Preliminary Assessment of the Common Land Model Coupled with the IAP Dynamic Global Vegetation Model          下载免费PDF全文

ZHU Jia-Wen  ZENG Xiao-Dong  LI Fang  SONG Xiang 《大气和海洋科学快报》2014,7(6):505-509

The Common Land Model（CoLM） was coupled with the IAP Dynamic Global Vegetation Model（IAPDGVM）, and the performance of this combined CoLMIAP model was evaluated. Offline simulations using both the original Common Land Model（CoLM-LPJ） and CoLM-IAP were conducted. The CoLM-IAP coupled model showed a significant improvement over CoLMLPJ, as the deciduous tree distribution decreased over temperate and boreal regions, while the distribution of evergreen trees increased over the tropics. Some biases in CoLM-LPJ were preserved, including the overestimation of evergreen trees in tropical savanna, the underestimation of boreal evergreen trees, and the absence of boreal shrubs. However, most of these biases did not exist in a further coupled simulation of IAP-DGVM with the Community Land Model（CLM）, for which the parameters of IAP-DGVM were optimized. This implies that further improvement is needed to deal with the differences between CoLM and CLM in parameterizations of landbased physical and biochemical processes.  相似文献   

基于随机集合的非传统型有效波极值模型   总被引：1，自引：0，他引：1  

ZHANG Yi  LAM Jasmine Siu Lee 《海洋学报(英文版)》2014,33(7):125-130

The analysis and design of offshore structures necessitates the consideration of wave loads. Realistic modeling of wave loads is particularly important to ensure reliable performance of these structures. Among the available methods for the modeling of the extreme significant wave height on a statistical basis, the peak over threshold method has attracted most attention. This method employs Poisson process to character- ize time-varying properties in the parameters of an extreme value distribution. In this paper, the peak over threshold method is reviewed and extended to account for subjectivity in the modeling. The freedom in selecting the threshold and the time span to separate extremes from the original time series data is incorpo- rated as imprecision in the model. This leads to an extension from random variables to random sets in the probabilistic model for the extreme significant wave height. The extended model is also applied to different periods of the sampled data to evaluate the significance of the climatic conditions on the uncertainties of the parameters.  相似文献   

面向对象的连云港海岸带土地利用变化及驱动力分析   总被引：2，自引：0，他引：2  

高祥伟  费鲜芸  韩兵 《海洋科学》2014,38(4):81-87

以连云港海岸带为研究区,基于1978年和2010年两期Landsat影像,提取土地利用信息,分析土地利用特征及其动态变化过程;面向土地利用变化基本单元,进行土地利用变化驱动力分析。结果表明:研究期初,该地区的主要土地类型为耕地和盐田,共占研究区面积的67.14%;32 a间共有37.17%的土地发生了变化,盐田和耕地面积快速减少,水产养殖区和工矿企业用地快速增加,有限的林地资源在减少,滩涂围垦达面积46.55 km2,土地利用程度加深;变化的土地中,38.95%由经济结构调整驱动,发展潜力大;27.75%由政策驱动,存在诸多的社会和生态问题;20.49%由政策或者经济结构调整与生产力水平共同驱动,取得较好经济和社会效益;12.81%的土地由政策、人口及经济发展共同驱动。连云港海岸带土地利用存在诸多不足之处,也具有巨大的发展空间。本研究对连云港市提高土地利用的社会效益和生态效益具有重要意义。  相似文献   

基于ENVI 的唐山湾三岛土地利用遥感分类方法的比较分析   总被引：1，自引：0，他引：1  

付佳  黄海军  杨曦光 《海洋科学》2014,38(1):20-26

对唐山湾三岛2010年10月10 m分辨率的SPOT5多光谱数据源,采用不同分类方法进行识别和判断,并对比不同分类器在遥感影像分类中的应用效果和分类精度。有针对性地探究海岛土地利用遥感分类过程中不同方法的优劣,获取最适于岛陆地区土地利用的遥感分类方法。根据土地利用现状分类标准(GB/T21010-2007)和海岛陆域土地利用类型划分的相关规定,将唐山湾三岛主要分为滩涂、裸地、林地、草地、居住区、内陆水体和潮间带(潮水覆盖区)6类。并分别构建结合人为控制的非监督分类、监督分类和基于专家知识的决策树分类系统,参照更高分辨率影像、先验知识和野外调查资料,评价分类结果与实地调查结果的吻合程度,最终通过总体分类精度和Kappa系数等指标对各分类器精度进行评价和对比分析。  相似文献   

