In Situ Validation of the Suppression of Rain by Smoke from Forest Fires in the Amazon D. Rosenfeld and A. Khain (1), A. A. Costa (2), J. C. P. de Oliveira (3), M.O. Andreae (4), P. Artaxo (5) 1.Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel 2.Universidade Estadual do Ceará, Av. Paranjana, Campus do Itaperi - Fortaleza - CE / CEP , Brazil, 3.Universidade Federal do Ceará, Campus do Pici, Caixa Postal 6030 – Fortaleza-CE / CEP , Brazil 4.Biogeochemistry Department, Max Planck Institute for Chemistry, P.O. Box 3060, D Mainz, Germany 5.Instituto de Fisica, Universidade de Sao Paulo, Rua do Matao, Travessa R, 187, CEP , Sao Paulo, Brazil

VIRS+PR, Amazon, SEP 14:15 VIRS T-Re TOMS Aerosol Index 13 September 1998 Note that clouds do not precipitate before reaching height of 6.5 km or –12 o C isotherm, while containing ample cloud water. The “Green Ocean” turns dry: Smoky clouds over the Amazon

Note the shallow precipitating clouds, extensive warm rainout, glaciation at T>-10 o C, and few lightning TRMM VIRS+PR, Amazon, :28 VIRS T-Re The “Green Ocean”: Maritime clouds over the Amazon

North of Ji Parana, 4 October 2002, 16:03 GMT. Moderate smoke,

MODIS AQUA, 7S-12S, 62W-66W, 4 October 2002, 17:50 GMT.

Near Cruzeiro do Sul, 4 October 2002, 22:10 GMT. Warm Rain, 2.5 km

MODIS AQUA, 5S-10S, 64W-71W, 4 October 2002, 17:50 GMT.

Many more droplets for the same supersaturation Summary of CCN Spectra

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The smoke decreases the rainfall amounts.

The smoke increases the updrafts intensity.

Conclusions 1.The aircraft measurements in clean and smoky clouds, up to the 0 o C isotherm confirm and strengthen the previous satellite inferences of smoke suppressing warm precipitation in convective clouds. 2.Apparently the giant ash CCN are not significant in initiation of warm rain, even in pyro-cumulus. 3.Model simulations replicate the aircraft measurements and extrapolate them to greater heights in the clouds, supporting the observations that smoky clouds have to exceed the -10 o C isotherm level for start precipitating. 4.Simulations show that smoky cumulonimbus produce less precipitation than clean clouds under the same conditions. 5.However, the updrafts velocities in smoky clouds are stronger and supercooled water content is greater, providing better conditions for cloud electrification.

The classification scheme of convective clouds into microphysical zones according to the shape of the temperature – effective radius relations Note that in extremely continental clouds r e at cloud base is very small, the coalescence zone vanishes, mixed phase zone starts at T<-15 o C, and the glaciation can occur at the most extreme situation at the height of homogeneous freezing temperature of –39 o C. In contrast, maritime clouds start with large r e at their base, crossing the precipitation threshold of 14  m short distance above the base. The deep rainout zone is indicative of fully developed warm rain processes in the maritime clouds. The large droplets freeze at relatively high temperatures, resulting in a shallow mixed phase zone and a glaciation temperature reached near –10 o C