Air Quality

NASA, ESA (European Space Agency) and JAXA (Japan Aerospace Exploration Agency) have created a dashboard of satellite data showing impacts on the environment and socioeconomic activity caused by the global response to the coronavirus (COVID-19) pandemic. The dashboard will be released on Thursday, June 25 during a tri-agency media briefing. The briefing speakers are: • Josef Aschbacher, director of ESA Earth Observation Programmes • Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate • Koji Terada, vice president and director general for the Space Technology Directorate at JAXA • Shin-ichi Sobue, project manager for JAXA’s ALOS-2 mission • Ken Jucks, program scientist for NASA’s OCO-2 and Aura missions • Anca Anghelea, open data scientist, ESA Earth observation programmes

Over the past several weeks, the United States has seen significant reductions in air pollution over its major metropolitan areas. Similar reductions in air pollution have been observed in other regions of the world. These recent improvements in air quality have come at a high cost, as communities grapple with widespread lockdowns and shelter-in-place orders as a result of the spread of COVID-19. One air pollutant, nitrogen dioxide (NO2), is primarily emitted from burning fossil fuels (diesel, gasoline, coal), coming out of our tailpipes when driving cars and smokestacks when generating electricity. Therefore, changes in NO2 levels can be used as an indicator of changes in human activity. However, care must be taken when processing and interpreting satellite NO2 data as the quantity observed by the satellite is not exactly the same as the NO2 abundance at ground level. NO2 levels are influenced by dynamical and chemical processes in the atmosphere. For instance, atmospheric NO2 levels can vary day-to-day due to changes in the weather, which influences both the lifetime of NO2 molecules as well as the dispersal of the molecules by the wind. It is also important to note that satellites that observe NO2 cannot see through clouds, so all data shown is for days with low amounts of cloudiness. If processed and interpreted carefully, NO2 levels observed from space serve as an effective proxy for NO2 levels at Earth's surface. NASA's air quality group is also monitoring other air pollutants, such as sulfur dioxide (SO2). Major anthropogenic activities that emit SO2 include electricity generation, oil and gas extraction, and metal smelting. SO2 is emitted during electricity generation if the coal burned has sulfur impurities that are not removed (or not “scrubbed”) from the plant’s exhaust stacks. For more information on what pollutants NASA satellites observe, visit the NASA Air Quality website.

Animated Gif of tropospheric NO2, March 25 -April 25 of Indian subcontinent.

On March 24, 2020, Prime Minister Modi ordered a nationwide stay-at-home order for India’s 1.3 billion citizens in an attempt to slow the spread of COVID-19.

Animated Gif -tropospheric NO2 from March 25-April 25 time series in southwestern US.

On June 1, the World Health Organization noted that Central and South American countries have become “the intense zones” for COVID-19 transmission. The Ozone Monitoring Instrument (OMI) on board NASA’s Aura satellite provides data that indicate that restrictions on human activity have led to about a 36% decrease in NO₂ levels in Rio de Janeiro, Brazil, relative to previous years. Other large cities in South America show similar decreases in NO₂: 36% in Santiago, Chile; 35% in São Paolo, Brazil; and 40% in Buenos Aires, Argentina. One notable exception is in Lima, Peru, showing a 69% decrease. The large decrease may partly be associated with natural variations in weather that can, for instance, disperse air pollution more quickly. Additional analysis is required to determine the amount of the decrease of NO₂ in Lima that is associated with a decrease in human activity. A notable increase in NO₂ occurred in northern South America, which is likely associated with increased agricultural burning in 2020 relative to previous years.

