Suchergebnisse

As a basic agricultural parameter in the formation, transformation, and consumption of surface water resources, soil moisture has a very important influence on the vegetation growth, agricultural production, and healthy operation of regional ecosystems. The Aksu river basin is a typical semi-arid agricultural area which seasonally suffers from water shortage. Due to the lack of knowledge on soil moisture change, the water management and decision-making processes have been a difficult issue for local government. Therefore, soil moisture monitoring by remote sensing became a reasonable way to schedule crop irrigation and evaluate the irrigation efficiency. Compared to in situ measurements, the use of remote sensing for the monitoring of soil water content is convenient and can be repetitively applied over a large area. To verify the applicability of the typical drought index to the rapid acquisition of soil moisture in arid and semi-arid regions, this study simulated, compared, and validated the effectiveness of soil moisture inversion. GF-1 WFV images, Landsat 8 OLI images, and the measured soil moisture data were used to determine the Perpendicular Drought Index (PDI), the Modified Perpendicular Drought Index (MPDI), and the Vegetation Adjusted Perpendicular Drought Index (VAPDI). First, the determination coefficients of the correlation analyses on the PDI, MPDI, VAPDI, and measured soil moisture in the 0–10, 10–20, and 20–30 cm depth layers based on the GF-1 WFV and Landsat 8 OLI images were good. Notably, in the 0–10 cm depth layers, the average determination coefficient was 0.68; all models met the accuracy requirements of soil moisture inversion. Both indicated that the drought indices based on the Near Infrared (NIR)-Red spectral space derived from the optical remote sensing images are more sensitive to soil moisture near the surface layer; however, the accuracy of retrieving the soil moisture in deep layers was slightly lower in the study area. Second, in areas of vegetation coverage, MPDI and VAPDI had a ...

ABSTRACTInternet technologies and e‐commerce have significantly reduced communication and search costs and facilitated trade between distant parties. It has been advocated that the world becomes flat and geographic divisions are gradually irrelevant. However, recent studies have identified a type of location advantage in online platforms, that is, home bias. To further explore the role of geography in online markets, this study investigates another type of location advantage, the country of origin (COO) effect for online sellers. Using a large listing and transaction data set collected from both an e‐commerce retail platform in China and the official Web sites of two foreign brands, we examine the impact of geographic location on online sellers' pricing strategies and transaction quantities. Our research provides empirical evidence supporting the existence of the COO effect for online sellers in the context of foreign branded product exchanges. Furthermore, the results suggest that sellers' location information can be a substitute to their reputation and observable effort in facilitating online transactions.