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See detailThe evolution of inorganic chlorine above the Jungfraujoch station: an update.
Mahieu, Emmanuel ULg; Duchatelet, Pierre ULg; Zander, Rodolphe ULg et al

in Zerefos, C. S. (Ed.) Proceedings of the 20th Quadrennial Ozone Symposium (2004)

Within the frame of the NDSC, the total vertical column abundances of HCl and ClONO2, by far the two most important inorganic chlorine reservoirs at northern mid-latitudes, have been further monitored ... [more ▼]

Within the frame of the NDSC, the total vertical column abundances of HCl and ClONO2, by far the two most important inorganic chlorine reservoirs at northern mid-latitudes, have been further monitored above the Jungfraujoch station (Swiss Alps, 46.5ºN, 8.0ºE, 3580m a.s.l.), by analyzing infrared solar absorption spectra recorded with very high-resolution Fourier spectrometers. The mean temporal evolution of the sum of their monthly mean abundance time series indicates that the total stratospheric inorganic chlorine loading (Cly) has decreased slowly (-0.7+/-0.3%/yr, 1-sigma) since it peaked in late 1996, at the limit of being statistically significant at the 2-sigma level. Comparison with model calculations and with the evolution of surface total organic chlorine will also be discussed. [less ▲]

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See detailGround-based FTIR measurements of CO from the Jungfraujoch: characterisation and comparison with in situ surface and MOPITT data
Barret, Brice; De Mazière, Martine; Mahieu, Emmanuel ULg

in Atmospheric Chemistry and Physics (2003), 3

CO vertical profiles have been retrieved from solar absorption FTIR spectra recorded at the NDSC station of the Jungfraujoch ( 46.5 degreesN, 8degrees E and 3580 ma. s. l.) for the period from January ... [more ▼]

CO vertical profiles have been retrieved from solar absorption FTIR spectra recorded at the NDSC station of the Jungfraujoch ( 46.5 degreesN, 8degrees E and 3580 ma. s. l.) for the period from January 1997 to May 2001. The characterisation of these profiles has been established by an information content analysis and an estimation of the error budgets. A partial validation of the profiles has been performed through comparisons with correlative measurements. The average volume mixing ratios ( vmr) in the 3 km layer above the station have been compared with coincident surface measurements. The agreement between monthly means from both measurement techniques is very good, with a correlation coefficient of 0.87, and no significant bias observed. The FTIR total columns have also been compared to CO partial columns above 3580 ma. s. l. derived from the MOPITT ( Measurement Of Pollution In The Troposphere) instrument for the period March 2000 to May 2001. Relative to the FTIR columns, the MOPITT partial columns exhibit a positive bias of 8 +/- 8% for daytime and of 4 +/- 7% for nighttime measurements. [less ▲]

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See detailPost-Mount Pinatubo eruption ground-based infrared stratospheric column measurements of HNO3, NO, and NO2 and their comparison with model calculations
Rinsland, Curtis P.; Weisenstein, Debra K.; Ko, Malcolm K. W. et al

in Journal of Geophysical Research. Atmospheres (2003), 108(D15),

[1] Infrared solar spectra recorded between July 1991 to March 1992 and November 2002 with the Fourier transform spectrometer on Kitt Peak (31.9 degrees N latitude, 111.6 degrees W longitude, 2.09 km ... [more ▼]

[1] Infrared solar spectra recorded between July 1991 to March 1992 and November 2002 with the Fourier transform spectrometer on Kitt Peak (31.9 degrees N latitude, 111.6 degrees W longitude, 2.09 km altitude) have been analyzed to retrieve stratospheric columns of HNO3, NO, and NO2. The measurements cover a decade time span following the June 1991 Mount Pinatubo volcanic eruption and were recorded typically at 0.01 cm(-1) spectral resolution. The measured HNO3 stratospheric column shows a 20% decline from 9.16 x 10(15) molecules cm(-2) from the first observation in March 1992 to 7.40 x 10(15) molecules cm(-2) at the start of 1996 reaching a broad minimum of 6.95 x 10(15) molecules cm(-2) thereafter. Normalized daytime NO and NO2 stratospheric column trends for the full post-Pinatubo eruption time period equal (+ 1.56 +/- 0.45)% yr(-1), 1 sigma, and (+ 0.52 +/- 0.32)% yr(-1), 1 sigma, respectively. The long-term trends are superimposed on seasonal cycles with ~10% relative amplitudes with respect to mean values, winter maxima for HNO3 and summer maxima for NO and NO2. The measurements have been compared with two-dimensional model calculations utilizing version 6.1 Stratospheric Aerosol and Gas Experiment ( SAGE) II sulfate aerosol surface area density measurements through 1999 and extended to the end of the time series by repeating the 1999 values. The model-calculated HNO3, NO, and NO2 stratospheric column time series agree with the measurements to within ~8% after taking into account the vertical sensitivity of the ground-based measurements. The consistency between the measured and model-calculated stratospheric time series confirms the decreased impact on stratospheric reactive nitrogen chemistry of the key heterogeneous reaction that converts reactive nitrogen to its less active reservoir form as the lower-stratospheric aerosol surface area density declined by a factor of ~20 after the eruption maximum. [less ▲]

