最新刊期
卷 25 ， 期 9 ， 2021
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摘要：Quantitative remote sensing in China began in the 1980s and has achieved unprecedentedly rapid development in the past decade. Around 2012, China surpassed the United States for the first time and became the country with the most articles of remote sensing published in English in the world. Especially in recent years, the number of articles has been about twice that of the United States. Although China has been at the forefront of the world in the research on inversion methodology and is a large country in quantitative remote sensing, it is not sufficiently powerful on the whole to be in the leading position in the world in most sub-fields. After reviewing the development history of quantitative remote sensing in the world and China, this paper briefly discusses some problems and challenges of quantitative remote sensing in China from eight aspects: data acquisition and pre-processing, forward radiative transfer modeling, inversion, high-level product production, ground observation, cloud platform construction, education and application, Some expectations and preliminary suggestions are also put forward.关键词：quantitative remote sensing;inversion;high-level products;ground observation networks;remote sensing clouds- 2894
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发布时间：2021-09-30
Scholar's View Point
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摘要：High-spatiotemporal-resolution global multi-class land cover data play a critical role in the studies of biogeochemical cycles of the Earth system and global climate change. Among the existing open products, higher-resolution global multi-class land cover data are available for a single or short period of time, while annual ones have limited class, preventing longer-term analysis of land cover change in fine spatial detail. Therefore, long time, high spatial resolution and high temporal frequency global land cover are needed.In this paper, with the support of the Google Earth Engine platform, we proposed a method composed of data fusion, change detection and machine learning based on existing global land cover maps in 2015, Landsat imagery and samples after manual interpretation to develop annual global land cover data (Annual Global Land Cover-2000-2015) from 2000 to 2015 at 30 m resolution. Based on AGLC-2000-2015 data, we selectively analyzed dynamic change of land cover in three typical regions (the Pearl River Delta of China, Selin Co lake of Tibetan Plateau and the Amazon rainforest of Brazil).Our results show relatively high accuracy of AGLC-2000-2015. Mean overall accuracy and Kappa coefficient of global land cover product for the year 2015 (AGLC-2015) are 76.10% and 0.72, respectively. The accuracies are considerably higher than that of existing global land covet products at 30m resolution, such as Globeland30 (OA=63.49%, Kappa=0.58), FROM-GLC (OA=61.41%, Kappa=0.55), and GLC-FCS30 (OA=63.46%, Kappa=0.57). The overall accuracy and Kappa coefficient of the Random Forest classification model are 84.10% and 0.81, respectively. In addition, the mean overall accuracy of Random Forest classification model at continental scale is more than 80.00%, showing that this model has good performance on global multi-class land cover mapping.We analyzed the land cover changes for the 2000—2015 period in three selected regions. Urban area has increased substantially by an average of 195.96 km2 in the Pearl River Delta of China, with 85% of the newly developed impervious surface encroaching on cropland. Selin Co lake responses significantly to the warming climate with expanding at a rate of 17.95 km2, and the expansion is most pronounced in the north bank. Forest in the south part of Amazon has decreased by a total area of 46356.53 km2, most of which is converted to cropland, showing forest destruction for cropland.AGLC-2000-2015 can effectively reflect the distribution and annual change of global land cover classes at 30 m resolution from 2000 to 2015, providing fundamental data for research and application related to land surface processes.关键词：remote sensing;global land cover;30 m resolution;Landsat imagery;annual land cover change- 3949
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发布时间：2021-09-30
Data Articles
