BAHC-sun%20set...

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BAHC-sun set...

• Synthesis volume currently in print ready
  October 2003
• Synthesis Papers, Science series by the end of
  2003
• Last SSC meeting (jointly with ISLSCP/GEWEX in
  September 02(China)
• IPO BAHC was funded until end 2002

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BAHC sun set.

• Sun-set clause and IGBP transition taken
  seriously(?!), no compromising scenarios for
  prolonged life duration
• BAHC community contributing to 3 elements of the
  transition process (I) Water Project, (II)
  Land-Atmosphere Project, and Land Project

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Land - Atmosphere ProjectiLEAPS

• off-spring of BAHC, IGAC, GCTE, GAIM
• full and pro-active partnership with WCRP, story
  of a truly complementary approach
• learning from the past, capitalizing on successes
  of this collaboration (GEWEX-BAHC, LBA, ...)
• stepping stone for future joint programmes
  (mainly with WCRP GEWEX)

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ILEAPSIntegrated Land Ecosystem Atmosphere
Processes
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ILEAPSIntegrated Land Ecosystem Atmosphere
Processes

• Goals
• How do interacting physical, chemical and
  biological processes transport and transform
  energy and materials through the land-atmosphere
  system?
• What are the implications for the dynamics of the
  Earth System?
• How are human activities influencing the
  land-atmosphere system (and vice versa)?
• To what extent does the vegetation optimize its
  physical and chemical environment on various
  temporal and spatial scales?

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NO-NO2-O3-VOC canopy transfer
? NO emitted from the forest soil has to pass the
trunk space and the canopy layer before being
released into the above-canopy atmospheric
boundary layer ? within the canopy, NO can react
with O3 to form NO2, which could be deposited
on/into vegetation elements ? this internal
cycling reduces the NO and net NOx emission from
the forest ecoysystem
Meixner et al., First LBA Scientific Conference,
Belém/Pará, Brazil, 28-JUN-00
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What do land vegetation fires emit?

• CO2
• (climatically relevant only when there is no
  regrowth - e.g., deforestation)
• NOx, CO, CH4, other hydrocarbons
• Ingredients of smog chemistry, greenhouse gases
• Halogenated hydrocarbons (e.g. CH3Br)
• stratospheric ozone chemistry
• Aerosols
• light scattering and absorbing, cloud
  condensation nuclei

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Biota, Aerosols, Clouds, and Climate

• Biosphere/climate feedback proposed in 1987, in
  which marine phytoplankton emits a volatile
  sulfur-containing substance (DMS)
• DMS oxidized to sulfate aerosol particles that
  serve as cloud condensation nuclei (CCN)
• Increased CCN -gtmore cloud droplets -gt clouds
  brighter -gtreduced amount of sunlight absorbed by
  the Earth
• Earth cooling -gt changing the living conditions
  for plankton, and thus their rate of DMS emissions

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Biota, Aerosols, Clouds, and Climate

• feedback thought to be relevant mostly to the
  oceans, continental regions considered always to
  have high levels of CCN, so that clouds would
  never be CCN-starved and any additional CCN
  would have little effect
• recent work in the Amazon shows this assumption
  to be wrong in the wet season with no
  detectable anthropogenic input, the balance of
  natural sources and sinks produces a CCN number
  concentration almost identical to marine values.

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Aerosol - Clouds - Climate Interactions

• More, smaller droplets reflect more light
  climate gets cooler
• When the drops are smaller than a certain size,
  they cannot coagulate to rain drops,
  precipitation is impossible, unless...

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• . There is enough energy (e.g., in the tropics)
  to move rain formation up higher, and involve ice
  formation
• This results in
• more intensive convection
• increased lightning activity (more NOx)
• energy and mass transfer to higher altitudes
• changes in the large scale circulation of the
  atmosphere less rain in West Africa, enhanced
  storm activity in Europe...

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• This rain-suppression applies only to "warm"
  clouds (those not containing ice)
• If there is enough latent heat available
  (tropics) the air will rise and rain-production
  mechanisms involving ice will take over.
• The result is a shift in the energy-release from
  lower levels (warm clouds) to upper levels in the
  troposphere.
• Since the tropics are the heat-engines of the
  atmosphere, this has far-reaching climatic
  effects!

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ILEAPSIntegrated Land Ecosystem Atmosphere
Processes

• Focus 1
• Land-atmosphere exchange of carbon and its
  feedbacks within the Earth System
• CO2
• Methane
• Non-methane VOC

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ILEAPSIntegrated Land Ecosystem Atmosphere
Processes

• Focus 1 Land-atmosphere exchange of reactive
  carbon and its feedbacks within the Earth System
• Issues
• CO2 fluxes at interlinked scales
• Control of interannual variation of CH4 fluxes
• Relationship of VOC fluxes to carbon exchange and
  Net Biome Production
• Feedbacks hydrology/aerosols/VOC
• Self-regulation of VOC fluxes
• In-canopy processes

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ILEAPS
Focus 2 Feedbacks between land biota, aerosols,
atmospheric composition and climate
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ILEAPS
Focus 2 Perturbations by human activities
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ILEAPSIntegrated Land Ecosystem Atmosphere
Processes

• Focus 2A Interactions and feedbacks between
  biogenic/ anthropogenic aerosol production, cloud
  processes, climate and the water cycle
• Issues
• What controls natural CCN abundance?
• How do changes in CCN affect the cycles of water,
  energy, and chemical species
• What are the chemical/microphysical effect of
  carbonaceous aerosols?
• Dust aerosols cloud effects, anthropogenic
  perturbation
• Role of aerosol absorption in climate change
• Representation of above processes in climate
  models

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ILEAPSIntegrated Land Ecosystem Atmosphere
Processes

• Focus 2B Role of the biosphere in the
  self-cleansing mechanisms of the atmosphere
• Role of terrestrial biosphere in self-cleaning
  (NOx, VOC, )
• Effects of global change (land-use, climate) on
  biospheric inputs to self-cleaning
• Effects of changing self-cleaning on biosphere
  (e.g., via oxidants, UV, )

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ILEAPS
Focus 3 Feedbacks and teleconnections in the
land surface -vegetation - water - atmosphere
system

• Effects of land-use and vegetation dynamics on
  climate and hydrology
• Interactions of soil moisture with energy and
  water flux
• Are there multiple stable states, and what are
  the thresholds between them?
• Relative importance of human-induced changes
  (land-use, greenhouse gases, aerosols) on climate
• Effects of changing radiation fields

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Bio-geophysical feedbacks Energy Balance Link
R n LE H S
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Atmosphere - Biosphere Coupling Principles
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ILEAPSIntegrated Land Ecosystem Atmosphere
Processes
Focus 4 Land/Atmosphere Exchange - Theory and
Tools
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ILEAPSIntegrated Land Ecosystem Atmosphere
Processes
Focus 4 Land/Atmosphere Exchange - Theory and
Tools Night-time and stably-stratified flows
Vegetation canopies and complex terrain
Diurnal patterns and low frequency motions Dry
deposition
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ILEAPSIntegrated Land Ecosystem Atmosphere
Processes

• Implementation Strategies
• Integrated (LBA-type studies)
• Integration of results into regional and global
  models
• Long-term measurements (FLUXNET, ...)
• Development of scaling techniques
• Possible bridging areas/projects (LAND, ILEAPS,
  SOLAS, IGAC, )
• FLUXNET, BATREX, alikes..
• Integrated studies hot-spots such as
  mega-cities, costal
• Ecosystem response to BGC-feedbacks in L-A system
• (regional) coupled atmospheric-bgc models