These images show the impact the spread of the novel coronavirus (COVID-19) has had on reducing air pollution in the United States as widespread lockdowns and shelter-in-place orders have been put in place. The images show a reduction in the levels of nitrogen dioxide (NO2)—a noxious gas emitted by motor vehicles, power plants, and industrial facilities—as measured by the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite in March 2020. The “without stay-at-home orders” images show average monthly NO2 concentrations during March and April from 2015 through 2019, while the “during stay-at-home orders” images show average monthly concentrations in March and April 2020. These improvements in air quality have come at a high cost, as communities grapple with the impacts of COVID-19. The data indicate that the NO2 levels in March and April 2020 are much lower on average across the United States when compared to the mean of 2015 to 2019.

Preventative measures adopted to reduce the rate of spread of COVID-19 in the U.S. prompted an overall slowdown in economic activity and fewer vehicles on the roadways in the spring of 2020. To examine changes in air quality in California, NASA constructed weekly averaged nitrogen dioxide (NO2) maps for March and April 2020 at 0.05° grid spacing from high-quality, cloud-free retrievals provided by Tropospheric Monitoring Instrument (TROPOMI) level 2 data. During first weekday period (March 2-6, pre-shutdown) when COVID-19 measures were yet to be implemented, the largest tropospheric NO2 concentrations were observed in Los Angeles and bordering counties with a less prominent peak in NO2 around San Francisco. The TROPOMI scans also resolved areas of enhanced NO2 along the heavily trafficked corridor of State Route 99 (SR-99) in the Central Valley. As initial, soft COVID-19 measures were adopted by businesses in California during the second weekday period, March 9-13, TROPOMI observed strong reductions in tropospheric column NO2 around the large cities of Los Angeles and San Francisco along with noticeable decreases along SR-99. When California announced statewide “shelter-in-place” orders during the third weekday period, March 16-20, further decreases in NO2 were apparent throughout all populated areas in the state and along SR-99. Further weekly areages showed variable decreases in NO2 as decreased economic activity continued. Overall, these observed reductions in TROPOMI NO2 throughout the spring season are the result of decreased emissions on top of the seasonal changes in meteorological conditions.

Animated Gif -tropospheric NO2 from March 15-April 15 time series in southeastern US.

Animated Gif -tropospheric NO2 from March 15-April 15 time series in the state of Florida

On June 1, the World Health Organization noted that Central and South American countries have become “the intense zones” for COVID-19 transmission. The Ozone Monitoring Instrument (OMI) on board NASA’s Aura satellite provides data that indicate that restrictions on human activity have led to about a 36% decrease in NO₂ levels in Rio de Janeiro, Brazil, relative to previous years. Other large cities in South America show similar decreases in NO₂: 36% in Santiago, Chile; 35% in São Paolo, Brazil; and 40% in Buenos Aires, Argentina. One notable exception is in Lima, Peru, showing a 69% decrease. The large decrease may partly be associated with natural variations in weather that can, for instance, disperse air pollution more quickly. Additional analysis is required to determine the amount of the decrease of NO₂ in Lima that is associated with a decrease in human activity. A notable increase in NO₂ occurred in northern South America, which is likely associated with increased agricultural burning in 2020 relative to previous years.

On June 1, the World Health Organization noted that Central and South American countries have become “the intense zones” for COVID-19 transmission. The Ozone Monitoring Instrument (OMI) on board NASA’s Aura satellite provides data that indicate that restrictions on human activity have led to about a 36% decrease in NO₂ levels in Rio de Janeiro, Brazil, relative to previous years. Other large cities in South America show similar decreases in NO₂: 36% in Santiago, Chile; 35% in São Paolo, Brazil; and 40% in Buenos Aires, Argentina. One notable exception is in Lima, Peru, showing a 69% decrease. The large decrease may partly be associated with natural variations in weather that can, for instance, disperse air pollution more quickly. Additional analysis is required to determine the amount of the decrease of NO₂ in Lima that is associated with a decrease in human activity. A notable increase in NO₂ occurred in northern South America, which is likely associated with increased agricultural burning in 2020 relative to previous years.

