scholarly journals Estimation of mineral dust longwave radiative forcing: sensitivity study to particle properties and application to real cases over Barcelona

2014 ◽  
Vol 14 (6) ◽  
pp. 8533-8573 ◽  
Author(s):  
M. Sicard ◽  
S. Bertolín ◽  
M. Mallet ◽  
P. Dubuisson ◽  
A. Comerón
Keyword(s):  
Spectral Range ◽  
Radiative Forcing ◽  
Mineral Dust ◽  
Opposite Sign ◽  
Sensitivity Study ◽  
Global Scale ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Radiative Effect ◽  
Aerosol Forcing

Abstract. The aerosol radiative effect in the longwave (LW) spectral range is sometimes not taken into account in atmospheric aerosol forcing studies at local scale because the LW aerosol effect is assumed to be negligible. At regional and global scale this effect is partially taken into account: aerosol absorption is taken into account but scattering is still neglected. However, aerosols with strong absorbing and scattering properties in the LW region, like mineral dust, can have a non-negligible radiative effect in the LW spectral range (both at surface and top of the atmosphere) which can counteract their cooling effect occurring in the shortwave spectral range. The first objective of this research is to perform a sensitivity study of mineral dust LW radiative forcing (RF) as a function of dust microphysical and optical properties using an accurate radiative transfer model which can compute vertically-resolved shortwave and longwave aerosol RF. Radiative forcing simulations in the LW range have shown an important sensitivity to the following parameters: aerosol load, radius of the coarse mode, refractive index, aerosol vertical distribution, surface temperature and surface albedo. The scattering effect has been estimated to contribute to the LW RF up to 18% at the surface and up to 38% at the top of the atmosphere. The second objective is the estimation of the shortwave and longwave dust RF for 11 dust outbreaks observed in Barcelona. At the surface, the LW RF varies between +2.8 and +10.2 W m−2, which represents between 11 and 26% (with opposite sign) of the SW component, while at the top of the atmosphere the LW RF varies between +0.6 and +5.8 W m−2, which represents between 6 and 26% (with opposite sign) of the SW component.

scholarly journals Estimation of mineral dust long-wave radiative forcing: sensitivity study to particle properties and application to real cases in the region of Barcelona

2014 ◽  
Vol 14 (17) ◽  
pp. 9213-9231 ◽  
Author(s):  
M. Sicard ◽  
S. Bertolín ◽  
M. Mallet ◽  
P. Dubuisson ◽  
A. Comerón
Keyword(s):  
Spectral Range ◽  
Radiative Forcing ◽  
Mineral Dust ◽  
Opposite Sign ◽  
Sensitivity Study ◽  
Short Wave ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Radiative Effect ◽  
Long Wave

Abstract. The aerosol radiative effect in the long-wave (LW) spectral range is sometimes not taken into account in atmospheric aerosol forcing studies at local scale because the LW aerosol effect is assumed to be negligible. At regional and global scale this effect is partially taken into account: aerosol absorption is taken into account but scattering is still neglected. However, aerosols with strong absorbing and scattering properties in the LW region, like mineral dust, can have a non-negligible radiative effect in the LW spectral range (both at surface and top of the atmosphere) which can counteract their cooling effect occurring in the short-wave spectral range. The first objective of this research is to perform a sensitivity study of mineral dust LW radiative forcing (RF) as a function of dust microphysical and optical properties using an accurate radiative transfer model which can compute vertically resolved short-wave and long-wave aerosol RF. Radiative forcing simulations in the LW range have shown an important sensitivity to the following parameters: aerosol load, radius of the coarse mode, refractive index, aerosol vertical distribution, surface temperature and surface albedo. The scattering effect has been estimated to contribute to the LW RF up to 18% at the surface and up to 38% at the top of the atmosphere. The second objective is the estimation of the short-wave and long-wave dust RF for 11 dust outbreaks observed in Barcelona. At the surface, the LW RF varies between +2.8 and +10.2 W m−2, which represents between 11 and 26% (with opposite sign) of the SW component, while at the top of the atmosphere the LW RF varies between +0.6 and +5.8 W m−2, which represents between 6 and 26% (with opposite sign) of the SW component.

