Aerosol effect on cloud cover and cloud height
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Cloud top pressure. What does it mean to climate? The aerosol forcing corresponding to the ... the correlation of aerosol AOT and properties to cloud cover & height ...

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Aerosol effect on cloud cover and cloud height

Kaufman, Koren, Remer, Rosenfeld & Martins


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  • Koren, I., Y. J. Kaufman L. A. Remer and J.V. Martins, Measurement of the effect of Amazon smoke on inhibition of cloud formation, Science, 303, 1342-1344, 2004. http://climate.gsfc.nasa.gov/publications/fulltext/Koren_et_al._(2004).pdf

  • Kaufman, Y. J., I. Koren, L. A. Remer, D. Rosenfeld and Y. Rudich, The effect of smoke, dust, and pollution aerosol on shallow cloud development over the Atlantic Ocean, Proc. Nat. Acad. Scie., 102, 11207-11212, 2005http://climate.gsfc.nasa.gov/publications/fulltext/PNAS-shallow_clouds.pdf

  • Koren, I. Y. J. Kaufman, L. A. Remer, D. Rosenfeld and Y. RudichAerosol impact on the development and coverage of Convective clouds, Geoph. Res. Lett. 32 (14): Art. No. L14828 JUL 30 2005 http://climate.gsfc.nasa.gov/publications/fulltext/2005GL023187.pdf


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1. Smoke inhibition of cloud formation over the Amazon Measurement of the effect of Amazon smoke on inhibition of cloud formation,


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Koren et al Science, 2004; Measurement of the effect of Amazon smoke on inhibition of cloud formation,

Cloud fraction as function of aerosol optical depth (OD). The cloud fraction decreases almost linearly with increasing OD.


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Clouds only Measurement of the effect of Amazon smoke on inhibition of cloud formation,

+8w/m2

-28w/m2

Smoke only

Impacts:

• smoke instantaneous forcing -28w/m2 --> +8w/m2

• smoke 24hrs forcing -11w/m2 --> -5w/m2

• less radiation at the surface => less evaporation

• smaller boundary layer cloud fraction


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2. Measurement of the effect of Amazon smoke on inhibition of cloud formation, Aerosol effects on cloud cover - shallow clouds

The Atlantic Ocean - several aerosol types interacting with clouds June-Aug 2002

Pollution zone

Dust zone

Smoke zone

Marine aerosol

pollution

dust

smoke

Sea salt

convective

convective

stratiform


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Dust Measurement of the effect of Amazon smoke on inhibition of cloud formation,

Stratus and trade cumulus

Clouds

Smoke


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3. Measurement of the effect of Amazon smoke on inhibition of cloud formation, Convective Clouds


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clean Measurement of the effect of Amazon smoke on inhibition of cloud formation,

hazy

Cloud fraction

Cloud fraction

clean

hazy

Cloud top pressure

Cloud top pressure


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What does it mean to climate? Measurement of the effect of Amazon smoke on inhibition of cloud formation,

The aerosol forcing corresponding to the increase in cloud cover is ~ 6w/m2 in the June-Aug period over the Atlantic Ocean

We see similar increases in other locations, depending on the aerosol content of black carbon.

How does it reconcile with global warming?


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x. What is the response of the cloud water path to 50 yr increase in aerosol concentration?

A. Fixed ocean temperature

B. feedback through ocean temperature

Takemura, Kaufman, Remer, Nakajima, submitted


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“The aerosol roadmap” increase in aerosol concentration?


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Aerosol effect on cloud cover and cloud height increase in aerosol concentration?

• MODIS is in unique position to measure the correlation of aerosol AOT and properties to cloud cover & height

• We find increases in cloud cover on average of 0.05 → ~ 6 W/m2

• We find an average increase in cloud height of ~ 400 m (-40 mb)

• Model shows that long term aerosol cooling of the ocean may compensate the aerosol effect on cloud cover through impact on cloud microphysics


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