scholarly journals Impact of the Atmospheric Photochemical Evolution of the Organic Component of Biomass Burning Aerosol on Its Radiative Forcing Efficiency: A Box Model Analysis

Atmosphere ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1555
Author(s):  
Tatiana B. Zhuravleva ◽  
Ilmir M. Nasrtdinov ◽  
Igor B. Konovalov ◽  
Nikolai A. Golovushkin ◽  
Matthias Beekmann
Keyword(s):  
Biomass Burning ◽  
Radiative Forcing ◽  
Model Simulation ◽  
Single Scattering ◽  
Box Model ◽  
Basis Set ◽  
Organic Component ◽  
Asymmetry Factor ◽  
Aerosol Radiative Forcing ◽  
Simulation Results

We present the first box model simulation results aimed at identification of possible effects of the atmospheric photochemical evolution of the organic component of biomass burning (BB) aerosol on the aerosol radiative forcing (ARF) and its efficiency (ARFE). The simulations of the dynamics of the optical characteristics of the organic aerosol (OA) were performed using a simple parameterization developed within the volatility basis set framework and adapted to simulate the multiday BB aerosol evolution in idealized isolated smoke plumes from Siberian fires (without dilution). Our results indicate that the aerosol optical depth can be used as a good proxy for studying the effect of the OA evolution on the ARF, but variations in the scattering and absorbing properties of BB aerosol can also affect its radiative effects, as evidenced by variations in the ARFE. Changes in the single scattering albedo (SSA) and asymmetry factor, which occur as a result of the BB OA photochemical evolution, may either reduce or enhance the ARFE as a result of their competing effects, depending on the initial concentration OA, the ratio of black carbon to ОА mass concentrations and the aerosol photochemical age in a complex way. Our simulation results also reveal that (1) the ARFE at the top of the atmosphere is not significantly affected by the OA oxidation processes compared to the ARFE at the bottom of the atmosphere, and (2) the dependence of ARFE in the atmospheric column and on the BB aerosol photochemical ages almost mirrors the corresponding dependence of SSA.

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.

Improved estimates of future fire emissions under CMIP6 scenarios and implications for aerosol radiative forcing

2021 ◽  
Author(s):  
Matthew Kasoar ◽  
Douglas Hamilton ◽  
Daniela Dalmonech ◽  
Stijn Hantson ◽  
Gitta Lasslop ◽  
...  
Keyword(s):  
Machine Learning ◽  
Biomass Burning ◽  
Radiative Forcing ◽  
Learning Methods ◽  
Aerosol Radiative Forcing ◽  
Fire Emissions ◽  
Machine Learning Methods ◽  
The Tropics ◽  
In Fire ◽  
Aerosol Radiative

<p>The CMIP6 Shared Socioeconomic Pathway (SSP) scenarios include projections of future changes in anthropogenic biomass-burning.  Globally, they assume a decrease in total fire emissions over the next century under all scenarios.  However, fire regimes and emissions are expected to additionally change with future climate, and the methodology used to project fire emissions in the SSP scenarios is opaque.</p><p>We aim to provide a more traceable estimate of future fire emissions under CMIP6 scenarios and evaluate the impacts for aerosol radiative forcing.  We utilise interactive wildfire emissions from four independent land-surface models (CLM5, JSBACH3.2, LPJ-GUESS, and ISBA-CTRIP) used within CMIP6 ESMs, and two different machine-learning methods (a random forest, and a generalised additive model) trained on historical data, to predict year 2100 biomass-burning aerosol emissions consistent with the CMIP6-modelled climate for three different scenarios: SSP126, SSP370, and SSP585.  This multi-method approach provides future fire emissions integrating information from observations, projections of climate, socioeconomic parameters and changes in vegetation distribution and fuel loads.</p><p>Our analysis shows a robust increase in fire emissions for large areas of the extra-tropics until the end of this century for all methods.  Although this pattern was present to an extent in the original SSP projections, both the interactive fire models and machine-learning methods predict substantially higher increases in extra-tropical emissions in 2100 than the corresponding SSP datasets.  Within the tropics the signal is mixed. Increases in emissions are largely driven by the temperature changes, while in some tropical areas reductions in fire emissions are driven by human factors and changes in precipitation, with the largest reductions in Africa. The machine-learning methods show a stronger reduction in the tropics than the interactive fire models, however overall there is strong agreement between both the models and the machine-learning methods.</p><p>We then use additional nudged atmospheric simulations with two state-of-the-art composition-climate models, UKESM1 and CESM2, to diagnose the impact of these updated fire emissions on aerosol burden and radiative forcing, compared with the original SSP prescribed emissions.  We provide estimates of future fire radiative forcing, compared to modern-day, under these CMIP6 scenarios which span both the severity of climate change in 2100, and the rate of reduction of other aerosol species.</p>

