This study provides a comprehensive evaluation of historical surface soil moisture simulation(1979-2012)over Eurasia at annual and seasonal time scales between two medium-resolution versions of the Beijing Climate Cen...This study provides a comprehensive evaluation of historical surface soil moisture simulation(1979-2012)over Eurasia at annual and seasonal time scales between two medium-resolution versions of the Beijing Climate Center Climate System Model(BCC-CSM)—one that is currently participating in phase 6 of the Coupled Model Intercomparison Project(CMIP6),i.e.,BCC-CSM2-MR,and the other,BCC-CSM1.1m,which participated in CMIP5.We show that BCC-CSM2-MR is more skillful in reproducing the climate mean states and standard deviations of soil moisture,with pattern correlations increased and biases reduced significantly.BCC-CSM2-MR performs better in capturing the first two primary patterns of soil moisture anomalies,where the period of the corresponding time series is closer to that of reference data.Comparisons show that BCC-CSM2-MR performs at a high level among multiple models of CMIP6 in terms of centered pattern correlation and“amplitude of variation”(relative standard deviation).In general,the centered pattern correlation of BCC-CSM2-MR,ranging from 0.61 to 0.87,is higher than the multi-model mean of CMIP6,and the relative standard deviation is 0.75,which surmounts the overestimations in most of the CMIP6 models.Due to the vital role played by precipitation in land-atmosphere interaction,possible causes of the improvement of soil moisture simulation are further related to precipitation in BCC-CSM2-MR.The results indicate that a better description of the relationship between soil moisture and precipitation and a better reproduction of the climate mean precipitation by the model may result in the improved performance of soil moisture simulation.展开更多
We evaluated the ability of the Beijing Climate Center models on different horizontal resolutions(BCC-CSM1.1 on approximately 280-km resolution and BCC-CSM1.1 m on approximately 110-km resolution) in simulating the ne...We evaluated the ability of the Beijing Climate Center models on different horizontal resolutions(BCC-CSM1.1 on approximately 280-km resolution and BCC-CSM1.1 m on approximately 110-km resolution) in simulating the nearsurface wind speeds(NWS) in China during 1961–2005. The spatial distribution of the annual mean NWS over China is better captured by BCC-CSM1.1 m than by BCC-CSM1.1 due to the finer resolution. The weakened NWS over China during 1961–2005 cannot be reproduced by BCC-CSM1.1, whereas BCC-CSM1.1 m is able to simulate the decreasing trend of the autumn NWS in North China, although the magnitude is about 1/3 of the observed value.This is attributed to the better performance of this finer-resolution model in reproducing the increase in sea level pressure over Mongolia and North China over the past 45 years. The results suggest that increasing the horizontal resolution of the BCC-CSM model has improved its ability in reproducing the spatial distribution and long-term changes of NWS over China. Future projections by BCC-CSM1.1 m under different Representative Concentration Pathway(RCP) scenarios demonstrate that the autumn NWS in North China will decrease during the 21 st century under both the middle(RCP4.5) and high(RCP8.5) emission scenarios, with a higher decreasing rate under RCP8.5.展开更多
基金supported by the National Key Research and Development Program of China(Grant Nos.2018YFC1506004 and 2016YFA0602602).
文摘This study provides a comprehensive evaluation of historical surface soil moisture simulation(1979-2012)over Eurasia at annual and seasonal time scales between two medium-resolution versions of the Beijing Climate Center Climate System Model(BCC-CSM)—one that is currently participating in phase 6 of the Coupled Model Intercomparison Project(CMIP6),i.e.,BCC-CSM2-MR,and the other,BCC-CSM1.1m,which participated in CMIP5.We show that BCC-CSM2-MR is more skillful in reproducing the climate mean states and standard deviations of soil moisture,with pattern correlations increased and biases reduced significantly.BCC-CSM2-MR performs better in capturing the first two primary patterns of soil moisture anomalies,where the period of the corresponding time series is closer to that of reference data.Comparisons show that BCC-CSM2-MR performs at a high level among multiple models of CMIP6 in terms of centered pattern correlation and“amplitude of variation”(relative standard deviation).In general,the centered pattern correlation of BCC-CSM2-MR,ranging from 0.61 to 0.87,is higher than the multi-model mean of CMIP6,and the relative standard deviation is 0.75,which surmounts the overestimations in most of the CMIP6 models.Due to the vital role played by precipitation in land-atmosphere interaction,possible causes of the improvement of soil moisture simulation are further related to precipitation in BCC-CSM2-MR.The results indicate that a better description of the relationship between soil moisture and precipitation and a better reproduction of the climate mean precipitation by the model may result in the improved performance of soil moisture simulation.
基金Supported by the National Key Research and Development Program of China(2016YFE0102400 and 2016YFC0202100)
文摘We evaluated the ability of the Beijing Climate Center models on different horizontal resolutions(BCC-CSM1.1 on approximately 280-km resolution and BCC-CSM1.1 m on approximately 110-km resolution) in simulating the nearsurface wind speeds(NWS) in China during 1961–2005. The spatial distribution of the annual mean NWS over China is better captured by BCC-CSM1.1 m than by BCC-CSM1.1 due to the finer resolution. The weakened NWS over China during 1961–2005 cannot be reproduced by BCC-CSM1.1, whereas BCC-CSM1.1 m is able to simulate the decreasing trend of the autumn NWS in North China, although the magnitude is about 1/3 of the observed value.This is attributed to the better performance of this finer-resolution model in reproducing the increase in sea level pressure over Mongolia and North China over the past 45 years. The results suggest that increasing the horizontal resolution of the BCC-CSM model has improved its ability in reproducing the spatial distribution and long-term changes of NWS over China. Future projections by BCC-CSM1.1 m under different Representative Concentration Pathway(RCP) scenarios demonstrate that the autumn NWS in North China will decrease during the 21 st century under both the middle(RCP4.5) and high(RCP8.5) emission scenarios, with a higher decreasing rate under RCP8.5.
