10.5 Subseasonal prediction in a global convection-permitting model: insights and challenges in simulating tropical convection and extratropical teleconnections.
Weber, Nick, and Cliff Mass, University of Washington
This talk presents
results from four 28-day global simulations using MPAS at 3-km resolution.
These runs are motivated by the previously studied benefits of convection-permitting
resolution for simulated tropical convection, the MJO, and forecast biases, all
of which have a substantial impact on global extended prediction.
In addition to the results of the 3-km global MPAS simulations, 15-km runs with
and without convective parameterization will be described, as well as one
“tropical channel” simulation with 3-km resolution in the tropics transitioning
to 15-km grid spacing in the extratropics.
The talk presents tropical precipitation statistics for all cases and
configurations to address the impact of convection-permitting resolution and
cumulus parameterization on the frequency and intensity of convection. The
structure and propagation of the MJO are compared among the MPAS simulations,
highlighting a tendency for the convection-permitting configuration to more
faithfully produce large-scale organized convection. Convection-permitting
simulations, on average, also tend to produce more accurate week-3
extratropical 500hPa height anomalies. In addition to these results, we discuss
the relationship between tropical convection and moisture, the 3-dimensional
structure of large-scale convection in the different simulation configurations,
the connection between tropical convection and extratropical circulation patterns
like the PNA, and potential future experiments.