Cloud-radiation interaction has a large impact on the Earth＇s weather and climate change, and clouds with different heights cause different radiative forcing. Thus, the information on the statistics of cloud height a...Cloud-radiation interaction has a large impact on the Earth＇s weather and climate change, and clouds with different heights cause different radiative forcing. Thus, the information on the statistics of cloud height and its variation in space and time is very important to global climate change studies. In this paper, cloud top height （CTH）, cloud base height （CBH） and cloud thickness over regions of the Tibetan Plateau, south slope of the plateau and South Asian Monsoon are analyzed based on CloudSat data during the period from June 2006 to December 2007. The results show that frequency of CTH and CBH in unit area over the studied regions have certain temporal-spatial continuity. The CTH and CBH of different cloud types have different variation scopes, and their seasonal variations are distinct. Cloud thickness is large （small） in summer （winter）, and the percentages of different cloud types also have certain regularity.展开更多
Satellite and human visual observation are two of the most important observation approaches for cloud cover. In this study, the total cloud cover （TCC） observed by MODIS onboard the Terra and Aqua satellites was com...Satellite and human visual observation are two of the most important observation approaches for cloud cover. In this study, the total cloud cover （TCC） observed by MODIS onboard the Terra and Aqua satellites was compared with Synop meteorological station observations over the North China Plain and its surrounding regions for 11 years during daytime and 7 years during nighttime. The Synop data were recorded eight times a day at 3-h intervals. Linear interpolation was used to interpolate the Synop data to the MODIS overpass time in order to reduce the temporal deviation between the satellite and Synop observations. Results showed that MODIS-derived TCC had good consistency with the Synop observations; the correlation coefficients ranged from 0.56 in winter to 0.73 in summer for Terra MODIS, and from 0.55 in winter to 0.71 in summer for Aqua MODIS. However, they also had certain differences. On average, the MODIS-derived TCC was 15.16% higher than the Synop data, and this value was higher at nighttime （15.58%-16.64%） than daytime （12.74%-14.14%）. The deviation between the MODIS and Synop TCC had large seasonal variation, being largest in winter （29.53%-31.07%） and smallest in summer （4.46%-6.07%）. Analysis indicated that cloud with low cloud-top height and small cloud optical thickness was more likely to cause observation bias. Besides, an increase in the satellite view zenith angle, aerosol optical depth, or snow cover could lead to positively biased MODIS results, and this affect differed among different cloud types.展开更多
光学遥感影像不可避免会受到云的遮挡,导致影像应用性降低,遥感影像去云是近些年来的热门研究方向。插值算法利用一张或多张影像计算相似像素来重建缺失像素,但是最佳相似像素的确定和地物突变的高精度重建仍存在挑战。文章利用多时相...光学遥感影像不可避免会受到云的遮挡,导致影像应用性降低,遥感影像去云是近些年来的热门研究方向。插值算法利用一张或多张影像计算相似像素来重建缺失像素,但是最佳相似像素的确定和地物突变的高精度重建仍存在挑战。文章利用多时相影像时间相关性关系、空间关系和光谱关系,提出了基于时空谱约束的相似像素插值(SPISTS)的去云方法。该方法利用时域和谱域特征选择相似像素,并通过空间、时间相关性和光谱关系约束求得影像缺失值,最后通过正则化项对预测进行偏差改正。在3个不同地区进行实验并与加权线性回归(weighted linear regression,WLR)、时空加权回归(spatio-temporal weighted regression,STWR)、改进邻域相似像素插值(modified neighborhood similar pixel interpolation,MNSPI)结果进行比较。实验结果表明,该方法精度较高,能够减弱辐射差异带来的影响。展开更多
提出了联合室内空间语义的室内空间运动剖分算法,采用形态学操作提取墙中线,并对墙体对象进行融合优化与拓扑重构,实现了基于激光点云的建筑信息模型(building information modeling, BIM)实体墙对象几何和拓扑重建。以某综合楼三维点...提出了联合室内空间语义的室内空间运动剖分算法,采用形态学操作提取墙中线,并对墙体对象进行融合优化与拓扑重构,实现了基于激光点云的建筑信息模型(building information modeling, BIM)实体墙对象几何和拓扑重建。以某综合楼三维点云为实验数据重建BIM实体墙模型,验证了提出方法的可靠性。展开更多
