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1.
In this study, we analyze results from 47-year (1954?C2000) offline simulations using an Australian land-surface model CSIRO Atmosphere Biosphere Land Exchange. We focus on exploring its surface mean climatology, interannual and decadal variations in Australia and Amazonia basin in South America which are distinguished by dry and wet climates respectively. Its skill is assessed by using observational datasets and four model products from the Global Land-surface Data Assimilation System. Surface evaporation and runoff climatologies are satisfactorily simulated, including surface energy and water partitions in dry and wet climates. In the Australian continent dominated by dry climate, slowly varying soil moisture processes are simulated in the southeast during austral winter. The model is skilful in reproducing the nonlinear relationship between rainfall and runoff variations in the southwestern part of the Australia. It shows that the significant downward trend of river inflow in the region is associated with enhanced surface evaporation which is caused by increased surface radiation and wind speed. In its carbon-cycle modeling, the model simulates an upward trend of NPP by about 0.69%/year over the Amazonia forest region in the 47-year period. By comparing two sets of the model results with/without CO2 variations, it shows that 35% of such increases are caused by changes in climatic conditions, while 65% is due to the increase in atmospheric CO2 concentration. Given the close linkage between climate, water and vegetation (carbon cycle), this work promotes an integrated modeling and evaluation approach for better representation of land-surface processes in Earth system studies.  相似文献   

2.
F. Chen 《Climate Dynamics》2005,24(7-8):667-684
The International Satellite Land-Surface Climatology Project (ISLSCP) Initiative-I 1-degree 1987–1988 data were used to drive a land surface model (LSM) to simulate global surface energy budgets. Simulated surface heat fluxes show remarkable spatial variability and seem to capture well their annual and interannual variability. A shift of maximum evaporation across the equator is more closely related to the seasonal shifting of precipitation pattern than to surface radiation changes. The NCEP/NCAR reanalysis did not reflect this shift, presumably due to its dominant rainfall maximum in the Southern Hemisphere. To assess the “reliability” of these fields, both Global Soil Wetness Project (GSWP) and reanalysis were verified against observations, at two sites. Monthly mean ISLSCP forcing conditions agree fairly well with observations, but its precipitation is usually lower during spring and summer. Low summer GSWP evaporation may be due to low precipitation and incorrect specification of vegetation and soil conditions. The reanalysis had larger seasonal variability than GSWP and observations, and overestimated summer heat fluxes because of its large rainfall and surface radiation. Despite uncertainty in ISLSCP data, an LSM with a modest treatment of vegetation was able to capture reasonably well the seasonal variations in surface heat fluxes at global scales. With some caution, these types of simulations can be used as “pseudo-observations” to evaluate climate-model simulations and to investigate global energy budgets. For the next phase of ISLSCP data development, higher resolution data, which can reflect local heterogeneity of vegetation and soil characteristics, include more rain gauge data are highly desirable to improve model simulations.  相似文献   

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为研究不同陆面模式对中国区域土壤温度的模拟效果,基于中国气象局陆面数据同化系统(CMA Land Data Assimilation System,CLDAS)大气驱动数据分别驱动Noah和Noah-MP陆面模式进行中国区域土壤温度的模拟(简称:CLDAS_Noah和CLDAS_Noah-MP试验),使用2010—2018年中国气象局2380个土壤温度观测站点10和40 cm观测数据以及美国全球陆面数据同化系统(The Global Land Data Assimilation System,GLDAS)驱动的Noah模式(GLDAS_Noah试验)模拟的土壤温度结果,从空间分布、季节、分区等角度进行了评估,实现了不同驱动数据相同陆面模式和相同驱动数据不同陆面模式的对比分析。结果表明: GLDAS_Noah、CLDAS_Noah和CLDAS_Noah-MP试验均能合理模拟出中国区域土壤温度空间分布,但在量级上有一定差异,主要表现在中国东北、新疆、青藏高原等积雪区。对于相同陆面模式不同驱动数据,均方根误差显示CLDAS_Noah试验在季节与分区上均优于GLDAS_Noah试验,间接表明CLDAS大气驱动数据优于GLDAS大气驱动数据,且大气驱动数据是提高土壤温度模拟精度的重要因素之一;对于相同驱动数据不同陆面模式,总体上CLDAS_Noah-MP试验棋拟效果优于CLDAS_Noah试验,其中CLDAS_Noah试验模拟的10和40 cm深度土壤温度在冬季积雪区误差明显大于CLDAS_Noah-MP试验,可能与Noah-MP模式改进了积雪方案有关,但10和40 cm深度下CLDAS_Noah-MP试验在东北、华北、青藏高原地区对春季土壤温度模拟误差明显大于CLDAS_Noah试验,可能与Noah-MP模式融雪方案有关。总之,本研究对于后续开展土壤温度多模式集成、土壤温度站点资料同化,最终研制中国区域高质量土壤温度数据集具有一定的参考意义。   相似文献   

