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61.
62.
Marcel Dobber Robert Voors Ruud Dirksen Quintus Kleipool Pieternel Levelt 《Solar physics》2008,249(2):281-291
We have constructed a new high resolution solar reference spectrum in the spectral range between 250 and 550 nm. The primary
use of this spectrum is for the calibration of the Dutch – Finnish Ozone Monitoring Instrument (OMI), but other applications
are mentioned. The incentive for deriving a new high resolution solar reference spectrum is that available spectra do not
meet our requirements on radiometric accuracy or spectral resolution. In this paper we explain the steps involved in constructing
the new spectrum, based on available low and high resolution spectra and discuss the main sources of uncertainty. We compare
the result with solar measurements obtained with the OMI as well as with other UV-VIS space-borne spectrometers with a similar
spectral resolution. We obtain excellent agreement with the OMI measurements, which indicates that both the newly derived
solar reference spectrum and our characterization of the OMI instrument are well understood. We also find good agreement with
previously published low resolution spectra. The absolute intensity scale, wavelength calibration and representation of the
strength of the Fraunhofer lines have been investigated and optimized to obtain the resulting high resolution solar reference
spectrum. 相似文献
63.
In the recent decade, the construction projects related to shallow geothermal energy engineering have undergone rapid development in Shandong Province. The predominant type of these developments and applications was heat exchange through buried tubes and the main targets were residential and office buildings. However, an overwhelming majority of the completed geothermal heat pump projects lacked monitoring devices so that they were unable to comprehensively reflect the background values for the geothermal fields within the province and few researches were conducted on their influence on the geological environment. In this paper, locations for monitoring shallow geothermal energy and their validity of the monitoring point deployment were studied in view of the development and application status as well as geological background conditions of various projects located in multiple cities providing data support for analyzing the fluctuation trend and influence of large-scale shallow geothermal energy applications on the shallow geothermal and the feasibility and parameter designs of newly built systems in Shandong Province in the future. 相似文献
64.
The use of time series satellite data allows for the temporally dense, systematic, transparent, and synoptic capture of land dynamics over time. Subsequent to the opening of the Landsat archive, several time series approaches for characterizing landscape change have been developed, often representing a particular analytical time window. The information richness and widespread utility of these time series data have created a need to maintain the currency of time series information via the addition of new data, as it becomes available. When an existing time series is temporally extended, it is critical that previously generated change information remains consistent, thereby not altering reported change statistics or science outcomes based on that change information. In this research, we investigate the impacts and implications of adding additional years to an existing 29-year annual Landsat time series for forest change. To do so, we undertook a spatially explicit comparison of the 29 overlapping years of a time series representing 1984–2012, with a time series representing 1984–2016. Surface reflectance values, and presence, year, and type of change were compared. We found that the addition of years to extend the time series had minimal effect on the annual surface reflectance composites, with slight band-specific differences (r ≥ 0.1) in the final years of the original time series being updated. The area of stand replacing disturbances and determination of change year are virtually unchanged for the overlapping period between the two time-series products. Over the overlapping temporal period (1984–2012), the total area of change differs by 0.53%, equating to an annual difference in change area of 0.019%. Overall, the spatial and temporal agreement of the changes detected by both time series was 96%. Further, our findings suggest that the entire pre-existing historic time series does not need to be re-processed during the update process. Critically, given the time series change detection and update approach followed here, science outcomes or reports representing one temporal epoch can be considered stable and will not be altered when a time series is updated with newly available data. 相似文献
65.
本文简要介绍了吉林省地震台网布局,监测手段设置及仪器装备状况,重点对测震台网,地震前兆台网的监控能力进行分析,给出了台网和实际控制范围,对目前台网存在的问题以及今后的发展情况进行了讨论。 相似文献
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WU Ai-min HAO Ai-bing GUO Hai-peng LIU Jing-tao ZHANG Er-yong WANG Huang WANG Xin-feng WEN Xue-ru ZHANG Cui-guang 《地下水科学与工程》2020,8(3):195-209
This paper reviewed the main achievements of hydrogeological survey in China, summarized the significant progress of hydrogeological survey over the past decade, and forecasted the key responsibilities for hydrogeological survey in the p14th Five-year Planq. The significant progress includes: China established the 1: 50 000 standard hydrogeological survey system with Chinese characteristics and produced the new generation of high-quality hydrogeological maps; the national groundwater monitoring project was completed and accepted, which marks China taking the leading position in groundwater monitoring internationally; fruitful results were achieved in the national groundwater quality survey, and groundwater quality background values were basically identified and checked; hydrogeological and environmental geological survey was continuously promoted in karst areas and the ecological restoration of rocky desertification achieved remarkable results; China strengthened layer exploration techniques for groundwater, integrating the key and practical techniques of layer exploration and monitoring; the exploration of groundwater in the poverty-stricken regions and old revolutionary base areas were effectively promoted to strongly guarantee the poverty alleviation and drinking water safety; the mystery of desert groundwater was uncovered, making up for the shortage of 1: 250 000 hydrogeological survey in the Badain Jaran Desert; and more efforts were made to conduct survey on the water resources in the basin, and to finish the unified measurement of national-scale groundwater level. 相似文献
69.
Surface arrays became an important tool for monitoring the induced seismicity in hydraulic fracturing experiments and for assessing the impact of fluid injection on the fracturing process of microearthquakes. The layout of sensors plays a key role in this task because it controls the accuracy of event locations and retrieved seismic moment tensors. We simulate various configurations of grid sensor arrays characterized by a different number of sensors, array span, sensor spacing, depth of sources and various shear/tensile source mechanisms of events. The moment tensor inversion is carried out using synthetically calculated P-wave amplitudes with added random noise. A bias in the solutions is evaluated by errors in the double-couple percentage of inverted moment tensors because the double-couple errors inform us about the sensitivity of the network to detect the shear/tensile fracturing mode of induced microearthquakes. The results show that the accuracy of the double-couple percentage is mostly controlled by the offset-to-depth ratio R defined as the ratio of half of the network size to the event depth. The optimum value of R is in the range of 0.75–1.5 irrespective of the type of the focal mechanism. If 121 (11 × 11) sensors are distributed in a regular grid and recorded data are characterized by a 10% random noise, the double-couple error is less than 6%. This error increases, if R is not optimum or if the number of sensors is reduced. However, even sparse arrays with 49 (7 × 7) or 16 (4 × 4) sensors can yield a reasonable accuracy, provided the surface grid arrays are designed to have an optimum size. 相似文献
70.
Timo Lähivaara Alireza Malehmir Antti Pasanen Leo Kärkkäinen Janne M.J. Huttunen Jan S. Hesthaven 《Geophysical Prospecting》2019,67(8):2115-2126
Convolutional neural networks can provide a potential framework to characterize groundwater storage from seismic data. Estimation of key components, such as the amount of groundwater stored in an aquifer and delineate water table level, from active-source seismic data are performed in this study. The data to train, validate and test the neural networks are obtained by solving wave propagation in a coupled poroviscoelastic–elastic media. A discontinuous Galerkin method is applied to model wave propagation, whereas a deep convolutional neural network is used for the parameter estimation problem. In the numerical experiment, the primary unknowns estimated are the amount of stored groundwater and water table level, while the remaining parameters, assumed to be of less of interest, are marginalized in the convolutional neural network-based solution. Results, obtained through synthetic data, illustrate the potential of deep learning methods to extract additional aquifer information from seismic data, which otherwise would be impossible based on a set of reflection seismic sections or velocity tomograms. 相似文献