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Nitrogen Dioxide Trends

Nitrogen dioxide (NO2) is an Environmental Protection Agency (EPA) criteria pollutant. It contributes to the formation of ground-level ozone. Anthropogenic sources of NO2 include power plants and transportation. Aura's Ozone Monitoring Instrument (OMI) instrument observe the trends in nitrogen dioxide.

Aura OMI Nitrogen dioxide measurements 2009
The Aura OMI Nitrogen dioxide 2007 - 2005 annual measurements show decreases in US due to greater controls on car and power plant NOx emissions. Increases in Asia due to increased emissions (power plants and transportation).

Nitrogen dioxide in Southern California is more concentrated in more densely populated urban areas. NO2 forms quickly from emissions from cars, trucks and buses, power plants, and off-road equipment. In addition to contributing to the formation of ground-level ozone, and fine particle pollution, NO2 is linked with a number of adverse effects, particularly affecting the respiratory system.

Aura OMI Tropospheric column NO2 concentrations
Tropospheric column NO2 concentrations (molecules/cm2) from the Ozone Monitoring Instrument (OMI) over the South Coast region of California from one day, August 1, 2008.
Aura OMI Tropospheric column NO2 concentrations
OMI NO2 columns averaged over summer months (Jun-Aug) for the years 2005-2008 at 0.025 degree resolution. The satellite's 16 day repeat pattern provides daily measurements which partially overlap allowing an area-weighted average to produce a higher resolution image.

Weekdays
Weekends
Aura OMI nitrogen dioxide (2005 Weekdays)
Aura OMI nitrogen dioxide (2005 Weekdays)
Aura OMI nitrogen dioxide (2005 Weekends)
Aura OMI nitrogen dioxide (2005 Weekends)
Aura OMI nitrogen dioxide (2005 Weekdays)
Aura OMI nitrogen dioxide (2005 Weekdays)
Aura OMI nitrogen dioxide (2005 Weekends)
Aura OMI nitrogen dioxide (2005 Weekends)
Weekdays
Weekends

Before and After

Emission Reductions Show Results

Weekday and Weekend Comparison

Over the past several years, California has enforced aggressive air quality regulations. Results of this action can be seen in Aura's OMI imagery which shows that decreases in nitrogen dioxide (NO2) columns over the 4 years 2005-2008 approach 40%, almost the same as the weekend decrease observed in 2005. Vehicles have a much smaller impact on local air quality than they did 20 years ago, but their emissions of heattrapping gases have continue. Mobile sources including passenger vehicles account for approximately half of California's global warming pollution.

Air Pollution Controls for Summer Surface Ozone

Ozone Monitoring Instrument (OMI) measurements of formaldehyde (HCHO) and nitrogen dioxide (NO2), and the ratio of HCHO to NO2 show how the data can be used to develop effective strategies to improve air quality.

Aura OMI Air Pollution Controls for Summer Surface Ozone
OMI measures formaldehyde (HCHO) and nitrogen dioxide (NO2), and the ratio of HCHO to NO2 for August 2005.

Harmful levels of surface ozone can form through a complex series of reactions involving volatile organic compounds (VOCs) and nitrogen oxides (NOx) in the presence of sunlight. If the ratio HCHO/NO2 is less than 1 (e.g., Los Angeles, Chicago), ozone will decrease when emissions of anthropogenic VOCs are reduced. If the ratio is greater than 2, ozone will decrease when NOx emissions are reduced. Natural VOCs from trees are so high in the eastern United States that reducing NOx emissions is the effective strategy to improve air quality.

10.2009

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OMI

Aura’s Ozone Monitoring Instrument (OMI) instrument can distinguish between aerosol types, such as smoke, dust, and sulfates, and measures cloud pressure and coverage, which provides data to derive tropospheric ozone.…

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