A new Saharan dust source activation frequency map derived from MSG‐SEVIRI IR‐channels

Schepanski, Kerstin; Tegen, Ina; Bouchet, L.; Heinold, Bernd; Macke, Andreas

doi:10.1029/2007gl030168

Cited by 310 publications

(434 citation statements)

References 24 publications

(37 reference statements)

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“…This may have a significant impact on satellite retrievals over the desert, such as the SEVIRI-RGB thermal infrared dust product , which has been used to infer dust source regions (Schepanski et al, 2007;Ashpole and Washington, 2012) and can be used as preferential dust source regions in models Heinold et al, 2011) and for dust model evaluation . The abundance of large particles may have implications for other satellite retrievals over desert surfaces which make assumptions on dust size and/or optical properties.…”

Section: Discussionmentioning

confidence: 99%

Optical properties of Saharan dust aerosol and contribution from the coarse mode as measured during the Fennec 2011 aircraft campaign

et al. 2013

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Abstract. New in-situ aircraft measurements of Saharan dust originating from Mali, Mauritania and Algeria taken during the Fennec 2011 aircraft campaign over a remote part of the Sahara Desert are presented. Size distributions extending to 300 µm are shown, representing measurements extending further into the coarse mode than previously published for airborne Saharan dust. A significant coarse mode was present in the size distribution measurements with effective diameter (d eff ) from 2.3 to 19.4 µm and coarse mode volume median diameter (d vc ) from 5.8 to 45.3 µm. The mean size distribution had a larger relative proportion of coarse mode particles than previous aircraft measurements. The largest particles (with d eff > 12 µm, or d vc > 25 µm) were only encountered within 1 km of the ground. Number concentration, mass loading and extinction coefficient showed inverse relationships to dust age since uplift. Dust particle size showed a weak exponential relationship to dust age. Two cases of freshly uplifted dust showed quite different characteristics of size distribution and number concentration.Single Scattering Albed (SSA) values at 550 nm calculated from the measured size distributions revealed high absorption ranging from 0.70 to 0.97 depending on the refractive index. SSA was found to be strongly related to d eff . New instrumentation revealed that direct measurements, behind Rosemount inlets, overestimate SSA by up to 0.11 when d eff is greater than 2 µm. This is caused by aircraft inlet inefficiencies and sampling losses. Previous measurements of SSA from aircraft measurements may also have been overestimates for this reason. Radiative transfer calculations indicate that the range of SSAs during Fennec 2011 can lead to underestimates in shortwave atmospheric heating rates by 2.0 to 3.0 times if the coarse mode is neglected. This will have an impact on Saharan atmospheric dynamics and circulation, which should be taken into account by numerical weather prediction and climate models.

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Section: Discussionmentioning

confidence: 99%

Optical properties of Saharan dust aerosol and contribution from the coarse mode as measured during the Fennec 2011 aircraft campaign

et al. 2013

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“…The use of satellite data to constrain emissions (e.g. through the use of preferential source areas) has allowed significant improvement in the identification of source regions (e.g., Prospero et al, 2002;Schepanski et al, 2007) and the agreement of models with observed optical depths . However in order to simulate the various feedbacks on dust production that may be influenced by climate change, more of the basic production processes will need to be represented explicitly in models.…”

Section: Summary and Status Of Dust In Earth System Modelsmentioning

confidence: 99%

A review of natural aerosol interactions and feedbacks within the Earth system

et al. 2010

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Abstract.The natural environment is a major source of atmospheric aerosols, including dust, secondary organic material from terrestrial biogenic emissions, carbonaceous particles from wildfires, and sulphate from marine phytoplankton dimethyl sulphide emissions. These aerosols also have a significant effect on many components of the Earth system such as the atmospheric radiative balance and photosynthetically available radiation entering the biosphere, the supply of nutrients to the ocean, and the albedo of snow and ice. The physical and biological systems that produce these aerosols can be highly susceptible to modification due to climate change so there is the potential for important climate feedbacks. We review the impact of these natural systems on atmospheric aerosol based on observations and models, including the potential for long term changes in emissions and the feedbacks on climate. The number of drivers of change is very large and the various systems are strongly coupled. There have therefore been very few studies that integrate the various effects to estimate climate feedback factors. Nevertheless, available observations and model studies suggest that the regional radiative perturbations are potentially several Watts per square metre due to changes in these natural aerosol emissions in a future climate. Taking into account only the direct radiative effect of changes in the atmospheric burden of natural aerosols, and neglecting potentially large effects on other parts of the Earth system, a global mean radiative perturbation approaching 1 W m −2 is possible by the end of the century. The level of scientific understanding of the climate drivers, interactions and impacts is very low.

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“…The satellite is located at 3.5 • W over the equator and has a horizontal resolution of 3 km at nadir and a time resolution of 15 min. The dust index is composed of the BTD at 12.0-10.8 µm and at 10.8-8.7 µm, as well as of the BT at 10.8 µm (Schepanski et al, 2007). It is based on the same BTs as EUMETSAT's dust index product of MSG scenes offered on its website (http://www.eumetsat.int).…”

Section: Satellite Imagesmentioning

confidence: 99%

A case of extreme particulate matter concentrations over Central Europe caused by dust emitted over the southern Ukraine

et al. 2008

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Abstract. On 24 March 2007, an extraordinary dust plume was observed in the Central European troposphere. Satellite observations revealed its origins in a dust storm in Southern Ukraine, where large amounts of soil were resuspended from dried-out farmlands at wind gusts up to 30 m s−1. Along the pathway of the plume, maximum particulate matter (PM10) mass concentrations between 200 and 1400 μg m−3 occurred in Slovakia, the Czech Republic, Poland, and Germany. Over Germany, the dust plume was characterised by a volume extinction coefficient up to 400 Mm−1 and a particle optical depth of 0.71 at wavelength 0.532 μm. In-situ size distribution measurements as well as the wavelength dependence of light extinction from lidar and Sun photometer measurements confirmed the presence of a coarse particle mode with diameters around 2–3 μm. Chemical particle analyses suggested a fraction of 75% crustal material in daily average PM10 and up to 85% in the coarser fraction PM10–2.5. Based on the particle characteristics as well as a lack of increased CO and CO2 levels, a significant impact of biomass burning was ruled out. The reasons for the high particle concentrations in the dust plume were twofold: First, dust was transported very rapidly into Central Europe in a boundary layer jet under dry conditions. Second, the dust plume was confined to a relatively stable boundary layer of 1.4–1.8 km height, and could therefore neither expand nor dilute efficiently. Our findings illustrate the capacity of combined in situ and remote sensing measurements to characterise large-scale dust plumes with a variety of aerosol parameters. Although such plumes from Southern Eurasia seem to occur rather infrequently in Central Europe, its unexpected features highlights the need to improve the description of dust emission, transport and transformation processes needs, particularly when facing the possible effects of further anthropogenic desertification and climate change.

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A new Saharan dust source activation frequency map derived from MSG‐SEVIRI IR‐channels

Cited by 310 publications

References 24 publications

Optical properties of Saharan dust aerosol and contribution from the coarse mode as measured during the Fennec 2011 aircraft campaign

Optical properties of Saharan dust aerosol and contribution from the coarse mode as measured during the Fennec 2011 aircraft campaign

A review of natural aerosol interactions and feedbacks within the Earth system

A case of extreme particulate matter concentrations over Central Europe caused by dust emitted over the southern Ukraine

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