J. Ogren - Academia.edu (original) (raw)

Papers by J. Ogren

Research paper thumbnail of Enriched nitrate and ammonium in cloud condensation nuclei residues in continental cumulus humilis

Research paper thumbnail of Indian Ocean Experiment: An integrated analysis of the climate forcing and effects of the great Indo-Asian haze

Journal of Geophysical Research: Atmospheres, 2001

Every year, from December to April, anthropogenic haze spreads over most of the North Indian Ocea... more Every year, from December to April, anthropogenic haze spreads over most of the North Indian Ocean, and South and Southeast Asia. The Indian Ocean Experiment (INDOEX) documented this Indo-Asian haze at scales ranging from individual particles to its contribution to the regional climate forcing. This study integrates the multiplatform observations (satellites, aircraft, ships, surface stations, and balloons) with one-and fourdimensional models to derive the regional aerosol forcing resulting from the direct, the semidirect and the two indirect effects. The haze particles consisted of several inorganic and carbonaceous species, including absorbing black carbon clusters, fly ash, and mineral dust. The most striking result was the large loading of aerosols over most of the South Asian region and the North Indian Ocean. The January to March 1999 visible optical depths were about 0.5 over most of the continent and reached values as large as 0.2 over the equatorial Indian ocean due to long-range transport. The aerosol layer extended as high as 3 km. Black carbon contributed about 14% to the fine particle mass and 11% to the visible optical depth. The single-scattering albedo estimated by several independent methods was consistently around 0.9 both inland and over the open ocean. Anthropogenic sources contributed as much as 80% (_+10%) to the aerosol loading and the optical depth. The in situ data, which clearly support the existence of the first indirect effect (increased aerosol concentration producing more cloud drops with smaller effective radii), are used to develop a composite indirect effect scheme. The Indo-Asian aerosols impact the radiative forcing through a complex set of heating (positive forcing) and cooling (negative forcing) processes. Clouds and black carbon emerge as the major players. The dominant factor, however, is the large negative forcing (-20 +_ 4 W m -t) at the surface and the comparably large atmospheric heating. Regionally, the absorbing haze decreased the surface solar radiation by an amount comparable to 50% of the total ocean heat flux and nearly doubled the lower tropospheric solar heating. We demonstrate with a general circulation model how this additional heating significantly perturbs the tropical rainfall patterns and the hydrological cycle with implications to global climate.

Research paper thumbnail of Atmospheric Radiation Measurements Aerosol Intensive Operating Period: Comparison of aerosol scattering during coordinated flights

Journal of Geophysical Research, 2006

In May 2003, a Twin Otter airplane, equipped with instruments for making in situ measurements of ... more In May 2003, a Twin Otter airplane, equipped with instruments for making in situ measurements of aerosol optical properties, was deployed during the Atmospheric Radiation Measurements (ARM) Program's Aerosol Intensive Operational Period in Oklahoma. Several of the Twin Otter flights were flown in formation with an instrumented light aircraft (Cessna 172XP) that makes routine in situ aerosol profile flights over

Research paper thumbnail of Airborne Intrumentation Needs for Climate and Atmospheric Research

Bulletin of the American Meteorological Society, 2011

Research paper thumbnail of Racoro Extended-Term Aircraft Observations of Boundary Layer Clouds

Bulletin of the American Meteorological Society, 2012

A campaign involving 260 flight hours over more than 5 months provides the first extended-term ai... more A campaign involving 260 flight hours over more than 5 months provides the first extended-term aircraft dataset of a wide range of continental boundary layer clouds, and aerosol properties for climate studies.

Research paper thumbnail of Carbonaceous aerosols contributed by traffic and solid fuel burning at a polluted rural site in Northwestern England

