Accurate monitoring of soil moisture is crucial in hydrological and ecological studies. Cosmic-ray neutron sensors (CRNS) measure area-average soil moisture at field scale, filling a spatial scale gap between in-situ observations and remote sensing measurements. However, its applicability has not been assessed in the agricultural-pastoral ecotone, a data scarce semi-arid and arid region in Northwest China (APENC). In this study, we calibrated and assessed the CRNS (the standard N0 method) estimates of soil moisture. Results show that Pearson correlation coefficient, RP, and the root mean square error (RMSE) between the CRNS soil moisture and the gravimetric soil moisture are 0.904 and less than 0.016 m3 m−3, respectively, indicating that the CRNS is able to estimate the area-average soil moisture well at our study site. Compared with the in-situ sensor network measurements (ECH2O sensors), the CRNS is more sensitive to the changes in moisture in its footprint, which overestimates and underestimates the soil moisture under precipitation and dry conditions, respectively. The three shape parameters a0, a1, a2 in the standard calibration equation (N0 method) are not well suited to the study area. The calibrated parameters improved the accuracy of the CRNS soil moisture estimates. Due to the lack of low gravimetric soil moisture data, performance of the calibrated N0 function is still poor in the extremely dry conditions. Moreover, aboveground biomass including vegetation biomass, canopy interception and widely developed biological soil crusts adds to the uncertainty of the CRNS soil moisture estimates. Such biomass impacts need to be taken into consideration to further improve the accuracy of soil moisture estimation by the CRNS in the data scarce areas such as agricultural-pastoral ecotone in Northwest China.
ABSTRACTInternational communication and global cooperation have greatly accelerated the worldwide spread of dengue fever, increasing the impact of imported cases on dengue outbreaks in non-naturally endemic areas. Existing studies mostly focus on describing the quantitative relationship between imported cases and local transmission but ignore the space-time diffusion mode of imported cases under the influence of individual mobility. In this paper, we propose a comprehensive framework at a fine scale to establish the disease transmission network and a mathematical model, which constructs ‘source-sink’ links between the imported and indigenous cases on a regular grid with a spatial resolution of 1 km to explore the diffusion pattern and spatiotemporal heterogeneity of imported cases. An application to Guangzhou, China, reveals the main flow and transmission path of imported cases under the influence of human movement and identifies the spatiotemporal distribution of transmission speed according to the time lag of each source-sink link. In addition, we demonstrate that using individual-based movement data and socio-economic factors to study human mobility and imported cases can help to understand the driving forces of dengue spread. Our research provides a comprehensive framework for the analysis of early dengue transmission patterns with benefits to similar urban applications. 相似文献
Under the theoretical framework of the New Trade Theory and the New Economic Geography, Home Market Effects (HMEs) is considered
to be important sources of comparative advantage and significant reasons for industry agglomeration. Through the analysis
on the input-output tables in China, the paper confirms the existence of HMEs for the manufacturing industries and their export
trades on the national and provincial level in China. Several conclusions have been drawn in this study. Firstly, there exist
prominent HMEs for manufacturing industries related with nondurable goods and materials in China. Secondly, 10 of the 15 kinds
of manufacturing industries considered in this study display the existence of HMEs. Thirdly, the comparative advantage of
factor endowment for the export trade of manufacturing industries is declining, while HMEs for them are increasing. Fourthly,
among the 30 provincial regions studied in this paper, 11 regions show the existence of HMEs, most of which are located in
the eastern coast region. This paper illustrates the simultaneous existence of the comparative advantage of factor endowment
and scale economies of HMEs for China’s manufacturing industries. HMEs will not only be the new dynamic for the increase of
manufacturing industries and their export trade, but also be the primary power for urban economic growth, industry improvement,
and urban space expansion for China. 相似文献
This paper develops a wide-band multi-spectral space for color representation with Aitken PCA al-gorithm. This novel mathematical space using the broad-band spectra matching metod aims at improving the accuracy of color representation as well as reducing costs for processing and storing multi-spectral images.The results show that the space can present our experimental original spectral spaces(i,e.Munsell color matt and DIN-6164 color chips)with high efficiency,and that the spanning space with three eigenvectors can present the original space at more than 98% CSCR,and when 5eigenvectors are used it can cover almost the whole original spaces. 相似文献