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See detailProfiles of stratospheric chlorine nitrate (ClONO2) from atmospheric trace molecule spectroscopy/ATLAS 1 infrared solar occultation spectra
Rinsland, Curtis P.; Gunson, M. R.; Abrams, M. C. et al

in Journal of Geophysical Research (1994), 99(D9), 18895-18900

Stratospheric volume mixing ratio profiles of chlorine nitrate (ClONO2) have been retrieved from 0.01-cm−1 resolution infrared solar occultation spectra recorded at latitudes between 14°N and 54°S by the ... [more ▼]

Stratospheric volume mixing ratio profiles of chlorine nitrate (ClONO2) have been retrieved from 0.01-cm−1 resolution infrared solar occultation spectra recorded at latitudes between 14°N and 54°S by the atmospheric trace molecule spectroscopy Fourier transform spectrometer during the ATLAS 1 shuttle mission (March 24 to April 2, 1992). The results were obtained from nonlinear least squares fittings of the ClONO2 v 4 band Q branch at 780.21 cm−1 with improved spectroscopic parameters generated on the basis of recent laboratory work. The individual profiles, which have an accuracy of about ±20%, are compared with previous observations and model calculations. [less ▲]

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See detailIncrease of carbonyl fluoride (COF2) in the stratosphere and its contribution to the 1992 budget of inorganic fluorine in the upper stratosphere
Zander, Rodolphe ULg; Rinsland, Curtis P.; Mahieu, Emmanuel ULg et al

in Journal of Geophysical Research (1994), 99(D8), 16737-16743

Volume mixing ratio profiles of COF2 have been derived through most of the stratosphere between 30°N and 54°S from series of 0.01-cm−1 resolution infrared solar spectra recorded in the occultation mode by ... [more ▼]

Volume mixing ratio profiles of COF2 have been derived through most of the stratosphere between 30°N and 54°S from series of 0.01-cm−1 resolution infrared solar spectra recorded in the occultation mode by the atmospheric trace molecule spectroscopy (ATMOS) instrument during the ATLAS 1 space shuttle mission of March–April 1992. When compared with similar results obtained from the ATMOS/Spacelab 3 mission of April–May 1985, the cumulative increase in the burden of COF2 in the middle and upper stratosphere was found to be 67% for that 7-year time interval. By combining a subset of these COF2 results with upper stratospheric concentrations of HF also derived from the ATMOS observations, it was further found that the budget of inorganic fluorine above 35 km altitude increased by (60 ± 10) % over the 1985–1992 time interval, which corresponds to an average exponential rate of increase of (6.7 ± 1.1) % yr−1, or a linear rate of increase referenced to 1985 of (8.5 ± 1.3) % yr−1 at the 1σ confidence level. The total inorganic F atom volume mixing ratio found in the upper stratosphere for 1985 and 1992 and the increase during this period mirror the rise in man-made fluorine-bearing compounds at the ground during the early to mid 1980s. This demonstrates the negligible impact of natural sources of fluorine, in particular volcanic activity, on the observed change of F in the upper stratosphere. Implications of the present findings and comparison with model results are discussed. [less ▲]

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See detailSECULAR TREND AND SEASONAL VARIABILITY OF THE COLUMN ABUNDANCE OF N2O ABOVE THE JUNGFRAUJOCH STATION DETERMINED FROM IR SOLAR SPECTRA
Zander, Rodolphe ULg; EHHALT, D. H.; RINSLAND, Curtis P. et al

in Journal of Geophysical Research (1994), 99(D8), 16745-16756

Infrared solar spectra recorded at the International Scientific Station of the Jungfraujoch (3580 m altitude), Switzerland, in 1950-1951 and from 1984 to 1992 have been analyzed to determine vertical ... [more ▼]