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See detailLong-term trends of inorganic chlorine from ground-based infrared solar spectra: Past increases and evidence for stabilization
Rinsland, Curtis P.; Mahieu, Emmanuel ULg; Zander, Rodolphe ULg et al

in Journal of Geophysical Research (2003), 108(D8), 4252

Long-term time series of hydrogen chloride (HCl) and chlorine nitrate (ClONO2) total column abundances has been retrieved from high spectral resolution ground-based solar absorption spectra recorded with ... [more ▼]

Long-term time series of hydrogen chloride (HCl) and chlorine nitrate (ClONO2) total column abundances has been retrieved from high spectral resolution ground-based solar absorption spectra recorded with infrared Fourier transform spectrometers at nine NDSC (Network for the Detection of Stratospheric Change) sites in both Northern and Southern Hemispheres. The data sets span up to 24 years and most extend until the end of 2001. The time series of Cly (defined here as the sum of the HCl and ClONO2 columns) from the three locations with the longest time-span records show rapid increases until the early 1990s superimposed on marked day-to-day, seasonal and inter-annual variability. Subsequently, the buildup in Cly slows and reaches a broad plateau after 1996, also characterized by variability. A similar time evolution is also found in the total chlorine concentration at 55 km altitude derived from Halogen Occultation Experiment (HALOE) global observations since 1991. The stabilization of inorganic chlorine observed in both the total columns and at 55 km altitude indicates that the near-global 1993 organic chlorine (CCly) peak at the Earth’s surface has now propagated over a broad altitude range in the upper atmosphere, though the time lag is difficult to quantify precisely from the current data sets, due to variability. We compare the three longest measured time series with two-dimensional model calculations extending from 1977 to 2010, based on a halocarbon scenario that assumes past measured trends and a realistic extrapolation into the future. The model predicts broad Cly maxima consistent with the long-term observations, followed by a slow Cly decline reaching 12–14% relative to the peak by 2010. The data reported here confirm the effectiveness of the Montreal Protocol and its Amendments and Adjustments in progressively phasing out the major man-related perturbations of the stratospheric ozone layer, in particular, the anthropogenic chlorine-bearing source gases. [less ▲]

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See detailSF6 ground-based infrared solar absorption measurements: long-term trend, pollution events, and a search for SF5CF3 absorption
Rinsland, Curtis P.; Goldman, Aaron; Stephen, T. M. et al

in Journal of Quantitative Spectroscopy & Radiative Transfer (2003), 78(1), 41-53

Infrared solar spectra recorded with the Fourier transform spectrometer in the McMath solar telescope complex on Kitt Peak (31.9degreesN latitude, 111.6degreesW, 2.09 km altitude), southwest of Tucson ... [more ▼]

