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Explore the influence of aerosols on cloud cover and height based on research by Kaufman, Koren, Remer, Rosenfeld, and Martins. Discover the effects of smoke inhibition on cloud formation and the interaction between various aerosol types and clouds over the Atlantic Ocean.
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Aerosol effect on cloud cover and cloud height Kaufman, Koren, Remer, Rosenfeld & Martins
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
Koren et al Science, 2004; Cloud fraction as function of aerosol optical depth (OD). The cloud fraction decreases almost linearly with increasing OD.
Clouds only +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
2. 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
Dust Stratus and trade cumulus Clouds Smoke
clean hazy Cloud fraction Cloud fraction clean hazy Cloud top pressure Cloud top pressure
What does it mean to climate? 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?
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
Aerosol effect on cloud cover and cloud height • 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