Heterogeneous halogen chemistry plays a dominant role in driving changes in polar chemical composition and ozone depletion. Activation of halogens outside the polar regions may result in depletion of local ozone, along with changes in the chemical budgets of various species in the lower stratosphere (LS). In this paper, both the means and distributions of NO₂ measurements from the Stratospheric Aerosol and Gas Experiment III (SAGE3m) are compared to simulations from a coupled climate-chemistry model, in order to better characterize and quantify subpolar heterogeneous halogen chemistry. Observations of NO₂ from SAGE3m are found to be drawn from the same distribution as the model simulation with heterogeneous chemistry, but from a different distribution than the simulation without heterogeneous chemistry. Results indicate that heterogeneous chemistry plays a significant role in determining the chemical composition of the subpolar LS and show how analysis of distribution functions can provide useful insights to chemical processes.