利用ICESat数据确定格陵兰冰盖高程和体积变化   总被引：1，自引：0，他引：1       下载免费PDF全文

陈国栋  张胜军 《地球物理学报》2019,62(7):2417-2428

两极冰盖消融是造成海平面上升的重要原因，作为世界第二大冰盖，格陵兰冰盖消融速度在进入21世纪以后明显加快，引起了广泛关注.本文利用ICESat卫星激光测高数据，探讨了坡度改正的方法，通过改进平差模型解决了病态问题，并采用重复轨道方法计算了2003年9月至2009年10月间格陵兰冰盖的体积和高程变化趋势，对格陵兰冰盖各冰川流域系统的变化情况进行了详细分析.结果表明，格陵兰冰盖在这6年间平均高程变化趋势为-16.79±0.84 cm·a^-1，体积变化速率为-301.37±15.16 km³·a^-1，体积流失主要发生在冰盖边缘，其中DS1、DS8等流域的体积损失正在加剧，而高程在2000 m以上的冰盖内陆地区表现出高程积聚的状态，但增长速度明显减缓.与现有研究成果的对比表明，算法优化后的本文结果更具可靠性.  相似文献   

一种卫星重力梯度数据的ARMA最优滤波模型构建方法          下载免费PDF全文

朱广彬  常晓涛  付兴科  瞿庆亮 《地球物理学报》2018,61(12):4729-4736

由于卫星重力梯度观测的有色噪声特性和海量观测特征，在利用直接法进行重力场模型的最小二乘求解时，观测值的协方差阵为超大型的非对角阵，这给数值求解带来了极大困难.本文提出了一种基于先验误差功率谱密度的最优ARMA滤波模型构建方法，结合法方程的分块求解策略，可实现对卫星重力梯度观测值的高效滤波处理.数值仿真结果表明，利用最优ARMA滤波器进行时域滤波后，法方程的态性得到了明显改善，重力梯度观测值中的有色噪声得到了有效的"白化"处理，大地水准面精度得到了显著提升.  相似文献   

Inter-comparison of remote sensing platforms for height estimation of mango and avocado tree crowns     

《International Journal of Applied Earth Observation and Geoinformation》2020

To support the adoption of precision agricultural practices in horticultural tree crops, prior research has investigated the relationship between crop vigour (height, canopy density, health) as measured by remote sensing technologies, to fruit quality, yield and pruning requirements. However, few studies have compared the accuracy of different remote sensing technologies for the estimation of tree height. In this study, we evaluated the accuracy, flexibility, aerial coverage and limitations of five techniques to measure the height of two types of horticultural tree crops, mango and avocado trees. Canopy height estimates from Terrestrial Laser Scanning (TLS) were used as a reference dataset against height estimates from Airborne Laser Scanning (ALS) data, WorldView-3 (WV-3) stereo imagery, Unmanned Aerial Vehicle (UAV) based RGB and multi-spectral imagery, and field measurements. Overall, imagery obtained from the UAV platform were found to provide tree height measurement comparable to that from the TLS (R² = 0.89, RMSE = 0.19 m and rRMSE = 5.37 % for mango trees; R² = 0.81, RMSE = 0.42 m and rRMSE = 4.75 % for avocado trees), although coverage area is limited to 1–10 km² due to battery life and line-of-sight flight regulations. The ALS data also achieved reasonable accuracy for both mango and avocado trees (R² = 0.67, RMSE = 0.24 m and rRMSE = 7.39 % for mango trees; R² = 0.63, RMSE = 0.43 m and rRMSE = 5.04 % for avocado trees), providing both optimal point density and flight altitude, and therefore offers an effective platform for large areas (10 km²–100 km²). However, cost and availability of ALS data is a consideration. WV-3 stereo imagery produced the lowest accuracies for both tree crops (R² = 0.50, RMSE = 0.84 m and rRMSE = 32.64 % for mango trees; R² = 0.45, RMSE = 0.74 m and rRMSE = 8.51 % for avocado trees) when compared to other remote sensing platforms, but may still present a viable option due to cost and commercial availability when large area coverage is required. This research provides industries and growers with valuable information on how to select the most appropriate approach and the optimal parameters for each remote sensing platform to assess canopy height for mango and avocado trees.  相似文献   

利用海洋重力场变化分析洋底板块运动          下载免费PDF全文

李倩倩  鲍李峰  C. K. Shum 《地球物理学报》2020,63(7):2506-2515

洋底板块运动是地球动力学和全球变化研究的重要内容.本文根据质量迁移与地球外部重力场变化的对应关系,利用不同时期测高资料推算的1995—2019全球海洋重力场变化结果,反演分析全球洋底板块运动特征.研究表明,板块汇聚边界、板块内无震海岭、海山群、断裂带等区域重力异常变化显著,而在板块离散边界无明显变化趋势;西南印度洋中脊、大西洋中脊、中印度洋中脊等地区重力异常垂直梯度变化显著,且在西太平洋俯冲带、部分海岭区域也存在明显变化,其空间分布与地形基本吻合.海洋重力场变化整体上准确反映了全球洋底板块构造运动.相较于重力异常变化反演结果,重力垂直梯度的变化能够更为准确地反映洋底板块运动特征,特别是在洋中脊区域,扩张速率越小,垂直重力梯度变化越显著.此外,详细讨论了测高海洋重力场不确定因素对洋底板块运动分析结果的影响,海面坡度改正是主要因素之一.  相似文献   

Satellite image analysis using crowdsourcing data for collaborative mapping: current and opportunities     

Wei Su  Xiaodong Zhang 《International Journal of Digital Earth》2020,13(6):645-660

