ATMOS/ATLAS-3 measurements of stratospheric chlorine and reactive nitrogen partitioning inside and outside the November 1994 Antarctic vortex

in Geophysical Research Letters (1996), 23(17), 2365-2368

Partitioning between HCl and ClONO2 and among the main components of the reactive nitrogen family (NO, NO2, HNO3, ClONO2, N2O5, and HO2NO2) has been studied inside and outside the Antarctic stratospheric ... [more ▼]

Partitioning between HCl and ClONO2 and among the main components of the reactive nitrogen family (NO, NO2, HNO3, ClONO2, N2O5, and HO2NO2) has been studied inside and outside the Antarctic stratospheric vortex based on ATMOS profiles measured at sunrise during the 3-12 November 1994 ATLAS-3 Shuttle mission. Elevated mixing ratios of HCl in the lower stratosphere with a peak of similar to 2.9 ppbv (10(-9) parts per volume) were measured inside the vortex near 500 K potential temperature (similar to 19 km). Maximum ClONO2 mixing ratios of similar to 1.2, similar to 1.4, and similar to 0.9 ppbv near 700 K (similar to 25 km) were measured inside, at the edge, and outside the vortex, respectively. Model calculations reproduce the higher levels of HCl and NOx (NO + NO2) inside the lower stratospheric vortex both driven by photochemical processes initiated by low O3. The high HCl at low O3 results from chemical production of HCl via the reaction of enhanced Cl with CH4, limited production of ClONO2, and the descent of inorganic chlorine from higher altitudes. [less ▲]

ClONO2 total vertical column abundances above the Jungfraujoch Station, 1986-1994: Long-term trend and winter-spring enhancements

in Journal of Geophysical Research (1996), 101(D2), 3891-3899

Total vertical column abundances of chlorine nitrate (ClONO2) have been retrieved from 0.006 cm(-1) resolution solar absorption spectra recorded at the International Scientific Station of the Jungfraujoch ... [more ▼]

Total vertical column abundances of chlorine nitrate (ClONO2) have been retrieved from 0.006 cm(-1) resolution solar absorption spectra recorded at the International Scientific Station of the Jungfraujoch (ISSJ) in the Swiss Alps (altitude 3.58 km, latitude 46.5 degrees N, longitude 8.0 degrees E) on 105 days between June 1986 and November 1994. The analysis is based on spectral fittings of the ClONO2 nu(4) band Q branch at 780.21 cm(-1) and the interferences occurring in the same spectral region. The ISSJ measurements show a regular long-term increase in the ClONO2 column with an occasional factor of 2 to 3 enhancements during the midwinter to early spring. Excluding data from this time of the year, the ISSJ database reflects a linear rate of increase and la uncertainty equal to (4.0 +/- 0.7)% yr(-1) referenced to 1990.0. The corresponding ClONO2 total vertical columns for mid-1986 and mid-1994 are equal to 0.92 and 1.26 x 10(15) molecules cm(-2), respectively. The high ClONO2 columns and high HF/HCl column ratios sometimes measured during winter indicate the occasional presence of chemically processed air above the station. This is corroborated by trajectories calculated for the stratospheric air masses sounded on these occasions. [less ▲]

Trends of OCS, HCN, SF6, CHClF2, (HCFC-22) in the lower stratosphere from 1985 and 1994 atmospheric trace molecule spectroscopy experiment measurements near 30 degrees N latitude

in Geophysical Research Letters (1996), 23(17), 2349-2352

Volume mixing ratio (VMR) profiles of OCS, HCN, SF6, and CHClF2 (HCFC-22) have been measured near 30 degrees N latitude by the Atmospheric Trace Molecule Spectroscopy Fourier transform spectrometer during ... [more ▼]

