Optical Characteristics and Radiative Properties of Aerosols in Harbin, Heilongjiang Province during 2017

This study considers aerosol optical properties and direct radiative forcing over Harbin (126.63° E, 45.75° N), the highest latitude city in Northeast China, during 2017. Observations based on the CE-318 sun-photometer show that the annual mean values of the aerosol optical depth (AOD) at 500 nm and the Angstrom exponent (AE) at 440–870 nm over Harbin are respectively 0.26 ± 0.20 and 1.36 ± 0.26. Aerosol loading is the highest in the spring followed by winter, and the lowest loading is in autumn. AE440–870 is the highest in summer, second highest in winter, and lowest in autumn. The Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model is used to estimate the shortwave aerosol radiative forcing at the top of the atmosphere, on the Earth’s surface and in the atmosphere, and the annual mean values are −16.36 ± 18.42 Wm−2, −71.01 ± 27.37 Wm−2 and 54.65 ± 30.62 Wm−2, respectively, which indicate that aerosols cause climate effects of cooling the earth-atmosphere system, cooling the earth’s surface and heating the atmosphere. Four main aerosol types in Harbin are classified via AOD and AE. Specifically, clean continental, mixed type, biomass burning and urban industry, and desert dust aerosols accounted for 51%, 38%, 9%, and 2% of the total, respectively. Aerosol radiative forcing varies greatly in different seasons, and the aerosol load and type from different emission sources have an important influence on the seasonal variation of radiative forcing.

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

10.5194/egusphere-egu2020-17044 ◽

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

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.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-2 (Bond and Bergstrom (2006)) with large uncertainties [+0.08, +1.27] Wm-2. 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-1) 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&#8217;s weak emissions at the source, but longer lifetime of aerosols in the atmosphere.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.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.

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Host model uncertainties in aerosol radiative forcing estimates: results from the AeroCom prescribed intercomparison study

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-25487-2012 ◽

2012 ◽

Vol 12 (9) ◽

pp. 25487-25549 ◽

Cited By ~ 8

Author(s):

P. Stier ◽

N. A. J. Schutgens ◽

H. Bian ◽

O. Boucher ◽

M. Chin ◽

...

Keyword(s):

Standard Deviation ◽

Radiative Forcing ◽

Radiative Properties ◽

Model Uncertainties ◽

Aerosol Radiative Forcing ◽

Aerosol Forcing ◽

Relative Standard ◽

Model Components ◽

Intercomparison Study ◽

Aerosol Radiative

Abstract. Simulated multi-model "diversity" in aerosol direct radiative forcing estimates is often perceived as measure of aerosol uncertainty. However, current models used for aerosol radiative forcing calculations vary considerably in model components relevant for forcing calculations and the associated "host-model uncertainties" are generally convoluted with the actual aerosol uncertainty. In this AeroCom Prescribed intercomparison study we systematically isolate and quantify host model uncertainties on aerosol forcing experiments through prescription of identical aerosol radiative properties in nine participating models. Even with prescribed aerosol radiative properties, simulated clear-sky and all-sky aerosol radiative forcings show significant diversity. For a purely scattering case with globally constant optical depth of 0.2, the global-mean all-sky top-of-atmosphere radiative forcing is −4.51 W m−2 and the inter-model standard deviation is 0.70 W m−2, corresponding to a relative standard deviation of 15%. For a case with partially absorbing aerosol with an aerosol optical depth of 0.2 and single scattering albedo of 0.8, the forcing changes to 1.26 W m−2, and the standard deviation increases to 1.21 W m−2, corresponding to a significant relative standard deviation of 96%. However, the top-of-atmosphere forcing variability owing to absorption is low, with relative standard deviations of 9% clear-sky and 12% all-sky. Scaling the forcing standard deviation for a purely scattering case to match the sulfate radiative forcing in the AeroCom Direct Effect experiment, demonstrates that host model uncertainties could explain about half of the overall sulfate forcing diversity of 0.13 W m−2 in the AeroCom Direct Radiative Effect experiment. Host model errors in aerosol radiative forcing are largest in regions of uncertain host model components, such as stratocumulus cloud decks or areas with poorly constrained surface albedos, such as sea ice. Our results demonstrate that host model uncertainties are an important component of aerosol forcing uncertainty that require further attention.

