Correlation of aerosol mass near the ground with aerosol optical depth during two seasons in Munich

Abstract. We document and evaluate the aerosol schemes as implemented in the physical and Earth system models, the Global Coupled 3.1 configuration of the Hadley Centre Global Environment Model version 3 (HadGEM3-GC3.1) and the United Kingdom Earth System Model (UKESM1), which are contributing to the sixth Coupled Model Intercomparison Project (CMIP6). The simulation of aerosols in the present-day period of the historical ensemble of these models is evaluated against a range of observations. Updates to the aerosol microphysics scheme are documented as well as differences in the aerosol representation between the physical and Earth system configurations. The additional Earth system interactions included in UKESM1 lead to differences in the emissions of natural aerosol sources such as dimethyl sulfide, mineral dust and organic aerosol and subsequent evolution of these species in the model. UKESM1 also includes a stratospheric–tropospheric chemistry scheme which is fully coupled to the aerosol scheme, while GC3.1 employs a simplified aerosol chemistry mechanism driven by prescribed monthly climatologies of the relevant oxidants. Overall, the simulated speciated aerosol mass concentrations compare reasonably well with observations. Both models capture the negative trend in sulfate aerosol concentrations over Europe and the eastern United States of America (US) although the models tend to underestimate sulfate concentrations in both regions. Interactive emissions of biogenic volatile organic compounds in UKESM1 lead to an improved agreement of organic aerosol over the US. Simulated dust burdens are similar in both models despite a 2-fold difference in dust emissions. Aerosol optical depth is biased low in dust source and outflow regions but performs well in other regions compared to a number of satellite and ground-based retrievals of aerosol optical depth. Simulated aerosol number concentrations are generally within a factor of 2 of the observations, with both models tending to overestimate number concentrations over remote ocean regions, apart from at high latitudes, and underestimate over Northern Hemisphere continents. Finally, a new primary marine organic aerosol source is implemented in UKESM1 for the first time. The impact of this new aerosol source is evaluated. Over the pristine Southern Ocean, it is found to improve the seasonal cycle of organic aerosol mass and cloud droplet number concentrations relative to GC3.1 although underestimations in cloud droplet number concentrations remain. This paper provides a useful characterisation of the aerosol climatology in both models and will facilitate understanding in the numerous aerosol–climate interaction studies that will be conducted as part of CMIP6 and beyond.

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A low-cost monitor for simultaneous measurement of fine particulate matter and aerosol optical depth – Part 1: Specifications and testing

Atmospheric Measurement Techniques ◽

10.5194/amt-12-5431-2019 ◽

2019 ◽

Vol 12 (10) ◽

pp. 5431-5441 ◽

Cited By ~ 4

Author(s):

Eric A. Wendt ◽

Casey W. Quinn ◽

Daniel D. Miller-Lionberg ◽

Jessica Tryner ◽

Christian L'Orange ◽

...

Keyword(s):

Particulate Matter ◽

Aerosol Optical Depth ◽

Optical Depth ◽

Low Cost ◽

Fine Particulate Matter ◽

Ground Level ◽

Aerosol Mass ◽

Fine Particulate ◽

The Cost ◽

Equivalent Method

Abstract. Globally, fine particulate matter (PM2.5) air pollution is a leading contributor to death, disease, and environmental degradation. Satellite-based measurements of aerosol optical depth (AOD) are used to estimate PM2.5 concentrations across the world, but the relationship between satellite-estimated AOD and ground-level PM2.5 is uncertain. Sun photometers measure AOD from the Earth's surface and are often used to improve satellite data; however, reference-grade photometers and PM2.5 monitors are expensive and rarely co-located. This work presents the development and validation of the aerosol mass and optical depth (AMOD) sampler, an inexpensive and compact device that simultaneously measures PM2.5 mass and AOD. The AMOD utilizes a low-cost light-scattering sensor in combination with a gravimetric filter measurement to quantify ground-level PM2.5. Aerosol optical depth is measured using optically filtered photodiodes at four discrete wavelengths. Field validation studies revealed agreement within 10 % for AOD values measured between co-located AMOD and AErosol RObotics NETwork (AERONET) monitors and for PM2.5 mass measured between co-located AMOD and EPA Federal Equivalent Method (FEM) monitors. These results demonstrate that the AMOD can quantify AOD and PM2.5 accurately at a fraction of the cost of existing reference monitors.