Atmospheric Chemistry and Physics, 2011

The experiment presented in this paper was conducted at the Holme Moss site, which is located in ... more The experiment presented in this paper was conducted at the Holme Moss site, which is located in the southern Pennines region in Northwestern England during November-December 2006. The strong southwesterly wind during the experimental period, which enhanced the transport of urban pollutants from the conurbations of Greater Manchester and Liverpool, in addition to the seasonally increased nearby residential heating activities, made this site a receptor for pollutants from a range of sources. A factor analysis is applied to the mass spectra of organic matter (OM) measured by the Aerodyne Aerosol Mass Spectrometer (AMS) to attribute the pollutant sources. Besides the oxygenated organic aerosol (OOA), this site was found to contain a considerable fraction of primary organic aerosols (POA, mass fraction 50-70% within total mass of OM). The POA sources are attributed to be traffic emission and solid fuel burning, which are identified as hydrocarbon-like organic aerosol (HOA) and solid fuel organic aerosol (SFOA) respectively. There were strongly combined emissions of black carbon (BC) particles from both sources. The refractory BC component (rBC) was characterized by a single particle soot photometer. This site began to be influenced during the late morning by fresh traffic emissions, whereas solid fuel burning became dominant from late afternoon until night. A covariance analysis of rBC and POA was used to derive source specific emission factors of 1.61 µgHOA/µgrBC and 1.96 µgHOA/µgrBC. The absorbing properties of aerosols were characterized at multiple wavelengths (λ), and a stronger spectral dependence

Research paper thumbnail of Optical Properties and Climate Impacts of Tropospheric Aerosols that Undergo Long-Range Transport to the Arctic

Tropospheric aerosol particles undergo long range transport from the mid-latitudes to the Arctic ... more Tropospheric aerosol particles undergo long range transport from the mid-latitudes to the Arctic each winter and spring. Once in the Arctic, aerosols may impact the regional climate in several ways. Aerosols can affect climate directly by scattering and absorbing incoming solar radiation and indirectly by acting as cloud condensation nuclei and altering cloud properties. In addition, absorbing aerosol that is

Research paper thumbnail of Closure between Measured and Modeled Light Scattering Coefficients for Laboratory Test Aerosols and Dry Ambient Aerosols

Research paper thumbnail of CCN Studies at Different Locations: Relative Importance of Aerosol Composition, Hygroscopicity and Mixing State

The level of understanding of the effect of aerosol particles on clouds, via their ability to act... more The level of understanding of the effect of aerosol particles on clouds, via their ability to act as cloud condensation nuclei (CCN), is low. Further analysis of the physical and chemical parameters influencing CCN activation is required in order to quantify these effects and allow parameterizations of these processes in large scale models. Using results from several recent field campaigns

Research paper thumbnail of Intensive Airborne and Surface Measurements of Aerosol Microphysical and Optical Properties and Influences on Shortwave Radiation

Knowledge of pertinent aerosol optical properties (e.g. optical thickness, single scatter albedo,... more Knowledge of pertinent aerosol optical properties (e.g. optical thickness, single scatter albedo, backscatter fraction) is required to accurately calculate aerosol forcing. The Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) program has been systematically measuring aerosol properties at the surface and limited measurements aloft from light aircraft. Lidar and airborne in-situ measurements show that much of the aerosol at the ARM Southern Great Plains (SGP) site is aloft, often in layers decoupled from the surface, raising questions of the representativeness of surface aerosol properties for such calculations. Initial comparisons of aerosol optical thickness and aerosol extinction, two key aerosol properties, have revealed discrepancies among the lidar, Sun photometer, and airborne in situ measurements. Detailed measurements of aerosol optical properties are required to resolve these discrepancies, as well as to more completely characterize the aerosol optical, microphysical, and chemical properties at the surface and above the SGP site required for accurately computing radiative fluxes. Such well-characterized data would permit a more detailed evaluation of the performance of radiative transfer models to compute flux profiles and heating rates. In an effort to acquire these data, ARM will conduct an Aerosol Intensive Operational Period (IOP) in May 2003 at the ARM Southern Great Plains (SGP) site in north central Oklahoma. This experiment will use ground and airborne measurements of aerosol absorption, scattering, and extinction over the ARM SGP site to characterize the routine ARM aerosol measurements, and help resolve differences between measurements and models of diffuse irradiance at the surface. The assessments of aerosol optical thickness and aerosol absorption will be carried out in conjunction with measurements of downwelling direct and diffuse irradiance as a function of wavelength and altitude. The IOP will carry out a variety of closure experiments on aerosol optical properties and their radiative influence. Measurements of the aerosol chemical composition and size distribution will allow testing of the ability to reconstruct optical properties from these measurements. Additional effort will be directed toward measurement of cloud condensation nucleus concentration as a function of supersaturation and relating CCN concentration to aerosol composition and size distribution. This relation is central to description of the aerosol indirect effect. This poster describes the airborne and surface instruments that will be used in this IOP and the use of these data to conduct specific closure experiments relating to aerosol optical properties, radiative fluxes, and cloud condensation nuclei.

