The direct effect of aerosols on solar radiation over the broader Mediterranean basin

Papadimas, C. D.; Hatzianastassiou, N.; Matsoukas, C.; Kanakidou, Maria; Mihalopoulos, N.; Vardavas, I.

doi:10.5194/acp-12-7165-2012

Cited by 111 publications

(100 citation statements)

References 91 publications

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“…Such a reverse of DRE TOA sign has been also reported in previous studies (e.g. Santese et al, 2010;Nabat et al, 2012;Papadimas et al, 2012). Over highly reflective surfaces (i.e.…”

Section: Geographical Distributionssupporting

confidence: 51%

“…Gkikas et al: Direct radiative effects during intense Mediterranean desert dust outbreaks the perturbations of the radiation fields are determined to a large extent by AOD (e.g. Hatzianastassiou et al, 2004;Pérez et al, 2006;Papadimas et al, 2012). Nevertheless, several factors affect or determine the level of agreement between observed and simulated AODs, providing a reasonable explanation for the discrepancies found between MODIS and NMMB-MONARCH.…”

Section: Comparison Of Model and Satellite Aodsmentioning

confidence: 99%

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Direct radiative effects during intense Mediterranean desert dust outbreaks

et al. 2018

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Abstract. The direct radiative effect (DRE) during 20 intense and widespread dust outbreaks, which affected the broader Mediterranean basin over the period March 2000-February 2013, has been calculated with the NMMB-MONARCH model at regional (Sahara and European continent) and shortterm temporal (84 h) scales. According to model simulations, the maximum dust aerosol optical depths (AODs) range from ∼ 2.5 to ∼ 5.5 among the identified cases. At midday, dust outbreaks locally induce a NET (shortwave plus longwave) strong atmospheric warming (DRE ATM values up to 285 W m −2 ; Niger-Chad; dust AODs up to ∼ 5.5) and a strong surface cooling (DRE NETSURF values down to −337 W m −2 ), whereas they strongly reduce the downward radiation at the ground level (DRE SURF values down to −589 W m −2 over the Eastern Mediterranean, for extremely high dust AODs, 4.5-5). During night-time, reverse effects of smaller magnitude are found. At the top of the atmosphere (TOA), positive (planetary warming) DREs up to 85 W m −2 are found over highly reflective surfaces (Niger-Chad; dust AODs up to ∼ 5.5) while negative (planetary cooling) DREs down to −184 W m −2 (Eastern Mediterranean; dust AODs 4.5-5) are computed over dark surfaces at noon. Dust outbreaks significantly affect the mean regional radiation budget, with NET DREs ranging from −8.5 to 0.5 W m −2 , from −31.6 to 2.1 W m −2 , from −22.2 to 2.2 W m −2 and from −1.7 to 20.4 W m −2 for TOA, SURF, NETSURF and ATM, respectively. Although the shortwave DREs are larger than the longwave ones, the latter are comparable or even larger at TOA, particularly over the Sahara at midday. As a response to the strong surface day-time cooling, dust outbreaks cause a reduction in the regional sensible and latent heat fluxes by up to 45 and 4 W m −2 , respectively, averaged over land areas of the simulation domain. Dust outbreaks reduce the temperature at 2 m by up to 4 K during day-time, whereas a reverse tendency of similar magnitude is found during nighttime. Depending on the vertical distribution of dust loads and time, mineral particles heat (cool) the atmosphere by up to 0.9 K (0.8 K) during day-time (night-time) within atmospheric dust layers. Beneath and above the dust clouds, mineral particles cool (warm) the atmosphere by up to 1.3 K (1.2 K) at noon (night-time). On a regional mean basis, negative feedbacks on the total emitted dust (reduced by 19.5 %) and dust AOD (reduced by 6.9 %) are found when dust interacts with the radiation. Through the consideration of dust radiative effects in numerical simulations, the model positive and negative biases for the downward surface SW or LW radiation, respectively, with respect to Baseline Surface Radiation Network (BSRN) measurements, are reduced. In addition, they also reduce the model near-surface (at 2 m) nocturnal cold biases by up to 0.5 K (regional averages), as well as the model warm biases at 950 and 700 hPa, where the dust concentration is maximized, by up to 0.4 K. However, improvements are relatively small and do not happen in all ...

