scholarly journals Measurement report: Quantifying source contribution and radiative forcing of fossil fuel and biomass burning black carbon aerosol in the southeastern margin of Tibetan Plateau

2020 ◽  
Author(s):  
Huikun Liu ◽  
Qiyuan Wang ◽  
Li Xing ◽  
Yong Zhang ◽  
Ting Zhang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Black Carbon ◽  
Biomass Burning ◽  
Radiative Forcing ◽  
Fossil Fuel ◽  
Sampling Site ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Southeastern Margin ◽  
Fuel Source

Abstract. Black carbon (BC) aerosol plays a vital role in disturbing the balance of ecosystem and climate stability of Tibetan Plateau (TP). An intensive campaign was carried out from 14th March to 12th May 2018 in the southeastern margin of TP to investigate the sources of BC and their radiative effects. To do so, an improved aethalometer model was used to distinguish and apportion BC into fossil fuel combustion source and biomass burning source. To minimize the uncertainty associated with the aethalometer model, a receptor model coupling multi-wavelength absorption with chemical species was used to retrieve the site-dependent Ångström exponent (AAE) and BC mass absorption cross-section (MAC). The results show that the AAEs and BC MACs at wavelength of 880 nm were 0.9 and 12.3 m2 g−1 for fossil fuel source and 1.7 and 10.4 m2 g−1 for biomass burning, respectively. Based on these parameters, the fossil fuel source-related BC (BCfossil) was estimated 43 % of the total BC and the rest 57 % was from biomass burning (BCbiomass) during the campaign. The results from a regional chemical dynamical model reveal that high BCbiomass was contributed from the northeastern India and northern Burma, and the Southeast Asia can explain 40 % of BCbiomass. The high BCfossil was mainly identified from the southeast of sampling site. A radiative transfer model estimated that the atmospheric directive radiative forcing of BC was +4.6 ± 2.4 W m−2 on average, including +2.5 ± 1.8 W m−2 from BCbiomass, and +2.1 ± 0.9 W m−2 from BCfossil, which correspond to and heating rates of 0.07 ± 0.05 and 0.06 ± 0.02 K day−1, respectively. Our study will be useful for improving our understanding in BC sources on the TP and their climatic effect.

scholarly journals Measurement report: quantifying source contribution of fossil fuels and biomass-burning black carbon aerosol in the southeastern margin of the Tibetan Plateau

2021 ◽  
Vol 21 (2) ◽  
pp. 973-987
Author(s):  
Huikun Liu ◽  
Qiyuan Wang ◽  
Li Xing ◽  
Yong Zhang ◽  
Ting Zhang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Southeast Asia ◽  
Black Carbon ◽  
Biomass Burning ◽  
Fossil Fuels ◽  
Anthropogenic Sources ◽  
Transfer Model ◽  
Transport Channel ◽  
Source Contribution ◽  
Southeastern Margin

Abstract. Anthropogenic emissions of black carbon (BC) aerosol are transported from Southeast Asia to the southwestern Tibetan Plateau (TP) during the pre-monsoon; however, the quantities of BC from different anthropogenic sources and the transport mechanisms are still not well constrained because there have been no high-time-resolution BC source apportionments. Intensive measurements were taken in a transport channel for pollutants from Southeast Asia to the southeastern margin of the TP during the pre-monsoon to investigate the influences of fossil fuels and biomass burning on BC. A receptor model that coupled multi-wavelength absorption with aerosol species concentrations was used to retrieve site-specific Ångström exponents (AAEs) and mass absorption cross sections (MACs) for BC. An “aethalometer model” that used those values showed that biomass burning had a larger contribution to BC mass than fossil fuels (BCbiomass=57 % versus BCfossil=43 %). The potential source contribution function indicated that BCbiomass was transported to the site from northeastern India and northern Burma. The Weather Research and Forecasting model coupled with chemistry (WRF-Chem) indicated that 40 % of BCbiomass originated from Southeast Asia, while the high BCfossil was transported from the southwest of the sampling site. A radiative transfer model indicated that the average atmospheric direct radiative effect (DRE) of BC was +4.6 ± 2.4 W m−2, with +2.5 ± 1.8 W m−2 from BCbiomass and +2.1 ± 0.9 W m−2 from BCfossil. The DRE of BCbiomass and BCfossil produced heating rates of 0.07 ± 0.05 and 0.06 ± 0.02 K d−1, respectively. This study provides insights into sources of BC over a transport channel to the southeastern TP and the influence of the cross-border transportation of biomass-burning emissions from Southeast Asia during the pre-monsoon.