Infrared solar spectra recorded at the International Scientific Station of the Jungfraujoch (3580 m altitude), Switzerland, in 1950-1951 and from 1984 to 1992 have been analyzed to determine vertical column abundances of nitrous oxide (N2O) above the station. The best fit to the relatively dense set of measurements made between 1984 and 1992 indicates a mean exponential rate of increase equal to 0.36 +/- 0.06% yr-1 (1 sigma) and a seasonal modulation of 7.2% peak to peak, the minimum occurring at the end of the winter and the maximum in early September. The column abundances for April of the years 1951, 1984, and 1992 were found equal to 3.49 x 10(18), 3.76 x 10(18), and 3.87 x 10(18) molecules cm-2, respectively; they translate into N2O concentrations at the altitude of the Jungfraujoch equal to 275, 296, and 305 parts per billion by volume. These results indicate that the exponential rate of increase for 1951-1984 was equal to 0.23 +/- 0.04% yr-1 (1 sigma), thus substantially lower than for the 1984-1992 time interval and that the so-called preindustrial levels of N2O pertained until 1951 with most of the increase in atmospheric N2O occurring thereafter. [less ▲]

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See detailMonitoring of the atmospheric burdens of CH4, N2O, CO, CHCIF2 and CF2Cl2 above Central Europe during the last decade
Zander, Rodolphe ULg; Demoulin, Philippe ULg; Mahieu, Emmanuel ULg

in Environmental Monitoring & Assessment (1994, May), 31(1-2), 203-209

Based on high spectral resolution infrared solar observations made at the International Scientific Station of the Jungfraujoch, Switzerland, total vertical column abundances of 18 atmospheric gases have ... [more ▼]

Based on high spectral resolution infrared solar observations made at the International Scientific Station of the Jungfraujoch, Switzerland, total vertical column abundances of 18 atmospheric gases have been monitored routinely since 1984. The observed temporal evolutions in the columns of CH4, N2O, CO, CHClF2 (HCFC-22) and CF2Cl2 (CFC-12) are reported here as typical examples of this monitoring effort which is conducted within the frame of ''Global Change'' and ''Network for the Detection of Stratospheric Change'' programs. [less ▲]

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See detailHeterogeneous conversion of N2O5 to HNO3 in the post-Mount Pinatubo eruption stratosphere
Rinsland, Curtis P.; Gunson, Michaël R.; Abrams, M. C. et al

in Journal of Geophysical Research (1994), 99(D4), 8213-8219

Simultaneous stratospheric volume mixing ratio (VMR) profiles of dinitrogen pentoxide (N2O5) and nitric acid (HNO3) at sunrise between 25-degrees-N and 15-degrees-S latitude and profiles of HNO3 at sunset ... [more ▼]

Simultaneous stratospheric volume mixing ratio (VMR) profiles of dinitrogen pentoxide (N2O5) and nitric acid (HNO3) at sunrise between 25-degrees-N and 15-degrees-S latitude and profiles of HNO3 at sunset between 42-degrees-S and 53-degrees-S latitude have been derived from 0.01 cm-1 resolution infrared solar occultation spectra recorded 9 1/2 months after the massive eruption of the Mount Pinatubo volcano in the Philippine Islands. The measurements were obtained by the atmospheric trace molecule spectroscopy (ATMOS) Fourier transform spectrometer during the ATLAS 1 shuttle mission (March 24 to April 2, 1992). The measured HNO3 VMRs are higher at all altitudes and latitudes than corresponding values measured by the limb infrared monitor of the stratosphere (LIMS) instrument during the same season in 1979, when the aerosol loading was near background levels. The largest relative increase in the HNO3 VMR occurred near the equator at 30-km altitude, where the ATMOS/ATLAS 1 values are about a factor of 2 higher than the LIMS measurements. Two-dimensional model calculations show that the increase in HNO3 and the ATMOS/ATLAS 1 measurement of a steep decrease in the N2O5 VMR below 30 km can be explained by the enhanced conversion of N2O5 to HNO3 on the surfaces of the Mount Pinatubo sulfate aerosols. Our profile results demonstrate the global impact of the N2O5 + H2O --> 2HNO3 heterogeneous reaction in altering the partitioning of stratospheric odd nitrogen after a major volcanic eruption. [less ▲]

