Satellite-borne measurements of middle-atmosphere composition

Abstract
A number of satellite experiments have been launched in recent years with the goal of providing fundamental data needed for analysis of photochemistry, radiation, dynamics, and transport processes. Collectively, these experiments have accumulated information on the vertical and horizontal distributions of a host of minor constituents in the middle atmosphere. The combined satellite data set includes new global measurements of O 3 , NO 2 , N 2 O , HNO 3 , CH 4 , H 2 O, and aerosols, and more-limited data on CO, N 2 O 5 , CIONO 2 , HNO 4 , COF 2 , and CH 3 CI. These data have provided descriptions of (1) the geographic extent and year-to-year change in the recently discovered Antarctic ozone hole; (2) interannual variability in N 2 O and CH 4 ; (3) the winter high latitude NO 2 ‘cliff’; (4) exchange of NO 2 from the mesosphere to the stratosphere during polar night; (5) a lower limit total odd nitrogen distribution that displays a maximum that exceeds model calculated values; (6) variations in the newly discovered polar stratospheric clouds (PSCS) seen in the north and south polar regions; and (7) details of latitudinal and temporal aerosol variability. The existing satellite data set is deficient in certain key measurements including OH, HO2 , H 2 O 2 , polar night N 2 O 5 , radiatively important aerosol properties, and simultaneous measurements of aerosols and gases involved in heterogeneous processes.