Longwave Scattering Effects of Mineral Aerosols

Dufresne, Jean‐Louis; Gautier, Catherine; Ricchiazzi, P.; Fouquart, Y.

doi:10.1175/1520-0469(2002)059<1959:lseoma>2.0.co;2

Cited by 129 publications

(146 citation statements)

References 34 publications

(42 reference statements)

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“…Scattering of longwave radiation by mineral dust is neglected in our radiative calculations. As reported by Dufresne et al (2002), this may lead to an underestimation of longwave radiative forcing by up to 50% at TOA and 15% at the surface. It should be noted that dust optical properties are calculated in the longwave region (divided into 16 spectral bands) by using the work of Koepke et al (1997).…”

Section: Radiative Effect Parametrization and Dust Optical Propertiesmentioning

confidence: 82%

“…Dufresne et al (2002) indicate also positive surface forcings comprised between +21 and +29 W/m 2 , for six different atmospheric profiles. Finally, three dimensional modelling have been performed by Yoshioka et al (2007), who reported a mean annual value of +14 W/m 2 over the North Africa region, by using the CCSM3 model.…”

Section: Infrared Spectral Rangementioning

confidence: 88%

“…The convention used is strictly similar to the one (relation 2) used for solar wavelengths. Before presenting our results, we remind here that MesoNH simulations could underestimate the surface longwave effect by up to 15% (Dufresne et al, 2002), due to the fact that the scattering of longwave radiation is neglected.…”

Section: Infrared Spectral Rangementioning

confidence: 99%

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Impact of dust aerosols on the radiative budget, surface heat fluxes, heating rate profiles and convective activity over West Africa during March 2006

et al. 2009

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Abstract. The present work analyses the effect of dust aerosols on the surface and top of atmosphere radiative budget, surface temperature, sensible heat fluxes, atmospheric heating rate and convective activity over West Africa. The study is focused on the regional impact of a major dust event over the period of 7-14 March 2006 through numerical simulations performed with the mesoscale, nonhydrostatic atmospheric model MesoNH. Due to its importance on radiative budgets, a specific attention has been paid to the representation of dust single scattering albedo (SSA) in MesoNH by using inversions of the AErosol RObotic NETwork (AERONET). The radiative impacts are estimated using two parallel simulations, one including radiative effects of dust and the other without them. The simulations of dust aerosol impacts on the radiative budget indicate remarkable instantaneous (at midday) decrease of surface shortwave (SW) radiations over land, with regional (9 • -17 • N, 10 • W-20 • E) mean of −137 W/m 2 during the 9 to 12 March period. The surface dimming resulting from the presence of dust is shown to cause important reduction of both surface temperature (up to 4 • C) and sensible heat fluxes (up to 100 W/m 2 ), which is consistent with experimental observations. At the top of the atmosphere, the SW cooling (regional mean of

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Section: Radiative Effect Parametrization and Dust Optical Propertiesmentioning

confidence: 82%

Section: Infrared Spectral Rangementioning

confidence: 88%

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Impact of dust aerosols on the radiative budget, surface heat fluxes, heating rate profiles and convective activity over West Africa during March 2006

et al. 2009

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“…Uncertainties in the dust LW absorption coefficient are probably responsible for this difference. It should be recalled here that the LW scattering effect of mineral dust is not taken into account in CNRM-RCSM4 (Dufresne et al 2002). Figure 10 presents the semi-direct aerosol effect, resulting from calculations achieved thanks to the C-NO simulations.…”

Section: à2mentioning

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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“…In spite of more robust climate predictions in the last years, radiative forcing (RF) induced by aerosols is still the largest uncertainty to the total RF estimate (IPCC, 2014). The vertical distribution and relative location are determining factors of aerosol radiative forcing in the long-wave spectral range (Dufresne et al, 2002;Kaufman et al, 2002).…”

mentioning

confidence: 99%

An exploratory study on the aerosol height retrieval from OMI measurements of the 477  nm O<sub>2</sub> − O<sub>2</sub> spectral band using a neural network approach

et al. 2017

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Abstract. This paper presents an exploratory study on the aerosol layer height (ALH) retrieval from the OMI 477 nm O 2 −O 2 spectral band. We have developed algorithms based on the multilayer perceptron (MLP) neural network (NN) approach and applied them to 3-year (2005-2007) OMI cloudfree scenes over north-east Asia, collocated with MODIS Aqua aerosol product. In addition to the importance of aerosol altitude for climate and air quality objectives, our long-term motivation is to evaluate the possibility of retrieving ALH for potential future improvements of trace gas retrievals (e.g. NO 2 , HCHO, SO 2 ) from UV-visible air quality satellite measurements over scenes including high aerosol concentrations. This study presents a first step of this longterm objective and evaluates, from a statistic point of view, an ensemble of OMI ALH retrievals over a long time period of 3 years covering a large industrialized continental region. This ALH retrieval relies on the analysis of the O 2 −O 2 slant column density (SCD) and requires an accurate knowledge of the aerosol optical thickness, τ . Using MODIS Aqua τ (550 nm) as a prior information, absolute seasonal differences between the LIdar climatology of vertical Aerosol Structure for space-based lidar simulation (LIVAS) and average OMI ALH, over scenes with MODIS τ (550 nm) ≥ 1.0, are in the range of 260-800 m (assuming single scattering albedo ω 0 = 0.95) and 180-310 m (assuming ω 0 = 0.9).OMI ALH retrievals depend on the assumed aerosol single scattering albedo (sensitivity up to 660 m) and the chosen surface albedo (variation less than 200 m between OMLER and MODIS black-sky albedo). Scenes with τ ≤ 0.5 are expected to show too large biases due to the little impact of particles on the O 2 −O 2 SCD changes. In addition, NN algorithms also enable aerosol optical thickness retrieval by exploring the OMI reflectance in the continuum. Comparisons with collocated MODIS Aqua show agreements between −0.02 ± 0.45 and −0.18 ± 0.24, depending on the season. Improvements may be obtained from a better knowledge of the surface albedo and higher accuracy of the aerosol model. Following the previous work over ocean of Park et al. (2016), our study shows the first encouraging aerosol layer height retrieval results over land from satellite observations of the 477 nm O 2 −O 2 absorption spectral band.

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Longwave Scattering Effects of Mineral Aerosols

Cited by 129 publications

References 34 publications

Impact of dust aerosols on the radiative budget, surface heat fluxes, heating rate profiles and convective activity over West Africa during March 2006

Impact of dust aerosols on the radiative budget, surface heat fluxes, heating rate profiles and convective activity over West Africa during March 2006

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

An exploratory study on the aerosol height retrieval from OMI measurements of the 477  nm O<sub>2</sub> − O<sub>2</sub> spectral band using a neural network approach

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Longwave Scattering Effects of Mineral Aerosols

Cited by 129 publications

References 34 publications

Impact of dust aerosols on the radiative budget, surface heat fluxes, heating rate profiles and convective activity over West Africa during March 2006

Impact of dust aerosols on the radiative budget, surface heat fluxes, heating rate profiles and convective activity over West Africa during March 2006

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

An exploratory study on the aerosol height retrieval from OMI measurements of the 477 nm O&lt;sub&gt;2&lt;/sub&gt; − O&lt;sub&gt;2&lt;/sub&gt; spectral band using a neural network approach

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An exploratory study on the aerosol height retrieval from OMI measurements of the 477  nm O<sub>2</sub> − O<sub>2</sub> spectral band using a neural network approach