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See detailSECULAR EVOLUTION OF THE VERTICAL COLUMN ABUNDANCES OF CHCLF2 (HCFC-22) IN THE EARTH'S ATMOSPHERE INFERRED FROM GROUND-BASED IR SOLAR OBSERVATIONS AT THE JUNGFRAUJOCH AND AT KITT-PEAK, AND COMPARISON WITH MODEL-CALCULATIONS
Zander, Rodolphe ULg; Mahieu, Emmanuel ULg; Demoulin, Philippe ULg et al

in Journal of Atmospheric Chemistry (1994), 18(2), 129-148

Series of high-resolution infrared solar spectra recorded at the International Scientific Station of the Jungfraujoch, Switzerland, between 06/1986 and 11/1992, and at Kitt Peak National Observatory ... [more ▼]

Series of high-resolution infrared solar spectra recorded at the International Scientific Station of the Jungfraujoch, Switzerland, between 06/1986 and 11/1992, and at Kitt Peak National Observatory, Tucson, Arizona (U.S.A.), from 12/1980 to 04/1992, have been analyzed to provide a comprehensive ensemble of vertical column abundances of CHClF2 (HCFC-22; Freon-22) above the European and the North American continents. The columns were derived from nonlinear least-squares curve fittings between synthetic spectra and the observations containing the unresolved 2nu6 Q-branch absorption of CHClF2 at 829.05 cm-1. The changes versus time observed in these columns were modeled assuming both an exponential and a linear increase with time. The exponential rates of increase at one-sigma uncertainties were found equal to (7.0 +/- 0.35)%/yr for the Junfraujoch data and (7.0 +/- 0.23)%/yr for the Kitt Peak data. The exponential trend of 7.0%/yr found at both stations widely separated in location can be considered as representative of the global increase of the CHClF2 burden in the Earth's atmosphere during the period 1980 to 1992. When assuming two realistic vertical volume mixing ratio profiles for CHClF2 in the troposphere, one quasi constant and the other decreasing by about 13% from the ground to the tropopause, the concentrations for mid-1990 were found to lie between 97 and 111 pptv (parts per trillion by volume) at the 3.58 km altitude of the Jungfraujoch and between .97 and 103 pptv at Kitt Peak, 2.09 km above sea level. Corresponding values derived from calculations using a high vertical resolution-2D model and recently compiled HCFC-22 releases to the atmosphere, were equal to 107 and 105 pptv, respectively, in excellent agreement with the measurements. The model calculated lifetime of CHClF2 was found equal to 15.6 years. The present results are compared critically with similar data found in the literature. On average, the concentrations found here are lower by 15-20% than those derived from in situ investigations; this difference cannot be explained by the absolute uncertainty of +/- 11% assigned presently to the infrared remote measurements. [less ▲]

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See detailATMOS ATLAS-1 MEASUREMENTS OF SULFUR-HEXAFLUORIDE (SF6) IN THE LOWER STRATOSPHERE AND UPPER TROPOSPHERE
Rinsland, C. P.; Gunson, M. R.; Abrams, M. C. et al

in Journal of Geophysical Research (1993), 98(D11), 20491-20494

Vertical profiles of sulfur hexafluoride (SF6) in the lower stratosphere and upper troposphere have been retrieved from 0.01-cm-1 resolution infrared solar occultation spectra recorded by the Atmospheric ... [more ▼]

