Planetary Albedo Changes Due to Aerosols

Atwater, Marshall A.

doi:10.1126/science.170.3953.64

Cited by 94 publications

(42 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Single-scattering albedo (SSA or ω 0 ) is the ratio of the scattering coefficient to the extinction coefficient, measuring the relative importance of scattering and absorption. The aerosol effect on the TOA radiative budget switches from net cooling to net warming at a certain value of SSA, depending on surface albedo (e.g., Charlson and Pilat, 1969;Atwater, 1970;Mitchell Jr., 1971;Hansen et al, 1997). The angular distribution of scattering radiation is described by the phase function, i.e., a ratio of the scattered intensity at a specific direction to the integral of the scattered intensity at all directions.…”

Section: Optical Properties Determining the Aerosol Direct Effectmentioning

confidence: 99%

“…The aerosol direct radiative effect and its potential influences on climate were proposed and debated during the late 1960s and early 1970s (e.g., McCormick and Ludwig, 1967;Charlson and Pilat, 1969;Atwater, 1970;Mitchell Jr., 1971). The interactions between aerosols and solar radiation are determined by a combination of aerosol properties (loading, chemical composition, size distribution, shape), surface properties (e.g., spectral and angular variations of surface albedo), clouds (cloud fraction, optical thickness, and vertical distribution), and geographical parameters (latitude, season).…”

Section: Assessments Of Current Capabilities In Characterizing Troposmentioning

confidence: 99%

“…Aerosols participate in the Earth's energy budget directly by scattering and absorbing radiation (McCormick and Ludwig, 1967;Charlson and Pilat, 1969;Atwater, 1970;Mitchell Jr., 1971;Coakley et al, 1983) and indirectly by acting as cloud condensation nuclei and, thereby, affecting cloud properties (Twomey, 1977;Albrecht, 1989;Rosenfeld and Lensky, 1998). Moreover, the direct absorption of radiant energy by aerosols can influence the atmospheric temperature structure and, thereby, cloud formation -a phenomenon that has been labeled the semi-direct effect (Hansen et al, 1997;Ackerman et al, 2000;Koren et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A review of measurement-based assessments of the aerosol direct radiative effect and forcing

et al. 2006

View full text Add to dashboard Cite

Abstract. Aerosols affect the Earth's energy budget directly by scattering and absorbing radiation and indirectly by acting as cloud condensation nuclei and, thereby, affecting cloud properties. However, large uncertainties exist in current estimates of aerosol forcing because of incomplete knowledge concerning the distribution and the physical and chemical properties of aerosols as well as aerosol-cloud interactions. In recent years, a great deal of effort has gone into improving measurements and datasets. It is thus feasible to shift the estimates of aerosol forcing from largely model-based to increasingly measurement-based. Our goal is to assess current observational capabilities and identify uncertainties in the aerosol direct forcing through comparisons of different methods with independent sources of uncertainties. Here we assess the aerosol optical depth (τ ), direct radiative effect (DRE) by natural and anthropogenic aerosols, and direct climate forcing (DCF) by anthropogenic aerosols, focusing on satellite and ground-based measurements supplemented by global chemical transport modelCorrespondence to: H. Yu (hyu@climate.gsfc.nasa.gov) (CTM) simulations. The multi-spectral MODIS measures global distributions of aerosol optical depth (τ ) on a daily scale, with a high accuracy of ±0.03±0.05τ over ocean. The annual average τ is about 0.14 over global ocean, of which about 21%±7% is contributed by human activities, as estimated by MODIS fine-mode fraction. The multiangle MISR derives an annual average AOD of 0.23 over global land with an uncertainty of ∼20% or ±0.05. These high-accuracy aerosol products and broadband flux measurements from CERES make it feasible to obtain observational constraints for the aerosol direct effect, especially over global the ocean. A number of measurement-based approaches estimate the clear-sky DRE (on solar radiation) at the top-of-atmosphere (TOA) to be about −5.5±0.2 Wm −2 (median ± standard error from various methods) over the global ocean. Accounting for thin cirrus contamination of the satellite derived aerosol field will reduce the TOA DRE to −5.0 Wm −2 . Because of a lack of measurements of aerosol absorption and difficulty in characterizing land surface reflection, estimates of DRE over land and at the ocean surface are currently realized through a combination of satellite Published by Copernicus GmbH on behalf of the European Geosciences Union. 614H. Yu et al.: Measurement-based aerosol direct forcing retrievals, surface measurements, and model simulations, and are less constrained. Over the oceans the surface DRE is estimated to be −8.8±0.7 Wm −2 . Over land, an integration of satellite retrievals and model simulations derives a DRE of −4.9±0.7 Wm −2 and −11.8±1.9 Wm −2 at the TOA and surface, respectively. CTM simulations derive a wide range of DRE estimates that on average are smaller than the measurement-based DRE by about 30-40%, even after accounting for thin cirrus and cloud contamination.A number of issues remain. Current estimates of the aerosol direct effect ...

