||Turbulent Fluctuations in G-band and K-line Intensities Observed with
the Rapid Oscillations in the Solar Atmosphere (ROSA) Instrument
||463, 2nd ATST-EAST Workshop in Solar Physics: Magnetic Fields from the Photosphere to the Corona
||Cadavid, A. C.; Lawrence, J. K.; Christian, D. J.; Jess, D. B.; Mathioudakis, M.
||Using the Rapid Oscillation in the Solar Atmosphere (ROSA) instrument at the Dunn Solar Telescope
we have found that the spectra of fluctuations of the G-band (cadence 1.05 s) and Ca II K-line
(cadence 4.2 s) intensities show correlated fluctuations above white noise out to frequencies
beyond 300 mHz and up to 70 mHz, respectively. The noise-corrected G-band spectrum presents a
scaling range (Ultra High Frequency “UHF”) for f = 25–100 mHz, with an exponent
consistent with the presence of turbulent motions. The UHF power, is concentrated at the
locations of magnetic bright points in the intergranular lanes, it is
highly intermittent in time and characterized by a positive kurtosis κ. Combining
values of G-band and K-line intensities, the UHF power, and κ, reveals two distinct “states”
of the internetwork solar atmosphere. State 1, with κ ≈ 6, which includes almost all
the data, is characterized by low intensities and low UHF power. State 2, with κ ≈ 3,
including a very small fraction of the data, is characterized by high intensities and high UHF power.
Superposed epoch analysis shows that for State 1, the K-line intensity presents 3.5 min
chromospheric oscillations with maxima occurring 21 s after G-band intensity maxima implying a
150–210 km effective height difference. For State 2, the G-band and K-line intensity maxima
are simultaneous, suggesting that in the highly magnetized environment sites of G-band
and K-line emission may be spatially close together.
Analysis of observations obtained with Hinode/SOT
confirm a scaling range in the G-band spectrum up to 53 mHz also consistent with turbulent
motions as well as the identification of two distinct states in terms of the H-line
intensity and G-band power as functions of G-band intensity.