1. COPE: The COnvective Precipitation Experiment. Met Office interests
Phil Brown
26/10/2012

2. Table of Contents
Aims
Background
Modelling
Summary

3. Aims and Background

4. Aims of COPE
To study the production of precipitation in organized convective systems over SW England
To improve the exploitation of data used for operational assimilation
To improve the representation of microphysical processes in operational km-scale NWP
Leading to the improvement of quantitative precipitation forecasts

5. Some science questions
What are the impacts of large- and meso-scale dynamics on convective precipitation?
What is the representivity of line-of-sight Doppler winds from network radars and what can we learn to improve the way they are assimilated?
What is the role of supercooled rain in the growth of precipitation in UK summertime convection?
Which ice nucleation processes are active in these clouds, and why is -10C a magic number?
What are the impacts of aerosol changes on precipitation formation and how well are these represented in the UM?
Does the UM generate realistic precipitation-driven downdrafts and cold pools? Does it evaporate rain correctly?
What are the relative importances of resolution, microphysics and other sub-grid processes in producing good forecasts?

6. Background: Boscastle floods, 16 Aug 2004
Meteosat, high-res visible
1530Z
1130Z
Convergence line over N.Cornwall
Downdrafts triggering new convection
1330Z
1530Z

7. Background: Boscastle floods, 16 Aug 2004 Golding et al
Background: Boscastle floods, 16 Aug Golding et al., 2005, Weather
High accumulations resulted from intensity and duration of precipitation
Slow-moving cells organized in along-wind lines
These were not spectacular convective clouds – tops probably reaching -15 to -20C
Significant involvement of both warm-rain and ice-phase processes
New convection triggered by downdrafts

8. Background: ICEPIC B200, 18/05/2006
Lack of precip in the upwind end of shower line – probably warm rain
Excessive precip rates from cells further downwind – probably ice-phase

9. Background: ICEPIC B200, 18/05/2006
Region of flight operations, Z
UM – 4km
UM – 1.5km
Radar

10. Background: ICEPIC B200, 18/05/2006
Liquid
-10 -5 +5
-10 -5 +5
-10 -5 +5
-10 -5 +5
Ice
-10 -5 +5
-10 -5 +5
Rain
Tracking single cells in a 1.5km UM simulation

11. Background: ICEPIC B200, 18/05/2006
Insufficient warm-rain in early stages of cloud growth
Excessive precipitation rates following onset of ice-phase
Ice-phase transition occurs very rapidly in 1.5km model – within 10 min
similar to Phillips et al. (2001) LES study of orographically-triggered convections
Aircraft observations continue to show largely unglaciated updrafts
Resolution or microphysics?

12. Modelling

13. Models UKV UKV Ensemble (2.2km) resolution High-resolution UM
36hr forecasts every 6hr
3D-VAR
UKV Ensemble (2.2km) resolution
High-resolution UM
100m resolution for case studies
Nowcasting Demonstration Project
1.5km resolution
12hr forecasts every hour
4D-VAR

14. NDP domain Focus on Olympics sites and period, 2012
Doppler weather radars in S.England
1.5km resolution
Run every hour, for 12hr duration
4D-VAR with sharper error covariance matrices
NDP UKV

15. NDP: 29/08/ Z cycle T+8

16. Questions and answers