Biofuel blending reduces particle emissions from aircraft engines at cruise conditions.
Aviation-related aerosol emissions contribute to the formation of contrail cirrus clouds that can alter upper tropospheric radiation and water budgets, and therefore climate1. The magnitude of air-traffic-related aerosol–cloud interactions and the ways in which these interactions might change in the future remain uncertain. Modelling studies of the present and future effects of aviation on climate require detailed information about the number of aerosol particles emitted per kilogram of fuel burned and the microphysical properties of those aerosols that are relevant for cloud formation. However, previous observational data at cruise altitudes are sparse for engines burning conventional fuel…
State of mixing, shape factor, number size distribution, and hygroscopic growth of the Saharan anthropogenic and mineral dust aerosol at Tinfou, Morocco
The Saharan Mineral Dust Experiment (SAMUM) was conducted in May and June 2006 in Tinfou, Morocco. A H-TDMA system and a H-DMA-APS system were used to obtain hygroscopic properties of mineral dust particles at 85% RH. Dynamic shape factors of 1.11, 1.19 and 1.25 were determined for the volume equivalent diameters 720, 840 and 960 nm, respectively. During a dust event, the hydrophobic number fraction of 250 and 350 nm particles increased significantly from 30 and 65% to 53 and 75%, respectively, indicating that mineral dust particles can be as small as 200 nm in diameter. Log-normal functions for mineral dust number size distributions were obtained from total particle number size distributio…
The ACRIDICON-CHUVA campaign: Studying tropical deep convective clouds and precipitation over Amazonia using the new German research aircraft HALO
Abstract Between 1 September and 4 October 2014, a combined airborne and ground-based measurement campaign was conducted to study tropical deep convective clouds over the Brazilian Amazon rain forest. The new German research aircraft, High Altitude and Long Range Research Aircraft (HALO), a modified Gulfstream G550, and extensive ground-based instrumentation were deployed in and near Manaus (State of Amazonas). The campaign was part of the German–Brazilian Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems–Cloud Processes of the Main Precipitation Systems in Brazil: A Contribution to Cloud Resolving Modeling and to the GPM (Global Precipitatio…
Saharan dust absorption and refractive index from aircraft-based observations during SAMUM 2006
During the Saharan Mineral Dust Experiment (SAMUM) conducted in summer 2006 in southeast Morocco, the complex refractive index of desert dust was determined from airborne measurements of particle size distributions and aerosol absorption coefficients at three different wavelengths in the blue (467 nm), green (530 nm) and red (660 nm) spectral regions. The vertical structure of the dust layers was analysed by an airborne high spectral resolution lidar (HSRL). The origin of the investigated dust layers was estimated from trajectory analyses, combined with Meteosat 2nd Generation (MSG) scenes and wind field data analyses. The real part n of the dust refractive index was found almost constant w…
ML-CIRRUS: The Airborne Experiment on Natural Cirrus and Contrail Cirrus with the High-Altitude Long-Range Research Aircraft HALO
Abstract The Midlatitude Cirrus experiment (ML-CIRRUS) deployed the High Altitude and Long Range Research Aircraft (HALO) to obtain new insights into nucleation, life cycle, and climate impact of natural cirrus and aircraft-induced contrail cirrus. Direct observations of cirrus properties and their variability are still incomplete, currently limiting our understanding of the clouds’ impact on climate. Also, dynamical effects on clouds and feedbacks are not adequately represented in today’s weather prediction models. Here, we present the rationale, objectives, and selected scientific highlights of ML-CIRRUS using the G-550 aircraft of the German atmospheric science community. The first combi…
Regional Saharan dust modelling during the SAMUM 2006 campaign
The regional dust model system LM-MUSCAT-DES was developed in the framework of the SAMUM project. Using the unique comprehensive data set of near-source dust properties during the 2006 SAMUM field campaign, the performance of the model system is evaluated for two time periods in May and June 2006. Dust optical thicknesses, number size distributions and the position of the maximum dust extinction in the vertical profiles agree well with the observations. However, the spatio-temporal evolution of the dust plumes is not always reproduced due to inaccuracies in the dust source placement by the model. While simulated winds and dust distributions are well matched for dust events caused by dry syn…
Sensitivities of Amazonian clouds to aerosols and updraft speed
Abstract. The effects of aerosol particles and updraft speed on warm-phase cloud microphysical properties are studied in the Amazon region as part of the ACRIDICON-CHUVA experiment. Here we expand the sensitivity analysis usually found in the literature by concomitantly considering cloud evolution, putting the sensitivity quantifications into perspective in relation to in-cloud processing, and by considering the effects on droplet size distribution (DSD) shape. Our in situ aircraft measurements over the Amazon Basin cover a wide range of particle concentration and thermodynamic conditions, from the pristine regions over coastal and forested areas to the southern Amazon, which is highly poll…
