Stratospheric methane distributions: comparisons of a CIRA reference model and recent observational data
The current CIRA reference model for stratospheric methane (Taylor et al., Handbook for MAP, Vol. 31) was constructed in the early 1980's using data produced by the Nimbus 7 Stratospheric and Mesospheric Sounder (SAMS). A large number of measurements have become available more recently, including those from instruments carried by the Upper Atmosphere Research Satellite (UARS), and future CIRA models are expected to benefit from the relatively high resolution of the UARS measurements, as well as from the greater spatial coverage possible. CIRA model methane fields are compared with measurements from the UARS ISAMS and CLAES instruments. The CIRA and UARS data are generally similar, but the UARS values are somewhat larger than those of the CIRA model. Possible improvements to future reference models are considered, including the need to quantify longitudinal, daily and interannual variability.