Using the historical simulations from 27 models in phase 5 of the Coupled Model Intercomparison Project(CMIP5)and 27 models in phase 6(CMIP6),the authors evaluated the differences between CMIP5 and CMIP6 models in sim...Using the historical simulations from 27 models in phase 5 of the Coupled Model Intercomparison Project(CMIP5)and 27 models in phase 6(CMIP6),the authors evaluated the differences between CMIP5 and CMIP6 models in simulating the climate mean of extreme temperature over China through comparison with observations during 1979–2005.The CMIP6 models reproduce well the spatial distribution of annual maxima of daily maximum temperature(TXx),annual minima of daily minimum temperature(TNn),and frost days(FD).The model spread in CMIP6 is reduced relative to CMIP5 for some temperature indices,such as TXx,warm spell duration index(WSDI),and warm days(TX90 p).The multimodel median ensembles also capture the observed trend of extreme temperature.However,the CMIP6 models still have low skill in capturing TX90 p and cold nights(TN10 p)and have obvious cold biases or warm biases over the Tibetan Plateau.The ability of individual models varies for different indices,although some models outperform the others in terms of the average of all indices considered for different models.By comparing different version models from the same organization,the updated CMIP6 models show no significant difference from their counterparts from CMIP5 for some models.Compared with individual models,the median ensembles show better agreement with the observations for temperature indices and their means.展开更多
Long chain alkyl diols have shown important potential for the reconstruction of sea surface temperature,productivities and upwelling conditions in marine or lacustrine environments.However,little is known about the di...Long chain alkyl diols have shown important potential for the reconstruction of sea surface temperature,productivities and upwelling conditions in marine or lacustrine environments.However,little is known about the distribution and sources of the diols in eastern China marginal seas(CMS),which are areas of important organic carbon sink.Here the contents of C_(30) and C_(32)1,15-diols were analyzed in 181 surface sediments from eastern CMS.The similar distribution pattern and strong linear correlation between C_(30) and C_(32) diols indicated that they had similar biological source,with a dominance of C_(30) diol.Their contents ranged from 7-2726 ng g^(-1) for C_(30) diol and 5-669 ng g^(-1) for C_(32) diol,and both showed higher values mainly in the mud area of the Yellow Sea,while the TOC normalized contents showed a more obvious seaward increasing trend.The similar distribution pattern and significant positive correlation between diols and the other marine biomarkers(brassicasterol,dinosterol,C_(37) alkenones) indicated C_(30) and C_(32) diols in eastern CMS were mainly from marine algae.This conclusion was also supported by principal component analysis(PCA).Our results also showed that sediment diol contents were generally related to marine productivity,suggesting that diols could be applied for marine productivity reconstruction in eastern CMS.展开更多
The authors examine extreme summer temperatures over East China during 19844004 using a regional climate model named CREM (the Climate version of Regional Eta-coordinate Model), which was developed by LASG/IAP. The ...The authors examine extreme summer temperatures over East China during 19844004 using a regional climate model named CREM (the Climate version of Regional Eta-coordinate Model), which was developed by LASG/IAP. The results show that the main features of the extreme summer temperatures over East China are reproduced well by CREM, and the skill for the minimum temperature is higher than that for the maximum tem- perature, especially along the Yangtze-Huai River Valley (YHV). The simulated extreme temperatures are lower than those of observation, especially for the maximum temperature. The bias of extreme temperatures is consistent with the cold bias of the climatological mean summer surface air temperature. The skill of the model in simulating the interannual variability of extreme temperatures increases from north to south. The simulated interannual variation of the minimum temperature is more reasonable than the maximum temperature. The underestimation of net solar radiation at the surface leads to a cold bias of the climatological mean temperature. Furthermore, the model underestimates the light and moderate rain, while overestimates heavy rain. It causes the simulated minimum temperature more reasonable than the maximum temperature.展开更多
One recent study by using instrumental records suggested the correlation between East Asian surface air temperatures(EATs)and the Atlantic Multidecadal Oscillation(AMO)reaches the maximum when the former leads the lat...One recent study by using instrumental records suggested the correlation between East Asian surface air temperatures(EATs)and the Atlantic Multidecadal Oscillation(AMO)reaches the maximum when the former leads the latter by 5–7 years.This seems to disagree with a previous well-realized point that the AMO modulates the decadal variation of EATs,since the atmosphere responds swiftly to sea surface temperature anomalies(SSTA)if therein.It implies that the AMO-EATs correlation should reach the maximum when they are simultaneous or the AMO leads EATs slightly,rather than that the EATs lead the AMO.Thus,this poses an issue about the reality of the newly found lead-lag correlation.Because the instrumental record in the natural climate system may be contaminated by human activities,the EATs-AMO lead-lag correlation derived from the instrumental records may not be a realistic connection of the natural climate system.Thus,whether the connection also exists in the proxies prior to the industrial is essential to answer the issue.In this study the EATs-AMO lead-lag connection is analyzed by using the reconstructed data in the last 500 years,together with the control experimental data with the prescribed pre-industrial forcing in a multiple of coupled climate system models,which attend the international CMIP5 program.The results suggest that the connection,the EATs lead the AMO,also exists in the period from the Little Ice Age(LIA)to the industrial,1500–1860AD.Therefore,the connection may be realistic in the natural climate system.The mechanisms for the connection are then discussed briefly.The results from this paper provide some insights into the connection of the AMO with East Asian climate.展开更多
基金supported by the National Key Research and Development Program of China grant number 2018YFC1509002the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) grant number GML2019ZD0601。
文摘Using the historical simulations from 27 models in phase 5 of the Coupled Model Intercomparison Project(CMIP5)and 27 models in phase 6(CMIP6),the authors evaluated the differences between CMIP5 and CMIP6 models in simulating the climate mean of extreme temperature over China through comparison with observations during 1979–2005.The CMIP6 models reproduce well the spatial distribution of annual maxima of daily maximum temperature(TXx),annual minima of daily minimum temperature(TNn),and frost days(FD).The model spread in CMIP6 is reduced relative to CMIP5 for some temperature indices,such as TXx,warm spell duration index(WSDI),and warm days(TX90 p).The multimodel median ensembles also capture the observed trend of extreme temperature.However,the CMIP6 models still have low skill in capturing TX90 p and cold nights(TN10 p)and have obvious cold biases or warm biases over the Tibetan Plateau.The ability of individual models varies for different indices,although some models outperform the others in terms of the average of all indices considered for different models.By comparing different version models from the same organization,the updated CMIP6 models show no significant difference from their counterparts from CMIP5 for some models.Compared with individual models,the median ensembles show better agreement with the observations for temperature indices and their means.
