Evaluation of the Sensing of Soil NOx Emissions: Preliminary Results

Nitrogen oxides (NO_x) play a crucial role in tropospheric chemistry. NOx influences the oxidizing capacity of the troposphere by reacting with hydroxyl radicals (OH) and then catalyzing the formation of ozone (O₃). This study focuses on the natural emission of soil NOx to determine if the puff of NOx emitted from the soil is visible by using SMAP, Sentinel 5 and GPM satellite data. The motivation for doing this work is to determine the impacts of soil NOx emissions on air quality. Methods of research began first with creating plots of SMAP (Soil Moisture Active Passive) soil moisture data, TROPOMI (TROPOspheric Monitoring Instrument) NO₂ data, and GPM (Global Precipitation Measurement) precipitation data for the month of July in 2018 over a specified midwestern United States region. These plots indicated that certain days when there is a rain event, both the soil moisture content and amount of NO₂ increased. To improve analysis accuracy, the TROPOMI dataset and SMAP dataset must be in the same spatial resolution to be able to make comparisons at the same pixel level. This was achieved by regridding the TROPOMI dataset to a standardized grid and then subsetting the SMAP dataset to extract data of interest. A correlation plot was then created as an attempt to verify the correlation of the study region. It was found that it is better to study NO₂ in smaller regions and that time series are needed to study how these smaller regions are correlated. The processing of all work was done under high performance computing in python.