The response of vegetation cover and dune activity to rainfall,drought and fire observed by multitemporal satellite imagery     

Adrian Fisher  Paul P. Hesse 《地球表面变化过程与地形》2019,44(15):2957-2967

The stable longitudinal dunes in the northern Simpson Desert, Australia, were observed in satellite imagery to become more active after vegetation cover was reduced by fire and drought. Subsequent rainfall events also resulted in significant vegetation regrowth and dune stabilization. These switches between more active and stable conditions have not been previously described in the largely vegetated dune fields of central Australia. The observations, made on 12 dune sites, relied on high spatial resolution satellite imagery to observe dune crest activity, and seasonal Landsat fractional cover imagery to observe vegetation cover changes. The non-photosynthetic vegetation (NPV) component of the fractional vegetation cover images revealed significant changes in hummock grass cover on the dunes between 1988 and 2018, with a positive relationship with the three-year cumulative rainfall, disrupted by two periods of patchy burning. Only those sites that had burnt became active, and only after vegetation cover had remained low (NPV < 16%) during the ‘Millennium Drought’. There is no threshold in vegetation cover, below which dune crests become active, but active dune features require four-years of low NPV cover (< 16%) to develop. The large rainfall event that ended the drought increased NPV cover, stabilizing the dunes. Similar hummock grass covered dunes are present across large areas of the arid zone, and are likely to respond in similar ways, given that fire and drought are common occurrences in Australia. © 2019 John Wiley & Sons, Ltd. © 2019 John Wiley & Sons, Ltd.  相似文献   

Optical and radar remote sensing data for forest cover mapping in Peninsular Malaysia     

Nazarin Ezzaty Mohd Najib  Kasturi Devi Kanniah 《Singapore journal of tropical geography》2019,40(2):272-290

This study aims to map forest cover in Peninsular Malaysia using satellite images as deforestation is of concern in the recent decades, and is an important environmental issue for the future too. The Carnegie Landsat Analysis System‐Lite (CLASlite) program was used in this study to detect forest cover in Peninsular Malaysia using Landsat satellite data. The results of the study show that CLASlite algorithm misclassified some oil palm, rubber and urban areas as forest vegetation. A reliable forest cover map was produced by first combining Landsat and ALOS PALSAR images to identify oil palm, rubber and urban areas, and then subsequently removing them. The HH and HV polarization data of ALOS PALSAR (threshold method) could detect oil palm plantations with 85.26 per cent of overall accuracy. For urban area detection, Enhance Build up Index (EBBI) using spectral bands from Landsat provided higher overall accuracy of 94 per cent. These methods produced a forest cover reading of 5 914 421 ha with an overall classification accuracy of 94.5 per cent. The forest cover (including rubber areas) detected in this study is 0.38 per cent higher than the percentage of 2010 forest cover detected by the Forestry Department of Peninsular Malaysia. The technique described in this paper presents an alternative and viable approach for updating forest cover maps in Malaysia.  相似文献   

河北省地震局邯郸中心台远程监控系统     

张小涛  吴鹏  闫俊岗  张磊  贾华 《地震地磁观测与研究》2018,39(4):213-217

根据河北省地震局邯郸中心台监控需求，提出一种基于STM8的台站远程监控系统，对控制单元、电源模块、视频监控模块、仪器远程控制模块等进行说明，介绍软件设计与人机交互界面。在邯郸中心台远程监控中实际应用，认为此系统可提高台站维护效率，保障观测数据的连续可靠具有较高的应用价值。  相似文献   

Towards automated 10–30 m resolution land cover mapping in insular South-East Asia     

