1 / 14

Stephan de Roode (KNMI/IMAU) Simon Axelsen (IMAU) Pier Siebesma (KNMI)

The role of the mean relative humidity on the dynamics of shallow cumuli - LES Sensitivity experiments. Stephan de Roode (KNMI/IMAU) Simon Axelsen (IMAU) Pier Siebesma (KNMI). Large-eddy simulation - The BOMEX shallow cumulus case.

anka
Download Presentation

Stephan de Roode (KNMI/IMAU) Simon Axelsen (IMAU) Pier Siebesma (KNMI)

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. The role of the mean relative humidity on the dynamics of shallow cumuli - LES Sensitivity experiments Stephan de Roode (KNMI/IMAU) Simon Axelsen (IMAU) Pier Siebesma (KNMI)

  2. Large-eddy simulation -The BOMEX shallow cumulus case

  3. LES sensitivity experiments - Set-up analogous to Derbyshire's EUROCS deep convection case

  4. Results for cloud core : mass fluxAll averages taken over the 3rd hour

  5. Results for cloud core : vertical velocity and core fraction

  6. Mixed parcel diagram -Buoyancy reversal

  7. Buoyancy reversal - Dependency on mean vertical gradients G 1.0 0.0 De Roode, 2004

  8.  and fractional entrainment rate.Diagnosis from LES results.

  9. Kain & Fritsch parameterization- Assume flat PDF for ce = e02 (Bretherton et al. 2004)

  10. Bowen ratio, convective velocity scale w* and mass-flux

  11. Bowen ratio, convective velocity scale w* and mass-flux

  12. Conclusions • Set I - Change relative humidity, but keep mean buoyance the same • Cloud fraction changes => • Mass flux changes • Set II - Change Bowen ratio, but keep surface buoyancy flux the same • Cloud fraction changes => • Mass flux changes (also at cloud base)

  13. Results for cloud core : fractional entrainment and detrainment

  14. c* from LES

More Related