CAS-ESM2.0 Dataset for the Carbon Dioxide Removal Model Intercomparison Project(CDRMIP)

Understanding the response of the Earth system to varying concentrations of carbon dioxide(CO_(2))is critical for projecting possible future climate change and for providing insight into mitigation and adaptation strategies in the near future.In this study,we generate a dataset by conducting an experiment involving carbon dioxide removal(CDR)—a potential way to suppress global warming—using the Chinese Academy of Sciences Earth System Model version 2.0(CASESM2.0).A preliminary evaluation is provided.The model is integrated from 200–340 years as a 1%yr^(−1) CO_(2) concentration increase experiment,and then to~478 years as a carbon dioxide removal experiment until CO_(2) returns to its original value.Finally,another 80 years is integrated in which CO_(2) is kept constant.Changes in the 2-m temperature,precipitation,sea surface temperature,ocean temperature,Atlantic meridional overturning circulation(AMOC),and sea surface height are all analyzed.In the ramp-up period,the global mean 2-m temperature and precipitation both increase while the AMOC weakens.Values of all the above variables change in the opposite direction in the ramp-down period,with a delayed peak relative to the CO_(2) peak.After CO_(2) returns to its original value,the global mean 2-m temperature is still~1 K higher than in the original state,and precipitation is~0.07 mm d^(–1) higher.At the end of the simulation,there is a~0.5°C increase in ocean temperature and a 1 Sv weakening of the AMOC.Our model simulation produces similar results to those of comparable experiments previously reported in the literature.

CAS-ESM2.0 Model Datasets for the CMIP6 Flux-Anomaly-Forced Model Intercomparison Project (FAFMIP)

The second version of the Chinese Academy of Sciences Earth System Model(CAS-ESM2.0)is participating in the Flux-Anomaly-Forced Model Intercomparison Project(FAFMIP)experiments in phase 6 of the Coupled Model Intercomparison Project(CMIP6).The purpose of FAFMIP is to understand and reduce the uncertainty of ocean climate changes in response to increased CO2 forcing in atmosphere-ocean general circulation models(AOGCMs),including the simulations of ocean heat content(OHC)change,ocean circulation change,and sea level rise due to thermal expansion.FAFMIP experiments(including faf-heat,faf-stress,faf-water,faf-all,faf-passiveheat,faf-heat-NA50pct and faf-heat-NA0pct)have been conducted.All of the experiments were integrated over a 70-year period and the corresponding data have been uploaded to the Earth System Grid Federation data server for CMIP6 users to download.This paper describes the experimental design and model datasets and evaluates the preliminary results of CAS-ESM2.0 simulations of ocean climate changes in the FAFMIP experiments.The simulations of the changes in global ocean temperature,Atlantic Meridional Overturning Circulation(AMOC),OHC,and dynamic sea level(DSL),are all reasonably reproduced.

Blooms of Prorocentrum donghaiense reduced the species diversity of dinoflagellate community

Most of reported harmful algal blooms(HABs)of microalgae(75%)have been caused by dinoflagellates.Studies on the negative effects of HABs have generally focused on animals,valuable organisms in particular,and environmental factors such as dissolved oxygen and nutrients,but relatively fewer on community level,particularly that using metagenomic approach.In this study,we reported an investigation on the effects of a HAB caused by the dinoflagellate Prorocentrum donghaiense on the species diversity and community structure of the dinoflagellate sub-community via a pyrosequencing approach for the samples taken before,during,and after the bloom season of P.donghaiense in the East China Sea.We sequenced partial 28S rRNA gene of dinoflagellates for the field samples and evaluated the species richness and diversity indices of the dinoflagellate community,as a sub-community of the total phytoplankton.We obtained 800185 valid sequences(categorized into 560 operational taxonomic units,OTUs)of dinoflagellates from 50 samples and found that the biodiversity of dinoflagellate community was significantly reduced during the blooming period in comparison to that in pre-and after-blooming periods,as reflected in the four diversity indices:the species richness expressed as the number of OTUs,Chao1 index,Shannon index(evenness),and Gini-Simpson index.These four indices were all found to be negatively correlated to the cell density of the bloom species P.donghaiense.Correlation analyses also revealed that the P.donghaiense cell abundance was correlated negatively with NO3--N,and NO2--N,but positively with total nitrogen(TN)and total phosphorus(TP).Principal coordinates analysis(PCoA)showed that the community structure of dinoflagellates was markedly different among the different sampling periods,while the redundancy analysis(RDA)revealed P.donghaiense abundance,salinity,NO3--N,and SiO32-were the most four significant factors shaping the dinoflagellate community structure.Our results together demonstrated that HABs caused by the dinoflagellate P.donghaiense could strongly impact the aquatic ecosystem on the sub-community level which the blooming species belongs to.

