scholarly journals Impact of black carbon aerosol over Italian basin valleys: high resolution measurements along vertical profiles, radiative forcing and heating rate

2014 ◽  
Vol 14 (1) ◽  
pp. 541-591 ◽  
Author(s):  
L. Ferrero ◽  
M. Castelli ◽  
B. S. Ferrini ◽  
M. Moscatelli ◽  
M. G. Perrone ◽  
...  
Keyword(s):  
Black Carbon ◽  
Heating Rate ◽  
Radiative Forcing ◽  
Vertical Profiles ◽  
Mixing Height ◽  
Aerosol Optical Properties ◽  
Height Range ◽  
Aerosol Radiative Forcing ◽  
Black Carbon Aerosol ◽  
Aerosol Radiative

Abstract. This study presents the first measured high resolution vertical profiles of black carbon and calculation of aerosol radiative forcing and atmospheric heating rates in the lower troposphere, over Italy and Europe. The calculation is based on vertical profiles of black carbon, aerosol number size distribution and chemical composition measured over three Italian basin valleys (Po Valley, Terni Valley and Passiria Valley) by means of a tethered balloon equipped with a micro-Aethalometer, an optical particle counter (OPC), a cascade impactor and a meteorological station. Experimental measurements allowed first the calculation of the aerosol optical properties. In this respect, the aerosol refractive index was calculated along height using the effective medium approximation applied to aerosol chemical composition; Mie calculations were performed on the base of the OPC number-size distribution which was corrected for the ambient aerosol refractive index. The obtained vertical profiles of aerosol optical properties were validated with AERONET data and were used as input to the radiative transfer model libRadtran. Vertical profiles of direct aerosol radiative forcing, atmospheric absorption and heating rate were calculated. Reported results evidenced common behaviours along height over the investigated basin valleys (an orographic feature present elsewhere in Europe): at the mixing height a marked a concentration drop of both BC (range: −48.4 ± 5.3% to −69.1 ± 5.5%) and particle number concentration (range: −23.9 ± 4.3% to −46.5 ± 7.3%) was evidenced. More in details, the percentage decrease of BC along height was higher than that measured for aerosol and thus, the BC content of the aerosol decreased along height; correspondingly the Single Scattering Albedo increased along height (range: +4.9 ± 2.2% to +7.4 ± 1.0%). Therefore, the highest atmospheric absorption was observed below the mixing height (range: +0.5 ± 0.1 W m−2 to +2.5 ± 0.2 W m−2) with the associated heating rate characterized by a vertical negative gradient (range: −0.5 K day−1 km−1 to −6.8 K day−1 km−1). As a result, the Black Carbon loaded below the mixing height potentially weakens the ground-based thermal inversions (common over basin valleys) thus promoting an increase of the atmospheric dispersal conditions.

scholarly journals Impact of black carbon aerosol over Italian basin valleys: high-resolution measurements along vertical profiles, radiative forcing and heating rate

2014 ◽  
Vol 14 (18) ◽  
pp. 9641-9664 ◽  
Author(s):  
L. Ferrero ◽  
M. Castelli ◽  
B. S. Ferrini ◽  
M. Moscatelli ◽  
M. G. Perrone ◽  
...  
Keyword(s):  
High Resolution ◽  
Black Carbon ◽  
Heating Rate ◽  
Radiative Forcing ◽  
Transfer Model ◽  
Vertical Profiles ◽  
Radiative Effect ◽  
Mixing Height ◽  
Atmospheric Absorption ◽  
Height Range

