The Flexible Global Ocean-Atmosphere-Land System model, Spectral Version 2 （FGOALS-s2） was used to simulate realistic climates and to study anthropogenic influences on climate change. Specifically, the FGOALS-s2 was...The Flexible Global Ocean-Atmosphere-Land System model, Spectral Version 2 （FGOALS-s2） was used to simulate realistic climates and to study anthropogenic influences on climate change. Specifically, the FGOALS-s2 was integrated with Coupled Model Intercomparison Project Phase 5 （CMIP5） to conduct co- ordinated experiments that will provide valuable scientific information to climate research communities. The performances of FGOALS-s2 were assessed in simulating major climate phenomena, and documented both the strengths and weaknesses of the model. The results indicate that FGOALS-s2 successfully overcomes climate drift, and realistically models global and regional climate characteristics, including SST, precipita- tion, and atmospheric circulation. In particular, the model accurately captures annual and semi-annual SST cycles in the equatorial Pacific Ocean, and the main characteristic features of the Asian summer monsoon, which include a low-level southwestern jet and five monsoon rainfall centers. The simulated climate variabil- ity was further examined in terms of teleconnections, leading modes of global SST （namely, ENSO）, Pacific Decadal Oscillations （PDO）, and changes in 19th-20th century climate. The analysis demonstrates that FGOALS-s2 realistically simulates extra-tropical teleconnection patterns of large-scale climate, and irregu- lar ENSO periods. The model gives fairly reasonable reconstructions of spatial patterns of PDO and global monsoon changes in the 20th century. However, because the indirect effects of aerosols are not included in the model, the simulated global temperature change during the period 1850 2005 is greater than the observed warming, by 0.6℃. Some other shortcomings of the model are also noted.展开更多
In order to assess the performance of two versions of the IAP/LASG Flexible Global Ocean-Atmosphere- Land System （FGOALS） model, simulated changes in surface air temperature （SAT）, from natural and an- thropogenie...In order to assess the performance of two versions of the IAP/LASG Flexible Global Ocean-Atmosphere- Land System （FGOALS） model, simulated changes in surface air temperature （SAT）, from natural and an- thropogenie forcings, were compared to observations for the period 1850-2005 at global, hemispheric, conti- nental and regional scales. The global and hemispheric averages of SAT and their land and ocean components during 1850-2005 were well reproduced by FGOALS-g2, as evidenced by significant correlation coefficients and small RMSEs. The significant positive correlations were firstly determined by the warming trends, and secondly by interdecadal fluctuations. The abilities of the models to reproduce interdecadal SAT variations were demonstrated by both wavelet analysis and significant positive correlations for detrended data. The observed land-sea thermal contrast change was poorly simulated. The major weakness of FGOALS-s2 was an exaggerated warming response to anthropogenic forcing, with the simulation showing results that were far removed from observations prior to the 1950s. The observations featured warming trends （1906-2005） of 0.71, 0.68 and 0.79℃ （100 yr）-1 for global, Northern and Southern Hemispheric averages, which were overestimated by FGOALS-s2 [1.42, 1.52 and 1.13~C （100 yr）-1] but underestimated by FGOALS-g2 [0.69, 0.68 and 0.73~C （100 yr）-l]. The polar amplification of the warming trend was exaggerated in FGOALS- s2 but weakly reproduced in FGOALS-g2. The stronger response of FGOALS-s2 to anthropogenic forcing was caused by strong sea-ice albedo feedback and water vapor feedback. Examination of model results in 15 selected subcontinental-scale regions showed reasonable performance for FGOALS-g2 over most regions. However, the observed warming trends were overestimated by FGOALS-s2 in most regions. Over East Asia, the meridional gradient of the warming trend simulated by FGOALS-s2 （FGOALS-g2） was stronger （weaker） than observed.展开更多
Climate drift in preindustrial control （PICTL） simulations can lead to spurious climate trends and large uncertainties in historical and future climate simulations in coupled models. This study examined the long- te...Climate drift in preindustrial control （PICTL） simulations can lead to spurious climate trends and large uncertainties in historical and future climate simulations in coupled models. This study examined the long- term behaviors and stabilities of the PICTL simulations in the two versions of FGOALS2 （the Flexible Global Ocean-Atmosphere-Land System model Version 2）, which have been submitted to the Coupled Model Inter- comparison Project Phase 5 （CMIP5）. As verified by examining time series of thermal fields and their linear trends, the PICTL simulations showed stable long-term integration behaviors and no obvious climate drift [the magnitudes of linear trends of SST were both less than 0.04℃ （100 yr）-1] over multiple centuries. The changed SSTs in a century （that corresponded to the linear trends） were less than the standard deviations of annual mean values, which implied the internal variability was not affected. These trend values were less than 10~0 of those of global averaged SST from observations and historical runs during the periods of slow and rapid warming. Such stable long-term integration behaviors reduced the uncertainty of the estimation of global warming rates in the historical and future climate projections in the two versions of FGOALS2. Compared with the trends in the Northern Hemisphere, larger trends existed in the SST and sea ice extents at the middle to high latitudes of the Southern Hemisphere （SH）. To estimate the historical and future climate trends in the SH or at some specific regions in FGOALS2, corrections needed to be carried out. The similar long-term behaviors in the two versions of FGOALS2 may be attributed to proper physical processes in the ocean model.展开更多
