Programa FAPESP de mudanças globais – 28/Agosto/2008
Efeitos das partículas de aerossóis
no sistema climático
Paulo Artaxo
Instituto de Física, Universidade de São Paulo
[email protected]
Processos físicos e químicos que
regulam a composição da atmosfera
Efeitos climáticos de partículas de aerossóis
I) Efeitos diretos (i.e., não envolvendo nuvens)
a) Reflexão de radiação solar ao espaço
 aumenta o albedo  resfriamento
II) Efeitos indiretos dos aerossóis
• Cada gota de nuvem precisa de um núcleo de condensação
(CCN) para ser formada
• Para uma dada nuvem, mais CCN mais gotículas de nuvens
• Como a quantidade de água é limitada, isso significa
menores gotas de nuvens
IIc) Efeito dos aerossóis na termodinâmica atmosférica e na
dinâmica da convecção. Nuvens rasas com gotículas
líquidas trocadas por nuvens altas com gelo.
Nuvens e Chuva são feitos de 3 ingredientes básicos:
vapor de água
Partícula de aerossol que
age como núcleo de
condensação de nuvens
Condições
termodinâmicas da
atmosfera
Processos altamente não lineares e complexos…
Forçantes radiativas do sistema climático global
Estimates of the aerosol direct radiative forcing
by 20 models at 4AR IPCC 2007
Best estimate: -0.5 W/m2
Range: -0.9 to -0.1 W/m2
Estimates of the Cloud Albedo radiative forcing
due to aerosols from different models
Best estimate:
-0.7 W/m2
Range:
-1.8 to -0.3 W/m2
Forçante radiativa da combinação de todos
os efeitos antropogênicos
O que será feito a esta componente é critico à forçante final
IPCC 2007
Temperature change simulated by a climate model for the
period 1850–2100 with strong or weak aerosol effect
Andreae et al., Nature (2005)
Balanço de radiação terrestre
Aerosol global distribution
Aerosol optical depth (0.44 m)
AERONET and Hadley model
Winter
Summer
The Large Scale Biosphere Atmosphere
Experiment in Amazonia - LBA
Water
(in clouds and biosphere)
Aerosols
(and trace gases)
Anthropogenic activities
Nutrients
(P, N, K, others)
Carbon
Nitrogen
(Vegetation and soil)
Natural biogenic aerosol particles
EPMA photos from Gunther Helas, MPIC
Produção natural de CCN na Amazônia
Isoprene
2-methilthertiol
(From Clayes et al., Science 2004)
Fungal hyphae
1)
2)
3)
4)
Primary biogenic particles acting as Giant CCN
Secondary organic aerosol from terpenes, isoprene, and others
Soil dust (very little)
Sulfates and nitrates (low contribution)
Amazonia in the aerosol world
Andreae et al., 2008
Medidas de longo prazo de aerossóis na Amazônia
Melina Paixao
Fogo e queimadas
Razões para o desmatamento
Deforestation in Amazonia 1977-2008 in km² per year
Deforestation (km² per year)
35000
30000
25000
20000
15000
10000
5000
* média annual da década
Dados do INPE, 2008
07/08
06/07
05/06
04/05
03/04
02/03
01/02
00/01
99/00
98/99
97/98
96/97
95/96
94/95
92/94
91/92
90/91
89/90
88/89
77/88*
0
The most important air pollution issue in
South America is associated to the
continental scale biomass burning during
the dry season. With several hundred of
thousands of fires each year …
•Severe health effects on the population
•Climate effects
•Weather effects
Large scale aerosol
distribution:
strong effects on the direct
radiation balance and cloud
formation
Regional haze
problem is
increasing
around the
globe
Haze over
Ganges Brahmaputra
plain
Beijing
China
Absorção e espalhamento de radiação por aerossóis de queimadas
Scattering (Cooling)
Absorption
(Atmospheric Warming)
Absorption
(Column
Warming)
Cloud Evaporation
(Warming)
Cloud Seeding
(Cooling)
Suppression of Rain;
increase of life time ….
Cooling;
Dimming of Surface
Surface Cooling
Vertical redistribution
of latent and radiative
heating
Aerosol surface forcing in Rondonia 1999-2002
1999-2002 AEROSOL SURFACE FORCING - Rondonia
-400
3.6
AEROSOL FORCING
3.1
AOT
-300
2.1
-200
1.6
-150
aot (500 nm)
2.6
-250
1.1
-100
0.6
0
0.1
Ja
n99
11
-A
pr
-9
9
20
-J
ul
-9
9
28
-O
ct
-9
9
5Fe
b00
15
-M
ay
-0
0
23
-A
ug
-0
0
1De
c00
11
-M
ar
-0
1
19
-J
un
-0
1
27
-S
ep
-0
1
5Ja
n02
15
-A
pr
-0
2
24
-J
ul
-0
2
1No
v02
-50
1-
Radiative forcing (W/m2)
-350
Aline Procópio, GRL 2006
Amazonia
INDOEX
Average aerosol forcing clear sky
average aerosol forcing clear sky
Top: - 10 w/m²
Top: - 7 1 w/m²
Atmosphere: + 28 w/m²
Atmosphere: + 16 2 w/m²
Surface: - 38 w/m²
Surface: - 23 2 w/m²
Conditions: surface: forest vegetation
AOT ( =0.95 at 500nm); 24 hour average
7 years (93-95, 99-02 dry season Aug-Oct)
Procópio et al. (2005)
Conditions: surface: ocean
AOT ( =0.3 at 630 nm); 24 hour average
Jan-Mar 99
Aerosol Optical Thickness
550 nm
Continental scale effects
Solar Radiation
at surface (W m-2)
Karla Longo and Saulo Freitas (INPE)
Aerosol effects on
the Net Plant Productivity
CO2 Concentration
Aerosol Concentration
-
+
+
+
Temperature
+
+
Photosynthesis
Kulmala et al., 2004
+?
