LMDZ4,a variable-resolution global atmospheric general circulation model,is assessed against observed data in Southeast Asia before its further utilization in climate change downscaling studies.The model is developed in the Laboratoire de Météorologie Dynamique in Paris,as the atmospheric component of the ocean-atmosphere coupled system IPSL-CM5A.In order to investigate the ability of LMDZ4 in simulating East Asian summer precipitation,temperature and circulation,this paper analyzes the causes of simulation deviation and some of the uncertainties in this model.The study is expected to lay a foundation for further forecasting of future climate changes.In this study,LMDZ4 has its domain centered over Southeast Asia[domain center at (30°N,110°E);coverage: (5-55°N,85-135°E)],and is driven by ERA-Interim reanalysis data from 1979 to 2009.It is actually used as a traditional limited-area model with the whole globe as the buffer zone that receives the ERA-Interim data.The nudged variables include zonal wind,meridional wind,temperature and specific humidity,with a time interval of 6 h.There are 121×120 (latitude×longitude)grids and 19 layers in the vertical direction.The spatial resolution inside the domain is approximately 0.6°×0.6°.The driving forcing is added through a relaxation procedure.We impose a long (10 days,but not infinite,to be comparable with other simulations using this historical set-up)relaxation time scale inside the domain,while the relaxation time scale outside the domain is 1.5 h.The use of two distinct relaxation time scales inside and outside the domain enables the model to run almost freely inside the domain,whereas it completely follows the forcing outside the domain.For the purpose of model assessment,daily temperature and rainfall at a few meteorological stations in China are used.These two datasets are available with a resolution of 0.5°×0.5°.Results show that the mean state of the major atmospheric general circulation systems can be simulated well,including the South Asian High,westerly jet,western Pacific subtropical high,and moisture transport.The main characteristics of rainfall and surface air temperature are also successfully reproduced.Nevertheless,the simulation shows some biases.Wet and cold biases are found over southern coastal areas,warm and dry biases over the Huaihe river basin,and warm and wet biases over northeast regions,which are related to the simulation deviations of mid-upper level circulations.For example,the simulated strengths of the South Asian high and westerly jet stream are too weak,while the water vapor transport from the Indian Ocean is stronger,leading to more rainfall over southern coastal areas.The missed rainfall belt along the Yangtze River Valley is due to a lack of moisture brought by southeast winds that are too weak,and is directly related to the weak western Pacific subtropical high,which leads to less moisture over western Pacific regions.The deviations mentioned above may largely be attributable to the cloud parameterization scheme in LMDZ4,which yields insufficient cloud cover.In addition,the coarse vertical resolution in this model version is also thought to be a factor contributing to some of the imperfections in upper-level circulation,and to model biases.As we use only one regional climate model driven by one set of reanalysis data,we cannot fully explore the uncertainties of this model in terms of climate changes for precipitation and temperature.It is clear that more research is needed to assess these uncertainties.We need to include as many different types of downscaling model (e.g.,dynamical and statistical downscaling)as possible when generating climate-change information at the local scale.