Why are there measurement differences between a manual rain gauge and my connected weather station?
Many of you ask us: why are the data from my manual rain gauge not identical to those from my Weenat weather station?
By nature, rainfall is heterogeneous in time and space.
Beyond this starting point, it is perfectly normal to observe differences between measurement tools. Several factors explain these discrepancies:
1. Measurement resolution
A Weenat rain gauge records each bucket tip, corresponding to 0.2 mm of rain. In contrast, a manual rain gauge usually has a precision of 1 mm.
Result: the connected sensor captures finer variations, whereas the manual one smooths the data more.
2. Interpretation of the measurement
- Effects related to timing
The connected rain gauge continuously records each tip (one movement = 0.2 mm) from midnight to midnight.
With a manual rain gauge, readings are taken at variable times (for example, in the morning or evening). Moreover, depending on heat and evaporation, the measured quantity can slightly change.
- Effects related to reading
With a manual rain gauge, the reading also depends on the viewing angle. A small optical effect can therefore modify the interpretation.
The connected rain gauge eliminates this bias by automatically recording each movement.
- Effects related to intense weather events
Storms and wind can also explain measurement differences. Storms, due to their irregular distribution, and wind, which changes the trajectory of the rain making it oblique, can both lead to measurement losses or errors.
3. Installation of the rain gauge
A manual rain gauge is often placed on the ground or on a window ledge.
The Weenat weather station, on the other hand, is installed at least 1 meter above the ground, in accordance with Météo-France recommendations.
This placement reduces concentration or filtering effects of rainfall.
To sum up: manual or connected, they are two different ways of collecting data, which explains why you observe differences between the two instruments.
We would also like to remind you that proper maintenance of your rain gauge ensures more accurate measurements 🤓.
To go further, check out the short video from our Weather Expert, Emmanuel Buisson, who explains this topic.
Why do I observe differences between the history, the measurement of my connected rain gauge, and the weather model data?
Several factors explain these differences: the technology used and their spatial representativeness.
Technologies used by meteorological organizations
Organizations such as Met Office rely on complex and complementary tools:
- Satellites
They provide a global view, ideal for remote or hard-to-access areas (such as oceans). Being outside the atmosphere, however, they can introduce biases related, for example, to the presence of clouds.
- Radars
Arranged in a network with spacing of up to 300 km between each radar, they measure rainfall intensity per km² every 5 minutes. The closer the observation is to a radar, the more reliable it is. These measurements provide a representative overview on a territorial scale.
- Weighing rain gauges
Installed on site, they directly collect rain on their surface. This technology is more reliable and precise but also more expensive.
Connected rain gauges
On their side, connected sensors like those from Weenat use simpler, reliable, and accessible technologies, such as the tipping-bucket rain gauge.
Their advantage: providing fine and precise measurements directly at the scale of your plot, while being easy to maintain.
Emmanuel Buisson, our weather expert, explains it all in this short video 📽️
My sensor is no longer receiving data
Several reasons may explain why your Weenat sensor is not transmitting data:
- Network coverage in the area where the sensor is installed
- Obstacles between the sensor's antenna and the network antenna
- A depleted sensor battery
- A sensor malfunction (due to a fall/breakage or a component failure)
If you notice this issue, we recommend checking the following:
- Ensure your sensor is still linked to your Weenat account
- Verify that the battery is less than two years old
- Check that the casing has not been damaged
- Make sure the antenna is properly screwed in and free from any obstructions (such as vegetation, crops growing taller than the antenna, trees, etc.). It is also advisable to space sensor antennas at least 50 cm apart and avoid clustering them in one location.
If none of the above issues seem to be the cause, we suggest resetting your sensor. Simply pass a magnet over the diode located on the right side of the casing and check that it lights up red. (Note: If it's sunny, the diode light may be difficult to see.)
If your sensor still does not transmit data, our customer support team is here to help at support@weenat.com. Feel free to send them one or more photos of your sensor’s installation and surroundings, as well as a summary of the checks and actions you have performed. This information will help us with our analysis.
My data is incomplete, and I have gaps in my history
Two main reasons can explain why your Weenat sensor is only transmitting data partially:
- Network coverage in the area where the sensor is installed
- Obstacles between the sensor's antenna and the network antenna
If you experience this issue, we recommend following the checks and actions outlined above.
My sensor's GPS position is not updated
Weenat sensors are programmed to send their GPS position every 7 days. We recommend waiting one week for the next GPS update.
However, you can manually force a GPS reset by passing a magnet over the diode located on the right side of the sensor until it turns red. This operation must be performed outdoors. If the network signal is weak, you may need to repeat the process.