基于机器学习的海洋环境预报订正方法研究     

许立兵  王安喜  汪纯阳  陈悦  陈昱文  周峥  陈幸荣  邢建勇  刘克威  黄小猛 《海洋通报》2020,39(6):695-704

结合中尺度数值模式 WRF 预报数据和 ERA5 再分析资料,利用机器学习方法对 WRF 预报场的风场、温度、气压进行预报订正。采用 ERA5 作为真值,与原始 WRF 预报相比,利用随机森林模型可以将预报结果整体均方根误差降低 44%以 上,利用深度神经网络模型可以将预报结果整体均方根误差降低 34%以上。通过随机森林模型实验得到不同输入特征对预报要素的影响程度,分析了关键的预报订正因子。  相似文献   

复杂城区车载激光扫描点云分层路段定位与数据纠正实验研究     

王胜利  郝国建  蒋毅  孙磊  杨红军 《测绘工程》2021,30(2):26-31

高精度的车载点云数据是实现各种城市地物要素提取的前提,但在复杂城市环境下车载作业时信号遮挡、衰减和多径效应频繁发生,进而造成点云数据精度严重降低,如何对复杂环境下的点云数据进行分析和纠正就显得至关重要.现有的质量分析方法多从测距误差、仪器安装误差和数据处理误差方面出发,虽然可以在一定程度上改化数据,但在如何快速定位出分...  相似文献   

微波照射下火成岩升温特性和升温预测模型研究     

赵沁华  赵晓豹  赵建新  刘汉文  郑彦龙  李建春  何磊  何举龙  余家旺 《高校地质学报》2021,27(1):94-101

微波辅助破岩可有效降低刀具磨损,提高破岩效率,具有广阔的发展前景.文章选取了10种火成岩进行微波加热试验,发现岩石的升温速率主要与岩石所含矿物的种类、含量,及岩石中的Fe元素含量有关.岩石所含矿物越敏感、含量越多,岩石中的Fe元素含量越大时,其升温速率越高.整体而言,火成岩中基性岩的升温速率最高、中性岩次之、酸性岩最低...  相似文献   

Curvature derived from LiDAR digital elevation models as simple indicators of debris-flow susceptibility     

Atsuko NONOMURA  Shuichi HASEGAWA  Hideo MATSUMOTO  Mari TAKAHASHI  Mina MASUMOTO  Kazuhito FUJISAWA 《山地科学学报》2019,(1):95-107

To mitigate the damage caused by debris flows resulting from heavy precipitation and to aid in evacuation plan preparation, areas at risk should be mapped on a scale appropriate for affected individuals and communities. We tested the effectiveness of simply identifying debris-flow hazards through automated derivation of surface curvatures using LiDAR digital elevation models. We achieved useful correspondence between plan curvatures and areas of existing debris-flow damage in two localities in Japan using the analysis of digital elevation models(DEMs). We found that plan curvatures derived from 10 m DEMs may be useful to indicate areas that are susceptible to debris flow in mountainous areas. In residential areas located on gentle sloping debris flow fans, the greatest damage to houses was found to be located in the elongated depressions that are connected to mountain stream valleys. Plan curvaturederived from 5 m DEM was the most sensitive indicators for susceptibility to debris flows.  相似文献   

近60a来新疆不同海拔气候变化的时空特征分析   总被引：1，自引：0，他引：1       下载免费PDF全文

张音  古丽贤·吐尔逊拜  苏里坦  刘迁迁 《干旱区地理》2019,42(4):822-829

全球变暖是当前全球气候变化研究的热点之一,新疆深居亚欧大陆内陆,地形气候复杂,探讨该区域气候变化与海拔的关系对全球气候变化研究具有重要的参考意义。基于1958—2017年新疆41个气象站的月和年平均气候数据,采用一元线性回归、Mann Kendall（M-K）趋势分析和突变检验等方法分析该地区气候变化的时空分布与海拔的关系。结果表明：1958—2017年新疆年均气温、年均降水量均呈上升趋势,但增加幅度具有时间和空间差异。在时间上,北疆四季平均气温增温幅度均大于南疆（冬季除外）,四季降水量增幅北疆大于南疆（夏季除外）;在空间上,北疆气温和降水的增幅均大于南疆。研究区各个站点气温呈现出南部高而北部低的空间格局,年均降水量北部多,南部低。各个站点气温倾向率总体随海拔增加而减少,年均降水量变化率随海拔升高而增加,在不同海拔带内部存在差异。综上所述,受全球气候变暖的影响,近60 a来新疆年均气温和年均降水量均呈上升趋势,尤其是北疆对全球气候变暖的响应较为敏感。  相似文献   

