Tellus B 01/2011; 63:430–447. · 4.38 Impact Factor
ABSTRACT: The biogeochemical cycle of mineral dust is of major interest to understand climatic changes. Moreover, these particles can also cause risks for human health and societal activities in regions in the neighbourhoods of arid and semi-arid source areas of dust emission. To estimate and forecast atmospheric dust concentrations and their impacts, the correct description of the spatial and temporal variability of dust emission occurrences and intensities is a prerequisite. The explicit dust emission models provide a physical description of the main processes involved in dust production. They allow describing the spatio-temporal variability of the non-linear phenomenon of dust production if their input parameters (surface and soil features, surface winds) are accurately described. The recent developments, the current limits of these emission models, and some of their applications using relevant surface, soil and meteorological databases to simulate dust emissions are presented here.
IOP Conference Series Earth and Environmental Science 04/2009; 7(1):012006.
ABSTRACT: We observed a long-range transport event of mineral dust from North Africa to South Europe during the Saharan Mineral Dust Experiment (SAMUM) 2006. Geometrical and optical properties of that dust plume were determined with Sun photometer of the Aerosol Robotic Network (AERONET) and Raman lidar near the North African source region, and with Sun photometers of AERONET and lidars of the European Aerosol Research Lidar Network (EARLINET) in the far field in Europe. Extinction-to-backscatter ratios of the dust plume over Morocco and Southern Europe do not differ. Ångström exponents increase with distance from Morocco. We simulated the transport, and geometrical and optical properties of the dust plume with a dust transport model. The model results and the experimental data show similar times regarding the appearance of the dust plume over each EARLINET site. Dust optical depth from the model agrees in most cases to particle optical depth measured with the Sun photometers. The vertical distribution of the mineral dust could be satisfactorily reproduced, if we use as benchmark the extinction profiles measured with lidar. In some cases we find differences. We assume that insufficient vertical resolution of the dust plume in the model calculations is one reason for these deviations.
Tellus B 01/2009; 61(1):325 - 339. · 4.38 Impact Factor
ABSTRACT: The ash plume of the Icelandic volcano Eyjafjallajökull covering Europe in April and May 2010 has notably attracted the interest of atmospheric researchers. Emission, transport, and deposition of the volcanic ash are simulated with the regional chemistry-transport model COSMOeMUSCAT. Key input parameters for transport models are the ash injection height, which controls the ash layer height during
long-range transport, and the initial particle size distribution, which influences the sedimentation velocity. For each model layer, relative release rates are parameterised using stereo-derived plume heights from NASA’s space-borne Multi-angle Imaging SpectroRadiometer (MISR) observations near the
source. With this model setup the ash is emitted at several levels beneath the maximum plume heights
reported by the Volcanic Ash Advisory Centre (VAAC) London. The initial particle size distribution used in COSMOeMUSCAT is derived from airborne in-situ measurements. In addition, the impact of different injection heights on the vertical distribution of the volcanic ash plume over Europe is shown. Ash emissions at specific control levels allow to assess the relative contribution of each layer to the spatial
distribution after transport. The model results are compared to aerosol optical depths from European Sun photometer sites, lidar profiles measured over Leipzig/Germany, and ground-based microphysical measurements from several German air quality stations. In particular the good agreement between modelled vertical profiles of volcanic ash and lidar observations indicates that using the MISR stereoheight
retrievals to characterize atmospheric ash input provide an alternative to injection height models in case of lacking information on eruption dynamics.
Atmospheric Environment. online(2012-48):195-204.
ABSTRACT: The spatio-temporal evolution of the Saharan dust and biomass-burning plume during the SAMUM-2 field campaign
in January and February 2008 is simulated at 28 km horizontal resolution with the regional model-system COSMOMUSCAT.
The model performance is thoroughly tested using routine ground-based and space-borne remote sensing
and local field measurements. Good agreement with the observations is found in many cases regarding transport
patterns, aerosol optical thicknesses and the ratio of dust to smoke aerosol. The model also captures major features
of the complex aerosol layering. Nevertheless, discrepancies in the modelled aerosol distribution occur, which are
analysed in detail. The dry synoptic dynamics controlling dust uplift and transport during the dry season are well
described by the model, but surface wind peaks associated with the breakdown of nocturnal low-level jets are not
always reproduced. Thus, a strong dust outbreak is underestimated. While dust emission modelling is a priori more
challenging, since strength and placement of dust sources depend on on-line computed winds, considerable inaccuracies
also arise in observation-based estimates of biomass-burning emissions. They are caused by cloud and spatial errors of
satellite fire products and uncertainties in fire emission parameters, and can lead to unrealistic model results of smoke
Tellus B - Chemical and Physical Meteorology. 63B(2011):781-799.