Spatial transport and spectral transfer of solar wind turbulence composed of Alfvén waves and convective structures I: The theoretical model     

J. M. Schmidt  E. Marsch 《Annales Geophysicae》1995,13(5):459-474

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Non-Gaussian probability distributions of solar wind fluctuations     

E. Marsch  C. Y. Tu 《Annales Geophysicae》1994,12(12):1127-1138

The probability distributions of field differences x()=x(t+)-x(t), where the variable x(t) may denote any solar wind scalar field or vector field component at time t, have been calculated from time series of Helios data obtained in 1976 at heliocentric distances near 0.3 AU. It is found that for comparatively long time lag , ranging from a few hours to 1 day, the differences are normally distributed according to a Gaussian. For shorter time lags, of less than ten minutes, significant changes in shape are observed. The distributions are often spikier and narrower than the equivalent Gaussian distribution with the same standard deviation, and they are enhanced for large, reduced for intermediate and enhanced for very small values of x. This result is in accordance with fluid observations and numerical simulations. Hence statistical properties are dominated at small scale by large fluctuation amplitudes that are sparsely distributed, which is direct evidence for spatial intermittency of the fluctuations. This is in agreement with results from earlier analyses of the structure functions of x. The non-Gaussian features are differently developed for the various types of fluctuations. The relevance of these observations to the interpretation and understanding of the nature of solar wind magnetohydrodynamic (MHD) turbulence is pointed out, and contact is made with existing theoretical concepts of intermittency in fluid turbulence.  相似文献   

CELIAS - Charge, Element and Isotope Analysis System for SOHO   总被引：1，自引：0，他引：1  

D. Hovestadt  M. Hilchenbach  A. Bürgi  B. Klecker  P. Laeverenz  M. Scholer  H. Grünwaldt  W. I. Axford  S. Livi  E. Marsch  B. Wilken  H. P. Winterhoff  F. M. Ipavich  P. Bedini  M. A. Coplan  A. B. Galvin  G. Gloeckler  P. Bochsler  H. Balsiger  J. Fischer  J. Geiss  R. Kallenbach  P. Wurz  K. -U. Reiche  F. Gliem  D. L. Judge  H. S. Ogawa  K. C. Hsieh  E. Möbius  M. A. Lee  G. G. Managadze  M. I. Verigin  M. Neugebauer 《Solar physics》1995,162(1-2):441-481

The CELIAS experiment on SOHO is designed to measure the mass, ionic charge and energy of the low and high speed solar wind, of suprathermal ions, and of low energy flare particles. Through analysis of the elemental and isotopic abundances, the ionic charge state, and the velocity distributions of ions originating in the solar atmosphere, the investigation focuses on the plasma processes on various temporal and spatial scales in the solar chromosphere, transition zone, and corona. CELIAS includes 3 mass- and charge-discriminating sensors based on the time-of-flight technique: CTOF for the elemental, charge and velocity distribution of the solar wind, MTOF for the elemental and isotopic composition of the solar wind, and STOF for the mass, charge and energy distribution of suprathermal ions. The instrument will provide detailed in situ diagnostics of the solar wind and of accelerated particles, which will complement the optical and spectroscopic investigations of the solar atmosphere on SOHO. CELIAS also contains a Solar Extreme Ultraviolet Monitor, SEM, which continously measures the EUV flux in a wide band of 17 – 70 nm, and a narrow band around the 30.4 nm He II line.Principal-InvestigatorPrincipal-Investigator for data phase  相似文献   

FIRST RESULTS OF THE SUMER TELESCOPE AND SPECTROMETER ON SOHO – II. Imagery and Data Management     

Lemaire  P.  Wilhelm  K.  Curdt  W.  SchÜle  U.  Marsch  E.  Poland  A. I.  Jordan  S. D.  Thomas  R. J.  Hassler  D. M.  Vial  J. C.  KÜhne  M.  Huber  M. C. E.  Siegmund  O. H. W.  Gabriel  A.  Timothy  J. G.  Grewing  M. 《Solar physics》1997,170(1):105-122

SUMER – Solar Ultraviolet Measurements of Emitted Radiation – is not only an extreme ultraviolet (EUV) spectrometer capable of obtaining detailed spectra in the range from 500 to 1610 Å, but, using the telescope mechanisms, it also provides monochromatic images over the full solar disk and beyond, into the corona, with high spatial resolution. We report on some aspects of the observation programmes that have already led us to a new view of many aspects of the Sun, including quiet Sun, chromospheric and transition region network, coronal hole, polar plume, prominence and active region studies. After an introduction, where we compare the SUMER imaging capabilities to previous experiments in our wavelength range, we describe the results of tests performed in order to characterize and optimize the telescope under operational conditions. We find the spatial resolution to be 1.2 arc sec across the slit and 2 arc sec (2 detector pixels) along the slit. Resolution and sensitivity are adequate to provide details on the structure, physical properties, and evolution of several solar features which we then present. Finally some information is given on the data availability and the data management system.  相似文献   

SUMER - Solar Ultraviolet Measurements of Emitted Radiation     

K. Wilhelm  W. Curdt  E. Marsch  U. Schühle  P. Lemaire  A. Gabriel  J. -C. Vial  M. Grewing  M. C. E. Huber  S. D. Jordan  A. I. Poland  R. J. Thomas  M. Kühne  J. G. Timothy  D. M. Hassler  O. H. W. Siegmund 《Solar physics》1995,162(1-2):189-231

The instrument SUMER - Solar Ultraviolet Measurements of Emitted Radiation is designed to investigate structures and associated dynamical processes occurring in the solar atmosphere, from the chromosphere through the transition region to the inner corona, over a temperature range from 10⁴ to 2 × 10⁶ K and above. These observations will permit detailed spectroscopic diagnostics of plasma densities and temperatures in many solar features, and will support penetrating studies of underlying physical processes, including plasma flows, turbulence and wave motions, diffusion transport processes, events associated with solar magnetic activity, atmospheric heating, and solar wind acceleration in the inner corona. Specifically, SUMER will measure profiles and intensities of EUV lines; determine Doppler shifts and line broadenings with high accuracy; provide stigmatic images of the Sun in the EUV with high spatial, spectral, and temporal resolution; and obtain monochromatic maps of the full Sun and the inner corona or selected areas thereof. SUMER will be flown on the Solar and Heliospheric Observatory (SOHO), scheduled for launch in November, 1995. This paper has been written to familiarize solar physicists with SUMER and to demonstrate some command procedures for achieving certain scientific observations.  相似文献