References of "Mahieu, Emmanuel"
     in
Bookmark and Share    
Full Text
See detailRetrievals of HCN from high-resolution FTIR solar spectra recorded at the Jungfraujoch station
Mahieu, Emmanuel ULg; Duchatelet, Pierre ULg; Demoulin, Philippe ULg et al

in Geophysical Research Abstracts (2007, April)

Recent investigations have resulted in the revision of the lifetime of hydrogen cyanide (HCN) from 2.5 years to 2-5 months, more in line with its important and well documented variability in the ... [more ▼]

Recent investigations have resulted in the revision of the lifetime of hydrogen cyanide (HCN) from 2.5 years to 2-5 months, more in line with its important and well documented variability in the troposphere. The main HCN source is believed to be biomass burning, making this species a useful tracer of fires, e.g. the widespread and intense 2004 boreal fires. Oxidation by the OH radical is among the identified sinks, while uptake by oceans has been hypothesized as the dominant sink. As shown by previous investigations, several lines from the nu3 fundamental HCN band at 3 μm can be used to retrieve information on vertical distribution of hydrogen cyanide from high-resolution FTIR solar absorption spectra. The major interfering gas in this region is water vapor. A series of typical observations recorded at the Jungfraujoch station (46.5ºN, 8.0ºE, 3580m asl, Swiss Alps) by the NDACC (Network for the Detection of Atmospheric Composition Change)-affiliated Bruker instrument have been fitted using various approaches to determine the optimum strategy to be used for HCN retrievals at that site, even under very wet conditions. The selected approach is made of 7 windows encompassing 5 HCN lines. The a priori information (HCN vertical distribution and covariance matrix) is based on ACE-FTS measurements performed over northern midlatitudes. The HITRAN-2004 spectroscopic line parameters including the August 2006 updates for water vapor have been adopted in the retrievals performed with the OEM-SFIT-2 (v3.91) algorithm. This contribution will give a full description of the adopted retrieval approach, including error budget and information content analysis. Tropospheric column time series of HCN from 1994 onwards will also be presented and discussed. [less ▲]

Detailed reference viewed: 63 (6 ULg)
Full Text
See detailMeasured and modelled trends of stratopsheric Cly and Fy column amounts in the northern hemisphere
Ruhnke, Roland; Blumenstock, Thomas; Duchatelet, Pierre ULg et al

Poster (2007, April)

Reactive inorganic chlorine plays a crucial role in the stratospheric ozone depletion. To stabilize and enable a recovering of the stratospheric ozone layer, the Montreal protocol and its amendments and ... [more ▼]

Reactive inorganic chlorine plays a crucial role in the stratospheric ozone depletion. To stabilize and enable a recovering of the stratospheric ozone layer, the Montreal protocol and its amendments and adjustments have been progressively implemented to reduce or even stop the production and emission of important chlorinated source gases (CFCs, HCFCs, CCl4, CH3CCl3, and Halons). As these source gases are photolysed in the stratosphere into inorganic chlorine and fluorine, respectively, the turn over of the inorganic chlorine (HCl and ClONO2) and slowing down of fluorine (HF and COF2) reservoirs act as a verification of the effectiveness of these protocols. Here we present results of long-term measurements of the stratospheric column of HCl, ClONO2, and HF obtained at different stations in the northern hemisphere (Ny Alesund, Kiruna, Zugspitze, Jungfraujoch, Izana, all affiliated to the NDACC, Network for the Detection of Atmospheric Composition Change) within the PEP (Pole- Equator-Pole) network. These time series are interpreted with model calculations performed with a state of the art 2-D model and the 3-D CTM KASIMA with respect to the determination of the slowing down or turn over, respectively. In addition, trend parameters calculated using different approaches (e.g. linear trend, bootstrap-method) will be presented and intercompared. [less ▲]

Detailed reference viewed: 30 (5 ULg)
Full Text
See detailApproaches for retrieving abundances of methane isotopologues in the frame of the AGACC project from ground-based FTIR observations performed at the Jungfraujoch
Duchatelet, Pierre ULg; Mahieu, Emmanuel ULg; Demoulin, Philippe ULg et al

Poster (2007, April)

This work has been performed within the frame of AGACC(http://www.oma.be/AGACC/Home.html), a contribution to the Belgian Scientific Support for a Sustainable Development. The project intends to make an ... [more ▼]

