1. BAe-146 GV Global Hawk CAST flight planning and analysis using NAME- Jan-Feb 2013 Neil Harris, Michal Filus, Matt Ashfold, Alistair Manning and John Pyle Boulder, Oct 2013 Thanks to WAS team

2. Goals 1.Designing science flights whose measurements can be jointly used to study the transport of trace gases in convection (inflow and outflow). 2.Use ATTREX 2013 as a trial run. 2.Analyse tracer measurements from ATTREX 2013, esp. WAS. Joint flight plans - Jan-Feb 2014

3. Target area Source coordinates Source altitude /km Source dimensions / deg.deg.km Density / particles/layer NAME runs /day Met Office forecast days 1. EAST PACIFIC GH 10 o S-30 o N 130-170 o W 14-16 16-18 40 x 40 x 2 (2)80,00012 back1, 2, 3, 4, 5 2. SOUTH PACIFIC '146' 20 o S-10 o N 160 o E-170 o W 0-530 x 30 x 5225,000 2-5 forward 0, 1, 2, 3 3. WEST PACIFIC '146' 5 o S-25 o N 130-160 o E 0-530 x 30 x 5225,000 2-5 forward 0, 1, 2, 3 Linking GH and ‘146’

4. Data representation: – Distribution studies: fractions crossed 5km – Air history maps – *Altitude vs time plots: qualitative assessment of air mass convection – *Meteorological maps showing weather conditions – Density of particles below 5 km. 12 day back trajectories run using forecast and analysis data. Back- traj started in solid boxes Linking GH and 146 15%51% 10%12%

5. Met Office forecasts and analyses NAME traj dispersion 12 days back Start at 14-16 km in East Pacific Run daily Fraction of air at 14-16 km coming from BL 25 Jan – 29 Mar 2013 Variation over time Consistency between forecasts Linking GH and 146

6. GH East Pacific NAME runs: altitude changes 25 60 SW box above 16 km SW box 14-16 km

7. WAS CHBr3 - 2013 16 > z > 14 km Z > 16 km Mean of easterly values

8. WAS CHBr3 - 2013 16 > z > 14 km Z > 16 km LZRH mean (WMO, 2011) Upper TTL mean (WMO, 2011) Tropical tropop (WMO, 2011) Mean of easterly values Excess caused by recent convection?

9. Simple model: Two sources of air: TTL and inflow region Depends on Time since boundary layer Fraction from in boundary layer Can make more complicated assumptions about trajectories which did not enter low troposphere (in-mixing) [T] MBL = ~2 ppt for CHBr 3 = 0.2 ppt for CHBr 3 [T] TTL 100%0% Fraction of air from MBL [T] MBL [T] TTL Ongoing analysis of WAS CHBr3 - 2013

10. Tracer analysis: Density distribution over the boxes Calculate concentrations of tracers based on WMO climatology and fixed half-life Compare modelled results with ATTREX measurements What resolution is feasible? Back trajectories from Feb 26 2013 which cross 5 km (left) & 1 km (right) Ongoing analysis of WAS CHBr3 - 2013

11. Met Office forecasts and analyses NAME traj dispersion 12 days back Start at 14-16 km in East Pacific Run daily Fraction of air at 14-16 km coming from BL 25 Jan – 29 Mar 2013 Variation over time Consistency between forecasts Variability – select dates, areas

12. Forward calculations from West Pacific below 5 km Met Office forecasts NAME traj dispersion +5 days ahead Start in region of 146 Run daily Anticyclone clear Much in range of GV Based on Ashfold et al., 2012 > 13 km > 10 km

13. Met Office forecasts NAME traj dispersion +5 days ahead Start in region of 146 Run daily Variation over time Fraction of air in BL reaching 10 km 1 Jan – 31 Mar 2013 0 0.3 Forward calculations from West Pacific below 5 km

14. Consider 4 regions

15. Forward calculations from West Pacific below 5 km Variability in all Within 5 days of forecasts, most which have got up there are still within 20°

16. Forward calculations from West Pacific below 5 km 16 km 13 km 10 km 0.02 0.14 0.30 Less transport to higher altitudes More geographic spread if it gets there Implication for flight planning: also need 12 day back-trajectories

18. Thank you

19. Surface and sonde measurements Certainly use trajectories – others?