Understanding the Lid on a Murky Caldron: Using Polarised Doppler Weather Radar Observations to Improve Our Understanding of the Impact of Stratiform Clouds that Cap the Boundary Layer
This PhD project will utilise the latest developments in dual-polarisation radar technology to explore novel ways of understanding the role of microphysics in stratiform clouds in the formation of polluted boundary layer conditions over the UK.
Project Summary Polarization is the phenomenon in which waves of electromagnetic radiation are restricted in direction of vibration. The reason polarization state is worth contemplating in relation to the clouds is that two beams of radiation, otherwise identical, may interact differently with matter if their polarization states are different. Thus, observing the polarization of scattered light in the atmosphere provides a unique way to probe clouds, precipitation and aerosol.
In this project, you will have the opportunity to explore the use of dual-polarisation radar to make novel polarimetric observations of stratiform clouds. To accomplish this you will utilize the recently upgraded UK weather radar network, the NCAS mobile X-band dual-polarisation Doppler radar (located at the University of Leeds) and NCAS’s new mobile polarised Doppler Ka-band radar (located at the Chilbolton Observatory) to investigate the wealth of unexplored information provided by polarimetric variables. You will use these new observational capabilities to improve our understanding of how the microphysics of stratiform clouds impacts the boundary layer below. In particular, you will examine how certain microphysical conditions stratiform clouds lead to varying vertical temperature inversions and ultimately trap pollution in the boundary layer or lead to the formation of drizzle that helps clean pollution from the air. You will also explore how these experimental observational techniques may be incorporated into improving operational observational and prediction systems.
Project Objectives: This project will significantly contribute to the field of radar polarimetry, with specific applications to polarimetric classification of winter weather hydrometeors. In this project, you will work with world leading scientists at the University of Leeds and NCAS to:
1. Become an expert in collecting and analysing dual-polarisation Doppler radar observations. This will be in part accomplished by having hands on experience with NCAS’s mobile dual-polarisation Doppler X-band radar and NCAS’s new polarised Doppler Ka-band radar.
2. Make use of the full range polarimetric radar observations (including the multiple sources of radar observations described above and the full set of observable polarimetric parameters) to determine and quantify the evolution of hydrometer size, concentration, phase, shape, and orientation in stratiform clouds across the UK. This will be achieved by utilising a hydrometeor classification scheme to analyse the observations.
3. Use the radar observations in collaboration with ancillary information about the thermodynamic and dynamical structure as well as composition of the boundary layer below these clouds (i.e. radiosondes, surface meteorological stations that include observations of temperature, humidity, wind speed and direction, pressure, solar radiation, and soil temperature and humidity, boundary layer wind profilers, a Raman temperature and humidity lidar developed by the project PI, turbulent heat and moisture flux systems and air quality observations) to examine the impact various stratiform cloud formations have on the structure of the boundary layer.
4. Use polarimetric radar observations to evaluate and improve the representation of stratiform cloud microphysics and impact these clouds have on the boundary layer in a high resolution numerical prediction model. This objective will be accomplished by implementing and validating a radar forward operator that utilises the output of the Met Office’s UKV.
One unique aspect of this project is that you will be trained to go into the field and make observations with the new NCAS X-band and Ka-band radars (i.e. you will have a direct hands on experience in deploying and operating a state-of-the-art instrument). The observations you make with this instrument will provide the basis of your exploration in the use of polarimetric radar observations, though the total fieldwork component of the project may vary depending on the role of the radar in upcoming field campaigns and your interest.
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FTE Category A staff submitted: 79.20
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