A Multiple Flare Scenario where the Classic Long-Duration Flare Was Not the Source of a CME

A series of flares (GOES class M, M and C) and a CME were observed in close succession on 20 January 2004 in NOAA 10540. Radio observations, which took the form of types II, III and N bursts, were associated with these events. We use the combined observations from TRACE, EIT, Hα images from Kwasan, MDI magnetograms and GOES to understand the complex development of this event. Contrary to a standard interpretation, we conclude that the first two impulsive flares are part of the CME launch process while the following long-duration event flare represents simply the recovery phase. Observations show that the flare ribbons not only separate but also shift along the magnetic inversion line so that magnetic reconnection progresses stepwise to neighboring flux tubes. We conclude that “tether cutting” reconnection in the sheared arcade progressively transforms it to a twisted flux tube, which becomes unstable, leading to a CME. We interpret the third flare, a long-duration event, as a combination of the classical two-ribbon flare with the relaxation process following forced reconnection between the expanding CME structure and neighboring magnetic fields. Electronic Supplementary Material  The online version of this article () contains supplementary material, which is available to authorized users.     

基于GPS的高速公路车速全程监控方法研究

对高速公路车速进行有效监控与管理,是抑制违章超速行驶、减少高速公路交通事故的重要手段。现有的基于点速度和区间平均速度的高速公路车速监控方法,难以准确反应出车辆的实际行驶状态,实施效果有限,可靠性较差。文中提出基于GPS和地图匹配技术的高速公路车速全程监控和管理方法,建立相关算法的数学模型。经过理论分析和实例验证,车速监控与管理方法能实现高速公路车速的全程监控,极大地提高车速安全监控和管理的可靠性、准确性和有效性。     

Modulation of soil moisture–precipitation interactions over France by large scale circulation

How soil moisture affects precipitation is an important question—with far reaching consequences, from weather prediction to centennial climate change—, albeit a poorly understood one. In this paper, an analysis of soil moisture–precipitation interactions over France based on observations is presented. A first objective of this paper is to investigate how large scale circulation modulates soil moisture–precipitation interactions, thanks to a weather regime approach. A second objective is to study the influence of soil moisture not only on precipitation but also on the difference between precipitation and evapotranspiration. Indeed, to have a total positive soil moisture–precipitation feedback, the potential decrease in precipitation associated with drier soils should be larger than the decrease in evapotranspiration that drier soils may also cause. A potential limited impact of soil moisture on precipitation is found for some weather regimes, but its sign depends on large scale circulation. Indeed, antecedent dry soil conditions tend to lead to smaller precipitation for the negative phase of the North Atlantic Oscillation (NAO) regime but to larger precipitation for the Atlantic Low regime. This differential response of precipitation to soil moisture anomalies depending on large scale circulation is traced back to different responses of atmospheric stability. For all circulation regimes, dry soils tend to increase the lifted condensation level, which is unfavorable to precipitation. But for the negative phase of the NAO, low soil moisture tends to lead to an increase of atmospheric stability while it tends to lead to a decrease of stability for Atlantic Low. Even if the impact of soil moisture anomalies varies depending on large scale circulation (it is larger for Atlantic low and the positive phase of the NAO), dry soils always lead to a decrease in evapotranspiration. As the absolute effect of antecedent soil moisture on evapotranspiration is always much larger than its effects on precipitation, for all circulation regimes dry soil anomalies subsequently lead to positive precipitation minus evapotranspiration anomalies i.e. the total soil moisture feedback is found to be negative. This negative feedback is stronger for the Atlantic Low and the positive phase of the NAO regimes.     

实时操作系统集成调度的两级方案设计

实时操作系统的关键技术在于系统如何调度应用程序。由于多类型的实时任务并存于一个系统，单一的调度算法无法满足这一需要，于是提出了集成调度的两级方案。介绍了这一方案的设计思想及可行性，并根据这一方案，提出了一个设计框架的设想。     

ASTER遥感数据蚀变遥感异常提取研究

基于ETM+/TM数据提取矿化蚀变遥感异常已趋于成熟,而利用ASTER(先进星载热发射和反射辐射仪)遥感数据提取矿化蚀变遥感异常鲜有报道.本研究利用USGS波谱数据库中典型蚀变矿物反射率数据,重建其在ASTER数据中波谱曲线.研究表明,ASTER遥感数据可以提取Mg-OH、Al-OH、CO32-和Fe3+离子(基团)信息.热液矿床的蚀变围岩通常含有上述4种离子(基团),它们的波谱特征是蚀变遥感异常提取的理论依据.本研究利用改进"去干扰异常主分量门限技术流程",以河北省承德地区和太行山区为例,上述离子(基团)信息提取结果与野外实际分布相一致,表明利用ASTER遥感数据提取上述4种离子(基团)信息是可靠的.     

