Vegetation & Ocean Monitoring

Agricultural soil NOx emissions and air quality

Aaron Naeger, TEMPO Deputy Program Applications Lead, University of Alabama in Huntsville / NASA-SPoRT

A portion of the non-standard operational time of TEMPO will be used for monitoring and assessing the influence of agricultural soil conditions and associated NOX emissions on trace gas concentrations (i.e., NO2 and O3) and air quality conditions over California. Although NOX emissions from fossil fuel sources have significantly reduced due to instituted policies in the state, field measurements reveal that agricultural soils are a major source of NOX in California's Central Valley. Recent evidence has shown that these biogenic NOX emissions likely play a much larger role in contributing to the atmospheric NOX throughout the state (Almaraz et al., 2018). Quantifying NO2 and O3 production due to the various NOX emission sources, including smoke, mobile, and agricultural soils, in California is extremely challenging using the current fleet of polar-orbiting sensors with limited overpasses per day over the region. The launch of the TEMPO spectrometer with high spatial and temporal resolution will provide high-quality retrievals of tropospheric NO2 and O3 profiles, which will permit more detailed attribution studies of NOX emissions over California. However, due to the highly fluctuating emissions that often occur during the daytime in the state, it will be very beneficial to monitor the region at an even higher temporal resolution down to 10 minutes in an effort to fully understand the evolving NOX emissions and associated NO2 and O3 concentrations. This enhanced monitoring capability will allow detailed process studies of how trace gases evolve with meteorology and surface and soil conditions in the state. The high-resolution TEMPO retrievals of NO2 and O3 will be used alongside soil moisture retrievals from the Soil Moisture Active Passive (SMAP) satellite to assess the diurnal cycle of soil NOX emissions, in relation to rainfall, irrigation schedule, and temperature, and impact on air quality in California. This study will utilize the California Irrigation Management Information System (CIMIS), which maintains over 145 weather stations near and within agricultural areas throughout the state for monitoring soil temperature and precipitation. Finally, the non-standard operations over California will encompass the Primary Target Area of Los Angeles from the Multi-Angle Imager for Aerosols (MAIA) satellite mission, which will promote future impactful air quality and public health studies in this region.

Almaraz, M., Bai, E. Wang, C., Trousdell, J. , Conley, S. Faloona, I. and Houltin,B.Z. Agriculture is a major source of NOX pollution in California. Sci. Adv. 2018, 4

Technical Contact: Dr. Aaron Naeger (
Responsible Official: Dr. Gary Jedlovec (
Page Curator: Paul Meyer (