Hi,
We have a simulation using WRFV3.2.1 (this is fixed due to other model infrastructure) using the Morrison 2-moment scheme. In the first few hours of the simulation we see very small negative surface precipitation values, ranging from -1e-30 to as negative as -1e-20.
Right now we're treating them as roundoff and are setting them to zero for our application. However, we're wondering if there is a larger issue with our simulation configuration, or if this behavior is known with the Morrison scheme or other microphysics schemes?
A few other relevant details. The surface precipitation variables are not impacted by advection routines, thus moist_advect_opt and mp_zero_out have no impact. Our configuration uses a grid spacing of 50 km with roughly a 4 minute (240 s) model time step. We've also tested using a 60 second time step with the same results.
Thanks,
Andy
We have a simulation using WRFV3.2.1 (this is fixed due to other model infrastructure) using the Morrison 2-moment scheme. In the first few hours of the simulation we see very small negative surface precipitation values, ranging from -1e-30 to as negative as -1e-20.
Right now we're treating them as roundoff and are setting them to zero for our application. However, we're wondering if there is a larger issue with our simulation configuration, or if this behavior is known with the Morrison scheme or other microphysics schemes?
A few other relevant details. The surface precipitation variables are not impacted by advection routines, thus moist_advect_opt and mp_zero_out have no impact. Our configuration uses a grid spacing of 50 km with roughly a 4 minute (240 s) model time step. We've also tested using a 60 second time step with the same results.
Thanks,
Andy