Recently, five Global LAnd Surface Satellite (GLASS) products have been released: leaf area index (LAI), shortwave broadband albedo, longwave broadband emissivity, incident short radiation, and photosynthetically active radiation (PAR). The first three products cover the years 1982Á2012 (LAI) and 1981Á2010 (albedo and emissivity) at 1Á5 km and 8-day resolutions, and the last two radiation products span the period 2008Á2010 at 5 km and 3-h resolutions. These products have been evaluated and validated, and the preliminary results indicate that they are of higher quality and accuracy than the existing products. In particular, the first three products have much longer time series, and are therefore highly suitable for various environmental studies. This paper outlines the algorithms, product characteristics, preliminary validation results, potential applications and some examples of initial analysis of these products.
Diffuse radiation can increase canopy light use efficiency (LUE). This creates the need to differentiate the effects of direct and diffuse radiation when simulating terrestrial gross primary production (GPP). Here, we present a novel GPP model, the diffuse‐fraction‐based two‐leaf model (DTEC), which includes the leaf response to direct and diffuse radiation, and treats maximum LUE for shaded leaves (ɛmsh defined as a power function of the diffuse fraction (Df)) and sunlit leaves (ɛmsu defined as a constant) separately. An Amazonian rainforest site (KM67) was used to calibrate the model by simulating the linear relationship between monthly canopy LUE and Df. This showed a positive response of forest GPP to atmospheric diffuse radiation, and suggested that diffuse radiation was more limiting than global radiation and water availability for Amazon rainforest GPP on a monthly scale. Further evaluation at 20 independent AmeriFlux sites showed that the DTEC model, when driven by monthly meteorological data and MODIS leaf area index (LAI) products, explained 70% of the variability observed in monthly flux tower GPP. This exceeded the 51% accounted for by the MODIS 17A2 big‐leaf GPP product. The DTEC model's explicit accounting for the impacts of diffuse radiation and soil water stress along with its parameterization for C4 and C3 plants was responsible for this difference. The evaluation of DTEC at Amazon rainforest sites demonstrated its potential to capture the unique seasonality of higher GPP during the diffuse radiation‐dominated wet season. Our results highlight the importance of diffuse radiation in seasonal GPP simulation.
Using remotely sensed satellite products is the most efficient way to monitor global land, water, and forest resource changes, which are believed to be the main factors for understanding global climate change and its impacts. A reliable remotely sensed product should be retrieved quantitatively through models or statistical methods.
This study explored motivation and engagement among North American (the United States and Canada; n = 1,540), U.K. (n = 1,558), Australian (n = 2,283), and Chinese (n = 3,753) secondary school students. Motivation and engagement were assessed via students’ responses to the Motivation and Engagement Scale–High School (MES–HS). Confirmatory factor analysis using Mplus found good fit for each of the four samples. Multi-group invariance tests demonstrated comparable factor structure, reliability, distributional properties, and correlations with a set of validational factors across the four groups. Results hold implications for international assessment of motivation and engagement, research, and data analysis.
Abstract. This study has investigated the relationship among school culture, teachers' job satisfaction, and school effectiveness. It also explored the mediating effect of teachers' job satisfaction on school culture and school effectiveness. Participants of the study include1, 297 teachers from 6 lower secondary and upper secondary schools in Beijing, China. Quantitative methods were used for data generation, consisting of 3 questionnaire-based surveys to measure, separately, school culture, school effectiveness, and job satisfaction from the teachers' perspective. The results indicated positively significant relationships among school culture, teachers' job satisfaction, and school effectiveness and that teachers' job satisfaction partially mediated the impact of school culture on school effectiveness. In light of these results, limitations and directions for future research are provided, as well as implications for education.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.