Estimation of Aerosol Radiative Forcing Over an Urban Environment Using Radiative Transfer Model

2020 ◽  
Author(s):  
Yash Dahima ◽  
Tejas Turakhia ◽  
Abha Chhabra ◽  
Rajesh Iyer
Keyword(s):  
Radiative Transfer ◽  
Urban Environment ◽  
Radiative Forcing ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Aerosol Radiative Forcing ◽  
Aerosol Radiative

scholarly journals Aerosol radiative forcing during African desert dust events (2005–2010) over South-Eastern Spain

2012 ◽  
Vol 12 (3) ◽  
pp. 6593-6622 ◽  
Author(s):  
A. Valenzuela ◽  
F. J. Olmo ◽  
H. Lyamani ◽  
M. Antón ◽  
A. Quirantes ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Radiative Forcing ◽  
Single Scattering ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Aerosol Radiative Forcing ◽  
Desert Dust ◽  
Aerosol Parameter ◽  
Dust Events ◽  
Aerosol Radiative

Abstract. The instantaneous values of the aerosol radiative forcing (ARF) at the surface and the top of the atmosphere (TOA) were calculated during desert dust events occurred at Granada (Southeastern Spain) from 2005 to 2010. For that, the SBDART radiative transfer model was utilized to simulate the global irradiance values (0.3–2.8 μm) at the surface and TOA using as input the aerosol properties derived from a CIMEL sun-photometer measurements and an inversion methodology that uses the sky radiance measurements in principal plane configuration and non-spherical particle shapes approximation. The SBDART modeled global irradiances at surface have been successfully validated against experimental measurements obtained by CM-11 pyranometer, indicating the reliability of the radiative transfer model used in this work for the ARF calculations. The monthly ARF values at surface ranged from −32 W m−2 to −46 W m−2, being larger in April and July than in the rest of months. The seasonal ARF evolution was inconsistent with seasonal aerosol optical depth (AOD) variation due to the effects induced by other aerosol parameter such as the single scattering albedo. The ARF at TOA changed from −9 W m−2 to −29 W m−2. Thus, the atmospheric ARF values (ARF at TOA minus ARF at surface) ranged from +15 to +35 W m−2. These results suggest that the African dust caused local atmospheric heating over the study location. The instantaneous aerosol radiative forcing efficiency (ARFE), aerosol radiative forcing per unit of AOD (440 nm), at surface and TOA during African desert dust events was evaluated according to the desert dust source origins. The ARFE values at surface were relatively high (in absolute term) and were −157 ± 20 (Sector A), −154 ± 23 (Sector B), and −147 ± 23 (Sector C) W m−2. These values were larger than many of the values found in literature which could be due to the presence of more absorbing atmospheric particles during African desert dust intrusions over our study area. Finally, our ARF computations showed good agreement with the corresponding ARF calculated by AERONET network.

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 Aerosol radiative forcing during African desert dust events (2005–2010) over Southeastern Spain

2012 ◽  
Vol 12 (21) ◽  
pp. 10331-10351 ◽  
Author(s):  
A. Valenzuela ◽  
F. J. Olmo ◽  
H. Lyamani ◽  
M. Antón ◽  
A. Quirantes ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Aerosol Optical Properties ◽  
Aerosol Radiative Forcing ◽  
Desert Dust ◽  
The Mean ◽  
Dust Events ◽  
Aerosol Properties ◽  
Aerosol Radiative

