In recent decades,a greening tendency due to increased vegetation has been noted around the Taklimakan Desert(TD),but the impact of such a change on the local hydrological cycle remains uncertain.Here,we investigate t...In recent decades,a greening tendency due to increased vegetation has been noted around the Taklimakan Desert(TD),but the impact of such a change on the local hydrological cycle remains uncertain.Here,we investigate the response of the local hydrological cycle and atmospheric circulation to a green TD in summer using a pair of global climate model(Community Earth System Model version 1.2.1)simulations.With enough irrigation to support vegetation growth in the TD,the modeling suggests first,that significant increases in local precipitation are attributed to enhanced local recycling of water,and second,that there is a corresponding decrease of local surface temperatures.On the other hand,irrigation and vegetation growth in this low-lying desert have negligible impacts on the large-scale circulation and thus the moisture convergence for enhanced precipitation.It is also found that the green TD can only be sustained by a large amount of irrigation water supply since only about one-third of the deployed water can be“recycled”locally.Considering this,devising a way to encapsulate the irrigated water within the desert to ensure more efficient water recycling is key for maintaining a sustainable,greening TD.展开更多
A double-plume convective parameterization scheme is revised to improve the precipitation simulation of a global model(Global-to-Regional Integrated Forecast System;GRIST).The improvement is achieved by considering th...A double-plume convective parameterization scheme is revised to improve the precipitation simulation of a global model(Global-to-Regional Integrated Forecast System;GRIST).The improvement is achieved by considering the effects of large-scale dynamic processes on the trigger of deep convection.The closure,based on dynamic CAPE,is improved accordingly to allow other processes to consume CAPE under the more restricted convective trigger condition.The revised convective parameterization is evaluated with a variable-resolution model setup(110–35 km,refined over East Asia).The Atmospheric Model Intercomparison Project(AMIP)simulations demonstrate that the revised convective parameterization substantially delays the daytime precipitation peaks over most land areas,leading to an improved simulated diurnal cycle,evidenced by delayed and less frequent afternoon precipitation.Meanwhile,changes to the threshold of the trigger function yield a small impact on the diurnal amplitude of precipitation because of the consistent setting of dCAPE-based trigger and closure.The simulated mean precipitation remains reasonable,with some improvements evident along the southern slopes of the Tibetan Plateau.The revised scheme increases convective precipitation at the lower levels of the windward slope and reduces the large-scale precipitation over the upper slope,ultimately shifting the rainfall peak southward,which is in better agreement with the observations.展开更多
Background:Large uncertainty in modeling land carbon(C)uptake heavily impedes the accurate prediction of the global C budget.Identifying the uncertainty sources among models is crucial for model improvement yet has be...Background:Large uncertainty in modeling land carbon(C)uptake heavily impedes the accurate prediction of the global C budget.Identifying the uncertainty sources among models is crucial for model improvement yet has been difficult due to multiple feedbacks within Earth System Models(ESMs).Here we present a Matrix-based Ensemble Model Inter-comparison Platform(MEMIP)under a unified model traceability framework to evaluate multiple soil organic carbon(SOC)models.Using the MEMIP,we analyzed how the vertically resolved soil biogeochemistry structure influences SOC prediction in two soil organic matter(SOM)models.By comparing the model outputs from the C-only and CN modes,the SOC differences contributed by individual processes and N feedback between vegetation and soil were explicitly disentangled.Results:Results showed that the multi-layer models with a vertically resolved structure predicted significantly higher SOC than the single layer models over the historical simulation(1900–2000).The SOC difference between the multi-layer models was remarkably higher than between the single-layer models.Traceability analysis indicated that over 80%of the SOC increase in the multi-layer models was contributed by the incorporation of depth-related processes,while SOC differences were similarly contributed by the processes and N feedback between models with the same soil depth representation.Conclusions:The output suggested that feedback is a non-negligible contributor to the inter-model difference of SOC prediction,especially between models with similar process representation.Further analysis with TRENDY v7 and more extensive MEMIP outputs illustrated the potential important role of multi-layer structure to enlarge the current ensemble spread and the necessity of more detail model decomposition to fully disentangle inter-model differences.We stressed the importance of analyzing ensemble outputs from the fundamental model structures,and holding a holistic view in understanding the ensemble uncertainty.展开更多
Relatively little is known about the impact of global warming on the tropical cyclone(TC)outflow,despite its large contribution to TC intensity.In this study,based on the International Best Track Archive for Climate S...Relatively little is known about the impact of global warming on the tropical cyclone(TC)outflow,despite its large contribution to TC intensity.In this study,based on the International Best Track Archive for Climate Stewardship(IBTrACS)dataset and ERA5 reanalysis data,we show that the TC outflow height has risen significantly(48.20±22.18 m decades-1)in the past decades(1959-2021)over the western North Pacific,and the rising trend tends to be sharper for stronger TCs(the uptrend of severe typhoon is 61.09±40.92 m decades-1).This rising trend of the outflow height explains the contradiction between the decrease trend of the TC outflow temperature and the increase trend of the atmospheric troposphere temperature.Moreover,possible contribution of the TC outflow height uptrend to TC intensity has also been investigated.The results show that the rise of outflow height leads to the decrease of outflow temperature,and thus an increased difference between underlying sea surface temperature(SST)and TC outflow temperature,which eventually favors the increase of TC intensity.展开更多
