A Cloud Physics Facility for DUSEL

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A Cloud Physics Facilityfor DUSEL

• John Helsdon
• South Dakota School of Mines Technology
• Patrick Chuang
• Univ. of California Santa Cruz

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Big Question

• 2001 National Research Council Report
• Examined Key Questions in Climate Science
• 60 of Climate Sensitivity Due to Feedbacks
  Involving
• Water vapor
• CLOUDS
• Conclusion
• Climate Uncertainty Will Remain Until a More
  Fundamental Understanding of Clouds is Achieved

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Clouds and Climate

• Key Component of Climate System. Clouds Affect
• Incoming Sunlight
• Outgoing Longwave IR
• Vertical Transport of Energy, Moisture, Trace
  Gases
• Precipitation in All Forms (Including Cleansing)
• Atmospheric Chemistry
• SO2 oxidation to SO4 in cloud droplets
• Nitrogen fixation by lightning

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Environments for Studying Clouds

• Laboratory Studies
• Well-controlled
• Unrealistic length scales and residence times
• Field Studies
• Realistic conditions
• Poorly-controlled
• Difficult sampling conditions (aircraft)
• Expensive

• Model Studies
• Well-controlled, detailed results
• Need to be tested and validated against
  observations
• Vertical Shaft Studies
• Reasonably well-controlled
• Reasonably realistic length scales and residence
  times
• Easier sampling conditions
• Particles at terminal velocity

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Precipitation Formation

• How Does Precipitation Form in Clouds?
• Initiation of precipitation in warm clouds is a
  longstanding problem in cloud physics
• Ice phase interactions are primary path to
  precipitation, but poorly understood
• Vertical shaft cloud would permit testing of
  central hypotheses, such as the role of aerosol
  distributions, turbulence, electrical effects,
  temperature, etc.

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Aerosol-Cloud Interactions

• What are Properties of Clouds Formed From
  Aerosols Composed of Mixture of Organic and
  Inorganic Compounds?
• Activation behavior of organic aerosols poorly
  understood
• Vertical shaft cloud permits controlled
  experiments with complex aerosol (e.g., biomass
  burning, combustion aerosol) in realistic cloud
  conditions

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Cloud Electrification Studies

• Ice Particle Interactions in Supercooled Cloud
  Environment Thought to Cause Charge Separation up
  to Lightning
• Many types of ice particles in natural cloud
• Interaction coefficients poorly defined
• Vertical shaft cloud with mixed-phase water
  environment and detailed observations will help
  resolve interaction matrix

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Cloud-Turbulence Interactions

• How Does Turbulence Affect the Evolution of Cloud
  Properties?
• Microscale turbulence ( mm to cm length scales)
  hypothesized to affect cloud processes such as
  condensation, collision-coalescence/aggregation,
  radiative transfer, but experimental data lacking
• Vertical shaft cloud exhibits higher Reynolds
  numbers than achieved in laboratory conditions,
  permitting better experimental data to address
  questions

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Cloud Chemistry

• How do Models of Aqueous Phase Chemistry in
  Clouds Compare with Measurements?
• Conversion of S(IV) to S(VI) well known to be
  important for atmospheric chemistry
• Reactions involving other species also believed
  to be significant
• Vertical shaft cloud would provide real cloud
  conditions on timescales sufficiently long to
  study such reactions

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Other Studies

• Cloud Remote Sensing
• Cloud Radiative Transfer
• Instrument Inter-comparison
• Adiabatic Parcel Models
• Multi-Dimensional Simulation Models

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It is Fitting that a Cloud Physics Facility
Should be Associated with a Particle Physics
Facility.One of the Original Particle Physics
Detectors was the Wilson Cloud Chamber.