Radiative forcing over the Arctic of aerosols from the August 2017 Canadian and Greenlandic wildfires

2021 ◽  
Author(s):  
Filippo Calì Quaglia ◽  
Daniela Meloni ◽  
Alcide Giorgio di Sarra ◽  
Tatiana Di Iorio ◽  
Virginia Ciardini ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Radiative Forcing ◽  
Solar Zenith Angle ◽  
Surface Albedo ◽  
High Arctic ◽  
The Arctic ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Aerosol Layer ◽  
Radiative Effect

<p>Extended and intense wildfires occurred in Northern Canada and, unexpectedly, on the Greenlandic West coast during summer 2017. The thick smoke plume emitted into the atmosphere was transported to the high Arctic, producing one of the largest impacts ever observed in the region. Evidence of Canadian and Greenlandic wildfires was recorded at the Thule High Arctic Atmospheric Observatory (THAAO, 76.5°N, 68.8°W, www.thuleatmos-it.it) by a suite of instruments managed by ENEA, INGV, Univ. of Florence, and NCAR. Ground-based observations of the radiation budget have allowed quantification of the surface radiative forcing at THAAO. </p><p>Excess biomass burning chemical tracers such as CO, HCN, H2CO, C2H6, and NH3 were  measured in the air column above Thule starting from August 19 until August 23. The aerosol optical depth (AOD) reached a peak value of about 0.9 on August 21, while an enhancement of wildfire compounds was  detected in PM10. The measured shortwave radiative forcing was -36.7 W/m2 at 78° solar zenith angle (SZA) for AOD=0.626.</p><p>MODTRAN6.0 radiative transfer model (Berk et al., 2014) was used to estimate the aerosol radiative effect and the heating rate profiles at 78° SZA. Measured temperature profiles, integrated water vapour, surface albedo, spectral AOD and aerosol extinction profiles from CALIOP onboard CALIPSO were used as model input. The peak  aerosol heating rate (+0.5 K/day) was  reached within the aerosol layer between 8 and 12 km, while the maximum radiative effect (-45.4 W/m2) is found at 3 km, below the largest aerosol layer.</p><p>The regional impact of the event that occurred on August 21 was investigated using a combination of atmospheric radiative transfer modelling with measurements of AOD and ground surface albedo from MODIS. The aerosol properties used in the radiative transfer model were constrained by in situ measurements from THAAO. Albedo data over the ocean have been obtained from Jin et al. (2004). Backward trajectories produced through HYSPLIT simulations (Stein et al., 2015) were also employed to trace biomass burning plumes.</p><p>The radiative forcing efficiency (RFE) over land and ocean was derived, finding values spanning from -3 W/m2 to -132 W/m2, depending on surface albedo and solar zenith angle. The fire plume covered a vast portion of the Arctic, with large values of the daily shortwave RF (< -50 W/m2) lasting for a few days. This large amount of aerosol is expected to influence cloud properties in the Arctic, producing significant indirect radiative effects.</p>

scholarly journals Contrasting the direct radiative effect and direct radiative forcing of aerosols

2014 ◽  
Vol 14 (11) ◽  
pp. 5513-5527 ◽  
Author(s):  
C. L. Heald ◽  
D. A. Ridley ◽  
J. H. Kroll ◽  
S. R. H. Barrett ◽  
K. E. Cady-Pereira ◽  
...  
Keyword(s):  
Energy Balance ◽  
Radiative Forcing ◽  
Transport Model ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Radiative Effect ◽  
Chemical Transport Model ◽  
Anthropogenic Aerosols ◽  
Anthropogenic Aerosol ◽  
Direct Radiative Forcing