Infrared solar spectra recorded with the Fourier transform spectrometer in the McMath solar telescope complex on Kitt Peak (31.9degreesN latitude, 111.6degreesW, 2.09 km altitude), southwest of Tucson, Arizona, have been analyzed to retrieve average SF6 tropospheric mixing ratios over a two-decade time span. The analysis is based primarily on spectral fits to absorption by the intense, unresolved nu(3) band Q branch at 947.9 cm(-1). A best fit to measurements recorded with SF6 near typical background concentrations yields a SF6 increase in the average tropospheric mixing ratio from 1.13 pptv (10(-12) per unit volume) in March 1982 to 3.77 pptv in March 2002. The long-term increase by a factor of 3.34 over the time span is consistent with the rapid growth of surface mixing ratios measured in situ at Northern Hemisphere remote stations, though the infrared measurements show a large scatter. Average tropospheric mixing ratio enhancements above background by 2-3 orders of magnitude have been identified in spectra recorded on 5 days between November 1988 and April 1997. These spectra were individually analyzed in an attempt to detect the strongest 8-12 mum band of SF5CF3, a molecule recently identified with an atmospheric growth that has closely paralleled the rise in SF6 during the past three decades. Absorption by the strongest SF5CF3 band was predicted to be above the noise level in the Kitt Peak spectrum with the highest average mean tropospheric SF6 mixing ratio, assuming the reported atmospheric SF5CF3/SF6 ratio and a room temperature absorption cross sections reported for the SF5CF3 903-cm(-1) band. An upper limit of 8 x 10(15) molecules cm(-2) for the SF5CF3 total column was estimated for this case. We hypothesize that the highly elevated SF6 levels above Kitt Peak resulted from a local release experiment rather than production via electrochemical fluoridation of intermediate products, the proposed source of atmospheric SF5CF3. The absence of the SF5CF3 feature in the spectra with elevated SF6 is consistent with the absence of SF5CF3 reported in a pure SF6 sample. Published by Elsevier Science Ltd. [less ▲]

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See detailControlled substances and other source gases, Chapter 1 of the Scientific Assessment of Ozone Depletion: 2002
Montzka, S. A.; Fraser, P. J.; Butler, J. H. et al

in Nohende Ajavon, Ayité-Lô; Albritton, Daniel L.; Mégie, Gérard (Eds.) et al Scientific Assessment of Ozone Depletion: 2002 (2003)

This chapter provides an update on scientific progress since the previous Scientific Assessment of Ozone Depletion (WMO, 1999) regarding ozone-depleting substances (ODSs) in the atmosphere. This includes ... [more ▼]

This chapter provides an update on scientific progress since the previous Scientific Assessment of Ozone Depletion (WMO, 1999) regarding ozone-depleting substances (ODSs) in the atmosphere. This includes a discussion of the latest available data for observed trends in the troposphere and stratosphere, emissions, lifetimes, Ozone Depletion Potentials (ODPs), and Global Warming Potentials (GWPs). On the basis of this updated informaion, we relate observations of ODSs in the atmosphere to expectations, and discuss the evidence that the Montreal Protocol is effectively reducing ozone-depleting gases in the atmosphere. [less ▲]

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See detailValidation of ENVISAT-1 Level-2 Products Related to Lower Atmosphere O3 and NOy Chemistry by a FTIR Quasi-global Network
De Mazière, Martine; Coosemans, Thierry; Barret, Brice et al

in Proceedings of Envisat Validation Workshop, Frascati, Italy, December 9-13, 2002, ESA SP-531, 2003 (2003)

A coordinated action involving eleven stations of the ground -based Network for Detection of Stratospheric Change (NDSC) equipped with Fourier transform infrared (FTIR) instruments was conducted to ... [more ▼]

A coordinated action involving eleven stations of the ground -based Network for Detection of Stratospheric Change (NDSC) equipped with Fourier transform infrared (FTIR) instruments was conducted to contribute to the validation of the three atmospheric chemistry instruments onboard ENVISAT, that are MIPAS, SCIAMACHY and GOMOS. The target products for validation are total columns of O3, CH4, CO and some important NOy species (NO2, HNO3, NO) and the source gas N2O. Together the eleven stations cover the latitudes between 79 °N and 78°S, including polar, mid-latitude and subtropical and tropical locations. The goal is to contribute to the assessment of the data quality of the aforementioned ENVISAT instruments, from a quasi -global perspective. The period of intensive ground-based data collection for the benefit of the ENVISAT Validation Commissioning Phase that is dealt with in the present paper is July 15 to December 1, 2002. The FTIR network involved collected a data set corresponding to an equivalent of approximately 400 days of measurements; about three quarter of the data have already been submitted to the ENVISAT Calval database and are included in the present work. Unfortunately, the distribution of ENVISAT data has been slow and limited. Only a limited number of coincidences has been found for making data inter -comparisons. Therefore, the conclusions drawn in this paper are very preliminary and cover only a limited set of data products from SCIAMACHY only. Our findings up to now concerning the above mentioned target products are the following: (1) SCIAMACHY near infrared operational products (CO, CH4, N 2O) have no scientific meaning yet, (2), the operational SCIAMACHY total vertical O3 column product derived in the ultraviolet window has undergone some improvements with changing versions of the processor(s) but it still underestimates the column by about 5 – 10 %, (3), the operational SCIAMACHY total vertical O3 column product derived in the visible window is unrealistically large, and (4), the operational NO2 total column product from SCIAMACHY seems to largely overestimate the real column, but very few coincidences and large dispersions of the data do inhibit any further conclusion at present. In a next phase, the same ground-based correlative data set will be exploited to further validate the ENVISAT data as soon as more and reprocessed data will be distributed. [less ▲]

