1. © Crown copyright Met Office High resolution COPE simulations Kirsty Hanley, Humphrey Lean MetOffice@Reading, UK

2. © Crown copyright Met Office UKV – 1.5km grid length, 70 levels, 2D subgrid turbulence scheme, BL mixing in vertical. 500m model – 500x400 km 200m model – 300x200 km 100m model – 150x100 km High res models: 140 vertical levels, 3D subgrid turbulence scheme, RH crit is 0.97 (0.91) in 1 st few layers decreasing smoothly to 0.9 (0.8) at ~3.5km. Set of nested models. Model setup – UM vn8.2 PS32

3. © Crown copyright Met Office 18 July – popcorn convection up to 9km

4. © Crown copyright Met Office 3 Aug – convergence line

5. © Crown copyright Met Office 15 Aug – intense warm rain showers

6. © Crown copyright Met Office 25 July – line of showers up to 3km

7. © Crown copyright Met Office 25 July – line of showers up to 3km Scale-aware microphysics package Scheme includes new autoconversion, subgrid variability of cloud & rain, new drop-size distribution. See Boutle et al 2014, MWR for more details.

8. © Crown copyright Met Office 25 July – line of showers up to 3km Ian’s microphysics package New package reduces precipitation but lines still break up in 200m and 100m simulations.

9. © Crown copyright Met Office Summary 1 Saw quite high rainrates from warm rain. Cells appear to get smaller as grid length is reduced – this agrees with work done for DYMECS. The high resolution models produce too much rain. Lines appear to break up in 200m and 100m model – why? More cases can be seen in the report sent out last Friday. Are the cells getting smaller a result of the updrafts getting narrower or is it a microphysics issue?  Look at a sea breeze case without precipitation to isolate vertical velocity.

10. © Crown copyright Met Office July 5 – sea breeze convergence

11. © Crown copyright Met Office July 5 – sea breeze convergence Different scale! Vertical velocity at 500m amsl Extended 200m and 100m domains by 50km to north

12. © Crown copyright Met Office July 5 – sea breeze convergence - Davidstow Lidar data provided by Barbara Brooks

13. © Crown copyright Met Office July 5 – sea breeze convergence - Davidstow

14. © Crown copyright Met Office 11 UTC 14 UTC 13 UTC 12 UTC Angle of 135 ̊ from radar UKV initially moves slower but then speeds up: Between 12-14UTC UKV moves ~10km, high res move ~7.5km

15. © Crown copyright Met Office Sea breeze moves ~8km in 1 hour. ReflectivityVelocity

16. © Crown copyright Met Office July 5 – sea breeze convergence More low cloud in UKV -> lower surface temperatures -> sea breeze convergence moves slower initially.

17. © Crown copyright Met Office July 5 – sea breeze convergence – FAAM obs

18. © Crown copyright Met Office July 5 – sea breeze convergence – FAAM obs

19. © Crown copyright Met Office July 5 – sea breeze convergence – surface obs

20. © Crown copyright Met Office Summary 2 and Future Work Updraft magnitude and width compares reasonably well between the observations and the high resolution models How does cloud width compare? What determines front propagation speed? Roll spacing/depth? Why do high res models break up lines and produce too much precipitation? Compare simulations with other measurements – FAAM, King Air, Radar, Lidar, surface stations. Identify key areas of difference between models and observations: Timing, location, size and intensity of cells. Cases of particular interest: 5 July, 18 July, 25 July, 3 August, 15 August