An Introduction to the Mars Atmospheric Trace Molecule Occultation Spectrometer (MATMOS)
No abstract available
low resolution mapping↗
Engineering topics
Blavier, J.-F.
Publications and source records attributed to Blavier, J.-F..
Remotely Operating a Fourier Transform Spectrometer for Atmospheric Remote Sensing
This paper describes how the MkIV instrument was adapted for remote operation from the Barcroft site, where the harsh winter conditions make access difficult. Some of the main technical challenges will be discussed including, (i) operation from solar panels and batteries, (ii) cooling the detectors with LN2, (iii) instrument control and monitoring over a cellular phone, and (iv) data storage, processing and analysis. Finally, MkIV spectra measured from Barcroft and compared with those measured from JPL to highlight the advantages of the higher altitude site.
Blavier, J.-F.↗
Ground-Based Measurements of Stratospheric Composition from Mt. Barcroft, California
The MkIV is an FTIR spectrometer designed and built at JPL in the 1980's for remote sensing the composition of the Earth's atmosphere by solar absorption spectrometry. Optically, MkIV is very similar to the JPL ATMOS instrument, which flew three times on the Space Shuttle. Both use double-passed configurations with a KBr beamsplitter and compensator, in order to cover the mid-infrared. The main advantage of the MkIV is that it uses two detectors in parallel, a HgCdTe photoconductor for the long wavelengths and an InSb photodiode for the short wavelengths, allowing the entire 650 to 5650/cm region to be measured simultaneously. At a 10 kHz sampling rate, each 130 cm OPD interferogram takes 3 minutes to acquire. This paper describes how the MkIV instrument was adapted for remote operation from the Barcroft site, where the harsh winter conditions make access difficult. Some of the main technical challenges will be discussed including, (i) operation from solar panels and batteries, (ii) cooling the detectors with LN2, (iii) instrument control and monitoring over a cellular phone, and (iv) data storage, processing and analysis. Finally, MkIV spectra measured from Barcroft are compared with those measured from JPL to highlight the advantages of the higher altitude site.
Toon, G. C.↗
The Budget and Partitioning of Stratospheric Chlorine During the 1997 Arctic Summer
Volume mixing ratio profiles of HCl, HOCl, ClNO3, CH3Cl, CFC-12, and CFC-11, CCl4, HCFC-22, and CFC-113 were measured simultaneously from 9 to 38 km by the Jet Propulsion Laboratory MkIV Fourier Transform Infrared solar absorption spectrometer during two balloon flights from Fairbanks, Alaska (64.8 N), on May 8 and July 8, 1997. The altitude variation of total organic chlorine (CCl(sub y)), total inorganic chlorine (Cl(sub y)), and the nearly constant value (3.7 +/- 0.2 ppbv) of their sum (Cl(sub TOT)) demonstrates that the stratospheric chlorine species available to react with O3 are supplied by the decomposition of organic chlorinated compounds whose abundances are well quantified. Measured profiles of HCl and ClNO3 agree well with profiles found by photochemical model (differences < 10% for altitudes below 35 km) constrained by various other constituents measured by MkIV. The production of HCl by ClO + OH plays a relatively small role in the partitioning of HCl and ClNO3 for the sampled air masses. However, better agreement with the measured profiles of HCl and ClNO3 is obtained when this source of HCl is included in the model. Both the measured and calculated [ClNO3]/[HCl] ratios exhibit the expected near linear variation with [O3](sup 2)/[CH4] over a broad range of altitudes. MkIV measurements of HCl, ClNO3, and CCl(sub y) agree well with ER-2 in situ observations of these quantities for directly comparable air masses. These results demonstrate good understanding of the budget of stratospheric chlorine and that the partitioning of inorganic chlorine is accurately described by photochemical models that employ JPL97 reaction rates and production of HCl from ClO + OH for the environmental conditions encountered: relatively warm temperatures, long periods of solar illumination, and relatively low aerosol surface areas.