scholarly journals Contrasting variation in aerosol optical properties during dust episodes in the Middle East and Southwest Asia: Model results and ground measurement

2019 ◽  
Vol 99 ◽  
pp. 04006
Author(s):  
Khan Alam ◽  
Maqbool Ahmad
Keyword(s):  
Middle East ◽  
Radiative Forcing ◽  
Single Scattering ◽  
Dust Storms ◽  
Radiative Properties ◽  
Southwest Asia ◽  
Gulf Region ◽  
Aerosol Radiative Forcing ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Using Data

Dust storms deteriorated air quality over the Gulf Region, Iraq, Iran, and Pakistan during the last decade. The purpose of this study is to investigate the changes in aerosol optical and radiative properties during a dust episode over the various locations in the Middle East and Southwest Asia using data from the MODerate resolution Imaging Spectroradiometer (MODIS) and the Aerosol Robotic Network (AERONET) during March, 2012. Maximum aerosol optical depth (AOD) values were found to be 2.18, 1.30, 4.33 and 1.80 over Lahore, Kanpur, Kaust, and Mezaira, respectively. The Volume Size Distributions, Single Scattering Albedo, Refractive Index, and Asymmetry parameter indicated that coarse mode aerosols were predominant relative to fine mode aerosols during the dust event. The average shortwave aerosol radiative forcing (ARF) values at the earth’s surface were found to be -96±45 W m-2, -86±22 W m-2, -77±51 W m-2, and -75±40 W m-2, over Lahore, Kanpur, Kaust and Mezaira, respectively. Likewise, the averaged ARF values over Lahore, Kanpur, Kaust and Mezaira at the top of the atmosphere (TOA) were found to be -45±25 W m-2, -27±9 W m-2, -41±29 W m-2, and -75±40 W m-2, respectively. The large differences between surface and TOA forcing produced significant heating within the atmosphere.

scholarly journals Direct Aerosol Radiative Forcing Uncertainty Based on a Radiative Perturbation Analysis

2010 ◽  
Vol 23 (19) ◽  
pp. 5288-5293 ◽  
Author(s):  
Norman G. Loeb ◽  
Wenying Su
Keyword(s):  
Radiative Forcing ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Aerosol Radiative Forcing ◽  
Clear Sky ◽  
Radiative Perturbation ◽  
Sky Conditions ◽  
Global Mean ◽  
Aerosol Properties ◽  
Aerosol Radiative

Abstract To provide a lower bound for the uncertainty in measurement-based clear- and all-sky direct aerosol radiative forcing (DARF), a radiative perturbation analysis is performed for the ideal case in which the perturbations in global mean aerosol properties are given by published values of systematic uncertainty in Aerosol Robotic Network (AERONET) aerosol measurements. DARF calculations for base-state climatological cloud and aerosol properties over ocean and land are performed, and then repeated after perturbing individual aerosol optical properties (aerosol optical depth, single-scattering albedo, asymmetry parameter, scale height, and anthropogenic fraction) from their base values, keeping all other parameters fixed. The total DARF uncertainty from all aerosol parameters combined is 0.5–1.0 W m−2, a factor of 2–4 greater than the value cited in the Intergovernmental Panel on Climate Change’s (IPCC’s) Fourth Assessment Report. Most of the total DARF uncertainty in this analysis is associated with single-scattering albedo uncertainty. Owing to the greater sensitivity to single-scattering albedo in cloudy columns, DARF uncertainty in all-sky conditions is greater than in clear-sky conditions, even though the global mean clear-sky DARF is more than twice as large as the all-sky DARF.

