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- ItemPollution events observed during CARIBIC flights in the upper troposphere between South China and the Philippines(München : European Geopyhsical Union, 2010) Lai, S.C.; Baker, A.K.; Schuck, T.J.; van Velthoven, P.; Oram, D.E.; Zahn, A.; Hermann, M.; Weigelt, A.; Slemr, F.; Brenninkmeijer, C.A.M.; Ziereis, H.A strong pollution episode in the upper troposphere between South China and the Philippines was observed during CARIBIC flights in April 2007. Five pollution events were observed, where enhancements in aerosol and trace gas concentrations including CO, CO2, CH4, non-methane hydrocarbons (NMHCs) and halocarbons were observed along the flight tracks during four sequential flights. The importance of the contribution of biomass/biofuel burning was investigated using chemical tracers, emission factor analysis, back-trajectory analysis and satellite images. The Indochinese peninsula was identified as the probable source region of biomass/biofuel burning. However, enhancements in the urban/industrial tracer C2Cl4 during the events also indicate a substantial contribution from urban anthropogenic emissions. An estimation of the contribution of fossil fuel versus biomass/biofuel to the CO enhancement was made, indicating a biomass/biofuel burning contribution of ~54 to ~92% of the observed CO enhancements. Biomass/biofuel burning was found to be the most important source category during the sampling period.
- ItemOrigin of aerosol particles in the mid-latitude and subtropical upper troposphere and lowermost stratosphere from cluster analysis of CARIBIC data(München : European Geopyhsical Union, 2009) Köppe, M.; Hermann, M.; Brenninkmeijer, C.A.M.; Heintzenberg, J.; Schlager, H.; Schuck, T.; Slemr, F.; Sprung, D.; van Velthoven, P.F.J.; Wiedensohler, A.; Zahn, A.; Ziereis, H.The origin of aerosol particles in the upper troposphere and lowermost stratosphere over the Eurasian continent was investigated by applying cluster analysis methods to in situ measured data. Number concentrations of submicrometer aerosol particles and trace gas mixing ratios derived by the CARIBIC (Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrument Container) measurement system on flights between Germany and South-East Asia were used for this analysis. Four cluster analysis methods were applied to a test data set and their capability of separating the data points into scientifically reasonable clusters was assessed. The best method was applied to seasonal data subsets for summer and winter resulting in five cluster or air mass types: stratosphere, tropopause, free troposphere, high clouds, and boundary layer influenced. Other source clusters, like aircraft emissions could not be resolved in the present data set with the used methods. While the cluster separation works satisfactory well for the summer data, in winter interpretation is more difficult, which is attributed to either different vertical transport pathways or different chemical lifetimes in both seasons. The geographical distribution of the clusters together with histograms for nucleation and Aitken mode particles within each cluster are presented. Aitken mode particle number concentrations show a clear vertical gradient with the lowest values in the lowermost stratosphere (750–2820 particles/cm3 STP, minimum of the two 25% – and maximum of the two 75%-percentiles of both seasons) and the highest values for the boundary-layer-influenced air (4290–22 760 particles/cm3 STP). Nucleation mode particles are also highest in the boundary-layer-influenced air (1260–29 500 particles/cm3 STP), but are lowest in the free troposphere (0–450 particles/cm3 STP). The given submicrometer particle number concentrations represent the first large-scale seasonal data sets for the upper troposphere and lowermost stratosphere over the Eurasian continent.
- ItemGaseous mercury distribution in the upper troposphere and lower stratosphere observed onboard the CARIBIC passenger aircraft(München : European Geopyhsical Union, 2009) Slemr, F.; Ebinghaus, R.; Brenninkmeijer, C.A.M.; Hermann, M.; Kock, H.H.; Martinsson, B.G.; Schuck, T.; Sprung, D.; van Velthoven, P.; Zahn, A.; Ziereis, H.Total gaseous mercury (TGM) was measured onboard a passenger aircraft during monthly CARIBIC flights (Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrumented Container) made between May 2005 and March 2007 on the routes Frankfurt–São Paulo–Santiago de Chile and back and Frankfurt–Guangzhou–Manila and back. The data provide for the first time an insight into the seasonal distributions of TGM in the upper troposphere and lower stratosphere (UT/LS) of both hemispheres and demonstrate the importance of mercury emissions from biomass burning in the Southern Hemisphere. Numerous plumes were observed in the upper troposphere, the larger of which could be characterized in terms of Hg/CO emission ratios and their probable origins. During the flights to China TGM correlated with CO in the upper troposphere with a seasonally dependent slope reflecting the longer lifetime of elemental mercury when compared to that of CO. A pronounced depletion of TGM was always observed in the extratropical lowermost stratosphere. TGM concentrations there were found to decrease with the increasing concentrations of particles. Combined with the large concentrations of particle bond mercury in the stratosphere observed by others, this finding suggests either a direct conversion of TGM to particle bound mercury or an indirect conversion via a semivolatile bivalent mercury compound. Based on concurrent measurements of SF6 during two flights, the rate of this conversion is estimated to 0.4 ng m−3 yr−1. A zero TGM concentration was not observed during some 200 flight hours in the lowermost stratosphere suggesting an equilibrium between the gaseous and particulate mercury.