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Aerosol optical properties in the southeastern United States in summer – Part 2: Sensitivity of aerosol optical depth to relative humidity and aerosol parameters

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-5009-2016 ◽

2016 ◽

Vol 16 (8) ◽

pp. 5009-5019 ◽

Cited By ~ 25

Author(s):

Charles A. Brock ◽

Nicholas L. Wagner ◽

Bruce E. Anderson ◽

Andreas Beyersdorf ◽

Pedro Campuzano-Jost ◽

...

Keyword(s):

United States ◽

Refractive Index ◽

Relative Humidity ◽

Aerosol Optical Depth ◽

Optical Depth ◽

Mixed Boundary ◽

Southeastern United States ◽

Geometric Standard Deviation ◽

Aerosol Mass ◽

Southeastern Us

Abstract. Aircraft observations of meteorological, trace gas, and aerosol properties were made between May and September 2013 in the southeastern United States (US). Regionally representative aggregate vertical profiles of median and interdecile ranges of the measured parameters were constructed from 37 individual aircraft profiles made in the afternoon when a well-mixed boundary layer with typical fair-weather cumulus was present (Wagner et al., 2015). We use these 0–4 km aggregate profiles and a simple model to calculate the sensitivity of aerosol optical depth (AOD) to changes in dry aerosol mass, relative humidity, mixed-layer height, the central diameter and width of the particle size distribution, hygroscopicity, and dry and wet refractive index, while holding the other parameters constant. The calculated sensitivity is a result of both the intrinsic sensitivity and the observed range of variation in these parameters. These observationally based sensitivity studies indicate that the relationship between AOD and dry aerosol mass in these conditions in the southeastern US can be highly variable and is especially sensitive to relative humidity (RH). For example, calculated AOD ranged from 0.137 to 0.305 as the RH was varied between the 10th and 90th percentile profiles with dry aerosol mass held constant. Calculated AOD was somewhat less sensitive to aerosol hygroscopicity, mean size, and geometric standard deviation, σg. However, some chemistry–climate models prescribe values of σg substantially larger than we or others observe, leading to potential high biases in model-calculated AOD of ∼  25 %. Finally, AOD was least sensitive to observed variations in dry and wet aerosol refractive index and to changes in the height of the well-mixed surface layer. We expect these findings to be applicable to other moderately polluted and background continental air masses in which an accumulation mode between 0.1–0.5 µm diameter dominates aerosol extinction.

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Modelled and observed changes in aerosols and surface solar radiation over Europe between 1960 and 2009

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-13457-2015 ◽

2015 ◽

Vol 15 (9) ◽

pp. 13457-13513 ◽

Cited By ~ 3

Author(s):

S. T. Turnock ◽

D. V. Spracklen ◽

K. S. Carslaw ◽

G. W. Mann ◽

M. T. Woodhouse ◽

...

Keyword(s):

Solar Radiation ◽

Aerosol Optical Depth ◽

Optical Depth ◽

Radiative Forcing ◽

Sulfate Aerosol ◽

Anthropogenic Aerosols ◽

Surface Solar Radiation ◽

Aerosol Mass ◽

The Impact ◽

Aerosol Radiative

Abstract. Substantial changes in anthropogenic aerosols and precursor gas emissions have occurred over recent decades due to the implementation of air pollution control legislation and economic growth. The response of atmospheric aerosols to these changes and the impact on climate are poorly constrained, particularly in studies using detailed aerosol chemistry climate models. Here we compare the HadGEM3-UKCA coupled chemistry-climate model for the period 1960 to 2009 against extensive ground based observations of sulfate aerosol mass (1978–2009), total suspended particle matter (SPM, 1978–1998), PM10 (1997–2009), aerosol optical depth (AOD, 2000–2009) and surface solar radiation (SSR, 1960–2009) over Europe. The model underestimates observed sulfate aerosol mass (normalised mean bias factor (NMBF) = −0.4), SPM (NMBF = −0.9), PM10 (NMBF = −0.2) and aerosol optical depth (AOD, NMBF = −0.01) but slightly overpredicts SSR (NMBF = 0.02). Trends in aerosol over the observational period are well simulated by the model, with observed (simulated) changes in sulfate of −68% (−78%), SPM of −42% (−20%), PM10 of −9% (−8%) and AOD of −11% (−14%). Discrepancies in the magnitude of simulated aerosol mass do not affect the ability of the model to reproduce the observed SSR trends. The positive change in observed European SSR (5%) during 1990–2009 ("brightening") is better reproduced by the model when aerosol radiative effects (ARE) are included (3%), compared to simulations where ARE are excluded (0.2%). The simulated top-of-the-atmosphere aerosol radiative forcing over Europe under all-sky conditions increased by 3 W m−2 during the period 1970–2009 in response to changes in anthropogenic emissions and aerosol concentrations.

