Light Pollution Range Delta

Risksv05.00 credits/per_km2

Responsible:Niccolò Calandri

Light Pollution Range Delta

Overview

The Light Pollution Range Delta compares the mean nighttime brightness between two consecutive time periods. The annual mean represents the average nighttime radiance over the period. By computing the difference between the means of two distinct periods, we obtain a measure of how artificial lighting patterns have changed over time.

Formula:

Delta = Mean_LP(period 2) - Mean_LP(period 1)
Mean_LP(period) = mean(LP, period)

Positive delta: seasonal lighting variability has increased — potentially indicating growing seasonal tourism activity (summer resort lighting), new seasonal light installations (events, markets), or intensified commercial/industrial activities with more pronounced seasonal patterns.
Negative delta: lighting variability has decreased, suggesting illumination stabilization — possibly associated with light pollution regulations, replacement with constant-output lighting systems, or reduced seasonal activity.
Near-zero delta: seasonal lighting patterns have remained stable between the two periods.

Light pollution has significant impacts on nocturnal biodiversity, interfering with reproductive cycles of night pollinators, migratory bird navigation, and circadian rhythms of numerous species. Monitoring seasonal variability is particularly relevant for understanding how light pressures vary throughout the year and how these patterns are changing over time.

Calculation Methodology

Data acquisition: monthly VIIRS DNB (Day/Night Band) composites for both reference periods.
Pre-processing: filters applied to remove moonlight, aurora, and fire effects.
Mean calculation for period 1: mean radiance computed pixel-wise across all valid composites of the first period.
Range calculation for period 2: same for year N+1.
Delta calculation: pixel-wise subtraction: Delta = Mean(period 2) - Mean(period 1).
Validation: pixels lacking valid data in either period masked as NoData.

Data Sources

Source Code	Name	Provider	Resolution	Availability
WRD_VRDNB_99	VIIRS Day/Night Band	NOAA/NASA	~500m (resampled to 30m)	From 2012

Technical Notes

VIIRS DNB native resolution is ~500m; data is resampled to 30m for compatibility but effective resolution remains the original.
Monthly composites already filter many noise sources, but sporadic events (fires, reflective snow) can influence extreme values.
Very remote areas with little artificial lighting may show delta dominated by sensor noise.

References

Elvidge, C.D., et al. (2017). "VIIRS night-time lights." International Journal of Remote Sensing, 38(21), 5860-5879.
Falchi, F., et al. (2016). "The new world atlas of artificial night sky brightness." Science Advances, 2(6), e1600377.

Data Sources & References

Sources

WRD_VRDNB_99

Methodology

Il delta del range dell'inquinamento luminoso viene calcolato confrontando i range annuali di radianza notturna tra due periodi consecutivi. Per ciascun periodo si calcola la media della radianza. Il delta è ottenuto tramite sottrazione pixel per pixel: Delta = Media(periodo 2) - Media(periodo 1). I dati provengono da VIIRS DNB (Day/Night Band) con risoluzione nativa ~500m, ricampionata a 30m.