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- Papaspiropoulos, Giorgos, et al.
(författare)
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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
- 2002
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Ingår i: Journal of Geophysical Research: Atmospheres. - 2169-897X. ; 107:D23
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Tidskriftsartikel (refereegranskat)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.
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| 2. |
- Heintzenberg, J, et al.
(författare)
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Number and sulfur derived 3-parameter aerosol size distributions in the tropopause region from CARIBIC flights between Germany and the Indic
- 2002
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Ingår i: Journal of Aerosol Science. - 0021-8502. ; 33:4, s. 595-608
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Tidskriftsartikel (refereegranskat)abstract
- Aerosol number concentrations in three size ranges (d(p) > 4, d(p) > 12, 18 less than or equal to, dp less than or equal to, 135 nm) and sulfur mass from impactor samples were collected over a total of about 120 sampling hours on 18 long-range commercial flights between the northern mid-latitudes and the equatorial region covering an altitude range between 8.8 and 11.2 km. The data were evaluated with a new random search algorithm to derive monomodal lognormal particle size distributions. Through tests of the algorithm using synthetic data and size distributions from mountain stations the retrieval capabilities of the fitting algorithm are established. The fitting of aerosol data yields three parameters of the submicrometer size distribution. Their latitudinal trends indicate the influence of tropical and mid-latitudinal source regions on the tropopause aerosol. Total particle numbers show maxima near tropical biomass burning, and over the European regions. Geometric mean diameters decrease north of 35degreesN while the width of the distribution increases, indicating a move towards more frequent recent nucleation events or more frequent bimodal size distributions. (C) 2002 Elsevier Science Ltd. All rights reserved.
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