scholarly journals Brown carbon aerosol in the North American continental troposphere: sources, abundance, and radiative forcing

2015 ◽  
Vol 15 (14) ◽  
pp. 7841-7858 ◽  
Author(s):  
J. Liu ◽  
E. Scheuer ◽  
J. Dibb ◽  
G. S. Diskin ◽  
L. D. Ziemba ◽  
...  
Keyword(s):  
Biomass Burning ◽  
North American ◽  
Radiative Forcing ◽  
Single Scattering ◽  
Measurement Range ◽  
Radiative Transfer Model ◽  
Chemical Components ◽  
Transfer Model ◽  
Brown Carbon ◽  
The North

Abstract. Chemical components of organic aerosol (OA) selectively absorb light at short wavelengths. In this study, the prevalence, sources, and optical importance of this so-called brown carbon (BrC) aerosol component are investigated throughout the North American continental tropospheric column during a summer of extensive biomass burning. Spectrophotometric absorption measurements on extracts of bulk aerosol samples collected from an aircraft over the central USA were analyzed to directly quantify BrC abundance. BrC was found to be prevalent throughout the 1 to 12 km altitude measurement range, with dramatic enhancements in biomass-burning plumes. BrC to black carbon (BC) ratios, under background tropospheric conditions, increased with altitude, consistent with a corresponding increase in the absorption Ångström exponent (AAE) determined from a three-wavelength particle soot absorption photometer (PSAP). The sum of inferred BC absorption and measured BrC absorption at 365 nm was within 3 % of the measured PSAP absorption for background conditions and 22 % for biomass burning. A radiative transfer model showed that BrC absorption reduced top-of-atmosphere (TOA) aerosol forcing by ~ 20 % in the background troposphere. Extensive radiative model simulations applying this study background tropospheric conditions provided a look-up chart for determining radiative forcing efficiencies of BrC as a function of a surface-measured BrC : BC ratio and single scattering albedo (SSA). The chart is a first attempt to provide a tool for better assessment of brown carbon's forcing effect when one is limited to only surface data. These results indicate that BrC is an important contributor to direct aerosol radiative forcing.

scholarly journals Interpreting the Ultraviolet Aerosol Index observed with the OMI satellite instrument to understand absorption by organic aerosols: implications for atmospheric oxidation and direct radiative effects

2015 ◽  
Vol 15 (19) ◽  
pp. 27405-27447
Author(s):  
M. S. Hammer ◽  
R. V. Martin ◽  
A. van Donkelaar ◽  
V. Buchard ◽  
O. Torres ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
South America ◽  
Biomass Burning ◽  
Southern Africa ◽  
Radiative Forcing ◽  
Transport Model ◽  
Organic Aerosol ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Aerosol Index

