1. © Crown copyright Met Office From the aircraft to climate prediction Anthony Baran, Met Office, Exeter, UK. OBR conference, December 2012

2. © Crown copyright Met Office Contents This presentation covers the following areas The problem – apart from the aircraft and ground-based measurements ! Why are ice crystals so perverse? What we need to know about how ice scatters radiation Putting what we know about how ice scatters into the climate model Does better physics = better NWP & climate model ? Discussion

3. © Crown copyright Met Office The problem

4. Thanks to Kirsty and Joss Kent

5. Observed reflected solar radiation DJF- 2007 – University of Lille

6. © Crown copyright Met Office Occurrence of Cirrus Sassen et al. (2008)

7. © Crown copyright Met Office Why are ice crystals so perverse?

8. Tropical Example, A. Heymsfield Fresh Anvils, Um and McFarquhar 2008. University of Manchester

9. © Crown copyright Met Office Generalise Number Concen Ice crystal maximum dimension Baran & Labonnote (2007)

10. What we need to know about how ice scatters radiation © Crown copyright Met Office

11. Asymmetry parameter, g Extinction,  ext Single Scattering albedo,  0

12. Put what we know about scattering into the climate model © Crown copyright Met Office

13. IWC, T c Consider an ensemble of ice crystals Number Concen D m Number Concen D m sum everything IWC (Conserved) g,  ext,  0 aircraft

14. Relate optical properties to IWC & Temp  0 and g at an absorbing wavelength Climate & NWP model

15. Does better Physics = Better NWP & Climate model © Crown copyright Met Office

16. Comparing the climate and NWP models against space- based solar observations Old optical propertiesEnsemble optical properties Differences in the ten year mean between model and observations of reflected solar radiation Climate models are actually worse than we thought ! Better physics  better climate model

17. What about the high-res NWP model? Obs OLD Ensemble High-res model is better ! Better physics = better NWP model

18. © Crown copyright Met Office Discussion