The Experts below are selected from a list of 1119732 Experts worldwide ranked by ideXlab platform
Julian D Marshall - One of the best experts on this subject based on the ideXlab platform.
-
remote sensing of exposure to no2 satellite versus ground based Measurement in a large urban area
ISEE Conference Abstracts, 2013Co-Authors: Matthew J Bechle, Dylan B Millet, Julian D MarshallAbstract:Background: Satellite remote sensing may be a powerful and useful tool for exploring spatial variability of air pollution within an urban area, particularly in countries or areas where direct measu...
-
remote sensing of exposure to no2 satellite versus ground based Measurement in a large urban area
Atmospheric Environment, 2013Co-Authors: Matthew J Bechle, Dylan B Millet, Julian D MarshallAbstract:Abstract Remote sensing may be a useful tool for exploring spatial variability of air pollution exposure within an urban area. To evaluate the extent to which satellite data from the Ozone Monitoring Instrument (OMI) can resolve urban-scale gradients in ground-level nitrogen dioxide (NO 2 ) within a large urban area, we compared estimates of surface NO 2 concentrations derived from OMI Measurements and US EPA ambient monitoring stations. OMI, aboard NASA's Aura satellite, provides daily afternoon (∼13:30 local time) Measurements of NO 2 tropospheric column abundance. We used scaling factors (surface-to-column ratios) to relate satellite column Measurements to ground-level concentrations. We compared 4138 sets of paired data for 25 monitoring stations in the South Coast Air Basin of California for all of 2005. OMI Measurements include more data gaps than the ground monitors (60% versus 5% of available data, respectively), owing to cloud contamination and imposed limits on pixel size. The spatial correlation between OMI columns and corrected in situ Measurements is strong ( r = 0.93 for annual average data), indicating that the within-urban spatial signature of surface NO 2 is well resolved by the satellite sensor. Satellite-based surface estimates employing scaling factors from an urban model provide a reliable measure (annual mean bias: −13%; seasonal mean bias: 2 . We also find that OMI provides good spatial density in the study region (average area [km 2 ] per Measurement: 730 for the satellite sensor vs. 1100 for the monitors). Our findings indicate that satellite observations of NO 2 from the OMI sensor provide a reliable measure of spatial variability in ground-level NO 2 exposure for a large urban area.
D Tanre - One of the best experts on this subject based on the ideXlab platform.
-
overview of the chemistry aerosol mediterranean experiment aerosol direct radiative forcing on the mediterranean climate charmex adrimed summer 2013 campaign
Atmospheric Chemistry and Physics, 2016Co-Authors: Marc Mallet, Jacques Pelon, Paola Formenti, Francois Dulac, Pierre Nabat, Jean Sciare, G Roberts, Gerard Ancellet, D TanreAbstract:The Chemistry-Aerosol Mediterranean Experiment (ChArMEx; http://charmex.lsce.ipsl.fr) is a collaborative research program federating international activities to investigate Mediterranean regional chemistry-climate interactions. A special observing period (SOP-1a) including intensive airborne Measurements was performed in the framework of the Aerosol Direct Radiative Forcing on the Mediterranean Climate (ADRIMED) project during the Mediterranean dry season over the western and central Mediterranean basins, with a focus on aerosol-radiation Measurements and their modeling. The SOP-1a took place from 11 June to 5 July 2013. Airborne Measurements were made by both the ATR-42 and F-20 French research aircraft operated from Sardinia (Italy) and instrumented