scholarly journals Intercomparison of biomass burning aerosol optical properties from in situ and remote-sensing instruments in ORACLES-2016

2019 ◽  
Vol 19 (14) ◽  
pp. 9181-9208 ◽  
Author(s):  
Kristina Pistone ◽  
Jens Redemann ◽  
Sarah Doherty ◽  
Paquita Zuidema ◽  
Sharon Burton ◽  
...  
Keyword(s):  
Optical Properties ◽  
Case Studies ◽  
Biomass Burning ◽  
Radiative Forcing ◽  
Measurement Techniques ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Aerosol Optical Properties ◽  
Biomass Burning Aerosol

Abstract. The total effect of aerosols, both directly and on cloud properties, remains the biggest source of uncertainty in anthropogenic radiative forcing on the climate. Correct characterization of intensive aerosol optical properties, particularly in conditions where absorbing aerosol is present, is a crucial factor in quantifying these effects. The southeast Atlantic Ocean (SEA), with seasonal biomass burning smoke plumes overlying and mixing with a persistent stratocumulus cloud deck, offers an excellent natural laboratory to make the observations necessary to understand the complexities of aerosol–cloud–radiation interactions. The first field deployment of the NASA ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) campaign was conducted in September of 2016 out of Walvis Bay, Namibia. Data collected during ORACLES-2016 are used to derive aerosol properties from an unprecedented number of simultaneous measurement techniques over this region. Here, we present results from six of the eight independent instruments or instrument combinations, all applied to measure or retrieve aerosol absorption and single-scattering albedo. Most but not all of the biomass burning aerosol was located in the free troposphere, in relative humidities typically ranging up to 60 %. We present the single-scattering albedo (SSA), absorbing and total aerosol optical depth (AAOD and AOD), and absorption, scattering, and extinction Ångström exponents (AAE, SAE, and EAE, respectively) for specific case studies looking at near-coincident and near-colocated measurements from multiple instruments, and SSAs for the broader campaign average over the month-long deployment. For the case studies, we find that SSA agrees within the measurement uncertainties between multiple instruments, though, over all cases, there is no strong correlation between values reported by one instrument and another. We also find that agreement between the instruments is more robust at higher aerosol loading (AOD400>0.4). The campaign-wide average and range shows differences in the values measured by each instrument. We find the ORACLES-2016 campaign-average SSA at 500 nm (SSA500) to be between 0.85 and 0.88, depending on the instrument considered (4STAR, AirMSPI, or in situ measurements), with the interquartile ranges for all instruments between 0.83 and 0.89. This is consistent with previous September values reported over the region (between 0.84 and 0.90 for SSA at 550nm). The results suggest that the differences observed in the campaign-average values may be dominated by instrument-specific spatial sampling differences and the natural physical variability in aerosol conditions over the SEA, rather than fundamental methodological differences.

scholarly journals Diurnal aerosol variations do affect daily averaged radiative forcing under heavy aerosol loading observed in Hefei, China

2015 ◽  
Vol 8 (7) ◽  
pp. 2901-2907 ◽  
Author(s):  
Z. Wang ◽  
D. Liu ◽  
Y. Wang ◽  
Z. Wang ◽  
G. Shi
Keyword(s):  
Temporal Resolution ◽  
Radiative Forcing ◽  
Single Scattering ◽  
High Temporal Resolution ◽  
Diurnal Changes ◽  
Data Set ◽  
Time Resolved ◽  
Aerosol Radiative Forcing ◽  
Aerosol Loading

Abstract. A strong diurnal variation of aerosol has been observed in many heavily polluted regions in China. This variation could affect the direct aerosol radiative forcing (DARF) evaluation if the daily averaged value is used as normal rather than the time-resolved values. To quantify the effect of using the daily averaged DARF, 196 days of high temporal resolution ground-based data collected in SKYNET Hefei site during the period from 2007 to 2013 is used to perform an assessment. We demonstrate that strong diurnal changes of heavy aerosol loading have an impact on the 24-h averaged DARF when daily averaged optical properties are used to retrieve this quantity. The DARF errors varying from −7.6 to 15.6 W m−2 absolutely and from 0.1 to 28.5 % relatively were found between the calculations using daily average aerosol properties, and those using time-resolved aerosol observations. These errors increase with increasing daily aerosol optical depth (AOD) and decreasing daily single-scattering albedo (SSA), indicating that the high temporal resolution DARF data set should be used in the model instead of the normal daily-averaged one, especially under heavy aerosol loading conditions for regional campaign studies. We also found that statistical errors (0.3 W m−2 absolutely and 11.8 % relatively) will be less, which means that the effect of using the daily averaged DARF can be weakened by using a long-term observational data set.