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See detailMonitoring of the variability and long-term evolution of tropospheric constituents by Infrared solar absorption spectrometry at the Jungfraujoch, Switzerland.
Zander, Rodolphe ULg; Mahieu, Emmanuel ULg; Duchatelet, Pierre ULg et al

in Borrell, P.; Borrell, P. M.; Burrows, J. P. (Eds.) et al Sounding the Troposphere from Space: A new era for Atmospheric Chemistry. (2003)

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See detailUpdating the Jungfraujoch FTIR databases : current status
Duchatelet, Pierre ULg; Mahieu, Emmanuel ULg; Zander, Rodolphe ULg et al

(2003)

Since the middle of the 20th century, the University of Liège has been active at the International Scientific Station of the Jungfraujoch (ISSJ) in the Swiss Alps (46.5°N, 8.0°E, 3580m asl) to study the ... [more ▼]

Since the middle of the 20th century, the University of Liège has been active at the International Scientific Station of the Jungfraujoch (ISSJ) in the Swiss Alps (46.5°N, 8.0°E, 3580m asl) to study the chemical composition of both the solar photosphere and the Earth’s atmosphere. Since 1989, the ISSJ is an accepted site of the northern midlattitude primary Alpine station of the NDSC (Network for the Detection of Stratospheric Change). This acceptance resulted from earlier monitoring activities by Ulg of a large number of atmospheric constituents. Within the NDSC frame, a special attention and many efforts have been devoted to the monitoring of the most important atmospheric constituents involved both in the erosion of stratospheric ozone and in the greenhouse capacity of the troposphere, after it became clear that human activities have a direct impact on these two processes. Using two high resolution Fourier transform infrared (FTIR) spectrometers, over 25000 wide-band solar spectra encompassing nearly 1700 days since the mid 1980s have been recorded and analyzed to study, quasi simultaneously and repeatedly, local, seasonal and secular variations of some 20 gaseous telluric species. So far, most results have been reported, demonstrating the power of infrared spectrometric solar observations to characterize the chemical composition of the atmosphere. These datas, archived in terms of total vertical column abundances (e.g., at the NDSC-Data Host Facility; http://www.ndsc.ws), are expressed in number molecules per cm2 above the site using best-know input parameters (i.e. spectroscopic-, instrumental-, environmental-) in the retrieval procedure. Meanwhile, more sophisticated algorithms, based on the “Rodgers” optimal estimation method, have been developed, allowing to derive partial tropospheric- and stratospheric columns for various species, including HCl, ClONO2, O3, HF, CO, N2O, CH4, HCN, OCS. This contribution reports related results for HCl and ClONO2. [less ▲]

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See detailVALIDATION OF ENVISAT-1 LEVEL-2 PRODUCTS RELATED TO LOWER ATMOSPHERE O3 AND NOy CHEMISTRY BY A FTIR QUASI-GLOBAL NETWORK
De Mazière, M.; Coosemans, T.; Barret, B. et al

Scientific conference (2002, December)

A coordinated action involving eleven stations of the ground-based Network for Detection of Stratospheric Change (NDSC) equipped with Fourier transform infrared (FTIR) instruments was conducted to ... [more ▼]