This work has been performed within the frame of AGACC(http://www.oma.be/AGACC/Home.html), a contribution to the Belgian Scientific Support for a Sustainable Development. The project intends to make an advanced exploitation of existing ground-based remote-sensing measurements for a selection of atmospheric species that play an important role in the chemistry of the atmosphere and that have a direct or indirect impact on climate. Target species include -among others- lower tropospheric aerosols, H2O, HDO, CH4, HCN and CO. The instrumentation includes 3 types of spectrometers (FTIR, MAXDOAS and Brewer) and one CIMEL sun photometer. These instruments are operated at 3 different sites (Jungfraujoch, Ile de la Réunion and Uccle) and most of them are affiliated with the Network for the Detection of Atmospheric Composition Change (NDACC, formerly NDSC - http://www.ndacc.org), a group dedicated to performing high-quality long-term observations. This contribution will deal with the detection of the isotopologues of methane, a species released to the atmosphere by natural processes (e.g. wetlands, termites) as well as by anthropogenic activities (e.g. fossil fuel exploitation, rice agriculture, biomass burning, etc). Due to its high warming potential and its relatively long chemical lifetime, atmospheric methane is a major greenhouse gas. Methane also affects climate by influencing tropospheric ozone and stratospheric water. The cycle of methane is complex and a thoroughly study of the sources and sinks of its main isotopologue, as well as the other isotopic species, is necessary to characterize it. Isotopic ratios are also useful to differentiate between various sources of atmospheric methane. To study the vertical distribution of methane isotopologues from the high resolution FTIR spectra recorded by the University of Liège instrument at the International Scientific Station of the Jungfraujoch (ISSJ; 46.5°N, 8.0°E, 3580m a.s.l., Swiss Alps), we have selected several 13CH4 lines distributed in the so-called InSb (1-5 µm) and MCT (2-16 µm) spectral ranges. A set of four microwindows has also been selected for the study of CH3D. Using the SFIT-2 v3.91 algorithm, vertical column abundances as well as low-resolution vertical distributions have been retrieved, adjusted from an a priori profile defined on a 41 layers scheme and derived from ACE-FTS space observations. The information content and first preliminary retrieval results will be presented. [less ▲]

Detailed reference viewed: 130 (1 ULg)
Full Text
See detailDetermination of COF2 vertical distributions above Jungfraujoch by FTIR and multi-spectra fitting
Duchatelet, Pierre ULg; Mahieu, Emmanuel ULg; Demoulin, Philippe ULg et al

Poster (2007, April)

The major sources of fluorine in the stratosphere are CFC-11 and CFC-12. Photolysis of these compounds leads to release of chlorine atoms, while the fluorine is, in a first step, present in the form of ... [more ▼]

The major sources of fluorine in the stratosphere are CFC-11 and CFC-12. Photolysis of these compounds leads to release of chlorine atoms, while the fluorine is, in a first step, present in the form of carbonyl compounds like COClF and COF2. Their further photolysis liberates fluorine atoms, which are quickly converted to HF. Given its long life time, COF2 is the second stratospheric fluorine reservoir. The first COF2 vertical distributions were derived from occultation measurements performed by the ATMOS instrument during the SPACELAB-3 Space Shuttle mission in 1985. The Canadian FTIR spectrometer ACE-FTS, onboard the SCISAT-1 satellite, is the first instrument since the last ATMOS flight in 1994, to record COF2 vertical profiles from space. All these observations show that, at mean latitudes, COF2 concentration is maximum between 30 and 35 km. Several COF2 IR absorption lines located either in the so-called InSb (1-5 µm) and MCT (2-16 µm) spectral ranges can be used to determine its total column from ground-based FTIR observations. In this context, several studies concerning the evolution of COF2 total column above various stations were published during the nineties. At this time, no study concerning the inversion of COF2 vertical distributions from ground-based FTIR spectra has been published. This report deals with the feasibility of such inversions, using, simultaneously, via the SFIT-2 v3.91 algorithm, a multi-microwindows and a multi-spectra fitting procedure. The multi-spectra method consists of combining several FTIR observations, recorded during the same day, to increase the information content. A selection of microwindows in InSb and MCT ranges, a complete discussion about the data characterization (e.g. information content) and typical examples of COF2 retrieved profiles from high resolution solar spectra recorded with the University of Liège Jungfraujoch FTS will be revealed. [less ▲]

Detailed reference viewed: 49 (7 ULg)
Full Text
See detailLong-lived organic compounds (Chapter 1)
Clerbaux, C.; Cunnold, D. M.; Anderson, J. et al

in Nohende Ajavon, Ayité-Lô; Albritton, Daniel L.; Watson, Robert T. (Eds.) Scientific Assessment of Ozone Depletion: 2006 (2007)

This assessment report is a summary of the scientific community's current understanding of the stratospheric ozone layer and its relation to humankind.