Abstract. A systematic study of black carbon (BC) vertical profiles measured at high-resolution over three Italian basin valleys (Terni Valley, Po Valley and Passiria Valley) is presented. BC vertical profiles are scarcely available in literature. The campaign lasted 45 days and resulted in 120 measured vertical profiles. Besides the BC mass concentration, measurements along the vertical profiles also included aerosol size distributions in the optical particle counter range, chemical analysis of filter samples and a full set of meteorological parameters. Using the collected experimental data, we performed calculations of aerosol optical properties along the vertical profiles. The results, validated with AERONET data, were used as inputs to a radiative transfer model (libRadtran). The latter allowed an estimation of vertical profiles of the aerosol direct radiative effect, the atmospheric absorption and the heating rate in the lower troposphere. The present measurements revealed some common behaviors over the studied basin valleys. Specifically, at the mixing height, marked concentration drops of both BC (range: from −48.4 ± 5.3 to −69.1 ± 5.5%) and aerosols (range: from −23.9 ± 4.3 to −46.5 ± 7.3%) were found. The measured percentage decrease of BC was higher than that of aerosols: therefore, the BC aerosol fraction decreased upwards. Correspondingly, both the absorption and scattering coefficients decreased strongly across the mixing layer (range: from −47.6 ± 2.5 to −71.3 ± 3.0% and from −23.5 ± 0.8 to −61.2 ± 3.1%, respectively) resulting in a single-scattering albedo increase along height (range: from +4.9 ± 2.2 to +7.4 ± 1.0%). This behavior influenced the vertical distribution of the aerosol direct radiative effect and of the heating rate. In this respect, the highest atmospheric absorption of radiation was predicted below the mixing height (~ 2–3 times larger than above it) resulting in a heating rate characterized by a vertical negative gradient (range: from −2.6 ± 0.2 to −8.3 ± 1.2 K day−1 km−1). In conclusion, the present results suggest that the BC below the mixing height has the potential to promote a negative feedback on the atmospheric stability over basin valleys, weakening the ground-based thermal inversions and increasing the dispersal conditions.

Aerosol radiative forcing due to enhanced black carbon at an urban site in India

2002 ◽  
Vol 29 (18) ◽  
pp. 27-1-27-4 ◽  
Author(s):  
S. Suresh Babu ◽  
S. K. Satheesh ◽  
K. Krishna Moorthy
Keyword(s):  
Black Carbon ◽  
Radiative Forcing ◽  
Urban Site ◽  
Aerosol Radiative Forcing ◽  
Aerosol Radiative

scholarly journals Sensitivity of aerosol radiative effects to different mixing assumptions in the AEROPT 1.0 submodel of the EMAC atmospheric-chemistry–climate model

2014 ◽  
Vol 7 (5) ◽  
pp. 2503-2516 ◽  
Author(s):  
K. Klingmüller ◽  
B. Steil ◽  
C. Brühl ◽  
H. Tost ◽  
J. Lelieveld
Keyword(s):  
Optical Properties ◽  
Radiative Transfer ◽  
Black Carbon ◽  
Atmospheric Chemistry ◽  
Radiative Forcing ◽  
Climate Model ◽  
Mixing Rule ◽  
Aerosol Optical Properties ◽  
Internal Mixing ◽  
Aerosol Radiative

Abstract. The modelling of aerosol radiative forcing is a major cause of uncertainty in the assessment of global and regional atmospheric energy budgets and climate change. One reason is the strong dependence of the aerosol optical properties on the mixing state of aerosol components, such as absorbing black carbon and, predominantly scattering sulfates. Using a new column version of the aerosol optical properties and radiative-transfer code of the ECHAM/MESSy atmospheric-chemistry–climate model (EMAC), we study the radiative transfer applying various mixing states. The aerosol optics code builds on the AEROPT (AERosol OPTical properties) submodel, which assumes homogeneous internal mixing utilising the volume average refractive index mixing rule. We have extended the submodel to additionally account for external mixing, partial external mixing and multilayered particles. Furthermore, we have implemented the volume average dielectric constant and Maxwell Garnett mixing rule. We performed regional case studies considering columns over China, India and Africa, corroborating much stronger absorption by internal than external mixtures. Well-mixed aerosol is a good approximation for particles with a black-carbon core, whereas particles with black carbon at the surface absorb significantly less. Based on a model simulation for the year 2005, we calculate that the global aerosol direct radiative forcing for homogeneous internal mixing differs from that for external mixing by about 0.5 W m−2.

scholarly journals MACv2-SP: a parameterization of anthropogenic aerosol optical properties and an associated Twomey effect for use in CMIP6