Research paper thumbnail of Enriched nitrate and ammonium in cloud condensation nuclei residues in continental cumulus humilis

Research paper thumbnail of Indian Ocean Experiment: An integrated analysis of the climate forcing and effects of the great Indo-Asian haze

Journal of Geophysical Research: Atmospheres, 2001

Every year, from December to April, anthropogenic haze spreads over most of the North Indian Ocea... more Every year, from December to April, anthropogenic haze spreads over most of the North Indian Ocean, and South and Southeast Asia. The Indian Ocean Experiment (INDOEX) documented this Indo-Asian haze at scales ranging from individual particles to its contribution to the regional climate forcing. This study integrates the multiplatform observations (satellites, aircraft, ships, surface stations, and balloons) with one-and fourdimensional models to derive the regional aerosol forcing resulting from the direct, the semidirect and the two indirect effects. The haze particles consisted of several inorganic and carbonaceous species, including absorbing black carbon clusters, fly ash, and mineral dust. The most striking result was the large loading of aerosols over most of the South Asian region and the North Indian Ocean. The January to March 1999 visible optical depths were about 0.5 over most of the continent and reached values as large as 0.2 over the equatorial Indian ocean due to long-range transport. The aerosol layer extended as high as 3 km. Black carbon contributed about 14% to the fine particle mass and 11% to the visible optical depth. The single-scattering albedo estimated by several independent methods was consistently around 0.9 both inland and over the open ocean. Anthropogenic sources contributed as much as 80% (_+10%) to the aerosol loading and the optical depth. The in situ data, which clearly support the existence of the first indirect effect (increased aerosol concentration producing more cloud drops with smaller effective radii), are used to develop a composite indirect effect scheme. The Indo-Asian aerosols impact the radiative forcing through a complex set of heating (positive forcing) and cooling (negative forcing) processes. Clouds and black carbon emerge as the major players. The dominant factor, however, is the large negative forcing (-20 +_ 4 W m -t) at the surface and the comparably large atmospheric heating. Regionally, the absorbing haze decreased the surface solar radiation by an amount comparable to 50% of the total ocean heat flux and nearly doubled the lower tropospheric solar heating. We demonstrate with a general circulation model how this additional heating significantly perturbs the tropical rainfall patterns and the hydrological cycle with implications to global climate.

Research paper thumbnail of Atmospheric Radiation Measurements Aerosol Intensive Operating Period: Comparison of aerosol scattering during coordinated flights

Journal of Geophysical Research, 2006

In May 2003, a Twin Otter airplane, equipped with instruments for making in situ measurements of ... more In May 2003, a Twin Otter airplane, equipped with instruments for making in situ measurements of aerosol optical properties, was deployed during the Atmospheric Radiation Measurements (ARM) Program's Aerosol Intensive Operational Period in Oklahoma. Several of the Twin Otter flights were flown in formation with an instrumented light aircraft (Cessna 172XP) that makes routine in situ aerosol profile flights over

Research paper thumbnail of Airborne Intrumentation Needs for Climate and Atmospheric Research

Bulletin of the American Meteorological Society, 2011

Research paper thumbnail of Racoro Extended-Term Aircraft Observations of Boundary Layer Clouds

Bulletin of the American Meteorological Society, 2012

A campaign involving 260 flight hours over more than 5 months provides the first extended-term ai... more A campaign involving 260 flight hours over more than 5 months provides the first extended-term aircraft dataset of a wide range of continental boundary layer clouds, and aerosol properties for climate studies.

Research paper thumbnail of Carbonaceous aerosols contributed by traffic and solid fuel burning at a polluted rural site in Northwestern England

