用数字云图确定热带气旋强度方法的检验和应用          下载免费PDF全文

范蕙君  李修芳 《应用气象学报》1996,7(1):113-117

以关岛飞机探测的热带气旋资料和登陆热带气旋的实测风资料为观测值，将用数字云图确定的热带气旋强度与观测值作比较，其平均绝对误差均不足3 ms-1。文章还给出了1994年业务试用结果。检验结果表明，此方法具有业务应用价值。  相似文献   

A polarized microwave radiative transfer model for passive remote sensing   总被引：1，自引：0，他引：1  

M. Deiveegan  C. Balaji  S.P. Venkateshan 《Atmospheric Research》2008,88(3-4):277-293

The objective of the present work is to develop a general purpose, polarized, microwave radiative transfer forward model, including calculation of interaction parameters for fast, simultaneous and accurate generation of radiances, for use in a wide variety of atmospheric retrieval applications. This complete polarized model includes the generation of atmospheric profiles, calculation of the interaction parameters and the solution of the vector radiative transfer equations. In the present work, the doubling and adding method is used to calculate radiances. Mie theory is used for spherical particles to evaluate the polarized scattering matrix. Two types of sea surface models applicable for specular and diffuse surfaces respectively are implemented. The model has been validated against standard benchmark cases and experimental data available in literature. While the model is itself generic, parametric studies are performed to study the influence of the vertical structure of the atmosphere, for two polarizations and a set of frequencies to be used on the microwave imager aboard the proposed Indo-French climate research satellite MEGHA-TROPIQUES.  相似文献   

雅砻江流域下游梯级水库地震台网监测能力验证   总被引：1，自引：0，他引：1  

褚孝远  韩进  杜瑶  景晟 《华南地震》2015,35(1):57-61

雅砻江流域是中国第三大水电基地,位于强震区,水库地震监测工作十分重要。基于近震震级公式和古登堡-里克特震级频度关系式,分别求取雅砻江下游梯级电站水库诱发地震监测台网的理论监测能力和根据实际记录地震进行监测能力验证。结果表明:在重点监视区理论监测能力达到了ML0.5级的要求,实际观测验证表明,重点监视区其实际最小完整性震级为ML0.5级,达到了雅砻江流域下游梯级水库诱发地震监测台网设计目标。  相似文献   

Long-term SMOS soil moisture products: A comprehensive evaluation across scales and methods in the Duero Basin (Spain)     

《Physics and Chemistry of the Earth》2015

The European Space Agency’s Soil Moisture and Ocean Salinity (SMOS) Level 2 soil moisture and the new L3 product from the Barcelona Expert Center (BEC) were validated from January 2010 to June 2014 using two in situ networks in Spain. The first network is the Soil Moisture Measurement Stations Network of the University of Salamanca (REMEDHUS), which has been extensively used for validating remotely sensed observations of soil moisture. REMEDHUS can be considered a small-scale network that covers a 1300 km² region. The second network is a large-scale network that covers the main part of the Duero Basin (65,000 km²). At an existing meteorological network in the Castilla y Leon region (Inforiego), soil moisture probes were installed in 2012 to provide data until 2014. Comparisons of the temporal series using different strategies (total average, land use, and soil type) as well as using the collocated data at each location were performed. Additionally, spatial correlations on each date were computed for specific days. Finally, an improved version of the Triple Collocation (TC) method, i.e., the Extended Triple Collocation (ETC), was used to compare satellite and in situ soil moisture estimates with outputs of the Soil Water Balance Model Green-Ampt (SWBM-GA). The results of this work showed that SMOS estimates were consistent with in situ measurements in the time series comparisons, with Pearson correlation coefficients (R) and an Agreement Index (AI) higher than 0.8 for the total average and the land-use averages and higher than 0.85 for the soil-texture averages. The results obtained at the Inforiego network showed slightly better results than REMEDHUS, which may be related to the larger scale of the former network. Moreover, the best results were obtained when all networks were jointly considered. In contrast, the spatial matching produced worse results for all the cases studied.These results showed that the recent reprocessing of the L2 products (v5.51) improved the accuracy of soil moisture retrievals such that they are now suitable for developing new L3 products, such as the presented in this work. Additionally, the validation based on comparisons between dense/sparse networks and satellite retrievals at a coarse resolution showed that temporal patterns in the soil moisture are better reproduced than spatial patterns.  相似文献   

Multibody dynamical modeling of the FPSO soft yoke mooring system and prototype validation     