On June 1, the World Health Organization noted that Central and South American countries have become “the intense zones” for COVID-19 transmission. The Ozone Monitoring Instrument (OMI) on board NASA’s Aura satellite provides data that indicate that restrictions on human activity have led to about a 36% decrease in NO₂ levels in Rio de Janeiro, Brazil, relative to previous years. Other large cities in South America show similar decreases in NO₂: 36% in Santiago, Chile; 35% in São Paolo, Brazil; and 40% in Buenos Aires, Argentina. One notable exception is in Lima, Peru, showing a 69% decrease. The large decrease may partly be associated with natural variations in weather that can, for instance, disperse air pollution more quickly. Additional analysis is required to determine the amount of the decrease of NO₂ in Lima that is associated with a decrease in human activity. A notable increase in NO₂ occurred in northern South America, which is likely associated with increased agricultural burning in 2020 relative to previous years.

On June 1, the World Health Organization noted that Central and South American countries have become “the intense zones” for COVID-19 transmission. The Ozone Monitoring Instrument (OMI) on board NASA’s Aura satellite provides data that indicate that restrictions on human activity have led to about a 36% decrease in NO₂ levels in Rio de Janeiro, Brazil, relative to previous years. Other large cities in South America show similar decreases in NO₂: 36% in Santiago, Chile; 35% in São Paolo, Brazil; and 40% in Buenos Aires, Argentina. One notable exception is in Lima, Peru, showing a 69% decrease. The large decrease may partly be associated with natural variations in weather that can, for instance, disperse air pollution more quickly. Additional analysis is required to determine the amount of the decrease of NO₂ in Lima that is associated with a decrease in human activity. A notable increase in NO₂ occurred in northern South America, which is likely associated with increased agricultural burning in 2020 relative to previous years.

Using computer models to generate a COVID-free 2020 for comparison, NASA researchers found that since February, pandemic restrictions have reduced global nitrogen dioxide concentrations by nearly 20%. The model simulation and machine learning analysis took place at the NASA Center for Climate Simulation. Its “business as usual” scenario showed an alternate reality version of 2020—one that did not experience any unexpected changes in human behavior brought on by the pandemic. From there it is simple subtraction. The difference between the model simulated values and the measured ground observations represents the change in emissions due to the pandemic response. The researchers received data from 46 countries—a total of 5,756 observation sites on the ground—relaying hourly atmospheric composition measurements in near-real time. On a city-level, 50 of the 61 analyzed cities show nitrogen dioxide reductions between 20-50%. Wuhan, China was the first municipality reporting an outbreak of COVID-19. It was also the first to show reduced nitrogen dioxide emissions—60% lower than simulated values expected. A 60% decrease in Milan and a 45% decrease in New York followed shortly, as their local restrictions went into effect. This visualization presents the deviation from the model as colored hemispheres at each observation site. Whether a site is under lockdown is denoted by a smaller dot at each site, colored grey to denote "no lockdown," and green to denote "under lockdown." Additionally, the deviation for each of three cities, Wuhan, Madrid, and New York is presented as a scrolling line graph at the top of the visualization.

