边缘耀斑中HeI 10830的加宽计算     

黎辉  尤建圻 《天文学报》2002,(1)

讨论了 ＨｅＩ １０８３０Ａ的 Ｄｏｐｐｌｅｒ和 Ｓｔａｒｋ加宽机制以及各种加宽参数的计算，并 得到以下一些结论：辐射阻尼对 ＨｅＩ １０８３０ Ａ的加宽作用与 Ｄｏｐｐｌｅｒ效应相比可以忽略； 在公认的耀斑电子密度（Ｎｅ＝３．２ ×１０１３ｃｍ－３）的情况下，所有阻尼项均不可能产生可以 觉察的加宽；直到 Ｎｅ＝１０１５ｃｍ－３，各种阻尼对线心半宽的增加都不起作用，其值最多 在１０－３的量级，因此；线心都可以看作是Ｄｏｐｐｌｅｒ加宽；当 Ｎｅ＞１０１４ ｃｍ－３时，Ｓｔａｒｋ 加宽，特别是电子碰撞的 Ｓｔａｒｋ加宽将在 ＨｅＩ １０８３０ Ａ的加宽中起主要作用；如要 Ｓｔａｒｋ 加宽谱线的线翼比纯Ｄｏｐｐｌｅｒ加宽大１－２倍，则阻尼加宽半宽与。可以相比拟；如果 用 Ｓｔａｒｋ加宽来解释 １９８９年边缘耀斑的观测轮廓，则电子密度将达１０～（１７）ｃｍ－３，与氦 原子的碰撞阻尼（γ３）造成的加宽对Ｉ１２和Ｉ３两分量明显不同，它们对Ｉ１２的影响比对Ｉ３ 的影响大近一个量级，我们的观测显示Ｉ１２和Ｉ３线翼的延伸基本一样，因而我们的观测 轮廓不可能是γ３造成的  相似文献   

红外波段太阳观测技术方法研究     

曹文达 《天文研究与技术》2002,(1)

1m红外太阳塔是我国未来重点发展的地面太阳观测设备 ,本文的所有工作均围绕着与此相关的红外波段太阳观测技术方法展开。1 .针对望远镜实验平台—云台太阳光谱仪 ,建立了光谱仪分光流量模型 ,并用多种实验手段验证了其可靠性。利用该模型计算了FeⅠ 1 .56μm红外太阳光谱的分光流量 ,分析了实验观测的可行性及改进方案。2 .针对探测器实验平台—PtSi红外焦平面阵列相机 ,建立了FeⅠ 1 .56μm光谱观测信噪比模型 ,模拟了各种噪声对观测的影响。在此基础上 ,在国内首次成功进行了FeⅠ1 .56μm红外太阳光谱的面阵观测实验。3 .在红外观测实验所处的高背景低对比度条件下 ,讨论了红外太阳光谱观测的图像处理方法 ,分析了观测中出现的干涉条纹的来源及解决办法 ,初步建立起了一整套红外太阳光谱与成像的定标方法和图像处理方法。4 .首次利用PVA材料 ,设计研制了一套FeⅠ 1 .56μm近红外Stokes参量偏振仪 ,并将该偏振仪安装在美国国立天文台McMath望远镜上进行了观测实验。针对一太阳黑子 ,通过扫描进行了二维的Stokes参量观测。同时建立了一套从Stokes参量反演磁矢量场的方法 ,并将反演的结果与怀柔太阳磁场望远镜的观测结果进行了比对。5.针对 1m红外太阳塔的太阳光谱仪系统 ,给出了垂直多波段光谱仪和红外  相似文献   

Study of Distinctive Regional Features of Surface Solar Radiation in North and East China          下载免费PDF全文

GUAN Fulai  ZHENG Youfei  CAI Ziying  YU Changwen  ZHANG Nan 《Acta Meteorologica Sinica》2011,25(4):494-505

Solar radiation is an important energy source for plants on the earth and also a major component of the global energy balance.Variations in solar radiation incident at the earth's surface profoundly affect the human and terrestrial environment,including the climate change.To provide useful information for predicting the future climate change in China,distinctive regional features in spatial and temporal variations of the surface solar radiation (SSR) and corresponding attributions (such as cloud and aerosol) are analyzed based on SSR observations and other meteorological measurements in North and East China from 1961 to 2007.Multiple models,such as the plane-parallel radiative transfer model,empirical and statistical models,and corrclation and regrcssion analysis methods are used in the study.The results are given as follows.(1) During 1961-2007,the total SSR in North China went through a process from quickly “dimming” to slowly “dimming”,while in East China,a significant transition from “dimming” to “brightening” occurred.Although there are some differences between thc two regional variation trends,long-term variations in SSR in the two regions are basically consistent with the observation worldwide.(2) Between the 1960s and 1980s,in both North and East China,aerosols played a critical rolc in the radiation dimming.However,after 1989,different variation trends of SSR occurred in North and East China,indicating that aerosols were not the dominant factor.(3) Cloud cover contributed less to the variation of SSR in North China,but was thc major attribution in East China and played a promoting role in the reversal of SSR from dimming to brightening,especially in the “remarkable brightening” period,with its contribution as high as 70％.  相似文献   

Force free fields and coronal heating part I. The formation of current sheets     

A. A. Van Ballegooijen 《地球物理与天体物理流体动力学》2013,107(3-4):181-211

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Flood forecasting with a watershed model: a new method of parameter updating     

