Comparison of the radiative properties and direct radiative effect of aerosols from a global aerosol model and remote sensing data over ocean

Myhre, Gunnar; Berglen, Tore Flatlandsmo; Berntsen, Terje; Boucher, Oliviér; Grini, Alf; Isaksen, I. S. A.; Johnsrud, Mona; Mishchenko, Michael I.; Stordal, Frøde; Tanré, D.

doi:10.3402/tellusb.v59i1.16973

Cited by 33 publications

(39 citation statements)

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“…Further, there may be strong local effects in regions with high aerosol loadings Haywood et al, 1999;Kaufman et al, 2002;Myhre et al, 2007;Myhre et al, 2003a, b;Yu et al, 2006). The radiative effect of aerosols in the Arctic may differ from other regions due to the high surface albedo of snow and ice and during the summer period due to the high solar zenith angle that strengthen the radiative effect of scattering aerosols (Haywood and Shine, 1997;Myhre and Stordal, 2001).…”

Section: Direct Radiative Forcing Of the May 2006 Eventmentioning

confidence: 99%

“…Hygroscopic growth is taken into account in the Mie calculations and relative humidity data are taken from ECMWF reanalysis data for the actual time period. The hygroscopic growth is taken into account for sulphate, nitrate, organic carbon, and sea salt aerosols according to Myhre et al (2007). At the 2 May the SSA is calculated to 0.98 (range between 0.980-0.982 due to variations in RH) and for 3 May the SSA range between 0.974 and 0.981 at 440 nm.…”

Section: Size Distributions and Single Scattering Albedomentioning

confidence: 99%

“…In our model we calculate the AOD based on observed chemical composition and ambient relative humidity. The hygroscopic growth is taken into account as described in Myhre et al (2007) for sulphate, nitrate, organic carbon, and sea salt (see also Sect. 3.2.2).…”

Section: Direct Radiative Forcing Of the May 2006 Eventmentioning

confidence: 99%

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Regional aerosol optical properties and radiative impact of the extreme smoke event in the European Arctic in spring 2006

et al. 2007

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Abstract. In spring 2006 a special meteorological situation occurred in the European Arctic region giving record high levels of air pollution. The synoptic situation resulted in extensive transport of pollution predominantly from agricultural fires in Eastern Europe into the Arctic region and record high air-pollution levels were measured at the Zeppelin observatory at Ny-Ålesund (78 • 54 N, 11 • 53 E) in the period from 25 April to 12 May. In the present study we investigate the optical properties of the aerosols from this extreme event and we estimate the radiative forcing of this episode.We examine the aerosol optical properties from the source region and into the European Arctic and explore the evolution of the episode and the changes in the optical properties. A number of sites in Eastern Europe, Northern Scandinavia and Svalbard are included in the study. The observations show that the maximum AOD was from 2-3 May at all sites and varies from 0.52 to 0.87, and the correspondingÅngstrøm exponent was relatively large. Lidar measurements from Minsk, ALOMAR (Arctic Lidar Observatory for Middle Atmosphere Research at Andenes) and NyAlesund show that the aerosol layer was below 3 km at all sites the height is decreasing from the source region and into the Arctic. For the AERONET sites included (Minsk, Toravere, Hornsund) we have further studied the evolution of the aerosol size. The single scattering albedo at Svalbard is proCorrespondence to: C. Lund Myhre (clm@nilu.no) vided for two sites; Ny-Ålesund and Hornsund. Importantly the calculated single scattering albedo based on the aerosol chemical composition and size distribution from Ny-Ålesund and the AERONET measurements at Hornsund are consistent. We have found strong agreement between the satellite daily MODIS AOD and the ground-based AOD observations. This agreement is crucial for accurate radiative forcing calculations. We calculate a strong negative radiative forcing for the most polluted days employing the analysed ground based data, MODIS AOD and a multi-stream model for radiative transfer of solar radiation. During this specific pollution event the forcing reached values as low as −35 W m −2 in the region. For comparison, the direct forcing of a corresponding aerosol layer with a typical AOD of 0.05 for the season is around −5 W m −2 .

