Do Changing Weather Types Explain Observed Climatic Trends in the Rhine Basin? An Analysis of Within‐ and Between‐Type Changes

Abstract

For attributing hydrological changes to anthropogenic climate change, catchment models are driven by climate model output. A widespread approach to bridge the spatial gap between global climate and hydrological catchment models is to use a weather generator conditioned on weather patterns (WPs). This approach assumes that changes in local climate are characterized by between‐type changes of patterns. In this study we test this assumption by analyzing a previously developed WP classification for the Rhine basin, which is based on dynamic and thermodynamic variables. We quantify changes in pattern characteristics and associated climatic properties. The amount of between‐ and within‐type changes is investigated by comparing observed trends to trends resulting solely from WP occurrence. To overcome uncertainties in trend detection resulting from the selected time period, all possible periods in 1901–2010 with a minimum length of 31 years are analyzed. Increasing frequency is found for some patterns associated with high precipitation, although the trend sign highly depends on the considered period. Trends and interannual variations of WP frequencies are related to the long‐term variability of large‐scale circulation modes. Long‐term WP internal warming is evident for summer patterns and enhanced warming for spring/autumn patterns since the 1970s. Observed trends in temperature and partly in precipitation are mainly associated with frequency changes of specific WPs, but some amount of within‐type changes remains. The classification can be used for downscaling of past changes considering this limitation, but the inclusion of thermodynamic variables into the classification impedes the downscaling of future climate projections.

Atmospheric circulation modulates the spatial variability of temperature in the Atlantic–Arctic region

“…This method was recently used to quantify how observed trends of temperature or precipitation can be explained by changes in atmospheric circulation (Fleig et al , ). The method was successfully applied to Europe (Nilsen et al , ; Murawski et al , ) and central Asia (Gerlitz et al , ).…”

Hydraulic modelling approaches to decrease uncertainty in flood frequency relations

“…However, a basic question dealing with a long temporal ood series is whether the ood-producing mechanisms in the past have a similar consequence as those of the present. This problem of non-stationary comprises two factors, namely: climate change and land use change (Murawski et al, 2018). Both factors inuence the frequency, timing and peak value of ood events.…”

“…However, literature shows consensus that varying climate conditions during the considered time period inuence ood frequency relations (e.g. Khaliq et al (2006); Murawski et al (2018)).…”

Concurrent Hydroclimatic Hazards from Catchment to Global Scales

“…Previous studies have investigated linkages between weather patterns (or large-scale atmospheric circulation) and local extreme events, such as heavy rainfall, storms, floods and heatwaves (Conticello et al, 2018;De Luca et al, 2017;Farnham et al, 2018;Matthews et al, 2016b;Merz et al, 2014;Murawski et al, 2018Murawski et al, , 2016Pattison and Lane, 2012;Wilby et al, 2011). The conventional approach to flood analysis at the single catchment scale is being extended to frameworks with inter-related hazards, driven by global climate modes, covering multiple catchments (Merz et al, 2014).…”

“…Moreover, weather patterns extracted from AOGCMs have also been used to downscale local climate variables, such as temperature, precipitation, radiation and humidity at local scales (Murawski et al, 2016;Wilby and Wigley, 1997;Xu et al, 2007). However, AOGCMs vary in their ability to simulate the frequency, seasonality and persistence of weather patterns at regional scales (Murawski et al, 2016(Murawski et al, , 2018. Some studies have linked heavy precipitation events to atmospheric circulation states, such as the 850hPa geopotential height field or integrated vapour transport (IVT) (Conticello et al, 2018), and found connections between selected weather patterns and multi-basin flooding driven (Otero et al, 2018;Stryhal and Huth, 2018;Woollings et al, 2018).…”