A coordinated action involving eleven stations of the ground-based Network for Detection of Stratospheric Change (NDSC) equipped with Fourier transform infrared (FTIR) instruments was conducted to contribute to the validation of the three atmospheric chemistry instruments onboard ENVISAT, that are MIPAS, SCIAMACHY and GOMOS. The target products for validation are total columns of O3, CH4, CO and some important NOy species (NO2, HNO3, NO) and the source gas N2O. Together the eleven stations cover the latitudes between 79 °N and 78°S, including polar, mid -latitude and subtropical and tropical locations. The goal is to contribute to the assessment of the data quality of the aforementioned ENVISAT instruments, from a quasi-global perspective. The period of intensive ground-based data collection for the benefit of the ENVISAT Validation Commissioning Phase that is dealt with in the present paper is July 15 to December 1, 2002. The FTIR network involved collected a data set corresponding to an equivalent of approximately 400 days of measurements; about three quarter of the data have already been submitted to the ENVISAT Calval database and are included in the present work. Unfortunately, the distribution of ENVISAT data has been slow and limited. Only a limited number of coincidences has been found for making data inter-comparisons. Therefore, the conclusions drawn in this paper are very preliminary and cover only a limited set of data products from SCIAMACHY only. Our findings up to now concerning the above mentioned target products are the following: (1) SCIAMACHY near infrared operational products (CO, CH4, N2O) have no scientific meaning yet, (2), the operational SCIAMACHY total vertical O3 column product derived in the ultraviolet window has undergone some improvements with changing versions of the processor(s) but it still underestimates the column by about 5 – 10 %, (3), the operational SCIAMACHY total vertical O3 column product derived in the visible window is unrealistically large, and (3), the operational NO2 total column product from SCIAMACHY seems to largely overestimate the real column, but very few coincidences and large dispersions of the data do inhibit any further conclusion at present. In a next phase, the same ground-based correlative data set will be exploited to further validate the ENVISAT data as soon as more and reprocessed data will be distributed. [less ▲]

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See detailAtmospheric Trace Molecule Spectroscopy (ATMOS) experiment version 3 data retrievals
Irion, Fredrick W.; Gunson, Michael R.; Toon, Geoff C. et al

in Applied Optics (2002), 41(33), 6968-6979

Version 3 of the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment data set for some 30 trace and minor gas profiles is available. From the IR solar-absorption spectra measured during four Space ... [more ▼]

Version 3 of the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment data set for some 30 trace and minor gas profiles is available. From the IR solar-absorption spectra measured during four Space Shuttle missions (in 1985, 1992, 1993, and 1994), profiles from more than 350 occultations were retrieved from the upper troposphere to the lower mesosphere. Previous results were unreliable for tropospheric retrievals, but with a new global-fitting algorithm profiles are reliably returned down to altitudes as low as 6.5 km (clouds permitting) and include notably improved retrievals of H2O, CO, and other species. Results for stratospheric water are more consistent across the ATMOS spectral filters and do not indicate a net consumption of H-2 in the upper stratosphere. A new sulfuric-acid aerosol product is described. An overview of ATMOS Version 3 processing is presented with a discussion of estimated uncertainties. Differences between these Version 3 and previously reported Version 2 ATMOS results are discussed. Retrievals are available at http://atmos.jpl.nasa.gov/atmos. (C) 2002 Optical Society of America. [less ▲]

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See detailGround-based infrared spectroscopic measurements of carbonyl sulfide: Free tropospheric trends from a 24-year time series of solar absorption measurements
Rinsland, Curtis P.; Goldman, Aaron; Mahieu, Emmanuel ULg et al

in Journal of Geophysical Research. Atmospheres (2002), 107(D22),

[1] Solar absorption spectra recorded over a 24-year time span have been analyzed to retrieve average free tropospheric mixing ratios of carbonyl sulfide (OCS). The measurements were recorded with the ... [more ▼]

[1] Solar absorption spectra recorded over a 24-year time span have been analyzed to retrieve average free tropospheric mixing ratios of carbonyl sulfide (OCS). The measurements were recorded with the Fourier transform spectrometer located in the U. S. National Solar Observatory McMath solar telescope facility on Kitt Peak (altitude 2.09 km, lat. 31.9degreesN, long. 111.6degreesW), southwest of Tucson, Arizona, and were obtained on 167 days between May 1978 and February 2002, typically at 0.01-cm(-1) spectral resolution. A best fit to the time series shows an average mixing ratio of 566 pptv (1 pptv = 10(-12) per unit volume) between 2.09 and 10 km, a small but statistically significant long-term decrease equal to (-0.25 +/- 0.04)% yr(-1), 1 sigma, and a seasonal variation with a summer maximum, a winter minimum, and a peak amplitude of (1.3 +/- 0.4)%, 1 sigma, relative to the mean. Although a statistically significant decline and seasonal variation have been detected, both are exceedingly small. The present results confirm and extend earlier studies showing that the OCS free tropospheric abundance at northern midlatitudes has remained nearly constant over the last decades. [less ▲]

