TEMPO Air Quality Monitoring: Three Example Cases

On April 14 2025, strong winds triggered the formation of a huge dust storm in the U.S. central plains and fueled the ignition of grassland fires in Oklahoma. On the left, the nitrogen dioxide (NO₂) plumes originating from the grassland fires are tracked hour-by-hour by TEMPO. Smoke can be discerned from dust as a source since dust is not a source of NO₂. The animation on the right shows the ultraviolet (UV) aerosol index, which indicates particulates in the atmosphere that absorb UV light, such as dust and smoke.

On May 5 2025, TEMPO measured NO₂ emissions over the Twin Cities in the center of Minnesota during morning rush hour. The amount NO₂ increases in the air mid-day through early evening hours is illustrated by intense the red and black shaded areas at the Red River Valley along the North Dakota state line driven by emissions from the soils in agriculturally rich areas. Agricultural soil emissions are influenced by environmental factors like temperature and moisture as well as fertilizer application. Small fires and enhancements from mining activities can also be seen popping up across the region through the afternoon.

By measuring NO₂ and formaldehyde (HCHO), TEMPO can derive the presence of near-surface ozone. On Aug. 2 2024, over Houston, TEMPO observed exceptionally high ozone levels in the area. On the left, NO₂ builds up in the atmosphere over the city and over the Houston Ship Channel. On the right, formaldehyde levels are seen reaching a peak in the early afternoon. Formaldehyde is largely formed through the oxidation of hydrocarbons, an ingredient of ozone production, such as those that can be emitted by petrochemical facilities found in the Houston Ship Channel.