Atmospheric synoptic circulations linked to short-term droughts over
Europe: A CMIP6 evaluation
Abstract
Synoptic circulation classifications represent a helpful tool to
characterize daily atmospheric patterns that strongly relate to the
dominant regional meteorological conditions. As global warming
influences the dynamical response of circulation patterns, their changes
might enhance or mitigate the behaviour of extreme weather events. We
investigate the synoptic circulations linked to short-term
meteorological droughts. The automated Jenkinson-Collison classification
is used to classify daily atmospheric patterns, based on mean sea-level
pressure data. Links between monthly relative frequency anomalies of the
synoptic circulations and short-term meteorological droughts were found
using the 1-month Standardized Precipitation Index (SPI-1). We evaluate
the ability of the historical runs of global climate models (GCMs) to
reproduce the observed features in the ERA5 reanalysis during the 1961 -
1990 climatological reference period. The evaluation is performed by a
multi model ensemble (MME) approach based on 22 GCMs. Links between the
mean directional flow characteristics of the circulation types and dry
months were found and are well represented in the GCMs MME. The
strongest relationships were found within anticyclonic, easterly and low
flow types since these circulation types show higher than normal
occurrences during dry events. Inverse relationships emerged from the
dominant westerly directional types given their lower occurrences
dominated by the dry months.