Responses of the East Asian winter monsoon （EAWM） in future projections were studied based on two core future projections of CMIP5 in coordinated experiments with the IAP-coupled model FGOALS2-s. The projected chang...Responses of the East Asian winter monsoon （EAWM） in future projections were studied based on two core future projections of CMIP5 in coordinated experiments with the IAP-coupled model FGOALS2-s. The projected changes of EAWM in climatology, seasonality, and interannual variability are reported here; the projections indicated strong warming in winter season. Warming increased with latitude, ranging from 1°C to 3°C in the Representative Concentration Pathways simulation RCP4.5 projection （an experiment that results in additional radiative forcing of 4.5 W m-2 in 2100） and from 4° to 9°C in the RCP8.5 projection （an experiment that results in additional radiative forcing of8.5 W m-2 in 2100）. The northerly wind along the East Asian coastal region became stronger in both scenarios, indicating a stronger EAWM. Accordingly, interannual variability （described by the standard deviation of temperature） increased around the South China Sea and lower latitudes and decreased over eastern China, especially in North China. The two EAWM basic modes, defined by the temperature EOF analysis over East Asia, were associated with the Arctic Oscillation （AO） and stratospheric polar vortex. The future projections revealed more total variance attributable to the secondary mode, suggesting additional influences from the stratosphere. The correlation between AO and the leading mode decreased, while the correlation between AO and the secondary mode increased, implying increased complexity regarding the predictability of EAWM interannual variations in future projections.展开更多
We describe the long-term stability and mean climatology of oceanic circulations simulated by version 2 of the Flexible Global Ocean-Atmosphere-Land System model （FGOALS-s2）. Driven by pre-industrial forcing, the in...We describe the long-term stability and mean climatology of oceanic circulations simulated by version 2 of the Flexible Global Ocean-Atmosphere-Land System model （FGOALS-s2）. Driven by pre-industrial forcing, the integration of FGOALS-s2 was found to have remained stable, with no obvious climate drift over 600 model years. The linear trends of sea SST and sea surface salinity （SSS） were -0.04℃ （100 yr）-1 and 0.01 psu （100 yr）-1, respectively. The simulations of oceanic temperatures, wind-driven circulation and thermohaline circulation in FGOALS-s2 were found to be comparable with observations, and have been substantially improved over previous FGOALS-s versions （1.0 and 1.1）. However, significant SST biases （exceeding 3℃） were found around strong western boundary currents, in the East China Sea, the Sea of Japan and the Barents Sea. Along the eastern coasts in the Pacific and Atlantic Ocean, a warm bias （〉3℃） was mainly due to overestimation of net surface shortwave radiation and weak oceanic upwelling. The difference of SST biases in the North Atlantic and Pacific was partly due to the errors of meridional heat transport. For SSS, biases exceeding 1.5 psu were located in the Arctic Ocean and around the Gulf Stream. In the tropics, freshwater biases dominated and were mainly caused by the excess of precipitation. Regarding the vertical dimension, the maximal biases of temperature and salinity were located north of 65°N at depths of greater than 600 m, and their values exceeded 4℃ and 2 psu, respectively.展开更多
Climate system models are useful tools for understanding the interactions among the components of the climate system and predicting/projecting future climate change. The development of climate models has been a centra...Climate system models are useful tools for understanding the interactions among the components of the climate system and predicting/projecting future climate change. The development of climate models has been a central focus of the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences(LASG/IAP) since the establishment of the laboratory in 1985. In China, many pioneering component models and fully coupled models of the climate system have been developed by LASG/IAP. The fully coupled climate system developed in the recent decade is named FGOALS(Flexible Global Ocean-Atmosphere-Land System Model). In this paper, an application-oriented review of the LASG/IAP FGOALS model is presented. The improved model performances are demonstrated in the context of cloud-radiation processes, Asian monsoon, ENSO phenomena, Atlantic Meridional Overturning Circulation(AMOC) and sea ice. The FGOALS model has contributed to both CMIP5(Coupled Model Intercomparison Project-phase 5) and IPCC(Intergovernmental