Using the low-resolution (T31, equivalent to 3.75°× 3.75°) version of the Community Earth System Model (CESM) from the National Center for Atmospheric Research (NCAR), a global climate simulation ...Using the low-resolution (T31, equivalent to 3.75°× 3.75°) version of the Community Earth System Model (CESM) from the National Center for Atmospheric Research (NCAR), a global climate simulation was carried out with fixed external forcing factors (1850 Common Era. (C.E.) conditions) for the past 2000 years. Based on the simulated results, spatio-temporal structures of surface air temperature, precipitation and internal variability, such as the E1 Nifio-Southem Oscillation (ENSO), the Atlantic Multi-decadal Oscilla- tion (AMO), the Pacific Decadal Oscillation (PDO), and the North Atlantic Oscillation (NAO), were compared with reanalysis datasets to evaluate the model performance. The results are as follows: 1) CESM showed a good performance in the long-term simulation and no significant climate drift over the past 2000 years; 2) climatological patterns of global and regional climate changes simulated by the CESM were reasonable compared with the reanalysis datasets; and 3) the CESM simulated internal natural variability of the climate system performs very well. The model not only reproduced the periodicity of ENSO, AMO and PDO events but also the 3-8 years vari- ability of the ENSO. The spatial distribution of the CESM-simulated NAO was also similar to the observed. However, because of weaker total irradiation and greenhouse gas concentration forcing in the simulation than the present, the model performances had some differences from the observations. Generally, the CESM showed a good performance in simulating the global climate and internal natu- ral variability of the climate system. This paves the way for other forced climate simulations for the past 2000 years by using the CESM.展开更多
The Community Microwave Emission Model (CMEM) developed by the European Centre for Me-dium-Range Weather Forecasts (ECMWF) can provide a link between surface states and satellite observations and simulate the passive ...The Community Microwave Emission Model (CMEM) developed by the European Centre for Me-dium-Range Weather Forecasts (ECMWF) can provide a link between surface states and satellite observations and simulate the passive microwave brightness temperature of the surface at low frequencies (from 1 GHz to 20 GHz).This study evaluated the performance of the CMEM cou-pled with the Community Land Model (CLM) (CMEM-CLM) using C-band (6.9 GHz) microwave brightness temperatures from the Advanced Microwave Scanning Radiometer on Earth Observing System (AMSR-E) over East Asia.Preliminary results support the argument that the simulated brightness temperatures of CMEM-CLM from July 2005 to June 2010 are comparable to AMSR-E observational data.CMEM-CLM performed better for vertical polarization,for which the root mean square error was approximately 15 K,compared to over 30 K for horizontal polarization.An evaluation performed over seven sub-regions in China indicated that CMEM-CLM was able to capture the temporal evolution of C-band brightness temperatures well,and the best correlation with AMSR-E appeared over western Northwest China (over 0.9 for vertical polarization).However,larger biases were found over southern North China and the middle and lower reaches of the Yangtze River.展开更多
The influences of vegetation on intraseasonal oscillation (ISO) were examined using the Community Atmosphere Model version 3 (CAM3). Two 15-year numerical experiments were completed: the first was performed with ...The influences of vegetation on intraseasonal oscillation (ISO) were examined using the Community Atmosphere Model version 3 (CAM3). Two 15-year numerical experiments were completed: the first was performed with a realistic vegetation distribution (VEG run), and the second was identical to the VEG run except without land vegetation (NOVEG run). Generally speak- ing, CAM3 was able to reproduce the spatial distribution of the ISO, but the ISO intensity in the simulation was much weaker than that observed in nature: the 1SO has a relatively much stronger signal. A comparison of the VEG run with the NOVEG run revealed that the presence of vegetation usually produces a weak ISO. The vegetation effects on ISO intensity were significant over West Africa and South Asia, especially in the summer half-year. Vegetation also plays an important role in modulating ISO propagation. The eastward propagation of the ISO in the VEG run was clearer than that in the NOVEG run over the West African and Maritime Continent regions. The northward propagation of the ISO in the VEG run was more consistent with observation than that in the NOVEG run.展开更多
The capability of an improved Dynamic Global Vegetation Model (DGVM) in reproducing the impact of climate on the terrestrial ecosystem is evaluated. The new model incorporates the Community Land Model- DGVM (CLM3.0...The capability of an improved Dynamic Global Vegetation Model (DGVM) in reproducing the impact of climate on the terrestrial ecosystem is evaluated. The new model incorporates the Community Land Model- DGVM (CLM3.0-DGVM) with a submodel for temperate and boreal shrubs, as well as other revisions such as the "two-leaf" scheme for photosynthesis and the definition of fractional coverage of plant functional types (PFTs). Results show that the revised model may correctly reproduce the global distribution of temperate and boreal shrubs, and improves the model performance with more realistic distribution of di?erent vege- tation types. The revised model also correctly reproduces the zonal distributions of vegetation types. In reproducing the dependence of the vegetation distribution on climate conditions, the model shows that the dominant regions for trees, grasses, shrubs, and bare soil are clearly separated by a climate index derived from mean annual precipitation and temperature, in good agreement with the CLM4 surface data. The dominant plant functional type mapping to a two dimensional parameter space of mean annual temperature and precipitation also qualitatively agrees with the results from observations and theoretical ecology studies.展开更多
The choices of the parameterizations for each component in a microwave emission model have significant effects on the quality of brightness temperature (Tb) sim- ulation. How to reduce the uncertainty in the Tb simu...The choices of the parameterizations for each component in a microwave emission model have significant effects on the quality of brightness temperature (Tb) sim- ulation. How to reduce the uncertainty in the Tb simulation is investigated by adopting a statistical post-processing procedure with the Bayesian model averaging (BMA) ensemble approach. The simulations by the community microwave emission model (CMEM) cou- pled with the community land model version 4.5 (CLM4.5) over China's Mainland are con- ducted by the 24 configurations from four vegetation opacity parameterizations (VOPs), three soil dielectric constant parameterizations (SDCPs), and two soil roughness param- eterizations (SRPs). Compared with the simple arithmetical averaging (SAA) method, the BMA reconstructions have a higher spatial correlation coefficient (larger than 0.99) than the C-band satellite observations of the advanced microwave scanning radiometer on the Earth observing system (AMSR-E) at the vertical polarization. Moreover, the BMA product performs the best among the ensemble members for all vegetation classes, with a mean root-mean-square difference (RMSD) of 4 K and a temporal correlation coefficient of 0.64.展开更多
