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Convection plans Alison Stirling.

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Presentation on theme: "Convection plans Alison Stirling."— Presentation transcript:

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?

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