Panel on Climate Change) AR5(the Fifth Assessment Report). The release of FGOALS data has supported the publication of nearly 500 papers around the world. The results of FGOALS are cited ~106 times in the IPCC WG1(Working Group 1) AR5. In addition to the traditional long-term simulations and projections, near-term decadal climate prediction is a new set of CMIP experiment, progress of LAGS/IAP in the development of nearterm decadal prediction system is reviewed. The FGOALS model has supported many Chinese national-level research projects and contributed to the national climate change assessment report. The crucial role of FGOALS as a modeling tool for supporting climate sciences is highlighted by demonstrating the model's performances in the simulation of the evolution of Earth's climate from the past to the future.展开更多
Net primary production （NPP） of crop represents the capacity of sequestrating atmospheric CO2 in agro-ecosystem, and it plays an important role in terrestrial carbon cycling. By linking the Crop-C model with climate...Net primary production （NPP） of crop represents the capacity of sequestrating atmospheric CO2 in agro-ecosystem, and it plays an important role in terrestrial carbon cycling. By linking the Crop-C model with climate change scenario projected by a coupled GCM FGOALS via geographical information system （GIS） techniques, crop NPP in China was simulated from 2000 to 2050. The national averaged surface air temperature from FGOALS is projected to increase by 1.0℃ over this period and the corresponding atmospheric CO2 concentration is 535 ppm by 2050 under the IPCC A1B scenario. With a spatial resolution of 10 ×10 km^2, model simulation indicated that an annual average increase of 0.6 Tg C yr^-1 （Tg=10^12 g） would be possible under the A1B scenario. The NPP in the late 2040s would increase by 5% （30 Tg C） within the 98×10^6 hm^2 cropland area in contrast with that in the early 2000s. A further investigation suggested that changes in the NPP would not be evenly distributed in China. A higher increase would occur in a majority of regions located in eastern and northwestern China, while a slight reduction would appear in Hebei and Tianjin in northern China. The spatial characteristics of the crop NPP change are attributed primarily to the uneven distribution of temperature change.展开更多
Paleoclimate simulations of the mid-Holocene （MH） and Last Glacial maximum （LGM） by the latest versions of the Flexible Global Ocean-Atmosphere-Land System model, Spectral Version 2 and Grid-point Version 2 （FGOA...Paleoclimate simulations of the mid-Holocene （MH） and Last Glacial maximum （LGM） by the latest versions of the Flexible Global Ocean-Atmosphere-Land System model, Spectral Version 2 and Grid-point Version 2 （FGOALS-s2 and g2） are evaluated in this study. The MH is characterized by changes of insolation induced by orbital parameters, and the LGM is a glacial period with large changes in greenhouse gases, sea level and ice sheets. For the MH, both versions of FGOALS simulate reasonable responses to the changes of insolation, such as the enhanced summer monsoon in African-Asian regions. Model differences can be identified at regional and seasonal scales. The global annual mean surface air temperature （TAS） shows no significant change in FGOALS-s2, while FGOALS-g2 shows a global cooling of about 0.7~C that is related with a strong cooling during boreal winter. The amplitude of ENSO is weaker in FGOALS-g2, which agrees with proxy data. For the LGM, FGOALS-g2 captures the features of the cold and dry glacial climate, including a global cooling of 4.6℃ and a decrease in precipitation by 10%. The ENSO is weaker at the LGM, with a tendency of stronger ENSO cold events. Sensitivity analysis shows that the Equilibrium Climate Sensitivity （ECS） estimated for FGOALS ranges between 4.23℃ and 4.59℃. The sensitivity of precipitation to the changes of TAS is -2.3%℃-1, which agrees with previous studies. FGOALS-g2 shows better simulations of the Atlantic Meridional Overturning Circulation （AMOC） and African summer monsoon precipitation in the MH when compared with FGOALS-gl.0; however, it is hard to conclude any improvements for the LGM.展开更多
To reveal the steric sea level change in 20th century historical climate simulations and future climate change projections under the IPCC＇s Representative Concentration Pathway 8.5 （RCP8.5） scenario, the results of...To reveal the steric sea level change in 20th century historical climate simulations and future climate change projections under the IPCC＇s Representative Concentration Pathway 8.5 （RCP8.5） scenario, the results of two versions of LASG/IAP＇s Flexible Global Ocean-Atmosphere-Land System model （FGOALS） are analyzed. Both models reasonably reproduce the mean dynamic sea level features, with a spatial pattern correlation coefficient of 0.97 with the observation. Characteristics of steric sea level changes in the 20th century historical climate simulations and RCPS.5 scenario projections are investigated. The results show that, in the 20th century, negative trends covered most parts of the global ocean. Under the RCPS.5 scenario, global-averaged steric sea level exhibits a pronounced rising trend throughout the 21st century and the general rising trend appears in most parts of the global ocean. The magnitude of the changes in the 21st century is much larger than that in the 20th century. By