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See detailStratospheric HF column abundances above Kitt Peak (31.9 degrees N latitude): trends from 1977 to 2001 and correlations with stratospheric HCl columns
Rinsland, Curtis P.; Zander, Rodolphe ULg; Mahieu, Emmanuel ULg et al

in Journal of Quantitative Spectroscopy & Radiative Transfer (2002), 74(2), 205-216

Time series of stratospheric hydrogen fluoride (HF) column abundances have been derived from infrared solar absorption spectra recorded for 195 days between May 1977 and June 2001 at a spectral resolution ... [more ▼]

Time series of stratospheric hydrogen fluoride (HF) column abundances have been derived from infrared solar absorption spectra recorded for 195 days between May 1977 and June 2001 at a spectral resolution of typically 0.01 cm(-1). The measurements were made at the US National Solar Observatory facility on Kitt Peak, Arizona, USA (31.9degreesN, 111.6degreesW, 2.09 km altitude) and have been analyzed with the SFIT2 algorithm, which is based on a semi-empirical application of the optimal estimation method. The measurements show a continuous buildup of the stratospheric HF column over the 24-yr period superimposed on short-term variations and a seasonal cycle with spring maxima and autumn minima. The measured stratospheric HF columns increased by a factor of 4.7, from 2.03 x 10(14) molecule cm(-2) in May 1977 to 9.49 x 10(14) molecule cm(-2) in June 2001. A best fit with a model that assumes an exponential increase in the stratospheric HF column with time superimposed on a sinusoidal seasonal cycle yields an average rate of stratospheric HF column increase of (4.30 +/- 0.15% yr(-1)), 1 sigma. The rate of increase is nearly a factor of two less than that derived previously from 1977 to 1990 Kitt Peak total columns, which indicates a significant slowdown in the increase rate during the 1990s, consistent with the trends from recent near-global lower mesospheric satellite remote and surface in situ measurements. Day-to-day stratospheric HIT columns are highly correlated with the same day stratospheric HCl columns as a result of common transport of lower and higher latitude air to above the station. Extrapolation of the linear relation between the two sets of stratospheric columns indicates a background HCl column of 1 x 10(15) molecule cm(-2) for zero HF, consistent with a previous estimate from 1977 to 1990 HF and HCl Kitt Peak total column measurements and a 1973 HCl measurement above the station. (C) 2002 Elsevier Science Ltd. All rights reserved. [less ▲]

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See detailMultiyear infrared solar spectroscopic measurements of HCN, CO, C2H6,and C2H2 tropospheric columns above Lauder, New Zealand (45 degrees S latitude)
Rinsland, Curtis P.; Jones, Nicholas B.; Connor, Brian J. et al

in Journal of Geophysical Research. Atmospheres (2002), 107(D14),

[1] Near-simultaneous, 0.0035 or 0.007 cm(-1) resolution infrared solar absorption spectra of tropospheric HCN, C2H2, CO, and C2H6 have been recorded from the Network for the Detection of Stratospheric ... [more ▼]

[1] Near-simultaneous, 0.0035 or 0.007 cm(-1) resolution infrared solar absorption spectra of tropospheric HCN, C2H2, CO, and C2H6 have been recorded from the Network for the Detection of Stratospheric Change station in Lauder, New Zealand (45.04degreesS, 169.68degreesE, 0.37 km altitude). All four molecules were measured on over 350 days with HCN and C2H2 reported for the first time based on a new analysis procedure that significantly increases the effective signal-to-noise of weak tropospheric absorption features in the measured spectra. The CO measurements extend by 2.5 years a database of measurements begun in January 1994 for CO with improved sensitivity in the lower and middle troposphere. The C2H6 measurements lengthen a time series begun in July 1993 with peak sensitivity in the upper troposphere. Retrievals of all four molecules were obtained with an algorithm based on the semiempirical application of the Rodgers optimal estimation technique. Columns are reported for the 0.37- to 12-km-altitude region, approximately the troposphere above the station. The seasonal cycles of all four molecules are asymmetric, with minima in March-June and sharp peaks and increased variability during August-November, which corresponds to the period of maximum biomass burning near the end of the Southern Hemisphere tropical dry season. Except for a possible HCN column decrease, no evidence was found for a statistically significant long-term trend. [less ▲]

