Arnold, N. P., W. M. Putman, and S. R. Freitas, 2020: Impact of resolution and parameterized convection on the diurnal cycle of precipitation in a global nonhydrostatic model. J. Meteor. Soc. Japan, 98, https://doi.org/10.2151/jmsj.2020-066
Plain Language Summary: We evaluate the diurnal cycle of precipitation and organized convection in a set of nonhydrostatic global model runs with horizontal grid spacing ranging from 50 km to 3.5 km, using the NASA GEOS model, with scale-aware Grell-Freitas parameterized convection. The 3.5 km experiments are repeated with Grell-Freitas turned off, and again with scale-awareness disabled, to illustrate the impact of parameterized convection.
- High resolution shows greatest benefit in regions dominated by non-local propagating convection, but produces peaks too early in the day in locally-forced regions.
- Experiments with strong parameterized convection show diurnal amplitudes similar to the observed climatology, whereas those relying on explicit convection develop unrealistic small-scale variability.
- Some parameterized deep convection is beneficial for the diurnal amplitude and phase even with a 3.5 km model grid, but only when throttled with the scale-aware approach.