the year 2100, the global-averaged steric sea level anomaly is 18 cm and 10 cm relative to the year 1850 in the second spectral version of FGOALS （FGOALS-s2） and the second grid-point version of FGOALS （FGOALS-g2）, respectively. The separate contribution of the thermosteric and halosteric components from various ocean layers is further evaluated. In the 20th century, the steric sea level changes in FGOALS-s2 （FGOALS-g2） are largely attributed to the thermosteric （halosteric） component relative to the pre-industrial control run. In contrast, in the 21st century, the thermosteric component, mainly from the upper 1000 m, dominates the steric sea level change in both models under the RCPS.5 scenario. In addition, the steric sea level change in the marginal sea of China is attributed to the thermosteric component.展开更多
Changes of the net ocean surface heat flux（Q_（net）） into the tropical Indian Ocean（TIO） may be an indicator of the climate changes in the Asia and Indian–Pacific Ocean regions with the steadily warming trend in...Changes of the net ocean surface heat flux（Q_（net）） into the tropical Indian Ocean（TIO） may be an indicator of the climate changes in the Asia and Indian–Pacific Ocean regions with the steadily warming trend in the TIO since the 1950 s. Using two observational ocean surface flux products,this letter evaluates the historical simulations of Q_（net） over the TIO during 1984–2005 in two versions of FGOALS, from CMIP5. The results show that both models present a basin-wide underestimation of net surface heat flux, possibly resulting from the positive latent heat flux biases extending over almost the entire TIO basin. Both models share an Indian Ocean dipole-like bias in the net surface heat flux, consistent with precipitation, SST, and subsurface ocean temperature biases, which can be traced to errors in the South Asian summer monsoon. Area-averaged annual time series analyses of the surface heat budget imply that the FGOALS-s2 bias lies more in radiative imbalance, illustrating the need to improve cloud simulation; while the FGOALS-g2 bias presents ocean surface turbulence flux as the key process, requiring improvement in the simulation of oceanic processes. Neither FGOALS-g2 nor FGOALS-s2 can capture the decreasing tendency of Q_（net） well. All observed and simulated datasets imply surface latent heat flux as the primary contributing component, indicating the simulation biases of models may derive mainly from the biases in simulating latent heat flux. A small latent heat flux increase in models can be considered to be slowed by relaxed wind, increased stability, and surface relative humidity.展开更多
The major features of the westerly jets in boreal winter, consisting of the Middle East jet stream （MEJS）, East Asian jet stream （EAJS） and North Atlantic jet stream （NAJS）, simulated by a newly developed climat...The major features of the westerly jets in boreal winter, consisting of the Middle East jet stream （MEJS）, East Asian jet stream （EAJS） and North Atlantic jet stream （NAJS）, simulated by a newly developed climate system model, were evaluated with an emphasis on the meridional location of the westerly jet axis （WJA）. The model was found to exhibit fairly good performance in simulating the EAJS and NAJS, whereas the MEJS was much weaker and indistinguishable in the model. Compared with the intensity bias, the southward shift of the WJA seems to be a more remarkable deficiency. From the perspective of Ertel potential vorticity, the profiles along different westerly jet cores in the model were similar with those in the reanalysis but all shifted southward, indicating an equatorward displacement of the dynamic tropopause and associated climatology. Diagnosis of the thermodynamic equation revealed that the model produced an overall stronger heating source and the streamfunction quantifying the convection and overturning Hadley circulation shifted southward significantly in the middle and upper troposphere. The two maximum centers of eddy kinetic energy, corresponding to the EAJS and NAJS, were reproduced, whereas they all shifted southwards with a much reduced intensity. A lack of transient eddy activity will reduce the efficiency of poleward heat transport, which may partially contribute to the meridionally non-uniform cooling in the middle and upper troposphere. As the WJA is closely related to the location of the Hadley cell, tropopause and transient eddy activity, the accurate simulation of westerly jets will greatly improve the atmospheric general circulation and associated climatology in the model.展开更多
基金supported by"973"programs(Grant Nos.2012CB417203,2013CB955803 and 2010CB950404)"863"program(Grant No.2010AA012305)+1 种基金CAS Strategic Priority Research Program(Grant No.XDA05110303),the National Natural Science Foundation of China(Grant Nos.41023002and40805038)
