WesCon – Observing the Evolving Structures of Turbulence (WOEST)

Our understanding of turbulent processes in the atmosphere is largely derived from theory and large eddy simulations (LES). There have been very few observations designed to evaluate the turbulent processes that are important for convection.  

The Wessex Convection Experiment (WesCon) aims to address this gap using a range of ground-based instruments, the FAAM aircraft, and limited use of the Chilbolton Advanced Meteorological Radar (CAMRa). WesCon – Observing the Evolving Structures of Turbulence (WOEST), will complement WesCon by: 

• capturing the vertical and horizontal spatial variability and evolution of the boundary layer;  
• obtaining 3D estimates of small-scale turbulence and larger-scale turbulent coherent structures in convective clouds; and  
• supporting the WesCon model evaluation and development, including by providing novel retrievals of turbulent and dynamic processes. 

The research will enhance the WesCon campaign by observing turbulent and dynamic processes at sub-km length scales and at a frequency down to 2 minutes or less, enabling a process-oriented evaluation of moist convection and boundary-layer evolution. The approach combines a pair of steerable research-grade Doppler radars with innovative adaptive scanning strategies that enable scanning the same convective cloud targeted by the FAAM aircraft at 2-minute intervals. Two additional X-band Doppler radars will provide excellent coverage of the research domain in southern England, capturing the 3D evolution of convective-cloud dynamics at 5-minute intervals. An additional supersite at Chilbolton will host additional instruments including a new Raman lidar, UHF radar wind profiler and a new array of cloud cameras, to study turbulence in the boundary layer and its influences on convective cloud development.  

Through supporting two mobile radiosonde stations, and drone capability, analysis of moist convective turbulence and boundary-layer evolution will be placed in the context of variability in the pre-convective environment. The observations will lead to new understanding of the variability of turbulence and cloud dynamics from 10m-1km scales and of the variability and evolution of the boundary layer in the context of the surrounding cloud field, both of which will enable new evaluation approaches for sub-km grid-length numerical weather prediction (NWP) models.