1. Convection plans
Alison Stirling

2. Priorities for convection parametrization
Main Systematic Errors:
Diurnal cycle
MJO
Monsoons
AEW coupling
Transient response
to boundary layer
Feedback with
`large-scale’
environment

3. Interaction with large scale
Ascent generates CAPE
Heating generates ascent
Depth and amplitude of convective response key to improving monsoon, MJO, AEW coupling

4. Interaction with large scale progress and further work:
Increased entrainment improves
coupling between convection and
large-scale (Klingaman et al 2013)
…but it can’t be
high all the time…
Introduce physically realistic
entrainment dependence:
(stability and cloud area)
Explore effects of large scale on other parts of scheme
UM high resolution convection simulations over a large domain allows circulations resulting from convection to develop.

5. Interaction with boundary layer
Introduce energetics of boundary layer thermals
Modify triggering and closure to have dependence on this
Cold pools
Important for:
1. Triggering and closure
Additional KE to overcome CIN
Temperature and moisture differences
allow CAPE to be present locally even when the mean state is stable
Enhanced lifting
2. Entrainment
affects cloud area
(and therefore buoyancy
and vertical velocity)
Two zones of temperature and moisture
Requires memory of previous precipitation events
MOAP secondment to work on cold pools

6. Research areas 1. Entrainment / detrainment
Dependence on cloud area
Dependence on stability
Adaptivity
2. Interaction with large scale
What is the profile of ascent caused by convective heating?
How does ascent affect closure and at what levels is it important?
3. Interaction with boundary layer
Representing energetic response to CIN
Representing cold pools
4. Memory
Relative importance of cloud area, rh variability, BL variability
Prognostic for cloud area
5. Closure
How do surface processes and upper level processes combine?

7. Higher resolutions Convection position available!
See
Closing date: 14th July 2013
Higher resolutions
Mass flux: Separate into component parts
vertical velocity, cloud area, and cloud number
Multiple plume: Quantify the need for a multi-plume approach
Allows:
grid-size sensitivity,
inclusion of microphysics
better coupling with PC2
stochasticity
Applications submitted for Reading and Leeds CASE students to work on different aspects of grey-zone problem.

8. Questions and answers

9. Unification
Give each component of the existing convection scheme an improved physical basis.
Entrainment: Include dependence on stability and cloud area
Detrainment: Reformulate to be adaptive all the way up the cloud, and let the level of adaptivity depend on cloud area
Triggering and closure: Base on energetics of boundary layer processes and large-scale ascent

10. Unification details Research areas include: Cloud area representation
Cold pool representation
Boundary layer thermal energetics
Convective response to large-scale ascent

11. UM run Stu Webster Indian Ocean 200m from 2.2km b.c.s
4000 x 2600 points
3 days

12. What controls convective depth?
Vertical extent of CAPE
Entrainment
Detrainment
Cloud area?
Boundary layer processes? (e.g. cold pools)
High entrainment increases coupling to LS ascent/ descent, but it can’t be high all the time!

13. What controls heating amplitude?
Rate of CAPE creation?
Closure
Inversion removal?
Ascent?