Comparison Research Of Observation And Reanalysis Data Over China

The ability of reanalysis data in describing real climatology and climate change has been widely concerned.Based on quality controlled,homogenized and urbanization-bias adjused temperature data from 685 surface stations for period of 1961-2015,homogenized temperature data from 16 stations for period of 1909-2010 in eastern China,and homogenized radiosonde temperature and humidity data from 118 stations for period of 1979-2015,and eight reanalysis datasets of NCEPv1?NCEPv2?ERA20C?ERAinterim?JRA55?20CR?MERRA and CFSR,a comparison of surface air temperature,upper air temperature and upper air humidity over China between obserbations and the eight reanalysis was undertaken.The averages,periodicals,correlations,standard deviations and linear trends during 1909—2010,1961—2015,1979—2015 derived from observation data and reanalysis datasets were analyzed.The resultsshow that: 1)The inter-annual variability and 2.5—5 periodicals have a good consistency between reanalysis and observation.The surface air temperature of reanalysis data were generally 0—2? lower than observation;2)The correlation and standard deviation ratio between the reanalysis data and observations demonstrated a higher consistency of inter—annual variability and dispersion for ERAinterim and JRA55;3)The inter—annual and decadal variability were consistent between reanalysis data and observations in eastern China after 1979,but the reanalysis data exhibited a large fluctuation during the 1960 s.The average 20 CR surface air temperature was lower than the observations during 1920–1950,and ERA20 C was generally closer to the observational temperatures than 20 CR during 1909–2010;4)The linear trends of surface air temperature showed clear warming in reanalysis datasets and the observations,but the reanalysis trends were significantly smaller than the observational trends for annual mean temperature,with NCEPV1 more consistent with the urbanization-bias adjusted data in terms of linear trends;5)The difference of annual mean temperature between observations and reanalysis data becomes larger with increase in elevation;6)Most reanalysis data were cooler and wetter than observations in the troposphere and warmer in the stratosphere;7)The correlations of radiosonde temperature between reanalysis and homogenized data were higher than those between reanalysis and unhomogenized data.JRA55,ERAinterim and MERRA were closer to observation datain this regard.The correlation and standard deviation ratio of radiosonde humidity demonstrated the higher consistence of annual variability and dispersion in the lower troposphere,butthe dispersion of reanalysis were obviously higher than homogenized data in the middle and upper troposphere.ERA20 C was generally closer to the observational humidity;8)The linear trends of radiosonde temperature are consistent between observation and reanalysis data with warming in the lower and middle troposphere and cooling in the lower stratosphere.The linear trends of specific humidity from reanalysis data were consistent with wetting trends in the lower troposphere,while different in the middle troposphere with drying trends.The linear trends of relative humidity in the troposphere were consistent with drying trends from reanalysis data.Overall,for the climatology and climate change in China,ERAinterim and JRA55 were generally closer to the observational temperatures,and ERA20 C was generally closer to the temperatures in 1909—2010 and upair humidity.