PROGRAM TITLE: Ecology and Atmospheric Chemistry Branch ACTIVITY STREAM: Processes Research Working Group SCIENCE ELEMENT:
Biogeochemical Dynamics Ecological Systems and Dynamics NATIONAL AERONAUTICS AND SPACE ADMINISTRATIONSCIENTIFIC 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 below). 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 .