土地利用类型转换对地表能量平衡和气候的影响——基于SiB2模型的模拟结果

利用SiB2 模型对中国东北地区农田、草地和森林3 种土地利用类型的地表能量平衡过程展开研究,分析不同土地利用类型对生物地球物理参数（反照率和粗糙度）、能量平衡（净辐射、潜热和显热）和气候（冠层温度）的影响。结果表明：①模型模拟的地表能量平衡与实测数据的年变化动态相似（R²>0.42）,差值保持在±30 W/m²,温度在±4 ℃。②利用相同气象数据模拟不同土地利用类型通过生物地球物理过程对地表能量平衡和气候的影响,发现森林吸收的净辐射最高且主要用于潜热分配,农田的净辐射最低且主要用于显热分配,草地净辐射和能量分配居中。③生态系统获得的净辐射主要受反照率的影响,净辐射分配受叶面积指数的调节。④冠层温度（℃）受反照率和净辐射在潜热和显热间分配的相对重要性的影响：年平均值为森林（7.7）>农田（7.64）>草地（6.67）。⑤降水对模拟结果有显著影响,是森林模拟差异的主要原因。在不同土地利用类型中,降水增加土壤水分,净辐射更多分配到潜热,较少分配到显热,降低冠层温度。     

Sparse Randomized Maximum Likelihood (SpRML) for subsurface flow model calibration and uncertainty quantification

Despite their apparent high dimensionality, spatially distributed hydraulic properties of geologic formations can often be compactly (sparsely) described in a properly designed basis. Hence, the estimation of high-dimensional subsurface flow properties from dynamic performance and monitoring data can be formulated and solved as a sparse reconstruction inverse problem. Recent advances in statistical signal processing, formalized under the compressed sensing paradigm, provide important guidelines on formulating and solving sparse inverse problems, primarily for linear models and using a deterministic framework. Given the uncertainty in describing subsurface physical properties, even after integration of the dynamic data, it is important to develop a practical sparse Bayesian inversion approach to enable uncertainty quantification. In this paper, we use sparse geologic dictionaries to compactly represent uncertain subsurface flow properties and develop a practical sparse Bayesian method for effective data integration and uncertainty quantification. The multi-Gaussian assumption that is widely used in classical probabilistic inverse theory is not appropriate for representing sparse prior models. Following the results presented by the compressed sensing paradigm, the Laplace (or double exponential) probability distribution is found to be more suitable for representing sparse parameters. However, combining Laplace priors with the frequently used Gaussian likelihood functions leads to neither a Laplace nor a Gaussian posterior distribution, which complicates the analytical characterization of the posterior. Here, we first express the form of the Maximum A-Posteriori (MAP) estimate for Laplace priors and then use the Monte-Carlo-based Randomize Maximum Likelihood (RML) method to generate approximate samples from the posterior distribution. The proposed Sparse RML (SpRML) approximate sampling approach can be used to assess the uncertainty in the calibrated model with a relatively modest computational complexity. We demonstrate the suitability and effectiveness of the SpRML formulation using a series of numerical experiments of two-phase flow systems in both Gaussian and non-Gaussian property distributions in petroleum reservoirs and successfully apply the method to an adapted version of the PUNQ-S3 benchmark reservoir model.     

河道糙率系数变化对全新世古洪水流量计算的影响研究

洪水流量计算中河道糙率是一个重要的灵敏度参数。以汉江上游郧县尚家河台地前沿记录的四期古洪水流量计算为例,研究河道糙率系数在比降-面积法和HEC-RAS模型中对古洪水流量计算结果的影响。结果表明：其他水文参数一定时,河道糙率系数以±15%变幅,比降-面积法重建的古洪水流量变幅在-13.04%～17.65%,HEC-RAS模型计算的流量变幅在-4.32%～4.57%;若河道糙率系数以±25%变幅,比降-面积法和HEC-RAS模型计算的流量变幅分别为-20%～33.33%和-7.79%～9.18%,说明采用HEC-RAS模型重建古洪水流量,可减少河道糙率系数对计算结果的影响,使古洪水流量计算结果更为可靠。此外,假定其他参数不变,主河槽和左、右岸糙率系数依次变幅±25%,主河槽糙率系数变化对流量计算结果影响最大,说明洪水流量计算时应准确选取主河槽的糙率系数。该结果对水利工程建设具有重要的现实意义。     

