Download or read book Final Report On DOE Project DE FG02 06ER64319 Data Model Assimilation at the FACE and AmeriFlux Sites Toward Predictive Understanding of Carbon Sequestration at Ecosystem and Regional Scales written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Data Model Assimilation at the FACE and AmeriFlux Sites Toward Predictive Understanding of Carbon Sequestration at Ecosystem and Regional Scales written by and published by . This book was released on 2013 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: The project was conducted during the period from 9/1/2007 to 8/31/2011 with three major tasks: (1) development of data assimilation (DA) techniques for terrestrial carbon research; (2) applications of DA techniques to analysis of carbon cycle at Duke and other FACE sites; and (3) inverse analysis at AmeriFlux sites. During this period, we have developed a variety of techniques, including (1) ensemble Kalman filter to estimate model parameters or state variables (Gao et al. 2011), (2) Conditional inversion to estimate parameters of a carbon cycle model (Wu et al. 2009), and (3) various methods to quantify uncertainty of estimated parameters and predicted C sinks (e.g., Weng et al. 2011), and (4) information theory to evaluate information content of different model structures and data sets (Weng and Luo 2011). We applied the DA techniques to and did modeling at the Duke FACE and other global change experimental sites. We addressed the following issues: (1) interactive effects of CO2, warming and precipitation on ecosystem processes (e.g., Luo et al. 2008, Weng and Luo 2008, Zhou et al. 2008), (2) effects of warming on estimated parameters related to photosynthesis and residence times (Zhou et al. 2010); and (3) uncertainty in estimated parameters and predicted C sequestration (Gao et al. 2011, Weng and Luo 2011). In addition, we have done data assimilation to estimate carbon residence and carbon sequestration in US continent (Zhou and Luo 2008) and temperature sensitivity at the global scale (Zhou et al. 2009).

Download or read book Final Report for Award DE FG02 03ER63640 written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The carbon isotope ratios of carbon dioxide fluxes from terrestrial ecosystems are key measurements needed to constrain interpretations of carbon sinks in North American carbon cycle analyses. The completed research was a multi-faceted effort addressing photosynthetic and respiratory isotope exchanges across the biosphere-atmosphere boundary at five AmeriFlux sites (Harvard Forest, Howland Forest, Rannalls Ranch, Niwot Ridge Forest, and Wind River Crane Site), spanning the dominant ecosystem types of the United States. The sampling and analysis protocols developed in this project have become the fundamental analytical approach for all sites measuring ecosystem isotope studies across the United States and Canada. It is the first network of long-term observations to characterize the isotopic composition of the biosphere-atmosphere CO2 flux. We focused on understanding the magnitude of changes in the carbon isotope ratio of respiration and of photosynthetic discrimination on seasonal and interannual bases. Focusing at AmeriFlux sites provided a direct link to NEE measurements associated with studies of the North American carbon cycle and an opportunity to provide mechanistic insights relating observed isotope changes and the controls over carbon sequestration and loss on seasonal and interannual bases. An additional component of our research linked directly with eddy covariance monitoring to partition NEE into assimilation and respiratory components. The completed project promoted cross-site analyses and resulting publications applicable at AmeriFlux and other long-term carbon cycle research sites. Lastly, the online monitoring of carbon dioxide in the Salt Lake Valley and the intermittent monitoring of absolute carbon dioxide concentrations at different AmeriFlux sites contributed public awareness and data sets that can be used in public education and as a basis for public policies related to carbon dioxide.