Abstract. Satellite observations of the Ultraviolet Aerosol Index (UVAI) are sensitive to absorption of solar radiation by aerosols; this absorption affects photolysis frequencies and radiative forcing. We develop a global simulation of the UVAI using the 3-D chemical transport model GEOS-Chem coupled with the Vector Linearized Discrete Ordinate Radiative Transfer model (VLIDORT). The simulation is applied to interpret UVAI observations from the Ozone Monitoring Instrument (OMI) for the year 2007. Simulated and observed values are highly consistent in regions where mineral dust dominates the UVAI, but a large negative bias (−0.32 to −0.97) exists between simulated and observed values in biomass burning regions. We determine effective optical properties for absorbing organic aerosol, known as brown carbon (BrC), and implement them into GEOS-Chem to better represent observed UVAI values over biomass burning regions. The addition of absorbing BrC decreases the mean bias between simulated and OMI UVAI values from −0.57 to −0.09 over West Africa in January, from −0.32 to +0.0002 over South Asia in April, from −0.97 to −0.22 over southern Africa in July, and from −0.50 to +0.33 over South America in September. The spectral dependence of absorption after adding BrC to the model is broadly consistent with reported observations for biomass burning aerosol, with Absorbing Angstrom Exponent (AAE) values ranging from 2.9 in the ultraviolet (UV) to 1.3 across the UV-Near IR spectrum. We assess the effect of the additional UV absorption by BrC on atmospheric photochemistry by examining tropospheric hydroxyl radical (OH) concentrations in GEOS-Chem. The inclusion of BrC decreases OH by up to 35 % over South America in September, up to 25 % over southern Africa in July, and up to 20 % over other biomass burning regions. Global annual mean OH concentrations in GEOS-Chem decrease due to the presence of absorbing BrC, increasing the methyl chloroform lifetime from 5.62 to 5.68 years, thus reducing the bias against observed values. We calculate the direct radiative effect (DRE) of BrC using GEOS-Chem coupled with the radiative transfer model RRTMG (GC-RT). Treating organic aerosol as containing absorbing BrC rather than as primarily scattering changes global annual mean all-sky top of atmosphere (TOA) DRE by +0.05 W m-2 and all-sky surface DRE by −0.06 W m-2. Regional changes of up to +0.5 W m-2 at TOA and down to −1 W m-2 at the surface are found over major biomass burning regions.

Estimation of Surface and Top-of-Atmosphere Shortwave Irradiance in Biomass-Burning Regions during SCAR-B

2000 ◽  
Vol 39 (10) ◽  
pp. 1742-1753 ◽  
Author(s):  
Sundar A. Christopher ◽  
Xiang Li ◽  
Ronald M. Welch ◽  
Jeffrey S. Reid ◽  
Peter V. Hobbs ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Biomass Burning ◽  
Optical Thickness ◽  
Radiative Forcing ◽  
Wavelength Dependence ◽  
Single Scattering ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Aerosol Radiative Forcing ◽  
Mean Square Errors

Abstract Using in situ measurements of aerosol optical properties and ground-based measurements of aerosol optical thickness (τs) during the Smoke, Clouds and Radiation—Brazil (SCAR-B) experiment, a four-stream broadband radiative transfer model is used to estimate the downward shortwave irradiance (DSWI) and top-of-atmosphere (TOA) shortwave aerosol radiative forcing (SWARF) in cloud-free regions dominated by smoke from biomass burning in Brazil. The calculated DSWI values are compared with broadband pyranometer measurements made at the surface. The results show that, for two days when near-coincident measurements of single-scattering albedo ω0 and τs are available, the root-mean-square errors between the measured and calculated DSWI for daytime data are within 30 W m−2. For five days during SCAR-B, however, when assumptions about ω0 have to be made and also when τs was significantly higher, the differences can be as large as 100 W m−2. At TOA, the SWARF per unit optical thickness ranges from −20 to −60 W m−2 over four major ecosystems in South America. The results show that τs and ω0 are the two most important parameters that affect DSWI calculations. For SWARF values, surface albedos also play an important role. It is shown that ω0 must be known within 0.05 and τs at 0.55 μm must be known to within 0.1 to estimate DSWI to within 20 W m−2. The methodology described in this paper could serve as a potential strategy for determining DSWI values in the presence of aerosols. The wavelength dependence of τs and ω0 over the entire shortwave spectrum is needed to improve radiative transfer calculations. If global retrievals of DSWI and SWARF from satellite measurements are to be performed in the presence of biomass-burning aerosols on a routine basis, a concerted effort should be made to develop methodologies for estimating ω0 and τs from satellite and ground-based measurements.

scholarly journals Black Carbon Aerosol Characteristics and Its Radiative Impact over Nainital: A High-Altitude Station in the Central Himalayas

1970 ◽  
Vol 8 (3) ◽  
pp. 1-10 ◽  
Author(s):  
AK Srivastava ◽  
P Pant ◽  
UC Dumka ◽  
P Hegde
Keyword(s):  
High Altitude ◽  
Black Carbon ◽  
Radiative Forcing ◽  
Lower Atmosphere ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Central Himalayas ◽  
Radiative Impact ◽  
Potential Factor ◽  
Black Carbon Aerosol

