Evolution of the critical torus instability height and coronal mass ejection likelihood in solar active regions

Aims. Working towards improved space weather predictions, we aim to quantify how the critical height at which torus instability drives coronal mass ejections (CMEs) varies over time in a sample of solar active regions. Methods. We model magnetic fields 42 regions and their central polarity inversion lines throughout observed lifetimes. then compare these heights changing flux photospheric boundary identify CMEs Results. In our sample, rates per unit are twice as high during phases when is increasing than it decreasing, those flux, rate 63% higher rising falling. Furthermore, support extend results previous studies by demonstrating that generally proportional separation polarities through time. When an region increases, for example continuous emergence expansion bipole, also tends increase. Conversely, decreases, due new, compact bipole line existing or into quiet Sun environment, decrease.