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Water vapour trends from GOME and SCIAMACHY satellite measurements

Sebastian Mieruch(1), Stefan Noel(1), Heinrich Bovensmann(1) and John P. Burrows(1)

(1) University of Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany


Global water vapour total column amounts have been retrieved from spectral data provided by the GOME (flying on ERS-2 since April 1995) and SCIAMACHY (onboard ENVISAT since March 2002) instruments. For this purpose the Air Mass Corrected Differential Optical Absorption Spectroscopy (AMC-DOAS) approach is used. The combination of the data from both instruments, which requires special treatment at the interchange, provides us with a long-term global dataset spanning already now more than 13 years with the possibility of extension up to 2020 by GOME-2 on Metop. Thus this dataset is well suited for a trend analysis.

Using linear and nonlinear methods from time series analysis as well as standard statistics the trends of water vapour contents (1996-2008) and their errors are calculated. Several factors affecting the trend such as the length of the time series, the magnitude of the variability of the noise and the autocorrelation of the noise are investigated. Special emphasize lies on the calculation of the significance of the observed trends which reveal local significant changes (decrease as well as increase) of water vapour concentrations in e.g.~Greenland, Eastern Europe and Saudi Arabia.

Additionally to the local trends, changes have been observed on a global scale. In the context of the increasing global mean temperature an increase in the globally averaged water vapour columns has been detected.