Jukka Miettinen  Chenghua Shi  Soo Chin Liew 《国际地球制图》2019,34(4):443-457

In this study, we create and critically analyse an automated decision tree classification approach for regional level land cover mapping in insular South-East Asian conditions, using a combination of 10–30 m resolution optical and radar data. The resulting map contains 11 land cover classes and reveals a great deal of contextual information due to high spatial resolution. A limited accuracy assessment indicates 59–97% class wise accuracies. The unprecedented spatial detail of closed canopy oil palm mapping (with user’s accuracy of 90%) is seen as the most promising feature of the mapping approach. The incapability of separating primary forests from other tree cover, and the large variety of different landscapes (e.g. home gardens and tea plantations) classified as shrubland, are considered the main areas for future improvement. Overall, the study demonstrates the great potential of multi-source 10–30 m resolution high data volume land cover mapping approaches in insular South-East Asian conditions.  相似文献   

Evaluation of ICA and CEM algorithms with Landsat-8/ASTER data for geological mapping in inaccessible regions     

Amin Beiranvand Pour  Yongcheol Park  Tae-Yoon S. Park  Jong Kuk Hong  Mazlan Hashim  Jusun Woo 《国际地球制图》2019,34(7):785-816

Many regions remain poorly studied in terms of geological mapping and mineral exploration in inaccessible regions especially in the Arctic and Antarctica due to harsh conditions and logistic difficulties. Application of specialized image processing techniques is capable of revealing the hidden linear mixing spectra in multispectral and hyperspectral satellite images. In this study, the applications of Independent component analysis (ICA) and Constrained Energy Minimization (CEM) algorithms were evaluated for Landsat-8 and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) remote sensing data for geological mapping in Morozumi Range and Helliwell Hills areas, Northern Victoria Land (NVL), Antarctica. The results of this investigation demonstrate the capability of the two algorithms in distinguishing pixel and subpixel targets in the multispectral satellite data. The application of the methods for identifying poorly exposed geologic materials and subpixel exposures of alteration minerals has invaluable implications for geological mapping and mineral exploration in inaccessible regions.  相似文献   

Evaluating ice‐rafted debris as a proxy for glacier calving in Upernavik Isfjord,NW Greenland     

Flor Vermassen  David J. Wangner  Laurence M. Dyke  Sabine Schmidt  Amalie E. Cordua  Kurt H. Kjr  Konstanze Haubner  Camilla S. Andresen 《第四纪科学杂志》2019,34(3):258-267

Records of ice‐rafted debris (IRD) in sediments are commonly used as a proxy for iceberg production and to reconstruct past changes of glacier stability. However, the interpretation of IRD is complex as multiple processes modulate its variability. This study investigates the relationship between IRD variability and glaciological change by measuring IRD records from Upernavik Fjord and comparing these to frontal positions of Upernavik Isstrøm during the past century. Results show that the spatial variability of IRD deposition throughout the fjord is high, indicating that randomness inherent to IRD distorts the calving signal. However, we investigate whether IRD records can be combined to improve the reconstruction, as previously suggested, and show the importance of core site selection and number of cores on this approach. The outer‐fjord core compares relatively well to the observed front positions and this is reflected in the composite record: increased IRD deposition in 1937–1946, 1968–1980, and 1996–1999 occurred during periods of faster retreat. Comparison with climatic records shows that the calving episodes in the late ‘30 s/early ‘40 s and late ‘90 s are related to warm ocean and air temperatures, whereas intensified retreat and calving during the ‘70 s reflects partly an internal glacier response to the fjord geometry.  相似文献   

Data Cube on Demand (DCoD): Generating an earth observation Data Cube anywhere in the world     

《International Journal of Applied Earth Observation and Geoinformation》2020

To tackle Big Data challenges such as Volume, Variety, and Velocity, the Earth Observations Data Cube (EODC) concept has emerged as a solution for lowering barriers and offering new possibilities to harness the information power of satellite EO data. However, installing, configuring, and managing an EODC instance is still difficult requiring specific knowledge and capabilities. Consequently, facilitating and automating the generation and provision of EODC given specific user’s requirements can be beneficial.In response to this issue, this paper presents the Data Cube on Demand (DCoD) approach, a proof-of-concept that aims at facilitating the generation and use of an EODC instance virtually anywhere in the World. Users are only required to specify an area of interest; select the types of sensors between Landsat 5-7-8 and Sentinel-2; choose a desired temporal frame; and provide their email address to receive notifications. Then automatically an empty ODC instance is instantiated and desired data are ingested.The proposed approach has been successfully tested in two sites in Bolivia and DRC in the field of environmental monitoring. It has lowered many complexity barriers of such a new technology; greatly facilitated the generation and use of the Data Cube technology; enhanced data sovereignty; and ultimately can help reaching large adoption and acceptance.  相似文献   

