Resources · Explainer
How do ground gauges differ from radar?
Summary
Radar estimates precipitation distribution over a wide area, while a rain gauge directly measures the rain that falls at its installation point. Using both together lets each cover the other’s gaps. For urban flood response, it helps to track a storm’s movement with radar and confirm the actual rainfall at places where water collects with field observation.
At a glance
| Aspect | Weather radar | Ground rain gauge (field observation) |
|---|---|---|
| Observation method | Estimates precipitation intensity from reflected radio signals | Directly measures the amount of rain entering the collector |
| Strength | Captures precipitation distribution and movement over a wide area | Point-level measured value, recorded at short time intervals |
| Weakness | Can differ from surface rainfall and needs correction | Gaps exist between observation points |
| Role in urban flood response | Confirms a storm’s approach and direction of movement | Confirms actual rainfall at places where water collects |
This table explains general observation principles. It does not compare the performance of any specific radar or product.
Why use both together
The precipitation distribution radar shows is useful for judging where a storm is heading. But what actually determines whether flooding occurs in a city is the amount of rain that fell at a specific place.
Dense ground observations serve as a baseline to check and calibrate radar estimates, and in turn radar fills the space between observation points.
Points to watch with field observation
- Wind and nearby structures can affect the measured value, so correction is needed.
- Gaps from device contamination or failure must be shown with a quality status.
Read the Rain. Protect What Matters.