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Description and evaluation of aerosol in UKESM1 and HadGEM3-GC3.1 CMIP6 historical simulations

10.5194/gmd-2019-357 ◽

2020 ◽

Cited By ~ 9

Author(s):

Jane P. Mulcahy ◽

Colin Johnson ◽

Colin G. Jones ◽

Adam C. Povey ◽

Catherine E. Scott ◽

...

Keyword(s):

Aerosol Optical Depth ◽

Optical Depth ◽

Dimethyl Sulfide ◽

Cloud Droplet ◽

Organic Aerosol ◽

Tropospheric Chemistry ◽

Earth System ◽

Aerosol Mass ◽

The Impact ◽

Aerosol Source

Abstract. We document and evaluate the aerosol schemes as implemented in the physical and Earth system models, HadGEM3-GC3.1 (GC3.1) and UKESM1, which are contributing to the 6th Coupled Model Intercomparison Project (CMIP6). The simulation of aerosols in the present-day period of the historical ensemble of these models is evaluated against a range of observations. Updates to the aerosol microphysics scheme are documented as well as differences in the aerosol representation between the physical and Earth system configurations. The additional Earth-system interactions included in UKESM1 leads to differences in the emissions of natural aerosol sources such as dimethyl sulfide, mineral dust and organic aerosol and subsequent evolution of these species in the model. UKESM1 also includes a stratospheric-tropospheric chemistry scheme which is fully coupled to the aerosol scheme, while GC3.1 employs a simplified aerosol chemistry mechanism driven by prescribed monthly climatologies of the relevant oxidants. Overall, the simulated speciated aerosol mass concentrations compare reasonably well with observations. Both models capture the negative trend in sulfate aerosol concentrations over Europe and the eastern United States of America (US) although the models tend to underestimate the sulfate concentrations in both regions. Interactive emissions of biogenic volatile organic compounds in UKESM1 lead to an improved agreement of organic aerosol over the US. Simulated dust burdens are similar in both models despite a 2-fold difference in dust emissions. Aerosol optical depth is biased low in dust source and outflow regions but performs well in other regions compared to a number of satellite and ground-based retrievals of aerosol optical depth. Simulated aerosol number concentrations are generally within a factor of 2 of the observations with both models tending to overestimate number concentrations over remote ocean regions, apart from at high latitudes, and underestimate over Northern Hemisphere continents. Finally, UKESM1 includes for the first time a representation of a primary marine organic aerosol source. The impact of this new aerosol source is evaluated. Over the pristine Southern Ocean, it is found to improve the seasonal cycle of organic aerosol mass and cloud droplet number concentrations relative to GC3.1 although underestimations in cloud droplet number concentrations remain. This paper provides a useful characterization of the aerosol climatology in both models facilitating the understanding of the numerous aerosol-climate interaction studies that will be conducted as part of CMIP6 and beyond.

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Retrieval of aerosol mass load (PM<sub>10</sub>) from MERIS/Envisat top of atmosphere spectral reflectance measurements

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-3-5429-2010 ◽

2010 ◽

Vol 3 (6) ◽

pp. 5429-5467 ◽

Cited By ~ 2

Author(s):

G. J. Rohen ◽

W. von Hoyningen-Huene ◽

A. Kokhanovsky ◽

T. Dinter ◽

M. Vountas ◽

...

Keyword(s):

Particulate Matter ◽

Aerosol Optical Depth ◽

Optical Depth ◽

Size Distribution Function ◽

Correlation Factor ◽

Urban Site ◽

Boundary Layer Height ◽

Aerosol Mass ◽

Mass Load ◽

Log Normal

Abstract. A retrieval of particulate matter concentration (PM10) from satellite data is presented as well as improvements of the aerosol optical depth retrieval by the Bremen aerosol algorithm. The add-on retrieval of particulate matter uses the derivation of the effective radii from the Ångstroem exponents and an assumed log-normal size distribution function. The Ångstroem exponent is derived through the multi-channel approach using MERIS/Envisat data, and benefits from the fitting of a smooth spectral slope of aerosol optical depth and the surface reflectance. The advantage of the retrieval is that this retrieval of the aerosol mass, i.e., in particular the effective radius, is exclusively based on spectral information from satellite measurements, global aerosol models, and meteorological parameters. ECMWF Boundary layer height, humidity, temperature, and pressure data are used in the retrieval; a retrieval of PM inferred without meteorological information and a proper BRDF is shown to be not very promising. Over the city of Hamburg, the aerosol optical depths agree within a standard deviation of 0.03 and 0.068 for all thirteen wavelengths between 412 and 885 nm, compared with AERONET and ground based air quality measurements; the particulate matter concentrations show agreement with a correlation factor of 0.64. In addition to the urban site of Hamburg, comparisons of PM10 measurements over rural sites in Germany exhibit a correlation coefficient of 0.75.

