Lockdown is also changing our Planet at night 🌃

Tutorial: Accessing nightlight observations with satellite data

Sara Aparício
Euro Data Cube
Published in
6 min readMar 25, 2021

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The lockdown restrictions kept people in their homes. Schools were closed, industry stopped and airplanes got grounded. Nightlife has likewise changed. Activities and nightlife spaces were shuttered as they are deemed as non-essential services and potential source for virus transmission. As a consequence, changes in nightlight can be seen from Space. Three Space agencies — ESA, NASA and JAXA have an online tool to explore coronavirus impacts…at night.

eodashboard.org — The COVID-19 Earth observation dashboard developed by the three space agencies offers the possibility to track changes in air, climate change, economic activity and agriculture, through the integration of multiple satellite data provided by NASA, JAXA and ESA.

Exploring nightlight observations with the COVID-19 Earth observation dashboard

The COVID-19 Earth observation dashboard — is accessible at eodashboard.org. Accessing the nightlight data requires online 4 simple steps. On the top left panel, 1) click on ‘Indicators’ to disclose the list of all available indicators and then, 2) select the ‘Nightlights’ indicator. The middle map panel will present the different ‘spotlight’ cities across Europe, Asia and (North) America containing nightlight data. After 3) choosing a city from the middle map, the 4) nightlights map is created and displayed on the right side panel.

…[nightlights indicator] holds the potential to track variations in energy use, migration, and transportation in response to social distancing and lockdown measures.

The comparison of regions before and after guidelines to shelter-in-place began, allows to visualize the extent to which social distancing measures affected various economic activities based on whether light pollution increased or decreased, which highways were shut down, and which cities stayed the same. This indicator holds the potential to track variations in energy use, migration, and transportation in response to social distancing and lockdown measures.

4 Steps to explore nightlight data at eodashboard.org

New York — The city that never sleeps has certainly gone darker.

Taking New York City as a spotlight example. Around March 2020 in hopes of slowing the growing outbreak of the coronavirus, gatherings of more than 500 people were banned. The iconic Broadway initially posed to ‘going dark’ for a month, has ‘gone’ dark for a year now as spectacle industry stopped. Although it is not visible considerable changes in the heart of NYC, the outskirts show a considerably darkening. On the nightlight map below, the darker shades show places with less light while the lighter shades of yellow are areas with more light — allowing to monitor both the magnitude and signature of nighttime phenomena and anthropogenic sources of light emissions.

NYC East: (Right) January vs July 2020 nightlights. Rockville center and Freeport districts: (Middle) January 2020 vs (Right) July 2020.

NYC has begun relaxing pandemic restrictions in recent weeks thanks to the fall in cases and on-going vaccination plan. The reopening of venues will provide “a much needed light at the end of this long, dark tunnel”, as stated by Sade Lythcott, chief executive of the National Black Theatre. This data is also of great interest to depict areas affected by power shortages, as the one that took place in July 2020.

Tokyo — a neon city with dimmer lights?

On the other side of the planet, in the vibrant city of Tokyo, while some areas seemingly remain unchanged, others revealed a decrease in lights at night. Japan’s virus state of emergency is significantly looser than lockdowns elsewhere in the world. It largely calls for more people to work from home and for bars and restaurants to shut from 8 p.m. In December, amid COVID-19 surge, the city has urged restaurants and bars to shut early, and a new state of emergency putting the upcoming Olympics at stake.

Shibuya, Tokyo. Copyright: Image © Alex Maxim

Dimmer lights during December’s state of emergency were most noticeable in the surroundings of the central Tokyo. As example, Shibuya City a major commercial and finance center, housing the two busiest railway stations in the world, shown in some areas decreasing light due to the imposed closing hours. However, overall change in lights are not so obvious in most parts, as bars for instance are too small and difficult to detect using monthly averaged data.

Tokyo (Right) January vs December 2020 nightlights showing dimmer nightlight observations around Shibuya City. (Left): January vs December 2020 nightlights reduction in areas of sports facilities. The area once housed the Yoyogi Olympic Village for the Olympic Games Tokyo 1964.

The ‘Old Continent’ with missing patches.

Also in Europe, cities are showing different looks from Space as a consequence of COVID-19 impacts on night activities. Home to iconic cities, such as Paris (‘the City of Lights’), or Ghent (where the ‘Light Festival’ has just been postponed), restrictions across different sectors led to noticeable change in nightlights observations. At the heart of Europe, Belgium, was specially hit by the pandemic. The country had the world’s highest death rates during the first wave, whereas during the second wave in October 2020 it had the highest infection rate in Europe, leading the country to a second National lockdown from November onwards. The comparison between February 2020, and the two lockdown periods, April and November show areas around Ghent going noticeably darker, as result of closure of non-essential businesses.

(Right): First lockdown in Zelzate, Belgium: February vs April 2020 nightlights. (Left): Second lockdown in Ghent, Belgium: February vs November 2020 nightlights.

However, the comparison between the first and the second lockdown, depicts some differences. Despite less nightlights when compared to pre-pandemic period, the second lockdown shows a less accentuated reduction in nightlights at some locations. In fact, economic impacts of lockdown in Belgium were harder during the first lockdown. This can be mainly explained by the fact that a much greater number of shops were allowed to remain open and in-shop collection services have become much more widely used sales channels. During the second lockdown takeout was possible until 10 p.m. and night shops had to close at 10p.m.).

Meet the Satellite behind nightlight observations

Suomi-NPP Visible Infrared Imaging Radiometer Suite (VIIRS) is the satellite behind the acquisition of nightlight data on eodashboard.

Suomi pioneered the generation of satellite products providing global measurement of nocturnal visible and near-infrared light. The high-resolution nighttime images from space, referred to by NASA as the Black Marble HD dataset, is processed to eliminate light sources like moonlight reflectance and other interferences. Furthermore, before assuming the direct link between decrease of lights and COVID-19-related restrictions it is always important to discard other potential factors for change. Nevertheless, this data can shed a light (pun intended) on how coronavirus-containment strategies have affected local businesses and neighborhoods, deciphering changes in urban business, industry, and transportation activity patterns associated with closures, event cancellations, and reduced vehicle traffic by night.

Quick tip: you can activate night mode on the COVID-19 Earth observation dashboard !

Other tutorials:

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Sara Aparício
Euro Data Cube

Polar & Space science enthusiast. Earth Observation data scientist at @ESA. Wannabe violinist & northern lights chaser.