项目名称: 逐阶优化的快速蒙特卡罗三维云大气辐射传输模式研究
项目编号: No.41305032
项目类型: 青年科学基金项目
立项/批准年度: 2014
项目学科: 天文学、地球科学
项目作者: 王震
作者单位: 南京信息工程大学
项目金额: 25万元
中文摘要: 针对蒙特卡罗三维云大气辐射传输模式在遥感反演应用中的数值计算效率瓶颈,本项目拟采用理论推导和数值模拟方法,开展逐阶优化的快速模拟方法的研究。首先由相函数截断基本原则推求最优截断相函数数学表达式及其随粒子变化的参数,优化中高阶散射的数值模拟过程,继而通过数值模拟试验揭示中低阶散射局部估计量巨大方差的形成机制,验证接近探测器方向的低阶后向散射引起局部估计量巨大方差的假设,由此利用稀有事件重点抽样理论建立逐阶优化的探测器方向重点抽样方法,自适应地避免中低阶散射大局部估计量的出现,进而提高数值效率。最终建立一个快速有效的蒙特卡罗三维云大气辐射传输模式,准确模拟各种真实而复杂的云大气和地表条件下的辐射场分布,为遥感反演三维云大气微物理特性提供快速准确的正演模式支持。
中文关键词: 云;相函数;蒙特卡罗;辐射传输;MSCART
英文摘要: Due to the numerical inefficiency in Monte Carlo radiative transfer in 3D cloudy atmosphere, this project intends to carry out the research in the successive-order scattering optimization methods for fast simulation by theoretical inference and numerical simulation. Firstly we will deduce the mathematical expression of the optimized truncated phase functions and calculate the parameters varying with the particles to optimize the high-order scattering simulation in accordance with the principles of the phase function truncation approximations, then reveal the occurrence laws of the huge variance of local estimation in the low-order scattering simulations using numerical simulation tests and verify the assumptions that the huge variance is produced by the low-order scattering events where the scattering directions near detector directions, thereby develop the successive-order optimized detector directional importance sampling methods using the rare event important sampling theory to avoid producing the huge variance of the local estimation and then improve numerical efficiency. Lastly the project will develop one fast and efficient Monte Carlo radiative transfer model for the highly accurate radiance estimate in realistic and complex cloudy atmosphere over various surfaces to provide the fast and accurate forward
英文关键词: cloud;phase function;Monte Carlo;radiative transfer;MSCART