Search results for " mine"

2021

Abstract. Sustainable aviation fuels can reduce contrail ice numbers and radiative forcing by contrail cirrus. We measured apparent ice emission indices for fuels with varying aromatic content at altitude ranges of 9.1–9.8 and 11.4–11.6 km. Measurement data were collected during the ECLIF II/NDMAX flight experiment in January 2018. The fuels varied in both aromatic quantity and type. Between a sustainable aviation fuel blend and a reference fuel Jet A-1, a maximum reduction in apparent ice emission indices of 40 % was found. We show vertical ice number and extinction distributions for three different fuels and calculate representative contrail optical depths. Optical depths of contrails (0.…

Depolarization�ratio profiling at several wavelengths in pure Saharan dust during SAMUM 2006

2009

Vertical profiles of the linear particle depolarization ratio of pure dust clouds were measured during the Saharan Mineral Dust Experiment (SAMUM) at Ouarzazate, Morocco (30.9°N, –6.9°E), close to source regions in May–June 2006, with four lidar systems at four wavelengths (355, 532, 710 and 1064 nm). The intercomparison of the lidar systems is accompanied by a discussion of the different calibration methods, including a new, advanced method, and a detailed error analysis. Over the whole SAMUM periode pure dust layers show a mean linear particle depolarization ratio at 532 nm of 0.31, in the range between 0.27 and 0.35, with a mean Ångström exponent (AE, 440–870 nm) of 0.18 (range 0.04–0.34…

Hygroscopic properties and extinction of aerosol particles at ambient relative humidity in South-Eastern China

2008

Abstract During the “Program of Regional Integrated Experiments of Air Quality over Pearl River Delta 2004 (PRIDE-PRD2004)” hygroscopic properties of particles in the diameter range 22 nm to 10 μ m were determined. For that purpose, a Humidifying Differential Mobility Particle Sizer (H-DMPS) and a Micro-Orifice Uniform Deposition Impactor (MOUDI) were operated. The derived size-dependent particle hygroscopic growth factors were interpolated to ambient relative humidity (RH) and used to calculate the particle number size distributions (PNSDs) at ambient conditions. A comparison between the modeled particle extinction coefficients ( σ ext , Mie ) and those observed with a Raman lidar was made…

2017

Abstract. Lightning represents one of the dominant emission sources for NOx in the troposphere. The direct release of oxidised nitrogen in the upper troposphere does not only affect ozone formation, but also chemical and microphysical properties of aerosol particles in this region. This study investigates the direct impact of LNOx emissions on upper-tropospheric nitrate using a global chemistry climate model. The simulation results show a substantial influence of the lightning emissions on the mixing ratios of nitrate aerosol in the upper troposphere of more than 50 %. In addition to the impact on nitrate, lightning substantially affects the oxidising capacity of the atmosphere with substan…

2012

Abstract. Mineral dust is a major fraction of global atmospheric aerosol, and the oxidation of SO2 on mineral dust has implications for cloud formation, climate and the sulfur cycle. Stable sulfur isotopes can be used to understand the different oxidation processes occurring on mineral dust. This study presents measurements of the 34S/32S fractionation factor α34 for oxidation of SO2 on mineral dust surfaces and in the aqueous phase in mineral dust leachate. Sahara dust, which accounts for ~60% of global dust emissions and loading, was used for the experiments. The fractionation factor for aqueous oxidation in dust leachate is αleachate = 0.9917±0.0046, which is in agreement with previous m…

In-situ observations of young contrails – overview and selected results from the CONCERT campaign

2010

Lineshaped contrails were detected with the research aircraft Falcon during the CONCERT – CONtrail and Cirrus ExpeRimenT – campaign in October/November 2008. The Falcon was equipped with a set of instruments to measure the particle size distribution, shape, extinction and chemical composition as well as trace gas mixing ratios of sulfur dioxide (SO<sub>2</sub>), reactive nitrogen and halogen species (NO, NO<sub>y</sub>, HNO<sub>3</sub>, HONO, HCl), ozone (O<sub>3</sub>) and carbon monoxide (CO). During 12 mission flights over Europe, numerous contrails, cirrus clouds and a volcanic aerosol layer were probed at altitudes between 8.5 and 11.6 km…

Column-integrated aerosol optical properties in Sodankylä (Finland) during the Solar Induced Fluorescence Experiment (SIFLEX-2002).

2006

[1] A study has been made of the column aerosols using solar irradiance extinction measurements at ground level in a boreal region (Sodankyla, Finland) during spring 2002. The aerosol properties have been related to air mass origin. In general, the aerosol levels were observed to be very low, independent of the air mass origin, with an aerosol optical depth (AOD) value at 500 nm of less than 0.09 ± 0.03. Two characteristic patterns were observed depending on whether the air masses originated in the north and west or from the south and east. In the first case (north and west origins) the aerosol load was very small, with very low optical depths in the range 0.03 ± 0.02 to 0.09 ± 0.03 for 500…

Extreme, wintertime Saharan dust intrusion in the Iberian Peninsula: Lidar monitoring and evaluation of dust forecast models during the February 2017…

2019

The research leading to these results has received funding from the H2020 program from the European Union (grant agreement no. 654109, 778349) and also from the Spanish Ministry of Industry, Economy and Competitiviness (MINECO, ref. CGL2013-45410-R, CGL2016-81092-R, CGL2017-85344-R, TEC2015-63832-P), the Spanish Ministry of Science, Innovation and Universities (ref. CGL2017-90884-REDT); the CommSensLab "Maria de Maeztu" Unity of Excellence (ref. MDM-2016-0600) financed by the Spanish Agencia Estatal de Investigación. Co-funding was also provided by the European Union through the European Regional Development Fund (ref. POCI-01-0145-FEDER-007690, ALT20-03-0145-FEDER-000004, ALT20-03-0145-FED…

Application of aerosol optical properties to estimate aerosol type from ground-based remote sensing observation at urban area of northeastern China

2015

Abstract Aerosol optical properties were derived from ground-based sunphotometer observations between 2009-2013 at three urban sites of Shenyang, Anshan, Fushun in northeastern China. The annual means for extinction aerosol optical depths (EAOD) at 500 nm were 0.57±0.38, 0.52±0.35, and 0.41±0.31 at Shenyang, Anshan, Fushun, respectively. The corresponding annual means for the extinction Angstrom exponents (EAE) computed for the wavelengths of 440 and 870 nm were 0.86±0.32, 0.86±0.34 and 0.91±0.35, respectively, indicating that urban area of Northeast China were affected by both coarse and fine particles. Hygroscopic growth in summer and incursions of dust aerosols in spring were evidently r…

Spectral surface albedo over Morocco and its impact on radiative forcing of Saharan dust

2011

In May–June 2006, airborne and ground-based solar (0.3–2.2 μm) and thermal infrared (4–42 μm) radiation measurements have been performed in Morocco within the Saharan Mineral Dust Experiment (SAMUM). Upwelling and downwelling solar irradiances have been measured using the Spectral Modular Airborne Radiation Measurement System (SMART)-Albedometer. With these data, the areal spectral surface albedo for typical surface types in southeastern Morocco was derived from airborne measurements for the first time. The results are compared to the surface albedo retrieved from collocated satellite measurements, and partly considerable deviations are observed. Using measured surface and atmospheric prope…