Motivation

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Motivation

• Sensitivity of Precipitation to Aerosol
  Concentration. (Based partly on 2 d results).
• Theory Precipitation occurring in a maritime
  airmass should develop sooner and precipitate on
  the upwind slope. Precipitation in continental
  aerosols should be displaced downwind (if it
  develops at all).
• Cloud tops in continental runs should be cooler,
  as slower diffusional growth is favored over
  growth processes occurring through collisions.

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Set-Up

• First set of simulations was done with liquid
  only microphysical processes.
• Grid spacing was 3 km.

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Figure 1
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Figure 2
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Figure 3
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Figure 4
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Figure 5
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Figure 6
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Figure 7
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Figure 8
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Figure 9
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Figure 10
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Figure 11
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Figure 12
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Perhaps

• We need a source of aerosols to replace those
  scavenged.
• Simulation redone with constant (source of),
  continental aerosols.

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Figure 13
Scavenging of aerosols leads to lower clouds with
warmer cloud top temperatures (but dynamics more
important).
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Figure 14
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Figure 15
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Figure 16
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Model Restarted

• Simulations with maritime and continental
  aerosols, starting from the same initial
  conditions at 16 GMT

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Figure 17
Ice processes
Some enhancement of precip.
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Summary Part II

• Initially, deep clouds over a mountainous terrain
  in a maritime environment produce more rain than
  clouds in a continental environment.
• Over time, the clouds in a continental
  environment produce more rain.

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Explanation?

• Scavenging of large aerosols allows continental
  air mass to evolve towards a maritime condition.
• Differences in cloud height support this.
• Yet, even with constant aerosols in a continental
  environment, precipitation from clouds in this
  environment is more than in the
  maritime/continental simulation

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Shallow clouds (should) conform to theory?

• Differences in precipitation from shallow clouds
  developed much the same way as deep clouds (but
  effect was proportionally more important).
• Cloud top heights were cooler in maritime
  simulation than in continental simulation?
• Including ice processes does not change the
  result.
• Real world is more complex than prevailing
  theory and results from 2d simulations.

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Ongoing and Future Work

• Coupling of SBM in WRF (NSF SGER)
• Further investigation of aerosol effects on
  precipitation (PIER, Israeli Science Foundation,
  ANTISTORM)
• Development of hybrid SBM bulk microphysical
  model (?)