Methane is a powerful greenhouse gas that traps heat 28 times more effectively than carbon dioxide over a 100-year timescale. Concentrations of methane have increased by more than 150% since industrial activities and intensive agriculture began. After carbon dioxide, methane is responsible for about 20% of climate change in the twentieth century. Methane is produced under conditions where little to no oxygen is available. About 30% of methane emissions are produced by wetlands, including ponds, lakes and rivers. Another 20% is produced by agriculture, due to a combination of livestock, waste management and rice cultivation. Activities related to oil, gas, and coal extraction release an additional 30%. The remainder of methane emissions come from minor sources such as wildfire, biomass burning, permafrost, termites, dams, and the ocean. Scientists around the world are working to better understand the budget of methane with the ultimate goals of reducing greenhouse gas emissions and improving prediction of environmental change. For additional information, see the Global Methane Budget. The NASA SVS visualization presented here shows the complex patterns of methane emissions produced around the globe and throughout the year from the different sources described above. The visualization was created using output from the Global Modeling and Assimilation Office, GMAO, GEOS modeling system, developed and maintained by scientists at NASA. Wetland emissions were estimated by the LPJ-wsl dynamic global vegetation model, which simulates the temperature and moisture dependent methane emission processes using a variety of satellite data to determine what parts of the globe are covered by wetlands. Other methane emission sources come from inventories of human activity. The height of Earth’s atmosphere and topography have been vertically exaggerated and appear approximately 50-times higher than normal in order to show the complexity of the atmospheric flow while the bathymetry below sea level is exaggerated by 11.6-times. Outflow from different regions result from different sources. For example, high methane concentrations over South America are driven by wetland emissions while over Asia, emissions reflect a mix of agricultural and industrial activities. Emissions are transported through the atmosphere as weather systems move and mix methane around the globe. In the atmosphere, methane is eventually removed by reactive gases that convert it to carbon dioxide. Understanding the three-dimensional distribution of methane is important for NASA scientists planning observations that sample the atmosphere in very different ways. Satellites like GeoCarb, a planned geostationary mission to observe both carbon dioxide and methane, look down from space and will estimate the total number of methane molecules in a column of air. Aircraft, like those launched during NASA’s Arctic Boreal Vulnerability Experiment (ABOVE) sample the atmosphere along very specific flight lines, providing additional details about the processes controlling methane emissions at high latitudes. Atmospheric models help place these different types of measurements in context so that scientists can refine estimates of sources and sinks, understand the processes controlling them and reduce uncertainty in future projections of carbon-climate feedbacks.

Air pollution can appear as a gray or orange haze enveloping a city. What the naked eye can’t see are the hundreds of chemical reactions taking place to produce that pollution. NASA science can reveal a more complete picture of atmospheric chemistry. A NASA visualization shows 96 chemical species that help form one common air pollutant — surface ozone. While ozone in the stratosphere is critical to maintaining life on earth, surface ozone is a toxic gas to most plant and animal species. This visualization uses the GEOS Composition Forecasting (GEOS-CF) computer model, which incorporates 240 chemical species and how they interact with each other and the weather through over 700 chemical reactions. All of these chemical reactions directly or indirectly impact the formation of ozone. Capturing such complexity requires satellites, the GEOS-CF model, and a supercomputer all working in concert. As the visualization progresses, it cycles through chemicals loosely grouped into seven ‘families’ based on their physical and chemical properties: • Ox • Extended HOx family • Hydrocarbons • Isoprene oxidation • Aerosols • Halogens • Extended NOx family More information on each family can be found on the visualization webpage. The dynamic behavior of some of these chemical species can indicate certain events in the atmosphere. The model covers the time period from July 22, 2018 to October 2, 2018, which includes several notable atmospheric events. Both the Carr Fire and the Mendocino Complex Fire, occurring in late July 2018, released a large amount of hydrocarbons and extended HOx, which can be seen in the model. The latter-occurring Hurricane Florence is also visible, as indicated by the impacted halogens in this atmospheric model. Satellites observe chemical species in the atmosphere, both those emitted from natural and human sources and those formed from other pollutants. Yet, even several hundred thousand observations a day leave data gaps. Merging satellite data with NASA’s GEOS-CF model yields not only a snapshot of chemistry throughout the atmosphere at any given time but also the ability to predict air quality worldwide. This model makes a 5-day forecast daily using the NASA Center for Climate Simulation’s Discover supercomputer. Developed jointly with several government and non-profit partners, these forecasts offer a new tool for academic researchers, government scientists, air quality managers, and the general public. Potential applications include flight campaign planning, support of satellite observations, and mitigation of air pollution.