Detailed reference viewed: 22 (4 ULg)
Full Text
Peer Reviewed
See detailLong-term trends of tropospheric carbon monoxide and hydrogen cyanide from analysis of high resolution infrared solar spectra
Rinsland, Curtis P.; Goldman, Aaron; Hannigan, James W. et al

in Journal of Quantitative Spectroscopy & Radiative Transfer (2007), 104(1), 40-51

Long-term trend and seasonal variation of the mean free tropospheric volume mixing ratios of carbon monoxide (CO) and hydrogen cyanide (HCN) have been derived from analysis of a time series of solar ... [more ▼]

Long-term trend and seasonal variation of the mean free tropospheric volume mixing ratios of carbon monoxide (CO) and hydrogen cyanide (HCN) have been derived from analysis of a time series of solar absorption spectra recorded from the US National Solar Observatory on Kitt Peak (31.9 degrees N, 111.6 degrees W, 2.09 km altitude) spanning almost three decades. The results of a fit to the CO 258 daily averages from May 1977 to April 2005 as a function of time with a model that assumes a sinusoidal seasonal cycle and a linear long-term trend with time yield a mean volume mixing ratio of 102 +/- 3) parts per billion (10(-9) per unit volume) below 10km altitude, I sigma. The CO measurements show a seasonal cycle with a maximum in March and a minimum in September with an amplitude of (22.3 +/- 1.5)% relative to the mean. The best-fit corresponds to a long-term CO trend of (0.15 +/- 0.14)% yr(-1), 1 sigma, relative to the mean. To quantify the possible impact of periods of intense fires, the CO measurements have been compared with the measurements of HCN, a well-documented emission product of biomass burning with a lifetime of similar to 5 months. The best fit to the full HCN time series of 208 daily averages from May 1978 to April 2005 results in a mean volume mixing ratio of (0.219 +/- 0.007) ppbv below 10 km altitude with a similar seasonal cycle, though with a lower relative amplitude than for CO. Although same-day enhancements up to a factor of 1.87 for HCN and 1.24 for CO were measured relative to values predicted by a fit to the time series that accounts for the seasonal cycles and trends of both molecules, excluding time periods of elevated fire emissions has no significant impact on the best-fit long-term free tropospheric CO and HCN trends. Our result of no long-term CO trend since the late 1970s suggests that the global average long-term decline reported from 1990 through 1995 measurements has not continued in the free troposphere. Similarly, a fit to the full time series of 208 HCN free tropospheric daily averages with the same model yields an average 2.09-10km mixing ratio of 0.219ppbv and a long-term trend of (-0.12 +/- 0.14) % yr(-1), 1 sigma, relative to the mean since 1978, also indicating no significant long-term trend above the lower mid-latitude continental US Kitt Peak station. The results for both molecules suggest the site was not significantly impacted by summer boreal fires during the time span of the measurements that in some years cause widespread pollution above northern higher latitude sites. (c) 2006 Elsevier Ltd. All rights reserved. [less ▲]

Detailed reference viewed: 46 (9 ULg)
Full Text
Peer Reviewed
See detailComparisons between ground-based FTIR and MIPAS N2O and HNO3 profiles before and after assimilation in BASCOE
Vigouroux, Corinne; De Mazière, Martine; Errera, Quentin et al

in Atmospheric Chemistry and Physics (2007), 7

Within the framework of the Network for Detection of Atmospheric Composition Change (NDACC), regular ground-based Fourier transform infrared ( FTIR) measurements of many species are performed at several ... [more ▼]

Within the framework of the Network for Detection of Atmospheric Composition Change (NDACC), regular ground-based Fourier transform infrared ( FTIR) measurements of many species are performed at several locations. Inversion schemes provide vertical profile information and characterization of the retrieved products which are therefore relevant for contributing to the validation of MIPAS profiles in the stratosphere and upper troposphere. We have focused on the species HNO3 and N2O at 5 NDACC-sites distributed in both hemispheres, i.e., Jungfraujoch (46.5 degrees N) and Kiruna (68 degrees N) for the northern hemisphere, and Wollongong (34 degrees S), Lauder (45 degrees S) and Arrival Heights (78 degrees S) for the southern hemisphere. These ground-based data have been compared with MIPAS offline profiles (v4.61) for the year 2003, collocated within 1000 km around the stations, in the lower to middle stratosphere. To get around the spatial collocation problem, comparisons have also been made between the same ground-based FTIR data and the corresponding profiles resulting from the stratospheric 4D-VAR data assimilation system BASCOE constrained by MIPAS data. This paper discusses the results of the comparisons and the usefullness of using BASCOE profiles as proxies for MIPAS data. It shows good agreement between MIPAS and FTIR N2O partial columns: the biases are below 5% for all the stations and the standard deviations are below 7% for the three mid-latitude stations, and below 10% for the high latitude ones. The comparisons with BASCOE partial columns give standard deviations below 4% for the mid-latitude stations to less than 8% for the high latitude ones. After making some corrections to take into account the known bias due to the use of different spectroscopic parameters, the comparisons of HNO3 partial columns show biases below 3% and standard deviations below 15% for all the stations except Arrival Heights ( bias of 5%, standard deviation of 21%). The results for this species, which has a larger spatial variability, highlight the necessity of defining appropriate collocation criteria and of accounting for the spread of the observed air-masses. BASCOE appears to have more deficiencies in producing proxies of MIPAS HNO3 profiles compared to N2O, but the obtained standard deviation of less than 10% between BASCOE and FTIR is reasonable. Similar results on profiles comparisons are also shown in the paper, in addition to partial column ones. [less ▲]