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Aerosol optical properties in the southeastern United States in summer – Part 2: Sensitivity of aerosol optical depth to relative humidity and aerosol parameters

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-31471-2015 ◽

2015 ◽

Vol 15 (21) ◽

pp. 31471-31499 ◽

Cited By ~ 6

Author(s):

C. A. Brock ◽

N. L. Wagner ◽

B. E. Anderson ◽

A. Beyersdorf ◽

P. Campuzano-Jost ◽

...

Keyword(s):

Refractive Index ◽

Relative Humidity ◽

Aerosol Optical Depth ◽

Optical Depth ◽

Climate Models ◽

Mixed Boundary ◽

Geometric Standard Deviation ◽

Aerosol Mass ◽

Southeastern Us ◽

Aerosol Parameters

Abstract. Aircraft observations of meteorological, trace gas, and aerosol properties were made between May and September 2013. Regionally representative aggregate vertical profiles of median and interdecile ranges of the measured parameters were constructed from 37 individual aircraft profiles made in the afternoon when a well-mixed boundary layer with typical fair-weather cumulus was present (Wagner et al., 2015). We use these 0–4 km aggregate profiles and a simple model to calculate the sensitivity of aerosol optical depth (AOD) to changes in dry aerosol mass, relative humidity, mixed layer height, the central diameter and width of the particle size distribution, hygroscopicity, and dry and wet refractive index, while holding the other parameters constant. The calculated sensitivity is a result of both the intrinsic sensitivity and the observed range of variation of these parameters. These observationally based sensitivity studies indicate that the relationship between AOD and dry aerosol mass in these conditions in the southeastern US can be highly variable and is especially sensitive to relative humidity (RH). For example, calculated AOD ranged from 0.137 to 0.305 as the RH was varied between the 10th and 90th percentile profiles with dry aerosol mass held constant. Calculated AOD was somewhat less sensitive to aerosol hygroscopicity, mean size, and geometric standard deviation, σg. However, some chemistry-climate models prescribe values of σg substantially larger than we or others observe, leading to potential high biases in model-calculated AOD of ~ 25 %. Finally, AOD was least sensitive to observed variations in dry and wet aerosol refractive index and to changes in the height of the well-mixed surface layer. We expect these findings to be applicable to other moderately polluted and background continental airmasses in which an accumulation mode between 0.1–0.5 μm diameter dominates aerosol extinction.

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A low-cost monitor for measurement of fine particulate matter and aerosol optical depth. Part 1: Specifications and testing

10.5194/amt-2019-110 ◽

2019 ◽

Author(s):

Eric A. Wendt ◽

Casey W. Quinn ◽

Daniel D. Miller-Lionberg ◽

Jessica Tryner ◽

Christian L'Orange ◽

...

Keyword(s):

Particulate Matter ◽

Aerosol Optical Depth ◽

Optical Depth ◽

Low Cost ◽

Fine Particulate Matter ◽

Ground Level ◽

Aerosol Mass ◽

Fine Particulate ◽

The Cost ◽

Equivalent Method

Abstract. Globally, fine particulate matter (PM2.5) air pollution is a leading contributor to death, disease, and environmental degradation. Satellite-based measurements of aerosol optical depth (AOD) are used to estimate PM2.5 concentrations across the world, but the relationship between satellite-estimated AOD and ground-level PM2.5 is uncertain. Sun photometers measure AOD from the Earth's surface and are often used to improve satellite data; however, reference-grade photometers and PM2.5 monitors are expensive and rarely co-located. This work presents the development and validation of the Aerosol Mass and Optical Depth (AMOD) sampler, an inexpensive and compact device that simultaneously measures PM2.5 mass and AOD and was designed specifically to be used in citizen science campaigns. The AMOD utilizes a low-cost light-scattering sensor in combination with a gravimetric filter measurement to quantify ground-level PM2.5. Aerosol optical depth is measured using optically filtered photodiodes at four discrete wavelengths. Field validation studies revealed agreement within 10 % for AOD values measured between co-located AMOD and AErosol RObotics NETwork (AERONET) monitors and for PM2.5 mass measured between co-located AMOD and EPA Federal Equivalent Method (FEM) monitors. These results demonstrate that the AMOD can quantify AOD and PM2.5 accurately at a fraction of the cost of existing reference monitors.

Download Full-text