Vertical profiles of sulfur hexafluoride (SF6) in the lower stratosphere and upper troposphere have been retrieved from 0.01-cm-1 resolution infrared solar occultation spectra recorded by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer during the ATLAS (Atmospheric Laboratory for Applications and Science) 1 shuttle mission of March 24 to April 2, 1992. Based on measurements of the unresolved absorption by the SF6 nu3 band Q branch at 947.9 cm-1, average SF6 volume mixing ratios and 1-sigma uncertainties of 3.20 +/- 0.54 parts per trillion by volume (pptv; 10(-12) ppv) at 200 mbar (approximately 11.8 km) declining to 2.86 +/- 0.29 pptv at 100 mbar (approximately 16.2 km) and 1.95 +/- 0.50 pptv at 30 mbar (approximately 23.9 km) have been retrieved. The profiles show no obvious dependence with latitude over the range of the measurements (eight occultations spanning 28-degrees-S to 54-degrees-S). Assuming an exponential growth model and applying a correction for the interhemispheric concentration difference, an average SF6 rate of increase of 8.7 +/- 2.2% per year, 2 sigma, between 12 and 18 km has been derived by fitting the present measurements, ATMOS measurements from the April-May 1985 Spacelab 3 mission, and balloon-borne IR measurements obtained in March 1981 and June 1988. [less ▲]

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See detailRecent atmospheric spectroscopy applications at the Jungfraujoch and related problems
Demoulin, Philippe ULg; Mahieu, Emmanuel ULg; Mélen, Francine et al

in Proceedings of Atmospheric Spectroscopy Applications, ASA Reims 1993, September 8-10 (1993)

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See detailSpectroscopic Measurements of Atmospheric Changes (SMAC), Belgian Impulse Programme GLOBAL CHANGE
Delbouille, L.; Roland, G.; Zander, Rodolphe ULg et al

in Proceedings of the Symposium of Belgian Impulse Programme "Global Change" (1993)

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See detailMonitoring of statospheric changes at the Jungfraujoch station by high-resolution infrared solar observations in support of the Network for Detection of Stratospheric Change (NDSC)
Zander, Rodolphe ULg; Mahieu, Emmanuel ULg; Demoulin, Philippe ULg

in Chanin, M.-L. (Ed.) The role of the stratosphere in global change (1993)

Infrared remote sensing observations from the ground, using the sun as source of radiation, constitute a powerful tool for monitoring the state of our environment. The observational effort carried out at ... [more ▼]

Infrared remote sensing observations from the ground, using the sun as source of radiation, constitute a powerful tool for monitoring the state of our environment. The observational effort carried out at the International Scientific Station of the Jungfraujoch, Switzerland, is used in this paper as a typical example to stress out the performances achievable by that technique. When based on high spectral resolution and high signal-to-noise observations, it can overcome the bulk of the absorption produced by gases with high concentration in the troposphere and contribute efficiently to the quantification and monitoring of trace gases predominantly concentrated in the stratosphere. [less ▲]

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See detailGROUND-BASED INFRARED MEASUREMENTS OF CARBONYL SULFIDE TOTAL COLUMN ABUNDANCES - LONG-TERM TRENDS AND VARIABILITY
RINSLAND, C. P.; Zander, Rodolphe ULg; Mahieu, Emmanuel ULg et al

in Journal of Geophysical Research (1992), 97(D5), 5995-6002

Total vertical column abundances of carbonyl sulfide (OCS) have been derived from time series of high-resolution infrared solar absorption spectra recorded at the National Solar Observatory McMath solar ... [more ▼]