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Effect of Vertical Profile of Aerosols on the Local Shortwave Radiative Forcing Estimation

Atmosphere ◽

10.3390/atmos12020187 ◽

2021 ◽

Vol 12 (2) ◽

pp. 187

Author(s):

Francisco Molero ◽

Alfonso Javier Fernández ◽

María Aránzazu Revuelta ◽

Isabel Martínez-Marco ◽

Manuel Pujadas ◽

...

Keyword(s):

Vertical Distribution ◽

Vertical Profile ◽

Radiative Forcing ◽

Accurate Information ◽

Optical Parameters ◽

Aerosol Radiative Forcing ◽

Radiative Forcings ◽

Lidar Measurements ◽

Aerosol Types ◽

Aerosol Radiative

In this work, the effect of the aerosol vertical distribution on the local shortwave aerosol radiative forcing is studied. We computed the radiative forcing at the top and bottom of the atmosphere between 0.2 and 4 microns using the libRadTran package and compared the results with those provided by AERONET (AErosol RObotic NETwork). Lidar measurements were employed to characterize the aerosol vertical profile, and collocated AERONET measurements provided aerosol optical parameters required to calculate its radiative forcing. A good correlation between the calculated radiative forcings and those provide by AERONET, with differences smaller than 1 W m−2 (15% of estimated radiative forcing), is obtained when a gaussian vertical aerosol profile is assumed. Notwithstanding, when a measured aerosol profile is inserted into the model, differences between radiative forcings can vary up to 6.54 W m−2 (15%), with a mean of differences = −0.74 ± 3.06 W m−2 at BOA and −3.69 W m−2 (13%), with a mean of differences = −0.27 ± 1.32 W m−2 at TOA due to multiple aerosol layers and aerosol types. These results indicate that accurate information about aerosol vertical distribution must be incorporated in the radiative forcing calculation in order to reduce its uncertainties.

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A Method to Estimate Aerosol Radiative Forcing from Spectral Optical Depths

Journal of the Atmospheric Sciences ◽

10.1175/jas3663.1 ◽

2006 ◽

Vol 63 (3) ◽

pp. 1082-1092 ◽

Cited By ~ 30

Author(s):

S. K. Satheesh ◽

J. Srinivasan

Keyword(s):

Chemical Composition ◽

Optical Depth ◽

Radiative Forcing ◽

Field Experiments ◽

Single Scattering ◽

Single Scattering Albedo ◽

Radiative Properties ◽

Aerosol Radiative Forcing ◽

Sky Radiance ◽

Aerosol Radiative

Abstract Radiative forcing of aerosols is much more difficult to estimate than that of well-mixed gases due to the large spatial variability of aerosols and the lack of an adequate database on their radiative properties. Estimation of aerosol radiative forcing generally requires knowledge of its chemical composition, which is sparse. Ground-based sky radiance measurements [e.g., aerosol robotic network (AERONET)] can provide key parameters such as the single-scattering albedo, but in shipborne experiments over the ocean it is difficult to make sky radiance measurements and hence these experiments cannot provide parameters such as the single-scattering albedo. However, aerosol spectral optical depth data (cruise based as well as satellite retrieved) are available quite extensively over the ocean. Spectral optical depth measurements have been available since the 1970s, and spectral turbidity measurements (carried out at meteorological departments all over the world) have been available for several decades, while long-term continuous chemical composition information is not available. A new method to differentiate between scattering and absorbing aerosols is proposed here. This can be used to derive simple aerosol models that are optically equivalent and can simulate the observed aerosol optical properties and radiative fluxes, from spectral optical depth measurements. Thus, aerosol single-scattering albedo and, hence, aerosol radiative forcing can be estimated. Note that the proposed method is to estimate clear-sky aerosol radiative forcing (over regions where chemical composition data or sky radiance data are not available) and not to infer its exact chemical composition. Using several independent datasets from field experiments, it is demonstrated that the proposed method can be used to estimate aerosol radiative forcing (from spectral optical depths) with an accuracy of ±2 W m−2.