Detailed reference viewed: 56 (11 ULg)
Full Text
Peer Reviewed
See detailValidation of MIPAS ClONO2 measurements
Hopfner, Michael; von Clarmann, Thomas; Fischer, H. et al

in Atmospheric Chemistry and Physics (2007), 7

Altitude profiles of ClONO2 retrieved with the IMK (Institut fur Meteorologie und Klimaforschung) science-oriented data processor from MIPAS/Envisat (Michelson Interferometer for Passive Atmospheric ... [more ▼]

Altitude profiles of ClONO2 retrieved with the IMK (Institut fur Meteorologie und Klimaforschung) science-oriented data processor from MIPAS/Envisat (Michelson Interferometer for Passive Atmospheric Sounding on Envisat) mid-infrared limb emission measurements between July 2002 and March 2004 have been validated by comparison with balloon-borne (Mark IV, FIRS2, MIPAS-B), airborne (MIPAS-STR), ground-based (Spitsbergen, Thule, Kiruna, Harestua, Jungfraujoch, Izana, Wollongong, Lauder), and spaceborne (ACE-FTS) observations. With few exceptions we found very good agreement between these instruments and MIPAS with no evidence for any bias in most cases and altitude regions. For balloon-borne measurements typical absolute mean differences are below 0.05 ppbv over the whole altitude range from 10 to 39 km. In case of ACE-FTS observations mean differences are below 0.03 ppbv for observations below 26 km. Above this altitude the comparison with ACE-FTS is affected by the photochemically induced diurnal variation of ClONO2. Correction for this by use of a chemical transport model led to an overcompensation of the photochemical effect by up to 0.1 ppbv at altitudes of 30-35 km in case of MIPAS-ACE-FTS comparisons while for the balloon-borne observations no such inconsistency has been detected. The comparison of MIPAS derived total column amounts with ground-based observations revealed no significant bias in the MIPAS data. Mean differences between MIPAS and FTIR column abundances are 0.11 +/- 0.12 x 10(14) cm(-2) (1.0 +/- 1.1%) and -0.09 +/- 0.19 x 10(14) cm(-2) (-0.8 +/- 1.7%), depending on the coincidence criterion applied. chi(2) tests have been performed to assess the combined precision estimates of MIPAS and the related instruments. When no exact coincidences were available as in case of MIPAS-FTIR or MIPAS-ACE-FTS comparisons it has been necessary to take into consideration a coincidence error term to account for chi(2) deviations. From the resulting chi(2) profiles there is no evidence for a systematic over/underestimation of the MIPAS random error analysis. [less ▲]

Detailed reference viewed: 28 (12 ULg)
Full Text
Peer Reviewed
See detailValidation of MIPAS HNO3 operational data
Wang, D. Y.; Hopfner, Michael; Blom, C. E. et al

in Atmospheric Chemistry and Physics (2007), 7(18), 4905-4934

Nitric acid (HNO3) is one of the key products that are operationally retrieved by the European Space Agency (ESA) from the emission spectra measured by the Michelson Interferometer for Passive Atmospheric ... [more ▼]