旅游目的地形象与目的地感知吸引力关系——以厦门市为例

为明确目的地形象的细分维度与目的地感知吸引力的关系,以厦门市为例,基于问卷调查,利用Logistic回归模型实证研究认知形象、情感形象、总体形象对目的地感知吸引力的影响。结果表明：1）目的地品牌、自然和文化2个认知形象因子对目的地感知吸引力有显著正向影响,休闲娱乐和接待环境2个认知形象因子对目的地感知吸引力没有显著正向影响;2）情感形象、总体形象对目的地感知吸引力皆有显著正向影响;3）情感形象对目的地感知吸引力的影响大于认知形象对目的地感知吸引力的影响。     

Copper bioavailability and toxicity to Mytilus galloprovincialis in Shelter Island Yacht Basin,San Diego,CA

The bioavailability and toxicity of copper (Cu) in Shelter Island Yacht Basin (SIYB), San Diego, CA, USA, was assessed with simultaneous toxicological, chemical, and modeling approaches. Toxicological measurements included laboratory toxicity testing with Mytilus galloprovincialis (Mediterranean mussel) embryos added to both site water (ambient) and site water spiked with multiple Cu concentrations. Chemical assessment of ambient samples included total and dissolved Cu concentrations, and Cu complexation capacity measurements. Modeling was based on chemical speciation and predictions of bioavailability and toxicity using a marine Biotic Ligand Model (BLM). Cumulatively, these methods assessed the natural buffering capacity of Cu in SIYB during singular wet and dry season sampling events. Overall, the three approaches suggested negligible bioavailability, and isolated observed or predicted toxicity, despite an observed gradient of increasing Cu concentration, both horizontally and vertically within the water body, exceeding current water quality criteria for saltwater.     

Low-Level Wind Forecast over the La Plata River Region with a Mesoscale Boundary-Layer Model Forced by Regional Operational Forecasts

A mesoscale boundary-layer model (BLM) is used for running 12-h low-level wind forecasts for the La Plata River region. Several experiments are performed with different boundary conditions that include operational forecasts of the Eta/CPTEC model, local observations, as well as a combination of both. The BLM wind forecasts are compared to the surface wind observations of five weather stations during the period November 2003–April 2004. Two accuracy measures are used: the hit rate or percentage of cases with agreement in the wind direction sector, and the root-mean-squared error (RMSE) of the horizontal wind components. The BLM surface wind forecasts are always more accurate, since its averaged hit rate is three times greater and its averaged RMSE is one half smaller than the Eta forecasts. Despite the large errors in the surface winds displayed by the Eta forecasts, its 850 hPa winds and surface temperature forecasts are able to drive the BLM model to obtain surface winds forecasts with smaller errors than the Eta model. An additional experiment demonstrates that the advantage of using the BLM model for forecasting low-level winds over the La Plata River region is the result of a more appropriate definition of the land–river surface temperature contrast. The particular formulation that the BLM model has for the geometry of the river coasts is fundamental for resolving the smaller scale details of the low-level local circulation. The main conclusion of the study is that operational low-level wind forecasts for the La Plata River region can be improved by running the BLM model forced by the Eta operational forecasts. L. Sraibman and G. J. Berri—Members of Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) of Argentina. An erratum to this article can be found at     