An experiment using the Community Climate System Model(CCSM4), a participant of the Coupled Model Intercomparison Project phase-5(CMIP5), is analyzed to assess the skills of this model in simulating and predicting the...An experiment using the Community Climate System Model(CCSM4), a participant of the Coupled Model Intercomparison Project phase-5(CMIP5), is analyzed to assess the skills of this model in simulating and predicting the climate variabilities associated with the oceanic channel dynamics across the Indo-Pacific Oceans. The results of these analyses suggest that the model is able to reproduce the observed lag correlation between the oceanic anomalies in the southeastern tropical Indian Ocean and those in the cold tongue in the eastern equatorial Pacific Ocean at a time lag of 1 year. This success may be largely attributed to the successful simulation of the interannual variations of the Indonesian Throughflow, which carries the anomalies of the Indian Ocean Dipole(IOD) into the western equatorial Pacific Ocean to produce subsurface temperature anomalies, which in turn propagate to the eastern equatorial Pacific to generate ENSO. This connection is termed the "oceanic channel dynamics" and is shown to be consistent with the observational analyses. However, the model simulates a weaker connection between the IOD and the interannual variability of the Indonesian Throughflow transport than found in the observations. In addition, the model overestimates the westerly wind anomalies in the western-central equatorial Pacific in the year following the IOD, which forces unrealistic upwelling Rossby waves in the western equatorial Pacific and downwelling Kelvin waves in the east. This assessment suggests that the CCSM4 coupled climate system has underestimated the oceanic channel dynamics and overestimated the atmospheric bridge processes.展开更多
The accuracy of the simulation of carbon and water processes largely relies on the selection of atmospheric forcing datasets when driving land surface models(LSM).Particularly in high-altitude regions,choosing appropr...The accuracy of the simulation of carbon and water processes largely relies on the selection of atmospheric forcing datasets when driving land surface models(LSM).Particularly in high-altitude regions,choosing appropriate atmospheric forcing datasets can effectively reduce uncertainties in the LSM simulations.Therefore,this study conducted four offline LSM simulations over the Tibetan Plateau(TP)using the Community Land Model version 4.5(CLM4.5)driven by four state-of-the-art atmospheric forcing datasets.The performances of CRUNCEP(CLM4.5 model default)and three other reanalysis-based atmospheric forcing datasets(i.e.ITPCAS,GSWP3 and WFDEI)in simulating the net primary productivity(NPP)and actual evapotranspiration(ET)were evaluated based on in situ and gridded reference datasets.Compared with in situ observations,simulated results exhibited determination coefficients(R2)ranging from 0.58 to 0.84 and 0.59 to 0.87 for observed NPP and ET,respectively,among which GSWP3 and ITPCAS showed superior performance.At the plateau level,CRUNCEP-based simulations displayed the largest bias compared with the reference NPP and ET.GSWP3-based simulations demonstrated the best performance when comprehensively considering both the magnitudes and change trends of TP-averaged NPP and ET.The simulated ET increase over the TP during 1982-2010 based on ITPCAS was significantly greater than in the other three simulations and reference ET,suggesting that ITPCAS may not be appropriate for studying long-term ET changes over the TP.These results suggest that GSWP3 is recommended for driving CLM4.5 in conducting long-term carbon and water processes simulations over the TP.This study contributes to enhancing the accuracy of LSM in water-carbon simulations over alpine regions.展开更多
Critical zone(CZ)plays a vital role in sustaining biodiversity and humanity.However,flux quantification within CZ,particularly in terms of subsurface hydrological partitioning,remains a significant challenge.This stud...Critical zone(CZ)plays a vital role in sustaining biodiversity and humanity.However,flux quantification within CZ,particularly in terms of subsurface hydrological partitioning,remains a significant challenge.This study focused on quantifying subsurface hydrological partitioning,specifically in an alpine mountainous area,and highlighted the important role of lateral flow during this process.Precipitation was usually classified as two parts into the soil:increased soil water content(SWC)and lateral flow out of the soil pit.It was found that 65%–88%precipitation contributed to lateral flow.The second common partitioning class showed an increase in SWC caused by both precipitation and lateral flow into the soil pit.In this case,lateral flow contributed to the SWC increase ranging from 43%to 74%,which was notably larger than the SWC increase caused by precipitation.On alpine meadows,lateral flow from the soil pit occurred when the shallow soil was wetter than the field capacity.This result highlighted the need for three-dimensional simulation between soil layers in Earth system models(ESMs).During evapotranspiration process,significant differences were observed in the classification of subsurface hydrological partitioning among different vegetation types.Due to tangled and aggregated fine roots in the surface soil on alpine meadows,the majority of subsurface responses involved lateral flow,which provided 98%–100%of evapotranspiration(ET).On grassland,there was a high probability(0.87),which ET was entirely provided by lateral flow.The main reason for underestimating transpiration through soil water dynamics in previous research was the neglect of lateral root water uptake.Furthermore,there was a probability of 0.12,which ET was entirely provided by SWC decrease on grassland.In this case,there was a high probability(0.98)that soil water responses only occurred at layer 2(10–20 cm),because grass roots mainly distributed in this soil layer,and grasses often used their deep roots for water uptake during ET.To improve the estimation of soil water dynamics and ET,we established a random forest(RF)model to simulate lateral flow and then corrected the community land model(CLM).RF model demonstrated good performance and led to significant improvements in CLM simulation.These findings enhance our understanding of subsurface hydrological partitioning and emphasize the importance of considering lateral flow in ESMs and hydrological research.展开更多
本文基于FVCOM(Finite Volume Community Ocean Model)构建了一个覆盖中国渤海、黄海和东海的数值模型,采用NCEP-CFSR风场数据对1509号台风“灿鸿”产生的风暴潮进行模拟,与实测水位数据的对比表明该模型可靠、模拟结果合理。基于此模型...本文基于FVCOM(Finite Volume Community Ocean Model)构建了一个覆盖中国渤海、黄海和东海的数值模型,采用NCEP-CFSR风场数据对1509号台风“灿鸿”产生的风暴潮进行模拟,与实测水位数据的对比表明该模型可靠、模拟结果合理。基于此模型,本文对非线性作用和地形在风暴潮增水过程中的作用进行了研究。首先,重点分析了增水过程中潮汐与风暴潮的非线性作用,结果表明:高潮时非线性作用使增水值降低;低潮时非线性作用使增水值升高。另外,开边界处分别只添加M2、S2和K1分潮,分析天文潮的潮高和周期对非线性作用的影响,结果表明:潮高越高,非线性作用越明显;半日潮的非线性作用较全日潮更明显;并且,增水极值附近出现的半日周期的波动也与非线性作用有关。其次,除了非线性作用,地形对风暴潮的增水也有一定影响,本文改变地形的实验结果表明:坡度越大,增水极值越小。琉球群岛的存在使得东南沿海出现风暴潮增水的面积减小,但使得风暴潮增水的高值区域扩大。展开更多
目的分析整合式慢性病社区健康管理模式实施的促进和障碍因素,区分模式服务量高覆盖率组和低覆盖率组在实施性研究的整合性理论框架(consolidated framework for implementation research,CFIR)上的结构差异,为政府部门提供政策建议。...目的分析整合式慢性病社区健康管理模式实施的促进和障碍因素,区分模式服务量高覆盖率组和低覆盖率组在实施性研究的整合性理论框架(consolidated framework for implementation research,CFIR)上的结构差异,为政府部门提供政策建议。方法结合CFIR对22名专家进行半结构化访谈,采用定性结构评级法对13家社区卫生服务中心受访者评分,利用NVivo 12软件编码。结果高覆盖率组和低覆盖率组的相对优势、外部政策与激励、实施准备度、反思和评价、领导个人特质5个CFIR结构有差异。促进因素包括:测量数据更加精准,提高了高血压和糖尿病患者的异常检出率和控制率;模式实现了服务、技术、数据“三整合”,优化管理流程,提供管理抓手;基础性和个性化服务结合吸引患者到基层就诊;模式与我国政策背景,初级卫生保健工作和以患者为中心理念兼容;数字化工具的应用减轻医护人员工作负担;领导重视是基础,利益方间的通力合作是重要保障。障碍因素包括:宏观层面缺少卫生行政机构的支持性政策,组织架构和运行机制尚未建立,建设、投入主体以及具体工作规范和流程有待明确;缺乏监督管理机制和质量评估小组;模式推广目标模糊;缺乏规范化系统性的培训计划;为不同群体提供服务存在挑战,缺乏有效的社会面宣传;模式仍须提高需方获得感;社区布局限制了模式的服务提供。结论卫生行政部门应明确模式的建设、运行、投入主体,完善组织架构并明确各利益方的功能定位和职责分工,进一步制定工作规范和工作流程;建立信息反馈机制和质量控制小组并进行定期评估;制定清晰的目标;加大宣传教育,扩大宣传面;利用数字化工具形成良性医患互动机制。展开更多
