Baumann, Robert

Cai, Duy Sinh

Eyring, Veronika

Gottschaldt, Klaus-Dirk

Graf, Phoebe

Hoor, P.

Jurkat, Tina

Jöckel, Patrick

Schlager, Hans

Voigt, Christiane

Zahn, Andreas

Ziereis, Helmut

Institute of Transport Research:Publications

Composition and transport  in the Asian summer monsoon anticyclone (ASMA):  A case study based on aircraft observations and model simulations   K. Gottschaldt, H. Schlager, with contributions from R. Baumann, D. S. Cai, V. Eyring, P. Graf, P.  Hoor,  P. Jöckel, T. Jurkat, C. Voigt, A. Zahn, H. Ziereis > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 2 1. HALO ESMVal campaign  2. EMAC simulation & HYSPLIT trajectories 3. Measurements vs simulation 4. Back-trajectories 5. Tracer characteristics in the ASMA 6. Tracer-tracer relations 7. Entrainment at the eastern ASMA flank 8. Splitting and stirring  Outline > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 3   1. HALO ESMVal campaign  EMAC NOy nmol/mol, 140 hPa 23/09/2012,  18 UTC Pollution • 65 HALO flight hours from 10 – 24 September 2012 • in close collaboration with HALO TACTS mission • targeting specific large scale features to gather data for ESM evaluation 18 Sep 2012 > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 4 • CCMI Ref-C1SD setup, EMAC 2.5 (simulation REF-C1SD-base10a, project ESCiMo)      •  T42L90MA resolution: ~150 km grid size, 90 vertical levels to 80 km Comparison to measurements based on highest possible resolution: time series along aircraft flight track, ∆t =12 min (simulation time step) Dynamics nudged towards ECMWF ERA-Interim re-analyses data   2. EMAC simulation and HYSPLIT trajectories   EMAC (ECHAM/MESSy Atmospheric Chemistry model) HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectory model)  • Back-trajectories starting @ flight track • Driven kinematically by GDAS 1°x1°, 23 vertical levels (1000 … 20 hPa) > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 5   3. Measurements vs simulation > O3 km obs downsampled to sim sim obs Sudden increase in ASMA by about 50 nmol/mol (contrasts satellite climatologies,  triggered this study) ~20 nmol/mol offset, but pattern ok > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 6   3. Measurements vs simulation > Other tracers HCl CO NO NOy • @ instrument limit • possibly spurious  washing out or slightly misjudged gradient in sim   Surprisingly good for  monthly BB Lightning parameterized: Can not expect exact match Pattern ok > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 7 • Caution needed in regions with strong gradients / transport barriers  • Consider coarse resolution, approximations / parameterizations in the simulation (incl. initial and boundary conditions)   3. Measurements vs simulation > Summary Surprisingly well reproduces observations of HALO ESMVal, at least large scale features Obs  O3, HCl, CO, NO, NOy enhanced in ASMA filament(s) Sim  Ok to use for interpretation of the measurements   4. Back-trajectories 60°E 75°E 90°E 45°E 30°E 15°E 60°E 75°E 45°E 30°E 15°E 90°E 45°E 60°E 75°E 90°E hPa 150 200 250 300 350 400 450 500 < > Male-Larnaca 2 1 3 3 2 1 All 3 flight segments have seen  a filament of similar genesis:  • At least one ASMA roundtrip in UT  • Entrainment by upwelling at  eastern ASMA flank > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 9   4. Back-trajectories • Eastern ASMA flank passed 15 / 12 / 13 September 2012 • almost parallel streamlines  in southern fringe @ ~const. altitude > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 10   4. Back-trajectories > Summary • Filament transected     outside-in,       outside in,      inside-out  • ASMA moved eastward during the considered period & became smaller  1 3 2 1 3 2 > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 11   5. Tracer characteristics in the ASMA > Synoptic situation 168 hPa > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 12   5. Tracer characteristics in the ASMA > Evolution 2012 hPa TP TP TP EMAC simulation TP 30°S-30°N: WMO  else: 3.5 PVU > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 13   5. Tracer characteristics in the ASMA > Evolution 2012 (sim) • no obvious O3 minimum in ASMA  • HCl stratospheric tracer in ASMA  • CO tropospheric tracer in ASMA; proxy for non-NOx O3 precursors  • E-shaped NOy profile in ASMA  • NOx has UT sources, probably lightning  • NOx/NOy max @ TP, rather constant throughout the year  • Net photochemical O3 production is >0 and has a local max in ASMA UT NOx meeting uplifted other precursors > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 14   6. Tracer-tracer relations > Mixing lines Mixing of two reservoirs,         &        , containing species A &B 21• c1 & c2  const. → slope const  • any component of c1 or c2 different (incl. via inmixing) → different slope   • mixing line exists as long as  mixing continues  • shrinks, if  reservoirs are not replenished • different in-situ  production  changes slope     • non-equal contributions  from reservoirs = non-symmetric shrinking of mixing line • mixing complete = one point in tracer-tracer diagram > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 15   6. Tracer-tracer relations > Mixing lines Mixing of two reservoirs,         &         („end members“), containing species A &B 21• c1 & c2  const. → slope const  • any component of c1 or c2 different (incl. via inmixing) → different slope   • mixing line exists as long as  mixing continues  • shrinks, if  reservoirs are not replenished • different in-situ  production  changes slope     • non-equal contributions  from reservoirs = non-symmetric shrinking of mixing line • mixing complete = one point in tracer-tracer diagram > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 16   6. Tracer-tracer relations > HCl vs O3 • Observations in  tropospheric branch  • HCl ~ stratospheric • CO ~ tropospheric            influence  • HCl ~ O3 for a range of  strat/trop gradients (incl. zero)   • const. O3 likely corresponds to strat/trop gradient  • const. HCl likely corresponds  to gradient of net O3 production Obs show both  scenarios  + intermediates > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 17   6. Tracer-tracer relations > CO vs O3 • Observations in  tropospheric branch • Mixing lines O3 ~ CO likely  originate from reservoirs of  similar HCl, i.e. similar strat. influence  → different ProdO3 - LossO3  • Mixing lines -O3 ~ CO likely to correspond to a gradient of strat./trop. influence • negative slopes  dominate  • Shifted by different ProdO3 - LossO3 ? > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 18   6. Tracer-tracer relations > NO(x) vs O3 O3 / nmol/mol • ambiguous @ intersection of tropospheric and stratosheric branch • Enhanced O3 may either coincide with   enhanced (small) strat.           or enhanced trop. contribution Observations  mostly O3 ~ NO > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 19   6. Tracer-tracer relations > NO(x) vs NOy • TP branch is lower than stratospheric branch or UT region → consistent with local      NOy minimum at TP  • NOy ~ NOx favoured for a range of gradients of  tropospheric influence > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 20   7. Entrainment @ eastern ASMA flank > Zoom in Fringe filament measured outside-in > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 21   7. Entrainment @ eastern ASMA flank > Zoom in Mixing line between  CO↓↑O3 (out)       & CO↑↓O3 (in)  Negative slope:  ~ strat./trop. gradient   Suite of parallel lines NOx ~ NOy Corresponding to different CO   O3 ~ HCl: some strat./trop. Gradient   O3 ~ NO: ? a b c d CO vs O3 NO vs O3 HCl vs O3 NO vs NOy > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 22   7. Entrainment @ eastern ASMA flank > Zoom in Situation  as seen by simulation:  • Measurements originate in gradient between UT air and uwelling  • veering away from TP  • Net ProdO3 max at interface (CO↑ + NO↑): O3 gradient in mixing line not due to ∆ProdO3  • Net Prod O3 rather ~CO than ~NO  • Entrainment from TP region at tropopause trough (may not have contributed to actual measurements) > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 23 2   7. Entrainment @ eastern ASMA flank > Zoom out Simulation:  • Entrainment of stratospheric tracer (incl. TP region) at eastern ASMA flank not a rare event  • mostly associated with TP trough HCl > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 24   7. Entrainment @ eastern ASMA flank > STE 2 • STE hotspot over Eastern Mediterranean may contribute some stratospheric signatures to ASMA  • Event shown here was too early for HALO ESMVal • Note: there is always entrainment of enhanced O3 at eastern flank > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 25   8. Splitting and stirring   > Event @ HALO ESMVal  2 • ASMA splits in response to a 2nd TP trough, moving in from the West  • Redistribution across former transport barriers: Fringe  (~HCl) Interior (~CO) Iranean interior Iranean fringe Tibetan interior Tibetan fringe > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 26   8. Splitting and stirring > @ Different altitudes south ward north ward Wind  fraction 2012 • Red (West) – Blue (East) combination at a point in time is an anticyclone  • Tibetan anticyclone dominates UT  • Iranean anticyclone becomes more important in middle troposphere HALO ESMVal 10–40°N > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 27   8. Splitting and stirring        > 5 seasons 2 • ASMA splitting events occur quite frequently • Tibetan part dominates UT    • Ridgeline latitude varies     • Southern fringe often associated with increased HCl, i.e. TP entrainment  a b c > Vortrag > Autor  •  Dokumentname > Datum www.DLR.de  •  Folie 28 Summary • HALO ESMVal transected ASMA filament 3 times in September 2012: increased O3, CO, HCl, NOy  • mixture of lower tropospheric upwellings and UT ASMA air  • ASMA UT trace gas signatures show entrainment of  stratospheric components, probably from the TP region at eastern ASMA flank  • In-situ net O3 production increased in ASMA, where UT NOx meets lower tropospheric precursors: Certainly contributes to increased O3  • ASMA splitting / Eddy shedding overcomes transport barriers of the intact anticyclone and stirs effectively  • Entrainment at eastern ASMA flank & Eddy shedding sensu lato are common   

Composition and transport in the Asian summer monsoon anticyclone (ASMA): A case study based on aircraft observations and model simulations

Composition and transport in the Asian summer monsoon anticyclone (ASMA): A case study based on aircraft observations and model simulations

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Institute of Transport Research:Publications