How a warmer Mediterranean preconditions the upper-level environment for the development of Medicane Ianos

• DOI: 10.5194/egusphere-2023-2431
• Publication Date: 2023-11-02T09:31:51Z
• Authors: Claudio Sanchez; Suzanne Gray; Ambrogio Volonte; Florian Pantillon; Segolene Berthou; Silvio Davolio
• Keywords: Diabatic; Predictability; Positive vorticity advection

Abstract. Medicane Ianos in September 2020 was one of the strongest medicanes observed last 25 years. It was, like other medicanes, a very intense cyclone evolving from baroclinic mid-latitude low into tropical-like cyclone. The dynamical elements necessary to improve predictability are explored with use simulations Met Office Unified Model (MetUM) at 2.2 km grid spacing for five different initialisation times, four two days before Ianos's landfall. Simulations also performed Sea Surface Temperature (SST) uniformly increased and decreased by 2 K analysis explore impact enhanced reduced sea-surface surface fluxes on evolution. All +2 SST able simulate medicane Ianos, albeit too intensely. control initialised earliest times fail capture preceding precipitation events right locations, subsequent development Ianos. Amongst -2 SST, only latest time develops medicane. Links between upper-level processes investigated. We find (i) bubble low-valued potential vorticity (PV) formed within trough above where developed, diabatic associated event triggered balanced divergent flow upper-levels which contributed creation maintenance this low-PV bubble, as shown results semi-geostrophic inversion tool, (ii) Upper-level geostrophic advection forced quasi-geostrophic ascent during cyclogenesis, (iii) dominated deep convection vertical PV tower continued produce diabatically-induced outflow aloft, thus sustaining development. missing any these three do not develop Our imply that essential highlighting importance interactions near-surface small-scale flow. A warmer strengthens enables be predicted initiated earlier failed generate SSTs.