The Earth–Climate System Model(ECSM)is an important platform for multi-disciplinary and multi-sphere integration research,and its development is at the frontier of international geosciences,especially in the field of...The Earth–Climate System Model(ECSM)is an important platform for multi-disciplinary and multi-sphere integration research,and its development is at the frontier of international geosciences,especially in the field of global change.The research and development(R&D)of ECSM in China began in the 1980 s and have achieved great progress.In China,ECSMs are now mainly developed at the Chinese Academy of Sciences,ministries,and universities.Following a brief review of the development history of Chinese ECSMs,this paper summarized the technical characteristics of nine Chinese ECSMs participating in the Coupled Model Intercomparison Project Phase 6 and preliminarily assessed the basic performances of four Chinese models in simulating the global climate and the climate in East Asia.The projected changes of global precipitation and surface air temperature and the associated relationship with the equilibrium climate sensitivity under four shared socioeconomic path scenarios were also discussed.Finally,combined with the international situation,from the perspective of further improvement,eight directions were proposed for the future development of Chinese ECSMs.展开更多
The Tibetan Plateau(TP)is considered to be the‘‘Third Pole”of the earth because of its huge area(5 million km2),its high elevation(>4000 m average altitude),and the presence of more than 100,000 km2 of glaciers ...The Tibetan Plateau(TP)is considered to be the‘‘Third Pole”of the earth because of its huge area(5 million km2),its high elevation(>4000 m average altitude),and the presence of more than 100,000 km2 of glaciers in this northern mid-latitude region.As a result of these factors,the TP influences both short-term regional and large-scale atmospheric circulation and long-term climate change[1].More than ten large rivers originate from the TP and constitute an essential water supply for nearly one sixth of the global population.Hence the TP is often referred to as‘‘the water tower of Asia”[1,2].Variations of summer rainfall over the TP greatly impact inland closed lakes,river discharge,glaciers,plant phenology,and natural hazards[2].展开更多
基金This work was supported by the National Key Research Project of China(Grant No.2018YFC 1507001).
文摘In recent decades,a greening tendency due to increased vegetation has been noted around the Taklimakan Desert(TD),but the impact of such a change on the local hydrological cycle remains uncertain.Here,we investigate the response of the local hydrological cycle and atmospheric circulation to a green TD in summer using a pair of global climate model(Community Earth System Model version 1.2.1)simulations.With enough irrigation to support vegetation growth in the TD,the modeling suggests first,that significant increases in local precipitation are attributed to enhanced local recycling of water,and second,that there is a corresponding decrease of local surface temperatures.On the other hand,irrigation and vegetation growth in this low-lying desert have negligible impacts on the large-scale circulation and thus the moisture convergence for enhanced precipitation.It is also found that the green TD can only be sustained by a large amount of irrigation water supply since only about one-third of the deployed water can be“recycled”locally.Considering this,devising a way to encapsulate the irrigated water within the desert to ensure more efficient water recycling is key for maintaining a sustainable,greening TD.
基金supported by the National Key R&D Program of China on the Monitoring,Early Warning,and Prevention of Major Natural Disasters(Grant Nos.2018YFC1507005 and 02017YFC1502202)。
文摘A double-plume convective parameterization scheme is revised to improve the precipitation simulation of a global model(Global-to-Regional Integrated Forecast System;GRIST).The improvement is achieved by considering the effects of large-scale dynamic processes on the trigger of deep convection.The closure,based on dynamic CAPE,is improved accordingly to allow other processes to consume CAPE under the more restricted convective trigger condition.The revised convective parameterization is evaluated with a variable-resolution model setup(110–35 km,refined over East Asia).The Atmospheric Model Intercomparison Project(AMIP)simulations demonstrate that the revised convective parameterization substantially delays the daytime precipitation peaks over most land areas,leading to an improved simulated diurnal cycle,evidenced by delayed and less frequent afternoon precipitation.Meanwhile,changes to the threshold of the trigger function yield a small impact on the diurnal amplitude of precipitation because of the consistent setting of dCAPE-based trigger and closure.The simulated mean precipitation remains reasonable,with some improvements evident along the southern slopes of the Tibetan Plateau.The revised scheme increases convective precipitation at the lower levels of the windward slope and reduces the large-scale precipitation over the upper slope,ultimately shifting the rainfall peak southward,which is in better agreement with the observations.
基金supported by the National Natural Science Foundation of China[grant Nos.42125503 and 42075137]the National Key Research and Development Program of China[grant Nos.2020YFA0608000 and 2020YFA0607900].
