Why Do Temperature and Velocity Have Different Relationships in the Solar Wind and in Interplanetary Coronal Mass Ejections?     

P. Démoulin 《Solar physics》2009,257(1):169-184

In-situ observations of the solar wind (SW) show temperature increasing with the wind speed, whereas such a dependence is not observed in interplanetary coronal mass ejections (ICMEs). The aim of this paper is to understand the main origin of this correlation in the SW and its absence in ICMEs. For that purpose both the internal-energy and momentum equations are solved analytically with various approximations. The internal-energy equation does not provide a strong link between temperature and velocity, but the momentum equation does. Indeed, the observed correlation in the open magnetic-field configuration of the SW is the result of its acceleration and heating close to the Sun. In contrast, the magnetic configuration of ICMEs is closed, and moreover the momentum equation is dominated by magnetic forces. This implies no significant correlation between temperature and velocity, as observed.  相似文献   

POLAR investigation of the Sun—POLARIS     

T. Appourchaux  P. Liewer  M. Watt  D. Alexander  V. Andretta  F. Auchère  P. D’Arrigo  J. Ayon  T. Corbard  S. Fineschi  W. Finsterle  L. Floyd  G. Garbe  L. Gizon  D. Hassler  L. Harra  A. Kosovichev  J. Leibacher  M. Leipold  N. Murphy  M. Maksimovic  V. Martinez-Pillet  B. S. A. Matthews  R. Mewaldt  D. Moses  J. Newmark  S. Régnier  W. Schmutz  D. Socker  D. Spadaro  M. Stuttard  C. Trosseille  R. Ulrich  M. Velli  A. Vourlidas  C. R. Wimmer-Schweingruber  T. Zurbuchen 《Experimental Astronomy》2009,23(3):1079-1117

The POLAR Investigation of the Sun (POLARIS) mission uses a combination of a gravity assist and solar sail propulsion to place a spacecraft in a 0.48 AU circular orbit around the Sun with an inclination of 75° with respect to solar equator. This challenging orbit is made possible by the challenging development of solar sail propulsion. This first extended view of the high-latitude regions of the Sun will enable crucial observations not possible from the ecliptic viewpoint or from Solar Orbiter. While Solar Orbiter would give the first glimpse of the high latitude magnetic field and flows to probe the solar dynamo, it does not have sufficient viewing of the polar regions to achieve POLARIS’s primary objective: determining the relation between the magnetism and dynamics of the Sun’s polar regions and the solar cycle.

T. AppourchauxEmail:

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TEM中心回线中—远带响应特征   总被引：1，自引：0，他引：1  

蒋邦远 《物探与化探》2010,34(2)

近20年来,中心回线观测已进入全域时段,然而有关中—远带响应特征的文章极为少见,致使用户困惑,比如晚延时响应值大于早延时响应值(ε-上凸)、在同一测点2种仪器系统观测结果相差太大等。对此笔者做了详细分析。结果表明,中—远带响应特征基本为4种,ε-上凸只是其中之一,导致所测响应出现差别的主要原因是接收线圈延时。因此,若工作于中—远带,必须确切测定线圈延时,合理选择发射回线边长。  相似文献   

Periodic Appearance of Coronal Holes and the Related Variation of Solar Wind Parameters   总被引：1，自引：0，他引：1  

Manuela Temmer  Bojan Vršnak  Astrid M. Veronig 《Solar physics》2007,241(2):371-383

We compared the variability of coronal hole (CH) areas (determined from daily GOES/SXI images) with solar wind (daily ACE data) and geomagnetic parameters for the time span 25 January 2005 until 11 September 2005 (late declining phase of solar cycle 23). Applying wavelet spectral analysis, a clear 9-day period is found in the CH time series. The GOES/SXI image sequence suggests that this periodic variation is caused by a mutual triangular distribution of CHs ∼120° apart in longitude. From solar wind parameters a 9-day periodicity was obtained as well, simultaneously with the 9-day period in the CH area time series. These findings provide strong evidence that the 9-day period in solar wind parameters, showing up as higher harmonic of the solar rotation frequency, is caused by the “periodic” longitudinal distribution of CHs on the Sun recurring for several solar rotations. The shape of the wavelet spectrum from the Dst index matches only weakly with that from the CH areas and is more similar to the wavelet spectrum of the solar wind magnetic field magnitude. The distinct 9-day period does not show up in sunspot group areas which gives further evidence that the solar wind modulation is strongly related to CH areas but not to active region complexes. The wavelet power spectra for the whole ACE data range (∼1998 – 2006) suggest that the 9-day period is not a singular phenomenon occurring only during a specific time range close to solar minimum but is occasionally also present during the maximum and decay phase of solar cycle 23. The main periods correspond to the solar rotation (27^d) as well as to the second (13.5^d) and third (9^d) harmonic. Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users.  相似文献   

