First global data set on mean age of stratospheric air and its temporal variations derived from MIPAS
MIPAS SF6 was zonally binned into 10 deg latitude bins and transformed in age of air on basis of in situ ground-based observations by NOAA/ESRL. The age of air time series for all latitude/altitude bins were fitted by a simple parametric approach including a constant, a linear, and various sine and cosine terms for seasonal, semi-annual and further oscillations. A QBO proxy was also fitted to the time series. The linear terms of the fits are presented for their altitude/latitude bins in the figure.