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摘要：China High-resolution Earth Observation System (CHEOS) was first proposed in 2006. The main goal of CHEOS is building a new Earth observation system with high spatial, temporal, and spectral resolution, achieving all-weather, all-day, and global coverage observation capability, thereby providing operational applications for satisfying the requirements of national economic and social development. As the first satellite mission in China specifically for air quality monitoring, GF-5 satellite was launched on May 9, 2018. GF-5 is configured with six payloads, including a VIS and SWIR (shortwave infrared) hyperspectral camera, spectral imager, greenhouse gas detector, atmospheric environment infrared detector at very high spectral resolution, differential absorption spectrometer for atmospheric trace gas, and a multiangle polarization detector.The Directional Polarimetric Camera (DPC) is the first Chinese multiangle polarized earth observation satellite sensor. DPC aims to obtain multiangle polarization radiation data of the Earth’s atmosphere, which can provide information on the temporal and spatial distribution of global aerosols and clouds to satisfy the requirements of global climate change research, atmospheric environment monitoring, and high-accuracy atmospheric correction of remote sensing data. The Environmental trace gas Monitoring Instrument (EMI) payload onboard GF-5 is the first Chinese satellite-borne spectrometer with the aim to measure atmospheric pollutants from space. The Chinese EMI instrument is expected to contribute to the understanding of global air quality and atmospheric chemistry, similar to predecessor European and American satellite missions, e.g., the Ozone Monitoring Instrument (OMI) and TROPOspheric monitoring instrument (TROPOMI). Several trace gases (e.g., NO2, O3, SO2, BrO, and HCHO) and aerosol can be measured by EMI. The greenhouse Gas Monitoring Instrument (GMI) is a short-wavelength infrared (SWIR) hyperspectral-resolution spectrometer onboard the Chinese satellite GF-5 that uses a Spatial Heterodyne Spectroscopy (SHS) interferometer to acquire interferograms. The GMI was designed to measure and study the source and sink processes of carbon dioxide and methane in the troposphere, where the greenhouse effect occurs. AIUS is the first occultation spectrometer developed in China; it aims to detect the trace gases over the Antarctic. AIUS operates in a solar synchronous orbit, with a nominal height of 705 km. The instrument is a Fourier transform infrared spectrometer, and its main objective is to measure O3 and other species in the stratosphere and upper troposphere to study the ozone temporal variations over the Antarctic.关键词：remote sensing;GF-5;DPC (Directional Polarization Camera);EMI (Environment Monitoring Instrument);GMI (Greenhouse-gases Monitoring Instrument);AIUS (Atmospheric Infrared Ultraspectral Senor)- 1844
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发布时间：2021-09-30 -
摘要：To obtain the temperature, pressure and trace gas profiles by infrared occultation sounding needs accurate pointing information. For the first-level spectral data of Atmospheric Infrared Ultraspectral Sounder aboard on satellite GF-5 (GF-5 AIUS), the spectral changes at different tangent heights at the full effective bands are analyzed in this paper. Then, a method for tangent height correction using look-up tables is used based on empirical statistics. Look-up tables are established using forward radiative transfer model, namely, Atmospheric Radiative Transfer Simulator (ARTS) with the atmospheric background profiles built using MLS and ACE-FTS Level 2 products for the last five years. The atmospheric transmittance background profiles represent the atmospheric state from 0 km to 120 km in the vertical direction with a grid width of 1 km. In the lower tangent height section (10—20 km), the N2 absorption band (2490—2520 cm-1) is selected to simulate the transmittance spectrum, and the low-level tangent height in the Level 1 data is corrected by a look-up table correction method. In the higher tangent height section (20—90 km), the transmittance spectrum is also simulated, and the O3 absorption band (1020—1150 cm-1) is used for correction. The correction algorithm adopts the method of global minimum root mean square error for statistical experiments and determines the minimum correction radius of 15 km. Finally, the inversion bands of the three atmospheric components of O3, HCl, and N2O are selected, and corrected transmittance data are compared with simulated transmittance, and verification of inversion product accuracy are performed. Results show that on the inversion channels of O3, HCl, and N2O, the corrected observed transmittance and simulated transmittance data are in good agreement, and the maximum observation deviation is less than 0.1, which shows that the tangent height correction algorithm can obtain a good effect. Meanwhile, based on Aura MLS and ACE-FTS Level 2 product, the cross-validation of O3, HCl, and N2O single profile is performed. The results show that the single profile value of O3 product is less than that of MLS product and higher than that of ACE-FTS product, with absolute deviation of less than 1 ppmv and relative deviation of less than 50% below 20 km and less than 20% above 20 km. The single profile value of HCl retrieved by GF5-AIUS is less than that of MLS and ACE-FTS products, with absolute deviation of less than 0.5 ppbv and relative deviation of less than 50% below 50 km. The single N2O