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Infrared absorption by O3, NO, NO2, N2O, HNO3, CO, COS, CH4 and H2O have been observed from a balloon platform at 40 km of altitude and 44°N latitude with a grille spectrometer. The resolution is, for the most part, better than 0.1 cm−1. An analysis is made of the causes of uncertainties. Height profiles are deduced for these species down to 20 km. The mixing ratios near 40 km are 8.5±1.5 ppm for ozone, 8. ±1 ppm for water vapor, and 19±5 ppb for carbon monoxide. Nitric acid and carbonyl sulfide exhibit a decreasing profile with altitude. Mixing ratios near 30 km are <10–10 for COS and 8±1 ppb for HNO3. Some common observations are made, related to the particular temperature profile, which emphasize the importance of simultaneous measurements of stratospheric species and meteorological parameters.

Solar infrared absorption spectra have been recorded from an aircraft during nine flights, in April–May 1980, at various latitudes between 62° north and 60° south. Using a solar occultation technique, the instrument is a spectrometer associated with a heliostat and designed for scanning automatically, in a repetitive sequency of measurements, a set of selected narrow spectral intervals within the spectral range 1000 to 4000 cm−1. Simultaneous measurements are presented concerning NO2, COS, H2O, CH4, N2O, O3, CO, HNO3, HF, and HCl. The results deduced from observations are the vertical column density above the flight altitude, near 11.5 km, the local concentration at the flight altitude, and qualitative information about the stratospheric vertical profile. A similar variation is observed for HNO3, HCl, and HF: for these three species, the vertical column density increases from the equator to the polar region in both hemispheres. The CO vertical column density decreases by a factor of 4 from the equator to high latitude in both hemispheres, with values slightly larger in the northern equatorial region than in the southern hemisphere at the same latitude. The latitudinal variation of H2O vertical column density is discussed in relation to the tropopause height. Some similarities are observed for latitudinal and seasonal variations of nitrogen dioxide and ozone.

The characterization of high clouds as performed from selected spaceborne observations is assessed in this article by employing a number of worldwide ground-based lidar multiyear datasets as reference. Among the latter, the ground lidar observations conducted at Lannion, Bretagne (48.78N, 3.58W), and Palaiseau, near Paris [the Site Instrumental de Recherche par Té lé dé tection Atmosphé rique (SIRTA) observatory: 48.78N, 2.28E], both in France, are discussed in detail. High-cloud altitude statistics at these two sites were found to be similar. Optical thicknesses disagree, and possible reasons were analyzed. Despite the variety of instruments, observation strategies, and methods of analysis employed by different lidar groups, high-cloud optical thicknesses from the Geoscience Laser Altimeter System (GLAS) on board the Ice, Cloud and land Elevation Satellite (ICESat) were found to be consistent on the latitude band 408-608N. Respective high-cloud altitudes agree within 1 km with respect to those from ground lidars at Lannion and Palaiseau; such a finding remains to be verified under other synoptic regimes. Mean altitudes of high clouds from Lannion and Palaiseau ground lidars were compared with altitudes of thin cirrus from the Television and Infrared Observation Satellite (TIROS) Operational Vertical Sounder (TOVS) Path-B 8-yr climatology for a common range of optical thicknesses (0.1-1.4). Over both sites, the annual altitude distribution of thin high clouds from TOVS Path-B is asymmetric, with a peak around 8-9.5 km, whereas the distribution of high clouds retrieved from ground lidars seems symmetric with a peak around 9.5-11.5 km. Additional efforts in standardizing ground lidar observation and processing methods, and in merging high-cloud statistics from complementary measuring platforms, are recommended.

Results obtained from two experiments concerning the repartition of carbon monoxide in the stratosphere are presented and compared to model predictions. Infrared solar absorption spectra were recorded during a balloon flight from Aire‐sur‐Adour, France (about 44°N Latitude), in September 1980. The height profile of the mixing ratio presents a minimum of 8±1 ppb around 22–25 km; it reaches 14±1 ppb at 35 km. A similar experiment was performed in April–May 1980 from an aircraft (Stratoz II mission) between 64°N and 62°S. The integrated vertical amount above 11.5 km is deduced. There is an important variation of this amount with a maximum (4.45×1017 mol cm−2) at low latitude and a minimum (0.90×1017 mol cm−2) at high latitude related to the height of the tropopause. An asymmetric distribution of CO in the two hemispheres can also be observed.

For a long time fluorescence techniques have provided interesting information in oceanography. Lidar (LIght Detection And Ranging) has been used to have fast profiling tools over several meters especially in high dynamic water masses. While fluosensors provide the fluorescence response to a well defined excitation in a small volume, remote sensing operates over several meters and their power to excite fluorescence at a range R depends on optical properties of the medium during the light propagation. In order to study the influence of the propagation properties of the aquatic medium on spectra from fluorescence Lidar a new ranging concept was realized. The presented study is focused on the bistatic design of Lidar combined with a spectral analysis of the backscattered signal for tomoscopic applications. The data were obtained with a frequency doubled Nd:YAG (A=532 nm) and a gated angular resolved detection. While the time base of the system can be compared to ranging by other on-axis Lidar, the spatial dimension of the signal brings complementary information of the light flux distribution as a function of the angle of incidence. The bistatic configuration of this Lidar permits geometrical ranging by a set of detection channels, detecting simultaneously the spectrum (532nm -720nm) with the same system time base. The analysis of fluorescence by the bistatic angular resolved detection is focussed on the temporal aspects of fluorescence in near field data of this Lidar. First sea trials with this Lidar have shown the potential for the investigation of fluorescence profiles even in very turbid estuaries.

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