Total vertical column abundances of carbonyl sulfide (OCS) have been derived from time series of high-resolution infrared solar absorption spectra recorded at the National Solar Observatory McMath solar telescope facility on Kitt Peak (altitude 2.09 km, latitude 31.9-degrees-N, longitude 111.6-degrees-W), southwest of Tucson, Arizona, and at the International Scientific Station of the Jungfraujoch (altitude 3.58 km, latitude 46.5-degrees-N, longitude 8.0-degrees-E), in the Swiss Alps. The analysis of both data sets is based on nonlinear least squares spectral fittings of narrow intervals centered on lines of the intense nu-3 band of OCS, the P(37) transition at 2045.5788 cm-1 and the P(15) transition at 2055.8609 cm-1, with a consistent set of spectroscopic line parameters. The Kitt Peak measurements, recorded on 30 different days between May 1977 and March 1991, show a 10% peak-to-peak seasonal cycle with a summer maximum and a winter minimum and a trend in the total column abundance equal to (0.1 +/- 0.2)% yr-1, 2-sigma. Jungfraujoch solar spectra recorded on 67 different days between October 1984 and April 1991 have been analyzed. The fitted trend in the Jungfraujoch total columns, (-0.1 +/- 0.5)% yr-1, 2-sigma, is consistent with the Kitt Peak trend results within the errors. The Jungfraujoch total columns show a more complex seasonal variation than noted in the Kitt Peak data. The mean of the daily averaged total columns, 8.44 x 10(15) molecules cm-2 above Kitt Peak and 6.41 x 10(15) molecules cm-2 above the Jungfraujoch station, correspond respectively to mean tropospheric mixing ratios of 0.54 +/- 0.04 and 0.52 +/- 0.04 parts per billion by volume; these values are consistent with previously reported remote and in situ measurements. Taken together, the results from the two sites indicate that there has been no significant change in the OCS total column abundance at northern mid-latitudes over the last decade. [less ▲]

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See detailThe 1985 chlorine and fluorine inventories in the stratosphere based on atmos observations at 30-degrees north latitude
Zander, Rodolphe ULg; Gunson, Michael R.; Farmer, Crofton B. et al

in Journal of Atmospheric Chemistry (1992), 15(2), 171-186

The set of high-resolution infrared solar observations made with the Atmospheric Trace Molecule Spectroscopy (ATMOS) - Fourier transform spectrometer from onboard Spacelab 3 (30 April-1 May 1985) has been ... [more ▼]

The set of high-resolution infrared solar observations made with the Atmospheric Trace Molecule Spectroscopy (ATMOS) - Fourier transform spectrometer from onboard Spacelab 3 (30 April-1 May 1985) has been used to evaluate the total budgets of the odd chlorine and fluorine chemical families in the stratosphere. These budgets are based on volume mixing ratio profiles measured for HCl, HF, CH3Cl, ClONO2, CCl4, CCl2F2, CCl3F, CHClF2, CF4, COF2, and SF6, near 30-degrees north latitude. When including realistic concentrations for species not measured by ATMOS, i.e., the source gases CH3CCl3, and C2F3Cl3 below 25 km, and the reservoirs ClO, HOCl and COFCl between 15 and 40 km (five gases actually measured by other techniques), the 30-degrees-N zonal 1985 mean total mixing ratio of chlorine, Cl, was found to be equal to (2.58 +/- 0.10) ppbv (parts per billion by volume) throughout the stratosphere, with no significant decrease near the stratopause. The results for total fluorine indicate a slight, but steady, decrease of its volume mixing ratio with increasing altitude, around a mean stratospheric value of (1.15 +/- 0.12) ppbv. Both uncertainties correspond to one standard deviation. These mean springtime 1985 stratospheric budgets are commensurate with values reported for the tropospheric Cl and F concentrations in the early 1980s, when allowance is made for the growth rates of their source gases at the ground and the time required for tropospheric air to be transported into the stratosphere. The results are discussed with emphasis on conservation of fluorine and chlorine and the partitioning among source, sink, and reservoir gases throughout the stratosphere. [less ▲]

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See detailInfrared Spectroscopic Measurements of the Vertical Column Abundance of Sulfur Hexafluoride, SF6, From the Ground
Zander, Rodolphe ULg; Rinsland, C.P.; Demoulin, Philippe ULg

in Journal of Geophysical Research (1991), 96(D8), 15447-15454

The unresolved v3 band Q branch of sulfur hexafluoride, SF6, at 947.9 cm-1 has been identified and quantitatively analyzed in series of high-quality infrared solar spectra recorded at the International ... [more ▼]

