Abstract: The increase in artificial light at night (ALAN) is a global concern, while the pattern of ALAN pollution inside urban areas has not yet been fully explored. To fill this gap, we developed a novel method to map fine-scale ALAN pollution patterns in urban bird habitats using high spatial resolution ALAN satellite data. First, an ALAN pollution map was derived from JL1-3B satellite images. Then, the core habitat nodes (CHNs) representing the main habitats for urban birds to inhabit were identified from the land cover map, which was produced using Gaofen2 (GF2) data, and the high probability corridors (HPCs), indicating high connectivity paths, were derived from Circuitscape software. Finally, the ALAN patterns in the CHNs and HPCs were analysed, and the mismatch index was proposed to evaluate the trade-off between human activity ALAN demands and ALAN supply for the protection of urban birds. The results demonstrated that 115 woodland patches covering 4149.0ha were selected as CHNs, and most of the CHNs were large urban parks or scenic spots located in the urban fringe. The 2923 modelled HPCs occupying 1179.2ha were small remaining vegetation patches and vegetated corridors along the major transport arteries. The differences in the ALAN pollution patterns between CHNs and HPCs were mainly determined by the characteristics of the green space patches and the light source types. The polluted regions in the CHNs were clustered in a few regions that suffered from concentrated and intensive ALAN, while most of the CHNs remained unaffected. In contrast, the 727 HPCs were mainly polluted by street lighting was scattered and widely distributed, resulting a more varying influence to birds than that in the CHNs. Relating patterns of the ALAN to bird habitats and connectivity provides meaningful information for comprehensive planning to alleviate the disruptive effects of ALAN pollution.

Abstract: The radiative transfer equation (RTE) is a common approach to solving the transfer of electromagnetic energy in heterogeneous disperse media, such as atmospheric environment. One-dimensional RTE is a linear boundary value problem that is well suited to plane-parallel atmosphere with no diffuse intensity entering the top of the atmosphere. In nighttime regime, the ground-based light sources illuminate the atmosphere at its bottom interface. However, the light-pollution models conventionally use radiant intensity function rather than radiance. This might potentially result in a number of misconceptions. We focused on similarities and fundamental differences between both functions and clarified distinct consequences for the modeling of skyglow from finite-sized and semi-infinite light-emitting flat surfaces. Minimum requirements to be fulfilled by a City Emission Function (CEF) are formulated to ensure a successful solution of standard and inverse problems. It has been shown that the horizon radiance of a flat surface emitting in accordance with Garstang's function (GEF) would exceed any limit, meaning that the GEF is not an appropriate tool to model skyglow from distant sources. We developed two alternative CEFs to remedy this problem through correction of direct upward emissions; the most important strengths of the modified CEFs are detailed in this paper. Numerical experiments on sky luminance under well-posed and ill-posed boundary conditions were made for two extreme uplight fractions (F) and for three discrete distances from the city edge. The errors induced by replacing radiance with radiant intensity function in the RTE are generally low (15%–30%) if F is as large as 0.15, but alteration of the luminance may range over 1–3 orders of magnitude if F approaches zero. In the latter case, the error margin can increase by a factor of 10–100 or even 1000, even if the angular structure of luminance patterns suffers only weak changes. This is why such a shift in luminance magnitudes can be mistakenly interpreted as the effect of inaccurate estimate of lumens per head of the population rather than the effect of cosine distortion due to ill-posed inputs to the RTE. For that reason, a thorough revision (and/or remediation) of theoretical and computational models is suggested.

Abstract: This research discusses the feasibility of replacing or supporting artificial lighting with Transgenic Bioluminescent Plants (TBP), as a means of minimizing light pollution, reducing electrical energy consumption and de-carbonizing urban and suburban outdoor environments, creating sustainable conditions and enriching the quality of life. Until now, no information is given about the light output of any TBPs and the question “Are the TBPs capable of producing the necessary lighting levels for exterior lighting?” is unanswered. For this reason, a new methodology is proposed for selecting and analyzing the lighting output potential of transgenic plants ted for specific climatic conditions. This methodology considers growth and reduction factors, as well as a formulae for estimating the plants’ luminous output by performing light measurements. Results show that transgenic plants in medium growth can emit a median luminous flux of up to 57 lm, a value that can definitely support low lighting requirements when used in large numbers of plants. From the lighting measurements and calculations performed in this research, the light output of the TBPs for a typical road with 5m width was found equal to 2lx. The amount of plants required was 40 at each side of the road for every 30m of streets with P6 road class. The results show that the use of bioluminescent plants can actually contribute to the reduction of energy consumption, concerning only the lighting criterium, thus creating an enormous opportunity for a new state-of- the-art market and research that could potentially minimize CO2 emissions and light pollution, improve urban and suburban microclimate, mitigate the effects of climate change, as well as provide an alternative means of lighting affecting both outdoor lighting design and landscape planning in suburban and urban settings. Moreover, further research should be applied considering also other possible ecological impacts before applying TBPs for exterior lighting applications.