Speaker: Sean P. Santos (GISS/Columbia)
Topic: In the Wrong Place at the Wrong Time? How Time Integration Error Affects Precipitation in the E3SMv1 Global Climate Model

Version 1 of the E3SM atmosphere model is sensitive to choice of time step, particularly with respect to cloud radiative forcing and precipitation. Recent experiments show that reducing the model time step can lead to a higher precipitation efficiency drying out the atmosphere, as well as an increase in extreme precipitation events linked to tropical orography. Most of these effects are not caused by the time integration error associated with any one parameterization, but rather by issues with coupling physics parameterization to one another and to the dynamics using a coarse time step. Understanding these sources of coupling error leads to some possible improvements for reducing the time integration error in future.