EGU22-7072
https://doi.org/10.5194/egusphere-egu22-7072
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Atmospheric Rossby Waves as a Link Between North Atlantic Storm Track Variability and Eastern Mediterranean Cyclones

Dor Sandler1, Baruch Ziv2, Hadas Saaroni1, Dorita Rostkier-Edelstein3,4, and Nili Harnik1
Dor Sandler et al.
  • 1Porter School of the Environment and Earth Sciences, Tel Aviv University, Tel Aviv, Israel (dor.sandler@gmail.com)
  • 2Department of Life and Natural Sciences, The Open University of Israel, Israel
  • 3The Fredy and Nadine Herrmann Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
  • 4Department of Environmental Physics, Environmental Sciences Division, IIBR, Ness-Ziona, Israel

The Mediterranean Basin has several features that enhance cyclonic activity, such as its complex topography and sharp land-sea temperature differences. However, some processes occurring outside the basin can influence its seasonal variability. In this work, we highlight the relationship between the North Atlantic Storm Track (NAST) and cyclones passing through the Eastern Mediterranean (EM). We use Empirical Orthogonal Function (EOF) analysis of upper-level meridional wind variance to inspect monthly NAST regimes and their influence on wintertime flow in the EM.

We find that the higher functions (EOF4-5) show stronger links to the region and specifically, to anomalies in synoptic fields associated with cyclones (upper-level potential vorticity, sea level pressure) and in monthly precipitation. These functions manifest as a pair of orthogonal zonal waves, reminiscent of subseasonal teleconnections that were previously linked to seasonal precipitation extremes in the EM (the South Levant pattern). It is hypothesized that this connection is mainly brought about by large-scale adiabatic advection of PV in the upper levels. Meanwhile, the two leading NAST modes (“pulsing” and latitudinal “shifting”) were found to produce a comparatively smaller effect.

On the daily scale, we investigate the NAST-EM connection through the lens of zonally propagating Rossby wave packets, in both reanalysis and CMIP6 models (which capture the patterns well).

How to cite: Sandler, D., Ziv, B., Saaroni, H., Rostkier-Edelstein, D., and Harnik, N.: Atmospheric Rossby Waves as a Link Between North Atlantic Storm Track Variability and Eastern Mediterranean Cyclones, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7072, https://doi.org/10.5194/egusphere-egu22-7072, 2022.