profile value retrieved by GF5-AIUS is less than the ACE-FTS Level 2 product and higher than the MLS Level 2 below 25 km and above 40 km. In addition, the result is opposite in the range of 25—40 km; the absolute deviation between GF5-AIUS and ACE-FTS Level 2 products is less than 10 ppbv in the range of 30—60 km, and the relative deviation is approximately 200%. The absolute deviation is less than 25 ppbv, but the relative deviation is less than 25% below 30 km. Above 30 km, the content of N2O decreases, and the inversion error increases. Therefore, using N2 absorption channel and O3 absorption channel to establish look-up tables for GF-5 AIUS Level 1 data correction can satisfy the requirements of inversion. The disadvantage of this method is that the atmospheric background database requires regular updating to ensure a more accurate atmospheric transmittance look-up table.关键词：infrared occultation detection;GF-5 AIUS;tangent height correction;N2 absorption channels;O3 absorption channels- 791
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发布时间：2021-09-30
Atmospheric Remote Sensing
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摘要：The ground processing system of the high-resolution satellites is an important component of the high-resolution earth observation system. Following the principles of standardization, safety and reliability, maintainability, economy, and advanced technology, a remote sensing data comprehensive processing platform, which can realize the functions of data ingestion, multilevel standard data production, archiving, simulation, evaluation, distribution services, radiometric and geometric calibration, observation management of the payloads on GF-1 to GF-7 satellites, is designed and developed.The ground processing system adopts the cloud computing ground processing architecture based on the HADOOP platform and integrates the internal storage of nodes into a massive data storage system through the HDFS distributed file system. It also realizes the united scheduling and large-scale parallel processing of massive data through the Yarn resource management system. Moreover, it studies and develops the high-precision processing algorithms of the multispectral, hyper-spectral, infrared, microwave, Lidar, and atmosphere detection payloads on the satellites.The high-resolution satellite ground processing system builds a multisatellite comprehensive processing platform for massive satellite data. The capabilities of the ground processing system have been substantially improved in data integrated processing, data storage and management, and data distribution services; it provides standard data products to users with high accuracy and quality.It has 400 trillion calculations per second and highly automated data processing capacity of more than 20 TB per day. It can process a wide range of satellite payload types for GF-1 to GF-7 satellites. In the normal mode, the data processing time of each orbit is not more than 2 hours, and the emergency processing time is not more than 45 minutes.The system has 25 PB scalable storage and management capabilities of massive remote sensing image data. The products are stored online and near line within the life cycle, and level 0 data are permanently archived.For data distribution, the system can distribute more than four million scene data every year and supports 1000 external users to visit and retrieve the data on the service website at the same time. The average retrieval response time is less than 10 seconds. It also supports 200 external users to download data products online.The system has the continuous operation ability of 7×24 hours. The operation stability is better than 99%. The main and backup switches of the key business equipment are completed within 10 minutes after the failure. The mean time to repair is 4 hours.The high-resolution satellite ground processing system has realized satellite data ingestion, standard product processing, archiving, simulation, evaluation, distribution, calibration, payload management, and data sharing services. It has also realized the comprehensive data processing of a wide range of remote sensing data, which cover optical, submeter high spatial resolution, multimode radar, geosynchronous orbit, hyperspectral resolution, atmospheric, stereo mapping, and Lidar earth observation. A multisatellite and multiload remote sensing data product system have been established to provide multisource remote sensing data for land, ocean, agriculture, disaster reduction, forestry, water conservancy, environment, earthquake, meteorology, transportation, surveying, and mapping users. It has played an important role in promoting China’s economic construction, social development, scientific and technological progress, and serving China’s belt and road initiatives.关键词：cloud computing;high-resolution satellite;ground processing system;remote sensing data processing- 1009
