EGU24-6500, updated on 08 Mar 2024
https://doi.org/10.5194/egusphere-egu24-6500
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Biases in stratosphere-troposphere coupling processes in S2S forecast systems

Amy Butler1, Chaim Garfinkel2, and Zachary Lawrence
Amy Butler et al.
  • 1National Oceanic and Atmospheric Administration, Chemical Sciences Laboratory, United States of America (amy.butler@noaa.gov)
  • 2The Fredy & Nadine Herrmann Institute of Earth Sciences, The Hebrew University Edmond J. Safra Campus, Jerusalem, Israel

Two-way coupling between the stratosphere and troposphere is recognized as an important source of subseasonal-to-seasonal (S2S) predictability. Extratropical coupling between the stratosphere and the surface may modulate the tropospheric circulation in predictable ways and/or provide forecast windows of opportunity. S2S forecast models may struggle to represent such coupling processes; at longer lead times, drifts in a model’s circulation related to model configurations, biases, and parameterizations have the potential to feedback and affect stratosphere-troposphere coupling. This presentation will highlight results from an international SPARC-SNAP (Stratospheric Network for the Assessment of Predictability) community effort to diagnose and characterize biases in stratosphere-troposphere coupling in S2S models. We find that in the Northern Hemisphere, the S2S forecast systems struggle to reproduce the strength of observed upward coupling from the troposphere to the stratosphere, while downward coupling is mostly well represented. In the Southern Hemisphere, forecast systems generally overestimate downward coupling strength, despite underestimating radiative persistence in the lower stratosphere.

How to cite: Butler, A., Garfinkel, C., and Lawrence, Z.: Biases in stratosphere-troposphere coupling processes in S2S forecast systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6500, https://doi.org/10.5194/egusphere-egu24-6500, 2024.

Supplementary materials

Supplementary material file

Comments on the supplementary material

AC: Author Comment | CC: Community Comment | Report abuse

supplementary materials version 1 – uploaded on 14 Apr 2024, no comments