Biosphere/Atmosphere Interactions in the Tropics
NO emission from soil
VOC emitted from leaf surface
O3 deposition to leaf surface
O3 and NO2 deposition to
stomata
NO + O3 NO2 + O3
NO + O3 NO2 + O2
NO2 + O2 NO + O3
RO’2 + NO RO’ + NO2
NO, NO2, O3, VOC
hv
VOC NO
NO2
NO2
NO2
NO
O3
O3
Modified after Coe et al. 1993
HNO3NH3
HONO?
OH and the Amazon,an untested hypothesis
Some Questions
• What are the timescales of transport and chemical processes in nitrogen cycling between ecosystems and atmosphere?
• How do they interact to determine N species flux in and out the ecosystems?
• How does ecosystem exchange on VOC and N species affect the atmospheric oxidant cycle?
CCN sources in the “clean” tropics:
• Dust, Sea Spray: Over the humid continental tropics, too few to be important
• Marine biogenic sulfate (from DMS): Probably important some of the time
• Terrestrial biogenic sulfate (from DMS and H2S): May play a key role in providing soluble aerosol component
• Secondary Organic Aerosol: May provide a significant part of aerosol mass, but mode of particle formation still under question
• Primary biogenic aerosol: Bacteria, spores, plant debris may account for a large fraction of aerosol mass and number!
CCN Efficiency Spectra
0.0
0.2
0.4
0.6
0.8
1.0
0.0 0.5 1.0 1.5
Supersaturation, %
CC
N E
ffici
ency
as
CC
N/C
N r
atio
Aged Smoke in Cloud Layer
Fresh Smoke in Mixed Layer
Green Ocean (CLAIRE98)
Pyrogenic CCN have
pronounced impact on
cloud droplet size spectra!
Aerosol pollution increases the height where cloud drops grow big enough to grow by coagulation and form “warm” rain
(Andreae et al., SCIENCE, 2004)
Some Questions
• What is the source of “background” Amazonian aerosols, and what are their properties?
• What determines the cloud droplet and ice nucleating ability of Amazonian aerosols?
• How do aerosols affect the formation and properties of ice phase in clouds over Amazonia?
• How do aerosols affect rainfall amount and rain rate over Amazonia?
Compare flash rates in January...
… and in September
How does smoke get into the stratosphere??
Simulation of a Pyrocumulus Blowup
Potential Temperature on the 100 µg/m³ aerosol-isosurface
Some Questions
• Do aerosols affect the amount and distribution of lightning over Amazonia?
• Does this affect the chemical properties of the atmosphere?
• Do fires and aerosols affect the intensity of deep convection in the tropics?
• Is this important for the chemistry and physical properties of the UTLS?