Arctic ALAN Intensity Change Maps (1992-2013)

This deposit contains Artificial Light at Night (ALAN) maps based on Zhao et al (2022) dataset of CCNL. The maps were used in the publication of “Artificial light at night reveals hotspots and rapid development of industrial activity in the Arctic”.

We implemented an algorithm to filter out all the pixels that were lit only once in the CCNL dataset, that were >5 km away from a pixel that was lit at least twice. We selected the 5-km threshold to retain the areas that were expanding from the previously lit but filter out the outliers. The filtered-out pixels accounted for approximately 3% of the total lit area. We then used the corrected dataset as the basis for our study.

We calculated cumulative ALAN map by summing up the ALAN DN values for every year from 1992 to 2013. We defined values above zero as ‘lit’ while zero values as ‘unlit’.

We calculated pixel-level ALAN intensity trend maps by applying first-order ARIMA to every pixel of ALAN dataset from 1992 to 2013 across the pan-Arctic. We derived the slope of the trendline and tested the significance of the slope (p < 0.05). In the map, areas with significant positive slope in intensity were labeled as “increasing” and areas with significant negative slope as “decreasing”. Lit areas without significant trends were named “lit”.