1. Snapshots of WRF activities in the GFI/Iceland groups

2. DLR / Bernadett Weinzierl Layering Observations from DLR research aircraft near Eyjafjallajökull

3. Lidar from the DLR flight across the plume on its way from Eyjafjallajökull to Scotland Strong stratification (layering)

4. WRF with horizontal resolution of 9 km FLOW

5. WRF with horizontal resolution of 3 km Hálfdán Ágústsson and Haraldur Ólafsson, 2010.

6. Permanent lowering of the flow level Vertical mixing in a 3000 m deep layer Vertical mixing at higher levels due to mountain waves FLOW None of these important features are visible at dx=9km, or at resolutions of many current forecast models! WRF with horizontal resolution of 1 km Hálfdán Ágústsson and Haraldur Ólafsson, 2010.

7. The model underestimates the sharpness of the inversion, and all smaller details above it MODEL OBSERVATIONS Keflavík http://belgingur.is

8. High concentrations of ash occures several times in Reykjavík, after the end of the eruption

9. Very clear source

10. Simulated surface flow http://belgingur.is

11. Simulations of winds at the source of the dust (ash) m/s at the source Horizontal resolution (km)

12. 1) 2) 3) 4) The FLOHOF field experiment

13. 1) 2) 3) 4) By far largest errors: Downslope winds Jonassen et al

14. The the horizontal extension of the downslope winds is highly non-stationary

15. The SUMO model aircraft for meteorological observations Photo: Haraldur Ólafsson

16. No extra observations With in-situ obs. with a model aircraft A major difference in flow pattern extending far above mountain top level 23 km Wind speed, ranging from 0 to 12 m/s Vertical section of simulated flow across mountain

17. 1) 2) 3) 4) A study of turbulent fluxes inn Spitzbergen (Kilpelainen et al., Tellus – in press)

18. Dynamics of extreme precipitation in Central Norway (Steenesen et al. subm. to Tellus)

19. Tveita et al. MAP, in rev. 19 Case studies Dynamics of mesoscale winds WSP10m (CTRL-NOGREEN) +24h 5 March 2000 18UTC Frontal jet off shore Cape Tobin jet Pattern NE of Iceland Wake Prominent features

20. Using the WRF fields to calculate the surface gusts by the Brasseur method Ágústsson & Ólafsson, MAP, 2009

21. Predictability studies: Analysis of the dynamics of forecast errrors Tveita, Olafsson, Sandvik & Hagen, MAP – in revision Hagen, Olafsson, Sandvik & Tveita, MAP – in revision Steenesen, Olafsson & Jonassen, Tellus, submitted

22. RESULTS - FORECASTING C: LEAD TIME increased lead time => decrease in forecast quality the decrease is quite regular for all the four cases and for most steps however, some steps are larger than the others, e.g. 72 h lead time to 96 h lead time for the 10 November 2006 case.

23. ~5 K warmer in GOOD than in BAD Temperature difference =>difference in mean sea level pressure DIFF (GOOD-BAD) MSLP GOOD: 0h BAD: +24h Black line: track of slp anomaly originating east of Hudson Bay Red line: track of another slp anomaly DIFF (GOOD-BAD) in θ 850 RESULTS - FORECASTING