Regional climate simulation of tropical cyclone at gray-zone resolution
over Western North Pacific: With/without cumulus parameterization
Abstract
Tropical cyclones (TCs) simulated at gray-zone resolution (9km) in the
Advanced Research version of the Weather Research and Forecasting Model
(WRF-ARW) are performed and evaluated over the Western North Pacific
(WNP). Two sets of experiments are carried out to test the effect the
cumulus parameterization (CPS), driven by the European Center for
Medium-Range Weather Forecasts (ECMWF) fifth-generation global
atmospheric reanalysis (ERA5), over 11-year (2008-2018) TC seasons
(June–November). Through comparisons with the observation and
reanalysis, it is shown that the ICPS (involving CPS) experiment yields
good skills in simulating TC frequency due to more realistic large-scale
mean states, including stronger low-tropospheric circulation, wetter
mid-tropospheric environment and more active ascending motion over TC
main development region (MDR). On the other hand, the NICPS (not
involving CPS) experiment is found to better reproduce intense TCs
(Saffir-Simpson hurricane categories 3, 4 and 5) in terms of intensity,
accumulated cyclone energy (ACE) and inner-core size. Although NICPS can
capture TC inner-core structure well with stronger radial inflow in the
boundary layer, rising motion around the eyewall and outflow in the mid
to upper troposphere, NICPS significantly underestimates TC outer size
due to rapidly decay of TC outer wind field, suggesting limited severe
convective activities in the outer region.