A high-top version of IAP-AGCM:Preliminary assessment and sensitivity IAP-AGCM

Extending the atmospheric model top to high altitude is important for simulation of upper atmospheric phenomena,such as the stratospheric quasi-biennial oscillation.The high-top version of the Institute of Atmospheric Physics Atmospheric General Circulation Model with 91 vertical layers(IAP-AGCML91)extends to the mesopause at about 0.01 hPa(~80 km).The high-top model with a fully resolved stratosphere is found to simulate a warmer stratosphere than the low-top version,except near the South Pole,thus reducing its overall cold bias in the stratosphere,and significantly in the upper stratosphere.This sensitivity is shown to be consistent with two separate mechanisms:larger shortwave heating and larger poleward stratospheric meridional eddy heat flux in the hightop model than in the low-top model.Results indicate a significant influence of vertical resolution and model top on climate simulations in IAP-AGCM.

China’s EarthLab-Forefront of Earth System Simulation Research

This article introduces“EarthLab”,a major new Earth system numerical simulation facility developed in China.EarthLab is a numerical simulation system for a physical climate system,an environmental system,an ecological system,a solid earth system,and a space weather system as a whole with a high-performance scientific computing platform.EarthLab consists of five key elements-namely:a global earth numerical simulation system,a regional high-precision simulation system,a supercomputing support and management system,a database,data assimilation and visualization system,and a high-performance computing system for earth sciences.EarthLab helps to study the atmosphere,hydrosphere,cryosphere,lithosphere,and biosphere,as well as their interactions,to improve the accuracy of predictions by integrating simulations and observations,and to provide a scientific foundation for major issues such as national disaster prevention and mitigation.The construction and operation of EarthLab will involve close cooperation with joint contributions and shared benefits.

Reviving and characterizing three species of dinoflagellate cysts dormant for about 70 years in the East China Sea:Biecheleria brevisulcata,Biecheleriopsis adriatica,and Scrippsiella donghaienis

Many marine dinoflagellates can form resting cysts as a part of their life cycle,and the cysts could be buried in sediment and remained viable for as long as over 150 years.However,only a very limited number of cyst species have been revived from long-buried sediments and investigated in regard to a possible shift in the intra-specific genetic structure of a species detected from the historical record at a particular location.Here,we report a successful germination of three species of resting cysts that were sampled from the depth dated back to 1941±18 AD from a 44-cm sediment core from the East China Sea.Seven isolates were established from germination of single cyst isolation or multi-cyst germinations.LSU rRNA gene or ITS sequences of these strains were obtained,then they were identified to be Biecheleria brevisulcata(five strains),Biecheleriopsis adriatica(one strain),and Scrippsiella donghaienis(one strain)in terms of morphology and rRNA gene sequence.Biecheleria brevisulcata strain 1,Bps.adriatica strain 21,and S.donghaienis strain 23 were examined in detail with light microscope(LM)and scanning electron microscope(SEM),and analyzed with high performance liquid chromatography(HPLC)for their pigment compositions,and genetic diversity.We also confirmed the presence of a resting cyst of Bps.adriatica in the field for the first time.The LSU rRNA gene-based genetic distances of Bps.adriatica from that obtained from water sample,single-cell PCR sequencing for the cysts isolated from the surface sediment of the same sea area and that reported from other regions during the recent years,and ITS-based genetic distances of S.donghaienis from that obtained from cysts isolated from the surface sediment of the same location and that reported from other regions during the recent years indicated that the intra-specific genetic structure of each species in the sampling area may have shifted during the last 70 years.Our work confirms that B.brevisulcata,Bps.adriatica,and S.donghaienis,all described as new species around 2010,have inhabited the East China Sea for about 70 years.The present work reports for the first time the revival of dinoflagellate resting cysts long-buried in the coastal sediments of China,which facilitates further study on the historical occurrences of other harmful dinoflagellates and their relevance to the regional climate and environmental changes in China.

Simulation of the QBO in IAP-AGCM:Analysis of momentum budget

The quasi-biennial oscillation(QBO),a dominant mode of the equatorial stratospheric(~100–1 hPa)variability,is known to impact tropospheric circulation in the middle and high latitudes.Yet,its realistic simulation in general circulation models remains a challenge.The authors examine the simulated QBO in the 69-layer version of the Institute of Atmospheric Physics Atmospheric General Circulation Model(IAP-AGCML69)and analyze its momentum budget.The authors find that the QBO is primarily caused by parameterized gravity-wave forcing due to tropospheric convection,but the downward propagation of the momentum source is significantly offset by the upward advection of zonal wind by the equatorial upwelling in the stratosphere.Resolved-scale waves act as a positive contribution to the total zonal wind tendency of the QBO over the equator with comparable magnitude to the gravity-wave forcing in the upper stratosphere.Results provide insights into the mechanism of the QBO and possible causes of differences in models.