1283 / 2024-09-20 22:45:41

Sketching the spatial disparities in heatwave trends by changing atmospheric teleconnections in the Northern Hemisphere

heatwave

Session 4 - Extreme Weather and Climate Events: Observations and Modeling

Pronounced spatial disparities in heatwave trends are bound up with a diversity of atmospheric signals with complex variations, including different phases and wavenumbers. However, assessing their relationships quantitatively remains a challenging problem. Here, using a network-searching approach to identify the strengths of heatwave-related atmospheric teleconnections (AT) with ERA5 reanalysis data, we quantify the close links between heatwave intensity and AT in the Northern Hemisphere. This way, approximately half of the interannual variability of heatwaves are explained and nearly 80% of the zonally asymmetric trend signs (attenuation vs. enhancement) are estimated correctly by the AT changes in the mid-latitudes. We also uncover that the likelihood of extremely hot summers has increased sharply by a factor of 4.5 after 2000 over areas with enhanced AT, but remained almost unchanged over the areas with attenuated AT. Furthermore, reproducing eastern European heatwave trends among various models of the Coupled Model Intercomparison Project Phase 6 largely depends on the simulated Eurasian AT changes, highlighting the potential significant impact of AT shifts on the simulation and projection of heatwaves.