- ItemCivil Aircraft for the regular investigation of the atmosphere based on an instrumented container: The new CARIBIC system(München : European Geopyhsical Union, 2007) Brenninkmeijer, C.A.M.; Crutzen, P.; Boumard, F.; Dauer, T.; Dix, B.; Ebinghaus, R.; Filippi, D.; Fischer, H.; Franke, H.; Frieß, U.; Heintzenberg, J.; Helleis, F.; Hermann, M.; Kock, H.H.; Koeppel, C.; Lelieveld, J.; Leuenberger, M.; Martinsson, B.G.; Miemczyk, S.; Moret, H.P.; Nguyen, H.N.; Nyfeler, P.; Oram, D.; O'Sullivan, D.; Penkett, S.; Platt, U.; Pupek, M.; Ramonet, M.; Randa, B.; Reichelt, M.; Rhee, T.S.; Rohwer, J.; Rosenfeld, K.; Scharffe, D.; Schlager, H.; Schumann, U.; Slemr, F.; Sprung, D.; Stock, P.; Thaler, R.; Valentino, F.; van Velthoven, P.; Waibel, A.; Wandel, A.; Waschitschek, K.; Wiedensohler, A.; Xueref-Remy, I.; Zahn, A.; Zech, U.; Ziereis, H.An airfreight container with automated instruments for measurement of atmospheric gases and trace compounds was operated on a monthly basis onboard a Boeing 767-300 ER of LTU International Airways during long-distance flights from 1997 to 2002 (CARIBIC, Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrument Container, http://www.caribic-atmospheric.com). Subsequently a more advanced system has been developed, using a larger capacity container with additional equipment and an improved inlet system. CARIBIC phase #2 was implemented on a new long-range aircraft type Airbus A340-600 of the Lufthansa German Airlines (Star Alliance) in December 2004, creating a powerful flying observatory. The instrument package comprises detectors for the measurement of O3, total and gaseous H2O, NO and NOy, CO, CO2, O2, Hg, and number concentrations of sub-micrometer particles (>4 nm, >12 nm, and >18 nm diameter). Furthermore, an optical particle counter (OPC) and a proton transfer mass spectrometer (PTR-MS) are incorporated. Aerosol samples are collected for analysis of elemental composition and particle morphology after flight. Air samples are taken in glass containers for laboratory analyses of hydrocarbons, halocarbons and greenhouse gases (including isotopic composition of CO2) in several laboratories. Absorption tubes collect oxygenated volatile organic compounds. Three differential optical absorption spectrometers (DOAS) with their telescopes mounted in the inlet system measure atmospheric trace gases such as BrO, HONO, and NO2. A video camera mounted in the inlet provides information about clouds along the flight track. The flying observatory, its equipment and examples of measurement results are reported.
- ItemSubmicrometer aerosol particle distributions in the upper troposphere over the mid-latitude North Atlantic - Results from the third route of 'CARIBIC'(Milton Park : Taylor & Francis, 2017) Hermann, M.; Brenninkmeijer, C.A.M.; Slemr, F.; Heintzenberg, J.; Martinsson, B.G.; Schlager, H.; Van Velthoven, P.F.J.; Wiedensohler, A.; Zahn, A.; Ziereis, H.Particle number and mass concentrations of submicrometer aerosol particles were determined for the upper troposphere over the mid-latitude North Atlantic within the Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrument Container project (CARIBIC, http://www.caribic-atmospheric.com). Between May 2001 and April 2002, 22 flights from Germany to the Caribbean were conducted using an automated measurement container on a B767 passenger aircraft. Spatial and seasonal probability distributions for ultrafine and Aitken mode particles as well as mass concentrations of particulate sulphur in 8–12 km altitude are presented. High particle number concentrations (mostly 2500–15 000 particles cm-3 STP) are particularly found in summer over the western North Atlantic Ocean close to the North American continent. The distributions together with an analysis of particle source processes show that deep vertical transport is the dominant process leading to most of the events with high particle number concentrations (8000 particles cm-3 STP) for ultrafine particles as well as for Aitken mode particles. This study emphasizes the importance of deep vertical transport and cloud processing for the concentration of aerosol particles in the upper troposphere.