Overview
The CLEOPATRA project aimed at developing a SW procedure able to simulate relevant weather phenomena as they appear to airborne weather radars, starting from a high level description of the weather phenomenon (scenario), up to obtain the polarimetric I/Q signals at radar output. Such data have to be used as input to processing system simulation software (outside the scope of the present work) to be developed as test bench to compare the performances of new improved weather detection algorithms with older ones.
The following main issues were considered:
- Meteorological modelling (scenario definition)
- Electromagnetic modelling (backscattering from hydrometeors)
- Weather radar modelling (including clutter, antenna effects etc)
having in mind the goal of developing a new class of simulators, able to combine the description of the meteorological scenario at mesoscale level (typical of the environment simulators) with the capability of generating accurate time series of raw signals (typical of the microphysical simulators), while keeping complexity and computational effort manageable. The procedure was “validated” by referring at experimental data coming from a ground-based weather radar.
Funding
Results
Executive Summary:
Radar simulators which are able to accurately reproduce the signal coming from a synthetic environment are powerful instruments for the assessment of the performance of new radar systems. In this document we described a new airborne meteorological radar simulator, namely CleoSim (Cleopatra Simulator), which combined the description of the meteorological scenario at mesoscale level with the capability of generating accurate time series of raw I/Q signals.
CleoSim was developed in the frame of the Cleopatra (CLEaner OPeration Attained Through Radar Advance) project. It wass able to simulate the polarimetric I/Q signals for most significant weather phenomena (both threating and non-threating events for aviation safety) as they appear to the airborne X-band weather radars. From such I/Q signal all of the radar observables (absolute and differential reflectivity, Doppler spectrum) can be derived through proper post-processing.
The following main topics had been addressed in the frame of the Cleopatra project:
- Meteorological modelling: all meteorological events are described in terms of 3D distributions of mesoscale parameters (temperature, water content, snow content, graupel content)
- Electromagnetic modelling: according to both their nature and related mesoscale data, droplets/hydrometeors are characterized in terms of backward and forward propagation complex amplitudes.
- Microphysical modelling: according to both their nature and related mesoscale data, droplets are assigned a PSD (Particle Size Distribution) and terminal fall speed;
- Weather radar modelling: polarimetric I/Q signals are computed according to droplets/hydrometeors electromagnetic and microphysical properties and according to the underlying terrain morphology and nature.
The project team was composed of four partners, providing all required technical expertise:
- IDS, Ingegneria Dei Sistemi S.p.A has been working since 1980 in modelling complex physical phenomena, with particular reference to electromagnetic and radar applications. IDS currently develops and commercializes multi-language, multi-platform CAE tools.
- POLIMI, Politecnico di Milano is a reference in the scientific community for electromagnetic modelling of weather phenomena (backscattering, attenuation, propagation), as seen from weather radar point of view.
- RCF, Rockwell Collins France is one of the international leaders in the field of airborne weather radar equipment. RCF provided deep knowledge of present and future trends about radar architectures and applications.
- KNMI, Royal Netherlands Meteorological Institute, is one of the main European institutes for meteorological modelling and measurements. Therefore KNMI represented the reference point for scenario definition.