Cloud removal for remotely sensed images by similar pixel replacement guided with a spatio-temporal MRF model     

《ISPRS Journal of Photogrammetry and Remote Sensing》2014

Cloud cover is generally present in remotely sensed images, which limits the potential of the images for ground information extraction. Therefore, removing the clouds and recovering the ground information for the cloud-contaminated images is often necessary in many applications. In this paper, an effective method based on similar pixel replacement is developed to solve this task. A missing pixel is filled using an appropriate similar pixel within the remaining region of the target image. A multitemporal image is used as the guidance to locate the similar pixels. A pixel-offset based spatio-temporal Markov random fields (MRF) global function is built to find the most suitable similar pixel. The proposed method was tested on MODIS and Landsat images and their land surface temperature products, and the experiments verify that the proposed method can achieve highly accurate results and is effective at dealing with the obvious atmospheric and seasonal differences between multitemporal images.  相似文献   

Climatology,trend of aerosol-cloud parameters and their correlation over the Northern Indian Ocean     

《地学前缘(英文版)》2023,14(4):101563

Aerosols are one of the important atmospheric constituents and exert indirect impact on climate through the modification of microphysical and radiative properties of clouds that in turn perturb the precipitation pattern. Thus, the long term quantification of changes in aerosol and cloud characteristics and their interactions on both temporal as well as spatial scale will provide a crucial information for the better assessment of future climate change. In present study, 18 years (2003–2020) MODerate Resolution Imaging Spectro-radiometer (MODIS) derived aerosol-cloud dataset over the Northern Indian Ocean (NIO) were analysed to assess climatology and trend of aerosol, cloud characteristics and their correlation. We found a strong heterogeneity in spatio-temporal variation of aerosol and cloud parameters over the NIO that are more prominent for the coastal region. The climatological mean of aerosol loading is found high (AOD ≥ 0.5) over the outflow region along the Indian sub-continent and low (AOD ≤ 0.2) over the northern equatorial open ocean. The climatological mean of cloud properties shows dominance of optically thicker deep convective (CTP < 600 hPa and CTT < 260 K) clouds over the southern Bay of Bengal (BoB) and thinner shallow (CTP > 700 hPa and CTT > 273 K) over the northwestern Arabian Sea (AS). Similarly, bigger effective radii (>17 µm) observed along the equatorial open ocean whereas smaller CER (<17 µm) were found over Indian sub-continental coastline and western AS. Further, trend analysis reveals an increasing pattern in AOD (0.002 yr^?1), CER (0.051 µm yr^?1), LWP (0.033 gm^?2 yr^?1) and CF (0.002 yr^?1) while COD, CTT and CTP show negative trend in order of ?0.005 yr^?1, ?0.094 K yr^?1 and ?1.160 hPa yr^?1, respectively. We also perform similar analysis for seven sub-region of interest (R1 to R7) across the NIO and results show a decreasing pattern in AOD (?0.001 yr^?1) at R4 against maximum mean AOD (0.44 ± 0.03). However, coastal sub-regions R1 and R5 illustrate maximum increase in aerosol loading (>0.003 yr^?1) suggesting a significant impact of sub-continental outflow over the regions. The spatial correlation of cloud properties with respect to AOD shows a positive slope for CER (0.14) and CF (0.48) and a negative for COD (?0.19), LWP (?0.18), CTT (?0.37), CTP (?0.41). The present study provides in-depth information about the aerosol-cloud characteristics for a long term scale over NIO and could be useful in regional aerosol-cloud interaction induced climate forcing estimation.  相似文献   

黄山冬半年云海预报研究     

丁国香  刘安平  杨彬 《气象与环境学报》2019,(2):97-101

利用2004—2014年黄山气象站地面气象观测资料和NCEP/NCAR再分析资料,分析了云海发生时气温、气压、湿度、风速等要素的垂直分布、时间演变特征,选取能够反映云海天气特征的指标作为预报因子,分析预报因子分布特征,确定其阈值及消空指标,采用指标叠套法建立了黄山冬半年各月08时云海预报模型,总体正确率为88%,T_S评分为31%。利用2015—2016年资料进行检验,总体正确率为88%,T_S评分为36%,其中3月、10月T_S评分为44%,1月T_S评分为38%,模拟结果对黄山冬半年的云海预报具有一定的参考价值。  相似文献   

CMIP6云反馈模式比较计划（CFMIP）概况与评述     

李立娟  郭准 《气候变化研究进展》2019,15(5):465-468

世界气候研究计划(WCRP)于2003年支持开展云反馈模式比较计划（CFMIP)。目前已经开展到第三阶段（CFMIP-3)。相比前两阶段的试验,CFMIP-3试验设计更加丰富、具体,除增加CMIP6 DECK和Historical试验的观测模拟器（COSP）输出外,还围绕着回答7个云反馈相关的科学问题,设计了Tier-1（必做）和Tier-2（可选）两类试验。CFMIP将气候模拟、观测研究和过程模拟等几个研究方向更紧密地联系在一起,并为理解和模拟云及其辐射反馈的气候贡献提供更深刻的认识和分析手段。  相似文献   