Sen, B.↗
The Budget and Partitioning of Stratospheric Chlorine During the 1997 Arctic Summer
Volume mixing ratio profiles of HCl, HOCl, ClNO3, CH3Cl, CFC-12, CFC-11, CCl4, HCFC-22, and CFC-113 were measured simultaneously from 9 to 38 km by the Jet Propulsion Laboratory MkIV Fourier Transform Infrared solar absorption spectrometer during two balloon flights from Fairbanks, Alaska (64.8 N), on May 8 and July 8, 1997. The altitude variation of total organic chlorine (CCly) total inorganic chlorine (Cly), and the nearly constant value (3.7 +/- 0.2 ppbv) of their sum (Cl(sub TOT)) demonstrates that the stratospheric chlorine species available to react with O3 are supplied by the decomposition of organic chlorinated compounds whose abundances are well quantified. Measured profiles of HCl and ClNO3 agree well with profiles found by photochemical model (differences < 10% for altitudes below 35 km) constrained by various other constituents measured by MkIV. The production of HCl by ClO + OH plays a relatively small role in the partitioning of HCl and ClNO3 for the sampled air masses. However, better agreement with the measured profiles of HCl and ClNO3 is obtained when this source of HCl is included in the model. Both the measured and calculated [ClNO3]/[HCl] ratios exhibit the expected near linear variation with [O3]2/[CH4] over a broad range of altitudes. MkIV measurements of HCl, ClNO3, and CC1y agree well with ER-2 in situ observations of these quantities for directly comparable air masses. These results demonstrate good understanding of the budget of stratospheric chlorine and that the partitioning of inorganic chlorine is accurately described by photochemical models that employ JPL97 reaction rates and production of HCl from ClO + OH for the environmental conditions encountered: relatively warm temperatures, long periods of solar illumination, and relatively low aerosol surface areas.
Sen, B.↗
Measurements and Model Calculations of HNO4: Implications for HO(x)
Establishing a quantitative understanding of the abundance of peroxynitric acid (HNO4) is of interest because the reaction of OH with HNO4 is believed to be a significant sink for HO(x) in the lower stratosphere and upper troposphere. We present concentration profiles of KNO4 obtained by the MkIV Fourier transform infrared spectrometer using the solar occultation technique during two flights, one at 35 N on 25 September 1993 (930925) and the other near 66 N on 7 May 1997 (970507). The observations of HN04 present an apparent dilemma: the calculated profile for HNO4 found using standard kinetics is in relatively good agreement with the mid-latitude observations, but the calculated profile for HNO4 found using the same kinetics overestimates the high-latitude summer observations by nearly a factor of two. Resolution of this dilemma is the focus of our investigation. We show that introduction into our photochemical model of a speculative long-wave (lambda greater than 650 nm) photolytic pathway for HNO4 leads to good agreement between theory and observation of HN04 for both the mid-latitude and high-latitude regions. Implications for the budget of HO(x) are also discussed.
Osterman, G. B.↗
Balloon-Borne Measurements of Stratospheric Radicals and their Precursors: Implications for the Production and Loss of Ozone
Measurements of hydrogen, nitrogen and chlorine radicals from a balloon flight on 25 September 1993 from Ft. Sumner, NM provide an opportunity to quantify photochemical production and loss of stratospheric ozone. Ozone loss rates determined using measured radical concentrations agree fairly well with loss rates calculated using a photochemical model. Catalytic cycles involving OH and HO2 are shown to dominate photochemical loss of ozone for altitudes between 44 and 50 km. Reactions involving NO and NO2 are the dominant sink for ozone between 25 and 38 km. The total ozone loss rate determined from the measurements balances calculated production rates for altitudes between 30 and 40 km. However, loss of ozone exceeds production by -35% between 42 and 50 km. The imbalance between production and loss of ozone above 42 km is larger than the uncertainty of any one of the critical kinetic parameters or species concentrations. No single adjustment to any of these parameters can simultaneously resolve the imbalance and satisfy constraints imposed by measured OH, HO2, NO2 and ClO. Our results are consistent with an additional mechanism for ozone production above 40 km other than photolysis of ground state O2.
