Validation of the ORA spatial inversion algorithm with respect to the Stratospheric Aerosol and Gas Experiment II data.

We present the results of a comparison of the total extinction altitude profiles measured at the same time and at same location by the ORA (Occultation Radiometer) and Stratospheric Aerosol and Gas Experiment II solar occultation experiments at three different wavelengths. A series of 25 events for which the grazing points of both experiments lie within a 2 degrees window has been analyzed. The mean relative differences observed over the altitude range 15-45 km are -8.

Radiometer for the measurement of water vapor in the upper atmosphere from space.

We describe the design, the development, and the calibration of a radiometer to measure water vapor abundance in the middle atmosphere, using the solar occultation technique from an orbiting platform. The use of gas cells containing water vapor and carbon dioxide leads to a relatively simple, but sensitive, design. This radiometer is shown to be capable of detecting water vapor in the mesosphere, where, because of dissociation by the Sun, the amounts are very small, of the order of 1 part per 10(6) or less.

Liquid helium cryopump and reliable opening device for a balloon-borne mass spectrometer.

The design, technical characteristics, and test and flight results of a liquid helium cryopump and an opening device operating on board a balloon-borne mass spectrometer combining a cryopump and a quadrupole mass filter are reported. The gas inlet of this mass spectrometer is opened through a simple and reliable remote-controlled system, which is also described.