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A study of the performance of a land surface process model (LSPM)   总被引:1,自引:0,他引:1  
In this paper, a reliable Land-Surface Process Model (LSPM), which is a new version of the LPM of Ji and Hu (1989), is described. The LSPM has been validated with experimental data measured at two stations in the Po Valley (Northern Italy).  相似文献   

7.
SimulationoftheAsianMonsoonbyIAPAGCMCoupledwithanAdvancedLandSurfaceModel(IAP94)ZengQingcun(曾庆存),DaiYongjiu(戴永久)andXueFeng(薛峰...  相似文献   

8.
The Loess Plateau, located in northern China, has a significant impact on the climate and ecosystem evolvement over the East Asian continent. In this paper, the preliminary autumn daily characteristics of land surface energy and water exchange over the Chinese Loess Plateau mesa region are evaluated by using data collected during the Loess Plateau land-atmosphere interaction pilot experiment (LOPEX04), which was conducted from 25 August to 12 September 2004 near Pingliang city, Gansu Province of China. The experiment was carried out in a region with a typical landscape of the Chinese Loess Plateau, known as "loess mesa". The experiment's field land utilizations were cornfield and fallow farmland, with the fallow field later used for rotating winter wheat. The autumn daily characteristics of heat and water exchange evidently differed between the mesa cornfield and fallow, and the imbalance term of the surface energy was large. This is discussed in terms of sampling errors in the flux observations-footprint; energy storage terms of soil and vegetation layers; contribution from air advections; and low and high frequency loss of turbulent fluxes and instruments bias. Comparison of energy components between the mesa cornfield and the lowland cornfield did not reveal any obvious difference. Inadequacies of the field observation equipment and experimental design emerged during the study, and some new research topics have emerged from this pilot experiment for future investigation.  相似文献   

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In 1989, the need for reliable gridded land surface precipitation data sets, in view of the large uncertainties in the assessment of the global energy and water cycle, has led to the establishment of the Global Precipitation Climatology Centre (GPCC) at Deutscher Wetterdienst on invitation of the WMO. The GPCC has calculated a precipitation climatology for the global land areas for the target period 1951–2000 by objective analysis of climatological normals of about 67,200 rain gauge stations from its data base. GPCC's new precipitation climatology is compared to several other station-based precipitation climatologies as well as to precipitation climatologies derived from the GPCP V2.2 data set and from ECMWF's model reanalyses ERA-40 and ERA-Interim. Finally, how GPCC's best estimate for terrestrial mean precipitation derived from the precipitation climatology of 786 mm per year (equivalent to a water transport of 117,000 km3) is fitting into the global water cycle context is discussed.  相似文献   

11.
利用NCAR大气环流模式CAM4.0,针对潜在植被和当代植被的分布情形进行了两组25 a的积分试验,探讨了土地利用变化对东亚地区地表能量平衡、水分循环和气候的可能影响.结果表明:以森林退化、农田迅速增加为主的当代土地利用变化,显著改变地表属性,使得东亚地区不同季节的地表反照率均明显增加,并显著改变东亚地区的冬、春季节的地表能量和水分循环.此外,当代大尺度土地利用变化对东亚地区大气环流也有一定影响,可引起东亚冬季风环流显著加强和东亚夏季较弱的偏南风异常.当代土地利用变化未能引起东亚地区近地面气温的显著变化,但可引起东亚北(南)部地区春季降水的显著增加(减小).  相似文献   

12.
情景是气候变化研究的重要工具。为了科学支撑气候变化科学评估和研究,2010年政府间气候变化专门委员会(IPCC)提出了共享社会经济路径(Shared Socioeconomic Pathways, SSPs)。作为从社会经济变化视角构建的气候情景,SSPs促进了气候变化科学基础、影响、脆弱性、风险、适应和减缓等学科的综合研究。本文介绍了SSPs情景研发与应用过程;阐述了全球和中国的人口经济、土地利用、能源和碳排放的模拟和预估主要成果;探讨了全球和中国碳排放路径及其与“双碳”目标的关系;并展望了SSPs应用前景。  相似文献   

