TY  - JOUR
A1  - Jaiser, Ralf
A1  - Akperov, Mirseid
A1  - Timazhev, A.
A1  - Romanowsky, Erik
A1  - Handorf, Dörthe
A1  - Mokhov, I. I.
T1  - Linkages between arctic and mid-latitude weather and climate
BT  - unraveling the impact of changing sea ice and sea surface temperatures during Winter
JF  - Meteorologische Zeitschrift
N2  - The study addresses the question, if observed changes in terms of Arctic-midlatitude linkages during winter are driven by Arctic Sea ice decline alone or if the increase of global sea surface temperatures plays an additional role. We compare atmosphere-only model experiments with ECHAM6 to ERA-Interim Reanalysis data. The model sensitivity experiment is implemented as a set of four combinations of sea ice and sea surface temperature boundary conditions. Atmospheric circulation regimes are determined and evaluated in terms of their cyclone and blocking characteristics and changes in frequency during winter. As a prerequisite, ECHAM6 reproduces general features of circulation regimes very well. Tropospheric changes induced by the change of boundary conditions are revealed and further impacts on the large-scale circulation up into the stratosphere are investigated. In early winter, the observed increase of atmospheric blocking in the region between Scandinavia and the Urals are primarily related to the changes in sea surface temperatures. During late winter, we f nd a weakened polar stratospheric vortex in the reanalysis that further impacts the troposphere. In the model sensitivity study a climatologically weakened polar vortex occurs only if sea ice is reduced and sea surface temperatures are increased together. This response is delayed compared to the reanalysis. The tropospheric response during late winter is inconclusive in the model, which is potentially related to the weak and delayed response in the stratosphere. The model experiments do not reproduce the connection between early and late winter as interpreted from the reanalysis. Potentially explaining this mismatch, we identify a discrepancy of ECHAM6 to reproduce the weakening of the stratospheric polar vortex through blocking induced upward propagation of planetary waves.
KW  - Weather regimes
KW  - Blocking
KW  - Cyclones
KW  - Wave Propagation
KW  - Stratosphere
Y1  - 2023
U6  - https://doi.org/10.1127/metz/2023/1154
SN  - 0941-2948
SN  - 1610-1227
VL  - 32
IS  - 3
SP  - 173
EP  - 194
PB  - Schweizerbart
CY  - Stuttgart
ER  - 
TY  - JOUR
A1  - Romanowsky, Erik
A1  - Handorf, Dörthe
A1  - Jaiser, Ralf
A1  - Wohltmann, Ingo
A1  - Dorn, Wolfgang
A1  - Ukita, Jinro
A1  - Cohen, Judah
A1  - Dethloff, Klaus
A1  - Rex, Markus
T1  - The role of stratospheric ozone for Arctic-midlatitude linkages
JF  - Scientific reports
N2  - Arctic warming was more pronounced than warming in midlatitudes in the last decades making this region a hotspot of climate change. Associated with this, a rapid decline of sea-ice extent and a decrease of its thickness has been observed. Sea-ice retreat allows for an increased transport of heat and momentum from the ocean up to the tropo- and stratosphere by enhanced upward propagation of planetary-scale atmospheric waves. In the upper atmosphere, these waves deposit the momentum transported, disturbing the stratospheric polar vortex, which can lead to a breakdown of this circulation with the potential to also significantly impact the troposphere in mid- to late-winter and early spring. Therefore, an accurate representation of stratospheric processes in climate models is necessary to improve the understanding of the impact of retreating sea ice on the atmospheric circulation. By modeling the atmospheric response to a prescribed decline in Arctic sea ice, we show that including interactive stratospheric ozone chemistry in atmospheric model calculations leads to an improvement in tropo-stratospheric interactions compared to simulations without interactive chemistry. This suggests that stratospheric ozone chemistry is important for the understanding of sea ice related impacts on atmospheric dynamics.
Y1  - 2019
U6  - https://doi.org/10.1038/s41598-019-43823-1
SN  - 2045-2322
VL  - 9
PB  - Nature Publ. Group
CY  - London
ER  -