MIARAD Dataset

• Source: Radar reflectivity data from the HydroMeteorological Service of Arpae (Emilia-Romagna, Italy).
• Geographical Coverage: Emilia-Romagna region, including flat Po Valley, the Apennines, and coastal areas.
• Time Period: 6 years (2015–2020).
• Data Resolution:
• Temporal: Scans taken every 5 minutes.
• Spatial: 1 km grid resolution.
• Area covered: 125 km radius per scan, covering a total of 71,172 square km.
• Reflectivity Range: 0 to 60 dBZ, clipped from an original range of -20 dBZ to 60 dBZ.
• Total Time Steps: 630,720 time steps in total.
• Precipitating Events: 179,264 time steps representing precipitating sequences.
• Non-precipitating Data: 71.5% of the data was discarded (non-precipitating).
• Dataset Split: -Training: 149,524 time steps. -Validation: 7,869 time steps.
• Test Sets: -Tokenizer Test Set (TTS): 21,871 radar images, focusing on extreme events. -Forecaster Test Set (FTS): 1,450 time steps from 10 selected extreme weather events (12 hours each).
• Data Augmentation: Random cropping, 90-degree rotations, and flipping applied during training.
• Reflectivity to Rainfall Conversion: Standard Marshall-Palmer Z-R relationship used for rain-rate estimation (mm/h).

This dataset supports the development and evaluation of the GPTCast model for radar-based precipitation nowcasting.