Chromospheric Waves Observed in HeI (1083 nm)- a Closer Look

Although "Moreton" waves have historically been observed in H-alpha data, more recently waves have also been observed in chromospheric He I (1083 nm) images. In a previous study, we found that chromospheric waves observed in He I data (from the Mauna Loa Solar Observatory) in two events are co-spatial with the corresponding coronal waves observed by EIT (Fe XII 19.5 nm). In an effort to better understand the nature of chromospheric waves, we focus on these two wave events observed in He I in which two interesting phenomena occur: the waves are visible in the He I velocity data, and multiple waves are observed for each event. We suggest the velocity signal is a result of slow-mode wave compression followed by a slow-mode wave rarefaction in the chromosphere. We also suggest the observed multiple waves indicate more than one driving mechanism may be involved .