Abstract. The direct radiative effect (DRE) of aerosols, which is the instantaneous radiative impact of all atmospheric particles on the Earth's energy balance, is sometimes confused with the direct radiative forcing (DRF), which is the change in DRE from pre-industrial to present-day (not including climate feedbacks). In this study we couple a global chemical transport model (GEOS-Chem) with a radiative transfer model (RRTMG) to contrast these concepts. We estimate a global mean all-sky aerosol DRF of −0.36 Wm−2 and a DRE of −1.83 Wm−2 for 2010. Therefore, natural sources of aerosol (here including fire) affect the global energy balance over four times more than do present-day anthropogenic aerosols. If global anthropogenic emissions of aerosols and their precursors continue to decline as projected in recent scenarios due to effective pollution emission controls, the DRF will shrink (−0.22 Wm−2 for 2100). Secondary metrics, like DRE, that quantify temporal changes in both natural and anthropogenic aerosol burdens are therefore needed to quantify the total effect of aerosols on climate.

scholarly journals Contrasting Mineral Dust Abundances from X-Ray Diffraction and Reflectance Spectroscopy

2021 ◽  
Author(s):  
Mohammad R. Sadrian ◽  
Wendy M. Calvin ◽  
John McCormack
Keyword(s):  
Radiative Forcing ◽  
Mineral Dust ◽  
Reflectance Spectroscopy ◽  
Urban Setting ◽  
Dust Particles ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
X Ray Diffraction ◽  
Atmospheric Dust ◽  
X Ray

Abstract. Mineral dust particles dominate aerosol mass in the atmosphere and directly modify Earth’s radiative balance through absorption and scattering. This radiative forcing varies strongly with mineral composition, yet there is still limited knowledge on the mineralogy of atmospheric dust. In this study, we performed X-ray diffraction (XRD) and reflectance spectroscopy measurements on 37 different atmospheric dust samples collected as airfall in an urban setting to determine mineralogy and the relative proportions of minerals in the dust mixture. Most commonly, XRD has been used to characterize dust mineralogy; however, without prior special sample preparation, this technique is less effective for identifying poorly crystalline or amorphous phases. In addition to XRD measurements, we performed visible, near-infrared, and short-wave infrared (VNIR/SWIR) reflectance spectroscopy for these natural dust samples as a complementary technique to determine minerology and mineral abundances. Reflectance spectra of dust particles are a function of a nonlinear combination of mineral abundances in the mixture. Therefore, we used a Hapke radiative transfer model along with a linear spectral mixing approach to derive relative mineral abundances from reflectance spectroscopy. We compared spectrally derived abundances with those determined semi-quantitatively from XRD. Our results demonstrate that total clay mineral abundances from XRD are correlated with those from reflectance spectroscopy and follow similar trends; however, XRD underpredicts the total amount of clay for many of the samples. On the other hand, calcite abundances are significantly underpredicted by SWIR compared to XRD. This is caused by the weakening of absorption features associated with the fine particle size of the samples, as well as the presence of dark non-mineral materials (e.g., asphalt) in these samples. Another possible explanation for abundance discrepancies between XRD and SWIR is related to the differing sensitivity of the two techniques (crystal structure vs chemical bonds). Our results indicate that it is beneficial to use both XRD and reflectance spectroscopy to characterize airfall dust, because the former technique is good at identifying and quantifying the SWIR-transparent minerals (e.g., quartz, albite, and microcline), while the latter technique is superior for determining abundances for clays and non-mineral components.

scholarly journals Anthropogenic aerosol forcing under the Shared Socioeconomic Pathways

2019 ◽  
Author(s):  
Marianne T. Lund ◽  
Gunnar Myhre ◽  
Bjørn H. Samset
Keyword(s):  
Air Pollution ◽  
Radiative Forcing ◽  
Global Climate ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Air Pollution Control ◽  
Anthropogenic Aerosols ◽  
Anthropogenic Aerosol ◽  
Aerosol Radiative Forcing ◽  
Aerosol Forcing

