Monthly regional PM<sub>2.5</sub> estimates for China, Europe, and North America for ... more Monthly regional PM<sub>2.5</sub> estimates for China, Europe, and North America for January-April 2018 to 2020 from the paper "Effects of COVID-19 lockdowns on fine particulate matter concentrations" published in Science Advances.
Satellite-derived PM 2.5 concentrations are produced and examined to assess the effects of COVID-... more Satellite-derived PM 2.5 concentrations are produced and examined to assess the effects of COVID-19 lockdowns on PM 2.5 .
Bulletin of the American Meteorological Society, 2021
Aerosol properties are fundamentally different near clouds than away from clouds. This paper revi... more Aerosol properties are fundamentally different near clouds than away from clouds. This paper reviews the current state of knowledge of aerosol properties in the near-low-cloud environment and quantitatively compares them with aerosols far from clouds, according to remote sensing observations. It interprets observations of aerosol properties from different sensors using satellite, aircraft, and ground-based observations. The correlation (and anticorrelation) between proximity to cloud and aerosol properties is discussed. Retrieval artifacts in the near-cloud environment are demonstrated and quantified for different sensor attributes and environmental conditions. Finally, the paper describes the possible corrections for near-cloud enhancement in remote sensing retrievals. This study is timely in view of science definition studies for NASA’s Aerosol, Cloud, Convection and Precipitation (ACCP) mission, which will also seek to directly link aerosol properties to nearby clouds.
Globally consistent measurements of airborne metal concentrations in fine particulate matter (PM2... more Globally consistent measurements of airborne metal concentrations in fine particulate matter (PM2.5) are important for understanding potential health impacts, prioritizing air pollution mitigation strategies, and enabling global chemical transport model development. PM2.5 filter samples (N ~ 800 from 19 locations) collected from a globally distributed surface particulate matter sampling network (SPARTAN) between January 2013 and April 2019 were analyzed for particulate mass and trace metals content. Metal concentrations exhibited pronounced spatial variation, primarily driven by anthropogenic activities. PM2.5 levels of lead, arsenic, chromium, and zinc were significantly enriched at some locations by factors of 100–3000 compared to crustal concentrations. Levels of metals in PM2.5 and PM10 exceeded health guidelines at multiple sites. For example, Dhaka and Kanpur sites exceeded the US National Ambient Air 3-month Quality Standard for lead (150 ng m−3). Kanpur, Hanoi, Beijing and D...
Monthly regional PM<sub>2.5</sub> estimates for China, Europe, and North America for ... more Monthly regional PM<sub>2.5</sub> estimates for China, Europe, and North America for January-April 2018 to 2020 from the paper "Effects of COVID-19 lockdowns on fine particulate matter concentrations" published in Science Advances.
Satellite-derived PM 2.5 concentrations are produced and examined to assess the effects of COVID-... more Satellite-derived PM 2.5 concentrations are produced and examined to assess the effects of COVID-19 lockdowns on PM 2.5 .
Bulletin of the American Meteorological Society, 2021
Aerosol properties are fundamentally different near clouds than away from clouds. This paper revi... more Aerosol properties are fundamentally different near clouds than away from clouds. This paper reviews the current state of knowledge of aerosol properties in the near-low-cloud environment and quantitatively compares them with aerosols far from clouds, according to remote sensing observations. It interprets observations of aerosol properties from different sensors using satellite, aircraft, and ground-based observations. The correlation (and anticorrelation) between proximity to cloud and aerosol properties is discussed. Retrieval artifacts in the near-cloud environment are demonstrated and quantified for different sensor attributes and environmental conditions. Finally, the paper describes the possible corrections for near-cloud enhancement in remote sensing retrievals. This study is timely in view of science definition studies for NASA’s Aerosol, Cloud, Convection and Precipitation (ACCP) mission, which will also seek to directly link aerosol properties to nearby clouds.
Globally consistent measurements of airborne metal concentrations in fine particulate matter (PM2... more Globally consistent measurements of airborne metal concentrations in fine particulate matter (PM2.5) are important for understanding potential health impacts, prioritizing air pollution mitigation strategies, and enabling global chemical transport model development. PM2.5 filter samples (N ~ 800 from 19 locations) collected from a globally distributed surface particulate matter sampling network (SPARTAN) between January 2013 and April 2019 were analyzed for particulate mass and trace metals content. Metal concentrations exhibited pronounced spatial variation, primarily driven by anthropogenic activities. PM2.5 levels of lead, arsenic, chromium, and zinc were significantly enriched at some locations by factors of 100–3000 compared to crustal concentrations. Levels of metals in PM2.5 and PM10 exceeded health guidelines at multiple sites. For example, Dhaka and Kanpur sites exceeded the US National Ambient Air 3-month Quality Standard for lead (150 ng m−3). Kanpur, Hanoi, Beijing and D...
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Papers by Ralph Kahn