基金This study is supported by the funding from the National Key Research and Development Program of China under grants 2017YFA0604600YC was supported by National Youth Science Fund of China(41701227).DL is supported by the National Center for Atmospheric Research,which is a major facility sponsored by the National Science Foundation(NSF)under Cooperative Agreement 1852977.DL’s computing and data storage resources,including the Cheyenne supercomputer(https://doi.org/10.5065/D6RX99HX),were provided by the Computational and Information Systems Laboratory(CISL)at NCAR.DSG receives support from the ANR CLAND Convergence Institute.
文摘Background:Large uncertainty in modeling land carbon(C)uptake heavily impedes the accurate prediction of the global C budget.Identifying the uncertainty sources among models is crucial for model improvement yet has been difficult due to multiple feedbacks within Earth System Models(ESMs).Here we present a Matrix-based Ensemble Model Inter-comparison Platform(MEMIP)under a unified model traceability framework to evaluate multiple soil organic carbon(SOC)models.Using the MEMIP,we analyzed how the vertically resolved soil biogeochemistry structure influences SOC prediction in two soil organic matter(SOM)models.By comparing the model outputs from the C-only and CN modes,the SOC differences contributed by individual processes and N feedback between vegetation and soil were explicitly disentangled.Results:Results showed that the multi-layer models with a vertically resolved structure predicted significantly higher SOC than the single layer models over the historical simulation(1900–2000).The SOC difference between the multi-layer models was remarkably higher than between the single-layer models.Traceability analysis indicated that over 80%of the SOC increase in the multi-layer models was contributed by the incorporation of depth-related processes,while SOC differences were similarly contributed by the processes and N feedback between models with the same soil depth representation.Conclusions:The output suggested that feedback is a non-negligible contributor to the inter-model difference of SOC prediction,especially between models with similar process representation.Further analysis with TRENDY v7 and more extensive MEMIP outputs illustrated the potential important role of multi-layer structure to enlarge the current ensemble spread and the necessity of more detail model decomposition to fully disentangle inter-model differences.We stressed the importance of analyzing ensemble outputs from the fundamental model structures,and holding a holistic view in understanding the ensemble uncertainty.
基金Supported by the National Natural Science Foundation of China(42075035 and 42075011)。
文摘Relatively little is known about the impact of global warming on the tropical cyclone(TC)outflow,despite its large contribution to TC intensity.In this study,based on the International Best Track Archive for Climate Stewardship(IBTrACS)dataset and ERA5 reanalysis data,we show that the TC outflow height has risen significantly(48.20±22.18 m decades-1)in the past decades(1959-2021)over the western North Pacific,and the rising trend tends to be sharper for stronger TCs(the uptrend of severe typhoon is 61.09±40.92 m decades-1).This rising trend of the outflow height explains the contradiction between the decrease trend of the TC outflow temperature and the increase trend of the atmospheric troposphere temperature.Moreover,possible contribution of the TC outflow height uptrend to TC intensity has also been investigated.The results show that the rise of outflow height leads to the decrease of outflow temperature,and thus an increased difference between underlying sea surface temperature(SST)and TC outflow temperature,which eventually favors the increase of TC intensity.
基金Supported by the International Partnership Program of Chinese Academy of Sciences(134111KYSB20160031)National Natural Science Foundation of China(41875132).
文摘The Earth–Climate System Model(ECSM)is an important platform for multi-disciplinary and multi-sphere integration research,and its development is at the frontier of international geosciences,especially in the field of global change.The research and development(R&D)of ECSM in China began in the 1980 s and have achieved great progress.In China,ECSMs are now mainly developed at the Chinese Academy of Sciences,ministries,and universities.Following a brief review of the development history of Chinese ECSMs,this paper summarized the technical characteristics of nine Chinese ECSMs participating in the Coupled Model Intercomparison Project Phase 6 and preliminarily assessed the basic performances of four Chinese models in simulating the global climate and the climate in East Asia.The projected changes of global precipitation and surface air temperature and the associated relationship with the equilibrium climate sensitivity under four shared socioeconomic path scenarios were also discussed.Finally,combined with the international situation,from the perspective of further improvement,eight directions were proposed for the future development of Chinese ECSMs.
基金supported by the National Natural Science Foundation of China(41671006)
文摘The Tibetan Plateau(TP)is considered to be the‘‘Third Pole”of the earth because of its huge area(5 million km2),its high elevation(>4000 m average altitude),and the presence of more than 100,000 km2 of glaciers in this northern mid-latitude region.As a result of these factors,the TP influences both short-term regional and large-scale atmospheric circulation and long-term climate change[1].More than ten large rivers originate from the TP and constitute an essential water supply for nearly one sixth of the global population.Hence the TP is often referred to as‘‘the water tower of Asia”[1,2].Variations of summer rainfall over the TP greatly impact inland closed lakes,river discharge,glaciers,plant phenology,and natural hazards[2].