for in situ and remote-sensing Measurements, respectively, and by sounding and drifting balloons, launched in Minorca. The experimental set-up also involved several Ground-Based Measurement sites on islands including two Ground-Based reference stations in Corsica and Lampedusa and secondary monitoring sites in Minorca and Sicily. Additional Measurements including lidar profiling were also performed on alert during aircraft operations at EARLINET/ACTRIS stations at Granada and Barcelona in Spain, and in southern Italy. Remote sensing aerosol products from satellites (MSG/SEVIRI, MODIS) and from the AERONET/PHOTONS network were also used. Dedicated meso-scale and regional modelling experiments were performed in relation to this observational effort. We provide here an overview of the different surface and aircraft observations deployed during the ChArMEx/ADRIMED period and of associated modeling studies together with an analysis of the synoptic conditions that determined the aerosol emission and transport. Meteorological conditions observed during this campaign (moderate temperatures and southern flows) were not favorable to produce high level of atmospheric pollutants nor intense biomass burning events in the region. However, numerous mineral dust plumes were observed during the campaign with main sources located in Morocco, Algeria and Tunisia, leading to aerosol optical depth (AOD) values ranging between 0.2 to 0.6 (at 440 nm) over the western and central Mediterranean basins. Associated aerosol extinction values measured on-board the ATR-42 within the dust plume show local maxima reaching up to 150 Mm−1. Non negligible aerosol extinction (about 50 Mm−1) was also been observed within the Marine Boundary Layer (MBL). By combining ATR-42 extinction, absorption and scattering Measurements, a complete optical closure has been made revealing excellent agreement with estimated optical properties. Associated calculations of the dust single scattering albedo (SSA) have been conducted, which show a moderate variability (from 0.90 to 1.00 at 530 nm). In parallel, active remote-sensing observations from the surface and onboard the F-20 aircraft suggest a complex vertical structure of particles and distinct aerosol layers with sea-salt and pollution located within the MBL, and mineral dust and/or aged north American smoke particles located above (up to 6–7 km in altitude). Aircraft and balloon-borne observations show particle size distributions characterized by large aerosols (> 10 μm in diameter) within dust plumes. In terms of shortwave (SW) direct forcing, in-situ surface and aircraft observations have been merged and used as inputs in 1-D radiative transfer codes for calculating the direct radiative forcing (DRF). Results show significant surface SW instantaneous forcing (up to −90 W m−2 at noon). Associated 3-D modeling studies from regional climate (RCM) and chemistry transport (CTM) models indicate a relatively good agreement for simulated AOD compared with Measurements/observations from the AERONET/PHOTONS network and satellite data, especially for long-range dust transport. Calculations of the 3-D SW (clear-sky) surface DRF indicate an average of about −10 to −20 W m−2 (for the whole period) over the Mediterranean Sea together with maxima (−50 W m−2) over northern Africa. The top of the atmosphere (TOA) DRF is shown to be highly variable within the domain, due to moderate absorbing properties of dust and changes in the surface albedo. Indeed, 3-D simulations indicate negative forcing over the Mediterranean Sea and Europe and positive forcing over northern Africa.
Jean Sciare - One of the best experts on this subject based on the ideXlab platform.
