This paper provides a systematic evaluation of the ability of 12 Earth System Models(ESMs)participating in the Coupled Model Intercomparison Project Phase 6(CMIP6)to simulate the spatial inhomogeneity of the atmospher...This paper provides a systematic evaluation of the ability of 12 Earth System Models(ESMs)participating in the Coupled Model Intercomparison Project Phase 6(CMIP6)to simulate the spatial inhomogeneity of the atmospheric carbon dioxide(CO_(2))concentration.The multi-model ensemble mean(MME)can reasonably simulate the increasing trend of CO_(2) concentration from 1850 to 2014,compared with the observation data from the Scripps CO_(2) Program and CMIP6 prescribed data,and improves upon the CMIP5 MME CO_(2) concentration(which is overestimated after 1950).The growth rate of CO_(2) concentration in the northern hemisphere(NH)is higher than that in the southern hemisphere(SH),with the highest growth rate in the mid-latitudes of the NH.The MME can also reasonably simulate the seasonal amplitude of CO_(2) concentration,which is larger in the NH than in the SH and grows in amplitude after the 1950s(especially in the NH).Although the results of the MME are reasonable,there is a large spread among ESMs,and the difference between the ESMs increases with time.The MME results show that regions with relatively large CO_(2) concentrations(such as northern Russia,eastern China,Southeast Asia,the eastern United States,northern South America,and southern Africa)have greater seasonal variability and also exhibit a larger inter-model spread.Compared with CMIP5,the CMIP6 MME simulates an average spatial distribution of CO_(2) concentration that is much closer to the site observations,but the CMIP6-inter-model spread is larger.The inter-model differences of the annual means and seasonal cycles of atmospheric CO_(2) concentration are both attributed to the differences in natural sources and sinks of CO_(2) between the simulations.展开更多
Drought and water shortage are the biggest limiting factors of dry farming,and variety plays an important role in an increase in the yield of dryland maize.Screening high-yield maize varieties is helpful to the contin...Drought and water shortage are the biggest limiting factors of dry farming,and variety plays an important role in an increase in the yield of dryland maize.Screening high-yield maize varieties is helpful to the continuous increase and stable yield of dryland grain.In this experiment,the growth period,characters and yield of 12 maize varieties were analyzed.The results show that the yield of Ganyu series was low,while the yield of Lianda 169 was the highest(8 080.93 kg/ha),which was 31.40% higher than Jinsui 4.The yield of Dunyu 16 was6 621.06 kg/ha,7.64% higher than Jinsui 4.The two varieties had good comprehensive characters,so they could be popularized and planted in dry farming areas of Lanzhou City.展开更多
In the Nino3.4 region(tropical Pacific,5°S-5°N,170°-120°W),sea surface temperature(SST)changes are highly correlated with temperature variations in the upper 40-m layer.This study explores the uppe...In the Nino3.4 region(tropical Pacific,5°S-5°N,170°-120°W),sea surface temperature(SST)changes are highly correlated with temperature variations in the upper 40-m layer.This study explores the upper-ocean heat budget in the Nino3.4 region using Ocean Reanalysis System 5(ORAS5)monthly data from 1979 to 2018,with a focus on ocean heat transports at lateral boundaries in the top 40-m layer and their correlation with temperature variations.In the region,there is a well-defined structure of opposite meridional circulation in the upper and lower parts of the thermocline,characterized by divergence in the upper layer above 40 m and convergence in the lower layer.The change of mean temperature in the upper layer is determined by the sum of zonal,meridional,and vertical heat transports,which,however,tend to largely compensate for each other.In general,part of the surface heat flux from the atmosphere to the ocean and the heat transport from the subsurface ocean are transported out of the domain by meridional and zonal currents,leaving only a tiny part to warm or cool the upper ocean.The amplitude of the net surface heat flux effective for the entire 40-m layer of the ocean is weaker than the lateral heat transport.On an interannual timescale,variations of heat transports in both zonal and meridional are positively correlated with temperature anomalies,while the vertical heat transport from the subsurface ocean is negatively correlated.Composite analyses for five El Nino events and five La Nina events also revealed that there is a positive contribution of horizontal transport convergence to temperature anomalies during the evolution of El Nino(warming)and La Nina(cooling),while vertical transport acts against temperature variations.展开更多
