EGU24-18316, updated on 11 Mar 2024
https://doi.org/10.5194/egusphere-egu24-18316
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Investigating the Influence of Atmospheric Blocking Morphology on Predictability

Anupama K Xavier1,2, Oisín Hamilton1,2, Davide Faranda3,4,5, and Stéphane Vannitsem1
Anupama K Xavier et al.
  • 1Royal Meteorological Institute, meteo et climato dynamique, Uccle, Belgium (xavier.anupamak@meteo.be)
  • 2Université catholique de Louvain, Pl. de l'Université 1, 1348 Ottignies-Louvain-la-Neuve
  • 3Laboratoire des Sciences du Climat et de l’Environnement, UMR 8212 CEA-CNRS-UVSQ, Université Paris-Saclay, IPSL,91191 Gif-sur-Yvette, France
  • 4London Mathematical Laboratory, 8 Margravine Gardens London, W6 8RH, UK
  • 5Laboratoire de Météorologie Dynamique/IPSL, École Normale Supérieure, PSL Research University, Sorbonne Université,École Polytechnique, IP Paris, CNRS, Paris, 75005, France

Low-frequency variability (LFV) encompasses atmospheric and climate processes on time scales from a few weeks to decades.​ This includes atmospheric blockings, heat waves, cold spells, and at longer time scales long-term oscillations like the MJO, the NAO, ENSO….. Better understanding of LFV, could contribute to improved long term forecasts​. 

In the results described in Xavier et al, 2023, who used a reduced order atmosphere-land model (Demaeyer et al, 2020), weather patterns that involve atmospheric blocking to the west of a given topographical feature tend to have reduced predictability and show instability when contrasted with blocking occurrences situated to the east of such topographical elements. This finding aligns with actual meteorological occurrences, such as the persistence of North Pacific blocking patterns (Breeden et al., 2020; Kim and Kim, 2019). The shape and characteristics of the identified blocking events closely resemble North Pacific blocks, where a high-pressure system exists either on the western or eastern side of the underlying topography. In the physical world, these positions correspond to Asian and American continents on either side of the Pacific. Despite quasi-geostrophic models being overly simplified, using such reduced order models in this study allowed us to undertake such mathematical analysis. Thus allowing for a comparison with the real world…

In the current study, we aim to analyze these predictability differences based on the morphology of the blocking situations in the real-world scenario using the CMIP6 dataset. Blocking situations are identified using two different indices, the anomaly-based blocking index proposed by Sausen et al., 1995 and the local reversal of the meridional flow-based index proposed by Davini et al., 2012. Predictability is quantified using local dimension metrics and analogue studies in the identified blocking events. The findings are discussed from the perspective of the current literature on the predictability of blocking.

References

Xavier, A. K., Demaeyer, J., and Vannitsem, S.: Variability and Predictability of a reduced-order land-atmosphere coupled model, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2023-2257, 2023.

Demaeyer, Jonathan & De Cruz, Lesley & Vannitsem, S.: qgs: A flexible Python framework of reduced-order multiscale climate models. Journal of Open Source Software. 5. 2597. 10.21105/joss.02597, 2020.

Breeden, M. L., Hoover, B. T., Newman, M., and Vimont, D. J.: Optimal North Pacific blocking precursors and their deterministic subseasonal evolution during boreal winter, Monthly Weather Review, 148, 739–761, 2020

Kim, S.-H. and Kim, B.-M.: In search of winter blocking in the western North Pacific Ocean, Geophysical Research Letters, 46, 9271–9280, 2019.

Sausen, R., König, W., & Sielmann, F. (1995). Analysis of blocking events from observations and ECHAM model simulations. Tellus A, 47(4), 421–438.

Davini, P., Cagnazzo, C., Gualdi, S., & Navarra, A. (2012). Bidimensional diagnostics, variability, and trends of Northern Hemisphere blocking. Journal of Climate, 25(19), 6496–6509.

How to cite: K Xavier, A., Hamilton, O., Faranda, D., and Vannitsem, S.: Investigating the Influence of Atmospheric Blocking Morphology on Predictability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18316, https://doi.org/10.5194/egusphere-egu24-18316, 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 17 Apr 2024, no comments