Remote measurements of vertical profiles of atmospheric constituents with a UV-visible ranging spectrometer.

A study of the feasibility of retrieving vertical profiles of atmospheric constituents with a new UV-visible ranging spectrometer recently described by R. L. Jones [Optical Methods in Atmospheric Chemistry, U. Platt and H. I. Schiff, eds., Proc. Soc. Photo-Opt. Instrum. Eng. 1715, 393 (1992)] is presented. This instrument resembles a lidar, in that pulses of UV-visible radiation are transmitted vertically upward and backscattered to receiving optics. However, the pulse is a broadband source, and the receiving optics includes a two-dimensional CCD array that allows a series of absorption spectra to be recorded, each corresponding to a different altitude. This allows the simultaneous measurement of the vertical profiles of such atmospheric constituents as O(3), H(2)O, and NO(2) in the troposphere and lower stratosphere. Formal retrieval theory has been used to model the retrieval of vertical profiles with this instrument, demonstrating that it should be possible to obtain profiles at accuracies better than 30% and resolution better than 3 km up to altitudes of 12-15 km. The way in which the measurement error, flash-lamp pulse length, CCD recording interval, and mixing-ratio profile each affect the accuracy and the vertical resolution of the retrieved profile has also been investigated.