Atmospheric CO_(2) concentration is characterized by spatial inhomogeneity and seasonal variability.The response of surface air temperature(SAT)to the inhomogeneity in CO_(2) concentration globally and regionally rema...Atmospheric CO_(2) concentration is characterized by spatial inhomogeneity and seasonal variability.The response of surface air temperature(SAT)to the inhomogeneity in CO_(2) concentration globally and regionally remains elusive.In this study,the BCC-CSM2-MR climate model was used to investigate the differences in global SAT in response to the spatially inhomogeneous distribution of atmospheric CO_(2) concentration.The analysis was based on three historical experiments(Hist_1dCO_(2),Hist_2dCO_(2),and Hist_3dCO_(2))conducted separately under the forcing of globally homogeneous,zonally homogeneous,and wholly spatially inhomogeneous CO_(2) concentrations from 1850 to 2014,derived from 12 Earth System Models of the Coupled Model Intercomparison Project Phase 6.The simulation results revealed similar trends of evolution in the global mean SATs in the 20th century under the three CO_(2) concentration distributions,and showed that the simulated historical SATs considering the meridional inhomogeneity of CO_(2) concentration in Hist_2dCO_(2) and the wholly spatial inhomogeneity in Hist_3dCO_(2) were more consistent with the observations.Compared with the results of Hist_1dCO_(2),the SATs in Hist_2dCO_(2) were warmer over land in the mid–high latitudes of the Northern Hemisphere(NH)than over other land areas.Further consideration of the zonally inhomogeneous CO_(2) concentration in Hist_3dCO_(2) revealed generally colder SATs over the NH mid–high-latitude ocean than over land at the same latitudes,and even the zonal mean SATs in the NH were slightly colder than those in Hist_2dCO_(2).These differences are ascribed to the uneven distribution of CO_(2) concentration along the same latitude in the NH in Hist_3dCO_(2),which leads to strong large-scale fluctuations in the atmospheric circulation.Eurasia is the region with the highest concentration of atmospheric CO_(2),which leads to remarkable regional SAT warming owing to enhanced downward longwave radiation.Warmer SATs in Eurasia in winter will further strengthen the northwesterly winds over eastern Asia,resulting in an increase in sea ice and strengthened cold SAT anomalies over the northern North Pacific.The simulated varied responses of the atmospheric circulation and SAT to inhomogeneous CO_(2) forcing highlight the imperative need for refined representation of the inhomogeneity of the atmospheric CO_(2) distribution in climate models for more accurate assessment of climate change.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.42230608)the UK-China Research&Innovation Partnership Fund through the Met Office Climate Science for Service Partnership(CSSP)China as part of the Newton Fund.
文摘This paper provides a systematic evaluation of the ability of 12 Earth System Models(ESMs)participating in the Coupled Model Intercomparison Project Phase 6(CMIP6)to simulate the spatial inhomogeneity of the atmospheric carbon dioxide(CO_(2))concentration.The multi-model ensemble mean(MME)can reasonably simulate the increasing trend of CO_(2) concentration from 1850 to 2014,compared with the observation data from the Scripps CO_(2) Program and CMIP6 prescribed data,and improves upon the CMIP5 MME CO_(2) concentration(which is overestimated after 1950).The growth rate of CO_(2) concentration in the northern hemisphere(NH)is higher than that in the southern hemisphere(SH),with the highest growth rate in the mid-latitudes of the NH.The MME can also reasonably simulate the seasonal amplitude of CO_(2) concentration,which is larger in the NH than in the SH and grows in amplitude after the 1950s(especially in the NH).Although the results of the MME are reasonable,there is a large spread among ESMs,and the difference between the ESMs increases with time.The MME results show that regions with relatively large CO_(2) concentrations(such as northern Russia,eastern China,Southeast Asia,the eastern United States,northern South America,and southern Africa)have greater seasonal variability and also exhibit a larger inter-model spread.Compared with CMIP5,the CMIP6 MME simulates an average spatial distribution of CO_(2) concentration that is much closer to the site observations,but the CMIP6-inter-model spread is larger.The inter-model differences of the annual means and seasonal cycles of atmospheric CO_(2) concentration are both attributed to the differences in natural sources and sinks of CO_(2) between the simulations.
基金Supported by Planning Project of Lanzhou Science and Technology Bureau(2015-3-60)
文摘Drought and water shortage are the biggest limiting factors of dry farming,and variety plays an important role in an increase in the yield of dryland maize.Screening high-yield maize varieties is helpful to the continuous increase and stable yield of dryland grain.In this experiment,the growth period,characters and yield of 12 maize varieties were analyzed.The results show that the yield of Ganyu series was low,while the yield of Lianda 169 was the highest(8 080.93 kg/ha),which was 31.40% higher than Jinsui 4.The yield of Dunyu 16 was6 621.06 kg/ha,7.64% higher than Jinsui 4.The two varieties had good comprehensive characters,so they could be popularized and planted in dry farming areas of Lanzhou City.
