Building a Climatology of Extratropical Cyclones and Fronts and Their Associated Precipitation

In the mid-latitudes, extratropical cyclones and their associated fronts play an integral role in both annual total and extreme precipitation. This work develops and tests a new methodology to investigate the contribution to global extreme precipitation from extratropical cyclone systems as a whole, as well as to isolate the individual contributions from the center of the cyclone and from the fronts associated with the low pressure system. Using TempestExtremes, a frontal diagnostic—which incorporates both thermal and dynamical variables—is calculated from the most up-to-date European Centre for Medium-Range Weather Forecasts reanalysis (ERA5) data to identify candidate frontal regions. These candidate fronts are then tracked in time and co-located with areas of extreme precipitation from NASA's Integrated Multi-satellite Retrievals for Global Precipitation Measurement (IMERG) data. Extratropical cyclones are similarly tracked in time and co-located with extreme precipitation using existing TempestExtremes capabilities. The frontal diagnostic is compared against other popular frontal detection parameters using various methodologies (e.g., techniques that only consider thermal variables). Relative precipitation contributions for fronts and extratropical cyclones are compared against existing estimates.