文摘The Flexible Global Ocean-Atmosphere-Land System model, Spectral Version 2 （FGOALS-s2） was used to simulate realistic climates and to study anthropogenic influences on climate change. Specifically, the FGOALS-s2 was integrated with Coupled Model Intercomparison Project Phase 5 （CMIP5） to conduct co- ordinated experiments that will provide valuable scientific information to climate research communities. The performances of FGOALS-s2 were assessed in simulating major climate phenomena, and documented both the strengths and weaknesses of the model. The results indicate that FGOALS-s2 successfully overcomes climate drift, and realistically models global and regional climate characteristics, including SST, precipita- tion, and atmospheric circulation. In particular, the model accurately captures annual and semi-annual SST cycles in the equatorial Pacific Ocean, and the main characteristic features of the Asian summer monsoon, which include a low-level southwestern jet and five monsoon rainfall centers. The simulated climate variabil- ity was further examined in terms of teleconnections, leading modes of global SST （namely, ENSO）, Pacific Decadal Oscillations （PDO）, and changes in 19th-20th century climate. The analysis demonstrates that FGOALS-s2 realistically simulates extra-tropical teleconnection patterns of large-scale climate, and irregu- lar ENSO periods. The model gives fairly reasonable reconstructions of spatial patterns of PDO and global monsoon changes in the 20th century. However, because the indirect effects of aerosols are not included in the model, the simulated global temperature change during the period 1850 2005 is greater than the observed warming, by 0.6℃. Some other shortcomings of the model are also noted.
基金supported by the National High Technology Research and Development Program of China(Grant No.2010AA012304)National Program on Key Basic Research Project of China(Grant No.2010CB951904)NSFC project(Grant No.41125017)
文摘In order to assess the performance of two versions of the IAP/LASG Flexible Global Ocean-Atmosphere- Land System （FGOALS） model, simulated changes in surface air temperature （SAT）, from natural and an- thropogenie forcings, were compared to observations for the period 1850-2005 at global, hemispheric, conti- nental and regional scales. The global and hemispheric averages of SAT and their land and ocean components during 1850-2005 were well reproduced by FGOALS-g2, as evidenced by significant correlation coefficients and small RMSEs. The significant positive correlations were firstly determined by the warming trends, and secondly by interdecadal fluctuations. The abilities of the models to reproduce interdecadal SAT variations were demonstrated by both wavelet analysis and significant positive correlations for detrended data. The observed land-sea thermal contrast change was poorly simulated. The major weakness of FGOALS-s2 was an exaggerated warming response to anthropogenic forcing, with the simulation showing results that were far removed from observations prior to the 1950s. The observations featured warming trends （1906-2005） of 0.71, 0.68 and 0.79℃ （100 yr）-1 for global, Northern and Southern Hemispheric averages, which were overestimated by FGOALS-s2 [1.42, 1.52 and 1.13~C （100 yr）-1] but underestimated by FGOALS-g2 [0.69, 0.68 and 0.73~C （100 yr）-l]. The polar amplification of the warming trend was exaggerated in FGOALS- s2 but weakly reproduced in FGOALS-g2. The stronger response of FGOALS-s2 to anthropogenic forcing was caused by strong sea-ice albedo feedback and water vapor feedback. Examination of model results in 15 selected subcontinental-scale regions showed reasonable performance for FGOALS-g2 over most regions. However, the observed warming trends were overestimated by FGOALS-s2 in most regions. Over East Asia, the meridional gradient of the warming trend simulated by FGOALS-s2 （FGOALS-g2） was stronger （weaker） than observed.
基金supported by the National Key Program for Developing Basic Sciences(Grant Nos.2010CB950502 and 2013CB956204)the"Strategic Priority Research Program-Climate Change:Carbon Budget and Related Issues"of the Chinese Academy of Sciences(Grant No.XDA05110302)the National Natural Science Foundation of China(Grant Nos.40906012 and 41023002)
文摘Climate drift in preindustrial control （PICTL） simulations can lead to spurious climate trends and large uncertainties in historical and future climate simulations in coupled models. This study examined the long- term behaviors and stabilities of the PICTL simulations in the two versions of FGOALS2 （the Flexible Global Ocean-Atmosphere-Land System model Version 2）, which have been submitted to the Coupled Model Inter- comparison Project Phase 5 （CMIP5）. As verified by examining time series of thermal fields and their linear trends, the PICTL simulations showed stable long-term integration behaviors and no obvious climate drift [the magnitudes of linear trends of SST were both less than 0.04℃ （100 yr）-1] over multiple centuries. The changed SSTs in a century （that corresponded to the linear trends） were less than the standard deviations of annual mean values, which implied the internal variability was not affected. These trend values were less than 10~0 of those of global averaged SST from observations and historical runs during the periods of slow and rapid warming. Such stable long-term integration behaviors reduced the uncertainty of the estimation of global warming rates in the historical and future climate projections in the two versions of FGOALS2. Compared with the trends in the Northern Hemisphere, larger trends existed in the SST and sea ice extents at the middle to high latitudes of the Southern Hemisphere （SH）. To estimate the historical and future climate trends in the SH or at some specific regions in FGOALS2, corrections needed to be carried out. The similar long-term behaviors in the two versions of FGOALS2 may be attributed to proper physical processes in the ocean model.
