Exploitation of Satellite-To-Earth Microwave Links to Estimate Rainfall

Droughts and Floods – Adaptation to Extreme Events in a Hotter Climate 2019 IMPEL Water and Land Conference

Rome, Italy - 8 October, 2019

Exploitation of satellite-to-earth microwave links to estimate rainfall

D.D. Caviglia, L.G. Lanza, M. Colli, M. Stagnaro, and A. Delucchi

1 University of Genova WMO Lead Centre B.Castelli PROJECT RATIONALE

Technological innovation: Exploiting the propagation model of microwave signals to estimate the amount and distribution of rainfall at river basin level Deployment of a distributed system of measurement and localization of precipitation in real time Main purpose: Allow a timely evaluation of the onset of weather-hydrological alarm conditions due to intense rainfall Recipients: Entities responsible for forecasting, monitoring and surveillance of the weather-hydrological risk for civil protection Results: Reduction in the time required by the management and dissemination of alarms in the territory Timely information for a controlled evacuation

2 Features and Functionalities

Features : – Data acquisition and processing in real time – Analysis on a local scale, at the level of river basin – Using the commercial TLC network for the connection between sensors and the central system – Use of the Internet and mobile channels for the dissemination of results Functionalities: – Real-time measurement of rainfall rate (in mm/h) for each acquisition sensor. – Construction of a map of the space-time distribution of rainfall

3 SYSTEM ARCHITECTURE 1/4

4 SYSTEM ARCHITECTURE 2/4

5 SYSTEM ARCHITECTURE 3/4

Network tailoring: – Depending on the orography of the territory the network is designed for the best combination of:  Layout of the Measurement sites  Number and direction of antennas at each site

to optimize the coverage of hydrographic basins

6 SYSTEM ARCHITECTURE 4/4

to optimize the coverage of hydrographic basins

7 SENSOR UNIT (1/2)

8 SENSOR UNIT (2/2)

1) Decoder interface; 2) DC/DC converter (13/18 V to 5 V); 3) 75/50 W directional coupler; 4) LNA; 5) L-band BP filter; 6) LDO for the analog circuitry; 7) Power detector.

8 RAIN ESTIMATION APPROACH (1/4)

Satellite (Constellation): • Eutelsat Hot Bird 13B/13C/13D @ 13.0°E – Distance: 37886 km – Elevation: 38.7° – Azimuth (true): 174.2°

9 RAIN ESTIMATION APPROACH (2/4)

10 RAIN ESTIMATION APPROACH (3/4)

Melting layer

Earth projection

Earth path where rain rate is estimated

11 RAIN ESTIMATION APPROACH (4/4)

Experimentation: Collecting sets of measures in the UNIGE laboratories in various weather conditions

Prototype validation: Through the comparison between the measurements of the Smart Rainfall System and those of a reference rain gauge, under different atmospheric The example shown refers to the early hours of the 31-08-12 conditions The peak of the pluviometer (red line) is of about 10 mm in 30 mins

Conclusions: The Smart Rainfall System, operating in real time, anticipates up to 30 mins the results of the rain gauge The measurements of the two instruments are strongly correlated The Smart Rainfall System even detects light rain (tenths of mm/h)

The integral of the extent of the Smart Rainfall System is consistent with what obtained with the rain meter 12 SRS – GENOA EXAMPLE GENOA: 21/11/2016 | 08:00 – 08:15

SEQUENZA ANIMATA FIELD EXPERIMENT (1/4)

Genova, the experimental set-up

13 FIELD EXPERIMENT (2/4)

Reference rainfall intensity vs Specific Attenuation

14 FIELD EXPERIMENT (3/4)

Reference vs. SRS 10-min rainfall amount

14 FIELD EXPERIMENT (4/4)

Linear correlation between reference vs. SRS 1-min rainfall intensity

)

(

coefficient

correlation Linear Linear

14 FUTURE DEVELOPMENTS

- SRS microwave satellite link technique can be used to provide real-time information on the rainfall rate spatially averaged along the rainy portion of the link path. - As a next development, the level of the melting layer must be assessed close to the real time in order to implement a network of SRS sensors for real-time monitoring of precipitation fields. - In addition, we are planning to investigate the effect of the type of precipitation and particle size distribution on the scattering parameters by means of field observations made by disdrometers. - Finally, we are comparing the measurements made by a large network of microwave links in the city of Genoa against the regional weather RADAR maps to assess the addressable accuracy of rainfall maps performed basing on satellite microwave links. THANK YOU FOR YOUR KIND ATTENTION !

Daniele Caviglia [email protected] [email protected]