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Host model uncertainties in aerosol radiative forcing estimates: results from the AeroCom Prescribed intercomparison study

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-3245-2013 ◽

2013 ◽

Vol 13 (6) ◽

pp. 3245-3270 ◽

Cited By ~ 95

Author(s):

P. Stier ◽

N. A. J. Schutgens ◽

N. Bellouin ◽

H. Bian ◽

O. Boucher ◽

...

Keyword(s):

Standard Deviation ◽

Radiative Forcing ◽

Radiative Properties ◽

Model Uncertainties ◽

Aerosol Radiative Forcing ◽

Aerosol Forcing ◽

Relative Standard ◽

Model Components ◽

Intercomparison Study ◽

Aerosol Radiative

Abstract. Simulated multi-model "diversity" in aerosol direct radiative forcing estimates is often perceived as a measure of aerosol uncertainty. However, current models used for aerosol radiative forcing calculations vary considerably in model components relevant for forcing calculations and the associated "host-model uncertainties" are generally convoluted with the actual aerosol uncertainty. In this AeroCom Prescribed intercomparison study we systematically isolate and quantify host model uncertainties on aerosol forcing experiments through prescription of identical aerosol radiative properties in twelve participating models. Even with prescribed aerosol radiative properties, simulated clear-sky and all-sky aerosol radiative forcings show significant diversity. For a purely scattering case with globally constant optical depth of 0.2, the global-mean all-sky top-of-atmosphere radiative forcing is −4.47 Wm−2 and the inter-model standard deviation is 0.55 Wm−2, corresponding to a relative standard deviation of 12%. For a case with partially absorbing aerosol with an aerosol optical depth of 0.2 and single scattering albedo of 0.8, the forcing changes to 1.04 Wm−2, and the standard deviation increases to 1.01 W−2, corresponding to a significant relative standard deviation of 97%. However, the top-of-atmosphere forcing variability owing to absorption (subtracting the scattering case from the case with scattering and absorption) is low, with absolute (relative) standard deviations of 0.45 Wm−2 (8%) clear-sky and 0.62 Wm−2 (11%) all-sky. Scaling the forcing standard deviation for a purely scattering case to match the sulfate radiative forcing in the AeroCom Direct Effect experiment demonstrates that host model uncertainties could explain about 36% of the overall sulfate forcing diversity of 0.11 Wm−2 in the AeroCom Direct Radiative Effect experiment. Host model errors in aerosol radiative forcing are largest in regions of uncertain host model components, such as stratocumulus cloud decks or areas with poorly constrained surface albedos, such as sea ice. Our results demonstrate that host model uncertainties are an important component of aerosol forcing uncertainty that require further attention.

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Aerosol Modulation of Ultraviolet Radiation Dose over Four Metro Cities in India

Advances in Meteorology ◽

10.1155/2014/202868 ◽

2014 ◽

Vol 2014 ◽

pp. 1-5 ◽

Cited By ~ 2

Author(s):

A. S. Panicker ◽

G. Pandithurai ◽

G. Beig ◽

Dongchul Kim ◽

Dong-In Lee

Keyword(s):