The Abdus Salam International Center for Theoretical Physics (ICTP) RegCM system is one of the most commonly used regional climate models (RCMs) over the East Asia region, In this paper, we present a brief review ...The Abdus Salam International Center for Theoretical Physics (ICTP) RegCM system is one of the most commonly used regional climate models (RCMs) over the East Asia region, In this paper, we present a brief review of the RegCM system and its applications to the East Asia region. The model history and plans for future development are described, Previous and ongoing applications, as well as the advantages and biases found in the model system over the East Asia region, are summarized, The model biases that exist are mainly found in the cold seasons, and are characterized by a warm bias at high latitudes and underestimation of precipitation in the south. These biases are similar to those of most global climate models (GCMs), Finally, future plans on the application and development of the model, and specifically on those within the context of the Coordinated Regional Climate Downscaling Experiment (CORDEX), are introduced. This paper is intended to serve as a reference for future users of the RegCM system within the East Asia region.展开更多
The Sichuan-Yunnan area is located at the southeastern margin of the Tibetan Plateau,where tectonic movement is strong with deep and large faults distributed in a staggered manner,which results in strong seismic activ...The Sichuan-Yunnan area is located at the southeastern margin of the Tibetan Plateau,where tectonic movement is strong with deep and large faults distributed in a staggered manner,which results in strong seismic activities and severe earthquake hazards.Since the 21st century,several earthquakes of magnitude 7.0 or above occurred in this region,which have caused huge casualties and economic losses,especially the 2008 M_(s)8.0 Wenchuan earthquake.At present,earthquake monitoring and source parameter inversion,strong earthquake hazard analysis and disaster assessment are still the focus of seismological researches in the Sichuan-Yunnan region.Regional high-precision 3D community velocity models are fundamental for these studies.In this paper,by assembling seismic observations at permanent seismic stations and several temporary dense seismic arrays in this region,we obtained about 7.06 million body wave travel time data(including absolute and differential travel times)using a newly developed artificial intelligence body wave arrival time picking method and about 100,000 Rayleigh wave phase velocity dispersion data in the period range of 5-50 s from ambient noise cross-correlation technique.Based on this abundant dataset,we obtained the three-dimensional high resolution V_p and V_(s)model in the crust and uppermost mantle of southwest(SW)China by adopting the joint body and surface wave travel time tomography method considering the topography effect starting from the first version of community velocity model in SW China(SWChina CVM-1.0).Compared to SWChina CVM-1.0,this newly determined velocity model has higher resolution and better data fitness.It is accepted by the China Seismic Experimental Site as the second version of the community velocity model in SW China(SWChina CVM-2.0).The new model shows strong lateral heterogeneities in the shallow crust.Two disconnected low velocity zones are observed in the middle to lower crust,which is located in the Songpan-Ganzi block and the northern Chuandian block to the west of the Longmenshan-Lijiang-Xiaojinhe fault,and beneath the Xiaojiang fault zone,respectively.The inner zone of the Emeishan large igneous province(ELIP)exhibits a high velocity anomaly,which separates the two aforementioned low velocity anomalies.Low velocity anomaly is also shown beneath the Tengchong volcano.The velocity structures in the vicinity of the 2008 M_(s)8.0 Wenchuan earthquake,the 2013 M_(s)7.0Lushan earthquake and the 2017 M_(s)7.0 Jiuzhaigou earthquake mainly show high V_(p)and V_(s)anomalies and the mainshocks are basically located at the transition zone between the high and low velocity anomalies.Along with the segmentation characteristics of seismic activity,we suggest that areas with significant changes in velocity structures,especially in active fault zones,might have a greater potential to generate moderate to strong earthquakes.展开更多
The Models-3 Community Multi-scale Air Quality modeling system (CMAQ) coupled with the Regional Atmospheric Modeling System (RAMS) is applied to East Asia to study the transport and photochemical transformation of tro...The Models-3 Community Multi-scale Air Quality modeling system (CMAQ) coupled with the Regional Atmospheric Modeling System (RAMS) is applied to East Asia to study the transport and photochemical transformation of tropospheric ozone in March 1998. The calculated mixing ratios of ozone and carbon monoxide are compared with ground level observations at three remote sites in Japan and it is found that the model reproduces the observed features very well. Examination of several high episodes of ozone and carbon monoxide indicates that these elevated levels are found in association with continental outflow, demonstrating the critical role of the rapid transport of carbon monoxide and other ozone precursors from the continental boundary layer. In comparison with available ozonesonde data, it is found that the model-calculated ozone concentrations are generally in good agreement with the measurements, and the stratospheric contribution to surface ozone mixing ratios is quite limited.展开更多
Historical haze episodes(2013–16) in Guangzhou were examined and classified according to synoptic weather systems.Four types of weather systems were found to be unfavorable, among which "foreside of a cold front"...Historical haze episodes(2013–16) in Guangzhou were examined and classified according to synoptic weather systems.Four types of weather systems were found to be unfavorable, among which "foreside of a cold front"(FC) and "sea high pressure"(SP) were the most frequent(〉 75% of the total). Targeted case studies were conducted based on an FC-affected event and an SP-affected event with the aim of understanding the characteristics of the contributions of source regions to fine particulate matter(PM(2.5)) in Guangzhou. Four kinds of contributions—namely, emissions outside Guangdong Province(super-region), emissions from the Pearl River Delta region(PRD region), emissions from Guangzhou–Foshan–Shenzhen(GFS region), and emissions from Guangzhou(local)—were investigated using the Weather Research and Forecasting–Community Multiscale Air Quality model. The results showed that the source region contribution differed with different weather systems. SP was a stagnant weather condition, and the source region contribution ratio showed that the local region was a major contributor(37%), while the PRD region, GFS region and the super-region only contributed 8%, 2.8% and 7%, respectively, to PM(2.5) concentrations. By contrast, FC favored regional transport. The super-region became noticeable,contributing 34.8%, while the local region decreased to 12%. A simple method was proposed to quantify the relative impact of meteorology and emissions. Meteorology had a 35% impact, compared with an impact of-18% for emissions, when comparing the FC-affected event with that of the SP. The results from this study can provide guidance to policymakers for the implementation of effective control strategies.展开更多