模式气候吸引子信息约束下的动力协调初始化方法及其在ENSO预测中的应用

为了改善模式初始场质量,减少初值与模式不协调对ENSO预测的影响,针对国家气候中心NCCo海-气耦合模式原初始化方案动力小协调的问题,从利用模式长期耦合模拟资料中的模式气候吸引子信息的角度出发,发展了一种获取观测资料中与模式相协调分量的信息重构方法,提出了一种模式气候吸引子信息约束下的动力协调初始化方案.对该方案回报检验的结果表明:通过反演NCCo海-气耦合模式模拟资料中的模式气候吸引子信息,有助于获取观测资料中与模式相协调的信息分量特征,实现了初始化过程中动力模式与所同化观测资料间的协调.这种基于信息重构方法的动力协调初始化方案,既可以延续原初始化方案利用观测信息较多的优势,又克服了原方案中观测资料和动力模式不协调的缺陷.这种新的初始化方案,消除了观测资料和模式不协调在初始场中产生的小尺度高频噪声,突出了与NCCo模式动力特征相适应的ENSO尺度信息.进而抑制了初始场中高频噪声所引起的快变预报误差的增长,提高了模式的预测技巧.     

青岛奥帆赛高分辨率数值模式系统研制与应用

该文初步建立了青岛奥帆赛高分辨率数值模式系统（包括预报模式和释用模式）。预报模式基于Weather Research & Forecast（WRF）模式V3.0,模式设计为网格数60×50×38,水平分辨率500 m。在IBM小型机上用8个线程作15 h预报所需机时约为1 h 20 min,可满足实时业务预报需要。利用高分辨率边界层模式和城市小区尺度模式对该预报结果进行了动力释用（水平分辨率分别为100 m和10 m）。该模式系统于2008年夏季进行了实时运行试验,模式产品在北京奥运气象服务中心青岛分中心使用。结果表明:该模式系统有较强的稳定性和实用性,对城市热岛、海陆风、地形及建筑物影响等局地环流特征有较好的模拟效果。数值试验分析表明:城市化引起城市热岛效应,增大了海陆温差,使海风加强;城市建筑物拖曳作用使风速减小,从而使海风推进速度减缓;精细下垫面资料的引入对海风等局地环流高分辨率数值模拟至关重要。     

土壤质地对中国区域陆面过程模拟的影响

利用陆面过程模式(CLM3.5)和中国区域两种土壤质地数据(分别来自第二次中国土壤调查SNSS和联合国粮食农业组织FAO),研究了土壤质地变化对于模式模拟的陆表水热变量的影响。结果显示,土壤质地对土壤水文学变量的影响远大于对土壤热力学变量的影响,尤其是对于饱和土壤含水量和饱和水力传导率的影响。对于模式的输出,土壤质地影响比较明显的有土壤湿度、总径流和土壤渗透等水文学变量以及地表潜热、地表感热和土壤热通量等热力学变量,而影响相对较小的有地面吸收的太阳辐射和地表反照率。同时,发现基于SNSS模拟的土壤湿度与站点观测值更加接近。因此,本研究认为基于SNSS土壤质地数据可以有效地改进模式模拟结果,建议以后在陆面模式试验中尽可能使用以观测为基础的SNSS土壤质地数据。     

下垫面非均匀流域的幂指数TOPMODEL的模拟研究

利用取消流域土壤表层饱和导水率0K、土壤饱和导水率有效衰减系数m和地下水补给速率R为空间均匀假设的幂指数TOPMODEL,对流域水量平衡各分量进行敏感性研究试验,揭示空间非均匀性对幂指数TOPMODEL模拟结果的影响。从特定研究流域所得结果中可得的主要结论有:1)0K、m和R的空间变化对流域的逐日地表径流和基流以及逐日总径流有影响,针对设定的0K、m和R的空间变化,其中m的空间变化较明显地增加了逐日地表径流和洪峰流量。2)就设定的0K、m和R的空间变化而论,对流域多年平均年总径流以及蒸发模拟结果影响不大,但改变了径流在地表径流和基流之间的分配;其中R的空间变化影响最显著,m和0K的空间变化影响则较小。