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Section: Direct Radiative Forcing Of the May 2006 Eventmentioning

confidence: 99%

Section: Size Distributions and Single Scattering Albedomentioning

confidence: 99%

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Regional aerosol optical properties and radiative impact of the extreme smoke event in the European Arctic in spring 2006

et al. 2007

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“…Oslo CTM2 includes the main aerosol components (sea salt, mineral dust, sulphate, organic carbon, and black carbon) (Myhre et al, 2007). Emissions for these species and their precursors are according to AEROCOM B (http://nansen.ipsl.jussieu.fr/AEROCOM/) (Dentener et al, 2006).…”

Section: Oslo Ctm2mentioning

confidence: 99%

Aerosol-cloud interaction inferred from MODIS satellite data and global aerosol models

et al. 2007

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Abstract. We have used the MODIS satellite data and two global aerosol models to investigate the relationships between aerosol optical depth (AOD) and cloud parameters that may be affected by the aerosol concentration. The relationships that are studied are mainly between AOD, on the one hand, and cloud cover, cloud liquid water path, and water vapour, on the other. Additionally, cloud droplet effective radius, cloud optical depth, cloud top pressure and aerosol Angström exponent, have been analysed in a few cases. In the MODIS data we found, as in earlier studies, an enhancement in the cloud cover with increasing AOD. We find it likely that most of the strong increase in cloud cover with AOD, at least for AOD<0.2, is a result of aerosol-cloud interactions and a prolonged cloud lifetime. Large and mesoscale weather systems seem not to be a cause for the increase in cloud cover with AOD in this range. Sensitivity simulations show that when water uptake of the aerosols is not taken into account in the models the modelled cloud cover mostly decreases with AOD. Part of the relationship found in the MODIS data for AOD>0.2 can be explained by larger water uptake close to the clouds since relative humidity is higher in regions with higher cloud cover. The efficiency of the hygroscopic growth depends on aerosol type, the hygroscopic nature of the aerosol, the relative humidity, and to some extent the cloud screening. By analysing theÅngström exponent we find that the hygroscopic growth of the aerosol is not likely to be a main contributor to the cloud cover increase with AOD. Since the largest increase in cloud cover with Correspondence to: G. Myhre (gunnar.myhre@geo.uio.no) AOD is for low AOD (∼0.2) and thus also for low cloud cover, we argue that cloud contamination is not likely to play a large role. However, interpretation of the complex relationships between AOD and cloud parameters should be made with great care and further work is clearly needed.

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“…A 2-months spinup period was used to allow the aerosol concentrations to reach quasi-equilibrium. The aerosol optical properties are calculated using Mie theory which involves information about aerosol size, refractive index, density, as well as aerosol hygroscopic growth; see Myhre et al (2007) for more details. The carbonaceous particles are modelled as hydrophobic and hydrophilic particles with a conversion time of 2.5 days between these transported species based on Maria et al (2004).…”

Section: Universtity Of Oslo (Uio) Aerosol Model and Radiation Codementioning

confidence: 99%

Direct radiative effect of aerosols emitted by transport: from road, shipping and aviation

et al. 2010

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Abstract. Aerosols and their precursors are emitted abundantly by transport activities. Transportation constitutes one of the fastest growing activities and its growth is predicted to increase significantly in the future. Previous studies have estimated the aerosol direct radiative forcing from one transport sub-sector, but only one study to our knowledge estimated the range of radiative forcing from the main aerosol components (sulphate, black carbon (BC) and organic carbon) for the whole transportation sector. In this study, we compare results from two different chemical transport models and three radiation codes under different hypothesis of mixing: internal and external mixing using emission inventories for the year 2000. The main results from this study consist of a positive direct radiative forcing for aerosols emitted by road traffic of +20±11 mW m −2 for an externally mixed aerosol, and of +32±13 mW m −2 when BC is internally mixed. These direct radiative forcings are much higher than the previously published estimate of +3±11 mW m −2 . For transport activities from shipping, the net direct aerosol radiative forcing is negative. This forcing is dominated by the contribution of the sulphate. For both an external and an internal mixture, the radiative forcing from shipping is estimated at −26±4 mW m −2 . These estimates are in very good agreement with the range of a previously published one (from −46 to −13 mW m −2 ) but with a much narrower range. By contrast, the direct aerosol forcing from aviation is estimated to be small, and in the range −0.9 to +0.3 mW m −2 .

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Comparison of the radiative properties and direct radiative effect of aerosols from a global aerosol model and remote sensing data over ocean

Cited by 33 publications

References 0 publications

Regional aerosol optical properties and radiative impact of the extreme smoke event in the European Arctic in spring 2006

Regional aerosol optical properties and radiative impact of the extreme smoke event in the European Arctic in spring 2006

Aerosol-cloud interaction inferred from MODIS satellite data and global aerosol models

Direct radiative effect of aerosols emitted by transport: from road, shipping and aviation

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