Runoff is a major component of the water cycle, and its multi-scale fluctuations are important to water resources management across arid and semi-arid regions. This paper coupled the Distributed Time Variant Gain Mod...Runoff is a major component of the water cycle, and its multi-scale fluctuations are important to water resources management across arid and semi-arid regions. This paper coupled the Distributed Time Variant Gain Model (DTVGM) into the Community Land Model (CLM 3.5), replacing the TOPMODEL-based method to simulate runoff in the arid and semi-arid regions of China. The coupled model was calibrated at five gauging stations for the period 1980-2005 and validated for the period 2006-2010. Then, future runoff (2010-2100) was simulated for different Representative Concentration Pathways (RCP) emission scenarios. After that, the spatial distributions of the future runoff for these scenarios were discussed, and the multi-scale fluctuation characteristics of the future annual runoff for the RCP scenarios were explored using the Ensemble Empirical Mode Decomposition (EEMD) analysis method. Finally, the decadal variabilities of the future annual runoff for the entire study area and the five catchments in it were investigated. The results showed that the future annual runoff had slowly decreasing trends for scenarios RCP 2.6 and RCP 8.5 during the period 2010-2100, whereas it had a non-monotonic trend for the RCP 4.5 scenario, with a slow increase after the 2050s. Additionally, the future annual runoff clearly varied over a decadal time scale, indicating that it had clear divisions between dry and wet periods. The longest dry period was approximately 15 years (2040-2055) for the RCP 2.6 scenario and 25 years (2045-2070) for the RCP 4.5 scenario. However, the RCP 8.5 scenario was predicted to have a long dry period starting from 2045. Under these scenarios, the water resources situation of the study area will be extremely severe. Therefore, adaptive water management measures addressing climate change should be adopted to proactively confront the risks of water resources.展开更多
Since May 2018,the planning,construction and functioning of China Seismic Experimental Site(CSES)has attracted much attention in earthquake science(CSES,2020 a,b,c;Wu,2020;Li et al.,2021).Different from traditional ea...Since May 2018,the planning,construction and functioning of China Seismic Experimental Site(CSES)has attracted much attention in earthquake science(CSES,2020 a,b,c;Wu,2020;Li et al.,2021).Different from traditional earthquake prediction experiment projects,such as the Parkfield earthquake prediction experiment(Roeloffs,2000).展开更多
The three-river source region plays an important role on China’s ecological security and Asia’s water supply. Historically, the region has experienced severe ecological degradation due to climate change and human ac...The three-river source region plays an important role on China’s ecological security and Asia’s water supply. Historically, the region has experienced severe ecological degradation due to climate change and human activities. Reasonable simulations of the energy and water cycles are essential to predict the responses of land surface processes to future climate change. Current land surface models involve empirical functions that are associated with many parameters. These parameter uncertainties will largely affect the simulation when applied to a new domain. The Community Land Model(CLM) is a widely used land surface model, and version 5.0 is the newest version. Compared to the prior version CLM4.5, CLM5.0 has largely updated plant hydraulic and stomatal conductance schemes. How these changes affect parameter sensitivities is unknown. In our work, we tested 17 key parameters in CLM4.5 and 19 parameters in CLM5.0 at two eddy flux sites in the three-river source region: the Maqu and Maduo sites. We adopted the simplest one-at-a-time changes on each parameter and quantified their sensitivities by the parameter effect(PE).We found that the Maqu site was more sensitive to vegetation parameters, while the Maduo site was more sensitive to the initial soil water content in both CLM4.5 and CLM5.0. This is because Maduo grid cell has wetland that does not respond to vegetation parameters in CLM, which may not reflect the reality. Further model development on wetland vegetation parameterization is important. Our validation on the default simulation showed CLM5.0 did not always improve the simulations. The largest difference between CLM5.0 and CLM4.5 was that soil moisture(SM) showed a much stronger decrease in response to a higher leaf area index(LAI) in CLM5.0 than in CLM4.5, suggesting that SM is more sensitive to vegetation changes in CLM5.0.展开更多
In this study,we conducted numerical experiments to examine the effects of turbulence parameterization on temporal and spatial variations of suspended sediment dynamics.Then,we applied the numerical model to the Yamen...In this study,we conducted numerical experiments to examine the effects of turbulence parameterization on temporal and spatial variations of suspended sediment dynamics.Then,we applied the numerical model to the Yamen Channel,one of the main eight outfalls in the Pearl River Delta.For the field application,we implemented the k−εscheme with a reasonable stability function using the continuous deposition formula during the erosion process near the water-sediment interface.We further validated and analyzed the temporal-spatial suspended sediment concentrations(SSCs).The experimental results show that under specified initial and boundary conditions,turbulence parameterization with stability functions can lead to different vertical profiles of the velocity and SSC.The k−εpredicts stronger mixing with a maximum value of approximately twice the k−kl.The k−kl results in smaller SSCs near the surface layer and a larger vertical gradient than the k−ε.In the Yamen Channel,though the turbulent dissipation,turbulent viscosity and turbulence kinetic energy exhibit similar trends,SSCs differ significantly between those at low water and high water due to the tidal asymmetry and settling lag mechanisms.The results can provide significant insights into environmental protection and estuarine management in the Pearl River Delta.展开更多
The role of sea surface temperature(SST)variability in the pre-monsoonal(April to July)intraseasonal oscillation(ISO)over the South China Sea(SCS)is investigated using the Community Earth System Model Version 2(CESM2)...The role of sea surface temperature(SST)variability in the pre-monsoonal(April to July)intraseasonal oscillation(ISO)over the South China Sea(SCS)is investigated using the Community Earth System Model Version 2(CESM2).An Atmospheric Model Intercomparison Project(AMIP)simulation forced by daily sea surface temperatures(SSTs)derived from a parallel coupled general circulation model(CGCM)run was compared with observations and the mother coupled simulation.In the coupled model,the SST warming leads the peak convection about 1/4 period as in observations.The paralell uncoupled model fails to simulate this phase relationship,implying the importance of air-sea coupling in reproducing realistic ISO.Due to the near-quadrature phase relationship between SST and precipitation ISOs during the ISO events,it is difficult to distinguish the active/passive role of SST from observations alone.Significant correlation in intraseasonal precipitation between the daily SST-forced AMIP and mother CGCM runs indicates that SST plays a role in driving the atmospheric ISO.展开更多
In order to evaluate the regulating effect of " aquatic environment protection oriented fishery" on aquatic ecosystem,the water quality,plankton community structure,biomass,diversity index,eutrophication index and e...In order to evaluate the regulating effect of " aquatic environment protection oriented fishery" on aquatic ecosystem,the water quality,plankton community structure,biomass,diversity index,eutrophication index and ecosystem maturity evaluated with Ecopath model were compared from 2010 to 2012 in Qiaodun Reservoir of Zhejiang Province. It was indicated that the water quality had been improved obviously. The water transparency maximally increased by 130%,while TP,TN and CODCrwere reduced. The density and biomass of the plankton were decreased,so was the ratio of Cynobacteria in phytoplankton community. The Shannon-Weaver index was increased; the trophic level was decreased; the ecosystem maturity was improved. By all accounts,the " aquatic environment protection oriented fishery" had positive effects on maintaining the balance of reservoir ecosystem and ensuring the safety of drinking water.展开更多