Global aerosol modeling with MADE3 (v3.0) in EMAC (based on v2.53): model description and evaluation
Recently, the aerosol microphysics submodel MADE3 (Modal Aerosol Dynamics model for Europe, adapted for global applications, third generation) was introduced as a successor to MADE and MADE-in. It includes nine aerosol species and nine lognormal modes to represent aerosol particles of three different mixing states throughout the aerosol size spectrum. Here, we describe the implementation of the most recent version of MADE3 into the ECHAM/MESSy Atmospheric Chemistry (EMAC) general circulation model, including a detailed evaluation of a 10-year aerosol simulation with MADE3 as part of EMAC. We compare simulation output to station network measurements of near-surface aerosol component mass con…
The Pagami Creek smoke plume after long-range transport to the upper troposphere over Europe – aerosol properties and black carbon mixing state
Abstract. During the CONCERT 2011 field experiment with the DLR research aircraft Falcon, an enhanced aerosol layer with particle linear depolarization ratios of 6–8% at 532 nm was observed at altitudes above 10 km over northeast Germany on 16 September 2011. Dispersion simulations with HYSPILT suggest that the elevated aerosol layer originated from the Pagami Creek forest fire in Minnesota, USA, which caused pyro-convective uplift of particles and gases. The 3–4 day-old smoke plume had high total refractory black carbon (rBC) mass concentrations of 0.03–0.35 μg m−3 at standard temperature and pressure (STP) with rBC mass equivalent diameter predominantly smaller than 130 nm. Assuming a cor…
Particle chemical properties in the vertical column based on aircraft observations in the vicinity of Cape Verde Islands
During the second Saharan Mineral Dust Experiment (SAMUM-2) field campaign, particles with geometric diameters (d) between ∼0.1 and 25 μm were collected on board of the Deutsches Zentrum für Luft- und Raumfahrt (German Aerospace Center, DLR) Falcon aircraft. Size, chemical composition and mixing state of aerosols sampled (spatially and vertically resolved) along the West African coastline and in the Cape Verde Islands region were determined by electron microscopy. A pronounced layer structure of biomass-burning aerosol and desert dust was present for all days during the sampling period from 23 January to 6 February. The aerosol composition of the small particles (d < 0.5 μm) was highly v…
Size distribution, mass concentration, chemical and mineralogical composition and derived optical parameters of the boundary layer aerosol at Tinfou, Morocco, during SAMUM 2006
During the SAMUM 2006 field campaign in southern Morocco, physical and chemical properties of desert aerosols were measured. Mass concentrations ranging from 30 Ã�¼g m-3 for PM2.5 under desert background conditions up to 300,000 Ã�¼g m-3 for total suspended particles (TSP) during moderate dust storms were measured. TSP dust concentrations are correlated with the local wind speed, whereas PM10 and PM2.5 concentrations are determined by advection from distant sources. Size distributions were measured for particles between 20 nm and 500 Ã�¼m diameter (parameterizations are given). Two major regimes of the size spectrum can be distinguished. Smaller than 500 nm particle diameter, the distrib…
Solar radiative effects of a Saharan dust plume observed during SAMUM assuming spheroidal model particles
The solar optical properties of Saharan mineral dust observed during the Saharan Mineral Dust Experiment (SAMUM) were explored based on measured size-number distributions and chemical composition. The size-resolved complex refractive index of the dust was derived with real parts of 1.51–1.55 and imaginary parts of 0.0008–0.006 at 550 nm wavelength. At this spectral range a single scattering albedo ω o and an asymmetry parameter g of about 0.8 were derived. These values were largely determined by the presence of coarse particles. Backscatter coefficients and lidar ratios calculated with Mie theory (spherical particles) were not found to be in agreement with independently measured lidar data.…
Airborne measurements of dust layer properties, particle size distribution and mixing state of Saharan dust during SAMUM 2006
The Saharan Mineral Dust Experiment (SAMUM) was conducted in May/June 2006 in southern Morocco. As part of SAMUM, airborne in situ measurements of the particle size distribution in the diameter range 4 nm < Dp < 100 μm were conducted. The aerosol mixing state was determined below Dp < 2.5 μm. Furthermore, the vertical structure of the dust layers was investigated with a nadir-looking high spectral resolution lidar (HSRL). The desert dust aerosol exhibited two size regimes of different mixing states: below 0.5 μm, the particles had a non-volatile core and a volatile coating; larger particles above 0.5 μm consisted of non-volatile components and contained light absorbing material. In…