13.
Storm tracks play a major role in regulating the precipitation and hydrological cycle in midlatitudes. The changes in the location and amplitude of the storm tracks in response to global warming will have significant impacts on the poleward transport of heat, momentum and moisture and on the hydrological cycle. Recent studies have indicated a poleward shift of the storm tracks and the midlatitude precipitation zone in the warming world that will lead to subtropical drying and higher latitude moistening. This study agrees with this key feature for not only the annual mean but also different seasons and for the zonal mean as well as horizontal structures based on the analysis of Geophysical Fluid Dynamics Laboratory (GFDL) CM2.1 model simulations. Further analyses show that the meridional sensible and latent heat fluxes associated with the storm tracks shift poleward and intensify in both boreal summer and winter in the late twenty-first century (years 2081?C2100) relative to the latter half of the twentieth century (years 1961?C2000). The maximum dry Eady growth rate is examined to determine the effect of global warming on the time mean state and associated available potential energy for transient growth. The trend in maximum Eady growth rate is generally consistent with the poleward shift and intensification of the storm tracks in the middle latitudes of both hemispheres in both seasons. However, in the lower troposphere in northern winter, increased meridional eddy transfer within the storm tracks is more associated with increased eddy velocity, stronger correlation between eddy velocity and eddy moist static energy, and longer eddy length scale. The changing characteristics of baroclinic instability are, therefore, needed to explain the storm track response as climate warms. Diagnosis of the latitude-by-latitude energy budget for the current and future climate demonstrates how the coupling between radiative and surface heat fluxes and eddy heat and moisture transport influences the midlatitude storm track response to global warming. Through radiative forcing by increased atmospheric carbon dioxide and water vapor, more energy is gained within the tropics and subtropics, while in the middle and high latitudes energy is reduced through increased outgoing terrestrial radiation in the Northern Hemisphere and increased ocean heat uptake in the Southern Hemisphere. This enhanced energy imbalance in the future climate requires larger atmospheric energy transports in the midlatitudes which are partially accomplished by intensified storm tracks. Finally a sequence of cause and effect for the storm track response in the warming world is proposed that combines energy budget constraints with baroclinic instability theory.  相似文献   

14.
Three experiments for the simulation of typhoon Sinlaku (2002) over the western North Pacific are performed in this study by using the Canadian Mesoscale Compressible Community (MC2) atmospheric model. The objective of these simulations is to investigate the air-sea interaction during extreme weather conditions, and to determine the sensitivity of the typhoon evolution to the sea surface temperature (SST)cooling induced by the typhoon. It is shown from the three experiments that the surface heat fluxes have a substantial influence on the slow-moving cyclone over its lifetime. When the SST in the East China coastal ocean becomes 1℃ cooler in the simulation, less latent heat and sensible heat fluxes from the underlying ocean to the cyclone tend to reduce the typhoon intensity. The cyclone is weakened by 7 hPa at the time of its peak intensity. The SST cooling also has impacts on the vertical structure of the typhoon by weakening the warm core and drying the eye wall. With a finer horizontal resolution of (1/6)°×(1/6)°, the model produces higher surface wind, and therefore more surface heat fluxes are emitted from the ocean surface to the cyclone, in the finer-resolution MC2 grid compared with the relatively lower resolution of 0.25°×0.25°MC2 grid.  相似文献   

15.
区域气候模式Reg CM最新版中引入了新的陆面模式CLM,为了考察在选用CLM时不同对流参数化方案在中国地区的表现,本文进行了五种不同对流参数化方案下—Grell、Emanuel、Tiedtke,Mix(陆地上位Emanuel方案,海洋上为Grell方案)和Mix2(陆地上为Grell方案,海洋上为Emanuel方案)的模拟试验。将模拟的冬、夏季平均气温和降水与观测进行了对比分析,结果表明,Emanuel方案是综合模拟效果最好的。在使用Reg CM-CLM进行中国区域模拟研究时,对流参数化方案推荐选为Emanuel。  相似文献   

16.
The dominant parameters in the Noah land surface model (LSM) are identified, and the effects of parameter optimization on the surface heat exchange are investigated at a temperate desert steppe site during growing season in Inner Mongolia, China. The relative impacts of parameters on surface heat flux are examined by the distributed evaluation of local sensitivity analysis (DELSA), and the Noah LSM is calibrated by the global shuffled complex evolution (SCE) against the corresponding observations during May–September of 2008 and 2009. The differences in flux simulations are assessed between the Noah LSM calibrated by the SCE with 27 parameters and 12 dominant parameters. The systematic error, unsystematic error, root mean squared error, and mean squared error decompositions are used to evaluate the model performance. Compared to the control experiment, parameter optimization by the SCE using net radiation, sensible heat flux, latent heat flux, and ground heat flux as the objective criterion, respectively, can obviously reduce the errors of the Noah LSM. The calibrated Noah LSM is further validated against flux observations of growing season in 2010, and it is found that the calibrated Noah LSM can be applied in the longer term at this site. The Noah LSM with 12 dominant parameters calibrated performs similar to that with 27 parameters calibrated.  相似文献   