基金Under the auspices of National Basic Research Program of China(No.2010CB950102)Strategic and Special Frontier Project of Science and Technology of Chinese Academy of Sciences(No.XDA05080800)+3 种基金National Natural Science Foundation of China(No.41371209,41420104002)Special Research Fund for Doctoral Discipline of Higher Education Institutions(No.20133207110015)Natural Science Foundation of Jiangsu Higher Education Institutions(No.14KJA170002)Priority Academic Program Development of Jiangsu Higher Education Institutions(No.164320H101)
文摘Using the low-resolution (T31, equivalent to 3.75°× 3.75°) version of the Community Earth System Model (CESM) from the National Center for Atmospheric Research (NCAR), a global climate simulation was carried out with fixed external forcing factors (1850 Common Era. (C.E.) conditions) for the past 2000 years. Based on the simulated results, spatio-temporal structures of surface air temperature, precipitation and internal variability, such as the E1 Nifio-Southem Oscillation (ENSO), the Atlantic Multi-decadal Oscilla- tion (AMO), the Pacific Decadal Oscillation (PDO), and the North Atlantic Oscillation (NAO), were compared with reanalysis datasets to evaluate the model performance. The results are as follows: 1) CESM showed a good performance in the long-term simulation and no significant climate drift over the past 2000 years; 2) climatological patterns of global and regional climate changes simulated by the CESM were reasonable compared with the reanalysis datasets; and 3) the CESM simulated internal natural variability of the climate system performs very well. The model not only reproduced the periodicity of ENSO, AMO and PDO events but also the 3-8 years vari- ability of the ENSO. The spatial distribution of the CESM-simulated NAO was also similar to the observed. However, because of weaker total irradiation and greenhouse gas concentration forcing in the simulation than the present, the model performances had some differences from the observations. Generally, the CESM showed a good performance in simulating the global climate and internal natu- ral variability of the climate system. This paves the way for other forced climate simulations for the past 2000 years by using the CESM.
基金supported by the National Basic Research Program of China under Grants 2010CB951101 and 2010CB951001the National Natural Science Foundation of China under Grant 41075062
文摘The Community Microwave Emission Model (CMEM) developed by the European Centre for Me-dium-Range Weather Forecasts (ECMWF) can provide a link between surface states and satellite observations and simulate the passive microwave brightness temperature of the surface at low frequencies (from 1 GHz to 20 GHz).This study evaluated the performance of the CMEM cou-pled with the Community Land Model (CLM) (CMEM-CLM) using C-band (6.9 GHz) microwave brightness temperatures from the Advanced Microwave Scanning Radiometer on Earth Observing System (AMSR-E) over East Asia.Preliminary results support the argument that the simulated brightness temperatures of CMEM-CLM from July 2005 to June 2010 are comparable to AMSR-E observational data.CMEM-CLM performed better for vertical polarization,for which the root mean square error was approximately 15 K,compared to over 30 K for horizontal polarization.An evaluation performed over seven sub-regions in China indicated that CMEM-CLM was able to capture the temporal evolution of C-band brightness temperatures well,and the best correlation with AMSR-E appeared over western Northwest China (over 0.9 for vertical polarization).However,larger biases were found over southern North China and the middle and lower reaches of the Yangtze River.
基金supported by the National Natural Science Foundation of China (General Program (Grant No.40905042)and Key Program (Grant No. 40830956))
文摘The influences of vegetation on intraseasonal oscillation (ISO) were examined using the Community Atmosphere Model version 3 (CAM3). Two 15-year numerical experiments were completed: the first was performed with a realistic vegetation distribution (VEG run), and the second was identical to the VEG run except without land vegetation (NOVEG run). Generally speak- ing, CAM3 was able to reproduce the spatial distribution of the ISO, but the ISO intensity in the simulation was much weaker than that observed in nature: the 1SO has a relatively much stronger signal. A comparison of the VEG run with the NOVEG run revealed that the presence of vegetation usually produces a weak ISO. The vegetation effects on ISO intensity were significant over West Africa and South Asia, especially in the summer half-year. Vegetation also plays an important role in modulating ISO propagation. The eastward propagation of the ISO in the VEG run was clearer than that in the NOVEG run over the West African and Maritime Continent regions. The northward propagation of the ISO in the VEG run was more consistent with observation than that in the NOVEG run.
基金supported by Chinese Academy of Sciences (KZCX2-YW-219, 100 Tal-ents Program)Ministry of Science and Technology of China (2009CB421406)
文摘The capability of an improved Dynamic Global Vegetation Model (DGVM) in reproducing the impact of climate on the terrestrial ecosystem is evaluated. The new model incorporates the Community Land Model- DGVM (CLM3.0-DGVM) with a submodel for temperate and boreal shrubs, as well as other revisions such as the "two-leaf" scheme for photosynthesis and the definition of fractional coverage of plant functional types (PFTs). Results show that the revised model may correctly reproduce the global distribution of temperate and boreal shrubs, and improves the model performance with more realistic distribution of di?erent vege- tation types. The revised model also correctly reproduces the zonal distributions of vegetation types. In reproducing the dependence of the vegetation distribution on climate conditions, the model shows that the dominant regions for trees, grasses, shrubs, and bare soil are clearly separated by a climate index derived from mean annual precipitation and temperature, in good agreement with the CLM4 surface data. The dominant plant functional type mapping to a two dimensional parameter space of mean annual temperature and precipitation also qualitatively agrees with the results from observations and theoretical ecology studies.
基金Project supported by the China Special Fund for Meteorological Research in the Public Interest(No.GYHY201306045)the National Natural Science Foundation of China(Nos.41305066 and41575096)
文摘The choices of the parameterizations for each component in a microwave emission model have significant effects on the quality of brightness temperature (Tb) sim- ulation. How to reduce the uncertainty in the Tb simulation is investigated by adopting a statistical post-processing procedure with the Bayesian model averaging (BMA) ensemble approach. The simulations by the community microwave emission model (CMEM) cou- pled with the community land model version 4.5 (CLM4.5) over China's Mainland are con- ducted by the 24 configurations from four vegetation opacity parameterizations (VOPs), three soil dielectric constant parameterizations (SDCPs), and two soil roughness param- eterizations (SRPs). Compared with the simple arithmetical averaging (SAA) method, the BMA reconstructions have a higher spatial correlation coefficient (larger than 0.99) than the C-band satellite observations of the advanced microwave scanning radiometer on the Earth observing system (AMSR-E) at the vertical polarization. Moreover, the BMA product performs the best among the ensemble members for all vegetation classes, with a mean root-mean-square difference (RMSD) of 4 K and a temporal correlation coefficient of 0.64.