The unresolved v3 band Q branch of sulfur hexafluoride, SF6, at 947.9 cm-1 has been identified and quantitatively analyzed in series of high-quality infrared solar spectra recorded at the International Scientific Station of the Jungfraujoch, Switzerland, and at the National Solar Observatory facility on Kitt Peak in Arizona. Series of monthly mean total vertical column abundances of SF6 above both stations, deduced from that feature with line-by-line nonlinear least squares fitting methods, are reported over the time intervals from June 1986 to June 1990 for the Jungfraujoch and from March 1981 to June 1990 for Kitt Peak. Assuming an exponential growth model for fitting these series of measurements, it is found that the vertical column abundances have increased at mean rates of 6.9 +- 2.8 %/yr above the Jungfraujoch (calculated columns of 2.99 x 10E13 molecules/cm2 in June 1986 and 3 94 x 10E13 molecules/cm2 in June 1990) and 6.6 +- 7.2 %/yr above Kitt Peak (calculated columns equal to 2.97 x 10E13 molecules/cm2 in June 1981 and 5.38 x 10E13 molecules/cm2 in June 1990), the uncertainties corresponding to 2 sigma confidence levels. These results are further discussed within the context of variability and compared with previously published measurements. [less ▲]

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See detailDetermination of Absolute Strengths of N2 Quadrupole Lines From High-Resolution Ground-based IR Solar Observations
Demoulin, Philippe ULg; Farmer, C.B.; Rinsland, C.P. et al

in Journal of Geophysical Research (1991), 96(D7), 13003-13008

High-resolution, high signal-to-noise ratio, solar absorption spectra recorded with a Fourier transform spectrometer at the International Scientific Station of the Jungfraujoch, Switzerland, have been ... [more ▼]

High-resolution, high signal-to-noise ratio, solar absorption spectra recorded with a Fourier transform spectrometer at the International Scientific Station of the Jungfraujoch, Switzerland, have been analyzed to determine the strengths of several lines belonging to the S branch of the N2 (1-0) electric quadrupole vibration-rotation band centered at 2329.9168 cm-1. The method which was applied here was based on equivalent width measurements of lines observed over a broad range of air masses; extrapolation of these measurements to zero air mass gave the line strengths for the transitions S7 to S10, independent of half widths, an ambiguity unavoidable with the use of curve-fitting techniques. The resulting absolute accuracies of the line strengths derived here, estimated to be better than +-2.5% for S8, +-2.6% for S10, +-3.4% for S9, and +-5.1% for S7, are due largely to the high quality and quantity of the spectra retained in this analysis and the accuracy with which the observation conditions are known. An important application of the improved values for these N2 transitions, which have low initial ground state energies, is the direct determination of the line-of-sight atmospheric air masses associated with remotely sensed infrared spectroscopic observations. Positions of the N2 transitions studied here have further been redetermined with an absolute accuracy better than 0.0002 cm-1. [less ▲]

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See detailGround-Based Infrared Measurements of HNO3 Total Column Abundances: Long-Term Trend and Variability
Rinsland, C.P.; Zander, Rodolphe ULg; Demoulin, Philippe ULg

in Journal of Geophysical Research (1991), 96(D5), 9379-9389

The long-term trend and variability of the total column amount of atmospheric nitric acid (HNO3) have been investigated based on time series of infrared solar absorption spectra recorded at two remote ... [more ▼]