基金Supported by the National Key Research and Development Program of China(2016YFA0602100)Strategic Priority Research Program of Chinese Academy of Sciences(XDB 40000000,XDB 42000000,and XDA19060102)National Natural Science Foundation of China[42030410 and 41690122(41690120)]。
文摘In the Nino3.4 region(tropical Pacific,5°S-5°N,170°-120°W),sea surface temperature(SST)changes are highly correlated with temperature variations in the upper 40-m layer.This study explores the upper-ocean heat budget in the Nino3.4 region using Ocean Reanalysis System 5(ORAS5)monthly data from 1979 to 2018,with a focus on ocean heat transports at lateral boundaries in the top 40-m layer and their correlation with temperature variations.In the region,there is a well-defined structure of opposite meridional circulation in the upper and lower parts of the thermocline,characterized by divergence in the upper layer above 40 m and convergence in the lower layer.The change of mean temperature in the upper layer is determined by the sum of zonal,meridional,and vertical heat transports,which,however,tend to largely compensate for each other.In general,part of the surface heat flux from the atmosphere to the ocean and the heat transport from the subsurface ocean are transported out of the domain by meridional and zonal currents,leaving only a tiny part to warm or cool the upper ocean.The amplitude of the net surface heat flux effective for the entire 40-m layer of the ocean is weaker than the lateral heat transport.On an interannual timescale,variations of heat transports in both zonal and meridional are positively correlated with temperature anomalies,while the vertical heat transport from the subsurface ocean is negatively correlated.Composite analyses for five El Nino events and five La Nina events also revealed that there is a positive contribution of horizontal transport convergence to temperature anomalies during the evolution of El Nino(warming)and La Nina(cooling),while vertical transport acts against temperature variations.
基金Supported by the National Natural Science Foundation of China(42230608).
文摘Atmospheric CO_(2) concentration is characterized by spatial inhomogeneity and seasonal variability.The response of surface air temperature(SAT)to the inhomogeneity in CO_(2) concentration globally and regionally remains elusive.In this study,the BCC-CSM2-MR climate model was used to investigate the differences in global SAT in response to the spatially inhomogeneous distribution of atmospheric CO_(2) concentration.The analysis was based on three historical experiments(Hist_1dCO_(2),Hist_2dCO_(2),and Hist_3dCO_(2))conducted separately under the forcing of globally homogeneous,zonally homogeneous,and wholly spatially inhomogeneous CO_(2) concentrations from 1850 to 2014,derived from 12 Earth System Models of the Coupled Model Intercomparison Project Phase 6.The simulation results revealed similar trends of evolution in the global mean SATs in the 20th century under the three CO_(2) concentration distributions,and showed that the simulated historical SATs considering the meridional inhomogeneity of CO_(2) concentration in Hist_2dCO_(2) and the wholly spatial inhomogeneity in Hist_3dCO_(2) were more consistent with the observations.Compared with the results of Hist_1dCO_(2),the SATs in Hist_2dCO_(2) were warmer over land in the mid–high latitudes of the Northern Hemisphere(NH)than over other land areas.Further consideration of the zonally inhomogeneous CO_(2) concentration in Hist_3dCO_(2) revealed generally colder SATs over the NH mid–high-latitude ocean than over land at the same latitudes,and even the zonal mean SATs in the NH were slightly colder than those in Hist_2dCO_(2).These differences are ascribed to the uneven distribution of CO_(2) concentration along the same latitude in the NH in Hist_3dCO_(2),which leads to strong large-scale fluctuations in the atmospheric circulation.Eurasia is the region with the highest concentration of atmospheric CO_(2),which leads to remarkable regional SAT warming owing to enhanced downward longwave radiation.Warmer SATs in Eurasia in winter will further strengthen the northwesterly winds over eastern Asia,resulting in an increase in sea ice and strengthened cold SAT anomalies over the northern North Pacific.The simulated varied responses of the atmospheric circulation and SAT to inhomogeneous CO_(2) forcing highlight the imperative need for refined representation of the inhomogeneity of the atmospheric CO_(2) distribution in climate models for more accurate assessment of climate change.