基金supported by the National Basic Research Program of China(973 Program)(Grant Nos.2010CB428603 and 2012CB417203)the National Natural Science Foundation of China (Grant No.41175041)
文摘Responses of the East Asian winter monsoon （EAWM） in future projections were studied based on two core future projections of CMIP5 in coordinated experiments with the IAP-coupled model FGOALS2-s. The projected changes of EAWM in climatology, seasonality, and interannual variability are reported here; the projections indicated strong warming in winter season. Warming increased with latitude, ranging from 1°C to 3°C in the Representative Concentration Pathways simulation RCP4.5 projection （an experiment that results in additional radiative forcing of 4.5 W m-2 in 2100） and from 4° to 9°C in the RCP8.5 projection （an experiment that results in additional radiative forcing of8.5 W m-2 in 2100）. The northerly wind along the East Asian coastal region became stronger in both scenarios, indicating a stronger EAWM. Accordingly, interannual variability （described by the standard deviation of temperature） increased around the South China Sea and lower latitudes and decreased over eastern China, especially in North China. The two EAWM basic modes, defined by the temperature EOF analysis over East Asia, were associated with the Arctic Oscillation （AO） and stratospheric polar vortex. The future projections revealed more total variance attributable to the secondary mode, suggesting additional influences from the stratosphere. The correlation between AO and the leading mode decreased, while the correlation between AO and the secondary mode increased, implying increased complexity regarding the predictability of EAWM interannual variations in future projections.
基金supported by the National Key Program for Developing Basic Sciences(GrantNos. 2010CB950502)the "Strategic Priority Research Program-Climate Change:Carbon Budget and Related Issues" of the Chinese Academy of Sciences (Grant No.XDA05110302)+1 种基金the National Natural Science Foundation of China(Grant Nos. 40906012 and 41023002)National High Technology Research and Development Program of China(Grant No. 2010AA012303)
文摘We describe the long-term stability and mean climatology of oceanic circulations simulated by version 2 of the Flexible Global Ocean-Atmosphere-Land System model （FGOALS-s2）. Driven by pre-industrial forcing, the integration of FGOALS-s2 was found to have remained stable, with no obvious climate drift over 600 model years. The linear trends of sea SST and sea surface salinity （SSS） were -0.04℃ （100 yr）-1 and 0.01 psu （100 yr）-1, respectively. The simulations of oceanic temperatures, wind-driven circulation and thermohaline circulation in FGOALS-s2 were found to be comparable with observations, and have been substantially improved over previous FGOALS-s versions （1.0 and 1.1）. However, significant SST biases （exceeding 3℃） were found around strong western boundary currents, in the East China Sea, the Sea of Japan and the Barents Sea. Along the eastern coasts in the Pacific and Atlantic Ocean, a warm bias （〉3℃） was mainly due to overestimation of net surface shortwave radiation and weak oceanic upwelling. The difference of SST biases in the North Atlantic and Pacific was partly due to the errors of meridional heat transport. For SSS, biases exceeding 1.5 psu were located in the Arctic Ocean and around the Gulf Stream. In the tropics, freshwater biases dominated and were mainly caused by the excess of precipitation. Regarding the vertical dimension, the maximal biases of temperature and salinity were located north of 65°N at depths of greater than 600 m, and their values exceeded 4℃ and 2 psu, respectively.
