Institute of Meteorology and Climate Research

SF6 observations from satellites, ground-based FTIR and surface in-situ stations agree with each other


In the lower panel, SF6 daily mean observations from in-situ measurements at the surface at the HATS site America Samoa (blue), monthly means of ground-based FTIR measurements at Reunion (Maïdo and St Denis) (red), monthly means of MIPAS observations at 11 km altitude averaged over 20-25o S (black), and monthly mean ACE-FTS observations at 12.5 km averaged over 0-40o S (brown) are compared. The error bars provide the sample standard deviation of the respective month. The ground-based FTIR SF6 volume mixing ratios are derived from the measured total column applying a constant a priori profile.

The upper panel of the figure shows the geographical area of monthly averaging for the satellite instruments MIPAS (black/grey) and ACE-FTS (brown) together with the locations of the stations in America Samoa (blue) and Reunion (red).

The comparison performed in this paper demonstrates that the observations from the four sources agree well with each other. Compared to the in situ measurements at the surface (blue). MIPAS data after 2004 seem to have a consistent slight high bias, while ACE-FTS data show a larger scatter around the reference data set. The FTIR data have some scatter, too, and have relatively large uncertainties. The growth rates of SF6 from all four observational data sets agree very well.

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