-
overview of the chemistry aerosol mediterranean experiment aerosol direct radiative forcing on the mediterranean climate charmex adrimed summer 2013 campaign
Atmospheric Chemistry and Physics, 2016Co-Authors: Marc Mallet, Jacques Pelon, Paola Formenti, Francois Dulac, Pierre Nabat, Jean Sciare, G Roberts, Gerard Ancellet, D TanreAbstract:The Chemistry-Aerosol Mediterranean Experiment (ChArMEx; http://charmex.lsce.ipsl.fr) is a collaborative research program federating international activities to investigate Mediterranean regional chemistry-climate interactions. A special observing period (SOP-1a) including intensive airborne Measurements was performed in the framework of the Aerosol Direct Radiative Forcing on the Mediterranean Climate (ADRIMED) project during the Mediterranean dry season over the western and central Mediterranean basins, with a focus on aerosol-radiation Measurements and their modeling. The SOP-1a took place from 11 June to 5 July 2013. Airborne Measurements were made by both the ATR-42 and F-20 French research aircraft operated from Sardinia (Italy) and instrumented for in situ and remote-sensing Measurements, respectively, and by sounding and drifting balloons, launched in Minorca. The experimental set-up also involved several Ground-Based Measurement sites on islands including two Ground-Based reference stations in Corsica and Lampedusa and secondary monitoring sites in Minorca and Sicily. Additional Measurements including lidar profiling were also performed on alert during aircraft operations at EARLINET/ACTRIS stations at Granada and Barcelona in Spain, and in southern Italy. Remote sensing aerosol products from satellites (MSG/SEVIRI, MODIS) and from the AERONET/PHOTONS network were also used. Dedicated meso-scale and regional modelling experiments were performed in relation to this observational effort. We provide here an overview of the different surface and aircraft observations deployed during the ChArMEx/ADRIMED period and of associated modeling studies together with an analysis of the synoptic conditions that determined the aerosol emission and transport. Meteorological conditions observed during this campaign (moderate temperatures and southern flows) were not favorable to produce high level of atmospheric pollutants nor intense biomass burning events in the region. However, numerous mineral dust plumes were observed during the campaign with main sources located in Morocco, Algeria and Tunisia, leading to aerosol optical depth (AOD) values ranging between 0.2 to 0.6 (at 440 nm) over the western and central Mediterranean basins. Associated aerosol extinction values measured on-board the ATR-42 within the dust plume show local maxima reaching up to 150 Mm−1. Non negligible aerosol extinction (about 50 Mm−1) was also been observed within the Marine Boundary Layer (MBL). By combining ATR-42 extinction, absorption and scattering Measurements, a complete optical closure has been made revealing excellent agreement with estimated optical properties. Associated calculations of the dust single scattering albedo (SSA) have been conducted, which show a moderate variability (from 0.90 to 1.00 at 530 nm). In parallel, active remote-sensing observations from the surface and onboard the F-20 aircraft suggest a complex vertical structure of particles and distinct aerosol layers with sea-salt and pollution located within the MBL, and mineral dust and/or aged north American smoke particles located above (up to 6–7 km in altitude). Aircraft and balloon-borne observations show particle size distributions characterized by large aerosols (> 10 μm in diameter) within dust plumes. In terms of shortwave (SW) direct forcing, in-situ surface and aircraft observations have been merged and used as inputs in 1-D radiative transfer codes for calculating the direct radiative forcing (DRF). Results show significant surface SW instantaneous forcing (up to −90 W m−2 at noon). Associated 3-D modeling studies from regional climate (RCM) and chemistry transport (CTM) models indicate a relatively good agreement for simulated AOD compared with Measurements/observations from the AERONET/PHOTONS network and satellite data, especially for long-range dust transport. Calculations of the 3-D SW (clear-sky) surface DRF indicate an average of about −10 to −20 W m−2 (for the whole period) over the Mediterranean Sea together with maxima (−50 W m−2) over northern Africa. The top of the atmosphere (TOA) DRF is shown to be highly variable within the domain, due to moderate absorbing properties of dust and changes in the surface albedo. Indeed, 3-D simulations indicate negative forcing over the Mediterranean Sea and Europe and positive forcing over northern Africa.
Matthew J Bechle - One of the best experts on this subject based on the ideXlab platform.
-
remote sensing of exposure to no2 satellite versus ground based Measurement in a large urban area
ISEE Conference Abstracts, 2013Co-Authors: Matthew J Bechle, Dylan B Millet, Julian D MarshallAbstract:Background: Satellite remote sensing may be a powerful and useful tool for exploring spatial variability of air pollution within an urban area, particularly in countries or areas where direct measu...