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See detailATMOS version 3 water vapor measurements: Comparisons with observations from two ER-2 Lyman-alpha hygrometers, MkIV, HALOE, SAGE II, MAS, and MLS
Michelsen, Hope A.; Manney, Gloria L.; Irion, Fredrick W. et al

in Journal of Geophysical Research. Atmospheres (2002), 107(D3),

[1] We have compared a new version of Atmospheric Trace Molecule Spectroscopy Experiment (ATMOS) retrievals (version 3) of stratospheric and mesospheric water vapor with observations from shuttleborne ... [more ▼]

[1] We have compared a new version of Atmospheric Trace Molecule Spectroscopy Experiment (ATMOS) retrievals (version 3) of stratospheric and mesospheric water vapor with observations from shuttleborne, satelliteborne, balloonborne, and aircraftborne instruments. These retrievals show agreement to within 5% with the MkIV observations in the middle and lower stratosphere. ATMOS agrees with the National Oceanic and Atmospheric Administration (NOAA) Lyman-alpha hygrometer to within 5% except for features with spatial scales less than the vertical resolution of ATMOS (such as the lower stratospheric seasonal cycle). ATMOS observations are 10-16% lower than measurements from the Harvard Lyman-alpha hygrometer in the lower stratosphere and are 7-14% higher than those from the Microwave Limb Sounder (MLS; prototype version 0104) throughout most of the stratosphere. Agreement is within 7% with the Millimeter-Wave Atmospheric Sounder (MAS; version 20) in the middle and upper stratosphere, but differences are closer to 13% in the lower stratosphere. Throughout the stratosphere, agreement is within 8% with the Halogen Occultation Experiment (HALOE; version 19). ATMOS data from 1994 show agreement with the Stratospheric Aerosol and Gas Experiment II (SAGE II; version 6) values to within 8% in the middle stratosphere, but ATMOS observations are systematically higher than those from SAGE II by as much as 41% in the lower stratosphere. In contrast, ATMOS 1985 values are systematically similar to50% lower than SAGE II values from sunset occultations in the lower stratosphere near 70 hPa but appear to be in better agreement with sunrise occultations. Version 3 retrievals in the upper stratosphere and lower mesosphere are typically 5-10% lower than version 2 values between 1 and 0.05 hPa. This reduction improves agreement with HALOE, MAS, and MLS upper atmospheric observations, but ATMOS values still tend to be higher than values from these instruments in the middle mesosphere. Agreement among the instruments compared here (except for SAGE II) is generally within 15% in the middle to lower stratosphere and mesosphere and within 10% in the middle to upper stratosphere. At altitudes near 30 km, all instruments (including SAGE II) agree to within 10%. [less ▲]

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See detailPotential of the NDSC in support of the Kyoto Protocol: Examples from the station Jungfraujoch, Switzerland
Zander, Rodolphe ULg; Mahieu, Emmanuel ULg; Servais, Christian ULg et al

in Van Ham, J.; Baede, A. P. M.; Guicherit, R. (Eds.) et al Non-CO2 Greenhouse Gases: Scientific Understanding, Control Options and Policy Aspects (2002)

This paper gives a brief description and “raison d’être” of the Network for the Detection of Stratospheric Change (NDSC) as well as its key research tasks to address the broader goal of monitoring ... [more ▼]

This paper gives a brief description and “raison d’être” of the Network for the Detection of Stratospheric Change (NDSC) as well as its key research tasks to address the broader goal of monitoring atmospheric changes and to identify their causes and related impacts on mankind’s environment. While the Network has primarily focussed, thus far, on monitoring the ozone layer and assessing global compliance with the Montreal Protocol, ongoing implementations and new capabilities have enabled it to adapt to more recent political developments such as the Kyoto Proto-col on substances affecting the climate system. Examples of activities in support of the latter are reported, based on infrared solar observations at the Jungfraujoch station. [less ▲]

