On the relationship between atmospheric circulation patterns, recharge and soil moisture dynamics in Switzerland

• Identification of circulation patterns promoting dry conditions is possible.
• Spatial differences can be explained with topography-induced phenomena.
• No direct information about droughts from analyzing CP frequency changes.

SummaryThe aim of this paper is to test to what extent circulation patterns (CP) provide insights about groundwater recharge and soil moisture conditions in Switzerland. This is of special interest as climate change impact studies often suffer from the poor performance of climate models in representing precipitation behavior. CP-based downscaling procedures are very promising in increasing the reliability of such future precipitation projections. However, before applying such approaches to groundwater studies, the association between CP and groundwater dynamics has to be evaluated. Therefore, a Pearson χ2 test is applied to data from 14 locations in Switzerland to assess the significance of this association and to identify CP promoting dry conditions. To evaluate whether and to what extent future risks can be directly estimated from CP, it is analyzed how the relationships and frequencies are changing with time. It was possible to identify circulation patterns promoting dry conditions and spatial differences among Swiss regions, which could be explained with topography-induced phenomena. Not surprisingly, central high pressure systems seem to be related to conditions which promote low recharge and low soil moisture. However, due to large uncertainties in the CP-precipitation relationship and its classification, no information about recharge and soil moisture changes can directly be derived from changes in CP frequencies.