The long-term trend and variability of the total column amount of atmospheric nitric acid (HNO3) have been investigated based on time series of infrared solar absorption spectra recorded at two remote high-altitude sites, the International Scientific Station of the Jungfraujoch (ISSJ) in the Swiss Alps (altitude 3.6 km, latitude 46.5°N, longitude 8.0°E) and the National Solar Observatory McMath solar telescope facility on Kitt Peak (altitude 2.1 km, latitude 31.9°N, longitude 111.6°W), southwest of Tucson, Arizona. The HNO3 v5 band Q branch at 879.1 cm-1 and three P branch manifolds near 869 cm-1 were analyzed using a nonlinear least squares spectral fitting technique and a consistent set of spectroscopic line parameters. The ISSJ measurements evaluated in the present work consist of two solar spectra recorded with a grating spectrometer in June 1951 and a set of observations obtained with a high-resolution Fourier transform spectrometer between June 1986 and June 1990. The modern ISSJ measurements show a ~20% peak-to-peak amplitude seasonal cycle with a winter maximum superimposed on significant variability and a summer minimum; the June results from 1986 to 1990 are both higher and lower than the two retrieved June 1951 HNO3 total column amounts. The fitted trend, (-0.16 +- 0.50) %/yr, 2 sigma, indicates that there has been no detectable change in the HNO3 total column over the last 4 decades. The Kitt Peak measurements, recorded with a high-resolution Fourier transform spectrometer between December 1980 and June 1990, also show marked variability in the HNO3 total column, but in contrast to the ISSJ measurements, no obvious seasonal cycle is observed. The deduced trend in the total column above Kitt Peak, (-0.8 +- 1.6) %/yr, 2 sigma, is consistent with the ISSJ time series of measurements, in that no significant HNO3 long-term trend has been found. The sets of measurements from the two sites are compared with each other and with previously published results, with emphasis on the reported variability of HNO3 and the changes in the HNO3 total column with season and latitude. [less ▲]

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See detailSeasonal Cycle and Secular Trend of the Total and Tropospheric Column Abundance of Ethane Above the Jungfraujoch
Ehhalt, D.H.; Schmidt, U.; Zander, Rodolphe ULg et al

in Journal of Geophysical Research (1991), 96(D3), 4985-4994

Total column abundances of ethane (C2H6) above the Jungfraujoch Station, Switzerland, 3.58-km altitude, have been deduced from infrared solar spectra recorded in 1951 and from 1984 to 1988. The results ... [more ▼]

Total column abundances of ethane (C2H6) above the Jungfraujoch Station, Switzerland, 3.58-km altitude, have been deduced from infrared solar spectra recorded in 1951 and from 1984 to 1988. The results were derived from the spectroscopic analysis of the v7 band PQ3, PQ1, and RQ0 subbranches of C2H6 near 2976.8, 2983.4, and 2986.7 cm-1, respectively. The 1984-1988 results obtained from more than 300 observations at 0.005 cm-1 resolution show a definite seasonal variation in the total vertical column abundance of that gas, with a maximum of (1.43 +- 0.03) x 10E16 molecules/cm2 during March and April and a minimum in the fall. The corresponding C2H6 mixing ratio in the free troposphere was derived to 1.53 +- 0.14 ppb in early April; the ratio of maximum to minimum C2H6 concentration in the troposphere was found to be 1.88 +- 0.12. From the analysis of the same spectral features observed in March and April 1951, we have deduced a total vertical column abundance of (1.09 +- 0.10) x 10E16 molecules/cm2. Assuming an exponential increase with time and correcting for a small decrease in the stratospheric amount of C2H6 due to the man-induced increase in stratospheric chlorine, we obtain a secular trend in the tropospheric burden above the Jungfraujoch equal to (0.85 +- 0.3)%/yr. It is argued that this trend is valid for the entire northern hemisphere. [less ▲]

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See detailVertical Column Abundances and Seasonal Cycle of Acetylene, C2H2, above the Jungfraujoch Station, Derived from IR Solar observations
Zander, Rodolphe ULg; Rinsland, C.P.; Ehhalt, D.H. et al

in Journal of Atmospheric Chemistry (1991), 13

Monthly mean total vertical column abundances of acetylene have been determined from series of infrared solar spectra recorded at the Jungfraujoch station, Switzerland, between June 1986 and April 1991 ... [more ▼]

