Evaluation of 12-year Chinese Regional Reanalysis (1998-2009):
Comparison of dynamical downscaling methods with/without local data
Abstract
High-resolution regional reanalysis is one of the most powerful tool to
study local and regional high-impact weather events, climate extremes
and climate change impact. In this study, two high-resolution Chinese
Regional Reanalysis (CNRR) datasets with a resolution of 18km over
1998-2012, which are produced using the Gridpoint Statistical
Interpolation (GSI) data assimilation system and spectral nudging (SN)
technique, were assessed. The reliability of the surface and upper air
variables of the CNRR datasets was evaluated by comparing with in-situ
observations and the European Centre for Medium-Range Forecasts (ECMWF)
ERA-Interim (ERAIN) global reanalysis dataset. The results show that the
CNRR can provide more accurate near-surface variables than the driving
ERAIN global reanalysis. However, special care should be taken when
using the CNRR precipitation dataset, especially for heavy rainfall
cases. CNRR datasets are also able to generate high-quality upper
atmospheric products especially in CNRR-GSI experiment, which
assimilates long time series of local observations. By using the
three-dimensional variational data assimilation (3D-Var) method,
CNRR-GSI outperforms the CNRR-SN and ERAIN. With the increase of the
computing resources, the potential opportunities for improving CNRR can
be expected by applying more advanced methods.