态影响界面阻抗数值;油液使用时间越长,老化程度越高,体相阻抗值越高;污染物和分解产物影响高频阻抗数值。介绍油液状态传感器的实现原理,通过实验和工程论证油液状态传感器监测水分和润滑油老化失效临界点的可行性。结果表明,在特定应用场景下,电化学阻抗谱油液传感器能区分不同油液状态,能准确监测润滑系统水分异常和老化失效临界点,为设备润滑安全运维策略提供依据。

Low- and Mid-High Latitude Components of the East Asian Winter Monsoon and Their Reflecting Variations in Winter Climate over Eastern China

The present study defines a low-latitude component (regionally averaged winter 1000-hPa V-winds over 10 25°N, 105 135°E) and a mid-high-latitude component (regionally averaged winter 1000-hPa V-winds over 30 50°N, 110 125°E) of the East Asian winter monsoon (EAWM), which are denoted as EAWM-L and EAWM-M, respectively. The study examines the variation characteristics, reflecting variations in winter climate over eastern China, and associated atmospheric circulations corresponding to the two components. The main results are as follows: 1) the EAWM-L and EAWM-M have consistent variation in some years but opposite variations in other years; 2) the EAWM-M index mainly reflects the extensive temperature variability over eastern China, while the EAWM-L index better reflects the variation in winter precipitation over most parts of eastern China; and 3) corresponding to the variation in the EAWM-M index, anomalous winds over the mid-high latitudes of East Asia modulate the southward invasion of cold air from the high latitudes and accordingly affect temperatures over eastern China. In combination with the variation in the EAWM-L index, anomalous low-latitudinal winds regulate the water vapor transport from tropical oceans to eastern China, resulting in anomalous winter precipitation. These pronounced differences between the EAWM-L and the EAWM-M suggest that it is necessary to explore the monsoons' individual features and effects in the EAWM study.

Lithospheric Structure Model of Central Indian Ocean Basin Using Ocean Bottom Seismometer Data

The intense deformation zone in the central Indian Ocean, south of Indian continent is one of the most complex regions in terms of its structure and geodynamics. The deformation zone has been studied and debated in 1990s for its genesis. It was argued that deformation is mainly confined to sedimentary and oceanic crustal layers, while the large wave length geoidal anomalies, on which the deformation region lies, called for deeper sources. The inter connection between deeper and the shallower sources is found missing. The current study focuses on the complexities of this region by analyzing OBS （ocean bottom seismometer） data. The data acquired by five OBS systems along a 300 km long south-north profile in the CIOB （central Indian Ocean basin） have been modeled and the crustal and sub-crustal structure has been determined using 2-D tomographic inversion. Four subsurface layers are identified representing the sediment column, upper crustal layer, lower crustal layer and a sub-crustal layer （upper mantle layer）. A considerable variation in thickness as well as velocity at all interfaces from sedimentary column to upper mantle is observed which indicates that the tectonic forces have affected the entire crust and sub-crustal configuration. The sediments are characterized by higher velocities （2.1 kin/s） due to the increased confining pressure. Modeling results indicated that the velocity in upper crust is in the range of 5.7-6.2 km/s and the velocity of the lower crust varies from 7.0-7.6 km/s. The velocity of the sub-crustal layer is in the range of 7.8-8.4 km/s. This high-velocity layer is interpreted as magmatic under-plating with strong lateral variations. The base of the 7.0 km/s layer at 12-15 km depth is interpreted as the Moho.

Relationship between zonal position of the North Atlantic Oscillation and Euro-Atlantic blocking events and its possible effect on the weather over Europe

The North Atlantic Oscillation(NAO) exhibited a marked eastward shift in the mid-1970 s. Observations show that the extreme weather events in Europe have emerged frequently in the past decades. In this paper, based upon the daily NAO index, we have calculated the frequency of in-situ NAO events in winter during 1950-2011 by defining the Eastern-type NAO(ENAO) and Western-type NAO(WNAO) events according to its position at the east(west) of 10°W. Then, the composites of the blocking frequency, temperature and precipitation anomalies for different types of NAO events are performed. Results show that the frequency of Euro-Atlantic blocking events is distributed along the northwest-southeast(southwest-northeast) direction for the negative(positive) phase. Two blocking action centers in Greenland and European continent are observed during the negative phase while one blocking action center over south Europe is seen for the positive phase. The action center of blocking events tends to shift eastward as the NAO is shifted toward the European continent. Moreover, the eastern-type negative phase(ENAO) events are followed by a sharp decline of surface air temperature over Europe(especially in central, east, and south Europe), which have a wider and stronger impact on the weather over European continent than the western-type negative phase(WNAO) events do. A double- branched structure of positive precipitation anomalies is seen for the negative phase event, besides strong positive precipitation anomalies over south Europe for ENAO event. The eastern-type and western-type positive phase(ENAO+ and WNAO+) can lead to warming over Europe. A single-branched positive precipitation anomaly dominant in central and north Europe is seen for positive phase events.

Removing barometric pressure effects from groundwater level and identifying main influential constituents

Changes in barometric pressure can affect the micro-dynamic state of groundwater level.The groundwater level data carry a lot of important information of tectonic activity and earthquakes.It is very significant to eliminate the barometric pressure effects from the groundwater level data in order to recognize seismic anomalies effectively.With the analysis of the main influential constituents of barometric pressure and their changes,we can have a better understanding of the changes of the aquifer medium,which can provide useful information for earthquake prediction.Taking the May 12,2008 Wenchuan earthquake as an example,this paper deals with the influence of barometric pressure on groundwater level based on observational data from Nanxi,Qionglai and Chaohu wells.The methods of the linear regression and the deconvolution regression were employed to remove the barometric pressure from the groundwater level data.The harmonic analysis and the spectral analysis were used to recognize the main influential waves of barometric pressure effect.A comparison was conducted on the main influential waves before and after the earthquake.The results showed that the main influential waves of barometric pressure effect changed and the amplitudes of all constituents also changed.This phenomenon may result from the characteristics of the influential constituents of pressure,or from the changes of the aquifer medium,which were caused by the earthquake.