Theoretical study of partial frequency redistribution function in irradiated, moving atmospheres of close binary components

We have studied the effects of partial frequency redistribution function with angle-averaged   R _II-A  in irradiated and moving atmospheres of close binary components. We have considered the atmospheric extension of the primary component to be twice the radius of the primary component in a close binary system. We have considered two cases: (i) when the atmosphere is at rest and (ii) when the atmosphere is moving. In both the cases, we have computed the line profiles along the line of sight for a given optical depth. The irradiation from the secondary component is assumed to be one, five and 10 times the self-radiation. The line fluxes in the line of sight are calculated by using the total source functions due to self-radiation of the primary component and due to the irradiation from the secondary component. We have noted double-peaked emission lines in the case of a static medium and a reduction of emission peaks in the case of velocity field.     

热带深对流云砧数值模拟及云凝结核数浓度对其影响的初步试验

利用中国科学院大气物理研究所发展的三维强风暴模式,对Egrett Microphysics Experiment with Radiation Lidar and Dynamics（EMERALD）试验期间的一次长寿命热带深对流个例进行对流产生、发展、消亡过程以及云砧的数值模拟,并与实测资料［包括C波段双线偏振雷达图像资料、机载云粒子成像仪（CPI）探测的云砧卷云微物理特性以及激光雷达探测的云砧宏观特性资料］进行了细致的对比,然后通过改变模式中最大云滴数浓度进行有关云凝结核数浓度影响云砧卷云冰晶含水量和数浓度的敏感性试验。模式较好地模拟出系统的一些重要宏观特征,如爆发性增长阶段、各高度雷达水平反射率因子的最大值、对流云主体移动方向、云砧底部和顶部高度。对云砧冰相粒子含水量、数浓度以及平均直径等微观特征的模拟结果与实测也比较接近。对于本文个例而言,异质核化为冰晶形成的最主要方式,其次为过冷云滴的均质核化。敏感性试验结果表明:当云凝结核数浓度增加时,爆发性增长阶段的垂直速度减小,使得对流云从中低层向高层的水物质输送量减少,从而使云砧卷云冰晶的数量减少。     

三维激光扫描技术在危岩体变形监测中的应用

提出了一种基于三维激光扫描技术的高危岩体表面变形监测方法。该方法首先计算第一期点云数据参考点的法向量,并基于此点的法向量构建圆柱体;然后在圆柱体内计算第二期点云数据的区域重心,以此作为危岩体表面两期或多期变形比较的依据。将该方法应用于重庆武隆-南川地区鸡冠岭危岩体的变形监测与分析,获得了初步满意的结果。     

利用MODIS和CERES遥感数据研究青藏高原的云辐射强迫效应

准确估算青藏高原的云辐射效应,对分析该地区的近地面感热通量十分重要.本文首先利用加权平均方法,分别将中分辨率成像光谱仪(MODIS)、测云雷达(CPR)和云与地球辐射能量系统(CERES)的像元数据进行融合.利用这些数据,分析了青藏高原上多云个例(2017年5月5日)与少云个例(2017年8月2日)情况下的可见光通道和...     

