Paper detail

Detection of spicules termed Rapid Blue-shifted Excursions as seen in the chromosphere via Hα and the transition region via Si iv 1394 Å line emission

We show signatures of spicules termed Rapid Blue-shifted Excursions (RBEs) in the Si iv 1394 Å emission line using a semi-automated detection approach. We use the Hα filtergrams obtained by the CRISP imaging spectropolarimeter on the Swedish 1-m Solar Telescope and co-aligned Interface Region Imaging Spectrograph data using the SJI 1400 Å channel to study the Spatio-temporal signature of the RBEs in the transition region. The detection of RBEs is carried out using an oriented coronal loop tracing algorithm on Hα Dopplergrams at 35 km s^-1. We find that the number of detected features is significantly impacted by the time-varying contrast values of the detection images, which are caused by the changes in the atmospheric seeing conditions. We detect 407 events with lifetime greater than 32 sec. This number is further reduced to 168 RBEs based on the Hα profile and the proximity of RBEs to the large scale flow. Of these 168 RBEs, 89 of them display a clear Spatio-temporal signature in the SJI 1400 Å channel, indicating that a total of ~53% are observed to have co-spatial signatures between the chromosphere and the transition region.