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“…Such a reverse of DRE TOA sign has been also reported in previous studies (e.g. Santese et al, 2010;Nabat et al, 2012;Papadimas et al, 2012). Over highly reflective surfaces (i.e.…”

Section: Geographical Distributionssupporting

confidence: 51%

Section: Comparison Of Model and Satellite Aodsmentioning

confidence: 99%

Direct radiative effects during intense Mediterranean desert dust outbreaks

et al. 2018

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“…These two elements lead to an enhanced absorption of reflected radiation, hence a positive TOA SW DRF in summer (?0.8 Wm -2 ). Compared to values from Papadimas et al (2012) and RegCM in table 2 over the broader Mediterranean basin, C-AER TOA forcing is higher, especially over Europe and the Mediterranean Sea, which is probably due to differences in surface albedo.…”

Section: à2mentioning

confidence: 92%

“…However the seasonal cycle of dust particles notably is similar with a maximum in spring and summer. In addition to RCM estimations, Papadimas et al (2012) have also calculated the surface SW radiative effect over the broader Mediterranean basin (29-46.5°N, 10.5°W-38.5°E) over the period 2000-2007 using MODIS observations. Their results are compared in the last two columns of Table 2 against the averages for-C-AER over the same box: results are close to the C-AER simulation at the surface with a slight overestimation by C-AER (À19:9 Wm À2 on average for CNRM-RCSM4 against -16.5 Wm -2 ).…”

Section: Aerosol Variabilitymentioning

confidence: 99%

Direct and semi-direct aerosol radiative effect on the Mediterranean climate variability using a coupled regional climate system model

et al. 2014

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A fully coupled regional climate system model (CNRM-RCSM4) has been used over the Mediterranean region to investigate the direct and semi-direct effects of aerosols, but also their role in the radiation-atmosphereocean interactions through multi-annual ensemble simulations (2003)(2004)(2005)(2006)(2007)(2008)(2009)) with and without aerosols and oceanatmosphere coupling. Aerosols have been taken into account in CNRM-RCSM4 through realistic interannual monthly AOD climatologies. An evaluation of the model has been achieved, against various observations for meteorological parameters, and has shown the ability of CNRM-RCSM4 to reproduce the main patterns of the Mediterranean climate despite some biases in sea surface temperature (SST), radiation and cloud cover. The results concerning the aerosol radiative effects show a negative surface forcing on average because of the absorption and scattering of the incident radiation. The SW surface direct effect is on average -20.9 Wm -2 over the Mediterranean Sea, -14.7 Wm -2 over Europe and -19.7 Wm -2 over northern Africa. The LW surface direct effect is weaker as only dust aerosols contribute (?4.8 Wm -2 over northern Africa). This direct effect is partly counterbalanced by a positive semi-direct radiative effect over the Mediterranean Sea (?5.7 Wm -2 on average) and Europe (?5.0 Wm -2 ) due to changes in cloud cover and atmospheric circulation. The total aerosol effect is consequently negative at the surface and responsible for a decrease in land (on average -0.4°C over Europe, and -0.5°C over northern Africa) and sea surface temperature (on average -0.5°C for the Mediterranean SST). In addition, the latent heat loss is shown to be weaker (-11.0 Wm -2 ) in the presence of aerosols, resulting in a decrease in specific humidity in the lower troposphere, and a reduction in cloud cover and precipitation. Simulations also indicate that dust aerosols warm the troposphere by absorbing solar radiation, and prevent radiation from reaching the surface, thus stabilizing the troposphere. The comparison with the model response in atmosphere-only simulations shows that these feedbacks are attenuated if SST cannot be modified by aerosols, highlighting the importance of using coupled regional models over the Mediterranean. Oceanic convection is also strengthened by aerosols, which tends to reinforce the Mediterranean thermohaline circulation. In parallel, two case studies are presented to illustrate positive feedbacks between dust aerosols and regional climate. First, the eastern Mediterranean was subject to high dust aerosol loads in June 2007 which reduce land and sea surface temperature, as well as air-sea humidity fluxes. Because of northern wind over the eastern Mediterranean, drier and cooler air has been consequently advected from the sea to the African continent, reinforcing the direct dust effect over land. On the contrary, during the western European heat wave in June 2006, dust aerosols have contributed to reinforcing an important ridge responsible for dry and 123Cl...

