1. 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

2. 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

3. Land - Atmosphere Project iLEAPS 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)

4. ILEAPS Integrated Land Ecosystem Atmosphere Processes

5. 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?

6. NO-NO 2 -O 3 -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 O 3 to form NO 2, which could be deposited on/into vegetation elements this internal cycling reduces the NO and net NO x emission from the forest ecoysystem Meixner et al., First LBA Scientific Conference, Belém/Pará, Brazil, 28-JUN-00

8. What do land vegetation & fires emit? CO 2 –(climatically relevant only when there is no regrowth - e.g., deforestation) NO x, CO, CH 4, other hydrocarbons –Ingredients of smog chemistry, greenhouse gases Halogenated hydrocarbons (e.g. CH 3 Br) –stratospheric ozone chemistry Aerosols –light scattering and absorbing, cloud condensation nuclei

9. 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 ->more cloud droplets -> clouds brighter ->reduced amount of sunlight absorbed by the Earth Earth cooling -> changing the living conditions for plankton, and thus their rate of DMS emissions

10. 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.

11. 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...

12. …. 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 NO x ) –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...

13. 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!

16. ILEAPS Integrated Land Ecosystem Atmosphere Processes Focus 1: Land-atmosphere exchange of carbon and its feedbacks within the Earth System  CO 2  Methane  Non-methane VOC

17. ILEAPS Integrated Land Ecosystem Atmosphere Processes Focus 1: Land-atmosphere exchange of reactive carbon and its feedbacks within the Earth System Issues: CO 2 fluxes at interlinked scales Control of interannual variation of CH 4 fluxes Relationship of VOC fluxes to carbon exchange and Net Biome Production Feedbacks hydrology/aerosols/VOC Self-regulation of VOC fluxes In-canopy processes

18. ILEAPS Focus 2: Feedbacks between land biota, aerosols, atmospheric composition and climate

19. ILEAPS Focus 2: Perturbations by human activities

20. ILEAPS Integrated 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

21. ILEAPS Integrated 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 (NO x, 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, …)

22. 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

23. LE = 0.65 R n LE = 0.25 R n H = 0.3 R n H = 0.65 R n Boreal Forest Temperate Forest Bio-geophysical feedbacks: Energy Balance Link R n = LE + H + S 0.10 R g R n = 0.87 R g 0.10 R g R n = 0.87 R g S = 0.03 R n S = 0.07 R n 25 m 10 m PBL 1500 m PBL 3000 m CAPE + cloud activity characteristics

24. Atmosphere - Biosphere Coupling Principles 1 Convective Boundary Layer (CBL) Effects Boundary layer structure, including its depth, is directly influenced by the surface heat and moisture fluxes 2 Local Wind and Mesoscale Circulation Effects Local and mesoscale (wind) circulations can subsequently result from horizontal variations in land surface heat fluxes and the depth of CBL (e.g. sea- and land breezes) Local wind circulation lead to boundary wind convergence, which lead to increased measures of the potential for deep cumulus convection 3 Effects on Convective Available Potential Energy (CAPE) CAPE can considerably increases/decreases in response to surface moisture and surface temperature

25. ILEAPS Integrated Land Ecosystem Atmosphere Processes Focus 4: Land/Atmosphere Exchange - Theory and Tools

26. ILEAPS Integrated 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

27. ILEAPS Integrated 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