XIAOLIU YANG  CLAUDE MICHEL 《水文科学杂志》2013,58(4):537-546

Abstract

Flood forecasting is of prime importance when it comes to reducing the possible number of lives lost to storm-induced floods. Because rainfall-runoff models are far from being perfect, hydrologists need to continuously update outputs from the rainfall-runoff model they use, in order to adapt to the actual emergency situation. This paper introduces a new updating procedure that can be combined with conceptual rainfall-runoff models for flood forecasting purposes. Conceptual models are highly nonlinear and cannot easily accommodate theoretically optimal methods such as Kalman filtering. Most methods developed so far mainly update the states of the system, i.e. the contents of the reservoirs involved in the rainfall-runoff model. The new parameter updating method proves to be superior to a standard error correction method on four watersheds whose floods can cause damage to the greater Paris area. Moreover, further developments of the approach are possible, especially along the idea of combining parameter updating with assimilation of additional data such as soil moisture data from field measurements and/or from remote sensing.  相似文献   

Structural kinematics,metamorphic P–T profiles and zircon geochronology across the Greater Himalayan Crystalline Complex in south‐central Tibet: implication for a revised channel flow     

J. M. Wang  J. J. Zhang  X. X. Wang 《Journal of Metamorphic Geology》2013,31(6):607-628

A specific question about the Himalayas is whether the orogeny grew by distributed extrusion or discrete thrusting. To place firm constraints on tectonic models for the orogeny, kinematic, thermobarometric and geochronological investigations have been undertaken across the Greater Himalayan Crystalline Complex (GHC) in the Nyalam region, south‐central Tibet. The GHC in this section is divided into the lower, upper and uppermost GHC, with kinematically top‐to‐the‐south, alternating with top‐to‐the‐north shear senses. A new thrust named the Nyalam thrust is recognized between the lower and upper GHC, with a 3 kbar pressure reversion, top‐to‐the‐south thrust sense, and was active after the exhumation of the GHC. Peak temperature reached ～749 °C in the cordierite zone, and decreased southwards to 633–667 °C in the kyanite and sillimanite‐muscovite zones, and northwards to greenschist facies at the top of the South Tibetan Detachment System (STDS). Pressure at peak temperature reached a maximum value in the kyanite zone of 9.0–12.6 kbar and decreased northwards to ～4.1 kbar in the cordierite zone. Zircon U‐Pb ages of a sillimanite migmatite and an undeformed leucogranite dyke cutting the mylonitized rocks in the STDS reveal a long‐lived partial melting of the GHC, which initiated at 39.7–34 Ma and ceased at 14.1 Ma. Synthesizing the obtained and collected results, a revised channel flow model is proposed by considering the effect of heat advection and convection by melt and magma migration. Our new model suggests that distributed processes like channel flow dominated during the growth of the Himalayan orogen, while discrete thrusting occurred in a later period as a secondary process.  相似文献   

Some statistical features of solar radio SVC in the rising branch of cycle 22     

Zhang Bai-rong  Ma Yuan 《Chinese Astronomy and Astrophysics》1991,15(4):449-452

For the rising branch of Cycle 22, 1987 January—1989 November, we plot the daily total flux S at each of the five wavelengths 2.0, 3.4, 6.0, 10.7 and 21.2 cm against the apparent sunspot area of the dominant sunspot A_y and find that, for several large active areas, the locus is located below the average regression line, and the increase in the radio flux is insignificant compared to the increase in the sunspot area.  相似文献   

To the problem of solar coronal heating     

O. G. Badalyan  V. N. Obridko 《Astronomy Letters》2007,33(3):182-191

We consider the adequacy of various solar coronal heating models. We show that the correlation between the intensity of the coronal Fe XIV 530.5 nm green line and the calculated magnetic field strength in the solar corona can be a useful tool for this purpose. We have established this correlation for coronal structures and magnetic fields of large spatial and temporal scales. The correlation found exhibits a strong dependence on both solar cycle phase and heliolatitude. The efficiency of a particular coronal heating mechanism is probably determined by the relative area occupied by low and high loops (including open structures). The direct current models based on slow field dissipation (DC) and the wave models based on Alfvén and magnetosonic wave dissipation (AC) are more efficient in the equatorial and polar zones, respectively.  相似文献   

Analysis of plasma and field conditions during some intensely geo-effective transient solar/interplanetary disturbances of solar cycle 23     

Yatendra Pal Singh  Munendra Singh  Badruddin 《Journal of Astrophysics and Astronomy》2006,27(2-3):361-366

The problem of solar wind-magnetosphere coupling is investigated for intense geomagnetic storms (Dst < -100nT) that occurred during solar cycle 23. For this purpose interplanetary plasma and field data during some intensely geo-effective transient solar/interplanetary disturbances have been analysed. A geomagnetic index that represents the intensity of planetary magnetic activity at subauroral latitude and the other that measures the ring current magnetic field, together with solar plasma and field parameters (V, B, Bz, σB, N, and T) and their various derivatives (BV,-BVz, BV², -BzV², B²V, Bz²V, NV²) have been analysed in an attempt to study mechanism and the cause of geo-effectiveness of interplanetary manifestations of transient solar events. Several functions of solar wind plasma and field parameters are tested for their ability to predict the magnitude of geomagnetic storm.  相似文献   

On the acceleration of solar-flare charged particles in a collapsing magnetic trap with an electric potential     

V. A. Kovalev  B. V. Somov 《Astronomy Letters》2002,28(7):488-493

We consider the kinetic problem of charged-particle acceleration in a magnetic trap with converging magnetic mirrors. We show that for a positive electrostatic potential of the trap plasma relative to the mirrors, the efficiency of confinement and acceleration increases for electrons and decreases for ions.  相似文献