Representation of atmosphere induced heterogeneity in land – atmosphere interactions in E3SM-MMFv2

Abstract. In E3SM-MMF, where parameterizations of convection and turbulence are replaced by 2-D CRM, there are multiple options to represent land-atmosphere interactions. Here, we propose 3 different coupling strategies: 1) coupling of a single land surface model to the global grid (MMF), 2) coupling a single land instance directly to the embedded CRM (SFLX2CRM), and 3) coupling multiple land instances to each column of the CRM grid (MAML). In MAML (Multi-Atmosphere Multi-Land) framework, a land model is coupled to CRM at CRM grid scale by coupling an individual copy of a land model to each CRM grid. Therefore, we can represent intra-CRM heterogeneity in the land-atmosphere interaction processes. 5-year global simulations are run using these 3 coupling strategies and we find that there are little to no difference whether a land model is coupled to CRM or a global atmosphere. In MAML, spatial heterogeneity within CRM induces stronger turbulence, which leads to the changes in soil moisture, surface heat fluxes and precipitation. However, the differences of MAML from the other two cases are rather weak, suggesting that the impact of using MAML does not justify the increase in cost.