Title: Assessing Cyclones of Tropical Origin (CTO) risks in mid-latitudes: Huracán
Abstract: Huracán is a strategic collaboration between the UK and US with the overarching objective to deliver a new, physically based understanding of the risks posed to the British Isles/Western Europe (BIWE) and the Northeast United States (NEUS) by cyclones of tropical origin (CTOs) in a changing climate.
We have systematically explored a number of re-analysis and prediction products, covering a range of temporal scales, in order to assemble a database that can offer a robust understanding of the occurrence of CTO development and landfall, including a number of case studies. Developing criteria to distinguish CTOs, using an adapted form of phase space diagnostics, suitable for mid-latitudes, is enabling the construction of event sets, which in turn feed into methods to relate CTO to drivers.
Our preliminary results confirm previous findings in terms of the annual frequency of events on both sides of the Atlantic, but provide additional information on the characteristics of each storm during its lifetime. Some of the case studies that have been identified so far are candidates for official extension, e.g. in terms of the early and late stages of their lifetimes, but are certainly suitable for development into storylines. We have also assessed the latest generation of global climate models, at resolutions between 10 and 3km, in order to determine their suitability when used for projecting future CTO risks in mid latitudes. We find that the location of maximum intensity in the TC (warm core) phase starts to be reasonably realistic using mesh sizes of 10km, while a realistic representation of rapid intensification requires the finest available resolution.