Abstract. The daily (24 h) averages of the aerosol radiative forcing (ARF) at the surface and the top of the atmosphere (TOA) were calculated during desert dust events over Granada (southeastern Spain) from 2005 to 2010. A radiative transfer model (SBDART) was utilized to simulate the solar irradiance values (0.31–2.8 μm) at the surface and TOA, using as input aerosol properties retrieved from CIMEL sun photometer measurements via an inversion methodology that uses the sky radiance measurements in principal plane configuration and a spheroid particle shape approximation. This inversion methodology was checked by means of simulated data from aerosol models, and the derived aerosol properties were satisfactorily compared against well-known AERONET products. Good agreement was found over a common spectral interval (0.2–4.0 μm) between the simulated SBDART global irradiances at surface and those provided by AERONET. In addition, simulated SBDART solar global irradiances at the surface have been successfully validated against CM-11 pyranometer measurements. The comparison indicates that the radiative transfer model slightly overestimates (mean bias of 3%) the experimental solar global irradiance. These results show that the aerosol optical properties used to estimate ARF represent appropriately the aerosol properties observed during desert dust outbreak over the study area. The ARF mean monthly values computed during desert dust events ranged from −13 ± 8 W m−2 to −34 ± 15 W m−2 at surface, from −4 ± 3 W m−2 to −13 ± 7 W m−2 at TOA and from +6 ± 4 to +21 ± 12 W m−2 in the atmosphere. We have checked if the differences found in aerosol optical properties among desert dust sectors translate to differences in ARF. The mean ARF at surface (TOA) were −20 ± 12 (−5 ± 5) W m−2, −21 ± 9 (−7 ± 5) W m−2 and −18 ± 9 (−6 ± 5) W m−2 for sector A (northern Morocco; northwestern Algeria), sector B (western Sahara, northwestern Mauritania and southwestern Algeria), and sector C (eastern Algeria, Tunisia), respectively. The Kolmogorov-Smirnov statistical test revealed that daily {ARF} values at TOA for sector A were significantly different from the other two sectors, likely as a result of the lower values of single scattering albedo obtained for sector A. The mean values of aerosol radiative forcing efficiency at surface (TOA) were −74 ± 12 W m−2 (−17 ± 7 W m−2) for sector A, −70 ± 14 W m−2 (−20 ± 9 W m−2) for sector B, and −65 ± 16 W m−2 (−22 ± 10 W m−2) for sector C, and thus comparable between the three sectors in all seasons.

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>

Greenhouse effects of aircraft emissions as calculated by a radiative transfer model

1995 ◽  
Vol 13 (4) ◽  
pp. 413-418 ◽  
Author(s):  
J. P. F. Fortuin ◽  
R. van Dorland ◽  
W. M. F. Wauben ◽  
H. Kelder
Keyword(s):  
Water Vapor ◽  
Radiative Transfer ◽  
Indirect Effect ◽  
Radiative Forcing ◽  
Combustion Products ◽  
Ozone Production ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Aircraft Emissions ◽  
The North

Abstract. With a radiative transfer model, assessments are made of the radiative forcing in northern mid-latitudes due to aircraft emissions up to 1990. Considered are the direct climate effects from the major combustion products carbon dioxide, nitrogen dioxide, water vapor and sulphur dioxide, as well as the indirect effect of ozone production from NOx emissions. Our study indicates a local radiative forcing at the tropopause which should be negative in summer (–0.5 to 0.0 W/m2) and either negative or positive in winter (–0.3 to 0.2 W/m2). To these values the indirect effect of contrails has to be added, which for the North Atlantic Flight Corridor covers the range –0.2 to 0.3 W/m2 in summer and 0.0 to 0.3 W/m2 in winter. Apart from optically dense non-aged contrails during summer, negative forcings are due to solar screening by sulphate aerosols. The major positive contributions come from contrails, stratospheric water vapor in winter and ozone in summer. The direct effect of NO2 is negligible and the contribution of CO2 is relatively small.

scholarly journals Improved estimate of global dust radiative forcing using a coupled chemical transport-radiative transfer model

2013 ◽  
Vol 13 (1) ◽  
pp. 2415-2456 ◽  
Author(s):  
L. Zhang ◽  
Q. B. Li ◽  
Y. Gu ◽  
K. N. Liou ◽  
B. Meland
Keyword(s):  
Radiative Transfer ◽  
Vertical Profile ◽  
Radiative Forcing ◽  
Chemical Transport ◽  
Dust Particles ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Vertical Profiles ◽  
Dust Source ◽  
Source Regions

