|
|||||
|
|
Temporal Evolution of the Solar-Wind Electron Core Density at Solar Minimum by Correlating SWEA Measurements from STEREO A and B |
|
| Authors: | A Opitz J-A Sauvaud A Fedorov P Wurz J G Luhmann B Lavraud C T Russell P Kellogg C Briand P Henri D M Malaspina P Louarn D W Curtis E Penou R Karrer A B Galvin D E Larson I Dandouras P Schroeder |
| Institution: | 1. Centre d’Etude Spatiale des Rayonnements (CNRS-UPS), University of Toulouse, Toulouse, France 2. Department of Space Science and Planetology, Physics Institute, University of Bern, Bern, Switzerland 3. Space Sciences Laboratory, University of California, Berkeley, USA 4. Institute of Geophysics and Planetary Physics, University of California, Los Angeles, USA 5. Department of Physics and Astronomy, University of Minnesota, Minneapolis, USA 6. LESIA, Observatoire de Paris, CNRS, Université Pierre et Marie Curie, Université Paris-Diderot, Meudon, France 7. Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA 8. Space Science Center, University of New Hampshire, Durham, USA |
| Abstract: | The twin STEREO spacecraft provide a unique tool to study the temporal evolution of the solar-wind properties in the ecliptic since their longitudinal separation increases with time. We derive the characteristic temporal variations at ～?1 AU between two different plasma parcels ejected from the same solar source by excluding the spatial variations from our datasets. As part of the onboard IMPACT instrument suite, the SWEA electron experiment provides the solar-wind electron core density at two different heliospheric vantage points. We analyze these density datasets between March and August 2007 and find typical solar minimum conditions. After adjusting for the theoretical time lag between the two spacecraft, we compare the two density datasets. We find that their correlation decreases as the time difference increases between two ejections. The correlation coefficient is about 0.80 for a time lag of a half day and 0.65 for two days. These correlation coefficients from the electron core density are somewhat lower than the ones from the proton bulk velocity obtained in an earlier study, though they are still high enough to consider the solar wind as persistent after two days. These quantitative results reflect the variability of the solar-wind properties in space and time, and they might serve as input for solar-wind models. |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ | |