Object-based evaluation of precipitation systems in
convection-permitting regional climate simulation over eastern China
Abstract
Based on the object-based tracking algorithm, the precipitation
simulation ability of the convection-permitting (CP) regional climate
models (RCMs) is evaluated from the viewpoints of the precipitation
systems in this work. The characteristics of precipitation systems over
eastern China during 1998-2007 derived from the Weather Research and
Forecasting model (WRF) with the horizontal grid spacing of
~ 4 km are compared with CMORPH. On the whole, CP RCMs
can capture the average duration and eccentricity of all precipitation
systems reasonably. However, precipitation systems tend to be stronger
but with smaller coverage area in CP RCMs, which leads to the wet biases
and dry biases of accumulated precipitation amount in the
longer-duration (>= 48 hr) and shorter-duration
(< 48 hr) systems, respectively. Such deficiencies in
accumulated precipitation amount of precipitation systems with various
durations can be made up by employing spectral nudging technique in CP
RCMs to a certain degree. This work further indicates that, to improve
the capability of precipitation simulation in CP RCMs, the relationship
between intensity and coverage area of precipitation systems should be
described properly in CP RCMs, especially for those with
shorter-duration.