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High resolution COPE simulations

High resolution COPE simulations. Kirsty Hanley, Humphrey Lean MetOffice@Reading, UK. COPE. Field campaign to study the production of precipitation in organised convective systems over SW England during July and August 2013. Aims of COPE.

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High resolution COPE simulations

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  1. High resolution COPE simulations Kirsty Hanley, Humphrey Lean MetOffice@Reading, UK

  2. COPE • Field campaign to study the production of precipitation in organised convective systems over SW England during July and August 2013

  3. Aims of COPE • Understand the physical processes involved in convective precipitation. • Improve the representation of microphysical processes in operational km-scale NWP. • Improve the exploitation of data used for operational assimilation. • Leading to improved forecast of convective precipitation that can cause flash flooding.

  4. COPE IOPs Sea breeze

  5. Model setup – UM vn8.2 PS32 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, RHcrit is 0.97 (0.91) in 1st few layers decreasing smoothly to 0.9 (0.8) at ~3.5km. Set of nested models.

  6. 18 July – popcorn convection up to 9km

  7. 25 July – line of showers up to 3km

  8. 29 July – organised convective line over SW peninsula

  9. 3 August – convergence line

  10. 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 maybe produce too much rain. • Lines appear to break up in 200m and 100m model – why? • Are the cells getting smaller a result of the updrafts getting narrower or is it a micophysics issue? • Look at a sea breeze case without precipitation to isolate vertical velocity.

  11. July 5 – sea breeze convergence

  12. July 5 – sea breeze convergence

  13. July 5 – sea breeze convergence FAAM obs Different colours are different times

  14. July 5 – sea breeze convergence 500m UKV Vertical velocity at 325m 13Z 200m 100m Different scale!

  15. July 5 – sea breeze convergence 1000 UKV 0 -0.5 0 0.5 1 1.5 Vertical velocity at 13Z 1000 500m 0 2 -2 0 4 6 1000 200m 0 2 -2 0 4 6 1000 100m 0 -2 0 2 4 6

  16. July 5 – sea breeze convergence 1000 UKV 0 -5 0 5 Westerly wind at 13Z 1000 500m 0 0 -5 5 1000 200m 0 0 -5 5 1000 100m 0 -5 0 5

  17. July 5 – sea breeze convergence

  18. 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? • Compare simulations with lidar and King Air measurements. • Identify key areas of difference between models and observations: • Timing, location, size and intensity of cells.

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