Implementation of Sub‐Grid Scale Temperature Perturbations Induced by Non‐Orographic Gravity Waves in WACCM6

Abstract

Atmospheric gravity waves can play a significant role on atmospheric chemistry throughtemperature fluctuations. A recent modeling study introduced a method to implement subgrid‐scale orographicgravity‐wave‐induced temperature perturbations in the Whole Atmosphere Community Climate Model(WACCM). The model with a wave‐induced temperature parameterization was able to reproduce for example,the influence of mountain wave events on atmospheric chemistry, as highlighted in previous literature. Here weextend the subgrid‐scale wave‐induced temperature parameterization to also include non‐orographic gravitywaves arising from frontal activity and convection. We explore the impact of these waves on middle atmospherechemistry, particularly focusing on reactions that are strongly sensitive to temperature. The non‐orographicgravity waves increase the variability of chemical reaction rates, especially in the lower mesosphere. As anexample, we show that this, in turn, leads to increases in the daytime ozone variability. To demonstrate anotherimpact, we briefly investigate the role of non‐orographic gravity waves in cirrus cloud formation in this model.Consistent with findings from the previous study focusing on orographic gravity waves, non‐orographic wavesalso enhance homogeneous nucleation and increase cirrus clouds. The updated method used enables the globalchemistry‐climate model to account for both orographic and non‐orographic gravity‐wave‐induced subgrid‐scale dynamical perturbations in a consistent manner.