2017 ◽  
Vol 10 (1) ◽  
pp. 433-452 ◽  
Author(s):  
Bjorn Stevens ◽  
Stephanie Fiedler ◽  
Stefan Kinne ◽  
Karsten Peters ◽  
Sebastian Rast ◽  
...  
Keyword(s):  
Optical Properties ◽  
Radiative Forcing ◽  
Industrial Emissions ◽  
Max Planck ◽  
Aerosol Optical Properties ◽  
Anthropogenic Aerosol ◽  
Aerosol Radiative Forcing ◽  
Clear Sky ◽  
Aerosol Forcing ◽  
Aerosol Radiative

Abstract. A simple plume implementation of the second version (v2) of the Max Planck Institute Aerosol Climatology, MACv2-SP, is described. MACv2-SP provides a prescription of anthropogenic aerosol optical properties and an associated Twomey effect. It was created to provide a harmonized description of post-1850 anthropogenic aerosol radiative forcing for climate modeling studies. MACv2-SP has been designed to be easy to implement, change and use, and thereby enable studies exploring the climatic effects of different patterns of aerosol radiative forcing, including a Twomey effect. MACv2-SP is formulated in terms of nine spatial plumes associated with different major anthropogenic source regions. The shape of the plumes is fit to the Max Planck Institute Aerosol Climatology, version 2, whose present-day (2005) distribution is anchored by surface-based observations. Two types of plumes are considered: one predominantly associated with biomass burning, the other with industrial emissions. These differ in the prescription of their annual cycle and in their optical properties, thereby implicitly accounting for different contributions of absorbing aerosol to the different plumes. A Twomey effect for each plume is prescribed as a change in the host model's background cloud-droplet population density using relationships derived from satellite data. Year-to-year variations in the amplitude of the plumes over the historical period (1850–2016) are derived by scaling the plumes with associated national emission sources of SO2 and NH3. Experiments using MACv2-SP are performed with the Max Planck Institute Earth System Model. The globally and annually averaged instantaneous and effective aerosol radiative forcings are estimated to be −0.6 and −0.5 W m−2, respectively. Forcing from aerosol–cloud interactions (the Twomey effect) offsets the reduction of clear-sky forcing by clouds, so that the net effect of clouds on the aerosol forcing is small; hence, the clear-sky forcing, which is more readily measurable, provides a good estimate of the total aerosol forcing.

scholarly journals Role of black carbon mass size distribution in the direct aerosol radiative forcing

2019 ◽  
Vol 19 (20) ◽  
pp. 13175-13188 ◽  
Author(s):  
Gang Zhao ◽  
Jiangchuan Tao ◽  
Ye Kuang ◽  
Chuanyang Shen ◽  
Yingli Yu ◽  
...  
Keyword(s):  
Size Distribution ◽  
Black Carbon ◽  
Radiative Forcing ◽  
Climate Models ◽  
Radiative Effects ◽  
Aerosol Radiative Forcing ◽  
Mass Size Distribution ◽  
Mass Size ◽  
Mixing States ◽  
Aerosol Radiative

Abstract. Large uncertainties exist when estimating radiative effects of ambient black carbon (BC) aerosol. Previous studies about the BC aerosol radiative forcing mainly focus on the BC aerosols' mass concentrations and mixing states, while the effects of BC mass size distribution (BCMSD) were not well considered. In this paper, we developed a method of measuring the BCMSD by using a differential mobility analyzer in tandem with an Aethalometer. A comprehensive method of multiple charging corrections was proposed and implemented in measuring the BCMSD. Good agreement was obtained between the BC mass concentration integrated from this system and that measured in the bulk phase, demonstrating the reliability of our proposed method. Characteristics of the BCMSD and corresponding radiative effects were studied based on a field measurement campaign conducted in the North China Plain by using our own measurement system. Results showed that the BCMSD had two modes and the mean peak diameters of the modes were 150 and 503 nm. The BCMSD of the coarser mode varied significantly under different pollution conditions with peak diameter varying between 430 and 580 nm, which gave rise to significant variation in aerosol bulk optical properties. The direct aerosol radiative forcing was estimated to vary by 8.45 % for different measured BCMSDs of the coarser mode, which shared the same magnitude with the variation associated with assuming different aerosol mixing states (10.5 %). Our study reveals that the BCMSD as well as its mixing state in estimating the direct aerosol radiative forcing matters. Knowledge of the BCMSD should be fully considered in climate models.

