Journal Article
Geoscientific Model Development, vol. 12, iss. 7, pp. 2707-2726, 2019
Authors
Chun Zhao, Mingyue Xu, Yu Wang, Meixin Zhang, Jianping Guo, Zhiyuan Hu, L. Ruby Leung, Michael Duda, William Skamarock
Abstract
Abstract. The non-hydrostatic atmospheric Model for Prediction Across Scales (MPAS-A),
a global variable-resolution modeling framework, is applied at a range of
resolutions from hydrostatic (60, 30, 16 km) to non-hydrostatic (4 km)
scales using regional refinement over East Asia to simulate an extreme
precipitation event. The event is triggered by a typical wind shear in the
lower layer of the Meiyu front in East China on 25–27 June 2012 during the
East Asian summer monsoon season. The simulations are evaluated using ground
observations and reanalysis data. The simulated distribution and intensity
of precipitation are analyzed to investigate the sensitivity to model
configuration, resolution, and physics parameterizations. In general,
simulations using global uniform-resolution and variable-resolution meshes
share similar characteristics of precipitation and wind in the refined
region with comparable horizontal resolution. Further experiments at
multiple resolutions reveal the significant impacts of horizontal resolution
on simulating the distribution and intensity of precipitation and updrafts.
More specifically, simulations at coarser resolutions shift the zonal
distribution of the rain belt and produce weaker heavy precipitation centers
that are misplaced relative to the observed locations. In comparison,
simulations employing 4 km cell spacing produce more realistic features of
precipitation and wind. The difference among experiments in modeling rain
belt features is mainly due to the difference in simulated wind shear
formation and evolution during this event. Sensitivity experiments show that
cloud microphysics have significant effects on modeling precipitation at
non-hydrostatic scales, but their impacts are relatively small compared to
that of convective parameterizations for simulations at hydrostatic scales.
This study provides the first evidence supporting the use of
convection-permitting global variable-resolution simulations for studying
and improving forecasting of extreme precipitation over East China and
motivates the need for a more systematic study of heavy precipitation events
and the impacts of physics parameterizations and topography in the future. The key points are as follows.
Model for Prediction Across Scales (MPAS) simulations at global uniform and variable resolutions share similar characteristics of precipitation and wind in the refined region. Numerical experiments reveal significant impacts of resolution on
simulating the distribution and intensity of precipitation and updrafts. This study provides evidence supporting the use of convection-permitting
global variable-resolution simulation to study extreme precipitation.