基金the National Basic Research Program of China(973 Program)(No.2012CB956000)the Strategic Priority Project of Chinese Academy of Sciences(No.XDA11010301)+2 种基金the National Natural Science Foundation of China(Nos.41421005,U1406401)the Public Welfare Grant of China Meteorological Administration(No.GYHY201306018)the Global Change and Air-Sea Interactions of State Oceanic Administration(No.GASI-03-01-01-05)
文摘An experiment using the Community Climate System Model(CCSM4), a participant of the Coupled Model Intercomparison Project phase-5(CMIP5), is analyzed to assess the skills of this model in simulating and predicting the climate variabilities associated with the oceanic channel dynamics across the Indo-Pacific Oceans. The results of these analyses suggest that the model is able to reproduce the observed lag correlation between the oceanic anomalies in the southeastern tropical Indian Ocean and those in the cold tongue in the eastern equatorial Pacific Ocean at a time lag of 1 year. This success may be largely attributed to the successful simulation of the interannual variations of the Indonesian Throughflow, which carries the anomalies of the Indian Ocean Dipole(IOD) into the western equatorial Pacific Ocean to produce subsurface temperature anomalies, which in turn propagate to the eastern equatorial Pacific to generate ENSO. This connection is termed the "oceanic channel dynamics" and is shown to be consistent with the observational analyses. However, the model simulates a weaker connection between the IOD and the interannual variability of the Indonesian Throughflow transport than found in the observations. In addition, the model overestimates the westerly wind anomalies in the western-central equatorial Pacific in the year following the IOD, which forces unrealistic upwelling Rossby waves in the western equatorial Pacific and downwelling Kelvin waves in the east. This assessment suggests that the CCSM4 coupled climate system has underestimated the oceanic channel dynamics and overestimated the atmospheric bridge processes.
基金supported by the National Key Research and Development Program of China(2022YFC3201702)the National Natural Science Foundation of China(42201146,U2240226)+1 种基金the Science and Technology Project of Sichuan Province(2022NSFSC1001)Fundamental Research Funds for The Central Universities(YJ2021133).
文摘The accuracy of the simulation of carbon and water processes largely relies on the selection of atmospheric forcing datasets when driving land surface models(LSM).Particularly in high-altitude regions,choosing appropriate atmospheric forcing datasets can effectively reduce uncertainties in the LSM simulations.Therefore,this study conducted four offline LSM simulations over the Tibetan Plateau(TP)using the Community Land Model version 4.5(CLM4.5)driven by four state-of-the-art atmospheric forcing datasets.The performances of CRUNCEP(CLM4.5 model default)and three other reanalysis-based atmospheric forcing datasets(i.e.ITPCAS,GSWP3 and WFDEI)in simulating the net primary productivity(NPP)and actual evapotranspiration(ET)were evaluated based on in situ and gridded reference datasets.Compared with in situ observations,simulated results exhibited determination coefficients(R2)ranging from 0.58 to 0.84 and 0.59 to 0.87 for observed NPP and ET,respectively,among which GSWP3 and ITPCAS showed superior performance.At the plateau level,CRUNCEP-based simulations displayed the largest bias compared with the reference NPP and ET.GSWP3-based simulations demonstrated the best performance when comprehensively considering both the magnitudes and change trends of TP-averaged NPP and ET.The simulated ET increase over the TP during 1982-2010 based on ITPCAS was significantly greater than in the other three simulations and reference ET,suggesting that ITPCAS may not be appropriate for studying long-term ET changes over the TP.These results suggest that GSWP3 is recommended for driving CLM4.5 in conducting long-term carbon and water processes simulations over the TP.This study contributes to enhancing the accuracy of LSM in water-carbon simulations over alpine regions.
基金funded by the National Natural Science Foundation of China(42371022,42030501,41877148).
文摘Critical zone(CZ)plays a vital role in sustaining biodiversity and humanity.However,flux quantification within CZ,particularly in terms of subsurface hydrological partitioning,remains a significant challenge.This study focused on quantifying subsurface hydrological partitioning,specifically in an alpine mountainous area,and highlighted the important role of lateral flow during this process.Precipitation was usually classified as two parts into the soil:increased soil water content(SWC)and lateral flow out of the soil pit.It was found that 65%–88%precipitation contributed to lateral flow.The second common partitioning class showed an increase in SWC caused by both precipitation and lateral flow into the soil pit.In this case,lateral flow contributed to the SWC increase ranging from 43%to 74%,which was notably larger than the SWC increase caused by precipitation.On alpine meadows,lateral flow from the soil pit occurred when the shallow soil was wetter than the field capacity.This result highlighted the need for three-dimensional simulation between soil layers in Earth system models(ESMs).During evapotranspiration process,significant differences were observed in the classification of subsurface hydrological partitioning among different vegetation types.Due to tangled and aggregated fine roots in the surface soil on alpine meadows,the majority of subsurface responses involved lateral flow,which provided 98%–100%of evapotranspiration(ET).On grassland,there was a high probability(0.87),which ET was entirely provided by lateral flow.The main reason for underestimating transpiration through soil water dynamics in previous research was the neglect of lateral root water uptake.Furthermore,there was a probability of 0.12,which ET was entirely provided by SWC decrease on grassland.In this case,there was a high probability(0.98)that soil water responses only occurred at layer 2(10–20 cm),because grass roots mainly distributed in this soil layer,and grasses often used their deep roots for water uptake during ET.To improve the estimation of soil water dynamics and ET,we established a random forest(RF)model to simulate lateral flow and then corrected the community land model(CLM).RF model demonstrated good performance and led to significant improvements in CLM simulation.These findings enhance our understanding of subsurface hydrological partitioning and emphasize the importance of considering lateral flow in ESMs and hydrological research.
