Andre Girard

Simultaneous measurements of No and No2 in the stratosphere

Abstract Simultaneous measurements of NO and NO 2 in the stratosphere leading to an NO x determination have been performed by means of i.r. absorption spectrometry using the Sun as a source in the 5·2 μm band of NO and in the 6·2 μm band of NO 2 . The observed abundance of NO P peaks at 26 km where it is equal to (4·2 ± 1) × 10 9 cm −3 . The volume mixing ratio of NO p was observed to vary from 1·3 × 10 −9 at 20 km to 1·3 × 10 −8 at 34 km.

Vertical Distribution of NO, NO 2 , and HNO 3 as Derived from Stratospheric Absorption Infrared Spectra

This paper is devoted to the results concerning NO, NO(2), and HNO(3) obtained during airborne experiments performed in June-July 1973 on Concorde 001. The altitude of flight was about 16 km. Results concerning NO are, within the accuracy of measurement, in agreement with results of a previousspectrometric balloonborne experiment conducted jointly by IASB and ONERA (14 May 1973). Nitric oxide is concentrated in stratospheric layers clearly above the flight altitude. Integrated amount of NO along the optical path is (4 +/- 1.5) x 10(16) mol cm(-2) for a solar elevation varying from +2 degrees above the horizontal plane to -1 degrees . A value of 6 x 10(8) mol cm(-3) may be given as an upper limit for the local concentration at the flight altitude. Thereis no significant difference in the integrated amount observed at sunset and sunrise. Measured value of NO(2) local concentration at 15.5 km is (1.1 +/- 0.2) x 10(9) mol cm(-3), in sunset conditions. This value is not greatly modified between 15 km and 30 km. Measured value of HNO(3). This value increases with altitude between 15 km and 20 km. The local concentration is maximum at 20 km. The measured value is (2 +/- 1) x 10(10) mol cm(-3) at 20 km. It seems that local concentration decreases rapidly above 20 km.

Global results of grille spectrometer experiment on board Spacelab 1

Measurements of atmospheric trace gases have been performed during the first Spacelab mission, on board the Space Shuttle, from 28 November to 8 December 1983. The principle of the observations is absorption spectroscopy, in the infrared, using the sun as a light source during sunset or sunrise periods. The instrumental set-up and the flight operations, already described in previous papers, are briefly summarized. The automatic retrieving method for the processing of the spectra is explained. Finally, all the results, in terms of vertical concentration profiles, are given for NO, NO2, CH4, N2O, CO, CO2 and H2O. Several results have been published (Laurent et al., 1985, Nature315, 126; Muller et al., 1985a, J. Optics (Paris) 16, 155 ; 1985b, Geophys. Res. Lett.12, 667 ; Vercheval el al., 1986, Ann. Geophys.4A, 161 ; Laurent et al., 1986, Planet. Space Sci.34, 1067). This last version may be slightly different, due to recently available and more accurate orbital parameters.

Correlated seasonal and climatic variations of trace constituents in the stratosphere

SummarySpectrometric experiments performed, in November 1976, within the framework of the ‘Latitude Survey Mission’ on board the NASA Convair 990 from Ames Research Center are briefly deseribed. The results presented concern odd nitrogen molecules, HCl and water vapor. In terms of vertical column density, HNO3 is predominant over NO+NO2 at all latitudes higher than 40 degrees. A seasonal variation of NO2 abundance is observed, with larger values in the summer hemisphere at high latitude. The mean zenith column density of HCl above 11 km is 1.5×1015 mol.cm−2, with no evidence for any seasonal or climatic variation. Local number densities as high as 1.4×1010 mol.cm−3 for HNO3 and 5.4×1014 mol.cm−3 for water vapor have been measured during the same flight near 11 km.

Atmospheric Physics and Earth Observations Sample Performance of the Grille Spectrometer

The grille spectrometer observed the setting and rising sun 18 times during the Spacelab 1 mission. In addition to solar absorption lines, many of which had not been observed before, atmospheric spectral absorptions due to carbon monoxide and carbon dioxide were observed at heights tangent to the thermosphere (greater than 85 kilometers), and absorptions due to ozone, water, methane, and nitrous oxide were observed in the mesosphere (greater than 50 kilometers). The strongly coupled molecules NO-NO2 and HC1-HF were observed as pairs in the stratosphere. Methane is presented as an example of the instrumental operations because of the characteristic aspect of the Q branch of its v3 band.

Trace constituents measurements deduced from spectrometric observations on-board spacelab

Abstract The observation of infrared absorption lines by means of a grille spectrometer on board Spacelab 1 allows the determination of Co2 and CO in the low thermosphere and in the middle atmosphere. Equal abundances of CO and CO2 are found at 115 ± 5 km altitude. CO2 is observed to depart from its homospheric volume mixing ratio near 100 km, dropping by a factor of 10,15 km higher. The CO largest number density is observed near 70 km altitude, close to the H Lyman alpha photoproduction peak. The analysis of one run dedicated to the observation of water vapor shows a middle atmospheric mixing ratio of this species within the limits : 3 to 8 ppmv up to 70 km altitude, with the indication of an increase from 30 to 50 km altitude. The H2O mixing ratio drops very rapidly above 70 km. The comparison of the results from strong and weak H2O and CO2 lines shows the need to refine the line profile model.

Middle atmospheric water vapor observed by the Spacelab one grille spectrometer

Two water vapor atmospheric concentration profiles have been obtained, one at 33°N, 59°E and the other at 68°S, 124°W, during the Spacelab One flight respectively on 2 and 1 December 1983. These profiles extend from the middle stratosphere up to mesopause and show significant differences above the altitude of 70 km, the Antarctic profile showing then higher concentrations. This result correlates with Spacelab One carbon monoxide observations and SM E ozone results as far as the hydroxyl radical chemistry is concerned.

Profils experimentaux de l’horizon infrarouge de la terre

This paper presents experimental ir horizon profiles of the earth seen fromoutside the atmosphere. Measurements were made from a capsule which reached 175 km. The attitude was controlled during the whole flight by means of agyroscopic device. Seven spectral channels were studied, especially: ozone (9.6 micro), CO(2) (14-16 micro), the range of atmospheric window (11micro), and a broad channel (1-50 micro) that was the only one of the firstexperiment in 1965. The spatial limit of resolution is 0.16 degrees , and theattitude in space of the capsule has been reconstructed with an accuracy equalto 0.05 degrees due to a star mapper. Results are expressed as variations ofradiance with respect to tangential height for the different spectral channels.