Satellite NO 2 trends reveal pervasive impacts of wildfire and soil emissions across California landscapes

Bibliographic Data

ID15548241
AuthorsYurun Wang (0000-0003-4536-2227, University of California, Davis), I C Faloona (0000-0001-7296-9046, University of California, Davis, corresponding author), Benjamin Z Houlton (0000-0002-1414-0261, Cornell University)
Year2023
Volume18
Issue9
Pages094032-094032
Publication date2023-08-01
Open AccessYes
TypeARTICLE
VenueEnvironmental Research Letters (JOURNAL)
Journal identifiersISSN: 1748-9326 • E-ISSN: 1748-9326
PublisherIOP Publishing (PUBLISHER • GB)
DOI10.1088/1748-9326/acec5f
OpenAlexW4385448548
LanguageEN
Citations received1
References cited61

Nitrogen dioxide (NO 2 ) plays a pivotal role in the production of secondary pollutants, most importantly ozone (O 3 ) and particulate matter. Regulatory controls have greatly reduced NO 2 in cities, where most of the surface monitoring occurs, but the change in rural environments is less certain. Here, we present summertime (June–September) spatio-temporal patterns of NO 2 concentrations using satellite and ground observations across California from 2009–2020, quantifying the differences in NO 2 trends for five distinct land cover classes: urban, forests, croplands, scrublands (shrublands, savannas, and grasslands), and barren (minimally vegetated) lands. Over urban environments, NO 2 columns exhibited continued but weakening downward trends (−3.7 ± 0.3%a −1 ), which agree fairly well with contemporaneous trends estimated from the surface air quality network (−4.5 ± 0.5%a −1 ). In rural (i.e., non-urban) parts of the state, however, secular trends are insignificant (0.0–0.4 ± 0.4%a −1 ) or in the case of remote forests are rapidly on the rise (+4.2 ± 1.2%a −1 ). Sorting the NO 2 columns by air temperature and soil moisture reveals relationships that are commensurate with extant parameterizations but do indicate a stronger temperature dependence. We further find that rapidly rising temperatures and, to a lesser extent, decreasing precipitation in response to climate change are acting to increase soil NO x emissions, explaining about one-third of the observed NO 2 rise in non-urban regions across California. Finally, we show that these trends, or their absence, can be attributed predominantly to the dramatic rise in wildfire frequency, especially since the turn of the 21st century

Air quality index · Atmospheric sciences · Climate change · Ecosystem · Geography · Grassland · Meteorology · Particulates · Physical geography · Precipitation · Shrubland · Vegetation (pathology · Atmospheric and Environmental Gas Dynamics · Atmospheric chemistry and aerosols · Environmental Science · Fire effects on ecosystems · Ecology · Geology

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