Abstract. Emissions of anthropogenic aerosols are expected to change drastically over the coming decades, with potentially significant climate implications. Using the most recent generation of harmonized emission scenarios, the Shared Socioeconomic Pathways (SSPs) as input to a global chemistry transport and radiative transfer model, we provide estimates of the projected future global and regional burdens and radiative forcing of anthropogenic aerosols under three different levels of air pollution control: strong (SSP1), medium (SSP2) and weak (SSP3). We find that the broader range of future air pollution emission trajectories spanned by the SSPs compared to previous scenarios translates into total aerosol forcing estimates in 2100 relative to 1750 ranging from −0.04 W m−2 in SSP1-1.9 to −0.51 W m−2 in SSP3-7.0. Compared to our 1750–2015 estimate of −0.61 W m−2, this shows that depending on the success of air pollution policies over the coming decades, aerosol radiative forcing may weaken by nearly 95 % or remain close to the pre-industrial to present-day level. In all three scenarios there is a positive forcing in 2100 relative to 2015, from 0.51 W m−2 in SSP1-1.9 to 0.04 W m−2 in SSP3-7.0. Results also demonstrate significant differences across regions and scenarios, especially in South Asia and Africa. While rapid weakening of the negative aerosol forcing following effective air quality policies will unmask more of the greenhouse gas-induced global warming, slow progress on mitigating air pollution will significantly enhance the atmospheric aerosol levels and risk to human health. In either case, the resulting impacts on regional and global climate can be significant.

scholarly journals 2-D mineral dust radiative forcing calculations from CALIPSO observations over Europe

2019 ◽  
Author(s):  
Maria José Granados-Muñoz ◽  
Michaël Sicard ◽  
Nikolaos Papagiannopoulos ◽  
Rubén Barragán ◽  
Juan Antonio Bravo-Aranda ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Mineral Dust ◽  
Single Point ◽  
Strong Dependence ◽  
Radiant Energy ◽  
Radiative Properties ◽  
Radiative Transfer Model ◽  
Orthogonal Polarization ◽  
Transfer Model ◽  
Radiative Effects

Abstract. A demonstration study to examine the feasibility to retrieve dust radiative effects based on combined satellite data from MODIS (Moderate Resolution Imaging Spectroradiometer), CERES (Clouds and the Earth’s Radiant Energy System) and CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) li-dar vertical profiles along their orbit is presented. The radiative transfer model GAME (Global Atmos-pheric Model) is used to estimate the shortwave and longwave dust radiative effects below the CALIP-SO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite) orbit assuming an aerosol parameterization based on CALIOP vertical distribution at a horizontal resolution of 5 km and additional AERONET (Aerosol Robotic Network) data. Two study cases are analysed; a strong long-range transport mineral dust event (AOD = 0.52) originated in the Sahara Desert and reaching the United Kingdom and a weaker event (AOD = 0.16) affecting Eastern Europe. The obtained radiative fluxes are first validated in terms of radiative forcing efficiency at a single point with space-time co-located lidar ground-based measurements from EARLINET (European Aerosol Research Lidar Network) stations below the orbit. The methodology is then applied to the full orbit. The obtained results indicate that the radiative effects show a strong dependence on the aerosol load, highlighting the need of accurate AOD measurements for forcing studies, and on the surface albedo. The calculated dust radiative effects and heating rates below the orbits are in good agreement with previous studies of mineral dust, with the forcing efficiency obtained at the surface ranging between −80.3 and −63.0 W m−2 for the weaker event and −119.1 and −79.3 W m−2 for the strong one. Results thus demonstrate the validity of the presented method to retrieve 2-D accurate radiative properties with large spatial and temporal coverage.

