Dynamic solar atmosphere revealed via Doppler velocity measurements of multispectral lines during the 2013 total solar eclipse

ABSTRACT Total solar eclipses provide a special opportunity to reveal a dynamic solar atmosphere extending from photosphere to inner corona. We analysed the spectroscopic observations obtained during the 2013 total solar eclipse using a fibre-based spectrometer in the wavelength range 5162–5325 Å. We investigated the complex Doppler velocities exhibited in the sky, flash, and coronal spectra. The field-of-view adjacent to the solar east limb ($\sim 0.04\ \rm R_{\odot }$), shifted from 60$^{\circ }$N to 35$^{\circ }$N, introducing a latitude-dependent solar rotation component into the observed Doppler velocities. This component was reflected in the sky spectra obtained during the final crescent phase, where scattered light from the local region on solar east limb carried the Doppler signature of rotation near 60$^{\circ }$N and 50$^{\circ }$N. We estimated rotation baselines at the relevant latitudes under solid-body rotation. The baselines were considered when analysing the intrinsic velocity of local plasma motions, as exhibited in the flash and coronal spectra. After accounting for solar rotation, photospheric emission lines appeared nearly static, chromospheric emission lines exhibited additional blueshifts between $-1$ and $-3\ \rm km\ s^{-1}$ at all latitudes, the coronal emission line (Fe xiv 5303 Å) showed an additional blueshift of approximately $-2\ \rm km\ s^{-1}$ in the quiet inner corona at higher latitude, and a maximum additional blueshift of about $-6\ \rm km\ s^{-1}$ at low latitude (35$^{\circ }$N) at a helmet streamer base. These results offer insight into local plasma dynamics across the solar atmospheric layers from a side-on perspective.