Osterman, G. B.↗
Balloon-Borne Measurements of Stratospheric Radicals and their Precursors: Implications for the Production and Loss of Ozone
Measurements of hydrogen, nitrogen and chlorine radicals from a balloon flight on 25 September 1993 from Ft. Sumner, NM provide an opportunity to quantify photochemical production and loss of ozone. Ozone loss rates determined using radical concentrations agree fairly well with rates calculated using a constrained photochemical model.
balloons↗
Balloon-borne observations of mid-latitude hydrofluoric acid
Measurements of stratospheric hydrofluoric acid (HF) have been made by the JPL MkIV interferometer during high-altitude balloon flights. Infrared solar absorption spectra were acquired near 35 deg N at altitudes between local tropopause and 38 km. Volume mixing ratio profiles of HF derived from 4 flights (1990-93), in conjunction with simultaneously observed N2O profiles, indicate an average rate of HF increase of (5.5 +/- 0.3)% per year, in agreement with time-dependent, two-dimensional model simulations (6% per year) and ATMOS measurements.
Sen, B.↗
Latitude variations of stratospheric trace gases
We present vertical column abundances of H2O, N2O, HNO3, NO2, O3, HF, HCl, and ClNO3, determined from solar absorption spectra measured by the JPL MkIV interferometer from the NASA DC-8 aircraft. These observations, taken in 1987 and 1992, covered latitudes ranging from 85 deg S to 85 deg N. Although most gases display latitude symmetry, large asymmetries in H2O, HNO3, and O3 are apparent, which can be ascribed to processes enhanced by the colder Antarctic winter temperatures.
Toon, G. C.↗
Latitude Variations of Stratospheric Trace Gases
This paper presents observations made in 1987 and 1992, covering latitudes from 85°S to 85°N as part of the Airborne Antarctic Ozone Experiment (AAOE) in 1987 and the Airborne Arctic Stratosphere Experiment (AASE) in1992.
Trace↗
Airborne observations of the composition of the 1992 tropical stratosphere by FTIR solar absorption spectrometry
Vertical column measurements of the gaseous composition of the tropical stratosphere were made from the NASA DC-8 aircraft early in 1992. As anticipated, the burdens of the stratospheric source gases (e.g., O3, HF, HCl, ClNO3, HNO3) were reduced from their mid-latitude values due to increased uplift and photolysis. The tracers revealed considerably more uplift near the equator than the sub-tropics. For example, the HF burdens at +/- 20 deg latitude were nearly double those at 5 deg N. This, together with results obtained from other long-lived gases (e.g. N2O, CH4, CF2Cl2) indicates that volume mixing ratios found at 22 km altitude at mid-latitudes occurred at 26 km in the sub-tropics and at 30 km in the equatorial zone. This zone of uplift was symmetrical about the equator even though the sun was overhead at 20 deg S.
Toon, G. C.↗
Airborne observations of the 1992 Arctic winter stratosphere by FTIR solar absorption spectroscopy
The JPL MkIV interferometer, a Fourier Transform Infra-Red (FTIR) spectrometer designed specifically for atmospheric remote sensing, made measurements of the composition of the Arctic stratosphere in January, February and March 1992. These measurements were made from the NASA DC-8 aircraft as part of the AASE2 campaign. The data reveal that despite 5 to 6 km of subsidence inside the vortex, which more than doubled the vertically integrated column amounts (burdens) of HF and HNO3 with respect to outside the vortex, considerable losses of NO2, HCl and ClNO3 were evident by mid-January. Temporary freeze-out of HNO3 was observed only on one occasion, Jan. 19, and was accompanied by substantial reductions in HCl and ClNO3. During February and March, ClNO3 and NO2 amounts increased dramatically. HCl also recovered but at a much slower rate, so that by March ClNO3 was the major reservoir of inorganic chlorine, at times exceeding HCl by a factor 2.
