Grams, C. M.

Hauser, S.

Knippertz, P.

Riemer, M.

Teubler, F.

English

KITopen

EGU21-12847https://doi.org/10.5194/egusphere-egu21-12847EGU General Assembly 2021© Author(s) 2022. This work is distributed underthe Creative Commons Attribution 4.0 License.Potential vorticity dynamics of life cycles of blocked weatherregimes in the Euro-Atlantic region: A diagnostic frameworkSeraphine Hauser1, Christian M. Grams1, Michael Riemer2, Peter Knippertz1, and FranziskaTeubler21Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research, Department Troposphere Research,Eggenstein-Leopoldshafen, Germany (seraphine.hauser@kit.edu)2Institute for Atmospheric Physics, Johannes Gutenberg-University Mainz, Mainz, GermanyQuasi-stationary, persistent, and recurrent states of the large-scale extratropical circulation, so-called weather regimes, characterize the atmospheric variability on sub-seasonal timescales ofseveral days to a few weeks. Weather regimes featuring a blocking anticyclone are of particularinterest due to their long lifetime and potential for high-impact weather. However, state-of-the-artnumerical weather prediction and climate models struggle to correctly represent blocking lifecycles, which results in large forecast errors at the medium-range to sub-seasonal timescale.Despite progress in recent years, we are still lacking a process-based conceptual understanding ofblocked regime dynamics, which hinders a better representation of blocks in numerical models. Inparticular the relative contributions of dry and moist processes in the onset and maintenance of ablock remain unclear.Here we aim to revisit the dynamics of blocking in the Euro-Atlantic region. To this end weinvestigate the life cycles of blocked weather regimes from a potential vorticity (PV) perspective inERA5 reanalysis data (from 1979 to present) from the European Centre for Medium-RangeWeather Forecasts. We develop a diagnostic PV framework that allows the tracking of negative PVanomalies associated with blocked weather regimes. Complemented by piecewise PV-tendencies -separated into advective and diabatic PV tendencies - we are able to disentangle different physicalprocesses affecting the amplitude evolution of negative PV anomalies associated with blockedregimes. Most importantly, this approach newly enables us to distinguish between the roles of dryand moist dynamics in the initiation and maintenance of blocked weather regimes in a commonframework. A first application demonstrates the functionality of the developed PV framework andcorroborates the importance of moist-diabatic processes in the initiation and maintenance of ablock in a regime life cycle. Powered by TCPDF (www.tcpdf.org)

Potential vorticity dynamics of life cycles of blocked weather regimes in the Euro-Atlantic region: A diagnostic framework

https://publikationen.bibliothek.kit.edu/1000142018/141036727

Potential vorticity dynamics of life cycles of blocked weather regimes in the Euro-Atlantic region: A diagnostic framework

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