城市热岛和海风环流相互作用的数值模拟研究进展   总被引：8，自引：1，他引：7  

苗峻峰 《南京气象学院学报》2014,(4):521-528

在沿海城市地区,城市热岛环流和海风环流往往同时存在;它们在空气污染物的传输和扩散中均起至关重要的作用,对强对流天气亦有重要的触发作用.随着城市化的发展,空气污染等环境问题变得越来越严峻,突然性强对流天气所造成的灾害也越来越严重.因此,沿海城市地区城市热岛和海风环流相互作用的研究受到日益广泛的关注.本文回顾了近30 a来国内外关于城市热岛和海风环流相互作用数值模拟的研究历史,分析了目前的研究现状及存在的一些问题,概述了城市化、城市热岛对海风环流的影响,海风对城市热岛、城市热岛环流的影响,以及城市热岛环流和海风环流的耦合效应.最后,本文提出了一些有待于研究或需深入研究的问题;这些问题的研究将有助于进一步揭示沿海城市地区空气污染动力学机制、强对流天气触发机制.  相似文献   

利用时空信息的单波段地表温度遥感反演     

陈峰  赵小锋  全元  柳林 《遥感学报》2014,18(3):657-672

地表温度被认为是影响生态系统的关键因子之一,它与许多地表过程有关。目前,热红外卫星遥感技术是获取有关区域和全球尺度地表温度信息的一个有效、可行的手段。针对不同卫星上搭载的热红外传感器,许多学者开展了大量的研究,其中针对单波段热红外的特点(如Landsat TM/ETM+,CBERS和HJ-1B)提出了单通道(或单窗)算法。该类算法需要准确的地表比辐射率和大气参数(如大气水分含量)。这些参数在现实中又很难轻易获得,从而在一定程度上限制了现有算法的应用。针对HJ-1B高回访频率的特点,本文提出了利用多时相影像的时空信息来直接反演地表温度的Multi-Temporal and Spatial Information-Based Single Channel(MTSC),以解决现有算法对地表比辐射率和大气参数的过度依赖性。实例分析结果显示,基于MTSC法由HJ-1B反演得到的地表温度结果与MODIS地表(陆表和海表)温度产品具有很好的空间一致性;HJ-1B的陆表温度结果总体上被高估了约1 K,而海表温度结果总体上被高估了0.5 K;同时,MTSC法得到的HJ-1B地表温度结果具有更好的细节和空间完整性。最后,通过分析和讨论指出了一些可能的完善途径,如相似像元的确定、修改优化求解中的目标函数、参数的自适应初始化等,以便提高MTSC法的反演精度和实用性。  相似文献   

An Overview of BCC Climate System Model Development and Application for Climate Change Studies          下载免费PDF全文

WU Tongwen  SONG Lianchun  LI Weiping  WANG Zaizhi  ZHANG Hu  XIN Xiaoge  ZHANG Yanwu  ZHANG Li  LI Jianglong  WU Fanghu  LIU Yiming  ZHANG Fang  SHI Xueli  CHU Min  ZHANG Jie  FANG Yongjie  WANG Fang  LU Yixiong  LIU Xiangwen  WEI Min  LIU Qianxi  ZHOU Wenyan  DONG Min  ZHAO Qigeng  JI Jinjun  Laurent LI  ZHOU Mingyu 《Acta Meteorologica Sinica》2014,28(1):34-56

This paper reviews recent progress in the development of the Beijing Climate Center Climate System Model(BCC-CSM) and its four component models(atmosphere,land surface,ocean,and sea ice).Two recent versions are described:BCC-CSM1.1 with coarse resolution(approximately 2.8125°×2.8125°) and BCC-CSM1.1(m) with moderate resolution(approximately 1.125°×1.125°).Both versions are fully coupled climate-carbon cycle models that simulate the global terrestrial and oceanic carbon cycles and include dynamic vegetation.Both models well simulate the concentration and temporal evolution of atmospheric CO_2 during the 20th century with anthropogenic CO2 emissions prescribed.Simulations using these two versions of the BCC-CSM model have been contributed to the Coupled Model Intercomparison Project phase five(CMIP5) in support of the Intergovernmental Panel on Climate Change(IPCC) Fifth Assessment Report(AR5).These simulations are available for use by both national and international communities for investigating global climate change and for future climate projections.Simulations of the 20th century climate using BCC-CSMl.l and BCC-CSMl.l(m) are presented and validated,with particular focus on the spatial pattern and seasonal evolution of precipitation and surface air temperature on global and continental scales.Simulations of climate during the last millennium and projections of climate change during the next century are also presented and discussed.Both BCC-CSMl.l and BCC-CSMl.l(m) perform well when compared with other CMIP5 models.Preliminary analyses indicate that the higher resolution in BCC-CSM1.1(m) improves the simulation of mean climate relative to BCC-CSMl.l,particularly on regional scales.  相似文献   

