Origin of low-tropospheric potential vorticity in Mediterranean cyclones

Abstract. Mediterranean cyclones are extratropical cyclones, typically of smaller size and weaker intensity than other that develop over the main open ocean storm tracks. Nevertheless, can attain high intensities, even comparable to ones tropical thus cause large socioeconomic impacts in densely populated coasts region. After cyclogenesis takes place, a variety processes involved cyclone’s development, contributing with positive negative potential vorticity (PV) changes lower-tropospheric PV anomalies cyclone center. Although diabatic produce these known, it is still an question whether they occur locally within itself or remotely environment (e.g., near orography) subsequent transport high-PV air into This study introduces Lagrangian method determine origin anomaly, which applied climatologically ERA5 reanalysis 12 monthly simulations, performed integrated forecasting system (IFS) model. We define quantify so-called “cyclonic” “environmental” find part anomaly (60 %) produced cyclone, shortly prior (−12 h) cyclones' mature stage. 19.5 % environmental production mountains surrounding Basin plays significant role forming low-tropospheric therefore determining cyclones. The analysis tendencies from IFS simulations reveals major inside due convection microphysics, whereas turbulent momentum most environment.