loading page

Improved Precipitation Diurnal Cycle in GFDL Climate Models with Non-Equilibrium Convection
  • +1
  • Bosong Zhang,
  • Leo J. Donner,
  • Ming Zhao,
  • Zhihong Tan
Bosong Zhang
Princeton University

Corresponding Author:[email protected]

Author Profile
Leo J. Donner
National Oceanic and Atmospheric Administration (NOAA)
Author Profile
Ming Zhao
Author Profile
Zhihong Tan
Princeton University
Author Profile


Most global climate models with convective parameterization have trouble in simulating the observed diurnal cycle of convection. Maximum precipitation usually happens too early during summertime, especially over land. Observational analyses indicate that deep convection over land cannot keep pace with rapid variations in convective available potential energy, which is largely controlled by boundary-layer forcing. In this study, a new convective closure in which shallow and deep convection interact strongly, out of equilibrium, is implemented in atmosphere-only and ocean-atmosphere coupled models. The diurnal cycles of convection in both simulations are significantly improved with small changes to their mean states. The new closure shifts maximum precipitation over land later by about three hours. Compared to satellite observations, the diurnal phase biases are reduced by half. Shallow convection to some extent equilibrates rapid changes in the boundary layer at subdiurnal time scales. Relaxed quasi-equilibrium for convective available potential energy holds in significant measure as a result. Future model improvement will focus on the remaining biases in the diurnal cycle, which may be further reduced by including stochastic entrainment and cold pools.
05 Mar 2024Submitted to ESS Open Archive
13 Mar 2024Published in ESS Open Archive