The Observed and Simulated Major Summer Climate Features in Northwest China and Their Sensitivity to Land Surface Processes          下载免费PDF全文

LI Qian  XUE Yongkang 《Acta Meteorologica Sinica》2014,28(5):836-848

Northwest China （NWC） is a typical arid and semi-arid region. In this study, the main summer climate features over NWC are presented and the performance of an atmospheric general circulation model （NCEP GCM/SSiB） over this region is evaluated. Satellite-derived vegetation products are applied in the model. Based on comparison with observational data and Reanalysis II data, the model generally captures major features of the NWC summer energy balance and circulation. These features include： a high surface tem- perature center dominating the planetary boundary layer; widespread descending motion; an anticyclone （cyclone） located in the lower and middle （upper） troposphere, covering most parts of central NWC; and the precipitation located mainly in the high elevation areas surrounding NWC.
The sensitivity of the summer energy balance and circulation over NWC and surrounding regions to land surface processes is assessed with specified land cover change. In the sensitivity experiment, the degradation over most parts of NWC, except the Taklimakan desert, decreases the surface-absorbed radiation and leads to weaker surface thermal effects. In northern Xinjiang and surrounding regions, less latent heating causes stronger anomalous lower-level anticyclonic circulation and upper-level cyclonic circulation, leading to less summer precipitation and higher surface temperature. Meanwhile, the dry conditions in the Hexi Corridor produce less change in the latent heat flux. The circulation change to the north of this area plays a domi- nant role in indirectly changing lower-level cyclonic conditions, producing more convergence, weaker vertical descending motion, and thus an increase in the precipitation over this region.  相似文献   

Statistical Characteristics of Convective Initiation in the Beijing-Tianjin Region Revealed by Six-Year Radar Data          下载免费PDF全文

WANG Yu  HAN Lei  WANG Hongqing 《Acta Meteorologica Sinica》2014,28(6):1127-1136

Characteristics of convective initiation (CI) in the Beijing-Tianjin region during the warm season of2008-2013 are examined. A total of 38877 CI cases are identified by a thunderstorm identification, tracking, analysis, and nowcasting algorithm. CI cases are evaluated in the context of associated terrain, weather systems, and land cover properties. The spatial distribution of all CI cases shows that there are dense CI activities around the 200-m elevation, which means that convective storms are more easily triggered over foothills. From 1500-1800 to 0300-0600 BT (Beijing Time), the high-occurrence CI region tends to propagate southeastward (i.e., from mountains to plains, then to ocean). Among the four local weather systems, the Mongolian cold vortex has the highest CI frequency while the after-trough system has the lowest CI frequency. For the land cover relationships with CI, the urban land cover has the highest CI density and the forest-type land cover has the second highest CI density; these two types of land cover are more conducive to CI formation.  相似文献   

基于人工蜂群CA模型的南京市土地利用变化模拟与预测     

吴掠桅  刘耿 《测绘通报》2022,(2):95-99

以南京市为例,构建人工蜂群元胞自动机（CA_ABC）模型,对2000—2007年的土地利用变化进行模拟以实现CA_ABC模型的校正,并以2007—2015年的土地利用变化为案例,验证该模型的有效性。模拟结果总体精度（OA）2007年为87.79%,2015年为80.61%;模拟结果的品质因数（FOM）2007年为21.23%,2015年为19.25%。基于CA_ABC模型和马尔可夫链预测未来城市土地总量,对南京市2025和2035年的土地利用格局进行了预测,对城市扩张和生态用地被侵占现象进行分析。模型预测结果表明,未来20年的城市扩张主要以牺牲耕地和林地为代价,2025和2035年80%的城市扩张面积来源于对耕地面积的侵占,17%的城市面积扩张是由2015年的林地转换得到的。研究表明,准确模拟、预测未来城市格局及评估城市扩张能够对生态用地侵占,以及为决策者合理规划城市、推动城市可持续发展提供帮助。  相似文献