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See detailL'évolution du chlore inorganique au-dessus du Jungfraujoch et le Protocole de Montréal
Mahieu, Emmanuel ULg

Doctoral thesis (2001)

The main objective of this work was to determine the inorganic chlorine budget (Cly) at northern midlatitudes, to establish its variability and to study its temporal evolution over the last fifteen years ... [more ▼]

The main objective of this work was to determine the inorganic chlorine budget (Cly) at northern midlatitudes, to establish its variability and to study its temporal evolution over the last fifteen years. To achieve this, we have analyzed the observational database made of IR solar spectra recorded mainly with high resolution Fourier transform spectrometers installed at the International Scientific Station of the Jungfraujoch, located in the Swiss Alps, at 3580m altitude. The analysis of ATMOS (Atmospheric Trace Molecule Spectroscopy) data allowed us to first establish that HCl and ClONO2 account for more than 93% of the total inorganic chlorine, and that the summation of their vertical column abundances is an excellent surrogate of the Cly evolution at midlatitudes. Thus, we have derived HCl and ClONO2 total column abundance time series above the Jungfraujoch to analyze their temporal evolutions. Their combination has allowed us to show that the Cly increase between 1986 and 1995 (+50%) resulted primarily from the photodissociation of long-lived chlorinated source gas, in particular the manmade chlorofluorocarbons (CFC), progressively transported to the stratosphere after their release at the Earth surface during the seventies and the eighties. The organic chlorine (CCly) decrease in the troposphere resulting from regulations adopted by the Montreal Protocol, its Amendments and Adjustments, led to a progressive stabilization of Cly in the stratosphere. However, statistical analysis and interannual variability characterizing our time series, which extend to the end of 2000, prevent any final determination of the occurrence of the Cly maximum observed here at the end of October 1996, and of its subsequent decrease. We also show that chlorine partitioning among the chlorinated reservoirs has been durably influenced by heterogeneous processes which took place on stratospheric aerosols significantly enhanced following strong volcanic eruption of Mt Pinatubo (Philippines) in June 1991. The above-mentioned topics, complementary findings resulting from the study of the evolution of inorganic fluorine in the stratosphere, as well as comparisons other observational data bases and 2D model predictions are essentially discussed in Chapter 4. Before, Chapter 1 briefly reviews physical and chemical properties of the Earth atmosphere, and processes that control the state and erosion of stratospheric ozone. Individual contributions of chlorinated source gases to the CCly budget and their temporal evolution to the latter, inventory of Cly species, phase out schedule of chemical compounds covered by the Montreal Protocol and its Amendments and Adjustments are given in Chapter 2. Chapter 3 deals with instrumentation and data processing descriptions used to produce the geophysical data sets exploited in the main chapter of this work. [less ▲]

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See detailThe NOy budget above Jungfraujoch: long-term evolution, family partition and model comparison
Demoulin, Philippe ULg; Mahieu, Emmanuel ULg; Zander, Rodolphe ULg et al

in Abstracts presented at the NDSC 2001 Symposium: Celebrating 10 years of atmospheric research (2001)

Based on high-resolution solar spectra recorded with FTIR instruments at the University of Liège laboratory located at the Jungfraujoch NDSC station (Swiss Alps, 46.5ºN, 8ºE, altitude 3580 m), the most ... [more ▼]

Based on high-resolution solar spectra recorded with FTIR instruments at the University of Liège laboratory located at the Jungfraujoch NDSC station (Swiss Alps, 46.5ºN, 8ºE, altitude 3580 m), the most important constituents making up the NOy family have been measured consistently since the mid-1980s. They include HNO3, NO, NO2 and ClONO2, which are analyzed in terms of their vertical column abundances above the site. Related trends have been determined and assessed statistically. Among these, only ClONO2 and NO2 reveal significant long-term trends. The combined column evaluation of NOy indicates a rate of change equal to (0.1+/-0.2) %/year, thus statistically undefined and barely consistent with the evolution of the source gas N2O. Trends derived from the observations will be compared critically with those deduced from a long-term run of a 2-D stratospheric model developed at the University of Oslo. The model includes full gaseous chemistry, PSCs and sulfate particles, which vary from year to year. Comparisons with similar data found in the literature are also discussed. [less ▲]

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