-
remote sensing of exposure to no2 satellite versus ground based Measurement in a large urban area
Atmospheric Environment, 2013Co-Authors: Matthew J Bechle, Dylan B Millet, Julian D MarshallAbstract:Abstract Remote sensing may be a useful tool for exploring spatial variability of air pollution exposure within an urban area. To evaluate the extent to which satellite data from the Ozone Monitoring Instrument (OMI) can resolve urban-scale gradients in ground-level nitrogen dioxide (NO 2 ) within a large urban area, we compared estimates of surface NO 2 concentrations derived from OMI Measurements and US EPA ambient monitoring stations. OMI, aboard NASA's Aura satellite, provides daily afternoon (∼13:30 local time) Measurements of NO 2 tropospheric column abundance. We used scaling factors (surface-to-column ratios) to relate satellite column Measurements to ground-level concentrations. We compared 4138 sets of paired data for 25 monitoring stations in the South Coast Air Basin of California for all of 2005. OMI Measurements include more data gaps than the ground monitors (60% versus 5% of available data, respectively), owing to cloud contamination and imposed limits on pixel size. The spatial correlation between OMI columns and corrected in situ Measurements is strong ( r = 0.93 for annual average data), indicating that the within-urban spatial signature of surface NO 2 is well resolved by the satellite sensor. Satellite-based surface estimates employing scaling factors from an urban model provide a reliable measure (annual mean bias: −13%; seasonal mean bias: 2 . We also find that OMI provides good spatial density in the study region (average area [km 2 ] per Measurement: 730 for the satellite sensor vs. 1100 for the monitors). Our findings indicate that satellite observations of NO 2 from the OMI sensor provide a reliable measure of spatial variability in ground-level NO 2 exposure for a large urban area.
Jacques Pelon - One of the best experts on this subject based on the ideXlab platform.
-
overview of the chemistry aerosol mediterranean experiment aerosol direct radiative forcing on the mediterranean climate charmex adrimed summer 2013 campaign
Atmospheric Chemistry and Physics, 2016Co-Authors: Marc Mallet, Jacques Pelon, Paola Formenti, Francois Dulac, Pierre Nabat, Jean Sciare, G Roberts, Gerard Ancellet, D TanreAbstract:The Chemistry-Aerosol Mediterranean Experiment (ChArMEx; http://charmex.lsce.ipsl.fr) is a collaborative research program federating international activities to investigate Mediterranean regional chemistry-climate interactions. A special observing period (SOP-1a) including intensive airborne Measurements was performed in the framework of the Aerosol Direct Radiative Forcing on the Mediterranean Climate (ADRIMED) project during the Mediterranean dry season over the western and central Mediterranean basins, with a focus on aerosol-radiation Measurements and their modeling. The SOP-1a took place from 11 June to 5 July 2013. Airborne Measurements were made by both the ATR-42 and F-20 French research aircraft operated from Sardinia (Italy) and instrumented for in situ and remote-sensing Measurements, respectively, and by sounding and drifting balloons, launched in Minorca. The experimental set-up also involved several Ground-Based Measurement sites on islands including two Ground-Based reference stations in Corsica and Lampedusa and secondary monitoring sites in Minorca and Sicily. Additional Measurements including lidar profiling were also performed on alert during aircraft operations at EARLINET/ACTRIS stations at Granada and Barcelona in Spain, and in southern Italy. Remote sensing aerosol products from satellites (MSG/SEVIRI, MODIS) and from the AERONET/PHOTONS network were also used. Dedicated meso-scale and regional modelling experiments were performed in relation to this observational effort. We provide here an overview of the different surface and aircraft observations deployed during the ChArMEx/ADRIMED period and of associated modeling studies together with an analysis of the synoptic conditions that determined the aerosol emission and transport. Meteorological conditions observed during this campaign (moderate temperatures and southern flows) were not favorable to produce high level of atmospheric pollutants nor intense biomass burning events in the region. However, numerous mineral dust plumes were observed during the campaign with main sources located in Morocco, Algeria and Tunisia, leading to aerosol optical depth (AOD) values ranging between 0.2 to 0.6 (at 440 nm) over the