Motivation Sensitivity of Precipitation to Aerosol Concentration. (Based partly on 2 d results)....

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.

Set-Up

• First set of simulations was done with liquid only microphysical processes.

• Grid spacing was 3 km.

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Perhaps

• We need a source of aerosols to replace those scavenged.

• Simulation redone with constant (source of), continental aerosols.



Scavenging of aerosols leads to lower clouds with warmer cloud top temperatures (but dynamics more important).

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Model Restarted

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





Ice processes

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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.

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

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.

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 (?)

Motivation Sensitivity of Precipitation to Aerosol Concentration. (Based partly on 2 d results)....

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