Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Forecasting rain - Radars for estimating rainfall rates

To be effective, flood warning systems use rainfall data available in real time. These data come from the ground observation network and estimations made based on the national network of climate radars operated by Météo France.

Today, mountain zones are only partially covered by this rain detection technology. Within the INTERREG project, a new generation of radars is being tested by Cemagref in the Var department, a mountainous region with a high flood risk. The radar is currently located in the countryside immediately inland from Nice.

Measuring the intensity of rain as it is falling is indispensable to anticipating rapidly rising waters and reacting to the associated flood risk. To the classical rain gauges installed throughout the area, new radar technologies were added in the 1990s to detect rain and measure the accumulation of precipitations in real time.

Today, Météo France has a national network of 24 weather radars available within approximately 100 km. However, all regions in France are not covered by this mesh, in particular the mountain zones where the relief masks downstream rain zones by creating an obstacle to wave displacement. Within the FRAMEA1 project, a new radar technology developed by Novimet ² is being tested at the Aix-en-Provence Cemagref. The experiments conducted in the Maures massive have proven to be highly promising.

[1 Flood forecasting using Radar in Alpine and Mediterranean Areas (FRAMEA)]
[2 A young company split off from the CNRS]
- More compact and less expensive radars
The radars used at the beginning to monitor planes flying overhead were extended to the detection and quantification of precipitations. Large-scale radars, 6–8 m in antenna diameter, are used today in weather stations located in the plains. In mountain zones, the number of radars must be multiplied in relation to the relief, which requires smaller and less expensive models. The new Hydrix radar responds to these demands. However, by reducing the diameter of the parabolic antenna to 1.5 m, the wave frequency must be boosted, which increases the attenuation of waves during their displacement.

To compensate this signal attenuation effect, a profiling algorithm (ZPHI) is used. Finally, the radar operates in double polarization, which provides information on the size of the rain drops and estimates precipitations without resetting ground network observations. Today, in a doctoral dissertation supervised by both Cemagref and the firm Novimet, this new radar technology is being tested in the Var department, a mountainous region that experiences very intense flash floods.

- Results that are coherent with ground readings

The Hydrix is installed near Réal Collobrier, Cemagre’s instrumented research catchment, located in the Maures massif. The total rainfall in autumn 2006 calculated by the radar was compared to the rain gauge readings on the ground and to the accumulation estimated by one of the nearby radars belonging to the Météo France network. Within a 60- to 80-km radius, the data supplied by the radar were in coherence with the quantities of rain collected on the ground. In addition, the algorithmic signal processing retransmitted rain gauge data in real time that were as good quality as the data sent by the classical radar managed by Météo France.

Today, the research is continuing so as to integrate the rain gauge data supplied by the radar into existing rainfall-runoff models. By converting rainfall into runoff, these mathematical tools can calculate the runoff of rivers at the outlet of a catchment. These rainfall and runoff data then feed the flood warning systems, such as the Aiga system developed by Cemagref and Météo France in 2005. By completing the existing radar network, the Hydrix technology will contribute to the extension of the flood warning system over the entire area, including mountainous zones.

Marie Signoret | alfa
Further information:

More articles from Ecology, The Environment and Conservation:

nachricht Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel

nachricht Removing fossil fuel subsidies will not reduce CO2 emissions as much as hoped
08.02.2018 | International Institute for Applied Systems Analysis (IIASA)

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1

In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.

Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...

Im Focus: Alliance „OLED Licht Forum“ – Key partner for OLED lighting solutions

Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.

They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...

Im Focus: Mars' oceans formed early, possibly aided by massive volcanic eruptions

Oceans formed before Tharsis and evolved together, shaping climate history of Mars

A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...

Im Focus: Tiny implants for cells are functional in vivo

For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.

In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...

Im Focus: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

Latest News

TRAPPIST-1 planets provide clues to the nature of habitable worlds

21.03.2018 | Physics and Astronomy

The search for dark matter widens

21.03.2018 | Materials Sciences

Natural enemies reduce pesticide use

21.03.2018 | Life Sciences

Science & Research
Overview of more VideoLinks >>>