基于时序MODIS NDVI的黑河流域土地覆盖分类研究

归一化植被指数(NDVI)是植被生长状态及植被覆盖度的最佳指示因子,其时序数据也已成为基于生物气候特征开展大区域植被和土地覆盖分类的基本手段。基于时序NDVI数据的土地覆盖分类,即通过提取NDVI时间信号所包含的植被生物学参数,构建起一个包含植被生物学信息的分类特征空间。利用2006年重建得到的MODIS NDVI 16天合成时间序列数据,并结合1 km分辨率的DEM数据、野外实地调查资料等辅助数据,综合分析了不同土地覆盖类型对应的时序NDVI谱线及其第一、二谐波的特征阈值,建立决策树对黑河流域的土地覆盖开展分类研究。结果表明,基于时序MODIS NDVI谱线特征的决策树分类精度为78%,Kappa系数为0.74。利用1 km时序MODIS NDVI时间序列获得较为准确的黑河流域土地覆盖类型是可行的。     

联合不同类型重力测量数据确定地球重力场模型的迭代法

不同的重力测量数据包含了不同波段的地球重力场信息,因此要恢复更高精度的地球重力场模型,就必须对不同类型的重力测量数据进行联合处理.以地面重力异常Δg为例,推导了利用迭代法联合不同类型重力测量数据反演地球重力场模型的基本原理公式,并给出了其具体实现步骤,接着采用全球的重力异常Δg数据和扰动位T数据,基于迭代法对卫星重力梯度SGG数据解算的重力场模型进行了进一步的精化.结果表明,初始的卫星重力梯度SGG模型和经过全球重力异常Δg数据精化后的模型,其对应的累计大地水准面误差分别达到1.128cm和0.048cm、累计重力异常误差分别达到0.416mGal和0.018mGal的精度;在经过全球扰动位T数据进一步精化后的模型,其对应的累计大地水准面误差达到0.043cm、累计重力异常误差达到0.016mGal的精度.     

Evolution of the Kivu Rift,East Africa: interplay among tectonics,sedimentation and magmatism

The seismically and volcanically active Kivu Rift, in the western branch of the East African Rift System, is a type locale for studies of high‐elevation, humid‐climate rift basins, as well as magmatic basin development. Interpretations of offshore multi‐channel seismic (MCS) reflection data, terrestrial radar topography, lake bathymetry and seismicity data recorded on a temporary array provide new insights into the structure, stratigraphy and evolution of the Kivu rift. The Kivu rift is an asymmetric graben controlled on its west side by a ca. 110 km‐long, N‐S striking border fault. The southern basins of the lake and the upper Rusizi river basin are an accommodation zone effectively linking 1470 m‐high Lake Kivu to 770 m‐high Lake Tanganyika. MCS data in the eastern Kivu lake basin reveal a west‐dipping half graben with at least 1.5 km of sedimentary section; most of the ca. 2 km of extension in this sub‐basin is accommodated by the east‐dipping Iwawa normal fault, which bounds an intrabasinal horst. Lake Kivu experienced at least three periods of near desiccation. The two most recent of these approximately correlate to the African Megadrought and Last Glacial Maximum. There was a rapid lake level transgression of at least 400 m in the early Holocene. The line load of the Virunga volcanic chain enhances the fault‐controlled basin subsidence; simple elastic plate models suggest that the line load of the Virunga volcanic chain depresses the basin by more than 1 km, reduces flank uplift locally and broadens the depocentre. Not only do the voluminous magmatism and degassing to the lake pose a hazard to the riparian population, but our studies demonstrate that magmatism has important implications for short‐term processes such as lake levels, inflow and outlets, as well as long term modification of classic half‐graben basin morphology.