文摘本文基于FVCOM(Finite Volume Community Ocean Model)构建了一个覆盖中国渤海、黄海和东海的数值模型,采用NCEP-CFSR风场数据对1509号台风“灿鸿”产生的风暴潮进行模拟,与实测水位数据的对比表明该模型可靠、模拟结果合理。基于此模型,本文对非线性作用和地形在风暴潮增水过程中的作用进行了研究。首先,重点分析了增水过程中潮汐与风暴潮的非线性作用,结果表明:高潮时非线性作用使增水值降低;低潮时非线性作用使增水值升高。另外,开边界处分别只添加M2、S2和K1分潮,分析天文潮的潮高和周期对非线性作用的影响,结果表明:潮高越高,非线性作用越明显;半日潮的非线性作用较全日潮更明显;并且,增水极值附近出现的半日周期的波动也与非线性作用有关。其次,除了非线性作用,地形对风暴潮的增水也有一定影响,本文改变地形的实验结果表明:坡度越大,增水极值越小。琉球群岛的存在使得东南沿海出现风暴潮增水的面积减小,但使得风暴潮增水的高值区域扩大。
文摘The Abdus Salam International Center for Theoretical Physics (ICTP) RegCM system is one of the most commonly used regional climate models (RCMs) over the East Asia region, In this paper, we present a brief review of the RegCM system and its applications to the East Asia region. The model history and plans for future development are described, Previous and ongoing applications, as well as the advantages and biases found in the model system over the East Asia region, are summarized, The model biases that exist are mainly found in the cold seasons, and are characterized by a warm bias at high latitudes and underestimation of precipitation in the south. These biases are similar to those of most global climate models (GCMs), Finally, future plans on the application and development of the model, and specifically on those within the context of the Coordinated Regional Climate Downscaling Experiment (CORDEX), are introduced. This paper is intended to serve as a reference for future users of the RegCM system within the East Asia region.
基金supported by the National Natural Science Foundation of China(Grant Nos.42004034,U1839205,42125401)the Special Fund of the Institute of Geophysics,China Earthquake Administration(Grant No.DQJB22Z01)the National Key R&D Program of China(Grant No.2021YFC3000602)。
文摘The Sichuan-Yunnan area is located at the southeastern margin of the Tibetan Plateau,where tectonic movement is strong with deep and large faults distributed in a staggered manner,which results in strong seismic activities and severe earthquake hazards.Since the 21st century,several earthquakes of magnitude 7.0 or above occurred in this region,which have caused huge casualties and economic losses,especially the 2008 M_(s)8.0 Wenchuan earthquake.At present,earthquake monitoring and source parameter inversion,strong earthquake hazard analysis and disaster assessment are still the focus of seismological researches in the Sichuan-Yunnan region.Regional high-precision 3D community velocity models are fundamental for these studies.In this paper,by assembling seismic observations at permanent seismic stations and several temporary dense seismic arrays in this region,we obtained about 7.06 million body wave travel time data(including absolute and differential travel times)using a newly developed artificial intelligence body wave arrival time picking method and about 100,000 Rayleigh wave phase velocity dispersion data in the period range of 5-50 s from ambient noise cross-correlation technique.Based on this abundant dataset,we obtained the three-dimensional high resolution V_p and V_(s)model in the crust and uppermost mantle of southwest(SW)China by adopting the joint body and surface wave travel time tomography method considering the topography effect starting from the first version of community velocity model in SW China(SWChina CVM-1.0).Compared to SWChina CVM-1.0,this newly determined velocity model has higher resolution and better data fitness.It is accepted by the China Seismic Experimental Site as the second version of the community velocity model in SW China(SWChina CVM-2.0).The new model shows strong lateral heterogeneities in the shallow crust.Two disconnected low velocity zones are observed in the middle to lower crust,which is located in the Songpan-Ganzi block and the northern Chuandian block to the west of the Longmenshan-Lijiang-Xiaojinhe fault,and beneath the Xiaojiang fault zone,respectively.The inner zone of the Emeishan large igneous province(ELIP)exhibits a high velocity anomaly,which separates the two aforementioned low velocity anomalies.Low velocity anomaly is also shown beneath the Tengchong volcano.The velocity structures in the vicinity of the 2008 M_(s)8.0 Wenchuan earthquake,the 2013 M_(s)7.0Lushan earthquake and the 2017 M_(s)7.0 Jiuzhaigou earthquake mainly show high V_(p)and V_(s)anomalies and the mainshocks are basically located at the transition zone between the high and low velocity anomalies.Along with the segmentation characteristics of seismic activity,we suggest that areas with significant changes in velocity structures,especially in active fault zones,might have a greater potential to generate moderate to strong earthquakes.
基金supported by the National Natural Science Foundation of China(Grant No.40245029)the Hundred Talents Program(Global Environmental Change)from the Chinese Academy of Sciences.
文摘The Models-3 Community Multi-scale Air Quality modeling system (CMAQ) coupled with the Regional Atmospheric Modeling System (RAMS) is applied to East Asia to study the transport and photochemical transformation of tropospheric ozone in March 1998. The calculated mixing ratios of ozone and carbon monoxide are compared with ground level observations at three remote sites in Japan and it is found that the model reproduces the observed features very well. Examination of several high episodes of ozone and carbon monoxide indicates that these elevated levels are found in association with continental outflow, demonstrating the critical role of the rapid transport of carbon monoxide and other ozone precursors from the continental boundary layer. In comparison with available ozonesonde data, it is found that the model-calculated ozone concentrations are generally in good agreement with the measurements, and the stratospheric contribution to surface ozone mixing ratios is quite limited.
基金supported by the National Key R&D Program of China:Task 3(Grant No.2016 YFC0202000)Guangzhou Science and Technology Plan(Grant No.201604020028)+3 种基金National Natural Science Foundation of China(Grant No.41775037 and 41475105)Science and Technology Innovative Research Team Plan of Guangdong Meteorological Bureau(Grant No.201704)Guangdong Natural Science FoundationMajor Research Training Project(2015A030308014)a science and technology study project of Guangdong Meteorological Bureau(Grant No.2015Q03)
文摘Historical haze episodes(2013–16) in Guangzhou were examined and classified according to synoptic weather systems.Four types of weather systems were found to be unfavorable, among which "foreside of a cold front"(FC) and "sea high pressure"(SP) were the most frequent(〉 75% of the total). Targeted case studies were conducted based on an FC-affected event and an SP-affected event with the aim of understanding the characteristics of the contributions of source regions to fine particulate matter(PM(2.5)) in Guangzhou. Four kinds of contributions—namely, emissions outside Guangdong Province(super-region), emissions from the Pearl River Delta region(PRD region), emissions from Guangzhou–Foshan–Shenzhen(GFS region), and emissions from Guangzhou(local)—were investigated using the Weather Research and Forecasting–Community Multiscale Air Quality model. The results showed that the source region contribution differed with different weather systems. SP was a stagnant weather condition, and the source region contribution ratio showed that the local region was a major contributor(37%), while the PRD region, GFS region and the super-region only contributed 8%, 2.8% and 7%, respectively, to PM(2.5) concentrations. By contrast, FC favored regional transport. The super-region became noticeable,contributing 34.8%, while the local region decreased to 12%. A simple method was proposed to quantify the relative impact of meteorology and emissions. Meteorology had a 35% impact, compared with an impact of-18% for emissions, when comparing the FC-affected event with that of the SP. The results from this study can provide guidance to policymakers for the implementation of effective control strategies.
