Optimized approach to retrieve information on the tropospheric and stratospheric carbonyl sulfide (OCS) vertical distributions above Jungfraujoch from high-resolution FTIR solar spectra

Carbonyl sulfide (OCS), which is produced in the troposphere from both biogenic and anthropogenic sources, is the most abundant gaseous sulfur species in the unpolluted atmosphere. Due to its low chemical reactivity and water solubility, a significant fraction of OCS is able to reach the stratosphere where it is converted to SO2 and ultimately to H2SO4 aerosols (Junge layer). These aerosols have the potential to amplify stratospheric ozone destruction on a global scale and may influence Earth’s radiation budget and climate through increasing solar scattering. The transport of OCS from troposphere to stratosphere is thought to be the primary mechanism by which the Junge layer is sustained during nonvolcanic periods. Because of this, long-term trends in atmospheric OCS concentration, not only in the troposphere but also in the stratosphere, are of great interest. A new approach has been developed and optimized to retrieve atmospheric abundance of OCS from high-resolution ground-based infrared solar spectra by using the SFIT-2 (v3.91) algorithm, including a new model for solar lines simulation (solar lines often produce significant interferences in the OCS microwindows). The strongest lines of the nu3 fundamental band of OCS at 2062 cm-1 have been systematically evaluated with objective criteria to select a new set of microwindows, assuming the HITRAN 2004 spectroscopic parameters with an increase in the OCS line intensities of the nu3band main isotopologue 16O12C32S by 15.79% as compared to HITRAN 2000 (Rothman et al., 2008, and references therein). Two regularization schemes have further been compared (deducted from ATMOS and ACE-FTS measurements or based on a Tikhonov approach), in order to select the one which optimizes the information content while minimizing the error budget. The selected approach has allowed us to determine updated OCS long-term trend from 1988 to 2009 in both the troposphere and the stratosphere, using spectra recorded on a regular basis with Fourier Transform Infrared spectrometers (FTIRs), under clear-sky conditions, at the NDACC site (Network for the Detection of Atmospheric Composition Change, visit http://www.ndacc.org) of the International Scientific Station of the Jungfraujoch (Swiss Alps, 46.5°N, 8.0°E, 3580m asl). Trends and seasonal cycles deduced from our results will be compared to values published in the literature and critically discussed. In particular, we will confirm the recent change in the OCS total column trend, which has become positive since 2002 before undergoing a slowing down over the last years

Changes in atmospheric composition discerned from long-term NDACC measurements: trends in direct greenhouse gases derived from infrared solar absorption spectra recorded at the Jungfraujoch station

The University of Liège (ULg) is operating -under clear sky conditions- two state-of-the-art Fourier Transform Infrared (FTIR) spectrometers at the high-altitude research station of the Jungfraujoch (Swiss Alps, 46.5ºN, 3580m asl), within the framework of the Network for the Detection of Atmospheric Composition Changes (NDACC). Routine FTIR operation started in 1984. Since then, it has been continued without disruption, allowing collecting more than 45000 high-resolution broadband IR solar absorption spectra, between 2 and 16 µm, using either HgCdTe or InSb detectors as well as a suite of optical filters. Typically, the spectral resolutions achieved lie in the 0.003 to 0.009 cm-1 interval while signal-to-noise ratios of 1000 and more are reached. Numerous narrow-band IR spectra essentially recorded from 1976 to 1989 with grating instruments are also available. Their analyses with modern tools have recently started [Bader et al., 2011] and will be pursued to consistently extend our datasets back in the 1970s. Geophysical parameters are deduced from the ULg observational database either with the SFIT-1, SFIT-2 or PROFFIT-9 algorithm, allowing producing total column time series of the target gases. In addition, information on their vertical distributions with altitude can generally be derived when using SFIT-2 or PROFFIT-9 which both implement the Optimal Estimation Method of Rodgers [1990]. Presently, more than two dozen atmospheric species are systematically retrieved from the Jungfraujoch observations, allowing the monitoring of key constituents of the Earth's atmosphere which play important roles in stratospheric ozone depletion and/or in global warming. This communication will focus on the direct and major greenhouse gases available from our database, namely water vapor, CO2, CH4, N2O, tropospheric ozone, CFC-11, CFC-12, HCFC-22, CCl4, SF6, as well as CF4 which has recently been added to our targets list [Duchatelet et al., 2011]. Trends and associated uncertainties characterizing the available -and often multi-decadal- time series have been derived or updated with a statistical bootstrap resampling tool [Gardiner et al., 2008], they will be presented and critically compared with data available from the literature

Une lettre de Panait Istrati à Jean Guéhenno

Duchatelet Bernard. Une lettre de Panait Istrati à Jean Guéhenno . In: Littératures 17, automne 1987. pp. 181-190

Jean-François Millet. Un ouvrage de Romain Rolland inédit en français

Duchatelet Bernard. Jean-François Millet. Un ouvrage de Romain Rolland inédit en français. In: Annales de Bretagne. Tome 76, numéro 2-3, 1969. pp. 541-583

Powiedziane i przemilczane w listach Romain Rollanda

Czytając korespondencję, którą prowadzili Romain Rolland i Roger Martin du Gard znajdujemy przemilczenia dające się wyjaśnić jedynie informacjami zawartymi w listach do osób trzecich lub w Dzienniku pisarza. Zjawisko to występuje również w innych zbiorach listów autora Jana Krzysztofa. Wydaje się zatem, że kiedy przystępujemy do wydawania korespondencji, należy do publikowanych listów dodać wszystkie dokumenty, które - rzucając na nie dodatkowe światło - nadają im wymiar prawdy

La genèse de Jean-Christophe. I : La préparation (1886-1903)

Duchatelet Bernard. La genèse de Jean-Christophe. I : La préparation (1886-1903). In: Annales de Bretagne. Tome 80, numéro 3-4, 1973. pp. 573-599

Powiedziane i przemilczane w listach Romain Rollanda

Czytając korespondencję, którą prowadzili Romain Rolland i Roger Martin du Gard znajdujemy przemilczenia dające się wyjaśnić jedynie informacjami zawartymi w listach do osób trzecich lub w Dzienniku pisarza. Zjawisko to występuje również w innych zbiorach listów autora Jana Krzysztofa. Wydaje się zatem, że kiedy przystępujemy do wydawania korespondencji, należy do publikowanych listów dodać wszystkie dokumenty, które - rzucając na nie dodatkowe światło - nadają im wymiar prawdy

Jean-Christophe, syndicaliste ?

Duchatelet Bernard. Jean-Christophe, syndicaliste ?. In: Annales de Bretagne et des pays de l'Ouest. Tome 85, numéro 3, 1978. pp. 439-447

Le second journal des années de guerre de Romain Rolland

Lors de la publication, en 1937, d’extraits de son Journal des années de guerre 1914-1919, Romain Rolland les fit précéder d’un « Avertissement » où il donnait quelques précisions sur la forme de ce Journal : Je tiens, depuis ma jeunesse, un Journal, – sans idée aucune de le publier. Quand on doit, comme j’ai dû, pendant un demi-siècle, marcher à peu près seul, c’est un besoin vital de se faire son rapport de marche régulier et d’inscrire le tracé du chemin parcouru pour mieux assurer ses pa..

Antoinette est-elle Henriette ?

Duchatelet Bernard. Antoinette est-elle Henriette ?. In: Études Renaniennes, N°71, 1er trimestre 1988. pp. 27-31