In order to improve the practicality of spectral method and the efficiency of computation, the multi-spectrum method is proposed on the basis of multi-grid method. Coarse spectra are used to compute the slow nonlinear...In order to improve the practicality of spectral method and the efficiency of computation, the multi-spectrum method is proposed on the basis of multi-grid method. Coarse spectra are used to compute the slow nonlinear part (including physical process), while fine spectra are used to compute the fast linear part. This method not only can reduce computation time, but also can obtain computational efficiency similar to that from only fine spectra. Thus, it is an economical numerical method. Both explicit complete-square-conservation scheme and multispectrum scheme are used to improve IAP L 9 T 42 spectral climate models, with and without physical forcings respectively, and the advantage of reducing computation time is obtained satisfactorily. In order to overcome the difficulty that vapor equation is very sensitive to the change of time step, the square-conservation semi-Lagrangian scheme is used to solve vapor equation. Because the semi-Lagrangian scheme has the property of square-conservation, computational instability can be avoided. When time step becomes longer with the semi-Lagrangian Scheme, through numerical examples, the vapor transportation can be depicted objectively and the effect of precipitation simulation can be modified.展开更多
Marine airborne multispectrum scanner （MAMS） onboard the China marine surveillance plane can be used to survey marine environment, resources and disaster and provide the technical support for high-frequency, high-ef...Marine airborne multispectrum scanner （MAMS） onboard the China marine surveillance plane can be used to survey marine environment, resources and disaster and provide the technical support for high-frequency, high-efficiency and high-resolution remote sensing monitoring for the coastal management. MAMS did not have the IMU/POS equipment, so it brought severe challenge for the geometry correction. One airborne geometry correction method is introduced for marine multi- spectrum data without the attitude information. First, it is the coarse geometry correction, which simulates the roll angle and pitch angle of plane according to the ideal flying model; the second step is the precise geometry correction by using the SPOT orthogonal projected data as the reference of registration, based on maximization of alignment metric method. With the validation, relative error of coarse correction is 81.42 m compared with SPOT data, and 11.3 m for precise correction. This method provides the high precision localization information for the oceanic remote sensing and application, and establishes the foundation for monitoring the marine resource and environment.展开更多
为了探究无人机多指标构建叶面积指数(Leaf Area Index,LAI)估算模型的能力,该研究通过不同纹理组合方式优选纹理指数,分别以光谱特征、纹理指数和作物覆盖度作为输入量建立一元线性模型,3类指标结合构建多元逐步回归和人工神经网络模型...为了探究无人机多指标构建叶面积指数(Leaf Area Index,LAI)估算模型的能力,该研究通过不同纹理组合方式优选纹理指数,分别以光谱特征、纹理指数和作物覆盖度作为输入量建立一元线性模型,3类指标结合构建多元逐步回归和人工神经网络模型,分析多指标结合估算LAI的精度。结果表明:新的纹理指数能够明显提高纹理特征值与LAI的相关性,近红外波段均值与蓝波段均值的差值较近红外波段均值提高了13.54%;将绿度归一化植被指数(Green Normalized Difference Vegetation Index,GNDVI)、差值纹理指数和作物覆盖度结合来估算水稻LAI的精度最好,多指标结合的多元逐步回归模型的决定系数为0.866,调整后决定系数为0.816,均方根误差为0.308,人工神经网络模型结果再次验证这一结论。该研究成果可为基于无人机平台估算作物结构参数提供理论依据,并为其他作物LAI估算提供借鉴。展开更多
文摘In order to improve the practicality of spectral method and the efficiency of computation, the multi-spectrum method is proposed on the basis of multi-grid method. Coarse spectra are used to compute the slow nonlinear part (including physical process), while fine spectra are used to compute the fast linear part. This method not only can reduce computation time, but also can obtain computational efficiency similar to that from only fine spectra. Thus, it is an economical numerical method. Both explicit complete-square-conservation scheme and multispectrum scheme are used to improve IAP L 9 T 42 spectral climate models, with and without physical forcings respectively, and the advantage of reducing computation time is obtained satisfactorily. In order to overcome the difficulty that vapor equation is very sensitive to the change of time step, the square-conservation semi-Lagrangian scheme is used to solve vapor equation. Because the semi-Lagrangian scheme has the property of square-conservation, computational instability can be avoided. When time step becomes longer with the semi-Lagrangian Scheme, through numerical examples, the vapor transportation can be depicted objectively and the effect of precipitation simulation can be modified.
基金The Scientific Research Fund of the Second Institute of Oceanography,State Oceanic Administration of China under contract No.JG1016Special Funds for Scientific Research on Public Cause of China from Ministry of Finance under contract No.200805028
文摘Marine airborne multispectrum scanner （MAMS） onboard the China marine surveillance plane can be used to survey marine environment, resources and disaster and provide the technical support for high-frequency, high-efficiency and high-resolution remote sensing monitoring for the coastal management. MAMS did not have the IMU/POS equipment, so it brought severe challenge for the geometry correction. One airborne geometry correction method is introduced for marine multi- spectrum data without the attitude information. First, it is the coarse geometry correction, which simulates the roll angle and pitch angle of plane according to the ideal flying model; the second step is the precise geometry correction by using the SPOT orthogonal projected data as the reference of registration, based on maximization of alignment metric method. With the validation, relative error of coarse correction is 81.42 m compared with SPOT data, and 11.3 m for precise correction. This method provides the high precision localization information for the oceanic remote sensing and application, and establishes the foundation for monitoring the marine resource and environment.