Nitric acid (HNO3) is one of the key products that are operationally retrieved by the European Space Agency (ESA) from the emission spectra measured by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) onboard ENVISAT. The product version 4.61/4.62 for the observation period between July 2002 and March 2004 is validated by comparisons with a number of independent observations from ground-based stations, aircraft/balloon campaigns, and satellites. Individual HNO3 profiles of the ESA MIPAS level-2 product show good agreement with those of MIPAS-B and MIPAS-STR (the balloon and aircraft version of MIPAS, respectively), and the balloon-borne infrared spectrometers MkIV and SPIRALE, mostly matching the reference data within the combined instrument error bars. In most cases differences between the correlative measurement pairs are less than 1 ppbv (5-10%) throughout the entire altitude range up to about 38 km (similar to 6 hPa), and below 0.5 ppbv (15-20% or more) above 30 km (similar to 17 hPa). However, differences up to 4 ppbv compared to MkIV have been found at high latitudes in December 2002 in the presence of polar stratospheric clouds. The degree of consistency is further largely affected by the temporal and spatial coincidence, and differences of 2 ppbv may be observed between 22 and 26 km (similar to 50 and 30 hPa) at high latitudes near the vortex boundary, due to large horizontal inhomogeneity of HNO3. Similar features are also observed in the mean differences of the MIPAS ESA HNO3 VMRs with respect to the ground-based FTIR measurements at five stations, aircraft-based SAFIRE-A and ASUR, and the balloon campaign IBEX. The mean relative differences between the MIPAS and FTIR HNO3 partial columns are within +/- 2%, comparable to the MIPAS systematic error of similar to 2%. For the vertical profiles, the biases between the MIPAS and FTIR data are generally below 10% in the altitudes of 10 to 30 km. The MIPAS and SAFIRE HNO3 data generally match within their total error bars for the mid and high latitude flights, despite the larger atmospheric inhomogeneities that characterize the measurement scenario at higher latitudes. The MIPAS and ASUR comparison reveals generally good agreements better than 10-13% at 20-34 km. The MIPAS and IBEX measurements agree reasonably well (mean relative differences within +/- 15%) between 17 and 32 km. Statistical comparisons of the MIPAS profiles correlated with those of Odin/SMR, ILAS-II, and ACE-FTS generally show good consistency. The mean differences averaged over individual latitude bands or all bands are within the combined instrument errors, and generally within 1, 0.5, and 0.3 ppbv between 10 and 40 km (similar to 260 and 4.5 hPa) for Odin/SMR, ILAS-II, and ACE-FTS, respectively. The standard deviations of the differences are between 1 to 2 ppbv. The standard deviations for the satellite comparisons and for almost all other comparisons are generally larger than the estimated measurement uncertainty. This is associated with the temporal and spatial coincidence error and the horizontal smoothing error which are not taken into account in our error budget. Both errors become large when the spatial variability of the target molecule is high. [less ▲]

Detailed reference viewed: 57 (17 ULg)
Full Text
See detailLa destruction de la couche d'ozone et ses implications en Région wallonne
Mahieu, Emmanuel ULg

Report (2007)

Stratospheric ozone is an important constituent of the Earth's atmosphere since it protects the biosphere from the most harmful ultraviolet radiations emitted by the sun. Some human activiites such as the ... [more ▼]

Stratospheric ozone is an important constituent of the Earth's atmosphere since it protects the biosphere from the most harmful ultraviolet radiations emitted by the sun. Some human activiites such as the use of man-mande chlorofluorocarbons have resulted in major destruction of ozone, in particular in the polar regions of the stratosphere. The Montreal Protocol has been successful in limiting the emissions of ozone depleting substances such as the complete ozone recovery is expected to take place in 2050 over northern mid-latitudes. [less ▲]

Detailed reference viewed: 75 (15 ULg)
See detailFTIR Observations at the Jungfraujoch Station for long-term monitoring of the Troposphere and Validation of the Space-based Sensors.
Mahieu, Emmanuel ULg; Zander, Rodolphe ULg; Demoulin, Philippe ULg et al

in Burrows, J.; Borrell, P. (Eds.) Measuring Tropospheric Trace Constituents from Space. (2007)

Detailed reference viewed: 16 (8 ULg)
See detailOptimisation of retrieval strategies using Jungfraujoch high-resolution FTIR observations for long-term trend studies and satellite validation.
Mahieu, Emmanuel ULg; Servais, Christian ULg; Duchatelet, Pierre ULg et al

in Burrows, J.; Borrell, P. (Eds.) Observing Tropospheric Trace Constituents from Space. (2007)

Detailed reference viewed: 4 (2 ULg)
Full Text
See detailLa destruction de la couche d'ozone
Mahieu, Emmanuel ULg; Theate, Pascal; Brahy, Vincent

in Delbeuck, C. (Ed.) Rapport analytique sur l'état de l'environnement wallon 2006-2007 (2007)

L’ozone (O3) est présent dans l’atmosphère terrestre en quantité limitée, avec un maximum de concentration entre 15 et 50 km d’altitude. Cette molécule y joue un rôle essentiel en filtrant les rayons ... [more ▼]

