摘要
Recent observations have found that chromospheric spicules behave likeAlfvenic fluctuations. Low-frequency Alfven waves are predicted to partially reflectin the transition region that has a gradient in the Alfven speed, thereby producinginward Alfven waves, which may interact nonlinearly with outward Alfven wavesto generate Alfv6nic turbulence. However, the signature of Alfvenic turbulence in thechromosphere has not yet been quantitatively analyzed with observations. Here we an-alyze some characteristics related to Alfv6nic turbulence with the observations fromHinode/SOT. We decompose the height-time diagram of the transverse oscillationsto separate the outward and inward propagating Alfvenic-like signals. The counter-propagating waves are found to have similar amplitude, period and phase speed, sug-gesting 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 esti-mate the Elseisser spectra of the chromospheric turbulence for the first time. The rela-tive fluctuations in the magnetic field may be measured as the local slope of wave-likeshapes in spicules. The resulting low-frequency Elsaisser power spectra look similarto each other without showing a dominant population, which confirms these counter-propagating low-frequency Alfv6nic waves are in a state of balanced flux. These obser-vational results are believed to help us better understand the nature of chromosphericturbulence as well as chromospheric heating.
Recent observations have found that chromospheric spicules behave likeAlfvenic fluctuations. Low-frequency Alfven waves are predicted to partially reflectin the transition region that has a gradient in the Alfven speed, thereby producinginward Alfven waves, which may interact nonlinearly with outward Alfven wavesto generate Alfv6nic turbulence. However, the signature of Alfvenic turbulence in thechromosphere has not yet been quantitatively analyzed with observations. Here we an-alyze some characteristics related to Alfv6nic turbulence with the observations fromHinode/SOT. We decompose the height-time diagram of the transverse oscillationsto separate the outward and inward propagating Alfvenic-like signals. The counter-propagating waves are found to have similar amplitude, period and phase speed, sug-gesting 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 esti-mate the Elseisser spectra of the chromospheric turbulence for the first time. The rela-tive fluctuations in the magnetic field may be measured as the local slope of wave-likeshapes in spicules. The resulting low-frequency Elsaisser power spectra look similarto each other without showing a dominant population, which confirms these counter-propagating low-frequency Alfv6nic waves are in a state of balanced flux. These obser-vational results are believed to help us better understand the nature of chromosphericturbulence as well as chromospheric heating.
基金
Supported by the National Natural Science Foundation of China