show abstract

Section: Optical Properties Determining the Aerosol Direct Effectmentioning

confidence: 99%

Section: Assessments Of Current Capabilities In Characterizing Troposmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A review of measurement-based assessments of the aerosol direct radiative effect and forcing

et al. 2006

View full text Add to dashboard Cite

show abstract

“…Aerosol affects the Earth and atmospheric radiation budget by directly scattering and absorbing the incoming solar radiation (McCormick and Ludwig, 1967;Charlson and Pilat, 1969;Atwater, 1970;Coakley Jr. et al, 1983) and by indirectly increasing the cloud albedo and suppressing precipitation by modifying cloud microphysical properties as cloud condensation nuclei (Twomey, 1977;Albrecht, 1989). The direct aerosol effect will influence the atmospheric temperature structure and cloud formation (Grassl, 1975;Hansen et al, 1997;Ackerman et al, 2000;Koren et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

A case study of dust aerosol radiative properties over Lanzhou, China

et al. 2010

View full text Add to dashboard Cite

Abstract. The vertical distribution of dust aerosol and its radiative properties are analysed using the data measured by the micropulse lidar, profiling microwave radiometer, sunphotometer, particulate monitor, and nephelometer at the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) during a dust storm from 27 March to 29 March 2007. The analysis shows that the dust aerosol mainly exists below 2 km in height, and the dust aerosol extinction coefficient decreases with height. The temporal evolution of aerosol optical depth (AOD) during the dust storm is characterized by a sub-maximum at 22:00 (Beijing Time), 27 March and a maximum at 12:00, 28 March. The AOD respectively derived by lidar and sunphotometer shows a good consistency. The PM 10 concentration and aerosol scattering coefficient share similar variation trends, and their maximums both appear at 22:00, 27 March.The aerosol extinction coefficient and relative humidity have the similar trends and their maximums almost appear at the same heights, which presents a correlation between extinction coefficient and relative humidity known as aerosol hygroscopicity. The relative humidity is related with temperature, and then the temperature will affect the aerosol extinction properties by modifying the relative humidity condition.The aerosol extinction coefficient, scattering coefficient, and PM 10 concentration present good linear correlations. The correlation coefficients of the aerosol scattering coefficients of 450, 520, and 700 nm and PM 10 concentration, of aerosol extinction coefficient retrieved by lidar at 532 nm and PM 10 concentration, and of aerosol extinction and scattering coefficient are respectively 0.98, 0.94, and 0.96.

show abstract

“…Atmospheric aerosol particles influence Earth's energy budget directly by scattering and absorbing radiation (McCormick and Ludwig, 1967;Charlson and Pilat, 1969;Atwater, 1970;Mitchell Jr., 1971;Coakley et al, 1983) and indirectly by acting as cloud condensation nuclei and thereby modifying cloud properties (Twomey, 1977;Albrecht, 1989;Charlson et al, 1992;Hegg, 1994;Boucher and Lohmann, 1995). A better understanding of the radiative impacts of atmospheric aerosols is needed for quantifying the factors determining Earth's energy balance and driving changes in global climate (IPCC, 2013).…”

Section: Introductionmentioning

confidence: 99%

Seasonal variation of aerosol water uptake and its impact on the direct radiative effect at Ny-Ålesund, Svalbard

et al. 2014

View full text Add to dashboard Cite

Abstract. In this study we investigated the impact of water uptake by aerosol particles in ambient atmosphere on their optical properties and their direct radiative effect (ADRE, W m −2 ) in the Arctic at Ny-Ålesund, Svalbard, during 2008. To achieve this, we combined three models, a hygroscopic growth model, a Mie model and a radiative transfer model, with an extensive set of observational data. We found that the seasonal variation of dry aerosol scattering coefficients showed minimum values during the summer season and the beginning

show abstract

Planetary Albedo Changes Due to Aerosols

Cited by 94 publications

References 5 publications

A review of measurement-based assessments of the aerosol direct radiative effect and forcing

A review of measurement-based assessments of the aerosol direct radiative effect and forcing

A case study of dust aerosol radiative properties over Lanzhou, China

Seasonal variation of aerosol water uptake and its impact on the direct radiative effect at Ny-Ålesund, Svalbard

Contact Info

Product

Resources

About