Effects of Three-Dimensional Photon Transport on the Radiative Forcing of Realistic Contrails

2012 ◽  
Vol 69 (7) ◽  
pp. 2243-2255 ◽  
Author(s):  
Linda Forster ◽  
Claudia Emde ◽  
Bernhard Mayer ◽  
Simon Unterstrasser
Keyword(s):  
Radiative Forcing ◽  
Climate Models ◽  
Three Dimensional ◽  
Vertical Wind Shear ◽  
Global Scale ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Monte Carlo Code ◽  
3D Effects ◽  
3D Effect

Abstract Estimates of the global radiative forcing (RF) of line-shaped contrails and contrail cirrus exhibit a high level of uncertainty. In most cases, 1D radiative models have been used to determine the RF on a global scale. In this paper the effect of neglecting the 3D radiative effects of realistic contrails is quantified. Calculating the 3D effects of an idealized elliptical contrail as in the work of Gounou and Hogan with the 3D radiative transfer model MYSTIC (for “Monte Carlo code for the physically correct tracing of photons in cloudy atmospheres”) produced comparable results: as in Gounou and Hogan’s work the 3D effect (i.e., the difference in RF between a 3D calculation and a 1D approximation) on contrail RF was on the order of 10% in the longwave and shortwave. The net 3D effect, however, can be much larger, since the shortwave and longwave RF largely cancel during the day. For the investigation of the 3D effects of more realistic contrails, the microphysical input was provided by simulations of a 2D contrail-to-cirrus large-eddy simulation (LES) model. To capture some of the real variability in contrail properties, this paper examines two contrail evolutions from 20 min up to 6 h in an environment with either high or no vertical wind shear. This study reveals that the 3D effects show a high variability under realistic conditions since they depend strongly on the optical properties and the evolutionary state of the contrails. The differences are especially large for low elevations of the sun and contrails spreading in a sheared environment. Thus, a parameterization of the 3D effects in climate models would need to consider both geometry and microphysics of the contrail.

scholarly journals The direct and indirect radiative effects of biogenic secondary organic aerosol

2013 ◽  
Vol 13 (6) ◽  
pp. 16961-17019 ◽  
Author(s):  
C. E. Scott ◽  
A. Rap ◽  
D. V. Spracklen ◽  
P. M. Forster ◽  
K. S. Carslaw ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Radiative Transfer Model ◽  
Anthropogenic Emissions ◽  
Transfer Model ◽  
Particle Nucleation ◽  
Radiative Effect ◽  
Radiative Impact ◽  
Global Mean

Abstract. We use a global aerosol microphysics model in combination with an offline radiative transfer model to quantify the radiative effect of biogenic secondary organic aerosol (SOA) in the present day atmosphere. Through its role in particle growth and ageing, the presence of biogenic SOA increases the global annual mean concentration of cloud condensation nuclei (CCN; at 0.2% supersaturation) by 3.6–21.1%, depending upon the yield of SOA production, and the nature and treatment of concurrent primary carbonaceous emissions. This increase in CCN causes a rise in global annual mean cloud droplet number concentration (CDNC) of 1.9–5.2%, and a global mean first aerosol indirect effect (AIE) of between +0.01 W m−2 and −0.12 W m−2. The radiative impact of biogenic SOA is far greater when it also contributes to particle nucleation; using two organically-mediated mechanisms for new particle formation we simulate global annual mean AIEs of −0.22 W m−2 and −0.77 W m−2. The inclusion of biogenic SOA substantially improves the simulated seasonal cycle in the concentration of CCN sized particles observed at three forested sites. The best correlation is found when the organically-mediated nucleation mechanisms are applied, suggesting that the AIE of biogenic SOA could be as large as −0.77 W m−2. The radiative impact of SOA is sensitive to the presence of anthropogenic emissions. Lower background aerosol concentrations simulated with anthropogenic emissions from 1750 give rise to a greater fractional CCN increase and a more substantial indirect radiative effect from biogenic SOA. Consequently, the anthropogenic indirect radiative forcing between 1750 and the present day is sensitive to assumptions about the amount and role of biogenic SOA. We also calculate an annual global mean direct radiative effect (DRE) of between −0.08 W m−2 and −0.78 W m−2 in the present day, with uncertainty in the amount of SOA produced from the oxidation of biogenic volatile organic compounds (BVOCs) accounting for most of this range.

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