Precipitation identifiers for meteorological features combining global GPM-IMERG retrievals and ERA5 reanalysis

The data collection provides 0.25-deg., 6-hourly global feature-precipitation categories from 2001 to 2019. The data is generated by merging GPM-IMERG observational rainfall (V6 final version) and atmospheric features identified by multiple object-based algorithms. Classified precipitation identifiers include rainfall associated with atmospheric rivers (AR), frontal systems (FT), low-pressure systems (LPS), mesoscale convective systems (MCS), and their co-occurrences (overlapping areas of features at a given time). In addition to algorithm-identified features, precipitation contributed from deep convection, non-deep convection, stratiform, and drizzle are pixel-wise defined using thresholds of CPC MERGE-IR brightness temperature and GPM-IMERG rain rate. The dataset is supported by the Department of Energy and Environment (DOEE): DE-SC0023244.

Methods
The categorization of global precipitation relies on recognizing four primary atmospheric features: atmospheric rivers (ARs), fronts (FTs), mesoscale convective systems (MCSs), and low-pressure systems (LPSs). Initially, identified atmospheric features with varying temporal and spatial resolutions are harmonized into a unified framework (6-hourly and 0.25-degree). GPM-IMERG precipitation data (0.1-degree resolution) is then coarse-grained to 0.25-degree for labeling using merged feature outputs. Additionally, precipitation attributed to deep convection, non-deep convection, stratiform, and drizzle is discerned at the pixel level using MERGE-IR brightness temperature data alongside GPM-IMERG precipitation. These classifications exclusively apply to rainy pixels not aligned with the four primary features. Rainy pixels within a specific feature boundary are considered associated with that feature object. For frontal systems represented as line segments, the line-segment masks are expanded outward by 250 km to generate two-dimensional bounded features. The identification of precipitation sources is conducted independently every 6 hours over 19 years (2001-2019). Detailed methodologies and demonstrations are accessible at https://docs.google.com/document/d/1O8NQesgyjIXv2X37wLsZ1EhgBdRKtvtPR7OYNBSBdBs/edit