Spaceborne doppler radars in convection: performance of EarthCARE and beyond
thesisposted on 29.06.2015, 11:48 by Tomasz Michal Augustynek
The thesis concerns the assessment of the performance of the upcoming Earth Cloud Aerosols Radiation Explorer (EarthCARE) Doppler cloud profiling radar in convection. Spaceborne Doppler radar data are simulated starting from high-resolution CRM model data, through forward Monte Carlo simulation from which the voltage signals as sampled by specific radar configuration are generated. Until the launch of Earth- CARE in 2016, simulations are the only means of assessing the impact of EarthCAREs configuration on the accuracy of the Doppler products (reflectivity and mean Doppler velocity). Two of the main contributors to EC-CPR total error budget are the multiple scattering and non-uniform beam filling effect errors, which can be mitigated using methods described in the thesis. However, for Earth- CARE radar using the conventional pulse pair technique, the scientific requirement for accuracy of 1 m/s at 1 km integration of Doppler velocity cannot be met for deep convective systems, even if the correction methods are applied. The thesis then focuses on six polarization diversity radar systems, three for W-band (94 GHz) and three for Ka-band (35 GHz). After the correction methods are applied for MS and NUBF effects, the accuracy of 1 m/s for 500 m integration is possible for all W-band configurations assessed. This includes relatively small antennas of 2.5 m currently being implemented in space. Consequently, two key results for measurements in deep convection can be drawn for future radar concept design. Firstly, the large antenna will help to minimize the effects of non-uniform beam filling and multiple scattering. Secondly, the polarization diversity can solve the problem of aliasing of velocities.