Observations of high level of ozone at Qinghai Lake basin in the northeastern Qinghai-Tibetan Plateau,western China   总被引：2，自引：0，他引：2  

Q. Y. Wang  R. S. Gao  J. J. Cao  J. P. Schwarz  D. W. Fahey  Z. X. Shen  T. F. Hu  P. Wang  X. B. Xu  R. -J. Huang 《Journal of Atmospheric Chemistry》2015,72(1):19-26

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Evaluation of CMIP5 Climate Models in Simulating 1979–2005 Oceanic Latent Heat Flux over the Pacific     

Ning Cao  Baohua Ren  Jianqiu Zheng 《大气科学进展》2015,32(12):1603-1616

The climatological mean state,seasonal variation and long-term upward trend of 1979–2005 latent heat flux(LHF) in historical runs of 14 coupled general circulation models from CMIP5(Coupled Model Intercomparison Project Phase 5) are evaluated against OAFlux(Objectively Analyzed air–sea Fluxes) data. Inter-model diversity of these models in simulating the annual mean climatological LHF is discussed. Results show that the models can capture the climatological LHF fairly well,but the amplitudes are generally overestimated. Model-simulated seasonal variations of LHF match well with observations with overestimated amplitudes. The possible origins of these biases are wind speed biases in the CMIP5 models. Inter-model diversity analysis shows that the overall stronger or weaker LHF over the tropical and subtropical Pacific region,and the meridional variability of LHF,are the two most notable diversities of the CMIP5 models. Regression analysis indicates that the inter-model diversity may come from the diversity of simulated SST and near-surface atmospheric specific humidity.Comparing the observed long-term upward trend,the trends of LHF and wind speed are largely underestimated,while trends of SST and air specific humidity are grossly overestimated,which may be the origins of the model biases in reproducing the trend of LHF.  相似文献   

利用三维点云数据计算单木树冠体积的扇形分割算法     

李宏星  欧阳玉华  汪海洪 《测绘地理信息》2021,46(6):101-103

基于切片法提出了利用三维点云数据计算树冠体积的扇形分割算法,该方法能更好地顾及树冠轮廓形状.通过实例验证了方法的有效性,结果表明该方法计算的树冠体积值介于凸包法和体元法之间,有效克服了凸包法结果偏大和体元法结果偏小的问题.  相似文献   

闽赣交界桃溪穹隆与外围印支期花岗岩岩石地球化学特征对比及地质意义     

黄昌旗  张开毕  曹明志  王林昌  王峰  赵举兴 《福建地质》2022,41(1):12-25

以桃溪穹隆与外围印支期花岗岩为研究对象,认为桃溪穹隆花岗岩更具壳源特征,表现为与壳源物质有关的矿物较多,岩石呈酸性和碱性程度更高,桃溪穹隆花岗岩高场强元素的亏损程度和亲石元素富集程度都大于穹隆外围,桃溪穹隆花岗岩δEu的亏损程度远大于穹隆外围.Sr-Yb元素特征还显示,印支时期地壳部分重熔形成花岗岩时,桃溪穹隆应处于地...  相似文献   

Dynamic changes in urban land spatial inequality under the core-periphery structure in urban agglomerations     

FANG Xiaoqian  SU Dan  WU Qing  WANG Jiayi  ZHANG Yangjian  LI Guoyu  CAO Yu 《地理学报(英文版)》2023,33(4):760-778

Relatively coordinated development among cities can typically promote the integration of the whole urban agglomeration, while urbanization of land has been found important to economic development in developing countries. Numerous studies have measured the urban land expansion in urban agglomerations. However, urban land spatial inequality under a specific spatial structure remains poorly understood. Here, we combined the β-convergence model and the core-periphery structure to explore the dynamic...  相似文献   

Change of Soil Organic Carbon after Cropland Afforestation in ′Beijing-Tianjin Sandstorm Source Control′ Program Area in China   总被引：2，自引：1，他引：1  

ZENG Xinhua  ;ZHANG Wanjun  ;LIU Xiuping  ;CAO Jiansheng  ;SHEN Huitao  ;ZHAO Xin  ;ZHANG Nan-nan  ;BAI Yuru  ;Yi Mei 《中国地理科学(英文版)》2014,24(4):461-470

