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Great Lakes — ChEAS

This investigation seeks to bridge the gap between detailed eddy flux measurements made at local scales (for which regional representativeness is difficult to establish) and regional information provided by inversion studies (whose results are difficult to apply to particular ecosystems because of their coarse resolution). Inverting atmospheric observations using simulated tracer transport over vegetated land surfaces requires careful evaluation of interactions among surface energy budgets, ecosystem carbon flux, and atmospheric turbulence and convection (the “rectifier effect“) which can confound the inversion procedure: we seek to evaluate this effect in nature and in a series of models. Technical and financial obstacles preclude a flux network of sufficient density to resolve sub-regional spatial patterns in carbon flux: we seek a testable method for extrapolation of these fluxes using modeling, remote sensing, and atmospheric data.


We have coupled a self-consistent model (SiB2) of biophysical and biogeochemical exchanges at the land surface to local-scale turbulence models, to a mesoscale model, and to an atmospheric GCM. Vegetation is parameterized according to satellite imagery, and the models predict observable quantities such as energy fluxes and CO2 concentrations. The coupled models are quite successful at predicting variations of latent and sensible heat fluxes, CO2 fluxes, and CO2 concentrations at multiple spatial scales.

We have also studied stable isotope fractionation of CO2 in the ecosystems surrounding the tower, applied tower and nearby radar wind profiler data to study the CO2 rectifier effect, and investigated new methods for regional inverse modeling using tall tower and aircraft data.

Download documents, presentations, and data:
• Filled micrometrological “driver” data for site
• Photos of the site
• Development of model parameters from satellite data and maps
• Parameter sensitivity study (GLUE)
• Presentation on local RAMS simulations
• December 2000 Summary Report to NIGEC
• Baker et al manuscript evaluating SiB simulations against observed fluxes
• Ni Zhang’s M.S. Thesis on Simulated and Observed Rectifier Effects
• Denning et al manuscript on local-scale SiB-RAMS simulations
• Nicholls et al manuscript on regional CO2 simulations in SiB-RAMS
• Uliasz et al draft manuscript on mesoscale inverse modeling