Abstract. Atmospheric mineral dust particles exert significant direct radiative forcings and are critical drivers of climate change. Here, we use the GEOS-Chem global three-dimensional chemical transport model (3-D CTM) coupled online with the Fu-Liou-Gu (FLG) radiative transfer model (RTM) to investigate the dust radiative forcing and heating rates based on different dust vertical profiles. The coupled calculations using a realistic dust vertical profile simulated by GEOS-Chem minimize the physical inconsistencies between 3-D CTM aerosol fields and the RTM. The use of GEOS-Chem simulated aerosol optical depth (AOD) vertical profiles as opposed to the FLG prescribed AOD vertical profiles leads to greater and more spatially heterogeneous changes in estimated radiative forcing and heating rate produced by dust. Both changes can be attributed to a different vertical structure between dust and non-dust source regions. Values of the dust AOD are much larger in the middle troposphere, though smaller at the surface when the GEOS-Chem simulated AOD vertical profile is used, which leads to a much stronger heating rate in the middle troposphere. Compared to FLG vertical profile, the use of GEOS-Chem vertical profile reduces the solar radiative forcing effect by about 0.2–0.25 W m−2 and the Infrared (IR) radiative forcing over the African and Asia dust source regions by about 0.1–0.2 W m−2. Differences in the solar radiative forcing at the surface between using the GEOS-Chem vertical profile and the FLG vertical profile are most significant over the Gobi desert with a value of about 1.1 W m−2. The radiative forcing effect of dust particles is more pronounced at the surface over the Sahara and Gobi deserts by using FLG vertical profile, while it is less significant over the downwind area of Eastern Asia.

scholarly journals Intercomparison of shortwave radiative transfer schemes in global aerosol modeling: results from the AeroCom Radiative Transfer Experiment

2012 ◽  
Vol 12 (12) ◽  
pp. 32631-32706 ◽  
Author(s):  
C. A. Randles ◽  
S. Kinne ◽  
G. Myhre ◽  
M. Schulz ◽  
P. Stier ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Multiple Scattering ◽  
Radiative Forcing ◽  
Model Performance ◽  
Aerosol Radiative Forcing ◽  
Aerosol Forcing ◽  
Aerosol Absorption ◽  
Relative Standard ◽  
Aerosol Modeling ◽  
Aerosol Radiative

Abstract. In this study we examine the performance of 31 global model radiative transfer schemes in cloud-free conditions with prescribed gaseous absorbers and no aerosols (Rayleigh atmosphere), with prescribed scattering-only aerosols, and with more absorbing aerosols. Results are compared to benchmark results from high-resolution, multi-angular line-by-line radiation models. For purely scattering aerosols, model bias relative to the line-by-line models in the top-of-the atmosphere aerosol radiative forcing ranges from roughly −10 to 20%, with over- and underestimates of radiative cooling at higher and lower sun elevation, respectively. Inter-model diversity (relative standard deviation) increases from ~10 to 15% as sun elevation increases. Inter-model diversity in atmospheric and surface forcing decreases with increased aerosol absorption, indicating that the treatment of multiple-scattering is more variable than aerosol absorption in the models considered. Aerosol radiative forcing results from multi-stream models are generally in better agreement with the line-by-line results than the simpler two-stream schemes. Considering radiative fluxes, model performance is generally the same or slightly better than results from previous radiation scheme intercomparisons. However, the inter-model diversity in aerosol radiative forcing remains large, primarily as a result of the treatment of multiple-scattering. Results indicate that global models that estimate aerosol radiative forcing with two-stream radiation schemes may be subject to persistent biases introduced by these schemes, particularly for regional aerosol forcing.

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.

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