ABSTRACT

Researchers are continually finding new applications of satellite images because of the growing number of high-resolution images with wide spatial coverage. However, the cost of these images is sometimes high, and their temporal resolution is relatively coarse. Crowdsourcing is an increasingly common source of data that takes advantage of local stakeholder knowledge and that provides a higher frequency of data. The complementarity of these two data sources suggests there is great potential for mutually beneficial integration. Unfortunately, there are still important gaps in crowdsourced satellite image analysis by means of crowdsourcing in areas such as land cover classification and emergency management. In this paper, we summarize recent efforts, and discuss the challenges and prospects of satellite image analysis for geospatial applications using crowdsourcing. Crowdsourcing can be used to improve satellite image analysis and satellite images can be used to organize crowdsourced efforts for collaborative mapping.  相似文献   

Detection of spatio-temporal evolutions on multi-annual satellite image time series: A clustering based approach     

《International Journal of Applied Earth Observation and Geoinformation》2019

The expansion of satellite technologies makes remote sensing data abundantly available. While the access to such data is no longer an issue, the analysis of this kind of data is still challenging and time consuming. In this paper, we present an object-oriented methodology designed to handle multi-annual Satellite Image Time Series (SITS). This method has the objective to automatically analyse a SITS to depict and characterize the dynamic of the areas (the way that the land cover of the areas evolve over time). First, it identifies the spatio-temporal entities (reference objects) to be tracked. Second, the evolution of such entities is described by means of a graph structure and finally it groups together spatio-temporal entities that evolve similarly. The analysis were performed on three study areas to highlight inter (among the study areas) and intra (inside a study area) similarity by following the evolution of the underlying phenomena. The analysis demonstrate the benefits of our methodology. Moreover, we also stress how an expert can exploit the extracted knowledge to pinpoint relevant landscape evolutions in the multi-annual time series and how to make connections among different study areas.  相似文献   

2013年甘肃岷县漳县6.6级地震前热红外异常分析     

蔡丽雯  李戈云 《高原地震》2014,26(4):5-9

应用中国静止气象卫星FY-2E红外遥感资料对2013年甘肃岷县漳县6.6级地震前的热红外异常信息进行研究,结果表明：由地震黑体辐射热异常时空演化图分析知,中强地震前,往往会有较大范围的热异常演变,热异常大面积沿断层分布,震中位置往往位于边界或热异常变化最大处.对比实时的长波辐射涡度场变化,能更好的对应未来地震的发震区域,涡度异常经常分布在震中边界.  相似文献   

Linking pesticides and human health: A geographic information system (GIS) and Landsat remote sensing method to estimate agricultural pesticide exposure     

《Applied geography (Sevenoaks, England)》2015

Accurate pesticide exposure estimation is integral to epidemiologic studies elucidating the role of pesticides in human health. Humans can be exposed to pesticides via residential proximity to agricultural pesticide applications (drift). We present an improved geographic information system (GIS) and remote sensing method, the Landsat method, to estimate agricultural pesticide exposure through matching pesticide applications to crops classified from temporally concurrent Landsat satellite remote sensing images in California. The image classification method utilizes Normalized Difference Vegetation Index (NDVI) values in a combined maximum likelihood classification and per-field (using segments) approach. Pesticide exposure is estimated according to pesticide-treated crop fields intersecting 500 m buffers around geocoded locations (e.g., residences) in a GIS. Study results demonstrate that the Landsat method can improve GIS-based pesticide exposure estimation by matching more pesticide applications to crops (especially temporary crops) classified using temporally concurrent Landsat images compared to the standard method that relies on infrequently updated land use survey (LUS) crop data. The Landsat method can be used in epidemiologic studies to reconstruct past individual-level exposure to specific pesticides according to where individuals are located.  相似文献   

A New Scheme for Predicting Leaf Onset in Summer-Green Vegetation in the Northern Hemisphere          下载免费PDF全文

TIAN Dong-Xiao  ZENG Xiao-Dong 《大气和海洋科学快报》2015,8(5)

A modified thermal time model(MTM) was developed to reproduce the leaf onset for summer-green vegetation in the Northern Hemisphere. The model adopts the basic concept of a thermal time model(TM) in that leaf onset is primarily triggered by growing degree days(GDD). Based on global phenology data derived from satellite observations, a new parameterization for the critical model parameter Tb(i.e., baseline temperature for GDD calculation) has been introduced, and the spatial distribution of Tb was calculated. Simulations of leaf onset during 1982–2000 in the range 30–90°N showed a significant improvement of MTM over the standard TM model with constant Tb. The mean error and mean absolute error of the climatological simulation were 1.11 and 6.8 days, respectively, and 90% of the model error(5th and 95 th percentiles) was between-12.4 and 13.7 days.  相似文献   

北斗卫星通信在应急自动气象站中的应用     

王柏林  花卫东  阳艳红 《气象与环境科学》2015,38(2):115-119

为了能够在发生灾难事故时进行紧急通信,应急自动气象站采用了北斗卫星导航定位系统的简短通信技术。在北斗卫星通信方式设计过程中,采取压缩数据包长度、主动传输+失败应答通信模式、对通信终端采取休眠工作等方式,在保证数据传输质量的同时减少不必要的通信次数,降低系统功耗,延长工作时间。研究结果表明,采用本文的通信设计,可以实现:1)将数据包长度压缩60%,满足了北斗卫星短信包的长度要求。2)兼顾解决了数据完整性问题和通信资费问题,在正常工作状态下采用自动定时传输模式节约通信资费;在通信失败的情况下采用主从应答通信模式,通过向自动气象站发出数据补收命令,及时取得丢失的数据。3)有效地降低了系统的功耗,通信终端平均功耗下降了10%。  相似文献