Publications by authors named "Robert Chatfield"

This study estimated long-term average ambient NO concentrations using TROPOspheric Monitoring Instrument (TROPOMI) tropospheric NO data and land use information at the spatial resolution of 500 m in California for the years 2018-2019. Our satellite-land use regression model demonstrated reasonably high predictive power with cross-validation (CV) R = 0.76, mean absolute error (MAE) = 1.

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Article Synopsis
  • The MAIAC algorithm produces column water vapor (CWV) data at a 1 km resolution using MODIS instruments from Aqua and Terra satellites, which have shown high validation against AERONET sun photometer data.
  • Recent research indicates that machine learning, specifically extreme gradient boosting (XGBoost), can enhance the accuracy of MAIAC aerosol optical depth (AOD) and potentially CWV measurements.
  • Using a robust spatiotemporal cross-validation method, XGBoost corrected significant measurement errors in CWV data, leading to notable reductions in root mean square error (RMSE) for both Terra and Aqua datasets, thereby improving satellite-derived CWV data for Earth science applications.
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Short-term air pollution episodes motivate improved understanding of the association between air pollution and acute morbidity and mortality episodes, and triggers required mitigation plans. A variety of methods have been employed to estimate exposure to air pollution episodes, including GIS-based dispersion models, interpolation between sparse monitoring sites, land-use regression models, optimization models, line- or area-dispersion plume models, and models using information from imaging satellites, often including land-use and meteorological variables. There has been increasing use of satellite-borne aerosol products for assessing short-term air quality events.

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Article Synopsis
  • Satellite-derived ground-level concentrations of PM2.5 in the Indo-Gangetic Plain were predicted using a random forest model, which outperformed a linear mixed effect model in accuracy and explained variance.
  • The RF model demonstrated that PM levels varied significantly by season and location, with winter showing the highest pollution levels, especially in the middle and lower regions of the IGP.
  • The study highlights that ground-level PM concentrations exceeded 110 μg/m annually, with extremely high levels in winter reaching over 170 μg/m in certain areas.
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In recent years, multipollutant approaches have been employed to investigate the association with health outcomes to better represent real-world conditions than more traditional analysis that considers a single pollutant. With regard to the exposure assessment of a mixture of air pollutants, it is critical to understand the spatial variability in multipollutant relations in order to assess their potential health implications. In this study, we investigated the spatial relations of multiple pollutant concentrations (i.

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Unlabelled: Airborne particulate matter (PM) is derived from diverse sources-natural and anthropogenic. Climate change processes and remote sensing measurements are affected by the PM properties, which are often lumped into homogeneous size fractions that show spatiotemporal variation. Since different sources are attributed to different geographic locations and show specific spatial and temporal PM patterns, we explored the spatiotemporal characteristics of the PM/PM ratio in different areas.

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We estimated daily ground-level PM2.5 concentrations combining Collection 6 deep blue (DB) Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD) data (10 km resolution) with land use regression in California, United States, for the period 2006-2012. The Collection 6 DB method for AOD provided more reliable data retrievals over California's bright surface areas than previous data sets.

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