This visualization shows the global distribution of aerosols, generated by NASA’s GEOS-FP data assimilation system, from August 1, 2019 to January 14,2020—capturing the aerosols released by the extreme bushfires in Australia in December 2019 and January 2020 and how they are transported around the globe over the South Pacific Ocean. Different aerosol species are highlighted by color, including dust (orange), sea-salt (blue), nitrates (pink), sulfates (green), and carbon (red), with brighter regions corresponding to higher aerosol amounts. NASA's MODIS observations constrain regions with biomass burning as well as the aerosol optical depths in GEOS, capturing the prominent bushfires in Australia and transport of emitted aerosols well downstream over the South Pacific Ocean. Weather events including Hurricane Dorian in August – September 2019 and other tropical cyclones around the world, along with major fire events in South America and Indonesia in August - September 2019 are also shown. The local impacts of the Australian bushfires have been devastating to property and life in Australia while producing extreme air quality impacts throughout the region. As smoke from the massive fires has interacted with the global weather, the transport of smoke plumes around the global have accelerated through deep vertical transport into the upper troposphere and even the lowermost stratosphere, leading to long-range transport around the globe.

Methane is a powerful greenhouse gas that traps heat 28 times more effectively than carbon dioxide over a 100-year timescale. Concentrations of methane have increased by more than 150% since industrial activities and intensive agriculture began. After carbon dioxide, methane is responsible for about 20% of climate change in the twentieth century. Methane is produced under conditions where little to no oxygen is available. About 30% of methane emissions are produced by wetlands, including ponds, lakes and rivers. Another 20% is produced by agriculture, due to a combination of livestock, waste management and rice cultivation. Activities related to oil, gas, and coal extraction release an additional 30%. The remainder of methane emissions come from minor sources such as wildfire, biomass burning, permafrost, termites, dams, and the ocean. Scientists around the world are working to better understand the budget of methane with the ultimate goals of reducing greenhouse gas emissions and improving prediction of environmental change. For additional information, see the Global Methane Budget. The NASA SVS visualization presented here shows the complex patterns of methane emissions produced around the globe and throughout the year from the different sources described above. The visualization was created using output from the Global Modeling and Assimilation Office, GMAO, GEOS modeling system, developed and maintained by scientists at NASA. Wetland emissions were estimated by the LPJ-wsl model, which simulates the temperature and moisture dependent methane emission processes using a variety of satellite data to determine what parts of the globe are covered by wetlands. Other methane emission sources come from inventories of human activity. The height of Earth’s atmosphere and topography have been vertically exaggerated and appear approximately 50-times higher than normal in order to show the complexity of the atmospheric flow. As the visualization progresses, outflow from different source regions is highlighted. For example, high methane concentrations over South America are driven by wetland emissions while over Asia, emissions reflect a mix of agricultural and industrial activities. Emissions are transported through the atmosphere as weather systems move and mix methane around the globe. In the atmosphere, methane is eventually removed by reactive gases that convert it to carbon dioxide. Understanding the three-dimensional distribution of methane is important for NASA scientists planning observations that sample the atmosphere in very different ways. Satellites like GeoCarb, a planned geostationary mission to observe both carbon dioxide and methane, look down from space and will estimate the total number of methane molecules in a column of air. Aircraft, like those launched during NASA’s Arctic Boreal Vulnerability Experiment (ABOVE) sample the atmosphere along very specific flight lines, providing additional details about the processes controlling methane emissions at high latitudes. Atmospheric models help place these different types of measurements in context so that scientists can refine estimates of sources and sinks, understand the processes controlling them and reduce uncertainty in future projections of carbon-climate feedbacks.

Sulfur dioxide is an atmospheric pollutant that poses threats to both human health and the environment. High concentrations of sulfur dioxide irritate the eyes, nose, and lungs, and can result in temporary breathing impairment. It is also a precursor to sulfuric acid, a major constituent of acid rain.

This visualization, created using data from the Ozone Monitoring Instrument (OMI) onboard NASA’s Aura satellite, shows annual, average changes in sulfur dioxide concentrations from 2005 to 2017. Sulfur dioxide concentrations from volcanic (i.e., natural) sources have been removed.