Atmospheric Chemistry and Physics, 2011

The experiment presented in this paper was conducted at the Holme Moss site, which is located in ... more The experiment presented in this paper was conducted at the Holme Moss site, which is located in the southern Pennines region in Northwestern England during November-December 2006. The strong southwesterly wind during the experimental period, which enhanced the transport of urban pollutants from the conurbations of Greater Manchester and Liverpool, in addition to the seasonally increased nearby residential heating activities, made this site a receptor for pollutants from a range of sources. A factor analysis is applied to the mass spectra of organic matter (OM) measured by the Aerodyne Aerosol Mass Spectrometer (AMS) to attribute the pollutant sources. Besides the oxygenated organic aerosol (OOA), this site was found to contain a considerable fraction of primary organic aerosols (POA, mass fraction 50-70% within total mass of OM). The POA sources are attributed to be traffic emission and solid fuel burning, which are identified as hydrocarbon-like organic aerosol (HOA) and solid fuel organic aerosol (SFOA) respectively. There were strongly combined emissions of black carbon (BC) particles from both sources. The refractory BC component (rBC) was characterized by a single particle soot photometer. This site began to be influenced during the late morning by fresh traffic emissions, whereas solid fuel burning became dominant from late afternoon until night. A covariance analysis of rBC and POA was used to derive source specific emission factors of 1.61 µgHOA/µgrBC and 1.96 µgHOA/µgrBC. The absorbing properties of aerosols were characterized at multiple wavelengths (λ), and a stronger spectral dependence

Research paper thumbnail of Optical Properties and Climate Impacts of Tropospheric Aerosols that Undergo Long-Range Transport to the Arctic

Tropospheric aerosol particles undergo long range transport from the mid-latitudes to the Arctic ... more Tropospheric aerosol particles undergo long range transport from the mid-latitudes to the Arctic each winter and spring. Once in the Arctic, aerosols may impact the regional climate in several ways. Aerosols can affect climate directly by scattering and absorbing incoming solar radiation and indirectly by acting as cloud condensation nuclei and altering cloud properties. In addition, absorbing aerosol that is

Research paper thumbnail of Closure between Measured and Modeled Light Scattering Coefficients for Laboratory Test Aerosols and Dry Ambient Aerosols

Research paper thumbnail of CCN Studies at Different Locations: Relative Importance of Aerosol Composition, Hygroscopicity and Mixing State

The level of understanding of the effect of aerosol particles on clouds, via their ability to act... more The level of understanding of the effect of aerosol particles on clouds, via their ability to act as cloud condensation nuclei (CCN), is low. Further analysis of the physical and chemical parameters influencing CCN activation is required in order to quantify these effects and allow parameterizations of these processes in large scale models. Using results from several recent field campaigns

Research paper thumbnail of Intensive Airborne and Surface Measurements of Aerosol Microphysical and Optical Properties and Influences on Shortwave Radiation

Knowledge of pertinent aerosol optical properties (e.g. optical thickness, single scatter albedo,... more Knowledge of pertinent aerosol optical properties (e.g. optical thickness, single scatter albedo, backscatter fraction) is required to accurately calculate aerosol forcing. The Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) program has been systematically measuring aerosol properties at the surface and limited measurements aloft from light aircraft. Lidar and airborne in-situ measurements show that much of the aerosol at the ARM Southern Great Plains (SGP) site is aloft, often in layers decoupled from the surface, raising questions of the representativeness of surface aerosol properties for such calculations. Initial comparisons of aerosol optical thickness and aerosol extinction, two key aerosol properties, have revealed discrepancies among the lidar, Sun photometer, and airborne in situ measurements. Detailed measurements of aerosol optical properties are required to resolve these discrepancies, as well as to more completely characterize the aerosol optical, microphysical, and chemical properties at the surface and above the SGP site required for accurately computing radiative fluxes. Such well-characterized data would permit a more detailed evaluation of the performance of radiative transfer models to compute flux profiles and heating rates. In an effort to acquire these data, ARM will conduct an Aerosol Intensive Operational Period (IOP) in May 2003 at the ARM Southern Great Plains (SGP) site in north central Oklahoma. This experiment will use ground and airborne measurements of aerosol absorption, scattering, and extinction over the ARM SGP site to characterize the routine ARM aerosol measurements, and help resolve differences between measurements and models of diffuse irradiance at the surface. The assessments of aerosol optical thickness and aerosol absorption will be carried out in conjunction with measurements of downwelling direct and diffuse irradiance as a function of wavelength and altitude. The IOP will carry out a variety of closure experiments on aerosol optical properties and their radiative influence. Measurements of the aerosol chemical composition and size distribution will allow testing of the ability to reconstruct optical properties from these measurements. Additional effort will be directed toward measurement of cloud condensation nucleus concentration as a function of supersaturation and relating CCN concentration to aerosol composition and size distribution. This relation is central to description of the aerosol indirect effect. This poster describes the airborne and surface instruments that will be used in this IOP and the use of these data to conduct specific closure experiments relating to aerosol optical properties, radiative fluxes, and cloud condensation nuclei.