scholarly journals Aerosol radiative effects in the ultraviolet, visible, and near-infrared spectral ranges using long-term aerosol data series over the Iberian Peninsula

2014 ◽  
Vol 14 (24) ◽  
pp. 13497-13514 ◽  
Author(s):  
D. Mateos ◽  
M. Antón ◽  
C. Toledano ◽  
V. E. Cachorro ◽  
L. Alados-Arboledas ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Near Infrared ◽  
Fine Particles ◽  
Radiative Properties ◽  
Radiative Effects ◽  
Spectral Ranges ◽  
Aerosol Radiative Effects ◽  
Aerosol Types ◽  
Aerosol Radiative

Abstract. A better understanding of aerosol radiative properties is a crucial challenge for climate change studies. This study aims at providing a complete characterization of aerosol radiative effects in different spectral ranges within the shortwave (SW) solar spectrum. For this purpose, long-term data sets of aerosol properties from six AERONET stations located in the Iberian Peninsula (southwestern Europe) have been analyzed in terms of climatological characterization and inter-annual changes. Aerosol information was used as input for the libRadtran model in order to determine the aerosol radiative effect (ARE) at the surface in the ultraviolet (AREUV), visible (AREVIS), near-infrared (ARENIR), and the entire SW range (ARESW) under cloud-free conditions. Over the whole Iberian Peninsula, yearly aerosol radiative effects in the different spectral ranges were found to be −1.1 < AREUV < −0.7, −5.7 < AREVIS < −3.5, −2.6 < ARENIR < −1.6, and −8.8 < ARESW < −5.7 (in W m−2). Monthly means of ARE showed a seasonal pattern with larger values in spring and summer. The aerosol forcing efficiency (AFE), ARE per unit of aerosol optical depth, has also been evaluated in the four spectral ranges. AFE exhibited a dependence on single scattering albedo as well as a weaker one on the Ångström exponent. AFE is larger (in absolute value) for small and absorbing particles. The contributions of the UV, VIS, and NIR ranges to the SW efficiency varied with the aerosol types. The predominant aerosol size determined the fractions AFEVIS/AFESW and AFENIR/AFESW. The AFEVIS was the dominant contributor for all aerosol types, although non-absorbing large particles caused more even contribution of VIS and NIR intervals. The AFEUV / AFESW ratio showed a higher value in the case of absorbing fine particles.

scholarly journals Aerosol radiative effects in the ultraviolet, visible, and near-infrared spectral ranges using long-term aerosol data series over the Iberian Peninsula

2014 ◽  
Vol 14 (7) ◽  
pp. 8779-8818 ◽  
Author(s):  
D. Mateos ◽  
M. Antón ◽  
C. Toledano ◽  
V. E. Cachorro ◽  
L. Alados-Arboledas ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Near Infrared ◽  
Radiative Properties ◽  
Radiative Effects ◽  
Spectral Ranges ◽  
Aerosol Radiative Effects ◽  
Aerosol Radiative

Abstract. A better understanding of the aerosol radiative properties is a crucial challenge for climate change studies. This study aims to provide a complete characterization of aerosol radiative effects in different spectral ranges within the shortwave (SW) solar spectrum. For this purpose, long-term datasets of aerosol properties from six AERONET stations located in the Iberian Peninsula (Southwestern Europe) are analyzed in term of climatology characterization and trends. Aerosol information is used as input to the libRadtran model in order to determine the aerosol radiative effect at the surface in the ultraviolet (AREUV), visible (AREVIS), near-infrared (ARENIR), and the entire SW range (ARESW) under cloud-free conditions. Over the whole Iberian Peninsula, aerosol radiative effects in the different spectral ranges are: −1.1 < AREUV < −0.7 W m−2, −5.7 < AREVIS < −3.8 W m−2, −2.8 < ARENIR < −1.7 W m−2, and −9.5 < ARESW < −6.1 W m−2. The four variables showed positive statistically significant trends between 2004 and 2012, e.g., ARESW increased +3.6 W m−2 per decade. This fact is linked to the decrease in the aerosol load, which presents a trend of −0.04 per unit of aerosol optical depth at 500 nm per decade, hence a reduction of aerosol effect on solar radiation at the surface is seen. Monthly means of ARE show a seasonal pattern with larger values in spring and summer. The aerosol forcing efficiency (AFE), ARE per unit of aerosol optical depth, is also evaluated in the four spectral ranges. AFE exhibits a dependence on single scattering albedo and a weaker one on Ångström exponent. AFE is larger (in absolute value) for small and absorbing particles. The contributions of the UV, VIS, and NIR ranges to the SW efficiency vary with the aerosol types. Aerosol size determines the fractions of AFEVIS/AFESW and AFENIR/AFESW. VIS range is the dominant region for all types, although non-absorbing large particles cause a more equal contribution of VIS and NIR intervals. The AFEUV / AFESW ratio shows a higher contribution for absorbing fine particles.

