HABLAN: Multispectral and multiangular remote sensing of artificial light at night from high altitude balloons

Abstract

Some studies have established statistical links between Artificial Light At Night (ALAN) and the risk associated with diseases such as hormone-dependent Cancers (HDC). These links have been identified in part under a yellowish lighting regime and with space-borne images that only detect light travelling upward and that are often blind to the blue or the shorter wavelengths of the visible spectrum. The use of colour images taken by astronauts at the International Space Station (ISS) can detect the blue component of ALAN but it is still restricted to the upward light emissions. It may be expected that the light travelling near horizontal is even more correlated to HDC. Therefore, it is essential to develop multispectral and multiangular remote sensing techniques of ALAN. To achieve this, we suggested a new experiment to observe ALAN from the stratosphere during High Altitude Balloon (HAB) flights. The system use multiple colour cameras to picture a city at different viewing angles and in the three RGB bands (Red, Green and Blue bands). The ultimate goal of the project is to provide better remote sensing data as inputs to numerical radiative transfer models. The model may then be used to infer health risks associated with ALAN. Stratospheric remote sensing makes it possible to measure large areas in a short period of time at low cost compared to space-borne methods. The system High Altitude Balloon Light At Night (HABLAN) was designed to achieve that goal. The first HABLAN experiments were carried out aboard balloon flights of the Canadian Space Agency (CSA) as part of their STRATOS program. In this paper, we present the experimental concept of the HABLAN system and we show some preliminary results.