17.
This study explores natural and anthropogenic influences on the climate system, with an emphasis on the biogeophysical and biogeochemical effects of historical land cover change. The biogeophysical effect of land cover change is first subjected to a detailed sensitivity analysis in the context of the UVic Earth System Climate Model, a global climate model of intermediate complexity. Results show a global cooling in the range of –0.06 to –0.22 °C, though this effect is not found to be detectable in observed temperature trends. We then include the effects of natural forcings (volcanic aerosols, solar insolation variability and orbital changes) and other anthropogenic forcings (greenhouse gases and sulfate aerosols). Transient model runs from the year 1700 to 2000 are presented for each forcing individually as well as for combinations of forcings. We find that the UVic Model reproduces well the global temperature data when all forcings are included. These transient experiments are repeated using a dynamic vegetation model coupled interactively to the UVic Model. We find that dynamic vegetation acts as a positive feedback in the climate system for both the all-forcings and land cover change only model runs. Finally, the biogeochemical effect of land cover change is explored using a dynamically coupled inorganic ocean and terrestrial carbon cycle model. The carbon emissions from land cover change are found to enhance global temperatures by an amount that exceeds the biogeophysical cooling. The net effect of historical land cover change over this period is to increase global temperature by 0.15 °C.  相似文献   

18.
BCC气候模式对中国近50a极端气候事件的模拟评估   总被引:3,自引:1,他引:3  
利用中国区域437站1958—2005年逐日气温和降水资料,评估了国家气候中心(BeijingCli-mateCenter,BCC)气候模式对中国近50a极端气候事件空间分布、时间演变等方面的模拟能力。结果表明:1)模式对极端温度和降水多年平均的空间分布具有一定的模拟能力,但尚存在系统性的偏差。暖昼日数的模拟优于冷夜日数,全年冷夜日数的模拟优于冬季和夏季的模拟,而全年和夏季暖昼日数的模拟优于冬季的模拟。极端降水频次的模拟优于极端降水量的模拟;夏季和全年的模拟优于冬季的模拟。夏季极端降水频次的模拟较好,但冬季的模拟在长江中下游和华南偏小、北方偏大,而全年的模拟在长江下游及南部沿海地区系统性偏大;夏季和全年极端降水量的模拟系统性偏低,而冬季在北方偏高、南方偏低。2)模式较好地模拟出了夏季和全年冷夜日数的全国较为一致的减少趋势,再现东北和东南沿海地区冬季冷夜日数的减少趋势,但模拟的趋势较实测偏弱。模式对暖昼日数长期趋势的模拟效果较理想,较好地反映出了大部分地区暖昼事件发生频率显著增加的特征,但冬季的模拟尚有待改进。模式较好地模拟出了夏季和全年极端降水频次的长期趋势,较好地刻画了极端降水频次"南增北减"的特征;模式对冬季极端降水频次的变化趋势几乎无模拟能力。同样,模式也较好地模拟出了极端降水量夏季南增北减的分布形势和冬季的总体增加趋势,但对全年的模拟不理想。3)模式能较好地模拟出冷夜日数和暖昼日数异常变化的主要空间型,对EOF第一模态的时间演变特征具有一定模拟能力;但模式对第二模态时间演变特征的刻画能力较差。模式对极端降水指标的年际变化具有一定的模拟能力,对部分区域极端降水事件的年际变化具有较好的模拟能力;但模拟能力表现出了明显的区域性差异,部分区域极端降水年际变化的模拟结果与实况甚至相反,模式对极端降水年际变化的模拟能力还有待提高。所得结果可为BCC气候模式的改进及极端气候模拟、预估提供一定的参考。  相似文献   

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The impact of land use change on regional climate can be substantial but also is variable in space and time. Past observational and modeling work suggests that in a ‘Mediterranean’ climate such as in California’s Central Valley, the impact of irrigated agriculture can be large in the dry season but negligible in the wet season due to seasonal variation in surface energy partitioning. Here we report further analysis of regional climate model simulations showing that diurnal variation in the impact of irrigated agriculture on climate similarly reflects variation in surface energy partitioning, as well as smaller changes in net radiation. With conversion of natural vegetation to irrigated agriculture, statistically significant decreases of 4–8?K at 2?m occurred at midday June–September, and small decreases of ~1?K occurred in winter months only in relatively dry years. This corresponded to reduced sensible heat flux of 100–350?W?m?2 and increased latent heat fluxes of 200–450?W?m?2 at the same times and in the same months. We also observed decreases of up to 1,500?m in boundary layer height at midday in summer months, and marginally significant reductions in surface zonal wind speed in July and August at 19:00 PST. The large decrease in daytime temperature due to shifts in energy partitioning overwhelmed any temperature increase related to the reduced zonal sea breeze. Such changes in climate and atmospheric dynamics from conversion to (or away from) irrigated agriculture could have important implications for regional air quality in California’s Central Valley.  相似文献   

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