基金supported by the National Natural Science Foundation of China (Grant No. 41330423, 41420104006 & 41530426 )the International Partnership Program of Chinese Academy of Sciences under Grant No.134111KYSB20160031
文摘Climate system models are useful tools for understanding the interactions among the components of the climate system and predicting/projecting future climate change. The development of climate models has been a central focus of the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences(LASG/IAP) since the establishment of the laboratory in 1985. In China, many pioneering component models and fully coupled models of the climate system have been developed by LASG/IAP. The fully coupled climate system developed in the recent decade is named FGOALS(Flexible Global Ocean-Atmosphere-Land System Model). In this paper, an application-oriented review of the LASG/IAP FGOALS model is presented. The improved model performances are demonstrated in the context of cloud-radiation processes, Asian monsoon, ENSO phenomena, Atlantic Meridional Overturning Circulation(AMOC) and sea ice. The FGOALS model has contributed to both CMIP5(Coupled Model Intercomparison Project-phase 5) and IPCC(Intergovernmental Panel on Climate Change) AR5(the Fifth Assessment Report). The release of FGOALS data has supported the publication of nearly 500 papers around the world. The results of FGOALS are cited ~106 times in the IPCC WG1(Working Group 1) AR5. In addition to the traditional long-term simulations and projections, near-term decadal climate prediction is a new set of CMIP experiment, progress of LAGS/IAP in the development of nearterm decadal prediction system is reviewed. The FGOALS model has supported many Chinese national-level research projects and contributed to the national climate change assessment report. The crucial role of FGOALS as a modeling tool for supporting climate sciences is highlighted by demonstrating the model's performances in the simulation of the evolution of Earth's climate from the past to the future.
文摘Net primary production （NPP） of crop represents the capacity of sequestrating atmospheric CO2 in agro-ecosystem, and it plays an important role in terrestrial carbon cycling. By linking the Crop-C model with climate change scenario projected by a coupled GCM FGOALS via geographical information system （GIS） techniques, crop NPP in China was simulated from 2000 to 2050. The national averaged surface air temperature from FGOALS is projected to increase by 1.0℃ over this period and the corresponding atmospheric CO2 concentration is 535 ppm by 2050 under the IPCC A1B scenario. With a spatial resolution of 10 ×10 km^2, model simulation indicated that an annual average increase of 0.6 Tg C yr^-1 （Tg=10^12 g） would be possible under the A1B scenario. The NPP in the late 2040s would increase by 5% （30 Tg C） within the 98×10^6 hm^2 cropland area in contrast with that in the early 2000s. A further investigation suggested that changes in the NPP would not be evenly distributed in China. A higher increase would occur in a majority of regions located in eastern and northwestern China, while a slight reduction would appear in Hebei and Tianjin in northern China. The spatial characteristics of the crop NPP change are attributed primarily to the uneven distribution of temperature change.
基金supported by the Chinese National Basic Research Program(Grant Nos.2010CB950502 and 2012CB955202)the "Strategic Priority Research Program Climate Change:Carbon Budget and Relevant Issues" of the Chinese Academy of Sciences(Grant No.XDA05110301)+2 种基金the National Natural Science Foundation of China(Grant Nos.41006008 and 41023002)the public science and technology research funds projects of meteorology(Grant No.GYHY200906020)the National Key Technologies R&D Program project(Grant No.2010AA012302)
文摘Paleoclimate simulations of the mid-Holocene （MH） and Last Glacial maximum （LGM） by the latest versions of the Flexible Global Ocean-Atmosphere-Land System model, Spectral Version 2 and Grid-point Version 2 （FGOALS-s2 and g2） are evaluated in this study. The MH is characterized by changes of insolation induced by orbital parameters, and the LGM is a glacial period with large changes in greenhouse gases, sea level and ice sheets. For the MH, both versions of FGOALS simulate reasonable responses to the changes of insolation, such as the enhanced summer monsoon in African-Asian regions. Model differences can be identified at regional and seasonal scales. The global annual mean surface air temperature （TAS） shows no significant change in FGOALS-s2, while FGOALS-g2 shows a global cooling of about 0.7~C that is related with a strong cooling during boreal winter. The amplitude of ENSO is weaker in FGOALS-g2, which agrees with proxy data. For the LGM, FGOALS-g2 captures the features of the cold and dry glacial climate, including a global cooling of 4.6℃ and a decrease in precipitation by 10%. The ENSO is weaker at the LGM, with a tendency of stronger ENSO cold events. Sensitivity analysis shows that the Equilibrium Climate Sensitivity （ECS） estimated for FGOALS ranges between 4.23℃ and 4.59℃. The sensitivity of precipitation to the changes of TAS is -2.3%℃-1, which agrees with previous studies. FGOALS-g2 shows better simulations of the Atlantic Meridional Overturning Circulation （AMOC） and African summer monsoon precipitation in the MH when compared with FGOALS-gl.0; however, it is hard to conclude any improvements for the LGM.