Volume mixing ratio (VMR) profiles of OCS, HCN, SF6, and CHClF2 (HCFC-22) have been measured near 30 degrees N latitude by the Atmospheric Trace Molecule Spectroscopy Fourier transform spectrometer during shuttle flights on 29 April-6 May 1985 and 3-2 November 1994. The change in the concentration of each molecule in the lower stratosphere has been derived for this 9 1/2-year period by comparing measurements between potential temperatures of 395 to 800 K (similar to 17 to 30 km altitude) relative to simultaneously measured values of the long-lived tracer N2O. Exponential rates of increase inferred for 1985-to-1994 from these comparisons are (0.1 +/- 0.4)% yr(-1) for OCS, (1.0 +/- 1.0)% yr(-1) for HCN, (8.0+/-0.7)% yr(-1) for SF6, and (8.0 +/- 1.0)% yr(-1) for CHClF2 (HCFC-22), 1 sigma. The lack of an appreciable trend for OCS suggests the background (i.e., nonvolcanic) source of stratospheric aerosol was the same during the two periods. These results are compared with trends reported in the literature. [less ▲]

APRIL 1993 ARCTIC PROFILES OF STRATOSPHERIC HCL, CLONO2, AND CCL2F2 FROM ATMOSPHERIC TRACE MOLECULE SPECTROSCOPY ATLAS 2 INFRARED SOLAR OCCULTATION SPECTRA

in Journal of Geophysical Research (1995), 100(D7), 14019-14027

Partitioning among the major components of the stratospheric odd chlorine family inside and outside of the remanent Arctic vortex has been studied on the basis of infrared solar occultation measurements ... [more ▼]

Partitioning among the major components of the stratospheric odd chlorine family inside and outside of the remanent Arctic vortex has been studied on the basis of infrared solar occultation measurements obtained by the atmospheric trace molecule spectroscopy (ATMOS) Fourier transform spectrometer during the ATLAS 2 shuttle mission (April 8-17, 1993). Profiles of hydrogen chloride (HCl) and simultaneous profiles of chlorine nitrate (ClONO2) and CFC-12 (CCl2F2) are reported for examples of in-vortex and out-of-vortex conditions. Increased ClONO2 volume-mixing ratios (VMRs) are measured in the vortex below 20 mbar (similar to 25 km altitude) with a peak ClONO2 VMR of 2.05 +/- 0.45 ppbv (10(-9) per volume) at 56 mbar (similar to 19 km altitude). The reported error correspond to la uncertainties. Simultaneous CCl2F2 and N2O measurements, combined with published empirical relations, indicate that only 0.34 +/- 0.15 ppbv, about 10% of total chlorine, was bound in organic species at the ClONO2 VMR peak in the vortex. A colocated vortex profile of HCl, referenced to simultaneous N2O VMR measurements, has been used to derive a HCl mixing ratio of 1.21 +/- 0.12 ppbv corresponding to the ClONO2 VMR peak. The internal consistency of the ATMOS measurements is demonstrated by the agreement between the total chlorine mixing ratio of 3.60 +/- 0.72 ppbv derived at the ClONO2 VMR peak in the vortex and HCl measurements of 3.37 +/- 0.37 and 3.76 +/- 0.41 ppbv at 0.56 mbar, where HCl is the only significant chlorine-bearing molecule. Outside the vortex the mixing ratio of HCl exceeds the mixing ratio of ClONO2 throughout the stratosphere. [less ▲]

Stratospheric changes monitored above the Jungfraujoch - The budgets of inorganic chlorine and fluorine since 1985.

in Proceedings of the 3d International Symposium on Polar Stratospheric Ozone Research (1995)

Profiles of stratospheric chlorine nitrate (ClONO2) from atmospheric trace molecule spectroscopy/ATLAS 1 infrared solar occultation spectra

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 ▲]

SECULAR TREND AND SEASONAL VARIABILITY OF THE COLUMN ABUNDANCE OF N2O ABOVE THE JUNGFRAUJOCH STATION DETERMINED FROM IR SOLAR SPECTRA

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 ▲]

Heterogeneous conversion of N2O5 to HNO3 in the post-Mount Pinatubo eruption stratosphere

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 ▲]

ATMOS ATLAS-1 MEASUREMENTS OF SULFUR-HEXAFLUORIDE (SF6) IN THE LOWER STRATOSPHERE AND UPPER TROPOSPHERE

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 ▲]

Monitoring of statospheric changes at the Jungfraujoch station by high-resolution infrared solar observations in support of the Network for Detection of Stratospheric Change (NDSC)

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 ▲]