A Study of Extratropical Cyclones Statistics in Present-Day and Warmer Climates

Extratropical cyclone (ETCs) tracking algorithms play a crucial role in studying the behavior and potential changes of ETCs in a warming climate. As the global climate continues to evolve, understanding the genesis and development of these low-pressure systems becomes increasingly important. By employing tracking algorithms, we can analyze the trajectories and intensities of ETCs, providing valuable insights into how these weather phenomena may be affected by rising temperatures. This study utilizes the Geophysical Fluid Dynamics Laboratory (GFDL) Atmospheric Model version 4 (AM4) to simulate both the current and warmer climates, applying two distinct tracking algorithms—TempestExtremes and Hodges—to identify and analyze ETC candidates.

TempestExtremes identifies ETCs based on sea level pressure anomalies, while the Hodges tracker is based on maximum relative vorticity. The use of these two different methodologies offers a comprehensive approach to understanding ETC characteristics, but it also introduces uncertainty in the model statistics due to potential discrepancies between the tacking algorithms. These differences highlight the importance of understanding the biases inherent in each tracking method, as they can significantly influence the interpretation of the results.

Preliminary analysis suggests a systematic poleward shift in the density and intensity of ETC tracks under global warming when using both tracking algorithms, in line with previous studies. However, this shift could be influenced by specific model configuration like the constant sea ice concentration in AM4, which may affect the accuracy of the tracking results. Further investigation is required to evaluate the robustness of the poleward shift of storm track, and to better understand the possible mechanisms of these ETC changes in a warming climate.