BVOC emissions
Efeitos significativos de aerossóis na
produtividade primária da floresta amazônica
Forest site, year: 2000-2001
Solar zenith angle:10-30 degrees
-2 -1
NEE (µmolm s )
0
Dry Season - NEE increase: 46 %
Wet Season - NEE increase: 24 %
-10
-20
-30
 Aumento de aerossóis 
0.0
0.2
0.4
0.6
0.8
Relative Irradiance
1.0
Potential annual forest Net Ecosystem
Exchange (NEE) in the Amazon region
Malhi & Kruijt
Aerosol-cloud-precipitation feedbacks
AEROSOLS
CCN Activation
Cloud/Aerosol
Radiative
Transfer
Cloud Dynamics
Ice Nuclei Activation
Cloud Microphysics
PRECIPITATION
Aerosol Wet
Removal
Crystal shattering
*
*
Aerosol
particles, cloud
condensation
nuclei and
precipitation
Crystal
collection
Evaporation
* *
* *
Collection
Coalescence
Diffusion
SO2
SO4-
Nucleation
Aerosols
Soluble: Nitrates, DON, NH3, NH4+ , etc…
Hydrological cycle critical for Amazonia.
Variety of cloud structure caused
by different CCN amounts and
other cloud dynamic issues
Pyrocumulus Clouds
“Green Ocean Clouds“
Addition of
pyrogenic
CCN has
pronounced
impact on
cloud droplet
size spectra
Four aerosol regimes of:
(A) Blue Ocean,(B) Green Ocean,
(C) Smoky clouds, (D) Pyro-clouds
Note that the narrowing of CDSD and
the slowing of its rate of broadening
with height for the progressively more
aerosol rich regimes from A to D.
Andreae et al., 2005
Large scale low cloud
suppression by biomass
burning aerosols
Terra and Aqua satellite images
of the east Amazon basin, 11
August 2002. (A) The clouds
(Terra, 10:00 local time) are
beginning to form. (B) The
clouds (Aqua, 13:00 local time)
are fully developed and cover
the whole Amazon forest
except for the smoke area. The
boundary between forest and
Cerrado region is marked in
white on both images, and the
seashore is marked in green.
(From Ilan et al., Science
March 2004)
Suppression of low cloud formation by aerosols in Amazonia
. (from Koren and Kaufman, 2003)
Cloud fraction as function of aerosol optical depth (OD). The cloud fraction decreases almost linearly with increasing OD. The red
and blue curves denote the average of east and west areas, respectively. On average, the cloud fraction decreases to less than
1/8 of the cloud fraction in clean conditions when OD = 1. The shaded area represents the relative area covered by the respective
OD, with the integral of this curve equal to one, representing the total Amazon basin
Relationships between cloud properties and aerosol loading in Amazonia
Left – cloud top
pressure (P) vs.
AOD. Lower P may
indicate taller
convective clouds
that reach to
higher levels of the
atmosphere.
Right – cloud
fraction vs. AOD.
The upper row is
for all data and the
lower row is for
data restricted to
cloud fraction less
than half.
Cloud fraction <50%
absorption effects
Microphysics
Ilan Koren et al., Science 2008
Dependence of CCN activation on organic mass fraction
Sulfur at a
level of
30-60 ng/m³)
AMAZE data from Artaxo, Sachin Gunthe, Scot Martin and Qi Chen
Deforestation increase or decrease precipitation?
It depends on the scale.
Precipitation formation
High aerosol
Low aerosol
The effect of aerosol particles in the
vertical profile of cloud droplets size,
phase, and precipitation
Nature, 2008
Predicted change in the probability of a 2005-like drought in Amazonia, based on results from the
HadCM3LC GCM run with aerosols. a, probability versus year; b, probability versus simulated CO2
concentration. Simulations for the twenty-first century show a strong tendency for the SST
conditions associated with the 2005 drought to become much more common, owing to continuing
reductions in reflective aerosol pollution in the northern hemisphere.
São Paulo – 06 de setembro de 2004
Campo Grande – 15 de setembro de 2004
São Paulo – 15 de setembro de 2004
Efeitos radiativos dos aerossóis
em São Paulo
Obrigado pela atenção !!!
Relationships between cloud properties and aerosol loading in Amazonia
Conceptual model of microphysics (MP) and absorption effects on cloud
fraction for 3 saturation/initial cloud fractions Cf0.
Ilan Koren et al., Science 2008