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发布时间：2021-09-30 -
摘要：The Bidirectional Reflectance Distribution Function (BRDF) is not only a key geophysical parameter for land surface remote sensing, but also an important parameter for radiation correction of the spaceborne optical remote sensing instruments. Observation equipment used for traditional field object multiangle measurement is generally relatively complex and heavy, and the transportation and assembly processes are cumbersome. Observing targets is easy restricted by terrain and traffic, and efficient and rapid field measurements are difficult to perform. In recent years, UAVs can be used as new observation platforms in current remote sensing experiments due to their advantages, such as simple operation of equipment, flexible transportation, and observation methods.A ground surface BRDF measurement device, observation scheme, and data processing flow based on a UAV platform are innovatively designed. Using a combination of a multirotor low-altitude drone and a gimbal, equipped with a portable ground object spectrometer and a follow-up camera, can provide high-precision positioning and angle control for multiangle observation of ground targets, thereby achieving multiazimuth and sky for fixed targets. This design scheme and observation process are adopted to carry out multiple multiangle spectral observation experiments of stable and uniform desert targets in the Dunhuang radiation correction field, and the experimental observation data are used to estimate the site BRDF model parameters based on the Ross-Li nuclear driving model, and MODIS. Land surface BRDF product (MCD43C1) and reflectivity product (MOD/MYD09) are compared and verified.Field experiments have verified the reliability of this new equipment. At the same time, the analysis results of observation data show that the BRDF parameters of Dunhuang surface measured by the proposed device have good consistency with MODIS remote sensing products, and the relative deviation of each band is within 5%.This study shows that the BRDF observation system based on multirotor drones provides a new and flexible observation method for the reflection characteristics of ground objects in the direction of the target. It can greatly reduce the investment of manpower and material resources while ensuring the accuracy of observation, which is worthy of widespread promotion and application.关键词：UAV;desert;bidirectional reflectance distribution function;directional reflectance;calibration field- 1277
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发布时间：2021-09-30 -
摘要：Aiming at the problems of limited research, application of extracting rural roads with high-resolution remote sensing data, and insufficient accuracy of extraction results, a new improved full convolution rural road extraction network model Distributed Convolution network (DC net) is proposed; it combines void convolution and Air Spatial Pyramid Pooling (ASPP) structure. The model extracts the depth feature information of the road based on the full convolution encoding and decoding structures. At the same time, in accordance with the characteristics of the slender rural roads, the ASPP structure based on the hollow convolution is added between the decoded layers to extract the multiscale characteristic information of the road, and the Field of View (FOV) is expanded without sacrificing the spatial resolution of the feature, thereby improving the recognition rate of narrow and fine rural roads. Some suburban areas of Changzhutan city group are considered the experimental objects and the domestic satellite remote sensing image of Gaogaoer as the experimental data. Experimental results are compared with those of the classical methods of all convolution networks. The results show that: (1) the proposed road extraction model DC net is feasible in rural road extraction, with the overall extraction average accuracy reaching 98.72%, indicating high extraction accuracy; (2) comparative results of the effect of several classic full convolution network models on rural road extraction, DC net extraction accuracy and connectivity, as well as tree and shadow shading in the aspect of block are acceptable; (3) the improved road extraction model of the entire proposed convolution network can effectively extract the feature information of rural roads in high-resolution remote sensing images. The overall extraction effect is improved; it provides a new approach for improving the precision of rural road extraction based on domestic high-resolution images.Based on the full convolution network model in deep learning, this paper proposes an improved full convolution rural road extraction model DC net which combines hole convolution and ASPP structure. According to the characteristics of long and thin and connectivity of rural roads, this method combined with hole convolution to expand the receptive field of feature map in the process of model training, which makes the extraction of rural roads more complete.关键词：Full Convolution Network;Dilated Convolution Network;Atrous convolution;ASPP;Rural road extraction- 1311
