Measurements of Mediterranean aerosol radiative forcing and influence of the single scattering albedo

Biagio, Claudia Di; Sarra, Alcide di; Meloni, Daniela; Monteleone, Francesco; Piacentino, Salvatore; Sferlazzo, Damiano

doi:10.1029/2008jd011037

Cited by 84 publications

(113 citation statements)

References 51 publications

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“…In a more recent analysis these aerosol types are further divided in different sub-classes, depending on the observed value of the single scattering albedo, SSA (Di Biagio et al, 2009. The obtained results suggest a dependency on both the aerosol type and the SSA.…”

Section: Introductionmentioning

confidence: 83%

“…The so called direct method has been used by several authors to derive the aerosol forcing in different regions and with different aerosol components and conditions (e.g., Jayaraman et al, 1998;Conant, 2000;Podgornyi et al, 2000;Satheesh and Ramanthan, 2000;Meywerk and Ramanathan, 2002;Markowicz et al, 2002;Bush and Valero, 2002;di Sarra et al, 2008;Di Biagio et al, 2009.…”

Section: Introductionmentioning

confidence: 99%

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Estimate of surface direct radiative forcing of desert dust from atmospheric modulation of the aerosol optical depth

2013

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Measurements carried out on the island of Lampedusa, in the central Mediterranean, on 7 September 2005, show the occurrence of a quasi-periodic oscillation of aerosol optical depth, column water vapour, and surface irradiance in different spectral bands. The oscillation has a period of about 13 min and is attributed to the propagation of a gravity wave able to modify the vertical structure of the planetary boundary layer, as also confirmed by satellite images. The wave occurred during a Saharan dust event. The oscillation amplitude is about 0.1 for the aerosol optical depth, and about 0.4 cm for the column water vapour. The modulation of the downward surface irradiances is in opposition of phase with respect to aerosol optical depth and water vapour column variations. The perturbation of the downward irradiance produced by the aerosols is determined by comparing the measured irradiances with estimated irradiances at a fixed value of the aerosol optical depth, and by correcting for the effect of the water vapour in the shortwave spectral range. The direct radiative forcing efficiency, i.e., the radiative perturbation of the net surface irradiance produced by a unit of optical depth aerosol layer, is determined at different solar zenith angles as the slope of the irradiance perturbation versus the aerosol optical depth. The estimated direct surface forcing efficiency at about 60° solar zenith angle is −(181 ± 17) W m⁻² in the shortwave, and −(83 ± 7) W m⁻² in the photosynthetic spectral range. The estimated daily average forcing efficiencies are of about −79 and −46 W m⁻² for the shortwave and photosynthetic spectral range, respectively

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Section: Introductionmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Estimate of surface direct radiative forcing of desert dust from atmospheric modulation of the aerosol optical depth

2013

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“…As a first approach to estimate the compensation effect on a daily basis, the daily AFE SW has been obtained for the equinox integrating the instantaneous AFE over the 24h, taking into account the evolution of θ and time for the equinox; and assuming that AFE(90º) = 0 [1]. The daily AFE LW is difficult to obtain since it depends on variations in atmospheric structure and composition and atmospheric and surface temperatures, in addition to aerosol properties that lack during the nighttime.…”

Section: Resultsmentioning

confidence: 99%

“…The aerosol forcing efficiency (AFE) is defined as the change in the radiative forcing produced by a unit AOD at 500 nm. It can be determined as the slope of the linear regression between the DARF and the AOD at 500 nm [1,4]. This method is only applicable using a large amount of data displaying a large range of aerosol optical depths.…”

Section: Measurements and Methodologymentioning

confidence: 99%

“…Aerosol measurements in the longwave (LW) are scarce and consequently most of the knowledge about the effects in the terrestrial spectrum comes from modelling. This paper deals with the application of the direct method [1] to obtain the aerosol forcing efficiency. The method was applied to the database in the University the Valencia Station at Burjassot.…”

Section: Introductionmentioning

confidence: 99%

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Empirical determination of direct aerosol radiative effects in the shortwave and longwave spectral ranges during desert dust events over Valencia (Spain)

Gómez-Amo¹,

Utrillas²,

Martínez‐Lozano³

2013

AIP Conference Proceedings

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Abstract. Five years (2007Five years ( -2011 of aerosol optical depth and radiation measurements in Valencia (Spain) have been analysed in order to study empirically the radiative perturbation produced by the dust events to shortwave and longwave spectral ranges at the Earth surface. The direct method has been applied to only cloud free observations. The aerosol produces a surface cooling by -173 and -142 W/m 2 per unit optical depth at solar zenith angles of 20º and 50º, respectively, in the shortwave range. The shortwave cooling is partially off-set by 30-40 % by the LW heating. The LW effect can be larger (up to 60%) on a daily basis since it acts continuously also during night-time.

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Estimating aerosol characteristics from solar irradiance measurements at an urban location in southeastern Spain

Foyo-Moreno

Alados

Antón

et al. 2014

J. Geophys. Res. Atmos.

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Under cloudless conditions aerosols are the main atmospheric components responsible for direct effects on solar radiation. Measurements of aerosol optical properties along with simultaneous measurements of solar irradiances (global -G-and diffuse -D-) were recorded at an urban site (Granada, Spain) to characterize the radiative effect of atmospheric aerosols from 2006 to 2008. The selection of cloudless conditions was made considering cases with 0 oktas. To avoid cloud contamination, a restricted data set with clearness index larger than 0.65 and maximum D of 200 W/m 2 was used. The analysis was performed evaluating G, D, and I N (direct normal irradiance) and the ratios between them in association with aerosol optical depth (AOD) at 675 nm. Results show an aerosol forcing efficiency of À279 ± 21 W/m 2 per unit of AOD at 675 nm at 15°solar zenith angle and a maximum value in June for monthly mean aerosol radiative forcing of À23 ± 7 W/m 2 . Large dependency was shown of the ratios D/G and D/I N which increased with increasing AOD, while I N /G decreased. On the other hand, the ratio D/I N was the most reliable parameter to estimate AOD with a coefficient of determination of 0.94; the empirical relationship obtained was validated using an independent data set obtaining 2.5% mean bias deviation and 13.5% root-mean-square deviation. This relationship constitutes an alternative tool for estimating AOD from routine irradiance measurements available from numerous radiometric stations worldwide.

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Measurements of Mediterranean aerosol radiative forcing and influence of the single scattering albedo

Cited by 84 publications

References 51 publications

Estimate of surface direct radiative forcing of desert dust from atmospheric modulation of the aerosol optical depth

Estimate of surface direct radiative forcing of desert dust from atmospheric modulation of the aerosol optical depth

Empirical determination of direct aerosol radiative effects in the shortwave and longwave spectral ranges during desert dust events over Valencia (Spain)

Estimating aerosol characteristics from solar irradiance measurements at an urban location in southeastern Spain

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