Speaker
Description
Cosmogenic radionuclide $^{36}$Cl serves as an important proxy for reconstructing past solar variability, geomagnetic field intensity, and atmospheric circulation. However, global modeling of $^{36}$Cl remains challenging, particularly due to uncertainties in representing stratospheric chlorine processes. In this study, we implement a new configuration of the chemistry-climate model SOCOL-AERv2 that includes an explicit, fully interactive stratospheric chlorine cycle for $^{36}$Cl. We conduct multi-decadal simulations covering the pre-nuclear era (1894–1941), when atmospheric $^{36}$Cl was produced exclusively by cosmic rays. Two modeling approaches are evaluated: one in which $^{36}$Cl participates in the full interactive chlorine chemistry, and another in which it is represented as a passive gaseous tracer transported without chemical feedbacks. Our results indicate that both configurations produce very similar large-scale distributions, transport pathways, and deposition patterns of $^{36}$Cl. This suggests that detailed interactive chlorine chemistry exerts only a minor influence on the global behaviour of cosmogenic $^{36}$Cl. Consequently, simplified transport-only representations may be sufficient for many applications, enabling more computationally efficient simulations.