PROGRAM TITLE: 	Ecology and Atmospheric Chemistry Branch
ACTIVITY STREAM: 	Processes Research Working Group
SCIENCE ELEMENT: 	Biogeochemical Dynamics
				Ecological Systems and Dynamics


SCIENTIFIC MERIT: The goals of the Ecology and Atmospheric 
Chemistry Branch within the Science Division are to understand (1) 
the structure and function of global terrestrial and oceanic 
ecosystems, their interactions with the atmosphere and hydrosphere, 
and their role in the cycling of the major biogeochemical elements 
and water; and (2) the physics, chemistry, and transport processes of 
the Earth's atmosphere (troposphere and stratosphere) with which to 
assess its susceptibility to change.  The Branch's treatment of the 
Earth system is consistent with the IPCC and WMO/UNEP scientific 
assessments of climate change and stratospheric ozone depletion.  Of 
most interest and highest priority are phenomena of global 
significance that occur over decades to a few centuries and in which 
human activities play a major role: e.g. stratospheric ozone depletion, 
tropical deforestation, biomass burning and its atmospheric 
consequences, oceanic primary productivity, ecosystem functioning 
in a changing environment, and changes in the oxidizing capacity of 
the troposphere.  Of particular concern is understanding the 
processes that control each of these important global phenomena.  
The Branch is separated into four individual programs: Terrestrial 
Ecology, Tropospheric Chemistry, Stratospheric Chemistry, and Ocean 
Biogeochemistry.  Each is described briefly below:
Terrestrial Ecology: This program conducts research in terrestrial 
ecology and biogeochemistry, aspects of hydrology (focusing on the 
biologically-mediated components of the hydrologic cycle), and 
remote sensing theory as it applies to the study of terrestrial 
ecosystems.  Field observations and experiments, analysis of aircraft- 
and space-based remote sensing data, and ecological modeling are 
supported.  The program emphasizes understanding of processes and 
the use of remote sensing observations and modeling to extend this 
understanding to larger spatial and temporal scales.  Areas of 
emphasis include research on major sources and sinks of greenhouse 
gases, especially methane, nitrous oxide, and carbon dioxide, the 
biological processes that control trace gas fluxes and can affect the 
accuracy of predictions of future concentrations, the development of 
models to evaluate impacts of climatic change on ecosystem 
processes, and the scaling of ecological and hydrological processes on 
landscapes, in order to quantify ecosystems' links with the 
atmosphere.  The Boreal Ecosystem-Atmosphere Study (BOREAS) is 
being conducted jointly with Canada, NOAA, NSF and EPA in order to 
study interactions between the boreal forest biome and the 
atmosphere. Recent accomplishments include identifying constraints 
on global methane budgets with respect to emissions from northern 
wetlands, using isotopic analyses to constrain the total size of the 
global ocean CO2 sink, quantifying and investigating the 
consequences of smaller deforestation rates in Brazil than previously 
published (jointly with the Landsat Pathfinder), and quantifying 
hydrologic and energy exchanges with the atmosphere of grassland 
study sites in the Konza Prairie as part of the FIFE experiment.
Tropospheric Chemistry: This program conducts research aimed at 
understanding the large-scale influences of anthropogenic and 
natural processes on the oxidative capacity of the troposphere.  It 
has emphasized field campaigns in the tropics and at high northern 
latitudes designed to study boundary layer fluxes and exchanges 
with the free troposphere, campaigns in the western Pacific to 
investigate the distribution and concentration of materials from the 
Asian continental plume and a campaign in the South Atlantic to 
study biomass burning products from South America and Africa.  
Instrumentation testing and evaluation to understand and improve 
measurement capabilities of airborne instruments and the 
development of new instrumentation for airborne and spaceborne 
platforms are also key elements of the program.  Areas of emphasis 
include understanding the role of biomass burning and stratospheric 
inclusions in determining the high ozone concentrations seen over 
the South Atlantic, and understanding the impact of industrially-
affected air off the Asian continent on the clean air of the central 
Pacific.  Major recent accomplishments include determining the 
boundary layer-free troposphere exchanges of CO2 and other trace 
gases in tropical Brazil as part of the ABLE 2A/2B missions, 
determining the exchange with the free troposphere of methane 
from Alaskan and Canadian wetlands as part of ABLE 3A/3B, and 
measuring the contribution to ozone concentrations in the South 
Atlantic from biomass burning constituents derived from both Africa 
and South America.