椭球谐和球谐系数之间一个简单的转换关系     

梁磊  于锦海  万晓云 《测绘学报》2019,48(2):185-190

本文推导的椭球谐系数和球谐系数相互之间转换关系的核心思想是在ε~2量级下利用Legendre函数的正交性,从球谐系数求解的积分表示出发,将积分中的椭球坐标变量与球坐标变量相互转换,从而得出椭球谐系数与球谐系数之间的转换关系。本文导出的转换关系有以下优点:①对于第二类Legendre函数的计算采用Laurent级数表示,使计算第二类Legendre函数更为简单;②保留了ε~2量级下,导出的转换关系相比文献[2]的形式更简单,满足物理大地测量边值问题线性化的要求;③顾及了余纬和归化余纬的区别。  相似文献   

How forest gaps shaped plant diversity along an elevational gradient in Wolong National Nature Reserve?     

Chen  Li  Han  Wangya  Liu  Dan  Liu  Guohua 《地理学报(英文版)》2019,29(7):1081-1097

Journal of Geographical Sciences - Understanding the underlying ecological processes that control plant diversity within (α-diversity) and among (β-diversity) forest gaps is important for...  相似文献   

Parallelization of the flow-path network model using a particle-set strategy     

Fangli Zhang 《International journal of geographical information science》2019,33(10):1984-2010

High-performance simulation of flow dynamics remains a major challenge in the use of physical-based, fully distributed hydrologic models. Parallel computing has been widely used to overcome efficiency limitation by partitioning a basin into sub-basins and executing calculations among multiple processors. However, existing partition-based parallelization strategies are still hampered by the dependency between inter-connected sub-basins. This study proposed a particle-set strategy to parallelize the flow-path network (FPN) model for achieving higher performance in the simulation of flow dynamics. The FPN model replaced the hydrological calculations on sub-basins with the movements of water packages along the upstream and downstream flow paths. Unlike previous partition-based task decomposition approaches, the proposed particle-set strategy decomposes the computational workload by randomly allocating runoff particles to concurrent computing processors. Simulation experiments of the flow routing process were undertaken to validate the developed particle-set FPN model. The outcomes of hourly outlet discharges were compared with field gauged records, and up to 128 computing processors were tested to explore its speedup capability in parallel computing. The experimental results showed that the proposed framework can achieve similar prediction accuracy and parallel efficiency to that of the Triangulated Irregular Network (TIN)-based Real-Time Integrated Basin Simulator (tRIBS).  相似文献   

Current-induced scour beneath initially elevated subsea pipelines     

《Applied Ocean Research》2019

When a subsea pipeline is laid on an uneven seabed, certain sections may have an initial elevation with respect to the far-field seabed, e_o, and thus potentially affecting the on-bottom stability of the pipeline. This paper focuses on quantifying the effects of the upstream dimensionless seabed shear stress, θ_∞, and Reynolds number, Re, on: (1) the maximum dimensionless seabed shear stress beneath the pipe, θ_max, to be compared to the critical shear stress in order to determine whether scour would occur and progress towards an equilibrium state; and, (2) the dimensionless equilibrium scour depth beneath the pipe, S_eq/D. Using a 2-D Reynolds averaged Navier-Stokes (RANS) approach along with the k-ω Shear Stress Transport (SST) turbulence model, a parametric study involving 243 computational fluid dynamics (CFD) simulations was conducted. The simulation results were used to develop a closed-form equation for the prediction of θ_max. Subsequently, experimental measurements of S_eq/D have been compiled from published literature, to develop a new closed-form equation for the prediction of S_eq/D with a high correlation to the experimental data. In summary, we present two closed-form equations for the prediction of θ_max and S_eq/D for pipelines with an initial e_o/D, which are applicable for both clear-water and live-bed conditions. The effects of θ_∞ and Re have been included, albeit Re having a small influence as compared to the other parameters.  相似文献   

Jason-2高度计电离层GIM误差分析及修正研究     

黄霞凤  苗洪利  苗翔鹰  薛文文 《海洋学报》2019,41(7):143-148

基于Jason-2高度计2015年地球物理数据集(GDR)38个周期太平洋海域的全球电离层图(GIM)电离层校正值和双频校正值的数据,分不同季度和不同纬度区域比较二者的差异,结果表明:GIM值与双频校正值之间存在明显的差异,GIM校正值普遍高于双频校正值,说明GIM高估了电离层路径延迟,GIM校正值与双频校正值的差异与季节和纬度区间有关。用梯度下降法得到GIM值的修正方程,将修正方程应用于2016年Jason-2的全年数据,修正后的GIM值与双频校正值十分接近,在各年份中均具有良好的适用性。在单频高度计不能使用电离层双频校正算法的情况下,可以利用不同季度和不同纬度区域的修正方程对同等高度的高度计GIM值进行修正以达到双频校正值的精度水平。  相似文献