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发布时间：2021-09-30
Technologies and Methodologies
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摘要：In order to study the temporal and spatial evolution of inner lakes in Dongting Lake area, this paper uses remote sensing interpretation, data statistical analysis and historical comparison methods based on 10 periods of historical topographic maps and aerospace remote sensing data since 1930s. It analyze the spatial distribution and temporal change of inner lakes in Dongting Lake area since the middle of the Republic of China. The accuracy test is carried out by using the current land using database in 2018, with the accuracy reaching 98.62%. The results show that the number and area of inner lakes in Dongting Lake area have increased from 640 and 994.30 km2 in 1938 to 1057 and 1578.33km2 in 2018. The change process did not show a continuous increasing trend, but experienced an increase, decrease, and increase. The three phases of time series change show undulating characteristics. From the middle period of the Republic of China(1930) to the early days of the founding of the People’s Republic of China(1958), the number and area of the inner lakes showed a rapid increase trend due to the massive reclamation of rivers and lakes. After that, from 1959 to 1978, inner lakes were reclaimed in large numbers because of the agricultural policy of “take grain as the key link”, number and area of inner lakes shrunk to the their lowest values since the middle period of the Republic of China (1930). Since the reform of the People’s Republic of China(1979), with the adjustment of agricultural structure, aquaculture and “returning farmland to lake”, the area of inner lakes has shown a significant increase. The inner lakes in the Dongting Lake area show an overall increasing trend, but the changes in inner lakes with different scales, types, and different characteristics in different regions are different. Diveded by scale, the areas of forbidden inner lakes (area ≥1 km2) and non-forbidden inner lakes (<1 km2) showed an overall trend of simultaneous increase and decrease, but the area changes of forbidden inner lakes have significant phases; divded by type, the area of the residual inner lakes is obviously larger than that of the reservoir-like inner lakes and the dumb inner lakes, and its area accounts for more than 70% of the total area of the inner lake; divided by region, the change in the area of the inner lake in the original polder area is divided into two stages: a decrease period and an increase period, the area of the inner lake in the new polder area is on the rise as a whole, and it has experienced a process from scratch.In general, reclamation of the lake is the main driving force for the formation of inner lakes. Food security and aquaculture are the main reasons for the change of inner lakes. The deposition and over cultivation of inner lakes e pose a serious threat to the ecological environment of inner lakes. The research results can provide objective data for the ecological restoration and environmental protection of Dongting Lake area.关键词：since the Republic of China;historical map;Remote Sensing Technique;the Dongting Lake area;inner lakes;temporal and spatial evolution- 1295
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发布时间：2021-09-30 -
摘要：Plant height and Above-Ground Biomass (AGB) are important agronomic parameters for crop growth monitoring. Therefore, efficiently and timely acquire this information of potato plant is important for guiding farmland production management. Traditionally, manual actual surveys are time-consuming, laborious and destructive, and fail to meet the modern needs of smart agriculture. With the advancement of science and technology, remote sensing technology has attracted people’s attention for its advantages of non-destructive, high-throughput, and rapid acquisition of phenotype information of ground objects. Compared with satellite, aerial and ground remote sensing, UAV remote sensing technology is widely popularized in precision agriculture monitoring due to its strong mobility, simple operation, low operating cost, and the ability to obtain high-resolution digital orthophotos under the cloud. In this study, the UAV equipped with high-definition digital camera was used to obtain the image data of potato with budding periods, tuber formation period, tuber growth period, starch accumulation period and maturity period, and the height (H) and AGB of potato plant on the ground were measured, and the longitude, dimension and height of Ground Control Points (GCPs) were obtained by Global Positioning System (GPS) from March to July 2019. Firstly, the Digital Surface Model (DSM) was generated by structure