L’ozone (O3) est présent dans l’atmosphère terrestre en quantité limitée, avec un maximum de concentration entre 15 et 50 km d’altitude. Cette molécule y joue un rôle essentiel en filtrant les rayons solaires ultraviolets dont les effets sur les êtres vivants peuvent être nocifs. L’influence des activités humaines sur la couche d’ozone stratosphérique s’est manifestée dès le début des années 1980, principalement au dessus de l’Antarctique, où une baisse significative de la quantité totale d’ozone a été observée chaque printemps (ce que l’on nomme communément le «trou dans la couche d’ozone»). Depuis la mise en oeuvre du Protocole de Montréal en 1987, les émissions mondiales de substances halogénées à l’origine de cette destruction ont fortement diminué, laissant présager, sous nos latitudes, un retour à la normale de l’épaisseur de la couche d’ozone vers 2050. [less ▲]

Detailed reference viewed: 68 (4 ULg)
Full Text
See detailGround-based FTIR measurements at Ile de La Réunion: Observations, error analysis and comparisons with satellite data.
Senten, Cindy; De Mazière, Martine; Hermans, Christian et al

in Geophysical Research Abstracts (2007), 9

Ground-based Fourier-transform infrared (FTIR) spectroscopy is a powerful remote sensing technique to obtain information on the total column abundances and on the vertical distribution of various ... [more ▼]

Ground-based Fourier-transform infrared (FTIR) spectroscopy is a powerful remote sensing technique to obtain information on the total column abundances and on the vertical distribution of various constituents in the atmosphere. Many of these species are essential for the investigation of important atmospheric phenomena, such as the overall greenhouse effect or the stratospheric ozone decrease and recovery. In the frame of the Network for the Detection of Atmospheric Composition Change (NDACC), such observations have been made since many years at several measurement stations for the worldwide long-term monitoring of the atmospheric composition. In this work, we present the results from two short-term FTIR measurement campaigns in 2002 and 2004 at the Ile de La Réunion (21°S, 55°E), a complementary NDACC site in the subtropics, in the Indian Ocean. All spectra were recorded in solar absorption mode. The results discussed here concern the direct greenhouse gases methane (CH4), nitrous oxide (N2O) and ozone (O3), and the indirect greenhouse gases carbon monoxide (CO) and ethane (C2H6), as well as hydrogen cyanide (HCN) and stratospheric hydrogen chloride (HCl), hydrogen fluoride (HF) and nitric acid (HNO3). For the latter species (HCN, HCl, HF and HNO3), we show time series of total column amounts from the surface up to 60 km. For CO, CH4, N2O and O3, it is possible to derive additionally independent information on a few partial columns; these time series are discussed as well. A complete error budget of the retrieval products is given. Temporary mutually correlated enhancements of CO, C2H6and HCN have been observed. They have been traced back to biomass burning events in southern Africa and Madagascar using the FLEXPART model. Comparisons of our retrievals with correlative data from satellite experiments, such as ACE and MOPITT, and with available ozone soundings, show generally good agreements between the different data sets. [less ▲]

Detailed reference viewed: 55 (3 ULg)
Full Text
Peer Reviewed
See detailFirst space-based observations of formic acid (HCOOH): Atmospheric Chemistry Experiment austral spring 2004 and 2005 Southern Hemisphere tropical-mid-latitude upper tropospheric measurements
Rinsland, Curtis P.; Boone, Christopher D.; Bernath, Peter F. et al

in Geophysical Research Letters (2006), 33(23),

The first space-based measurements of upper tropospheric ( 110 - 300 hPa) formic acid (HCOOH) are reported from 0.02 cm(-1) resolution Atmospheric Chemistry Experiment (ACE) Fourier transform spectrometer ... [more ▼]

The first space-based measurements of upper tropospheric ( 110 - 300 hPa) formic acid (HCOOH) are reported from 0.02 cm(-1) resolution Atmospheric Chemistry Experiment (ACE) Fourier transform spectrometer solar occultation measurements at 16 degrees S - 43 degrees S latitude during late September to early October in 2004 and 2005. A maximum upper tropospheric HCOOH mixing ratio of 3.13 +/- 0.02 ppbv ( 1 ppbv = 10(-9) per unit volume), 1 sigma, at 10.5 km altitude was measured during 2004 at 29.97 degrees S latitude and a lower maximum HCOOH mixing ratio of 2.03 +/- 0.28 ppbv, at 9.5 km altitude was measured during 2005. Fire counts, back trajectories, and correlations of HCOOH mixing ratios with ACE simultaneous measurements of other fire products confirm the elevated HCOOH mixing ratios originated primarily from tropical fire emissions. A HCOOH emission factor relative to CO of 1.99 +/- 1.34 g kg(-1) during 2004 in upper tropospheric plumes is inferred from a comparison with lower mixing ratios measured during the same time period assuming HITRAN 2004 spectroscopic parameters. [less ▲]