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“…Generally, modelling tools and observations indicate that anthropogenic aerosols have had a cooling influence on Earth since preindustrial time. The main mechanisms affecting the radiative budget are the solar radiation scattering and absorption of aerosols (direct effect); and the cloud and precipitation alteration, affecting both the radiation and the hydrology (called indirect effect) (Papadimas et al, 2012). Scattering aerosols increase the brightness of the planet, producing cooling forcing, with the same order of magnitude as aerosols affecting reflectivity of clouds.…”

Section: Introductionmentioning

confidence: 99%

Estudio de modelización on-line del efecto directo de los aerosoles atmosféricos sobre Europa

2016

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Atmospheric aerosols affect human health, ecosystems, materials, visibility and Earth's climate. Those effects are studied in this present work and depend mainly on the aerosol optical properties and how they influence the Earth's radiation budget. Such properties can be divided on direct and semi-direct effect, produced by the scattering and absorption of radiation; and indirect effect, which influences the aerosols-cloud interactions. The aim of this work is to assess the direct effect through the study of the mean temperature; the radiation that reaches the Earth's surface and at the top of the atmosphere; and the interaction of these meteorological variables with particulate matter (PM 10 ). Results indicate decreases in temperature and radiation that reaches the Earth's surface, together with increases in the outgoing radiation at top of the atmosphere, and changes in the particulate matter, thus proving a colder climate due to the direct effect of atmospheric aerosols. Key words: Aerosol, optical properties, scattering, absorption, Earth's radiation budget, direct, semidirect and indirect effect.Estudio de modelización on-line del efecto directo de los aerosoles atmosféricos sobre Europa ResumenLos aerosoles atmosféricos provocan efectos sobre la salud humana, los ecosistemas, los materiales, la visibilidad y el clima terrestre. Estos últimos efectos son objetos de estudio en el presente trabajo y dependen, principalmente, de las propiedades ópticas de los aerosoles y como éstas influyen en el balance radiativo terrestre. Dichos efectos se pueden dividir en efecto directo y semi-directo, producidos por la dispersión y absorción de la radiación; y efecto indirecto, en el que los aerosoles interaccionan con las nubes. El objetivo principal de este trabajo es evaluar el efecto directo mediante el estudio de las variables medias de temperatura; radiación que llega a la superficie de la Tierra y que sale del tope de la atmósfera; y la interacción de estas variables meteorológicas con la materia particulada (PM 10 ). Los resultados indican descensos en la temperatura y la radiación que llega a la superficie de la Tierra, aumentos en la radiación que sale del tope de la atmósfera y variaciones en la materia particulada, resultando así en un enfriamiento del clima debido al efecto directo de los aerosoles atmosféricos. Palabras clave: Aeorosol, propiedades ópticas, dispersión, absorción, balance radiativo terrestre, efecto directo, semi-directo e indirecto.

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The direct effect of aerosols on solar radiation over the broader Mediterranean basin

Cited by 111 publications

References 91 publications

Direct radiative effects during intense Mediterranean desert dust outbreaks

Direct radiative effects during intense Mediterranean desert dust outbreaks

Direct and semi-direct aerosol radiative effect on the Mediterranean climate variability using a coupled regional climate system model

Estudio de modelización on-line del efecto directo de los aerosoles atmosféricos sobre Europa

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