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Papers by Ralph Kahn

Research paper thumbnail of Effects of COVID-19 lockdowns on fine particulate matter concentrations dataset

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.

Research paper thumbnail of Effects of COVID-19 lockdowns on fine particulate matter concentrations

Science Advances, Jun 25, 2021

Research paper thumbnail of Monthly Global Estimates of Fine Particulate Matter and Their Uncertainty

Environmental Science & Technology, Nov 1, 2021

Research paper thumbnail of Global Estimates of Ambient Fine Particulate Matter Concentrations from Satellite-Based Aerosol Optical Depth: Development and Application

Environmental Health Perspectives, Jun 1, 2010

Research paper thumbnail of Assessment of the impact of discontinuity in satellite instruments and retrievals on global PM2.5 estimates

Remote Sensing of Environment, Aug 1, 2023

Research paper thumbnail of Integrating and Interpreting Aerosol Observations and Models within the PARAGON Framework

Bulletin of the American Meteorological Society, Oct 1, 2004

Research paper thumbnail of Modulation of Atlantic aerosols by the Madden-Julian Oscillation

Journal of Geophysical Research, Aug 10, 2011

Research paper thumbnail of SPARTAN: a global network to evaluate and enhance satellite-based estimates of ground-level particulate matter for global health applications

Research paper thumbnail of Estimates of African Dust Deposition Along the Trans‐Atlantic Transit Using the Decadelong Record of Aerosol Measurements from CALIOP, MODIS, MISR, and IASI

Journal Of Geophysical Research: Atmospheres, Jul 27, 2019

Research paper thumbnail of Reducing Aerosol Forcing Uncertainty by Combining Models With Satellite and Within‐The‐Atmosphere Observations: A Three‐Way Street

Reviews of Geophysics, Jun 1, 2023

Research paper thumbnail of Constraining Aerosol Phase Function Using Dual‐View Geostationary Satellites

Journal Of Geophysical Research: Atmospheres, Oct 12, 2021

Research paper thumbnail of Scattering and absorbing aerosols in the climate system

Nature Reviews Earth & Environment

Research paper thumbnail of Comparisons between the distributions of dust and combustion aerosols in MERRA-2, FLEXPART and CALIPSO and implications for deposition freezing over wintertime Siberia

Research paper thumbnail of Calibrating Networks of Low-Cost Air Quality Sensors

Research paper thumbnail of Effects of COVID-19 lockdowns on fine particulate matter concentrations

Science Advances, 2021

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 .

Research paper thumbnail of Aerosol Properties in Cloudy Environments from Remote Sensing Observations: A Review of the Current State of Knowledge

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.

Research paper thumbnail of Large global variations in measured airborne metal concentrations driven by anthropogenic sources

Scientific Reports, 2020

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...

Research paper thumbnail of Supplementary material to "MISR Research Aerosol Algorithm: refinements for dark water retrievals

Research paper thumbnail of Space‐Based Observations for Understanding Changes in the Arctic‐Boreal Zone

Reviews of Geophysics, 2019

Research paper thumbnail of A satellite-based estimate of aerosol-cloud microphysical effects over the Arctic Ocean

Research paper thumbnail of Effects of COVID-19 lockdowns on fine particulate matter concentrations dataset

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.

Research paper thumbnail of Effects of COVID-19 lockdowns on fine particulate matter concentrations

Science Advances, Jun 25, 2021

Research paper thumbnail of Monthly Global Estimates of Fine Particulate Matter and Their Uncertainty

Environmental Science & Technology, Nov 1, 2021

Research paper thumbnail of Global Estimates of Ambient Fine Particulate Matter Concentrations from Satellite-Based Aerosol Optical Depth: Development and Application

Environmental Health Perspectives, Jun 1, 2010

Research paper thumbnail of Assessment of the impact of discontinuity in satellite instruments and retrievals on global PM2.5 estimates

Remote Sensing of Environment, Aug 1, 2023

Research paper thumbnail of Integrating and Interpreting Aerosol Observations and Models within the PARAGON Framework

Bulletin of the American Meteorological Society, Oct 1, 2004

Research paper thumbnail of Modulation of Atlantic aerosols by the Madden-Julian Oscillation

Journal of Geophysical Research, Aug 10, 2011

Research paper thumbnail of SPARTAN: a global network to evaluate and enhance satellite-based estimates of ground-level particulate matter for global health applications

Research paper thumbnail of Estimates of African Dust Deposition Along the Trans‐Atlantic Transit Using the Decadelong Record of Aerosol Measurements from CALIOP, MODIS, MISR, and IASI

Journal Of Geophysical Research: Atmospheres, Jul 27, 2019

Research paper thumbnail of Reducing Aerosol Forcing Uncertainty by Combining Models With Satellite and Within‐The‐Atmosphere Observations: A Three‐Way Street

Reviews of Geophysics, Jun 1, 2023

Research paper thumbnail of Constraining Aerosol Phase Function Using Dual‐View Geostationary Satellites

Journal Of Geophysical Research: Atmospheres, Oct 12, 2021

Research paper thumbnail of Scattering and absorbing aerosols in the climate system

Nature Reviews Earth & Environment

Research paper thumbnail of Comparisons between the distributions of dust and combustion aerosols in MERRA-2, FLEXPART and CALIPSO and implications for deposition freezing over wintertime Siberia

Research paper thumbnail of Calibrating Networks of Low-Cost Air Quality Sensors

Research paper thumbnail of Effects of COVID-19 lockdowns on fine particulate matter concentrations

Science Advances, 2021

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 .

Research paper thumbnail of Aerosol Properties in Cloudy Environments from Remote Sensing Observations: A Review of the Current State of Knowledge

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.

Research paper thumbnail of Large global variations in measured airborne metal concentrations driven by anthropogenic sources

Scientific Reports, 2020

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...

Research paper thumbnail of Supplementary material to "MISR Research Aerosol Algorithm: refinements for dark water retrievals

Research paper thumbnail of Space‐Based Observations for Understanding Changes in the Arctic‐Boreal Zone

Reviews of Geophysics, 2019

Research paper thumbnail of A satellite-based estimate of aerosol-cloud microphysical effects over the Arctic Ocean

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