Detailed reference viewed: 64 (11 ULg)
Full Text
Peer Reviewed
See detailA global inventory of stratospheric chlorine in 2004
Nassar, Ray; Bernath, Peter; Boone, Christopher D. et al

in Journal of Geophysical Research. Atmospheres (2006), 111(D22), 22312

[1] Total chlorine (Cl-TOT) in the stratosphere has been determined using the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) measurements of HCl, ClONO2, CH3Cl, CCl4, CCl3F (CFC ... [more ▼]

[1] Total chlorine (Cl-TOT) in the stratosphere has been determined using the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) measurements of HCl, ClONO2, CH3Cl, CCl4, CCl3F (CFC-11), CCl2F2 (CFC-12), CHClF2 (HCFC-22), CCl2FCClF2 (CFC-113), CH3CClF2 (HCFC-142b), COClF, and ClO supplemented by data from several other sources, including both measurements and models. Separate chlorine inventories were carried out in five latitude zones (60 degrees - 82 degrees N, 30 degrees - 60 degrees N, 30 degrees S - 30 degrees N, 30 degrees - 60 degrees S, and 60 degrees - 82 degrees S), averaging the period of February 2004 to January 2005 inclusive, when possible, to deal with seasonal variations. The effect of diurnal variation was avoided by only using measurements taken at local sunset. Mean stratospheric Cl-TOT values of 3.65 ppbv were determined for both the northern and southern midlatitudes (with an estimated 1 sigma accuracy of +/- 0.13 ppbv and a precision of +/- 0.09 ppbv), accompanied by a slightly lower value in the tropics and slightly higher values at high latitudes. Stratospheric Cl-TOT profiles in all five latitude zones are nearly linear with a slight positive slope in ppbv/km. Both the observed slopes and pattern of latitudinal variation can be interpreted as evidence of the beginning of a decline in global stratospheric chlorine, which is qualitatively consistent with the mean stratospheric circulation pattern and time lag necessary for transport. [less ▲]

Detailed reference viewed: 28 (14 ULg)
Full Text
Peer Reviewed
See detailComparisons between SCIAMACHY and ground-based FTIR data for total columns of CO, CH4, CO2 and N2O
Dils, Bart; De Mazière, Martine; Muller, Jean-François et al

in Atmospheric Chemistry and Physics (2006), 6

Total column amounts of CO, CH4, CO2 and N2O retrieved from SCIAMACHY nadir observations in its near-infrared channels have been compared to data from a ground-based quasi-global network of Fourier ... [more ▼]

Total column amounts of CO, CH4, CO2 and N2O retrieved from SCIAMACHY nadir observations in its near-infrared channels have been compared to data from a ground-based quasi-global network of Fourier-transform infrared ( FTIR) spectrometers. The SCIAMACHY data considered here have been produced by three different retrieval algorithms, WFM-DOAS (version 0.5 for CO and CH4 and version 0.4 for CO2 and N2O), IMAP- DOAS ( version 1.1 and 0.9 (for CO)) and IMLM (version 6.3) and cover the January to December 2003 time period. Comparisons have been made for individual data, as well as for monthly averages. To maximize the number of reliable coincidences that satisfy the temporal and spatial collocation criteria, the SCIAMACHY data have been compared with a temporal 3rd order polynomial interpolation of the ground-based data. Particular attention has been given to the question whether SCIAMACHY observes correctly the seasonal and latitudinal variability of the target species. The present results indicate that the individual SCIAMACHY data obtained with the actual versions of the algorithms have been significantly improved, but that the quality requirements, for estimating emissions on regional scales, are not yet met. Nevertheless, possible directions for further algorithm upgrades have been identified which should result in more reliable data products in a near future. [less ▲]

Detailed reference viewed: 58 (27 ULg)
Full Text
See detailPrecursor Gas Measurements (Chapter 2)
Notholt, J.; Bingemer, H.; Berresheim, H. et al

in Thomason, Larry W.; Peter, Thomas (Eds.) Assessment of Stratospheric Aerosol Properties (2006)

Assessments of stratospheric ozone have been conducted for nearly two decades and have evolved from describing ozone morphology to estimating ozone trends, and then to attribution of those trends ... [more ▼]

