Temperature and composition measurements from the l.r.i.r. and l.i.m.s. experiments on Nimbus 6 and 7

Abstract

The limb radiance inversion radiometer (l.r.i.r.) on Nimbus 6 was the first orbiting infrared limb scanner. It had four channels with which to determine temperature, Oz and H aO in the stratosphere and low mesosphere. The limb infrared monitor of the stratosphere (l.i.m.s.) is a similar six-channel instrument launched on Nimbus 7 in October 1978 to measure temperature, O ₃ , H ₂ O , NO ₂ and HNO ₃ . The instrumentation and inversion techniques are briefly described. In this method, the outwelling radiance in the 15 pm bands of CO ₂ is inverted to yield temperatures as a function of pressure; the temperature is then used w ith the radiance emitted by a trace gas to determine its concentration. L.r.i.r. temperature and ozone results show high precision and good agreement with rocket measurements from the tropopause into the mesosphere. Preliminary l.i.m.s. results show that temperatures may be retrieved into the troposphere, and the capability to determine constituent concentrations in the part / 10 ⁹ range from a satellite for the first time. The application of such data for photochemical dynamical and transport problems is discussed.