Monthly mean total vertical column abundances of acetylene have been determined from series of infrared solar spectra recorded at the Jungfraujoch station, Switzerland, between June 1986 and April 1991. The data have been obtained by nonlinear least-squares fittings of the v5 band R19 transition of C2H2 at 776.0818 cm-1. The average of 22 monthly mean total vertical columns of C2H2 retrieved during that time interval of almost 5 years was found to be equal to (1.81 +- O.12) X 1OE15 molec/cm2, which corresponds to an average mixing ratio of (0.22 +- O.013) ppbv (parts per billion by volume) in a troposphere extending from the altitude of the station (3.58 km), up to 10.5 km. Despite the large variability found from year to year, a least-squares sine fit to the data reveals a seasonal variation with an amplitude of about +- 40 % of the mean; the maximum occurs during mid-winter and the minimum in the summer. The present results are compared critically with similar in-situ data found in the literature. A sinusoidal fit to ail such free troposphere measurements made in-situ between 30° N and 60° N indicates good agreement in shape and phase with the seasonal variation derived above the Jungfraujoch, but their average column abundance, 2.3 X lOE15 molec/cm2, is about 30 % higher; this difference is explained on the basis of non-upwelling meteorological conditions generally prevailing during ground-based remote solar observations. [less ▲]

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See detailInfrared remote sensing of atmosphere at the Jungfraujoch station - Evidence for global changes
Zander, Rodolphe ULg; Demoulin, Philippe ULg

in Putkonen, Jyri (Ed.) Proceedings of the IGARSS '91 - Remote Sensing, Global Monitoring for Earth Management, Espoo, Finland, June 3-6, 1991 (1991)

The thread imposed upon the earth"s atmosphere by anthropogenic activities is becoming well documented. Analyses of infrared solar observations carried out at the International Scientific Station of the ... [more ▼]

The thread imposed upon the earth"s atmosphere by anthropogenic activities is becoming well documented. Analyses of infrared solar observations carried out at the International Scientific Station of the Jungfraujoch, Switzerland, in 1950-51 and more intensively since the late 1970s have contributed to that documentation. This paper summarizes original findings arrived at so far and raises the need for intensive and coordinated observational programs during the 1990s. [less ▲]

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See detailLe laboratoire de physique solaire et atmosphérique du Jungfraujoch
Delbouille, Luc; Roland, Ginette; Zander, Rodolphe ULg et al

in Pyle, J.A.; Harris, N.R.P. (Eds.) Proceedings of the First European Workshop on Polar Stratospheric Ozone Research, 3-5 October 1990, Schliersee, Bavaria, FRG (1990)

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See detailSecular Increase of the Vertical Column Abundance of Methane Derived From IR Solar Spectra Recorded at the Jungfraujoch Station
Zander, Rodolphe ULg; Demoulin, Philippe ULg; Ehhalt, D.H. et al

in Journal of Geophysical Research (1989), 94(D8), 11029-11039

Using all of the pertinent infrared solar spectra recorded at the Jungfraujoch Station, Switzerland, in 1951, 1975, and in 1984-1987, the increase of the vertical column abundance of methane, CH4, above ... [more ▼]

Using all of the pertinent infrared solar spectra recorded at the Jungfraujoch Station, Switzerland, in 1951, 1975, and in 1984-1987, the increase of the vertical column abundance of methane, CH4, above that station has been reevaluated. The results are based on equivalent widths measurements of both the R0 and the R5 transitions of the 2v3 band of CH4 at 6015.66 and 6067.09 cm-1 and on the CH4-v3 band absorption characteristics between 2905.0 and 2908.8 cm-1. The data between 1984 and 1987 provide a full seasonal cycle. They demonstrate a significant annual variation in the column abundance of CH4 of +- 10% around the mean. They also show variability on shorter time scales. The mean cumulative rate of increase of the total vertical column abundance of CH4 above the Jungfraujoch is found to be (0.7 +- 0.1) %/yr between 1951 and 1986. Using a realistic CH4 concentration profile throughout the troposphere and the stratosphere, we deduce volume mixing ratios at the altitude of the Jungfraujoch, equal to 1.28 +- 0.08 and 1.64 +- 0.09 ppm, for 1951 and for 1985-1987, respectively. [less ▲]

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