基金supported by the National Basic Research Program of China(2012CB956204)We acknowledge the modeling groups for providing the data for analysis,the Program for Climate Model Diagnosis and Intercomparison(PCMDI)the World Climate Research Programme’s(WCRP’s)Coupled Model Intercomparison Project for collecting and archiving the model output and organizing the data analysis
文摘Runoff is a major component of the water cycle, and its multi-scale fluctuations are important to water resources management across arid and semi-arid regions. This paper coupled the Distributed Time Variant Gain Model (DTVGM) into the Community Land Model (CLM 3.5), replacing the TOPMODEL-based method to simulate runoff in the arid and semi-arid regions of China. The coupled model was calibrated at five gauging stations for the period 1980-2005 and validated for the period 2006-2010. Then, future runoff (2010-2100) was simulated for different Representative Concentration Pathways (RCP) emission scenarios. After that, the spatial distributions of the future runoff for these scenarios were discussed, and the multi-scale fluctuation characteristics of the future annual runoff for the RCP scenarios were explored using the Ensemble Empirical Mode Decomposition (EEMD) analysis method. Finally, the decadal variabilities of the future annual runoff for the entire study area and the five catchments in it were investigated. The results showed that the future annual runoff had slowly decreasing trends for scenarios RCP 2.6 and RCP 8.5 during the period 2010-2100, whereas it had a non-monotonic trend for the RCP 4.5 scenario, with a slow increase after the 2050s. Additionally, the future annual runoff clearly varied over a decadal time scale, indicating that it had clear divisions between dry and wet periods. The longest dry period was approximately 15 years (2040-2055) for the RCP 2.6 scenario and 25 years (2045-2070) for the RCP 4.5 scenario. However, the RCP 8.5 scenario was predicted to have a long dry period starting from 2045. Under these scenarios, the water resources situation of the study area will be extremely severe. Therefore, adaptive water management measures addressing climate change should be adopted to proactively confront the risks of water resources.
基金granted by National Natural Science Foundation of China(NSFC,Grant No.U2039207).
文摘Since May 2018,the planning,construction and functioning of China Seismic Experimental Site(CSES)has attracted much attention in earthquake science(CSES,2020 a,b,c;Wu,2020;Li et al.,2021).Different from traditional earthquake prediction experiment projects,such as the Parkfield earthquake prediction experiment(Roeloffs,2000).
基金Supported by the Strategic Priority Research Program of Chinese Academy of Sciences(XDA20050102)National Natural Science Foundation of China(41975135 and 41975130)。
文摘The three-river source region plays an important role on China’s ecological security and Asia’s water supply. Historically, the region has experienced severe ecological degradation due to climate change and human activities. Reasonable simulations of the energy and water cycles are essential to predict the responses of land surface processes to future climate change. Current land surface models involve empirical functions that are associated with many parameters. These parameter uncertainties will largely affect the simulation when applied to a new domain. The Community Land Model(CLM) is a widely used land surface model, and version 5.0 is the newest version. Compared to the prior version CLM4.5, CLM5.0 has largely updated plant hydraulic and stomatal conductance schemes. How these changes affect parameter sensitivities is unknown. In our work, we tested 17 key parameters in CLM4.5 and 19 parameters in CLM5.0 at two eddy flux sites in the three-river source region: the Maqu and Maduo sites. We adopted the simplest one-at-a-time changes on each parameter and quantified their sensitivities by the parameter effect(PE).We found that the Maqu site was more sensitive to vegetation parameters, while the Maduo site was more sensitive to the initial soil water content in both CLM4.5 and CLM5.0. This is because Maduo grid cell has wetland that does not respond to vegetation parameters in CLM, which may not reflect the reality. Further model development on wetland vegetation parameterization is important. Our validation on the default simulation showed CLM5.0 did not always improve the simulations. The largest difference between CLM5.0 and CLM4.5 was that soil moisture(SM) showed a much stronger decrease in response to a higher leaf area index(LAI) in CLM5.0 than in CLM4.5, suggesting that SM is more sensitive to vegetation changes in CLM5.0.
基金Supported by the Scientific Research Start-up Funds of Guangdong Ocean University(Grant No.060302032202).
文摘In this study,we conducted numerical experiments to examine the effects of turbulence parameterization on temporal and spatial variations of suspended sediment dynamics.Then,we applied the numerical model to the Yamen Channel,one of the main eight outfalls in the Pearl River Delta.For the field application,we implemented the k−εscheme with a reasonable stability function using the continuous deposition formula during the erosion process near the water-sediment interface.We further validated and analyzed the temporal-spatial suspended sediment concentrations(SSCs).The experimental results show that under specified initial and boundary conditions,turbulence parameterization with stability functions can lead to different vertical profiles of the velocity and SSC.The k−εpredicts stronger mixing with a maximum value of approximately twice the k−kl.The k−kl results in smaller SSCs near the surface layer and a larger vertical gradient than the k−ε.In the Yamen Channel,though the turbulent dissipation,turbulent viscosity and turbulence kinetic energy exhibit similar trends,SSCs differ significantly between those at low water and high water due to the tidal asymmetry and settling lag mechanisms.The results can provide significant insights into environmental protection and estuarine management in the Pearl River Delta.
基金Supported by the National Natural Science Foundation of China(No.42090042)the Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(No.2019BT02H594)the Chinese Academy of Sciences(Nos.XDB42010304,133244KYSB20190031,183311KYSB20200015,SCSIO202201)。
文摘The role of sea surface temperature(SST)variability in the pre-monsoonal(April to July)intraseasonal oscillation(ISO)over the South China Sea(SCS)is investigated using the Community Earth System Model Version 2(CESM2).An Atmospheric Model Intercomparison Project(AMIP)simulation forced by daily sea surface temperatures(SSTs)derived from a parallel coupled general circulation model(CGCM)run was compared with observations and the mother coupled simulation.In the coupled model,the SST warming leads the peak convection about 1/4 period as in observations.The paralell uncoupled model fails to simulate this phase relationship,implying the importance of air-sea coupling in reproducing realistic ISO.Due to the near-quadrature phase relationship between SST and precipitation ISOs during the ISO events,it is difficult to distinguish the active/passive role of SST from observations alone.Significant correlation in intraseasonal precipitation between the daily SST-forced AMIP and mother CGCM runs indicates that SST plays a role in driving the atmospheric ISO.
基金Supported by Special Project of Public Welfare Industry(Agriculture)Science Research,Ministry of Agriculture,China(201303056)Zhejiang Standardization Research Project,China(2010-10)
文摘In order to evaluate the regulating effect of " aquatic environment protection oriented fishery" on aquatic ecosystem,the water quality,plankton community structure,biomass,diversity index,eutrophication index and ecosystem maturity evaluated with Ecopath model were compared from 2010 to 2012 in Qiaodun Reservoir of Zhejiang Province. It was indicated that the water quality had been improved obviously. The water transparency maximally increased by 130%,while TP,TN and CODCrwere reduced. The density and biomass of the plankton were decreased,so was the ratio of Cynobacteria in phytoplankton community. The Shannon-Weaver index was increased; the trophic level was decreased; the ecosystem maturity was improved. By all accounts,the " aquatic environment protection oriented fishery" had positive effects on maintaining the balance of reservoir ecosystem and ensuring the safety of drinking water.