利用WRF(weather research and forecasting)v3.7.1模式对2010年湖北省冬季一次冻雨积冰过程开展数值研究。研究发现,该次积冰过程中不同阶段的云微物理结构及降水形成的云物理机制相似,均通过过冷暖雨过程形成。利用由WRF模式模拟得到...利用WRF(weather research and forecasting)v3.7.1模式对2010年湖北省冬季一次冻雨积冰过程开展数值研究。研究发现,该次积冰过程中不同阶段的云微物理结构及降水形成的云物理机制相似,均通过过冷暖雨过程形成。利用由WRF模式模拟得到的积冰期间气象场及云降水微物理资料,采用积冰厚度预报模型对该次冻雨过程中积冰厚度的时间变化进行计算。与实际积冰厚度的观测结果对比发现,积冰厚度预报模型可以较好地预报该次过程中电线积冰厚度随时间的发展趋势。展开更多
基金funded by National Natural Science Foundation of China(40830102 and 41205016)
文摘Cloud-radiation interaction has a large impact on the Earth＇s weather and climate change, and clouds with different heights cause different radiative forcing. Thus, the information on the statistics of cloud height and its variation in space and time is very important to global climate change studies. In this paper, cloud top height （CTH）, cloud base height （CBH） and cloud thickness over regions of the Tibetan Plateau, south slope of the plateau and South Asian Monsoon are analyzed based on CloudSat data during the period from June 2006 to December 2007. The results show that frequency of CTH and CBH in unit area over the studied regions have certain temporal-spatial continuity. The CTH and CBH of different cloud types have different variation scopes, and their seasonal variations are distinct. Cloud thickness is large （small） in summer （winter）, and the percentages of different cloud types also have certain regularity.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41590874 and 41590875)the Ministry of Science and Technology of China (Grant No. 2014CB953703)
文摘Satellite and human visual observation are two of the most important observation approaches for cloud cover. In this study, the total cloud cover （TCC） observed by MODIS onboard the Terra and Aqua satellites was compared with Synop meteorological station observations over the North China Plain and its surrounding regions for 11 years during daytime and 7 years during nighttime. The Synop data were recorded eight times a day at 3-h intervals. Linear interpolation was used to interpolate the Synop data to the MODIS overpass time in order to reduce the temporal deviation between the satellite and Synop observations. Results showed that MODIS-derived TCC had good consistency with the Synop observations; the correlation coefficients ranged from 0.56 in winter to 0.73 in summer for Terra MODIS, and from 0.55 in winter to 0.71 in summer for Aqua MODIS. However, they also had certain differences. On average, the MODIS-derived TCC was 15.16% higher than the Synop data, and this value was higher at nighttime （15.58%-16.64%） than daytime （12.74%-14.14%）. The deviation between the MODIS and Synop TCC had large seasonal variation, being largest in winter （29.53%-31.07%） and smallest in summer （4.46%-6.07%）. Analysis indicated that cloud with low cloud-top height and small cloud optical thickness was more likely to cause observation bias. Besides, an increase in the satellite view zenith angle, aerosol optical depth, or snow cover could lead to positively biased MODIS results, and this affect differed among different cloud types.
文摘光学遥感影像不可避免会受到云的遮挡,导致影像应用性降低,遥感影像去云是近些年来的热门研究方向。插值算法利用一张或多张影像计算相似像素来重建缺失像素,但是最佳相似像素的确定和地物突变的高精度重建仍存在挑战。文章利用多时相影像时间相关性关系、空间关系和光谱关系,提出了基于时空谱约束的相似像素插值(SPISTS)的去云方法。该方法利用时域和谱域特征选择相似像素,并通过空间、时间相关性和光谱关系约束求得影像缺失值,最后通过正则化项对预测进行偏差改正。在3个不同地区进行实验并与加权线性回归(weighted linear regression,WLR)、时空加权回归(spatio-temporal weighted regression,STWR)、改进邻域相似像素插值(modified neighborhood similar pixel interpolation,MNSPI)结果进行比较。实验结果表明,该方法精度较高,能够减弱辐射差异带来的影响。
文摘提出了联合室内空间语义的室内空间运动剖分算法,采用形态学操作提取墙中线,并对墙体对象进行融合优化与拓扑重构,实现了基于激光点云的建筑信息模型(building information modeling, BIM)实体墙对象几何和拓扑重建。以某综合楼三维点云为实验数据重建BIM实体墙模型,验证了提出方法的可靠性。
文摘利用WRF(weather research and forecasting)v3.7.1模式对2010年湖北省冬季一次冻雨积冰过程开展数值研究。研究发现,该次积冰过程中不同阶段的云微物理结构及降水形成的云物理机制相似,均通过过冷暖雨过程形成。利用由WRF模式模拟得到的积冰期间气象场及云降水微物理资料,采用积冰厚度预报模型对该次冻雨过程中积冰厚度的时间变化进行计算。与实际积冰厚度的观测结果对比发现,积冰厚度预报模型可以较好地预报该次过程中电线积冰厚度随时间的发展趋势。