两种GPS测量规范在网平差检验的区别及POWERADJ转换程序的建立     

丁锐 《安徽地质》2001,11(4):250-256

论述了国家测绘局1992年6月颁发的“GPS测量规范”与中华人民共和国建设部1997年4月颁发的“GPS城市测量技术规程”在GPS观测网平差过程中的数据检验衡量标准上的区别；并在此基础上建立符合城市GPS测量规范的检验程序。  相似文献   

日冕物质抛射的数值研究——初态日冕和驱动机制的影响   总被引：1，自引：0，他引：1       下载免费PDF全文

郭伟平  王力隆 《地球物理学报》1993,36(3):269-276

初态日冕和驱动机制在日冕物质抛射的形成和演化过程中所起的作用是一个引起争论的问题.本文从MHD方程组出发,在不同的初态日冕中,数值模拟了日冕底部新磁通量喷发和热压力扰动两种驱动机制的日冕响应.结果表明,初态日冕和驱动机制对日冕物质抛射的形成及演化都有重要影响.  相似文献   

X形和三角形钢板阻尼器的阻尼力模型(Ⅰ)--基于双线性本构关系   总被引：3，自引：1，他引：3  

李冀龙  欧进萍 《世界地震工程》2004,20(1):10-16

利用软钢的双线性本构关系，依据经典力学原理推导建立了X形和三角形钢板阻尼器的阻尼力滞回模型。首先，导出了单调加载下钢板阻尼器的力与位移关系及其渐近曲线；其次，对于软钢材料本构关系分别考虑在理想弹塑性和双线性强化模型基础上，推导建立了钢板阻尼器的阻尼力模型；最后，将钢板阻尼器的阻尼力模型及其参数与试验结果进行了比较，验证了理论模型的有效性，并分析了误差存在的原因。  相似文献   

最小独立闭合环与附合导线的自动生成算法     

冯琰  张正禄  罗年学 《武汉大学学报(信息科学版)》1998,(3)

应用图论理论,直接根据控制网平差的基于测站的网点信息和观测值文件,提出了最小独立闭合环自动生成的逐步回代法和附合导线自动生成的组合法,并编程予以实现。最后用实例验证了算法的正确性和用之进行观测值质量检核的有效性。  相似文献   

GS-15重力仪电磁反馈检测技术          下载免费PDF全文

郭自强 《地震地质》1987,9(2):78

GS-15型重力仪是利用摆杆位移大小来量度重力相对变化的精密仪器,摆杆位移是通过电容换能进行测量。由于该仪器为开环检测系统,而且系统的末级加接0.01Hz的有源滤波器,这样就失去了大于0.01Hz的高频成分,且使潮波产生相位失真,同时还存在着电路非线性带来的测量误差,因而测量精度难以提高。为此笔者对GS-15型重力仪加装了电磁反馈装置,将开环检测改为闭环检测,利用电磁力使重力仪摆杆始终处于零电平的动态平衡状态,以电磁反馈输出大小来度量重力的变化,这样就将开环检测系统改装为平衡电桥闭环检测系统,其时间常数为2秒。 改装后,消除了电路的非线性影响,增强了系统的稳定性,记录的固体潮含有丰富的谐波,同时系统还增加了一路稳态零位输出,为地壳形变、地震预报和地球物理研究提供了波群丰富的资料  相似文献   

Effect of Stress on the Magnetic Memory of Induced Magnetic Anisotropy of Rocks and Its Mathematical Model     

Vetchfinskii  V.S.  Túnyi  I.  Vajda  P. 《Studia Geophysica et Geodaetica》2004,48(2):363-390

When re-heated to temperatures below the Curie temperature and subsequently cooled in a constant magnetic field (H _T), rock samples which contain magnetic minerals can acquire an induced magnetic anisotropy (IMA). As the result of acquiring the IMA, a constriction develops in the hysteresis loop of the magnetization of these rocks at the values of the magnetizing field close or equal to the HT. Thus the IMA is capable of retaining the information on the palaeointensity of the geomagnetic field, i.e., if IMA was created in a rock in the geomagnetic field in a past geological epoch, it preserves the information on the intensity of that field. Investigations have shown, that when IMA is created in a rock under external stress, the stress has an impact on the magnetic memory. Here we also deal with the issue of how stress affects the magnetic memory of IMA. A mathematical model for the effect of stress on magnetic memory phenomena related to induced magnetic anisotropy in rocks containing multidomain magnetite and titanomagnetite grains is proposed herewith. The effect of temperature on the magnetic memory of rocks is discussed also.  相似文献