western and central Mediterranean basins. Associated aerosol extinction values measured on-board the ATR-42 within the dust plume show local maxima reaching up to 150 Mm−1. Non negligible aerosol extinction (about 50 Mm−1) was also been observed within the Marine Boundary Layer (MBL). By combining ATR-42 extinction, absorption and scattering Measurements, a complete optical closure has been made revealing excellent agreement with estimated optical properties. Associated calculations of the dust single scattering albedo (SSA) have been conducted, which show a moderate variability (from 0.90 to 1.00 at 530 nm). In parallel, active remote-sensing observations from the surface and onboard the F-20 aircraft suggest a complex vertical structure of particles and distinct aerosol layers with sea-salt and pollution located within the MBL, and mineral dust and/or aged north American smoke particles located above (up to 6–7 km in altitude). Aircraft and balloon-borne observations show particle size distributions characterized by large aerosols (> 10 μm in diameter) within dust plumes. In terms of shortwave (SW) direct forcing, in-situ surface and aircraft observations have been merged and used as inputs in 1-D radiative transfer codes for calculating the direct radiative forcing (DRF). Results show significant surface SW instantaneous forcing (up to −90 W m−2 at noon). Associated 3-D modeling studies from regional climate (RCM) and chemistry transport (CTM) models indicate a relatively good agreement for simulated AOD compared with Measurements/observations from the AERONET/PHOTONS network and satellite data, especially for long-range dust transport. Calculations of the 3-D SW (clear-sky) surface DRF indicate an average of about −10 to −20 W m−2 (for the whole period) over the Mediterranean Sea together with maxima (−50 W m−2) over northern Africa. The top of the atmosphere (TOA) DRF is shown to be highly variable within the domain, due to moderate absorbing properties of dust and changes in the surface albedo. Indeed, 3-D simulations indicate negative forcing over the Mediterranean Sea and Europe and positive forcing over northern Africa.
-
Overview of the Dust and Biomass-burning Experiment and African Monsoon Multidisciplinary Analysis Special Observing Period-0
Journal of Geophysical Research: Atmospheres, 2008Co-Authors: Jim M. Haywood, Jacques Pelon, Paola Formenti, N. Bharmal, M. Brooks, G. Capes, Patrick Chazette, C. Chou, S. Christopher, H. CoeAbstract:The African Monsoon Multidisciplinary Analysis (AMMA) is a major international campaign investigating far-reaching aspects of the African monsoon, climate and the hydrological cycle. A special observing period was established for the dry season (SOP0) with a focus on aerosol and radiation Measurements. SOP0 took place during January and February 2006 and involved several Ground-Based Measurement sites across west Africa. These were augmented by aircraft Measurements made by the Facility for Airborne Atmospheric Measurements (FAAM) aircraft during the Dust and Biomass-burning Experiment (DABEX), Measurements from an ultralight aircraft, and dedicated modeling efforts. We provide an overview of these Measurement and modeling studies together with an analysis of the meteorological conditions that determined the aerosol transport and link the results together to provide a balanced synthesis. The biomass burning aerosol was significantly more absorbing than that measured in other areas and, unlike industrial areas, the ratio of excess carbon monoxide to organic carbon was invariant, which may be owing to interaction between the organic carbon and mineral dust aerosol. The mineral dust aerosol in situ filter Measurements close to Niamey reveals very little absorption, while other Measurements and remote sensing inversions suggest significantly more absorption. The influence of both mineral dust and biomass burning aerosol on the radiation budget is significant throughout the period, implying that meteorological models should include their radiative effects for accurate weather forecasts and climate simulations. Generally, the operational meteorological models that simulate the production and transport of mineral dust show skill at lead times of 5 days or more. Climate models that need to accurately simulate the vertical profiles of both anthropogenic and natural aerosols to accurately represent the direct and indirect effects of aerosols appear to do a reasonable job, although the magnitude of the aerosol scattering is strongly dependent upon the emission data set.