Validation of WRF model on simulating forcing data for Heihe River Basin

The research of coupling WRF (Weather Research and Forecasting Model) with a land surface model is enhanced to explore the interaction of the atmosphere and land surface; however, regional applicability of WRF model is questioned. In order to do the validation of WRF model on simulating forcing data for the Heihe River Basin, daily meteorological observation data from 15 stations of CMA (China Meteorological Administration) and hourly meteorological observation data from seven sites of WATER (Watershed Airborne Telemetry Experimental Research) are used to compare with WRF simulations, with a time range of a whole year for 2008. Results show that the average MBE (Mean Bias Error) of daily 2-m surface temperature, surface pressure, 2-m relative humidity and 10-m wind speed were ?0.19 °C, ?4.49 hPa, 4.08% and 0.92 m/s, the average RMSE (Root Mean Square Error) of them were 2.11 °C, 5.37 hPa, 9.55% and 1.73 m/s, and the average R (correlation coefficient) of them were 0.99, 0.98, 0.80 and 0.55, respectively. The average MBE of hourly 2-m surface temperature, surface pressure, 2-m relative humidity, 10-m wind speed, downward shortwave radiation and downward longwave were ?0.16 °C, ?6.62 hPa, ?5.14%, 0.26 m/s, 33.0 W/m² and ?6.44 W/m², the average RMSE of them were 2.62 °C, 17.10 hPa, 20.71%, 2.46 m/s, 152.9 W/m² and 53.5 W/m², and the average R of them were 0.96, 0.97, 0.70, 0.26, 0.91 and 0.60, respectively. Thus, the following conclusions were obtained: (1) regardless of daily or hourly validation, WRF model simulations of 2-m surface temperature, surface pressure and relative humidity are more reliable, especially for 2-m surface air temperature and surface pressure, the values of MBE were small and R were more than 0.96; (2) the WRF simulating downward shortwave radiation was relatively good, the average R between WRF simulation and hourly observation data was above 0.9, and the average R of downward longwave radiation was 0.6; (3) both wind speed and rainfall simulated from WRF model did not agree well with observation data.     

Insights into Convective-scale Predictability in East China: Error Growth Dynamics and Associated Impact on Precipitation of Warm-Season Convective Events

This study investigated the regime-dependent predictability using convective-scale ensemble forecasts initialized with different initial condition perturbations in the Yangtze and Huai River basin(YHRB) of East China. The scale-dependent error growth(ensemble variability) and associated impact on precipitation forecasts(precipitation uncertainties) were quantitatively explored for 13 warm-season convective events that were categorized in terms of strong forcing and weak forcing. The forecast err...     

分类线性回归的Landsat影像去云方法

首先,对参考影像和待去云影像上的云覆盖区域进行检测和掩膜;然后,对掩膜后的参考影像进行ISODATA聚类,并建立各个类别参考影像到待去云影像灰度值的线性回归方程;再对待去云影像上的云覆盖区域,依据参考影像上的灰度值进行最小距离方法分类,划分到聚类形成的各个类别之中;最后,依据各个类别回归方程进行灰度值预测。实验结果表明,所提方法能够进行云区的检测和去除,预测精度相比传统方法有较大提高。     

高分辨率遥感图像厚云检测算法

针对高空间分辨率多光谱图像,设计了一种基于缨帽变换、数据正则化以及多尺度光谱分析技术的多尺度循环检测算法。实验结果表明:对于Landsat-7 ETM+图像,其检测精度与基于热波段的自动化云量估计算法相近,但优于传统的直接分类方法(最大似然分类与ISODATA分类)。由于该算法无需借助热波段及其他辅助数据,因而在实现高分辨率图像厚云掩膜的高效与高精度提取方面具有很高的应用潜力。     

一种基于平面拟合的LIDAR点云滤波方法

LIDAR点云滤波是将LIDAR点云数据中的地面点和非地面点分离的过程。根据在较小区域内可以近似认为地面为一平面,本文提出了一种应用平面拟合的方法,首先在一个局部区域内拟合出一个近似平面,通过判断LIDAR点是否属于该平面来获取平面点,并通过分类处理从平面点中得到地面点,最后用得到的地面点内插出DEM。滤波前,需要剔除高程异常点,本文应用了高程差约束算法抑制高程异常点,从而较好地保持了原始数据的局部细节信息。     

一种改进的空间上下文点云分类方法

考虑到点云数据具有线性分布和密度不均匀的特点,以及现有复杂场景点云分类方法中缺少对非局部空间上下文信息的有效利用,提出了一种改进的空间上下文点云分类方法。该方法在提取点云数据顾及曲率的自适应邻域的基础上,首先估算点云局部特征与依赖性空间上下文,并基于超级体素提取分布性空间上下文,最后采用高阶条件随机场模型,实现对点云数据的自动分类,避免了利用单一点云局部特征分类的局限性。试验结果表明,本文方法能够有效提高点云数据地物分类精度。