Life-cycle analysis of fronts and their precipitation in high-resolution observations, reanalyses, and models
Extratropical cyclones and their associated fronts are the dominant synoptic-scale weather feature and contribute a large fraction of the total and extreme precipitation in the midlatitudes. This work uses an object feature-tracking method to explore the life cycle characteristics of frontal objects and precipitation in reanalysis and Earth system model datasets. Frontal objects are identified and tracked in ERA5 reanalysis data and NASA’s IMERG precipitation is associated with these objects. Feature-tracking statistics—like genesis, lysis, duration, intensity, and average and extreme precipitation—are calculated using these tracked frontal objects. Frontal trajectories are created, and cluster analysis is performed to form an archetypal set of fronts. Regional impacts, including precipitation, are investigated from these frontal archetypes. This work presents a unique and versatile methodology for tracking fronts in arbitrarily-gridded datasets that has the capacity to output novel feature-tracking statistics. These statistics can provide useful information on historical and future trends of fronts using observational and Earth system model data. To demonstrate how this methodology can be used for model evaluation, we compare climatologies of different approaches to high-resolution simulation in the Energy Exascale Earth System Model (E3SM). This includes two E3SM prototypes—a high resolution (HR), with a horizontal resolution of ~25 km, and a multi-scale modeling framework (MMF), which uses embedded cloud-resolving models. These model configurations have been shown to improve frequency and intensity biases for precipitation compared to conventional low resolution configurations. Applying the front and precipitation tracking methodologies to these simulations will inform which is best suited for exploring future changes in frontal precipitation.