《Applied Ocean Research》2019

The Soft Yoke Mooring System (SYMS) is a single point mooring system for shallow water. It is composed of a mooring framework, mooring legs, yoke, and single point, and is located at the Floating Production Storage and Offloading (FPSO) through 13 hinge joints, such as universal joints and thrust bearings. Mooring restoring force, motions and postures of mooring components, and mechanical behaviors of hinge joints are major criteria for the structural design of the SYMS. Aiming at the difficulties of the multibody dynamics in traditional design of the SYMS, a multi-body dynamic mathematical modeling with seven independent degrees of freedom (DOFs) which is applicable to prototype field engineering was developed in this study. The proposed mathematical modeling of the SYMS multibody dynamic system has several advantages: 1. Internal tribological behaviors in hinge joints are considered within the presented multibody dynamics model to illustrate the good dynamic effects of the SYMS. 2. The multibody dynamic model can be applied in field service. Correctness and feasibility of the proposed multibody dynamic simulation method for describing motions and postures of hinges and single-body were validated by the prototype monitoring data. 3. The horizontal restoring force of the SYMS was calculated according to field measurement data. The motion state of each single body and internal stress distributions at each hinge joint in the SYMS are given. 4. The multibody dynamics calculation program can be directly used for the real-time monitoring of mechanical behaviors of the SYMS under the service state. The simulated results can provide real-time guarantee for safety alarming of the system. The vulnerability of the mooring system in service was evaluated based on long-term monitoring data analysis.  相似文献   

Validation of the hydrologic evaluation of landfill performance (HELP) model for simulating the water balance of cover systems   总被引：4，自引：0，他引：4  

Klaus Berger 《Environmental Geology》2000,39(11):1261-1274

 Simulation models can be efficient tools for several tasks especially in planning. In the USA, the HELP model was developed to simulate the water balance of landfill liner systems, especially of cover systems. HELP version 3 was examined in a German climate in an extensive validation study, and a German adaptation was developed. The validation study consists of three parts: a methodological part (meaning, aims and procedure of validation), a theoretical part (comparison of the modelling approach with the state of science, comparison of documentation, literature and source code), and a practical part (sensitivity analyses and operational validation). In the operational validation, measured and simulated discharges and actual evapotranspiration data of test fields on the landfill Hamburg-Georgswerder from 1988 to 1995 were compared. Limitations, weak points, and errors of the HELP model are shown. The HELP model is a suitable tool for experts in hydrology; but good knowledge of the model and its behaviour and critical review of the simulation results are essential. Received: 14 May 1999 · Accepted: 23 September 1999  相似文献   

Intercomparison and validation of MODIS and GLASS leaf area index (LAI) products over mountain areas: A case study in southwestern China     

《International Journal of Applied Earth Observation and Geoinformation》2017

The validation study of leaf area index (LAI) products over rugged surfaces not only gives additional insights into data quality of LAI products, but deepens understanding of uncertainties regarding land surface process models depended on LAI data over complex terrain. This study evaluated the performance of MODIS and GLASS LAI products using the intercomparison and direct validation methods over southwestern China. The spatio-temporal consistencies, such as the spatial distributions of LAI products and their statistical relationship as a function of topographic indices, time, and vegetation types, respectively, were investigated through intercomparison between MODIS and GLASS products during the period 2011–2013. The accuracies and change ranges of these two products were evaluated against available LAI reference maps over 10 sampling regions which standed for typical vegetation types and topographic gradients in southwestern China.The results show that GLASS LAI exhibits higher percentage of good quality data (i.e. successful retrievals) and smoother temporal profiles than MODIS LAI. The percentage of successful retrievals for MODIS and GLASS is vulnerable to topographic indices, especially to relief amplitude. Besides, the two products do not capture seasonal dynamics of crop, especially in spring over heterogeneously hilly regions. The yearly mean LAI differences between MODIS and GLASS are within ±0.5 for 64.70% of the total retrieval pixels over southwestern China. The spatial distribution of mean differences and temporal profiles of these two products are inclined to be dominated by vegetation types other than topographic indices. The spatial and temporal consistency of these two products is good over most area of grasses/cereal crops; however, it is poor for evergreen broadleaf forest. MODIS presents more reliable change range of LAI than GLASS through comparison with fine resolution reference maps over most of sampling regions. The accuracies of direct validation are obtained for GLASS LAI (r = 0.35, RMSE = 1.72, mean bias = −0.71) and MODIS LAI (r = 0.49, RMSE = 1.75, mean bias = −0.67). GLASS performs similarly to MODIS, but may be marginally inferior to MODIS based on our direct validation results. The validation experience demonstrates the necessity and importance of topographic consideration for LAI estimation over mountain areas. Considerable attention will be paid to the improvements of surface reflectance, retrieval algorithm and land cover types so as to enhance the quality of LAI products in topographically complex terrain.  相似文献   