New orbits for comets C/1843 J1 (Mauvais) and C/1853 W1 (van Arsdale)     

R. L. Branham 《Astronomische Nachrichten》2015,336(10):955-960

New orbits for comet C/1843 J1 (Mauvais) and comet C/1853 W1 (van Arsdale) are calculated. Both orbits are hyperbolic, with e = 1.001145 and semi‐major axis a = –1412.18 AU for Mauvais and e = 1.000700 and a = –2919.24 AU for van Arsdale. Integrating the orbits backwards indicate that both comets were born in the far Oort cloud. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

云GIS多层次服务体系     

吴勤书  朱月霞  王会娜  王玮 《测绘科学》2015,(8):28-32

针对现有云GIS服务模式不能满足用户需求的不足,该文提出一套完整的云GIS"四层一端"多层次服务体系,包括云GIS Service、Server、基础设施与虚拟数据中心四层服务和一个云服务管理端。详细阐述了每一层服务的能力和内容,使用户更深入地理解、更便捷地使用云端各种服务。在此基础上进行了应用实证研究,将其应用于江苏省地理信息公共服务平台建设,成功地构建了"测绘·云"GIS平台,可以面向不同用户需求提供不同层级的云服务。最后分析了该文构建的多层次服务体系的主要特点。  相似文献   

一次典型层积云的飞机观测结果及与卫星资料的对比分析   总被引：1，自引：0，他引：1  

赵增亮  毛节泰  王磊  魏强  韩志刚  李成才 《气象学报》2011,69(3):521-527

飞机探测可直接获取云的微观结构特征量,但只是一些线段;卫星遥感资料可大范围监测云环境,但不是直接获得云参量,需要反演。因而开展云的飞机观测结果与卫星资料的对比分析是必要的。对1999月6月4日华北平原上一次层积云过程两个架次的飞机微物理探测资料进行了详细分析,并将飞机盘旋上升和下降取得的5次云参数垂直探测结果作为辐射传输模式SBDART2.4的输入,采取正演的方式与GMS5/VISSR、NOAA15/AVHRR反射通道的资料进行了对比分析。飞机探测显示层积云云厚约1000 m,云粒子浓度最大值425 cm-3,含水量最大值0.2 g/m3。第1架次云粒子浓度、含水量、有效半径的平均值为225±75 cm-3、0.08±0.03 g/m3、7.2±1.6μm,第2架次云粒子浓度、含水量、有效半径的平均值为196±73 cm-3、0.04±0.02 g/m3、4.9±1.4μm。按500 m垂直分层后,云粒子有效半径平均值为6.1±1.7μm,主体云层(1000—1500 m)柱含水量平均值为29.5±17.5 g/m2。敏感性试验表明当有云存在时,云的光学厚度是影响可见光通道反照率的主要因子,利用飞机探测云参数...  相似文献   

一次层状云降水过程云粒子的特征分析     

李义宇  李培仁  封秋娟 《山西气象》2011,(3):34-38,46

本文针对山西省2009年6月18日-19日的一次降水过程,利用Micaps系统天气图和机载DMT探测资料分析了这次降水的宏微观特征,并用Г分布拟合了云滴谱分布,结果接近云滴谱的实际分布。  相似文献   

新疆两次暴雪过程云系的MODIS三光谱特征分析   总被引：4，自引：3，他引：1  

王蕾  黄慰军  黄镇  黄刚  何亚萍 《气象科学》2011,31(1):107-112

针对暴雪云团卫星遥感监测的迫切性与特殊性,利用EOS/MODIS卫星具有较大范围、较高时空分辨率、多通道的遥感探测优势,选取新疆哈密2005年11月18-20日和库车2006年11月22-24日两次暴雪过程,通过研究,得到了MODIS各通道的积雪、晴空、薄卷云等光谱特征,采用可见光、近红外通道剔除与主体云系无关的信息,...  相似文献   

最小二乘支持向量机在云量预报中的应用   总被引：2，自引：2，他引：0  

胡邦辉  刘丹军  王学忠  高传智 《气象科学》2011,31(2):187-193

基于2003-2006年逐年1、8月WRF区域数值预报产品和单站观测资料,采用最小二乘支持向量机回归方法,结合选取合适的参数和核函数,分别按月通过不同长度样本序列建立了台北和厦门站总云量和低云量短期释用预报模型,利用2007年1、8月样本资料对模型进行了预报和检验,并与神经网络方法进行了对比.结果表明:最小二乘支持向量机回归方法的预报效果要好于神经网络方法;两站不同长度样本的总云量和低云量预报模型,预报效果较好,其预报准确率不会因为训练样本的减少而降低.可见,最小二乘支持向量机回归在云量等气象要素释用预报方面,具有较好的应用前景.  相似文献