Ground-based measurements of aerosol black carbon (BC), from a high altitude location at Nainital in the central Himalayas (during June 2006 to May 2007), were used to study its temporal variability and impact on the atmospheric radiative forcing. Diurnal variation of BC mass concentration shows single enhanced peak in the late afternoon hour. The peak is rather pronounced in winter months due to shallow and stable boundary layer condition, which is largely associated with low surface temperature. The mean BC mass concentrations were found to be as ~0.6 (±0.2), 1.4 (±0.1), 1.2 (±0.3) and 1.5 (±0.2) μg m-3 during monsoon, post-monsoon, winter and spring periods, respectively while its maximum value was ~1.8 (±0.8) μg m-3 during April. The prevailing winds revealed to facilitates the transport of BC from the distant sources to the observing site. A radiative transfer model was used in conjunction with an aerosol optical model to estimate the BC radiative forcing over the station. Results show BC forcing at the top-of-atmosphere (TOA), surface and in the atmosphere varies between about +3 to +7, -6 to -14 and +8 to +21 Wm-2, respectively which is more pronounced during spring then during monsoon depending upon BC mass loading. The positive atmosphere forcing represents a considerable amount of heating to the lower atmosphere and has been conjectured as potential factor causing global warming. The estimated heating rate of the lower atmosphere over the station was found to be ranging from 0.24 Kday-1 during monsoon to 0.58 Kday-1 during spring season. DOI: http://dx.doi.org/10.3126/jie.v8i3.5926 JIE 2011; 8(3): 1-10

scholarly journals Brown carbon aerosol in the North American continental troposphere: sources, abundance, and radiative forcing

2015 ◽  
Vol 15 (5) ◽  
pp. 5959-6007 ◽  
Author(s):  
J. Liu ◽  
E. Scheuer ◽  
J. Dibb ◽  
G. S. Diskin ◽  
L. D. Ziemba ◽  
...  
Keyword(s):  
Biomass Burning ◽  
North American ◽  
Radiative Forcing ◽  
Single Scattering ◽  
Measurement Range ◽  
Radiative Transfer Model ◽  
Chemical Components ◽  
Transfer Model ◽  
Brown Carbon ◽  
The North

Abstract. Chemical components of organic aerosol selectively absorb light at short wavelengths. In this study, the prevalence, sources, and optical importance of this so-called brown carbon (BrC) aerosol component are investigated throughout the North American continental tropospheric column during a summer of extensive biomass burning. Spectrophotometric absorption measurements on extracts of bulk aerosol samples collected from an aircraft over the central USA were analyzed to directly quantify BrC abundance. BrC was found to be prevalent throughout the 1 to 12 km altitude measurement range, with dramatic enhancements in biomass burning plumes. BrC to black carbon (BC) ratios, under background tropospheric conditions, increased with altitude, consistent with a corresponding increase in the Absorption Ångström Exponent (AAE) determined from a 3-wavelength Particle Soot Absorption Photometer (PSAP). The sum of inferred BC absorption and measured BrC absorption at 365 nm was within 3% of the measured PSAP absorption for background conditions and 22% for biomass burning. A radiative transfer model showed that BrC absorption reduced top of atmosphere aerosol forcing by ~20% in the background troposphere. Extensive radiative model simulations applying this studies background tropospheric conditions provided a look-up chart for determining radiative forcing efficiencies of BrC as a function of surface-measured BrC–BC ratio and single scattering albedo (SSA). The chart is a first attempt to provide a tool for better assessment of brown carbon's forcing effect when one is limited to only surface data. These results indicate that BrC is an important component of direct aerosol radiative forcing.

scholarly journals Spatial-Temporal Variation of Snow Black Carbon Concentration in Snow Cover in Northeast China from 2001 to 2016 Based on Remote Sensing

2022 ◽  
Vol 14 (2) ◽  
pp. 959
Author(s):  
Yanjiao Zheng ◽  
Lijuan Zhang ◽  
Wenliang Li ◽  
Fan Zhang ◽  
Xinyue Zhong
Keyword(s):  
Black Carbon ◽  
Human Activities ◽  
Northeast China ◽  
Radiative Forcing ◽  
Surface Albedo ◽  
Global Climate ◽  
Atmospheric Stability ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Snow Surface

