Title:  Merged LEO-GEO Tropospheric Nitrogen Dioxide (tropNO2) Product for Air Quality Applications

Presenter(s): Thomas Ely

Date: 21 October 2024 12:05 pm – 12:35 pm ET

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About Speaker: Thomas Ely

Abstract: Air quality is a key societal issue and can be hard to predict in coastal cities such as New York City and Baltimore due to the effects of sea breeze. Air quality studies can benefit from more accurate retrievals of nitrogen dioxide (NO₂) from geostationary satellite sensors that show the transport and spatial distribution of pollution throughout the day. The objective of this project is to implement and test a methodology that can improve the quality of geostationary (GEO) satellite NO₂ data using low Earth orbit (LEO) satellite NO₂ data. This methodology uses the Kalman Filter algorithm to merge the two datasets in a process similar to data assimilation, except that the background model field uses data from a GEO satellite sensor, which in this case is NASA’s Tropospheric Emissions: Monitoring of Pollution (TEMPO) satellite sensor. LEO data from Sentinel5-Precursor TROPOspheric Monitoring Instrument (Sentinel-5P TROPOMI) serves as observational information. The Kalman Filter adds TROPOMI measurements to the background, weighting each dataset based on their respective uncertainties, which can mitigate uncertainties in each of the original datasets, resulting in a more accurate tropospheric NO₂ product that retains the high temporal resolution of TEMPO data. The merged TEMPO-TROPOMI product is compared against the Pandonia Global Network (PGN) ground-based tropospheric NO₂ column retrievals to evaluate the performance of the merged product compared to the original products. This project demonstrated the feasibility of implementing the Kalman Filter for merging satellite datasets and generated a new tropospheric NO₂ product that can be useful for local air-quality monitoring.The results are from the NOAA EPP/MSI CSC NERTO graduate internship project that was conducted with NOAA mentor Dr. Shobha Kondragunta of NOAA NESDIS. The NERTO aligns with NOAA CSC CESSRST-II’s goal to have students conduct NOAA mission-aligned research. The NERTO Merged LEO-GEO Tropospheric Nitrogen Dioxide Product also deepened the intern’s understanding of NOAA satellite product development and validation, as well as satellite sensor calibration.