Weather blog: How air quality has changed during COVID-19 pandemic

Weather Blog: Changing Air Quality
Weather Blog: Changing Air Quality(wrdw)
Published: Nov. 18, 2020 at 6:12 PM EST
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AUGUSTA, Ga. (WRDW/WAGT) - In the world of COVID-19 many things in our lives have changed like how we go to work, go to school, and how much time we spend traveling. With lockdowns and travel restrictions in place, the amount of emissions emitted around the world has been dropping. Using satellites high above our heads NASA is able to track current levels of nitrogen dioxide (N02), the primary pollutant that’s produced by burning fossil fuels. Check out the video from NASA talking about how they tracked pollutant levels across the globe during the pandemic and how models helped show a big difference in what 2020 might have looked like without COVID.

The figure below shows the change in pollutant levels from 2019 to the same time period this year in Wuhan, China, one of the first cities to be impacted by the virus. The top three images show nitrogen dioxide levels from January, 1st - February, 25th, 2019, and the bottom three images show the same dates but in 2020. Notice how the levels in January 2019 are high but drop during the Chinese New Year in early February then spike once the celebrations come to an end. When we compare this to 2020 we see a very different picture, levels are already lower to start off 2020 but continue to stay low going through the Chinese New year and through the end of February.

Sharp contrast between pollution levels in 2019 vs 2020.
Sharp contrast between pollution levels in 2019 vs 2020.(NASA'S Earth Observatory)

NASA estimates that in Wuhan alone pollution levels were down nearly 60% and with the assistance of computer modeling technology, NASA can model what 2020 might have looked like if it was like any other year. To do this they subtract the COVID free 2020 numbers from what was actually observed. It was discovered that Wuhan wasn’t the only location to see a decrease in emissions, cities across Europe and the United States saw a decrease in the pollutant. In Millan, there was a 60% decrease in pollutants and New York City saw a 45% drop once restrictions were put in place. The two images below show a big change in NO2 concentrations on the east coast, mainly in the large metro regions spanning from DC to NYC, but you can also make out a difference here in the two-state.

Overall across the planet, there was a 20% decrease in NO2 concentrations, but as lockdowns and restrictions were slowly lifted pollutant levels started to rise again.

The video above mentioned the GEOS-5 Model or Goddard Earth Observing System version 5 model. It was this model that NASA used to predict where 2020 might have ended up if COVID didn’t happen. GEOS has several different configurations such as the Atmospheric General Circulation Model (AGCM), Ocean General Circulation Model (OGCM), Atmospheric-Ocean General Circulation Model (AOGCM), Chemistry-Climate Model (CCM), and the Chemistry-Transport Model (CTM). Each of these versions of GEOS helps scientists look and model specific aspects of our atmosphere and oceans which provide essential information that tell us what is happening with our planet. Research with these models is still ongoing but if you want to learn more about GEOS and what each of the configurations is used for click here.

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