基金supported by the National Natural Science Foundation of China(Nos.41521064 and 41630966)
文摘Long chain alkyl diols have shown important potential for the reconstruction of sea surface temperature,productivities and upwelling conditions in marine or lacustrine environments.However,little is known about the distribution and sources of the diols in eastern China marginal seas(CMS),which are areas of important organic carbon sink.Here the contents of C_(30) and C_(32)1,15-diols were analyzed in 181 surface sediments from eastern CMS.The similar distribution pattern and strong linear correlation between C_(30) and C_(32) diols indicated that they had similar biological source,with a dominance of C_(30) diol.Their contents ranged from 7-2726 ng g^(-1) for C_(30) diol and 5-669 ng g^(-1) for C_(32) diol,and both showed higher values mainly in the mud area of the Yellow Sea,while the TOC normalized contents showed a more obvious seaward increasing trend.The similar distribution pattern and significant positive correlation between diols and the other marine biomarkers(brassicasterol,dinosterol,C_(37) alkenones) indicated C_(30) and C_(32) diols in eastern CMS were mainly from marine algae.This conclusion was also supported by principal component analysis(PCA).Our results also showed that sediment diol contents were generally related to marine productivity,suggesting that diols could be applied for marine productivity reconstruction in eastern CMS.
基金supported by the China-UK-Swiss Adapting to Climate Change in China Project (ACCC)-Climate Sciencethe Public Science and Technology Research Funds Projects of Ocean (201105019-3)the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-YW- Q11-04)
文摘The authors examine extreme summer temperatures over East China during 19844004 using a regional climate model named CREM (the Climate version of Regional Eta-coordinate Model), which was developed by LASG/IAP. The results show that the main features of the extreme summer temperatures over East China are reproduced well by CREM, and the skill for the minimum temperature is higher than that for the maximum tem- perature, especially along the Yangtze-Huai River Valley (YHV). The simulated extreme temperatures are lower than those of observation, especially for the maximum temperature. The bias of extreme temperatures is consistent with the cold bias of the climatological mean summer surface air temperature. The skill of the model in simulating the interannual variability of extreme temperatures increases from north to south. The simulated interannual variation of the minimum temperature is more reasonable than the maximum temperature. The underestimation of net solar radiation at the surface leads to a cold bias of the climatological mean temperature. Furthermore, the model underestimates the light and moderate rain, while overestimates heavy rain. It causes the simulated minimum temperature more reasonable than the maximum temperature.
基金jointly supported by the National Natural Science Foundation of China(Grant Nos.41375085,41421004)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA05090406)
文摘One recent study by using instrumental records suggested the correlation between East Asian surface air temperatures(EATs)and the Atlantic Multidecadal Oscillation(AMO)reaches the maximum when the former leads the latter by 5–7 years.This seems to disagree with a previous well-realized point that the AMO modulates the decadal variation of EATs,since the atmosphere responds swiftly to sea surface temperature anomalies(SSTA)if therein.It implies that the AMO-EATs correlation should reach the maximum when they are simultaneous or the AMO leads EATs slightly,rather than that the EATs lead the AMO.Thus,this poses an issue about the reality of the newly found lead-lag correlation.Because the instrumental record in the natural climate system may be contaminated by human activities,the EATs-AMO lead-lag correlation derived from the instrumental records may not be a realistic connection of the natural climate system.Thus,whether the connection also exists in the proxies prior to the industrial is essential to answer the issue.In this study the EATs-AMO lead-lag connection is analyzed by using the reconstructed data in the last 500 years,together with the control experimental data with the prescribed pre-industrial forcing in a multiple of coupled climate system models,which attend the international CMIP5 program.The results suggest that the connection,the EATs lead the AMO,also exists in the period from the Little Ice Age(LIA)to the industrial,1500–1860AD.Therefore,the connection may be realistic in the natural climate system.The mechanisms for the connection are then discussed briefly.The results from this paper provide some insights into the connection of the AMO with East Asian climate.