Aerosol elemental concentrations in the tropopause region from intercontinental flights with the Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrument Container (CARIBIC) platform

Abstract

This study with the Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrument Container (CARIBIC) platform investigates the aerosol elemental concentrations at 9–11 km altitude in the northern hemisphere. Measurements from 31 intercontinental flights over a 2‐year period between Germany and Sri Lanka/Maldives in the Indian Ocean are presented. Aerosol samples were collected with an impaction technique and were analyzed for the concentration of 18 elements using particle‐induced X‐ray emission (PIXE). Additional measurements of particle number concentrations, ozone and carbon monoxide concentrations, and meteorological modeling were included in the interpretation of the aerosol elemental concentrations. Particulate sulphur was found to be by far the most abundant element. Its upper tropospheric concentration increased, on average, by a factor of 2 from the tropics to midlatitudes, with another factor 2 higher concentrations in the lowermost stratosphere over midlatitudes. Correlation patterns and source profiles suggest contributions from crustal sources and biomass burning, but not from meteor ablation. Coinciding latitudinal gradients in particulate sulphur concentrations and emissions suggest that fossil fuel combustion is an important source of the aerosol in the upper troposphere and lowermost stratosphere. The measurements indicate aerosol transport along isentropic surfaces across the tropopause into the lowermost stratosphere. As a result of the prolonged residence time, ageing via oxidation of sulphur dioxide in the lowermost stratosphere was found to be a likely high‐altitude, strong source that, along with downward transport of stratospheric air, could explain the vertical gradient of particulate sulphur mass concentration around the extratropical tropopause.

Comparison between CARIBIC Aerosol Samples Analysed by Accelerator-Based Methods and Optical Particle Counter Measurements

“…Minor constituents were detected less frequently, like for instance potassium (K) 41 %, iron (Fe) 44 % and nickel (Ni) 30 %. The accuracy of the analyses is estimated to 10 % (Papaspiropoulos et al, 2002;Nguyen and Martinsson, 2007).…”

“…Black carbon constitutes a small fraction of the total carbon (Schwarz et al, 2010;Friberg et al, 2014). Occasionally chemical elements connected with crustal matter and fires are observed (Papaspiropoulos et al, 2002), which on rare occasions can have a strong influence on aerosol particle concentration (Eguchi et al, 2009;Dirksen et al, 2009;Fromm et al, 2010). Particles from explosive volcanism have strong effects on the studied region at times, affecting the climate (Ammann et al, 2003;Solomon et al, 2011), stratospheric ozone (McCormick et al, 1995) and aviation (Gislason et al, 2011).…”

Civil Aircraft for the regular investigation of the atmosphere based on an instrumented container: The new CARIBIC system

“…Because of the limited range of the aircraft only a limited number of flights into the southern hemisphere (in this case South Africa) could be made. The data set has so far provided a basis for studies of aerosol particle elemental composition, formation and climatology of aerosols in the tropopause region Hermann et al, 2003;Martinsson et al, 2001;Papaspiropoulos et al, 2002), the interpretation of tropospheric O 3 and CO correlations, as well as their correlation in respect to transport across the tropopause and chemical processing (Zahn et al, 2000(Zahn et al, , 2002a(Zahn et al, , 2004aZahn and Brenninkmeijer, 2003), and for process studies (Mühle et al, 2002;Zahn et al, 2002b). The data have also contributed to studies of trace gas cycles in the atmosphere (Krol et al, 2003;Sturges et al, 2000) and enabled studies of the isotopic composition of CO including 14 CO (Joeckel, 2000) as a global tracer for OH, and of H 2 and its D/H ratio for constraining budget calculations for the atmospheric H 2 budget (Rhee et al, 2006).…”

“…4.7 below). 4.7 Aerosol particle sampling and analysis Aerosol particle collection proved very valuable during the first phase of CARIBIC (Martinsson et al, 2001;Papaspiropoulos et al, 2002;Martinsson et al, 2005). Presently a new multi-channel impactor sampler (Nguyen et al, 2006) collects particle samples for quantitative elemental analysis by Particle-Induced X-ray Emission (PIXE) (Papaspiropoulos et al, 1999) and Particle Elastic Scattering Analyses (PESA) (Nguyen and Martinsson, 2007).…”

Composition and evolution of volcanic aerosol from eruptions of Kasatochi, Sarychev and Eyjafjallajökull in 2008–2010 based on CARIBIC observations

“…Martinsson et al (2009) found that volcanic aerosol contains a large carbonaceous component. Additional sources contributing to the aerosol load in the UT/LMS, include air traffic (Ferry et al, 1999;Kjellström et al, 1999), meteorites (Cziczo et al, 2001) and boundary layer aerosol and precursor gases transported across the tropopause (Papaspiropoulos et al, 2002;Köppe et al, 2009). Especially aerosol from forest fires can be brought to high altitudes by extreme convection, however, the frequency and global contribution of such events is poorly understood (Fromm et al, 2004(Fromm et al, , 2008.…”