Land use change is one of the major factors that affect soil organic carbon(SOC) variation and global carbon balance. However, the effects of land use change on SOC are always variable. In this study, using a series of paired-field experiments, we estimated the effects of revegetation types and environmental conditions on SOC stock and vertical distribution after replacement of cropland with poplar(Populus tomentosa) and korshinsk peashrub(Caragana korshinskii) in three climate regions(Chifeng City, Fengning City and Datong City of the ′Beijing-Tianjin Sandstorm Source Control′(BTSSC) program area. The results show that SOC sequestration rate ranges from 0.15 Mg/(ha·yr) to 3.76 Mg/(ha·yr) in the soil layer of 0–100 cm in early stage after cropland afforestation in the BTSSC program area. The SOC accumulation rates are the highest in Fengning for both the two vegetation types. Compared to C. korshinskii, P. tomentosa has greater effects on SOC accumulation in the three climate regions, but significantly greater effect only appears in Datong. The SOC density increases by 20%–111% and 15%–59% for P. tomentosa and 9%–63% and 0–73% for C. korshinskii in the 0–20 cm and 20–100 cm soil layers, respectively. Our results indicate that cropland afforestation not only affects SOC stock in the topsoil, but also has some effects on subsoil carbon. However, the effect of cropland afforestation on SOC accumulation varied with climate regions and revegetation types. Considering the large area of revegetation and relatively high SOC accumulation rate, SOC sequestration in the BTSSC program should contribute significantly to decrease the CO2 concentration in the atmosphere.  相似文献   

江西省国土资源厅数据灾备系统建设实践     

操屹  徐世亮 《国土资源信息化》2014,(4):20-24

随着江西省国土资源信息化建设的不断深入,国土资源数据积累不断丰富,对数据存储系统有更高的需求,建设一套高性能、高安全性、高可靠性、可扩展性的集中存储系统,实现数据的本地灾备和异地容灾成为信息化建设的当务之急。鉴于此,江西省国土资源厅采用数据镜像、数据备份和连续数据保护（CDP）等技术,开展厅数据中心的灾备系统建设,并进行了系统演练,效果良好。  相似文献   

Albedo enhancement of marine clouds to counteract global warming: impacts on the hydrological cycle     

G. Bala  Ken Caldeira  Rama Nemani  Long Cao  George Ban-Weiss  Ho-Jeong Shin 《Climate Dynamics》2011,37(5-6):915-931

Recent studies have shown that changes in solar radiation affect the hydrological cycle more strongly than equivalent CO₂ changes for the same change in global mean surface temperature. Thus, solar radiation management ??geoengineering?? proposals to completely offset global mean temperature increases by reducing the amount of absorbed sunlight might be expected to slow the global water cycle and reduce runoff over land. However, proposed countering of global warming by increasing the albedo of marine clouds would reduce surface solar radiation only over the oceans. Here, for an idealized scenario, we analyze the response of temperature and the hydrological cycle to increased reflection by clouds over the ocean using an atmospheric general circulation model coupled to a mixed layer ocean model. When cloud droplets are reduced in size over all oceans uniformly to offset the temperature increase from a doubling of atmospheric CO₂, the global-mean precipitation and evaporation decreases by about 1.3% but runoff over land increases by 7.5% primarily due to increases over tropical land. In the model, more reflective marine clouds cool the atmospheric column over ocean. The result is a sinking motion over oceans and upward motion over land. We attribute the increased runoff over land to this increased upward motion over land when marine clouds are made more reflective. Our results suggest that, in contrast to other proposals to increase planetary albedo, offsetting mean global warming by reducing marine cloud droplet size does not necessarily lead to a drying, on average, of the continents. However, we note that the changes in precipitation, evaporation and P-E are dominated by small but significant areas, and given the highly idealized nature of this study, a more thorough and broader assessment would be required for proposals of altering marine cloud properties on a large scale.  相似文献   

石家庄市霜冻期的气候异常特征分析   总被引：4，自引：0，他引：4  

杨荣珍  朱伟军  岳艳霞  曹春丽 《气象与减灾研究》2011,34(2):67-70

基于1955-2009年逐日最低气温资料,采用线性倾向估计法和异常霜冻指标,分析了石家庄市霜冻期的年际和年代际气候异常特征.结果表明,从气候平均上来看,石家庄市初霜冻日为11月7日,终霜冻日为3月21日,无霜冻期为230d;石家庄市特早初霜冻发生频率为5%,偏早初霜冻发生频率16%,特晚终霜冻发生频率为4%,偏晚终霜冻...  相似文献   

Sorption of heavy oil onto Jiaozhou Bay sediment     

Cao X  Yang G  Wei S  Han H 《Marine pollution bulletin》2011,62(4):741-746

The sorption of heavy oil onto sediment collected from Jiaozhou Bay was studied in a series of kinetic and equilibrium experiments using NaCl solutions. The effects of temperature, salinity, and pH of the medium on sorption behavior were investigated.Sorption equilibrium of the heavy oil and sediment was established within 60 min. The process was shown to follow a pseudo-second-order kinetic rate model. The sorption rate decreased with increasing initial heavy oil concentration in the solution. Batch equilibrium experiments showed that the sorption isotherm could be described by the Freundlich model. The standard free energy change and enthalpy change at the temperatures studied (283, 288, 293, and 298 K) were negative. These findings indicated that the process was spontaneous and exothermic. Salinity, pH and temperature influenced sorption performance. Sorption was favored by higher concentrations of NaCl, by lower pH values and by lower temperatures.  相似文献