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Chromospheric swirls are considered to play a significant role in thedynamics and heating of the upper solar atmosphere. It is important toautomatically detect and track them in chromospheric observations and determinetheir properties. We applied a recently developed automated chromospheric swirldetection method to time-series observations of a quiet region of the solarchromosphere obtained in the H$\alpha$-0.2 \r{A} wavelength of the H$\alpha$spectral line by the CRISP instrument at the Swedish 1-m Solar Telescope. Thealgorithm exploits the morphological characteristics of swirling events in highcontrast chromospheric observations and results in the detection of thesestructures in each frame of the time series and their tracking over time. Weconducted a statistical analysis to determine their various properties,including a survival analysis for deriving the mean lifetime. A mean number of146 $\pm$ 9 swirls was detected within the FOV at any given time. The meansurface density is found equal to $\sim$0.08 swirls$ $Mm$^{-2}$ and theoccurrence rate is $\sim$10$^{-2}$ swirls$ $Mm$^{-2}$ min$^{-1}$. These valuesare much higher than those previously reported from chromospheric observations.The radii of the detected swirls range between 0.5 and 2.5 Mm, with a meanvalue equal to 1.3 $\pm$ 0.3 Mm, which is slightly higher than previousreports. The lifetimes range between 1.5 min and 33.7 min with an arithmeticmean value of $\sim$8.5 min. A survival analysis of the lifetimes, however,using the Kaplan-Meier estimator in combination with a parametric model resultsin a mean lifetime of 10.3 $\pm$ 0.6 min. An automated method sheds more lighton their abundance than visual inspection, while higher cadence, higherresolution observations will most probably result in the detection of a highernumber of such features on smaller scales and with shorter lifetimes.

Chromospheric swirls I. Automated detection in H$\alpha$ observations and their statistical properties