Elizabeth Miglin | June 9, 2021

Researchers at the University of Iowa Technology Institute (ITI) have developed a new model to measure air pollution from soil using satellite data. 

Led by visiting ITI scholar Tong Sha, the study focused on nitrogen oxides (NOx) derived from soil (SNOx). Traditionally, NOx are thought of as emissions from combustion of fossil fuels however, scientists suspect SNOx may be increasingly responsible for poor ozone air quality, especially in agricultural areas. Although existing data to support this belief is lacking, the research started at the University of Iowa has led to a new assessment model which may yield more accurate estimates of SNOx. 

The new model updated the Weather Research and Forecasting simulator and chemistry, known as WRF-Chem, in order to improve an SNOx estimate scheme. With this, the researchers used an array of satellite sensors including the Global Precipitation Measurement to measure precipitation, Soil Moisture Active Passive to measure soil moisture and temperature, and others to show for the first time from space the increase of SNOx right after the fall of rain on dry soil. 

Although the research focused on rural California, its findings apply to rural cropland areas in Iowa and elsewhere. The study found around 40% of California’s NOx emissions are from soil and in the cropland areas SNOx emissions exceeded human-source emissions. Furthermore, the team found SNOx emissions are responsible for an additional 23% surface ozone concentration in California as a whole. 

The study was published on May 18th in the scientific journal Environmental Science & Technology.