Research

How do ecosystem-atmoshere interactions and their sensitivity and feedbacks to anthropogenic and climatic processes change across temporal and spatial scale? We focus on investigating the influence of spatiotemporal scale, ecology, and micrometeorology on how the atmosphere and surface communicate. Our lab observes and models these micrometeorological, ecological, and biogeochemical interactions of the surface with the atmosphere at regional to global scales, with a focus on anthropogenic influences to these interactions. Major research projects and tools we employ in our research are described below.

Projects

Current projects center on several themes focused on understanding emergent ecosystem and atmospheric phenomena at regional spatial scales (100s to 1000s of km) in spatially heterogenous or complex systems.

  • Carbon and water cycling in wetland-rich subboreal forests: Surface-atmosphere exchange of carbon dioxide, methane, and water vapor have been observed for nearly a decade off short and tall towers in the upper Midwest USA by our lab and collaborators to better understand regional land-atmosphere interactions. Ecosystems studied include wetlands, managed forests, and transitions between the two.
    • Regional fluxes : Contrasting environmental controls on regional CO2 and CH4 biogeochemistry (NSF)
    • Wetlands : Improving prediction of climate change impacts on wetland-rich landscapes (DOE)
    • Forests : Observing carbon fluxes and potential climate change impacts from forest land management (WI Focus on Energy, USDA, DOE LLNL)
  • Terrestrial-aquatic linkages of carbon: We look at the role of terrestrial transfers of carbon to aquatic systems affects site and regional carbon budgets in lake-rich regions and over the Great Lakes.
    • CyCLeS : Cycling of Carbon in Lake Superior (NSF)
    • Lakes : Carbon budgets of a north temperate lake district
  • Drivers of climate variability and carbon cycles in the U.S. Intermountain West: Several field projects have been combined with regional and global scale modeling efforts to better elucidate the impacts of drought, fire, and insect disturbance on carbon cycling in U.S. Rocky Mountain forests, alpine ecosystems, and grasslands at the diurnal to interannual time scale.
    • Rocky RACCOON : A Regional Atmospheric Continuous CO2 Network in the Rocky Mountains (NOAA)
    • ACME07 : Airborne Carbon in the Mountains Experiment 2007 (UW Graduate School)
  • Boundary layer - land surface interactions: Observations and models of mesoscale structure of convective and stable boundary layers have been studied over the Great Plains, the Rocky Mountains, the Great Lakes, and Amazonian forests using a variety of techniques and models.
    • SGP97 : Land surface influence on atmospheric boundary layer in the Great Plains (DOE ARM)
    • PEGASUS-PBL: A simple global model framework for integrating land use change effects into climate models (NSF)
    • Integration of Wind Energy Systems into Power Engineering Education Program (DOE)

Research Tools

  • Tower-based eddy covariance and micrometeorological observations: high-frequency measurements of atmospheric turbulence and fluctuations in scalars to directly observe surface-atmosphere trace-gas and energy exchange on scales of 0.1-10 km. The measurements can be related to biophysical state parameters, remotely-sensed radiative quantities or micrometeorological variables. . We have instrumented sites in northern Wisconsin and Michigan as part of the Chequamegon Ecosystem-Atmosphere Study. We have also worked on developing standardized algorithms to decompose the observed net fluxes into their components: respiration and photosynthesis.
  • Biogeochemical ecosystem models: We employ and modify a number of ecosystem and biogeochemical models to better understand carbon, water and energy transport between ecosystems and the atmosphere. We focus on incorporating heterogeneity into these models. Models we have used include Ecosystem Demography model (ED), PEGASUS, SiPNET , Biome-BGC, and LANDIS-II.
  • Model-data Bayesian parameter estimation: The mathematical technique of Bayesian hierarchical data assimilation can be used to optimally estimate model parameters for a given set of known observations and their uncertainty. We have applied these techniques, particularly Markov Chain Monte Carlo, to many observations we have made to better test hypotheses in non-linear models.
  • Tracer-transport budgets and inversions: Atmospheric tracer mass balance boundary layer budget and top-down transport inversions are used with atmospheric trace gases such as CO2 to constrain regional-scale surface-atmosphere interactions. Observations of trace gases from the surface, tall towers, aircraft, and in situ and spaceborne remote sensing are used with these methods.
  • Simple models of boundary layer structure and dynamics: The structure and dynamics of the lowest layer of the atmosphere, the boundary layer, is strongly controlled by surface exchanges of energy and water vapor. The variability of surface energy fluxes and surface meteorology, in turn, is related to terrestrial state variables, such as soil moisture, elevation/slope, vegetation type and ecosystem dynamics. We have been involved in several field campaigns focused on understanding these controls at the regional scale via airborne active and passive remote sensing and are also involved in modeling these interactions from the site to global scale using simplified prognostic models of boundary layer development and statistical downscaling techniques.
Topic revision: r13 - 2014-09-30 - 13:56:48 - AnkurDesai
 
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