Cirrus located in the tropical tropopause layer (TTL), the transition region between the upper troposphere and lower stratosphere, have a substantial net warming effect that alters the top-of-atmosphere radiation balance. TTL cirrus are strongly related to deep convection, which acts as both a formation mechanism and source of ascent, moisture, and ice in the TTL. Previously, the biases introduced by parameterized convection and the difficulty of simulating convection over land have limited modeling studies of TTL cirrus. To overcome these challenges, this study uses DYAMOND model simulations at their native grid scales to analyze the influence of convection over land on TTL cirrus. The first 10 days of the DYAMOND model runs for FV3 and ICON are considered over a representative 10°x10° latitude-longitude area in western Africa. The model output is then compared to observations taken over the same region. At the grid scale, FV3 and ICON realistically simulate the overall structure and qualitative texture of deep convection. FV3 tends to have deeper convection, more stratiform precipitation, and larger concentrations of cloud ice than ICON, but both models otherwise yield similar results. Radiative and convective variables track well with TTL cirrus, motivating further analysis of the evolution of TTL cirrus and their radiative feedbacks using DYAMOND models. Very high-resolution models like those of the DYAMOND intercomparison enable a thorough study of how TTL cirrus evolve with convection and how these clouds influence the radiative balance in a changing climate. Improved model microphysics and further refinements in grid resolution, especially at high altitudes, will advance our understanding of this important aspect of the climate system.