scholarly journals Wet removal of black carbon in Asian outflow: Aerosol Radiative Forcing in East Asia (A-FORCE) aircraft campaign

2012 ◽  
Vol 117 (D3) ◽  
pp. n/a-n/a ◽  
Author(s):  
N. Oshima ◽  
Y. Kondo ◽  
N. Moteki ◽  
N. Takegawa ◽  
M. Koike ◽  
...  
Keyword(s):  
East Asia ◽  
Black Carbon ◽  
Radiative Forcing ◽  
Aerosol Radiative Forcing ◽  
Aerosol Radiative ◽  
Wet Removal

Constraining direct aerosol radiative forcing using remote sensing and in-situ constraints

2020 ◽  
Author(s):  
Lucia Timea Deaconu ◽  
Duncan Watson-Parris ◽  
Philip Stier ◽  
Lindsay Lee
Keyword(s):  
Remote Sensing ◽  
Black Carbon ◽  
Optical Depth ◽  
Radiative Forcing ◽  
Removal Rates ◽  
Aerosol Radiative Forcing ◽  
Aerosol Absorption ◽  
Direct Radiative Forcing ◽  
Aerosol Radiative

<p>Absorbing aerosols affect the climate system (radiative forcing, cloud formation, precipitation and more) by strongly absorbing solar radiation, particularly at ultraviolet and visible wavelengths. The environmental impacts of an absorbing aerosol layer are influenced by its single scattering albedo (SSA), the albedo of the underlying surface, and also by the atmospheric residence time and column concentration of the aerosols.</p><p>Black-carbon (BC), the collective term used for strongly absorbing, carbonaceous aerosols, emitted by incomplete combustion of fossil fuel, biofuel and biomass, is a significant contributor to atmospheric absorption and probably a main-driver in inter-model differences and large uncertainties in estimating the aerosol radiative forcing due to aerosol-radiation interaction (RFari). Estimates of BC direct radiative forcing suggest a positive effect of +0.71 Wm<sup>-2</sup> (Bond and Bergstrom (2006)) with large uncertainties [+0.08, +1.27] Wm<sup>-2</sup>. These uncertainties result from poor estimates of BC atmospheric burden (emissions and removal rates) and its radiative properties. The uncertainty in the burden is due to the uncertainty in emissions (7.5 [2, 29] Tg yr<sup>-1</sup>) and lifetime (removal rates). In comparison with the available observations, global climate models (GCMs) tend to under-predict absorption near source (e.g. at AERONET stations), and over-predict concentrations in remote regions (e.g. as measured by aircraft campaigns). This may be due to GCM’s weak emissions at the source, but longer lifetime of aerosols in the atmosphere.</p><p>This study aims to address the parametric uncertainty of GCMs and constrain the direct radiative forcing using a perturbed parameter ensemble (PPE) and a collection of observations, from remote sensing to in-situ measurements. Total atmospheric aerosol extinction is quantified using satellite observations that provide aerosol optical depth (AOD), while the SSA is constrained by the use of high-temporal resolution aerosol absorption optical depth (AAOD) measured with AERONET sun-photometers (for near-source columnar information of aerosol absorption) and airborne black-carbon in-situ measurements collected and synthesised in the Global Aerosol Synthesis and Science Project (GASSP) (for properties of long-range transported aerosols). Measurements from the airborne campaigns ATOM and HIPPO are valuable for constraining aerosol absorption in remote areas, while CLARIFY and ORACLES, that were employed over Southeast Atlantic, are considered in our study for near source observations of biomass burning aerosols transported over the bright surface of stratocumulus clouds.</p><p>Using the PPE to explore the uncertainties in the aerosol absorption as well as the dominant emission and removal processes, and by comparing with a variety of observations we have confidence to better constrain the aerosol direct radiative forcing.</p>

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