Mark G. Lawrence Max Planck Institute for Chemistry, Mainz, Germany

1. Cloud Processing of Trace Gases and Aerosols: What are we missing / what should we do in the future? Mark G. Lawrence Max Planck Institute for Chemistry, Mainz, Germany Chemistry-Climate Interactions Workshop Santa Fe, 10 February 2003

2. “At the Cleaners with Mark” Mark G. Lawrence Max Planck Institute for Chemistry, Mainz, Germany Chemistry-Climate Interactions Workshop Santa Fe, 10 February 2003

3. “Doing the Laundry with Mark” Mark G. Lawrence Max Planck Institute for Chemistry, Mainz, Germany Chemistry-Climate Interactions Workshop Santa Fe, 10 February 2003

4. Objectives • Importance of clouds for atmospheric chemistry? • Major outstanding issues? • (Chemistry  climate?) • Organized Picture of the wide range and complexity of issues

5. Topics Break down into 2x2 different topics: • Cloud type • Shallow: • Stratiform, fair weather cumulus, and non-Cb cirrus • Deep: • Vertical motions exceeding 2-3 km:Cumulus convection (cu-congestus to MCSs and Hurricanes) and deep cirrus anvils (e.g., squall line) • Chemical phase • Gases • Aerosols

6. Outline • Shallow Clouds • Introduction/Effects • Issues • Deep Clouds • Introduction/Effects • Issues • Assessment of Priorities  Illustrations/Examples largely with MATCH results • Current studies often not explicitly listed

7. ISSUE Importance (O3, AOT) Difficulty (80-90% job) G A G A SHALLOW CLOUDS Parameterization: Microphysics Parameterization: Cloud Fraction Liquid water chemistry: Role of internal/external mix Liquid water chemistry: Uptake kinetics/amount … DEEP CLOUDS Parameterization: Thermo/Location/Intensity Vertical Transport: Entrainment Vertical Transport: Detrainment Vertical Transport: Downdrafts … Fill in with L/M/H Fill in with L/M/H

8. Shallow Clouds

9. Stratocumulus North Atlantic (From the Karlsruher Wolkenatlas)

10. Stratocumulus Germany (From the Karlsruher Wolkenatlas)

11. Fair Weather Cumulus Karlsruhe (From the Karlsruher Wolkenatlas)

12. Altocumulus Lenticularis Utah Processing air (From the Karlsruher Wolkenatlas)

13. Cirrus New Mexico New Mexico Bolivia (From the Karlsruher Wolkenatlas)

14. Shallow Cloud Issues • Parameterization • Liquid Water Chemistry • Ice Surface Chemistry • Precipitation Scavenging • Radiative Transfer / Photolysis Rates

15. Control Large-Scale Processes Cloud-Scale Processes Feedback Issues: Parameterization • Microphysics • Currently mainly bulk schemes • Global models: mostly prognostic only for total condensate, diagnostic for the rest • Cloud resolving models: typically bulk schemes but prognostic for all condensate types

16. Control Large-Scale Processes Cloud-Scale Processes Feedback Issues: Parameterization • Cloud cover • Diagnostic threshold (Slingo) schemes in widest use • Often decoupled from microphysics, though recent improvements…? • Always decoupled from advection (so far…)

17. Issues: Parameterization • Cloud cover – resolving cloud systems <2% of rain cells (and <5% of clouds) exceed T42 (~105 km2), however… From Wilcox, Thesis, 2002

18. Issues: Parameterization • Cloud cover – resolving cloud systems No coupling of clouds in one grid cell with those in the neighboring cells! …rain cells > T42 produce 70% of the total precipitation Houze/Mapes (Pacific): 1% of clouds > 105 km2, but are 25% of total cloud cover From Wilcox, Thesis, 2002

19. Issues: Liquid Water Chemistry • Aerosols • Crucial for processing of all aerosol types • Importance of internal/external mixtures (type, age, and size) and coating for determining hygroscopicity, nucleation, and optics? • Collection/uptake of existing aerosols by droplets? • Form of aerosols after evaporation (and evaporation process)? • Coupling with gas phase chem (e.g., interaction of S and N cycles, halogen release, etc.)?

20. Issues: Liquid Water Chemistry • Gases • Effects on O3 and HOx still under debate: locally strong, globally moderate to weak • Halogen and NMVOC reactions? • Coupling with aerosol chem (e.g., SO2 oxidation, N2O5 hydrolysis)?

21. Issues: Ice Surface Chemistry • Aerosols • Uptake/ageing of aerosols on ice? Dependence on type/mixture? • Gases • Halogen activation? • HO2 + O3 (and other O3- or HOx-related reactions?) • NMVOC reactions?