Toon, G. C.↗
Infrared aircraft measurements of stratospheric composition over Antarctica during September 1987
The Jet Propulsion Laboratory Mark IV interferometer recorded high-resolution, infrared solar spectra from the NASA DC-8 aircraft during flights over Antarctica in September 1987. The atmospheric absorption features in these spectra have been analyzed to determine the burdens of O3, NO, NO2, HNO3, ClNO3, HCl, HF, CO2, CH4, N2O, HCN, CO, H2O, CFCl3, and CF2Cl2. The results show a 'collar' of high HNO3 and ClNO3 surrounding a 'core' in which the burdens of these and of HCl and NO2 are very low. Clear increases in the burdens of HF and HNO3 were observed during the course of September in the vortex core. HCl and NO2 exhibited smaller, less significant increases. The burdens of the tropospheric source gases, N2O, CH4, HCN, CFCl3, CF2Cl2, CO, and H2O, were observed to be much smaller over Antarctica than at midlatitudes. This, together with the fact that HF over Antarctica was more than double its midlatidue value, suggests that downwelling had occurred.
Toon, G. C.↗
Ground-based infrared measurements of tropospheric source gases over Antarctica during the 1986 austral spring
Simultaneous measurements of the atmospheric burdens of CH4, N2O, CO2, CF2Cl2, and CO above McMurdo Station, Antarctica, have been derived from solar absorption spectra obtained by the Jet Propulsion Laboratory high-resolution Fourier transform spectrometer. In all cases the burdens are smaller than midlatitude values. Furthermore, retrievals of N2O and CH4 indicate that the tropospheric mixing ratios were normal and that the depletion of the burdens can best be accounted for by a downward shift of the volume mixing ratio profiles by some 6-8 km. This rules out the possibility of large-scale upwelling of ozone-poor tropospheric air into the stratosphere being the cause of the Antarctic springtime ozone depletion.
Toon, G. C.↗
Infrared aircraft measurements of stratospheric composition over Antarctica during September 1987
The JPL Mark IV interferometer recorded high resolution, infared solar spectra from the NASA DC-8 aircraft during flights over Antarctica in September 1987. The atmospheric absorption features in these spectra were analyzed to determine the overburdens of O3, NO, NO2, HNO3, ClONO2, HCl, HF, CH4, N2O, CO, H2O and CFC-12. The spectra were obtained at latitudes which ranged between 64 degrees S and 86 degrees S, allowing the composition in the interior of the polar vortex to be compared with that at the edge. The latitude dependence observed for NO, HO2, HNO3, ClONO2, HCl and HF are summerized. The values at 30 deg S were observed on the ferry flight from New Zealand to Hawaii. The dashed lines connecting the two were interpolated across the region for which there are no measurements. The chemically perturbed region is seen to consist of a collar of high HNO3 and ClONO2 surrounding a core in which the overburdens of these and of HCl and NO2 are very low. Clear increases in the overburdens of HF and HNO3 were observed during the course of September in the vortex core. HCl and NO2 exhibited smaller, less significant increases. The overburdens of the tropospheric source gases, N2O, CH4, CF2Cl2, and H2O were observed to much smaller over Antarctica than at mid-latitudes. This, together with the fact that HF over Antarctica was more that double its mid-latitude value, suggests that downwelling has occurred.
Toon, Goeff C.↗
An FTIR spectrometer for remote measurements of atmospheric composition
The JPL IV interferometer, and infrared Michelson interferometer, was built specifically for recording high resolution solar absorption spectra from remote ground-based sites, aircraft and from stratospheric balloons. The instrument is double-passed, with one fixed and one moving corner reflector, allowing up to 200-cm of optical path difference (corresponding to an unapodised spectral resolution of 0.003/cm). The carriage which holds the moving reflector is driven by a flexible nut riding on a lead screw. This arrangement, together with the double-passed optical scheme, makes the instrument resistant to the effects of mechanical distortion and shock. The spectral range of the instrument is covered by two liquid nitrogen-cooled detectors: an InSb photodiode is used for the shorter wavelengths (1.85 to 5.5 microns, 1,800 to 5,500/cm) and a HgCdTe photoconductor for the range (5.5 to 15 microns, 650 to 1,800/cm). For a single spectrum of 0.01/cm resolution, which requires a scan time of 105 seconds, the signal/noise ratio is typically 800:1 over the entire wavelength range.
Farmer, C. B.↗