Sulfur dioxide is produced by the combustion of coal, fuel oil, and gasoline (since these fuels contain sulfur), and in the oxidation of naturally occurring sulfur gases, such as in volcanic eruptions. The largest source of sulfur dioxide in the atmosphere is the burning of fossil fuels by power plants and other industrial facilities. National and regional rules to reduce emissions of sulfur dioxide can improve air quality.

An hyperwall show of OMI NO2 over the United States, updated using 2016 data.
For context and additional information: NASA Images Show Human Fingerprint on Global Air Quality

Using new, high-resolution global satellite maps of air quality indicators, NASA scientists tracked air pollution trends over the last decade in various regions and 195 cities around the globe. According to recent NASA research findings, the United States, Europe and Japan have improved air quality thanks to emission control regulations, while China, India and the Middle East, with their fast-growing economies and expanding industry, have seen more air pollution.

Scientists examined observations made from 2005 to 2014 by the Ozone Monitoring Instrument aboard NASA's Aura satellite. One of the atmospheric gases the instrument detects is nitrogen dioxide, a yellow-brown gas that is a common emission from cars, power plants and industrial activity. Nitrogen dioxide can quickly transform into ground-level ozone, a major respiratory pollutant in urban smog. Nitrogen dioxide hotspots, used as an indicator of general air quality, occur over most major cities in developed and developing nations.

The following visualizations include two types of data. The absolute concentrations show the concentration of tropospheric nitrogen dioxide, with blue and green colors denoting lower concentrations and orange and red areas indicating higher concentrations.

The second type of data is the trend data from 2005 to 2014, which shows the observed change in concentration over the ten-year period. Blue indicated an observed decrease in nitrogen dioxide, and orange indicates an observed increase. Please note that the range on the color bars (text is in white) changes from location to location in order to highlight features seen in the different geographic regions.

This animation shows the orbits of NASA's fleet of Earth observing spacecraft that are considered operational as of December 2019. The clouds used in this version are from a high resolution GEOS model run at 10 minute time steps interpolated down to the per-frame level. Changes to this version include: removal of Jason-2 and Jason-3 and the camera does not show DSCOVR within its view.

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Spacecraft included: Aqua Aura CALIPSO: Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation CYGNSS-1: Cyclone Global Navigation Satellite System 1 CYGNSS-2: Cyclone Global Navigation Satellite System 2 CYGNSS-3: Cyclone Global Navigation Satellite System 3 CYGNSS-4: Cyclone Global Navigation Satellite System 4 CYNGSS-5: Cyclone Global Navigation Satellite System 5 CYGNSS-6: Cyclone Global Navigation Satellite System 6 CYGNSS-7: Cyclone Global Navigation Satellite System 7 CYGNSS-8: Cyclone Global Navigation Satellite System 8 Cloudsat GPM: Global Precipitation Measurement GRACE-FO-1: Gravity Recovery and Climate Experiment Follow On-1 GRACE-FO-2: Gravity Recovery and Climate Experiment Follow On-2 ICESat-2 ISS: International Space Station Landsat 7 Landsat 8 OCO-2: Orbiting Carbon Observatory-2 SMAP: Soil Moisture Passive Active SORCE: Solar Radiation and Climate Experiment Suomi NPP: Suomi National Polar-orbiting Partnership Terra

Dazzling photographs and images from space of our planet’s nightlights have captivated public attention for decades. In such images, patterns are immediately seen based on the presence or absence of light: a distinct coastline, bodies of water recognizable by their dark silhouettes, and the faint tendrils of roads and highways emanating from the brilliant blobs of light that are our modern, well-lit cities.

For nearly 25 years, satellite images of Earth at night have served as a fundamental research tool, while also stoking public curiosity. These images paint an expansive and revealing picture, showing how natural phenomena light up the darkness and how humans have illuminated and shaped the planet in profound ways since the invention of the light bulb 140 years ago.