The flux of carbonyl sulfide and carbon disulfide between the atmosphere and a spruce forest

Turbulent fluxes of carbonyl sulfide (COS) and carbon disulfide (CS2) were measured over a spruce forest in Central Germany using the relaxed eddy accumulation (REA) technique. A REA sampler was developed and validated using simultaneous measurements of CO2 fluxes by REA and by eddy correlation. REA measurements were conducted during six campaigns covering spring, summer, and fall between 1997 and 1999. Both uptake and emission of COS and CS2 by the forest were observed, with deposition occurring mainly during the sunlit period and emission mainly during the dark period. On the average, however, the forest acts as a sink for both gases. The average fluxes for COS and CS2 are -93 ± 11.7 pmol m-2 s-1 and -18 ± 7.6 pmol m-2 s-1, respectively. The fluxes of both gases appear to be correlated to photosynthetically active radiation and to the CO2 and \chem{H_2O} fluxes, supporting the idea that the air-vegetation exchange of both gases is controlled by stomata. An uptake ratio COS/CO2 of 10 ± 1.7 pmol m mol-1 has been derived from the regression line for the correlation between the COS and CO2 fluxes. This uptake ratio, if representative for the global terrestrial net primary production, would correspond to a sink of 2.3 ± 0.5 Tg COS yr-1

Development of a bioaerosol single particle detector (BIO IN) for the fast ice nucleus chamber FINCH [Discussion paper]

In this work we present the setup and first tests of our new BIO IN detector. This detector is designed to classify atmospheric ice nuclei (IN) for their biological content. Biological material is identified via its auto-fluorescence (intrinsic fluorescence) after irradiation with UV radiation. Ice nuclei are key substances for precipitation development via the Bergeron–Findeisen process. The level of scientific knowledge regarding origin and climatology (temporal and spatial distribution) of IN is very low. Some biological material is known to be active as IN even at relatively high temperatures of up to –2°C (e.g. pseudomonas syringae bacteria). These biological IN could have a strong influence on the formation of clouds and precipitation. We have designed the new BIO IN sensor to analyze the abundance of IN of biological origin. The instrument will be flown on one of the first missions of the new German research aircraft ''HALO'' (High Altitude and LOng Range)

Wie in Wolken der Regen entsteht : Kristallisationskeime als Schlüssel

Wolken haben einen maßgeblichen Einfluss auf den Wasserhaushalt der Erde, das Wettergeschehen und das Klima. Sie wissenschaftlich zu beschreiben, ist schwierig – und das erschwert die Niederschlagsvorhersage ebenso wie die Klimamodellierung. Wichtig für die Entstehung von Regen in unseren Breiten sind Eispartikel. Sie machen einen großen Teil der Wolken aus. Doch wie bilden sie sich, und warum sind sie für viele physikalische Prozesse in den Wolken unentbehrlich? Und schließlich: Wirkt sich menschliches Handeln auf die Wolken aus

Hohenpeissenberg Photochemical Experiment (HOPE 2000) : measurements and photostationary state calculations of OH and peroxy radicals

Measurements of OH, total peroxy radicals, non-methane hydrocarbons (NMHCs) and various other trace gases were made at the Meteorological Observatory Hohenpeissenberg in June 2000. The data from an intensive measurement period characterised by high solar insolation (18-21 June) are analysed. The maximum midday OH concentration ranged between 4.5x106 molecules cm-3 and 7.4x106 molecules cm-3. The maximum total ROx (ROx =OH+RO+HO2+RO2) mixing ratio increased from about 55 pptv on 18 June to nearly 70 pptv on 20 and 21 June. A total of 64 NMHCs, including isoprene and monoterpenes, were measured every 1 to 6 hours. The oxidation rate of the NMHCs by OH was calculated and reached a total of over 14x106 molecules cm-3 s-1 on two days. A simple photostationary state balance model was used to simulate the ambient OH and peroxy radical concentrations with the measured data as input. This approach was able to reproduce the main features of the diurnal profiles of both OH and peroxy radicals. The balance equations were used to test the effect of the assumptions made in this model. The results proved to be most sensitive to assumptions about the impact of unmeasured volatile organic compounds (VOC), e.g. formaldehyde (HCHO), and about the partitioning between HO2 and RO2. The measured OH concentration and peroxy radical mixing ratios were reproduced well by assuming the presence of 3 ppbv HCHO as a proxy for oxygenated hydrocarbons, and a HO2/ RO2 ratio between 1:1 and 1:2. The most important source of OH, and conversely the greatest sink for peroxy radicals, was the recycling of HO2 radicals to OH. This reaction was responsible for the recycling of more than 45x106 molecules cm-3 s-1 on two days. The most important sink for OH, and the largest source of peroxy radicals, was the oxidation of NMHCs, in particular, of isoprene and the monoterpenes

Development of a Bioaerosol single particle detector (BIO IN) for the Fast Ice Nucleus CHamber FINCH

In this work we present the setup and first tests of our new BIO IN detector. This detector was constructed to classify atmospheric ice nuclei (IN) for their biological content. It is designed to be coupled to the Fast Ice Nucleus CHamber FINCH. If one particle acts as an ice nucleus, it will be at least partly covered with ice at the end of the development section of the FINCH chamber. The device combines an auto-fluorescence detector and a circular depolarization detector for simultaneous detection of biological material and discrimination between water droplets, ice crystals and non activated large aerosol particles. The excitation of biological material with UV light and analysis of auto-fluorescence is a common principle used for flow cytometry, fluorescence microscopy, spectroscopy and imaging. The detection of auto-fluorescence of airborne single particles demands some more experimental effort. However, expensive commercial sensors are available for special purposes, e.g. size distribution measurements. But these sensors will not fit the specifications needed for the FINCH IN counter (e.g. high sample flow of up 10 LPM). The newly developed -low cost- BIO IN sensor uses a single high-power UV LED for the electronic excitation instead of much more expensive UV lasers. Other key advantages of the new sensor are the low weight, compact size, and the little effect on the aerosol sample, which allows it to be coupled with other instruments for further analysis. The instrument will be flown on one of the first missions of the new German research aircraft "HALO" (High Altitude and LOng range)

