Nonmethane hydrocarbon and halocarbon distributions during Atlantic Stratocumulus Transition Experiment/Marine Aerosol and Gas Exchange, June 1992

Aircraft measurements of selected nonmethane hydrocarbon and halocarbon species were made in the lower troposphere of the NE Atlantic near the Azores, Portugal, during June 1992 as part of the Atlantic Stratocumulus Transition Experiment/Marine Aerosol and Gas Exchange. In this paper, the impact of continental outflow from both Europe and North America on the study region were assessed. Four main air mass types were characterized from trajectories and trace gas concentrations: clean marine from the Atlantic, and continental air from the Iberian Peninsula, the British Isles and Northern Europe, and North America. Each classification exhibited trace gas concentrations that had been modified en route by photochemical processes and mixing. Comparison with the clean marine boundary layer (MBL) shows that the boundary layer of the predominantly continental air masses were enhanced in hydrocarbons and halocarbons by factors of approximately 2 for ethane, 5 for propane, 2-6 for ethyne and benzene, and 2-3 for C2Cl4. The same air masses also exhibited large ozone enhancements, with 2 to 3 times higher mixing ratios in the continental boundary layer air compared to the clean MBL. This indicates a primarily anthropogenic photochemical source for a significant fraction of the lower tropospheric ozone in this region. Methyl bromide exhibited on average 10-20% higher concentrations in the boundary layer affected by continental outflow than in the clean MBL, and was seen to be enhanced in individual plumes of air of continental origin. This is consistent with significant anthropogenic sources for methyl bromide. In addition, median MBL concentrations of ethene and methyl iodide showed enhancements of approximately a factor of 2 above free tropospheric values, suggesting primarily coastal/oceanic sources for these species. Copyright 1996 by the American Geophysical Union

Hydrocarbon and halocarbon measurements as photochemical and dynamical indicators of atmospheric hydroxyl, atomic chlorine, and vertical mixing obtained during Lagrangian flights

Nonmethane hydrocarbons and halocarbons were measured during two Lagrangian experiments conducted in the lower troposphere of the North Atlantic as part of the June 1992, Atlantic Stratosphere Transition Experiment/Marine Aerosol and Gas Exchange (ASTEX/MAGE) expedition. The first experiment was performed in very clean marine air. Meteorological observations indicate that the height of the marine boundary layer rose rapidly, entraining free tropospheric air. However, the free tropospheric and marine boundary layer halocarbon concentrations were too similar to allow this entrainment to be quantified by these measurements. The second Lagrangian experiment took place along the concentration gradient of an aged continental air mass advecting from Europe. The trace gas measurements confirm that the National Center for Atmospheric Research (NCAR) Electra aircraft successfully intercepted the same air mass on consecutive days. Two layers, a surface layer and a mixed layer with chemically distinct compositions, were present within the marine boundary layer. The composition of the free troposphere was very different from that of the mixed layer, making entrainment from the free troposphere evident Concentrations of the nonmethane hydrocarbons in the Lagrangian surface layer were observed to become depleted relative to the longer-lived tetrachloroethene. A best fit to the observations was calculated using various combinations of the three parameters, loss by reaction with hydroxyl, loss by reaction with chlorine, and/or dilution from the mixed layer. These calculations provided estimated average concentrations in the surface layer for a 5-hour period from dawn to 11 UT of 0.3±0.5 ×106 molecules cm-3 for HO, and 3.3±;1.1 ×104 molecules cm-3 for Cl. Noontime concentration estimates were 2.6±0.7 ×106 molecules cm-3 for HO and 6.5±1.4 ×104 molecules cm-3 for Cl. Copyright 1996 by the American Geophysical Union

Three-dimensional distribution of nonmenthane hydrocarbons and halocarbons over the northwestern Pacific during the 1991 Pacific Exploratory Mission (PEM-West A)

