| Title | Observations of counter-propagating Alfvenic and compressive fluctuations in the chromosphere |
| Authors | Liu, Zi-Xu He, Jian-Sen Yan, Li-Mei |
| Affiliation | Peking Univ, Sch Earth & Space Sci, Beijing 100871, Peoples R China. |
| Keywords | Sun: chromosphere turbulence solar wind SCALE MAGNETIC RECONNECTION SOLAR-WIND MODEL LOW-FREQUENCY ACTIVE-REGION WAVES SPICULES CORONA ATMOSPHERE TURBULENCE ENERGY |
| Issue Date | 2014 |
| Publisher | 中国天文和天体物理学报英文版 |
| Citation | RESEARCH IN ASTRONOMY AND ASTROPHYSICS.2014,14,(3),299-310. |
| Abstract | Recent observations have found that chromospheric spicules behave like Alfvenic fluctuations. Low-frequency Alfven waves are predicted to partially reflect in the transition region that has a gradient in the Alfven speed, thereby producing inward Alfven waves, which may interact nonlinearly with outward Alfven waves to generate Alfvenic turbulence. However, the signature of Alfvenic turbulence in the chromosphere has not yet been quantitatively analyzed with observations. Here we analyze some characteristics related to Alfvenic turbulence with the observations from Hinode/SOT. We decompose the height-time diagram of the transverse oscillations to separate the outward and inward propagating Alfvenic-like signals. The counter-propagating waves are found to have similar amplitude, period and phase speed, suggesting a state having an approximate balance in bi-directional energy fluxes. Counter-propagation of intensity oscillation with lower propagation speed is also presented, probably indicating the presence of slow mode waves. Moreover, we attempt to estimate the Elsasser spectra of the chromospheric turbulence for the first time. The relative fluctuations in the magnetic field may be measured as the local slope of wave-like shapes in spicules. The resulting low-frequency Elsasser power spectra look similar to each other without showing a dominant population, which confirms these counter-propagating low-frequency Alfvenic waves are in a state of balanced flux. These observational results are believed to help us better understand the nature of chromospheric turbulence as well as chromospheric heating. |
| URI | http://hdl.handle.net/20.500.11897/155528 |
| ISSN | 1674-4527 |
| DOI | 10.1088/1674-4527/14/3/004 |
| Indexed | SCI(E) 中国科技核心期刊(ISTIC) 中国科学引文数据库(CSCD) |
| Appears in Collections: | 地球与空间科学学院 |
