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Across Los Angeles and other monitored regions, the satellite\u2019s new maps separate nitrogen dioxide<\/a> into distinct plumes that were previously blended together.<\/p>\n Working from these observations, Zachary Fasnacht at NASA Goddard Space Flight Center<\/a> demonstrated that PACE can distinguish nearby emission sources rather than merging them into a single signal.<\/p>\n In those same scenes, each measurement pixel captures a much smaller area, allowing individual pollution streams to stand apart with greater clarity.<\/p>\n Even with that precision, the system still depends on favorable viewing conditions, setting clear limits on where and when the sharpest detail can be achieved.<\/p>\n How PACE learned<\/p>\n PACE\u2019s Ocean Color Instrument (OCI) was built to watch oceans, clouds, and aerosols, not to chase roadside exhaust.<\/p>\n Before launch, one study<\/a> showed that OCI retained enough light-pattern detail for software to recover nitrogen dioxide.<\/p>\n To turn that possibility into a product, researchers used machine learning \u2013 software that learns patterns from examples \u2013 trained against TROPOMI, a European satellite instrument that measures air pollutants from space.<\/p>\n Because TROPOMI already provides well-tested nitrogen dioxide readings across large regions, it supplied the reference values that allowed PACE to learn the gas at finer scale.<\/p>\n Why sharper pixels<\/p>\n When maps get sharper, a city block no longer looks like the whole city, and one plant no longer hides another.<\/p>\n Officials can trace highway corridors, ports, and industrial sites more directly because the gas signature stays tied to smaller areas.<\/p>\n This improves health research, since people breathe air near specific roads and smokestacks, not countywide averages.<\/p>\n \u201cThese data can potentially enable emissions estimates with reduced uncertainties and higher spatial resolution,\u201d wrote Fasnacht.<\/p>\n What the gas does<\/p>\n Burning fuel and wood releases nitrogen dioxide<\/a>, a reactive gas made during combustion, so tailpipes, power plants, and fires leave the same mark.<\/p>\n In sunlight, it helps build ground-level ozone, smog near the surface that irritates lungs and stresses crops.<\/p>\n Because that chemistry unfolds downwind, seeing where nitrogen dioxide starts gives forecasters a stronger clue about where ozone may rise.<\/p>\n The new product does not replace ground monitors, but it adds the broad view that street stations cannot supply.<\/p>\n Testing satellite accuracy<\/p>\n To check the maps, the team compared satellite readings with a ground network that measures nitrogen<\/a> dioxide directly from sunlight.<\/p>\n Those tests showed PACE and TROPOMI behaving similarly, with both tending to read about ten percent to 20 percent low.<\/p>\n At roughly a mile across, PACE could be checked against local conditions more precisely than the broader TROPOMI footprints.<\/p>\n Validation is still continuing, so the strongest claims today concern clear skies and places with stronger signals.<\/p>\n Data now open<\/p>\n NASA has already posted the new trace-gas dataset<\/a> on Earthdata, with coverage beginning March 5, 2024.<\/p>\n Along with nitrogen dioxide, the release includes ozone columns and quality flags that mark clouds, weak geometry, and poor radiance data.<\/p>\n Those warnings matter because bad viewing angles or leftover cloud can make a sharp-looking map misleading.<\/p>\n Easy public access means cities, health researchers, and air agencies can test uses quickly instead of waiting years.<\/p>\n Limits over water<\/p>\n Water remains harder than land because changing surface reflections can mimic or mask the gas signal in the light.<\/p>\n In the official document<\/a>, researchers caution that ocean scenes work best when nitrogen dioxide signals are strong.<\/p>\n Near the equator, instrument tilt changes can create odd features, and very slanted views over water raise errors further.<\/p>\n Those caveats do not erase the advance, but they show exactly where the next software releases must improve.<\/p>\n PACE with TEMPO<\/p>\n PACE does not work alone, because NASA\u2019s TEMPO<\/a> mission watches North America through every daylight hour.<\/p>\n Where PACE sharpens the picture once a day, TEMPO tracks how plumes move, spread, and change direction over time.<\/p>\n Using both together lets agencies see both the source pattern and the hourly drift that carries pollution into neighborhoods.<\/p>\n That combination could make satellite air data more useful for same-day decisions during rush-hour and industrial pollution<\/a> events.<\/p>\n The second payoff<\/p>\n The pollution product may also help the rest of PACE\u2019s science, even though the mission was not built for this job.<\/p>\n Nitrogen dioxide and ozone both absorb light, so measuring them directly can improve the cleanup applied before ocean color analysis.<\/p>\n That matters near coasts and cities, where polluted air can distort how satellites interpret surface reflections.<\/p>\n A mission launched for plankton and aerosols has therefore gained a second life as an air-quality tool.<\/p>\n What comes next for PACE<\/p>\n PACE has turned from an ocean-and-aerosol mission into a sharper pollution mapper that shows where dirty air begins and moves.<\/p>\n As validation expands and water algorithms improve, the satellite could become far more useful for daily health, planning, and emissions work.<\/p>\n The study is published in NASA Earthdata<\/a>.<\/p>\n \u2014\u2013<\/p>\n Like what you read?\u00a0Subscribe to our newsletter<\/a>\u00a0for engaging articles, exclusive content, and the latest updates.<\/p>\n Check us out on\u00a0EarthSnap<\/a>, a free app brought to you by\u00a0Eric Ralls<\/a>\u00a0and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"Researchers have found that NASA\u2019s PACE satellite can now detect nitrogen dioxide pollution at a fine enough 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