Stratospheric Chemistry: This program conducts research aimed at 
understanding the processes by which large-scale anthropogenic and 
natural processes influence the chemistry of the stratosphere.  In 
recent years, the primary focus has been the influence of CFC's and 
other man-made chemicals on stratospheric chemistry in both the 
Antarctic and the Arctic.  The program has emphasized airborne 
sampling campaigns in both Arctic and Antarctic, to observe first-
hand the anthropogenic perturbations on stratospheric chemistry in 
those regions, supported laboratory process and kinetics studies, to 
evaluate the mechanisms and rates of possible processes and make 
predictions that can be verified in the field, participated in an 
evaluation of the potential impacts of high speed aircraft on the 
chemistry of the stratosphere, implemented a portion of the Network 
for Detection of Stratospheric Change, in order to verify the ground-
level consequences of ozone depletion, evaluated the quality of 
satellite observations of ozone concentrations, and developed new 
instrumentation for the next generation of airborne platforms.  
Recent accomplishments include observations of perturbed chemistry 
in the northern high latitude winter
stratosphere, indicating the potential for significant ozone depletion, 
direct observational evidence of the role of heterogeneous chemistry 
on sulfate aerosols in altering the chemical composition of the lower 
stratosphere at mid- and high latitudes, and a definitive 
establishment of cause and effect between atmospheric chlorine and 
bromine and the severe seasonal antarctic ozone depletion.
Ocean Biogeochemistry: The ocean biogeochemistry program seeks to 
develop a quantitative understanding of the global ocean 
biogeochemical cycles, including fluxes of elements between the 
oceans, the atmosphere and land.  The major emphasis has been on 
the use of remote sensing imagery to understand the magnitude of 
and processes controlling primary productivity in the oceans, and 
thus the oceanic contribution to the global carbon cycle.  Estimates of 
primary production, biomass and dissolved organic carbon are of 
primary interest, and modeling studies seek to understand the 
relative importance of biogeochemical and physical processes in 
controlling ocean carbon pathways.  In-situ observations of these and 
associated parameters have been supported to verify measurements 
taken from both aircraft and spaceborne platforms, and to remove 
the atmospheric and ocean optical effects on remote sensing data.  
The physiology of phytoplankton is being investigated to provide 
input for process-based modeling of global ocean systems, and to 
understand the effects of UV light on marine productivity.
All scientific activities within the Ecology and Atmospheric Chemistry 
Branch are peer-reviewed.  In addition, both formal and informal 
advisory panels assist program managers in setting priorities for 
research directions in each individual program.  Close ties to 
international scientific assessment
activities and IGBP/WCRP programs have been established (see 
STAKEHOLDERS:   Specific links have been established between 
programs in the Ecology and Atmospheric Chemistry branch and the 
following IGBP core projects: IGAC (and its elements APARE and 
STARE), GCTE, and JGOFS.  In addition, investigators from each 
program, and even program managers, have played active roles in 
contributing to or coordinating assessment activities for both the 
WMO/UNEP Stratospheric Ozone Assessments, the IPCC Science 
Assessments, and the IPCC Impact Assessment.  Cooperative 
interactions with other federal agencies within the USGCRP include 
NSF, NOAA, ONR, EPA and the USDA Forest Service.  Policy-level 
stakeholders are described below.
POLICY RELEVANCE:   These programs are among the most policy-
relevant in the USGCRP.  The research results from the stratospheric 
chemistry program, for example, have played major roles in the 
discussions leading up to and in revisions to the Montreal Protocol.  
The terrestrial ecology and tropospheric chemistry program results 
have major implications for the discussions now taking
place for the Climate Convention, the Forestry Convention, and 
possibly Desertification and Biodiversity (ecology).  The research 
results on the carbon cycle and marine productivity from the ocean 
biogeochemistry program have important implications for the 
Climate CO and in assessment of coastal ecosystem health.  The 
program forms an integral part of GOOS and Health of the Ocean 
panel scope.  In each case, there are a mixture of short-term (less 
than 5 year) and longer term (greater than 5 year) payoffs for 
policy-level interests.  For example, calculations from current models 
using data from the terrestrial ecology and tropospheric chemistry 
programs suggest that the tropical land-use source of C to the 
atmosphere is possibly under 1 GtC/yr, a figure which will have 
immediate implications for both the Climate Convention and the 
Forestry Convention.  On longer time-scales, data on habitat 
fragmentation in both North and South America, and its influence on 
ecosystem processes, will be important in policy-level debates on 
biodiversity and ecosystem management .