- Analysis of first ever observations of convective towers from space-borne radars
- Use of constellation of CubeSats for understanding atmospheric processes
- Collaboration with NASA scientists in retrieval methods for convective motions and fluxes
Convective storms are the heart of the Earth’s weather and climate system: they convey most of the transport of water and air from near the Earth’s surface to the upper troposphere, they affect the large-scale atmospheric circulation, they are linked to the Earth’s water budget by producing large amounts of rainfall and they influence the Earth’s radiation budget via formation of widespread high clouds. Though convective vertical transport plays a pivotal role, predictions of current weather and future climates remain limited because the parametrizations of such transport are crude; this represents a major roadblock towards the refinement of weather forecasting and climate models. Global observations of convective vertical mass flux are urgently needed for significant progress to occur.
The launch of the first ever cloud 8-mm wavelength radar on a Cubesat (RainCube) in July 2018 has paved the way towards a new era for space-borne observations of convective systems. The small size (10 cm×20 cm×20 cm), moderate mass (21 kg) and low power (10 W peak power) requirement of the instrument enable constellation missions, which can augment our ability to observe weather systems and their dynamics and thermodynamics down to temporal resolutions of a few minutes, as required for observing developing convection (see Figure 1). This offers a cheaper but unprecedented solution for capturing the storm dynamics. When a constellation of micro-satellites is flying in formation 60-90 seconds apart, time-sequenced profiles of radar reflectivity (Z) separated seconds apart (ΔZ) can be acquired. Together Z and ΔZ/ Δt can be used to provide: (i) the mass fluxes of condensed water mass and dry air and (ii) the rates at which the upper regions of convective storms are moistened. The profiles of Z additionally provide profiles of condensed water (M) in the column and the precipitation falling from convective storms. The radar has demonstrated the maturity of the technology and NASA is planning to launch a constellation of such Raincube to better understand convective processes which remain one of the major roadblocks in the improvement of numerical weather prediction. The challenge now is to use the radar data to produce scientifically relevant results.
Two main activities are envisaged for the PhD project. The first activity will be focused on analysing the data acquired by RainCube looking at specific issues encountered during the in-orbit demonstrator period (e.g. pointing accuracy, calibration, sensitivities, quality of the pulse compression). Secondly, algorithms for water mass and air mass fluxes and for condensate vertical velocity and air vertical velocity will be developed for a mission involving a constellation of RainCubes, currently under study. In addition to the RainCube observations, ultra-high-resolution model simulations of tropical ocean convection using the System for Atmospheric Modeling will be exploited. The student will use such simulations and a forward space-borne Doppler simulator to investigate the ability of a constellation of micro-satellites to study the vertical transport of air and condensate in deep convective clouds.
Training and Skills
This project offers an excellent opportunity to develop and apply novel radar techniques to remote sensing of clouds and precipitation. The student will be trained in a wide range of topics including radar meteorology, cloud physics, radiative transfer and precipitation remote sensing. Applicants should have a science or engineering degree. Knowledge of meteorology would be beneficial. Programming skills in matlab/idl/Python/C/Java/C++ and knowledge of signal propagation and numerical modelling could also be beneficial.
Year 1: Familiarization with radar data, radar forward model simulator, cloud resolving models, precipitation remote sensing.
Year 2: Analysis of RainCube data; development of high resolution datasets of simulations of convective storm.
Year 3: Development of algorithm for water mass and air mass fluxes and for condensate vertical velocity and air vertical velocity. The algorithm will be tested for the simulation database and where possible with aircraft/ground based datasets.
Partners and collaboration (including CASE)
A close collaboration between the Leicester Earth Observation Science group and NASA-JPL is at the core of this project. The Rainradar has been designed at the JPL group led by Dr. Tanelli (International Collaborator). The project will also benefit from collaboration with the group at Stonybrook University, NY, led by Prof. P. Kollias (high temporal resolution numerical simulations and forward modelling). A Collaboration with the European center for Mid-Range Weather Forecast (Dr. R. Forbes) is also envisaged for investigating the potential of the data to validate a global model.
Dr Battaglia is a cloud and precipitation microwave remote sensing expert with more than 18 years of experience in the field, member of the NASA Global Precipitation Measuring mission Science team and Member of the ESA-JAXA Mission Advisory Board. He is based in the Earth Observation Science Group within the Department of Physics (https://www2.le.ac.uk/departments/physics/research/eos/dr.-alessandro-battaglia). He is also member of the National Centre for Earth Observation (www.nceo.ac.uk).
Prof. H. Boesch is the head of the Earth Observation Science Group and Divisional Director of the National Centre for Earth Observation. He is an expert in satellite instrumentation and remote sensing.