scholarly journals Retrieval of Key Aerosol Optical Parameters from Spectral Direct and Diffuse Irradiances Observed by a Radiometer with Nonideal Cosine Response Characteristic

2012 ◽  
Vol 29 (5) ◽  
pp. 683-696 ◽  
Author(s):  
Pradeep Khatri ◽  
Tamio Takamura ◽  
Akihiro Yamazaki ◽  
Yutaka Kondo
Keyword(s):  
Direct Effect ◽  
Radiative Forcing ◽  
Response Characteristic ◽  
Single Scattering ◽  
Optical Parameters ◽  
Aerosol Radiative Forcing ◽  
Aerosol Direct Effect ◽  
Diffuse Irradiance ◽  
Isotropic Distribution ◽  
Sky Radiance

Abstract The spectral direct and diffuse irradiances observed by a radiometer with a horizontal surface detector have been frequently used to study aerosol optical parameters, such as aerosol optical thickness (τaer) and single scattering albedo (ω). Such radiometers more or less lack an ideal cosine response. Generally, either the cosine error of observed diffuse irradiance was corrected by assuming an isotropic distribution of sky radiance or it was neglected in the past studies. This study presents an algorithm to retrieve τaer and ω from direct and diffuse irradiances observed by a radiometer with a nonideal cosine response characteristic by taking into account the cosine errors of observed irradiances in detail. The proposed algorithm considers the anisotropic distribution of sky radiance while correcting the cosine error of observed diffuse irradiance. This algorithm can also be used to calculate the cosine error correction factor of diffuse irradiance. The results show that the aerosol optical parameters and the aerosol direct effect (aerosol radiative forcing and the heating rate) can be heavily affected by the cosine errors of observed direct and diffuse irradiances. The study further shows that assuming the isotropic distribution of sky radiance while correcting the cosine error of observed diffuse irradiance can affect the retrieved ω at small and large solar zenith angles; thus, the estimated aerosol direct effect can be quantitatively affected. Because of the cosine errors, this study found the actual values of diffuse irradiances at different wavelengths were underestimated by around 5%–11%.

scholarly journals Observations and Modeling of the Surface Aerosol Radiative Forcing during UAE2

2008 ◽  
Vol 65 (9) ◽  
pp. 2877-2891 ◽  
Author(s):  
K. M. Markowicz ◽  
P. J. Flatau ◽  
J. Remiszewska ◽  
M. Witek ◽  
E. A. Reid ◽  
...  
Keyword(s):  
United Arab Emirates ◽  
Radiative Forcing ◽  
Sea Breeze ◽  
Single Scattering ◽  
Land Breeze ◽  
Gulf Region ◽  
Diurnal Variability ◽  
Aerosol Radiative Forcing ◽  
Aerosol Forcing ◽  
Aerosol Radiative

Abstract Aerosol radiative forcing in the Persian Gulf region is derived from data collected during the United Arab Emirates (UAE) Unified Aerosol Experiment (UAE2). This campaign took place in August and September of 2004. The land–sea-breeze circulation modulates the diurnal variability of the aerosol properties and aerosol radiative forcing at the surface. Larger aerosol radiative forcing is observed during the land breeze in comparison to the sea breeze. The aerosol optical properties change as the onshore wind brings slightly cleaner air. The mean diurnal value of the surface aerosol forcing during the UAE2 campaign is about −20 W m−2, which corresponds to large aerosol optical thickness (0.45 at 500 nm). The aerosol forcing efficiency [i.e., broadband shortwave forcing per unit optical depth at 550 nm, W m−2 (τ500)−1] is −53 W m−2 (τ500)−1 and the average single scattering albedo is 0.93 at 550 nm.

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