The amount of black carbon (BC) on snow surface can significantly reduce snow surface albedo in the visible-light range and change the surface radiative forcing effect. Therefore, it is key to study regional and global climate changes to understand the BC concentration on snow. In this study, we simulated the BC concentration on the surface snow of northeast China using an asymptotic radiative transfer model. From 2001 to 2016, the BC concentration showed no significant increase, with an average increase of 82.104 ng/g compared with that in the early 21st century. The concentration of BC in December was the largest (1344.588 ng/g) and decreased in January and February (1248.619 ng/g and 983.635 ng/g, respectively). The high black carbon content centers were concentrated in the eastern and central regions with dense populations and concentrated industries, with a concentration above 1200 ng/g, while the BC concentration in the southwest region with less human activities was the lowest (below 850 ng/g), which indicates that human activities played an important role in snow BC pollution. Notably, Heilongjiang province has the highest concentration, which may be related to its atmospheric stability in winter. These findings suggest that the BC pollution in northeast China has been aggravated from 2001 to 2016. It is estimated that the snow surface albedo will decrease by 16.448% due to the BC pollution of snow in northeast China. The problem of radiative forcing caused by black carbon to snow reflectivity cannot be ignored.

scholarly journals Interpreting the ultraviolet aerosol index observed with the OMI satellite instrument to understand absorption by organic aerosols: implications for atmospheric oxidation and direct radiative effects

2016 ◽  
Vol 16 (4) ◽  
pp. 2507-2523 ◽  
Author(s):  
Melanie S. Hammer ◽  
Randall V. Martin ◽  
Aaron van Donkelaar ◽  
Virginie Buchard ◽  
Omar Torres ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
South America ◽  
Biomass Burning ◽  
Southern Africa ◽  
Radiative Forcing ◽  
Transport Model ◽  
Organic Aerosol ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Aerosol Index

Abstract. Satellite observations of the ultraviolet aerosol index (UVAI) are sensitive to absorption of solar radiation by aerosols; this absorption affects photolysis frequencies and radiative forcing. We develop a global simulation of the UVAI using the 3-D chemical transport model GEOS-Chem coupled with the Vector Linearized Discrete Ordinate Radiative Transfer model (VLIDORT). The simulation is applied to interpret UVAI observations from the Ozone Monitoring Instrument (OMI) for the year 2007. Simulated and observed values are highly consistent in regions where mineral dust dominates the UVAI, but a large negative bias (−0.32 to −0.97) exists between simulated and observed values in biomass burning regions. We determine effective optical properties for absorbing organic aerosol, known as brown carbon (BrC), and implement them into GEOS-Chem to better represent observed UVAI values over biomass burning regions. The inclusion of absorbing BrC decreases the mean bias between simulated and OMI UVAI values from −0.57 to −0.09 over West Africa in January, from −0.32 to +0.0002 over South Asia in April, from −0.97 to −0.22 over southern Africa in July, and from −0.50 to +0.33 over South America in September. The spectral dependence of absorption after including BrC in the model is broadly consistent with reported observations for biomass burning aerosol, with absorbing Ångström exponent (AAE) values ranging from 2.9 in the ultraviolet (UV) to 1.3 across the UV–Near IR spectrum. We assess the effect of the additional UV absorption by BrC on atmospheric photochemistry by examining tropospheric hydroxyl radical (OH) concentrations in GEOS-Chem. The inclusion of BrC decreases OH by up to 30 % over South America in September, up to 20 % over southern Africa in July, and up to 15 % over other biomass burning regions. Global annual mean OH concentrations in GEOS-Chem decrease due to the presence of absorbing BrC, increasing the methyl chloroform lifetime from 5.62 to 5.68 years, thus reducing the bias against observed values. We calculate the direct radiative effect (DRE) of BrC using GEOS-Chem coupled with the radiative transfer model RRTMG (GC-RT). Treating organic aerosol as containing more strongly absorbing BrC changes the global annual mean all-sky top of atmosphere (TOA) DRE by +0.03 W m−2 and all-sky surface DRE by −0.08 W m−2. Regional changes of up to +0.3 W m−2 at TOA and down to −1.5 W m−2 at the surface are found over major biomass burning regions.

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