The Witness of Dorothy Day and the Future of Liberation Theology

A study around the concepts of “witness” and “testimony,” in the fields of Philosophy and Theology, as exemplified by the life work of Dorothy Day. The impact of her work in the U.S., from early to mid-twentieth century, and with the Catholic Worker Movement, is compared to that of the Latin American movement of Liberation Theology. Examples are provided of Dorothy Day’s observations on the agricultural workers strike and César Chávez, as well as various socio-political movements in Latin American countries. Also detailed and compared, are the early and later efforts under Liberation Theology, for its Church influences and dictates, as well as its popular impact and significance

Wege aus der Commodity-Falle : der Product Differentiation Excellence-Ansatz

Zahlreiche Märkte sind im Begriff sich zu verändern: Die zunehmende Homogenität von Produkten, stagnierende oder sogar schrumpfende Märkte sowie eine stark zunehmende Wettbewerbsintensität führen zu einem verstärkten Preis- und Margendruck. Dieses Phänomen ist unter dem Schlagwort „Commoditisierung“ in Praxis und Wissenschaft bekannt. Ein professionelles Differenzierungsmanagement ist der zentrale Schlüssel, um die eigenen Produkte in solch einem schwierige n Marktumfeld von Konkurrenzprodukten abzuheben. Die Aufgabe ist komplex: Managern stehen zahlreiche Differenzierungsinstrumente zur Verfügung, die nur schwer zu überschauen sind. Der hier vorgestellte Product Differentiation Excellence-Ansatz (PDE) wurde als Leitfaden entwickelt, um professionell auf diese neuen Herausforderungen reagieren zu können

Back to the future with IATA NDC? Critical turning points in the history of airline distribution

Purpose - The International Air Transport Association (IATA) New Distribution Capability (NDC) standard aims at modernising the airline distribution landscape. It has supported the spread of Direct Connects by providing a common standard for linking airlines to travel agencies. The purpose of this paper is to analyse the historical development of airline distribution and to derive implications for the future. Design/methodology/approach - This paper follows the approach of Yeoman and McMahon-Beattie (2017) in providing a chronological account based on published research. Findings - Direct Connects are discussed to be a step back in the evolution of the distribution landscape because they foster disaggregation. An analysis of the history of distribution finds that a comparison of Direct Connects to the early stages of computer reservation system technology falls short to recognise the tremendous technological and market changes connected to the internet, cloud computing and the rise of low-cost carriers. Moreover, drawing on the seminal article by Anderson and Tushman (1990) on technical discontinuities and dominant designs, the current state of the distribution landscape is characterised to be an era of ferment that is driven by design competition and that might end up in a new dominant design. Originality/value - The originality of this paper lies in a critical review of the turning points of distribution. By reviewing the past developments, the paper sheds light on the contribution that IATA NDC and Direct Connect technology might deliver to the field of airline distribution

Ecclesia in América: 20 años (I)

This text is about the connection between the path of the Church of Latin America from Medellin and the Exhortation of John Paul II 31 years later, which extends the options of Medellin to all of America, North and South. We will make our reflection only on some highlights of this dense and important document, since it is impossible within the limits of this text, to cover everything. We will privilege some paragraphs and some aspects too. And this choice and selection will have to do with the context of Latin America, the south of this unique America that the Church desires united in a single vocation of fraternity.Este texto trata acerca de la conexión que hay entre el camino de la Iglesia de América Latina desde Medellín y la Exhortación de Juan Pablo II 31 años después, que extiende las opciones de Medellín a toda América, del Norte y del Sur. Haremos nuestra reflexión sólo sobre algunos puntos destacados de este documento denso e importante, ya que es imposible en los límites de este texto, cubrirlo todo. Privilegiaremos algunos párrafos y algunos aspectos también. Y esta elección y selección tendrá que ver con el contexto de América Latina, el sur de esta única América que la Iglesia desea unida en una única vocación de fraternidad

Nocturnal nitrogen oxides at a rural mountain-site in south-western Germany

A new, two-channel instrument for simultaneous NO3 and N2O5 monitoring was used to make the first comprehensive set of nocturnal NOx measurements (NO, NO2, NO3 and N2O5) at the Taunus Observatory, a rural mountain site (Kleiner Feldberg) in South-western Germany. In May 2008, NO3 and N2O5 mixing ratios were well above the instrumental detection limit (a few ppt) on all nights of the campaign and were characterised by large variability. The concentrations of NO3, N2O5 and NO2 were consistent with the equilibrium constant, K2, defining the rates of formation and thermal dissociation of N2O5. A steady-state lifetime analysis is consistent with the loss of nocturnal NOx being dominated by the reaction of NO3 with volatile organic compounds in this forested region, with N2O5 uptake to aerosols of secondary importance. Analysis of a limited dataset obtained at high relative humidity indicated that the loss of N2O5 by reaction with water vapour is less efficient (>factor 3) than derived using laboratory kinetic data. The fraction of NOx present as NO3 and N2O5 reached ~20% on some nights, with night-time losses of NOx competing with daytime losses