These are maps of artificial night sky radiance that were produced by the Light Pollution Science and Technology Institute (ISTIL), and described in the paper "The New World Atlas of Artificial Night Sky Brightness" (Falchi et al. 2016).The data are stored in a 2.9 Gb geotiff file, on a 30 arcsecond grid. The map reports simulated zenith radiance data in [mcd/m^2]. The map is based on data from the VIIRS Day Night Band (DNB, MIller et al. 2013), which has been propagated through the atmosphere using the radiative transfer code reported in (Cinzano and Falchi, 2012). The upward emission function and the radiance calibration were obtained using data from Sky Quality Meters (including data from Duriscoe et al. 2007; Falchi 2010; Kyba et al 2013, 2015 and Zamorano et al. 2016).Note that the maps report artificial light only! The zenith radiance from natural sources such as stars and the Milky Way are not included, and must be added in order to match the data that would be obtained from an actual outdoor measurement.A kmz file for quick view of the data is also provided. Access to the FTP site to download the data can be requested via the data request form on the landing page.Version History:13 November 2019: change of the licence to CC BY NC 4.0 (after end of embargo period).
Traditionally, it is necessary to pre-process remote sensing data to obtain top of canopy (TOC) reflectances before applying physically-based model inversion techniques to estimate forest variables. Corrections for atmospheric, adjacency, topography, and surface directional effects are applied sequentially and independently, accumulating errors into the TOC reflectance data, which are then further used in the inversion process. This paper presents a proof of concept for demonstrating the direct use of measured top-ofatmosphere (TOA) radiance data to estimate forest biophysical and biochemical variables, by using a coupled canopy-atmosphere radiative transfer model. Advantages of this approach are that no atmospheric correction is needed and that atmospheric, adjacency, topography, and surface directional effects can be directly and more accurately included in the forward modelling. In the case study, we applied both TOC and TOA approaches to three Norway spruce stands in Eastern Czech Republic. We used the SLC soil-leaf-canopy model and the MODTRAN4 atmosphere model. For the TOA approach, the physical coupling between canopy and atmosphere was performed using a generic method based on the 4-stream radiative transfer theory which enables full use of the directional reflectance components provided by SLC. The method uses three runs of the atmosphere model for Lambertian surfaces, and thus avoids running the atmosphere model for each new simulation. We used local sensitivity analysis and singular value decomposition to determine which variables could be estimated, namely: canopy cover, fraction of bark, needle chlorophyll, and dry matter content. TOC and TOA approaches resulted in different sets of estimates, but had comparable performance. The TOC approach, however, was at its best potential because of the flatness and homogeneity of the area. On the contrary, the capacities of the TOA approach would be better exploited in heterogeneous rugged areas. We conclude that, having similar performance, the TOA approach should be preferred in situations where minimizing the pre-processing is important, such as in data assimilation and multi-sensor studies.
The project aims at investigating the fundamentals of heat and mass transfer phenomena in high-temperature multiphase reactive flows exposed to high-flux irradiation. The application is focused on the development of solar reactor technology for the production of hydrogen via steam-gasification of carbonaceous materials using concentrated solar radiation. Solar hybrid thermochemical processes, as the one targeted in this project, make use of fossil fuels as the chemical source of hydrogen production and concentrated solar energy as the energy source of high-temperature process heat. Industrially relevant examples include the thermal gasification of coal, the thermal cracking of natural gas, the thermal reforming of natural gas, and the carbothermic reduction of metal oxides, for producing synthetic fluid fuels with upgraded calorific value. These hybrid solar processes offer viable and efficient routes for fossil fuel decarbonization and CO2 avoidance, and further create a transition path towards solar hydrogen. This project contributes to the advancement of the thermo-sciences aimed at the development of solar chemical technologies that will lead to cleaner, more efficient, and sustainable energy utilization.