scholarly journals Estimations of global shortwave direct aerosol radiative effects above opaque water clouds using a combination of A-Train satellite sensors

2019 ◽  
Vol 19 (7) ◽  
pp. 4933-4962 ◽  
Author(s):  
Meloë S. Kacenelenbogen ◽  
Mark A. Vaughan ◽  
Jens Redemann ◽  
Stuart A. Young ◽  
Zhaoyan Liu ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Radiative Properties ◽  
Ratio Method ◽  
Northwest Pacific ◽  
Radiative Effects ◽  
Cloud Properties ◽  
Satellite Sensors ◽  
Level 1 ◽  
Aerosol Radiative Effects ◽  
Aerosol Radiative

Abstract. All-sky direct aerosol radiative effects (DARE) play a significant yet still uncertain role in climate. This is partly due to poorly quantified radiative properties of aerosol above clouds (AAC). We compute global estimates of shortwave top-of-atmosphere DARE over opaque water clouds (OWCs), DAREOWC, using observation-based aerosol and cloud radiative properties from a combination of A-Train satellite sensors and a radiative transfer model. There are three major differences between our DAREOWC calculations and previous studies: (1) we use the depolarization ratio method (DR) on CALIOP (Cloud–Aerosol Lidar with Orthogonal Polarization) Level 1 measurements to compute the AAC frequencies of occurrence and the AAC aerosol optical depths (AODs), thus introducing fewer uncertainties compared to using the CALIOP standard product; (2) we apply our calculations globally, instead of focusing exclusively on regional AAC “hotspots” such as the southeast Atlantic; and (3) instead of the traditional look-up table approach, we use a combination of satellite-based sensors to obtain AAC intensive radiative properties. Our results agree with previous findings on the dominant locations of AAC (south and northeast Pacific, tropical and southeast Atlantic, northern Indian Ocean and northwest Pacific), the season of maximum occurrence and aerosol optical depths (a majority in the 0.01–0.02 range and that can exceed 0.2 at 532 nm) across the globe. We find positive averages of global seasonal DAREOWC between 0.13 and 0.26 W m−2 (i.e., a warming effect on climate). Regional seasonal DAREOWC values range from −0.06 W m−2 in the Indian Ocean offshore from western Australia (in March–April–May) to 2.87 W m−2 in the southeast Atlantic (in September–October–November). High positive values are usually paired with high aerosol optical depths (>0.1) and low single scattering albedos (<0.94), representative of, for example, biomass burning aerosols. Because we use different spatial domains, temporal periods, satellite sensors, detection methods and/or associated uncertainties, the DAREOWC estimates in this study are not directly comparable to previous peer-reviewed results. Despite these differences, we emphasize that the DAREOWC estimates derived in this study are generally higher than previously reported. The primary reasons for our higher estimates are (i) the possible underestimate of the number of dust-dominated AAC cases in our study; (ii) our use of Level 1 CALIOP products (instead of CALIOP Level 2 products in previous studies) for the detection and quantification of AAC aerosol optical depths, which leads to larger estimates of AOD above OWC; and (iii) our use of gridded 4∘×5∘ seasonal means of aerosol and cloud properties in our DAREOWC calculations instead of simultaneously derived aerosol and cloud properties from a combination of A-Train satellite sensors. Each of these areas is explored in depth with detailed discussions that explain both the rationale for our specific approach and the subsequent ramifications for our DARE calculations.

scholarly journals Estimations of Global Shortwave Direct Aerosol Radiative Effects Above Opaque Water Clouds Using a Combination of A-Train Satellite Sensors

2018 ◽  
Author(s):  
Meloë S. Kacenelenbogen ◽  
Mark A. Vaughan ◽  
Jens Redemann ◽  
Stuart A. Young ◽  
Zhaoyan Liu ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Radiative Properties ◽  
Ratio Method ◽  
Transfer Model ◽  
Radiative Effects ◽  
East Atlantic ◽  
Satellite Sensors ◽  
Aerosol Radiative Effects ◽  
532 Nm ◽  
Aerosol Radiative

Abstract. All-sky Direct Aerosol Radiative Effects (DARE) play a significant yet still uncertain role in climate. This is partly due to poorly quantified radiative properties of Aerosol Above Clouds (AAC). We compute global estimates of short-wave top-of-atmosphere DARE over Opaque Water Clouds (OWC), DAREOWC, using observation-based aerosol and cloud radiative properties from a combination of A-Train satellite sensors and a radiative transfer model. There are three major differences between our DAREOWC calculations and previous studies: (1) we use the Depolarization Ratio method (DR) on CALIOP (Cloud Aerosol LIdar with Orthogonal Polarization) Level 1 measurements to compute the AAC frequencies of occurrence and the AAC Aerosol Optical Depths (AOD), thus introducing fewer uncertainties compared to using the CALIOP standard product; (2) we apply our calculations globally, instead of focusing exclusively on regional AAC hotspots such as the southeast Atlantic; and (3) instead of the traditional look-up table approach, we use a combination of satellite-based sensors to obtain AAC intensive radiative properties. Our results agree with previous findings on the dominant locations of AAC (South and North East Pacific, Tropical and South East Atlantic, northern Indian Ocean and North West Pacific), the season of maximum occurrence, aerosol optical depths (a majority in the 0.01–0.02 range and that can exceed 0.2 at 532 nm) and aerosol extinction-to-backscatter ratios (a majority in the 40–50 sr range at 532 nm which is typical of dust aerosols) over the globe. We find positive averages of global seasonal DAREOWC between 0.13 and 0.26 W · m−2 (i.e., a warming effect on climate). Regional seasonal DAREOWC values range from −0.06 W · m−2 in the Indian Ocean, offshore from western Australia (in March–April–May) to 2.87 W · m−2 in the South East Atlantic (in September–October–November). High positive values are usually paired with high aerosol optical depths (> 0.1) and low single scattering albedos (

