Water vapour and climate

Water vapour plays an ambiguous role in the climate system. On the one hand it is an important greenhouse gas in itself. On the other hand, its concentrations depend on temperature. Thus, the analysis of water vapour trends and their relation to temperature are an extremely relevant research field. To that end, Leonie Bernet and colleagues have analyzed atmospheric water vapour trends as measured by different measurement systems over Switzerland. A trend analysis tool developed at IMK was used for this purpose. The figure shows the temporal development of monthly mean water vapour content (top panel), anomalies (middle panel), and relative differences with respect to the TROWARA microwave radiometer in Berne (lower panel).

A particular problem were jumps in the GNSS data set. The IMK trend analysis tool has been designed to cope with such jumps. A positive water vapour trend of 2-5% per decade was found, and the expected temperature
dependence was observed. A good consistency between the data sets has been found.

For more information see: https://doi.org/10.5194/acp-20-11223-2020