AutoTAB: Automatic Tracking Algorithm for Bipolar Magnetic Regions

Abstract: Bipolar Magnetic Regions (BMRs) provide crucial information about solar magnetism. They exhibit varying morphology and magnetic properties throughout their lifetime, and studying these properties can provide valuable insights into the workings of the solar dynamo. The majority of previous studies have counted every detected BMR as a new one and have not been able to study the full life history of each BMRs. To address this issue, we have developed an Automatic Tracking Algorithm (AutoTAB) for BMRs, that tracks the BMRs for their entire lifetime or throughout their disk passage. AutoTAB uses the binary maps of detected BMRs to automatically track the regions. This is done by differentially rotating the binary maps of the detected regions and checking for overlaps between them. In this first article of this project, we provide a detailed description of the working of the algorithm and evaluate its strengths and weaknesses by comparing it with existing algorithms. AutoTAB excels in tracking even for the small BMRs (with flux $\sim 10<sup>{20}$ Mx) and it has successfully tracked 9152 BMRs over the last two solar cycles (1996--2020), providing a comprehensive dataset that depicts the evolution of various properties for each BMR. The tracked BMRs exhibit the well-known latitudinal-time distribution and 11 year cyclic variation except for small BMRs which appear at all phases of the solar cycle and show weak latitudinal dependency. Finally, we discuss the possibility of adapting our algorithm to other datasets and expanding the technique to track other solar features in the future.