Aerosol radiative effects during two desert dust events in August 2012 over the Southwestern Iberian Peninsula

2015 ◽  
Vol 153 ◽  
pp. 404-415 ◽  
Author(s):  
M.A. Obregón ◽  
S. Pereira ◽  
V. Salgueiro ◽  
M.J. Costa ◽  
A.M. Silva ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Radiative Effects ◽  
Desert Dust ◽  
Dust Events ◽  
Aerosol Radiative Effects ◽  
Aerosol Radiative

Long-term changes in aerosol radiative properties at Armilla (Spain)

2004 ◽  
Vol 38 (35) ◽  
pp. 5935-5943 ◽  
Author(s):  
H. Lyamani ◽  
F.J. Olmo ◽  
L. Alados-Arboledas
Keyword(s):  
Radiative Properties ◽  
Long Term Changes ◽  
Aerosol Radiative

Aerosol Radiative Effects Over India from Direct Radiation Measurements and Model Estimates

2021 ◽  
Author(s):  
Tamanna Subba ◽  
Mukunda M. Gogoi ◽  
K. Krishna Moorthy ◽  
Pradip K. Bhuyan ◽  
Binita Pathak ◽  
...  
Keyword(s):  
Radiative Effects ◽  
Direct Radiation ◽  
Aerosol Radiative Effects ◽  
Radiation Measurements ◽  
Aerosol Radiative

scholarly journals Aerosol radiative effects with MACv2

2019 ◽  
Author(s):  
Stefan Kinne
Keyword(s):  
Anthropogenic Sources ◽  
Transfer Model ◽  
Strong Impact ◽  
Radiative Effects ◽  
Anthropogenic Aerosols ◽  
Anthropogenic Aerosol ◽  
Aerosol Forcing ◽  
Aerosol Radiative Effects ◽  
The Impact ◽  
Aerosol Radiative

Abstract. onthly global maps for aerosol properties of the MACv2 climatology are applied in an off-line radiative transfer model to determine aerosol radiative effects. For details beyond global averages in most cases global maps are presented to visualize regional and seasonal details. Aside from the direct radiative (aerosol presence) effect, including those for aerosol components as extracted from MACv2 aerosol optics, also the major aerosol indirect radiative effect is covered. Hereby, the impact of smaller drops in water clouds due to added anthropogenic aerosol was simulated by applying a satellite retrieval based fit from locally associations between aerosol and drop concentrations over oceans. Present-day anthropogenic aerosols of MACv2 – on a global average basis – reduce the radiative net-fluxes at the top of the atmosphere (TOA) by −1.0 W/m2 and at the surface by −2.1 W/m2. Direct cooling contributions are only about half of indirect contributions (−.35 vs −.65) at TOA, but about twice at the surface (−1.45 vs −.65), as solar absorption of the direct effect warms the atmosphere by +1.1 W/m2. Natural aerosols are on average less absorbing (for a relatively larger solar TOA cooling) and larger in size (now contributing with IR greenhouse warming). Thus, average TOA direct forcing efficiencies for total and anthropogenic aerosol happen to be similar: −11 W/m2/AOD at all-sky and −24 W/m2/AOD at clear-sky conditions. The present-day direct impact by all soot (BC) is globally averaged +0.55W/m2 and at least half of it should be attributed to anthropogenic sources. Hereby any accuracy of anthropogenic impacts, not just for soot, suffers from the limited access to a pre-industrial reference. Anthropogenic uncertainty has a particular strong impact on aerosol indirect effects, which dominate the (TOA) forcing. Accounting for uncertainties in the anthropogenic definition, present-day aerosol forcing is estimated to stay within the −0.7 to −1.6 W/m2 range, with a best estimate at −1 W/m2. Calculations with model predicted temporal changes to anthropogenic AOD indicate that qualitatively the anthropogenic aerosol forcing has not changed much over the last decades and is not likely to increase over the next decades, despite strong regional shifts. These regional shifts explain most solar insolation (brightening or dimming) trends that have been observed by ground-based radiation data.

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