天宝TX8三维激光扫描仪在卧式金属罐容积计量中的应用     

谷田平 《测绘通报》2019,(5):152-154

基于加油站对卧式金属罐容积内部交接的应用需要，本文采用天宝TX8三维激光扫描仪进行容积测量标定，并与传统的容积比较法及激光点阵法对某加油站20 m³卧式金属罐进行数据比较及建模分析。测试数据表明，天宝TX8在卧式金属罐容积标定方面较激光点阵法符合性更高，建模更加全面、直观、高效，为其在其他测量领域及力学建模方面的拓展应用提供了可能。  相似文献   

基于实测光谱模拟Landsat-8 OLI数据估算非光合 植被覆盖度     

王光镇  王静璞  韩柳  柴国奇  王周龙 《地球信息科学学报》2018,20(11):1667-1678

定量的估算非光合植被覆盖度（Fractional Cover of Non-photosynthetic Vegetation, f_NPV）对草原生态系统碳储存、植被生产力、土壤侵蚀和火灾监测均具有重要的意义。本文以锡林郭勒草原实测高光谱和样方盖度为数据源,利用NPV（Non-Photosynthetic Vegetation）、PV（Photosynthetic Vegetation）、BS（Bare Soil）的平均光谱通过线性光谱混合模型模拟得到混合场景光谱,寻找区分NPV/PV/BS的敏感性波段,然后分别评价不同多光谱指数与f_NPV的相关性。最后利用野外混合场景实验验证光谱指数估算f_NPV的有效性。在此基础上,探讨基于OLI数据的NDVI（Normalized Difference Vegetation Index）-DFI（Dead Fuel Index）特征空间是否满足三元线性混合模型的基本假设。结果表明：短波红外（SWIR）波段是区分NPV/PV/BS的敏感性波段,以此为基础构建的OLI-DFI指数具备有效区分NPV/PV/BS的潜力。在模拟混合场景条件下,OLI-DFI和MODIS-DFI指数均与f_NPV呈显著相关,决定性系数R²分别为0.84和0.94,均方根误差RMSE分别为0.09和0.05,而NDI和NDSVI指数与f_NPV相关性很低。与模拟混合场景相比,在野外混合场景下OLI-DFI和MODIS-DFI指数估算f_NPV的有效性均有一定程度的降低,R²分别为0.65和0.75,RMSE分别为0.14和0.12。基于OLI数据构建的NDVI-DFI特征空间满足三元线性混合模型的基本假设,可有效的估算f_NPV。  相似文献   

Evaluating metrics derived from Landsat 8 OLI imagery to map crop cover     

Rei Sonobe  Yuki Yamaya  Hiroshi Tani  Xiufeng Wang  Nobuyuki Kobayashi  Kan-ichiro Mochizuki 《国际地球制图》2019,34(8):839-855

Developing techniques are required to generate agricultural land cover maps to monitor agricultural fields. Landsat 8 Operational Land Imager (OLI) offers reflectance data over the visible to shortwave-infrared range. OLI offers several advantages, such as adequate spatial and spectral resolution, and 16 day repeat coverage, furthermore, spectral indices derived from Landsat 8 OLI possess great potential for evaluating the status of vegetation. Additionally, classification algorithms are essential for generating accurate maps. Recently, multi-Grained Cascade Forest, which is also called deep forest, was proposed, and it was shown to give highly competitive performance for classification. However, the ability of this algorithm to generate crop maps with satellite data had not yet been evaluated. In this study, the reflectance at 7 bands and 57 spectral indices calculated from Landsat 8 OLI data were evaluated for its potential for crop type identification.  相似文献