1 / 17

Dynamics of Subsiding Shells in Actively Growing Clouds with Updrafts

Explore link between aerosols and droplets in clouds. Study descending shells at cloud boundaries and their characteristics. Develop simulation setup to analyze shell behavior. Non-classical self-similar flow. Velocity predictions compared to observations.

worley
Download Presentation

Dynamics of Subsiding Shells in Actively Growing Clouds with Updrafts

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Dynamics of Subsiding Shells in Actively Growing Clouds with Updrafts Vishnu Nair1, Thijs Heus2 and Maarten van Reeuwijk1 1 Department of Civil and Environmental Engineering, Imperial College London, UK 2 Department of Physics, Cleveland State University, USA

  2. Introduction • Shallow cumulus convection is one of the most important unresolved processes in a Global Climate Model. • Lateral mixing and entrainment at cloud boundaries are dominant contributors towards cloud dilution and hence lifetime. • Mixing at cloud edges results in the formation of a descending shell (Heus and Jonker 2008) • Pre-conditions the properties of air entraining and detraining air • Downward flux compensates the majority of the upward flux in the cloud core Small et al 2009 2/15

  3. Aim • Ultimate aim of COMPLETE is to investigate the link between aerosols and droplets in clouds • Imperial is responsible for carrying out idealised direct simulations of cloud boundaries • Our final aim is to use a fully coupled droplet model • First objective : to develop a suitable simulation setup to study descending shells at cloud boundaries 3/15

  4. Numerical Simulations 4/15

  5. Governing equations • With the buoyancyb (~virtual potential temperature) defined as (Liquid water potential temperature) (Total water specific humidity) 5/15

  6. Simulation details • Grid: 3072 x 1536 x 1536 • Taylor Reynolds number, • Resolution, • Core updraft velocity, • Cloud buoyancy, 6/15

  7. Animation 7/15

  8. Mean buoyancy and mean vertical velocity 8/15

  9. Shell area 9/15

  10. Self-similarity of shell 10/15

  11. Characteristic flow scales 11/15

  12. Self-similarity of shell – TKE budget Not a classical self-similar flow! 12/15

  13. Universality of the shell 13/15

  14. Conclusions • Developed a case-setup to study descending shells at lateral cloud boundaries • Shell thickness increases linearly with time and accelerates ballistically • Non-classical self similar flow: • The appropriate characteristic scales are based on buoyancy • Shell velocity is dynamically unimportant • Shell thickness and minimum vertical velocity predictions give values comparable to observations 14/15 Nair et al. (2019), Dynamics of Subsiding Shells in Actively Growing Clouds with Vertical Updrafts, JAS (under review)

  15. Sneak preview – Lagrangian particles and droplets 15/15

  16. Acknowledgement • This project has received funding from the Marie-Sklodowska Curie Actions (MSCA) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no 675675).

  17. Questions?

More Related