A total of 1667 whole air samples were collected onboard the NASA DC-8 aircraft during the 6-week Pacific Exploratory Mission over the western Pacific (PEM-West A) in September and October 1991. The samples were assayed for 15 C2-C7 hydrocarbons and six halocarbons. Latitudinal (0.5°S to 59.5°N) and longitudinal (114°E to 122°W) profiles were obtained from samples collected between ground level and 12.7 km. Thirteen of the 18 missions exhibited at least one vertical profile where the hydrocarbon mixing ratios increased with altitude. Longitude-latitude color patch plots at three altitude levels and three-dimensional color latitudealtitude and longitude-altitude contour plots exhibit a significant number of middle-upper tropospheric pollution events. These and several lower tropospheric pollution plumes were characterized by comparison with urban data from Tokyo and Hong Kong, as well as with natural gas and the products from incomplete combustion. Elevated levels of nonmethane hydrocarbons (NMHC) and other trace gases in the upper-middle free troposphere were attributed to deep convection over the Asian continent and to typhoon-driven convection near the western Pacific coast of Asia. In addition, NMHCs and CH3CCI3 were found to be useful tracers with which to distinguish hydrocarbon and halocarbon augmented plumes emitted from coastal Asian cities into the northwestern Pacific

Scribal Crusading: Three New Manuscript Witnesses to the Regional Reception and Transmission of First Crusade Letters

The First Crusade is one of the most intensively researched events of the Middle Ages, yet, paradoxically, the manuscript source base for the letters from the expedition is almost entirely unexplored and represents an exciting new avenue of investigation for crusade studies. This article publishes the texts of three new manuscript witnesses of First Crusade letters and explores their regional reception and transmission as a form of “scribal crusading” – that is, monastic participation in the crusades from behind cloister walls. The findings of this article reveal an extremely significant, but previously underappreciated, collective impulse among German monastic communities in the twelfth and thirteenth centuries to participate in the crusading movement through the copying of First Crusade letters

First Crusade Letters and Medieval Monastic Scribal Cultures

The letters of the First Crusade have traditionally been read as authentic and trustworthy eyewitness accounts of the expedition and they contribute greatly to scholarly understanding of the campaign. But new research on them demonstrates that many of the documents are in fact twelfth-century confections produced in the monastic communities of the West as a means of supporting, participating in and engaging with the crusading movement. This article develops new approaches to the letters and new research questions which account for and accept the problematic authenticity of the corpus, pivoting away from traditional methodologies to explore the monastic scribal cultures that produced and consumed First Crusade letters

How to craft a crusade call: Pope Innocent III and Quia maior (1213)

The fame of Quia maior – commonly considered one of the most important medieval papal crusade encyclicals – belies the fact that we actually know little about its composition at the curia of Pope Innocent III in 1213. This article compares a lesser‐known draft of the letter, Quoniam maior, preserved in the chronicle of Burchard of Ursberg, with Quia maior in order to reconstruct the debates and concerns of its authors during the composition process. It seeks to advance our understanding of Innocent’s conception of the crusade and offers new insights into how the papacy crafted crusade calls in the Middle Ages

The First Crusade Letter Written at Laodicea in 1099: Two Previously Unpublished Versions from Munich, Bayerische Staatsbibliothek Clm 23390 and 28195

This article analyses the author’s discovery in Munich, Bayerische Staatsbibliothek Clm 23390 of a fourth recension of the letter written by the leaders of the First Crusade at Laodicea in September 1099 (Hagenmeyer no. XVIII). A different version of the same letter from the second recension, unearthed in Clm 28195 by Benjamin Kedar in the 1980s, is also analysed and both letters are published for the first time. It is argued that these copies of the letter testify to flourishing interest in the crusading movement in the monastic houses of southern Germany and Austria in the period between the Third Crusade and the Crusade of Frederick II. The letters were probably copied as part of a celebration and commemoration of German participation in the crusades, which culminated in the recovery of Jerusalem by Frederick II in 1229. The present article also contends that greater attention should be given to the regional manuscript traditions of the letters of the First Crusade, so as to reveal more about their popularity and transmission in the Middle Ages

Counting cell number in situ by quantification of dimethyl sulphide in culture headspace.

A novel, non-invasive technique is reported for determining the numbers of cells in a culture by quantifying dimethyl sulphide (DMS) in the culture headspace as produced by the cellular enzymatic reduction of dissolved dimethyl sulphoxide (DMSO). Measured DMS concentrations, as performed using selected ion flow tube mass spectrometry (SIFT-MS), in the headspace of 2D and 3D cultures of four cell lines, viz. HEK293 (kidney), MG63 (bone), hepG2 (liver) and CALU-1 (lung), linearly correlate with starting cell number. Clear differences in the rates of production of DMS by the four cell types in both the 2D and 3D situations are seen. This novel analytical technique for cell enumeration offers a significant contribution to quality assessment across cell-based research and industry, including analysis of large scale culture systems, and for routine cell biology research