Comparison of aerosol optical depth product from MODIS product collection 6.1 and AERONET in the western United States

Authors: EIBEDINGIL, IYASU - University Of Texas - El Paso; GILL, THOMAS - University Of Texas - El Paso; Van Pelt, Robert - Scott; TONG, DANIEL - George Mason University

Submitted to: Remote Sensing
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/10/2021
Publication Date: 6/13/2021
Citation: Eibedingil, I.G., Gill, T.E., Van Pelt, R.S., Tong, D.Q. 2021. Comparison of aerosol optical depth product from MODIS product collection 6.1 and AERONET in the western United States. Remote Sensing. 13(12):2316. https://doi.org/10.3390/rs13122316.
DOI: https://doi.org/10.3390/rs13122316

Interpretive Summary: Dust in the atmosphere has been increasing across much of the western United States. This dust is the most visual evidence of increasing soil erosion with the resulting loss of soil productivity and is a hazard to human health and safety. Every year, atmospheric dust impacts commerce and dust-related illnesses cost billions of dollars in the United States alone. Atmospheric dust is measured in units of Aerosol Optical Depth (AOD). In the western United States, AOD is measured by the Moderate Resolution Imaging Spectroradiometer (MODIS) Deep Blue (DB) and Dark Target (DT) product collection 6.1 obtained from the Aqua and Terra satellites and from ground-based sensors in the Aerosol Robotic Network (AERONET). Scientists from the University of Texas at El Paso, George Mason University, and the United States Department of Agriculture Agricultural Research Service Wind Erosion and Water Conservation Research Unit compared AOD measurements from these different instruments and perspectives to find if one set of measurements agreed with the other set for several dates from 2003 to 2017. We found good agreement in general but the MODIS-based measurement generally over-estimated the AOD when compared to AERONET-based measurements. It is hoped these findings will result in better algorithms to convert satellite spectral data to measurements of AOD.

Technical Abstract: Recent observations reveal that dust storms are increasing in the western United States, posing imminent risks to the environment, public health, safety, and the economy. Much of the observational evidence has been obtained from ground-based platforms and visual interpretation of satellite imagery from limited regions. Comprehensive satellite-based observations of long-term aerosol records are still lacking. In an effort to develop such a satellite aerosol dataset, we compared and evaluated the Aerosol Optical Depth (AOD) from Moderate Resolution Imaging Spectroradiometer (MODIS) Deep Blue (DB) and Dark Target (DT) product collection 6.1 with Aerosol Robotic Network (AERONET) in the western United States (bounded by -92o meridian in the east). We examined the seasonal and monthly average number of MODIS Aqua DB AOD retrievals per 0.1o x 0.1o from January 2003 to December 2017 across the region’s different topographic, climatic, and land cover conditions. Springtime saw the highest number of AOD retrievals across the southwest, triggered by its arid and semi-arid climate. The seasonality and concentrations of aerosol loadings were different across the AERONET stations, largely influenced by geographical locations, weather and climate factors, elevation, and land use/land cover conditions. The majority of collocating domains of AOD from Aqua sensor showed a better correlation with AERONET AOD than did AOD from Terra, and the correlation coefficients exhibited large regional variability across the study area. In general, the majority of the stations revealed significant correlation between MODIS and AERONET AOD at all spatiotemporal aggregating domains, although MODIS generally overestimated AOD compared to AERONET.