Classify rainfall intensity (light, moderate, heavy) from the hourly rate.
| Item | Formula / Note | Source / Standard |
|---|---|---|
| Rain intensity | I = h/t | Observation specs |
| 24h classes | 10/25/50/100/250 mm thresholds | GB/T 28592-2012 |
| Shorter windows | Separate 12h/1h thresholds | GB/T 28592-2012 |
| Return period | i = A(1+C·lgP)/(t+b)^n | GB 50014-2021 |
| Short-duration | ≥20 mm/h heavy short burst | QX/T 116 |
| Radar retrieval | Z = 200R^1.6 | M&P 1948 |