基金supported by the National High Technology Research and Development Program of China(863 Program)under Grant No.2010AA012304the"Strategic Priority Research Program-Climate Change:Carbon Budget and Related Issues"of the Chinese Academy of Sciences(Grant No.XDA05110301)the National Natural Science Foundation of China(Grant Nos.41125017 and 40890054)
文摘To reveal the steric sea level change in 20th century historical climate simulations and future climate change projections under the IPCC＇s Representative Concentration Pathway 8.5 （RCP8.5） scenario, the results of two versions of LASG/IAP＇s Flexible Global Ocean-Atmosphere-Land System model （FGOALS） are analyzed. Both models reasonably reproduce the mean dynamic sea level features, with a spatial pattern correlation coefficient of 0.97 with the observation. Characteristics of steric sea level changes in the 20th century historical climate simulations and RCPS.5 scenario projections are investigated. The results show that, in the 20th century, negative trends covered most parts of the global ocean. Under the RCPS.5 scenario, global-averaged steric sea level exhibits a pronounced rising trend throughout the 21st century and the general rising trend appears in most parts of the global ocean. The magnitude of the changes in the 21st century is much larger than that in the 20th century. By the year 2100, the global-averaged steric sea level anomaly is 18 cm and 10 cm relative to the year 1850 in the second spectral version of FGOALS （FGOALS-s2） and the second grid-point version of FGOALS （FGOALS-g2）, respectively. The separate contribution of the thermosteric and halosteric components from various ocean layers is further evaluated. In the 20th century, the steric sea level changes in FGOALS-s2 （FGOALS-g2） are largely attributed to the thermosteric （halosteric） component relative to the pre-industrial control run. In contrast, in the 21st century, the thermosteric component, mainly from the upper 1000 m, dominates the steric sea level change in both models under the RCPS.5 scenario. In addition, the steric sea level change in the marginal sea of China is attributed to the thermosteric component.
基金supported by the National Basic Research Program of China[grant number 2012CB417403]State Key Laboratory of Tropical Oceanography,South China Institute of Oceanology,Chinese Academy of Sciences[project number LTO1502]
文摘Changes of the net ocean surface heat flux（Q_（net）） into the tropical Indian Ocean（TIO） may be an indicator of the climate changes in the Asia and Indian–Pacific Ocean regions with the steadily warming trend in the TIO since the 1950 s. Using two observational ocean surface flux products,this letter evaluates the historical simulations of Q_（net） over the TIO during 1984–2005 in two versions of FGOALS, from CMIP5. The results show that both models present a basin-wide underestimation of net surface heat flux, possibly resulting from the positive latent heat flux biases extending over almost the entire TIO basin. Both models share an Indian Ocean dipole-like bias in the net surface heat flux, consistent with precipitation, SST, and subsurface ocean temperature biases, which can be traced to errors in the South Asian summer monsoon. Area-averaged annual time series analyses of the surface heat budget imply that the FGOALS-s2 bias lies more in radiative imbalance, illustrating the need to improve cloud simulation; while the FGOALS-g2 bias presents ocean surface turbulence flux as the key process, requiring improvement in the simulation of oceanic processes. Neither FGOALS-g2 nor FGOALS-s2 can capture the decreasing tendency of Q_（net） well. All observed and simulated datasets imply surface latent heat flux as the primary contributing component, indicating the simulation biases of models may derive mainly from the biases in simulating latent heat flux. A small latent heat flux increase in models can be considered to be slowed by relaxed wind, increased stability, and surface relative humidity.
基金supported by the National Natural Science Foundation of China(Grant Nos.41130963,41105044,and 41105045)the National Basic Research and Development(973)Program of China(Grant No.2012CB955901)the Research Fund for the Doctoral Program of Higher Education(Grant No.20100091110003)
文摘The major features of the westerly jets in boreal winter, consisting of the Middle East jet stream （MEJS）, East Asian jet stream （EAJS） and North Atlantic jet stream （NAJS）, simulated by a newly developed climate system model, were evaluated with an emphasis on the meridional location of the westerly jet axis （WJA）. The model was found to exhibit fairly good performance in simulating the EAJS and NAJS, whereas the MEJS was much weaker and indistinguishable in the model. Compared with the intensity bias, the southward shift of the WJA seems to be a more remarkable deficiency. From the perspective of Ertel potential vorticity, the profiles along different westerly jet cores in the model were similar with those in the reanalysis but all shifted southward, indicating an equatorward displacement of the dynamic tropopause and associated climatology. Diagnosis of the thermodynamic equation revealed that the model produced an overall stronger heating source and the streamfunction quantifying the convection and overturning Hadley circulation shifted southward significantly in the middle and upper troposphere. The two maximum centers of eddy kinetic energy, corresponding to the EAJS and NAJS, were reproduced, whereas they all shifted southwards with a much reduced intensity. A lack of transient eddy activity will reduce the efficiency of poleward heat transport, which may partially contribute to the meridionally non-uniform cooling in the middle and upper troposphere. As the WJA is closely related to the location of the Hadley cell, tropopause and transient eddy activity, the accurate simulation of westerly jets will greatly improve the atmospheric general circulation and associated climatology in the model.