22. Issues: Precipitation Scavenging • Aerosols • Major loss for all aerosol types (some after processing) • Importance of aerosol type/mixture for nucleation and collection?

23. Issues: Precipitation Scavenging • Gases • Major loss process for reactive nitrogen, odd hydrogen, VOCs, and halogens • Water solubilities generally known (except VOCs) • Ice uptake/retention very poorly characterized • Kinetic uptake limitations difficult to model (generally neglected)

24. Issues: Precipitation Scavenging • Example: Effect on soluble gases with a surface source Hx in M/atm: Hx= 0 Hx = 103 Hx = 104 Hx = 105 Hx = 106 Based on Crutzen and Lawrence, J. Atmos. Chem., 2000

25. Issues: Precipitation Scavenging • Example: Effect on soluble gases with a surface source Hx in M/atm: Hx= 103 Hx = 104 Hx = 105 Hx = 106 Hx = 1010 Based on Crutzen and Lawrence, J. Atmos. Chem., 2000

26. Issues: Precipitation Scavenging • General • Precipitating fraction and stratiform/convective split • Preservation of information on scavenged areas • Slower sedimentation of smaller hydrometeors

27. Issues: Precipitation Scavenging • Precipitating fraction From Wilcox, Thesis, 2002

28. Issues: Precipitation Scavenging • Preservation of Information / Artificial Mixing t0 t0 + scav+ adv t0 + scav t0 + t Shorter t => worse artificial mixing!

29. Issues: Precipitation Scavenging • Slower sedimentation of smaller hydrometeors From Lawrence and Crutzen, Tellus, 2000

30. Issues: Radiative Transfer • Effects on Photolysis Rates (and heating rates…) • Effect on OH and CH4 small to moderate (~10%) • Already simulated rather accurately (Landgraf/Crutzen) MATCH-MPIC simulation From Landgraf, Thesis, 1998

31. Deep Clouds

32. Organized Convection

33. Cumulus Congestus Miami Near Karlsruhe Karlsruhe (From the Karlsruher Wolkenatlas)

34. Cumulonimbus with and without Anvil (From the NOAA Gallery)

35. Supercell Cumulonimbus (From Houze‘s Cloud Atlas)

36. Squall Line

37. Hurricane Floyd

38. Deep Convection: Characteristics Mass-Balance Subsidence Updrafts Downdrafts

39. Eigenschaften der Konvektion Deep Convection: Characteristics Anvils (Ice) Lightning Precipitation and slower Sedimentation Precipitation

40. Deep Cloud Issues • Parameterization • Vertical (dry) Transport • Precipitation Scavenging • Lightning NOx

41. Control Large-Scale Processes Moist-Convective Processes Feedback Issues: Parameterization • Severalcomponents to deal with: • Thermodynamics (T/t, Q/t, Q1, Q2) • Microphysics • Cloud Cover / Precipitation Swath • Mass Fluxes / Tracer Transport • Proper treatment in offline models (pre-stabilized thermodynamic profiles)

42. Control Large-Scale Processes Moist-Convective Processes Feedback Issues: Parameterization • Wide range of philosophies and closures • Focus of testing on thermodynamics;  Tracers (e.g., CO, CH3I) may provide powerful tests • Mesoscale organization rarely considered • CEMs: delays in response to large-scale forcing • First attempts by Donner, others? • Relevance for tracer transport unknown, likely substantial

43. Issues: Vertical (dry) Transport • Updraft Effects – Transport to the UT: • O3 and O3-precursors • HOx reservoirs • Stratosphere-relevant gases (halogenated gases, COS) • Aerosols – esp. Dust, BC, OC, and Sulfate precursors • Clean air masses Example: Southern Asian CO from MATCH-MPIC

44. Z Mu Issues: Vertical Transport Tropopause ? ? Entrainment into the Ensemble

45. Z Mu Issues: Vertical Transport Tropopause Detrainment from the Ensemble ? ? ? Entrainment into the Ensemble

46. Z Mu Issues: Vertical Transport Tropopause ? Detrainment from the Ensemble ? ? ? ? Entrainment into the Ensemble ?

47. Issues: Vertical Transport • Updraft Effects – Importance of Detrainment Region: MATCH-MPIC O3: Detrain-top ---------- Base run

48. Issues: Vertical Transport • Downdrafts • Strength • Feeder Regions • ( Organization) • Entrainment • Detrainment • Significance of downdrafts? ? ? Put in a Fig here from MATCH Downdraft run!

49. Issues: Vertical Transport • Mass-Balance Subsidence • In same model column? • As part of circ. cells • (Hadley, Walker)?

50. Issues: Vertical Transport • Role of Subsidence, Balance with Updrafts: From Lelieveld and Crutzen, Science, 1994