from motion algorithm based on the image data of the experimental area and the location information of GCPs, and the Hdsm (potato plant height) of each growth period was extracted based on DSM. Then, combining 26 image indices with better performance in AGB monitoring based on the digital number value of the image, crop height of field survey by ruler (H) and crop height extracted based on DSM difference calculation (Hdsm) into a new data set. The first 7 indices and Hdsm based analyzing the correlation between these parameters (26 vegetation indices, H and Hdsm) and AGB were screened to construct the AGB estimation model of five growth periods. Finally, in order to further increase the variance of the different model, Multiple Linear Regression (MLR), Support Vector Machine (SVM) and Artificial Neural Network (ANN) are selected to build the AGB estimation model based on the sensitivity parameters. Through the quantitative analysis of the model, the optimal estimation model is selected for each growth period to monitor crop conditions. The results showed that: the extracted plant height (Hdsm) is fitted with the measured plant height (R2=0.86, RMSE=6.36cm, NRMSE=13.42%); the AGB estimation model was constructed by three different modeling methods in each growth period, in which the model by integrating with Hdsm into vegetation indices was better; it is found that the effect of MLR model (R2 =0.61, 0.74, 0.77, 0.72 and 0.60) with incorporating the Hdsm into image indices in each growth period to estimate AGB is better than that of SVM (R2=0.60, 0.69, 0.73, 0.69 and 0.58) and ANN (R2=0.56, 0.67, 0.71, 0.65 and 0.55). The results of this research help solve the problem of monitoring AGB in the traditional way and provide reference for real-time monitoring of potato growth and yield prediction accurately.关键词：unmanned aerial vehicle;digital image;digital surface model;potato;plant height;above-ground biomass- 1063
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发布时间：2021-09-30
Remote Sensing Applications
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摘要：High-scoring remote sensing has the advantages of “high availability”, “easy process”, “high spatial resolution”, “multiple satellites”, “rich information acquisition” and “strong long-term observation ability”, etc., which are useful for realizing forest fires. The prevention and control objectives of “playing early, playing small, and fighting” provide important technical means.In this paper, the high-scoring remote sensing technology is used in the emergency rescue of the “4·20” forest fire disaster in Mianning, Sichuan, and the forest fire elements are quickly extracted through the high-scoring remote sensing texture features to obtain information about the location of the water source near the fire site, rescue forces, and fire-fighting routes; use it The spectral characteristics sense the abnormal brightness temperature in the area to detect fire points, monitor the evolution of the fire situation and the development of the fire; carry out dynamic monitoring of the range of the fire area and migration changes based on the spectral characteristics, predict the development trend of the fire, and propose emergency rescue deployment suggestions in real time. Support disaster relief; use the Normalized Vegetation Index (NDVI) to complete the extraction of fire areas, fire intensity information and preliminary disaster assessment.In view of the secondary hidden dangers after the fire, combined with the distribution of fire areas and topographical factors, 28 potential debris flow gullies were delineated after the fire, and it was proposed based on the proportion of the high intensity area in the debris flow gully, the length of the main gully, the vertical drop of the gully bed, the drainage area and the gully. Influencing factors such as the average slope of the internal fire zone are used to evaluate the susceptibility of potential debris flow gully. Four of them are predicted to be highly prone, 11 are medium prone, and 13 are low prone.The research results show that high-scoring remote sensing technology can predict forest fire emergency rescue and post-fire secondary hidden hazards, effectively support forest fire disaster emergency treatment, and the method has good timeliness and generalizability. It is an emergency decision-making for forest fire fighting. Disaster prevention and mitigation activities such as effective deployment of fighting forces, scientific decision-making, prediction of secondary hazards after fire, and post-disaster reconstruction provide important decision support basis for disaster prevention and mitigation activities.关键词：high-scoring remote sensing technology;mianning fire;emergency fire fighting;debris flow after the fire;pre-judgment of hidden dangers- 1176
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发布时间：2021-09-30
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