Validation of the ESA CCI soil moisture product in China     

《International Journal of Applied Earth Observation and Geoinformation》2016

The quality of a newly merged soil moisture product (ECV_SM v0.1) from active and passive microwave sensors has attracted widespread international attention. The performance evaluation of this product will benefit studies on climate, meteorology, agriculture, hydrology, ecology and the environment. In this study, meteorological station data and the Noah soil moisture product were used to validate the ECV_SM product in China. First, some conventional statistical measures, such as correlation coefficients, bias, root mean square difference (RMSD) and mean relative error (MRE), were computed to describe the level of agreement between the meteorological station data and ECV_SM values. The accuracy was moderately high (the correlation was significant at the 0.05 level), although the two datasets differed slightly for various types of land cover. Compared with cropland and urban and built-up areas, the performance of ECV_SM was best in grassland regions. Second, the triple collocation technique was used to assess the random error in the meteorological station data, Noah soil moisture product and ECV_SM product. The mean errors in these three datasets were 0.108, 0.079 and 0.075 m³ m⁻³, respectively, on July 8, 2010 and 0.099, 0.061 and 0.059 m³ m⁻³, respectively, on October 8, 2010. Only two days of data were used for the triple collocation test as a representative, but this cannot precisely indicate that the test results on any other day correspond with the test results on these two days. Additionally, a trend analysis of ECV_SM during 2003–2010 was carried out using the Mann–Kendall trend test.  相似文献   

基于地面观测的遥感监测蒸散量验证方法研究   总被引：3，自引：2，他引：1  

贾贞贞  刘绍民  毛德发  王志良  徐自为  张茹 《地球科学进展》2010,25(11):1248-1260

为了保证遥感监测蒸散量的准确性,需建立一套较完整的遥感监测蒸散量地面验证方法对其进行验证.通过由大孔径闪烁仪、涡动相关仪和自动气象站等组成的蒸散量观测系统可以获取不同卫星像元尺度蒸散量的地面观测值.自2002年以来,由海河流域的密云、馆陶、大兴及小汤山等站构建了一个不同卫星像元尺度蒸散量的观测站网,经过严格的观测数据处理与质量控制,获取了一大批卫星像元尺度蒸散量及其配套参数的地面观测值.同时,建立了一套基于地面观测的遥感监测蒸散量验证流程,重点对验证像元的选取以及评价指标的构建等进行探讨.依据上述验证流程,在海河流域的北京地区开展了遥感监测蒸散量的地面验证工作.利用2008年密云站和大兴站的大孔径闪烁仪观测数据,对基于MODIS数据估算的北京地区区域蒸散量进行验证.结果表明:这套基于大孔径闪烁仪观测数据的遥感监测蒸散量验证方法是合理、可行的.其中2008年北京地区遥感监测月、日蒸散量的均方差分别为13.75和0.91 mm,平均相对误差分别为22.79%、18.61%.  相似文献   

Cellular modelling of river catchments and reaches: Advantages, limitations and prospects   总被引：2，自引：4，他引：2  

T.J. Coulthard  D.M. Hicks  M.J. Van De Wiel 《Geomorphology》2007,90(3-4):192

The last decade has witnessed the development of a series of cellular models that simulate the processes operating within river channels and drive their geomorphic evolution. Their proliferation can be partly attributed to the relative simplicity of cellular models and their ability to address some of the shortcomings of other numerical models. By using relaxed interpretations of the equations determining fluid flow, cellular models allow rapid solutions of water depths and velocities. These can then be used to drive (usually) conventional sediment transport relations to determine erosion and deposition and alter the channel form. The key advance of using these physically based yet simplified approaches is that they allow us to apply models to a range of spatial scales (1–100 km²) and time periods (1–100 years) that are especially relevant to contemporary management and fluvial studies.However, these approaches are not without their limitations and technical problems. This paper reviews the findings of nearly 10 years of research into modelling fluvial systems with cellular techniques, principally focusing on improvements in routing water and how fluvial erosion and deposition (including lateral erosion) are represented. These ideas are illustrated using sample simulations of the River Teifi, Wales. A detailed case study is then presented, demonstrating how cellular models can explore the interactions between vegetation and the morphological dynamics of the braided Waitaki River, New Zealand. Finally, difficulties associated with model validation and the problems, prospects and future issues important to the further development and application of these cellular fluvial models are outlined.  相似文献