Radiation Dose ◽

Radiative Forcing ◽

Internet Service ◽

Uv Index ◽

Aerosol Radiative Forcing ◽

Aerosol Forcing ◽

Emission Monitoring ◽

Different Seasons ◽

Uv Dose ◽

Aerosol Radiative

This paper discusses the influence of aerosols on UV erythemal dose over four metro cities in India. Tropospheric Emission Monitoring Internet Service (TEMIS), archived UV-index (UV-I), and UV daily erythemal dose obtained from SCIAMACHY satellite were used in this study during June 2004 and May 2005 periods covering four important Indian seasons. UV-Index (UV-I), an important parameter representing UV risk, was found to be in the high to extreme range in Chennai (8.1 to 15.33), moderate to extreme range in Mumbai and Kolkata (5 to 16.5), and low to extreme over Delhi (3 to 15). Average UV erythemal dose showed seasonal variation from 5.9 to 6.3 KJm−2during summer, 2.9 to 4.4 KJm−2during postmonsoon, 3 to 4.5 KJm−2during winter, and 5.1 to 6.19 KJm−2during premonsoon seasons over the four cities. To estimate the influence of aerosols on reducing UV dose, UV aerosol radiative forcing and forcing efficiency were estimated over the sites. The average aerosol forcing efficiency was found to be from-1.38±0.33to-3.01±0.28 KJm−2AOD−1on different seasons. The study suggests that aerosols can reduce the incoming UV radiation dose by 30–60% during different seasons.

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On the (in)accuracy of the spherical particle approximation in mineral aerosol radiative forcing simulations

Conference on Electromagnetic and Light Scattering ◽

10.1615/ichmt.2007.confelectromagligscat.210 ◽

2007 ◽

Author(s):

Michael Kahnert ◽

Timo Nousiainen ◽

Petri Raisanen

Keyword(s):

Spherical Particle ◽

Radiative Forcing ◽

Aerosol Radiative Forcing ◽

Particle Approximation ◽

Aerosol Radiative

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The Impact of Changes in Cloud Water pH on Aerosol Radiative Forcing

Geophysical Research Letters ◽

10.1029/2019gl082067 ◽

2019 ◽

Vol 46 (7) ◽

pp. 4039-4048 ◽

Cited By ~ 7

Author(s):

S. T. Turnock ◽

G. W. Mann ◽

M. T. Woodhouse ◽

M. Dalvi ◽

F. M. O'Connor ◽

...

Keyword(s):

Radiative Forcing ◽

Cloud Water ◽

Aerosol Radiative Forcing ◽

Water Ph ◽

The Impact ◽

Aerosol Radiative

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Estimates of direct radiative forcing due to aerosols from the MERRA-2 reanalysis over the Amazon region

10.5194/acp-2018-355 ◽

2018 ◽

Cited By ~ 1

Author(s):

Brunna Penna ◽

Dirceu Herdies ◽

Simone Costa

Keyword(s):

Radiative Forcing ◽

Reanalysis Data ◽

Amazon Region ◽

Reference State ◽

Aerosol Radiative Forcing ◽

Aerosol Loading ◽

Direct Radiative Forcing ◽

Direct Forcing ◽

The Difference ◽

Natural Aerosols

Abstract. Sixteen years of analysis of clear-sky direct aerosol radiative forcing is presented for the Amazon region, with calculations of AERONET network, MODIS sensor and MERRA-2 reanalysis data. The results showed that MERRA-2 reanalysis is an excellent tool for calculating and providing the spatial distribution of aerosol direct radiative forcing. In addition, the difference between considering the reference state of the atmosphere without aerosol loading and with natural aerosol to obtain the aerosol direct radiative forcing is discussed. During the dry season, the monthly average direct forcing at the top of atmosphere varied from −9.60 to −4.20 Wm−2, and at the surface, it varied from −29.81 to −9.24 Wm−2, according to MERRA-2 reanalysis data and the reference state of atmosphere without aerosol loading. Already with the state of reference being the natural aerosols, the average direct forcing at the top of atmosphere varied from −5.15 to −1.18 Wm−2, and at the surface, it varied from −21.28 to −5.25 Wm−2; this difference was associated with the absorption of aerosols.

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