Assessments of stratospheric ozone have been conducted for nearly two decades and have evolved from describing ozone morphology to estimating ozone trends, and then to attribution of those trends. Stratospheric aerosol has only been integrated in assessments in the context of their effects on ozone chemistry and has not been critically evaluated itself. As a result, the Assessment of Stratospheric Aerosol Properties (ASAP) has been carried out by the WCRP project on Stratospheric Process and their Role in Climate (SPARC). The objective of this report is to present a systematic analysis of the state of knowledge of stratospheric aerosols including their precursors. It includes an examination of precursor concentrations and trends, measurements of stratospheric aerosol properties, trends in those properties, and modeling of aerosol formation, transport, and distribution in both background and volcanic conditions. The scope of this report is extensive; however, some aspects of stratospheric aerosol science have been deliberately excluded. For instance, we have not attempted to include an examination of polar stratospheric clouds (PSCs) or other clouds (such as cirrus clouds) occurring at or above the tropopause except in as much as they influence aerosol observations. Polar stratospheric clouds are the subject of a separate SPARC activity. We have produced a gap-free aerosol data base for use beyond this report. This required some new analysis that has not previously appeared in the technical literature. Similarly, the trend analysis required the development of a new analysis technique that is the subject of an article published in the Journal of Geophysical Research. New work is clearly identified in the present report. [less ▲]

Detailed reference viewed: 26 (1 ULg)
Full Text
Peer Reviewed
See detailLong-term trend of CH4 at northern mid-latitudes: Comparison between ground-based infrared solar and surface sampling measurements
Rinsland, Curtis P.; Goldman, Aaron; Elkins, James W. et al

in Journal of Quantitative Spectroscopy & Radiative Transfer (2006), 97(3), 457-466

We report average tropospheric CH4 volume mixing ratios retrieved from a 27 year time series of high spectral resolution infrared solar absorption measurements recorded between May 1977 and July 2004 at ... [more ▼]

We report average tropospheric CH4 volume mixing ratios retrieved from a 27 year time series of high spectral resolution infrared solar absorption measurements recorded between May 1977 and July 2004 at the US National Solar Observatory station on Kitt Peak (31.9 degrees N, 111.6 degrees W, 2.09 km altitude) and their comparison with surface in situ sampling measurements recorded between 1983 and 2004 at the Climate Monitoring and Diagnostics Laboratory (CMDL) station at Niwot Ridge, Colorado (40.0 degrees N, 105.5 degrees W, 3013 m altitude). The two measurement sets therefore overlap for the 1983-2004 time period. An average tropospheric volume mixing ratios of 1814 +/- 48 ppbv (1 ppbv = 10(-9) per unit volume) has been derived from the solar absorption time series with a best-fit increase rate trend equal to 8.26 +/- 2.20 ppbv yr(-1) in 1983 decreasing to 1.94 +/- 3.69 ppbv yr(-1) in 2003. The CMDL measurements also show a continuous long-term CH4 volume mixing ratio rise, with subsequent slowing down. A mean ratio of the retrieved average tropospheric volume mixing ratio to the CMDL volume mixing ratio for the overlapping time period of 1.038 +/- 0.034 indicates agreement between both data sets within the quantified experimental errors. (C) 2005 Elsevier Ltd. All rights reserved. [less ▲]

Detailed reference viewed: 29 (3 ULg)
Full Text
Peer Reviewed
See detailLine-by-line calculations of thermal infrared radiation representative for global condition: CFC-12 as an example
Myhre, Gunnar; Stordal, Frode; Gausemel, Ingvil et al

in Journal of Quantitative Spectroscopy & Radiative Transfer (2006), 97(3), 317-331

We estimate a current direct radiative forcing due to CFC-12 of 0.18 Wm(-2), which is likely to be the peak radiative forcing for CFC-12. Global measurements of CFC-12 show at present an almost negligible ... [more ▼]

We estimate a current direct radiative forcing due to CFC-12 of 0.18 Wm(-2), which is likely to be the peak radiative forcing for CFC-12. Global measurements of CFC-12 show at present an almost negligible trend for CFC-12 and measurement in an industrialized region show evidence that the peak concentration is reached. It is expected that concentration of CFC-12 in industrialized regions begins to decline 1-3 years before the global concentration. Our radiative forcing calculations are based on a line-by-line model appropriate for simulation of global mean radiative forcing, including clouds and stratospheric temperature adjustment. The radiative forcing of 0.33 Wm(-2)/ppbv is close to earlier published results for this compound. New spectroscopic measurements for CFC-12 are performed and compared to previously published results. (C) 2005 Elsevier Ltd. All rights reserved. [less ▲]

Detailed reference viewed: 55 (3 ULg)