Download or read book Reducing the Uncertainty of North American Carbon Flux Estimates Using an Extended Atmospheric Carbon Dioxide Measurement Network written by Martha Peirce Butler and published by . This book was released on 2010 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: We evaluate North American carbon fluxes using a monthly global Bayesian synthesis inversion that includes well-calibrated carbon dioxide concentrations measured at continental flux towers. We employ the NASA Parameterized Chemistry Tracer Model (PCTM) for atmospheric transport and a modified version of the inversion used by the Atmospheric Tracer Transport Model Intercomparison Project (TransCom) with sub-continental resolution and annual variability of transport. We sub-sample carbon dioxide time series at four North American flux tower sites for mid-day hours to ensure sampling of a deep, well-mixed atmospheric boundary layer. The addition of these flux tower sites to a global network reduces North America mean annual flux uncertainty for 2001-2003 by 15% to 0.4 Pg yr−1 compared to a network without the tower sites. North American flux is estimated to be a net sink of 1.3 Pg C yr−1, within the uncertainty bounds of the result without the towers. Uncertainty reduction is found to be local to the regions within North America where the flux towers are located. Including the towers reduces covariances between regions within North America. We estimated potential future uncertainty reduction with simulated observations at North American sites that are now or planned to be instrumented for suitable carbon dioxide measurements. We also tested a micrometeorological adjustment to surface carbon dioxide measurements to approximate mid-continental-boundary-layer measurements. This adjustment can be calculated during mid-day hours using atmospheric measurements commonly available at flux tower sites. The atmospheric transport models used in global atmospheric inversions often do not have sufficient spatial or temporal resolution to capture small-scale variability in the continental boundary layer. We find that using mid-day hours of observations at continental sites, either with or without the micrometeorological adjustment, allows inclusion of continental sites in global atmospheric inversions. Increased continental observation density is necessary for estimating carbon fluxes with finer resolution in space and time.

Download or read book Assessment of Uncertainties in Atmospheric Transport and Surface Flux of Carbon from the North American Terrestrial Biosphere written by Caroline Normile and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The North American terrestrial biosphere acts as a strong sink of atmospheric CO2 and therefore plays a key role in the global carbon cycle. The atmospheric inversion approach is used to quantify the magnitude and distribution land-atmosphere carbon exchange, and requires accurate atmospheric transport and surface flux prior. We evaluate the relative sensitivity of simulated atmospheric total, biological, and fossil fuel CO2 mole fractions in the atmospheric boundary layer and integrated column over North America to changes in transport model and surface fluxes. We run three versions of a mesoscale model that incorporate different physics parameterization schemes and identical surface fluxes; we run the same mesoscale transport model with two different surface fluxes. All simulations are conducted for North America during 2008. Observed CO2 mole fractions reveal that seasonal amplitude ranges from 13 ppm in the West to over 34 ppm in the Midcontinent, and the models tested match these amplitudes to within a few ppm. Biology drives both the magnitude of the seasonal amplitude and regional differences in amplitude. Fossil fuels exhibit a seasonal cycle that is smaller than biological CO2, but not trivial. During the growing season, variations in surface fluxes yield mean differences in regionally, seasonally averaged atmospheric boundary layer total CO2 mole fractions that are larger for all regions than those resulting from varied transport model. The relative contributions of biological and fossil fuel to total mean difference CO2 show distinct quantitative patterns for varied flux and transport, and can provide information for attributing model-model differences in total CO2. Seasonal amplitude is much greater in the ABL than in the integrated column. Simulated total biological, and fossil fuel integrated column XCO2 are about 1/10th the magnitude of their signal in the atmospheric boundary layer. Flux and transport differences are also found in the integrated column at approximately 1/10th their atmospheric boundary layer values. While transport error is a significant problem for identifying terrestrial carbon fluxes, it is not an overwhelming one. Our work indicates that there is potential for remotely sensed integrated column XCO2 to distinguish between the flux signal and transport errors. Understanding transport error deserves more study, motivating current and future observational campaigns and modeling.While reducing transport uncertainty in atmospheric inversions has received considerable attention in recent years, quantification of carbon surface flux uncertainty remains a challenge. Model-observation studies can help identify model temporal and spatial limitations. To this end, we organize 166 CO2 flux tower measurement sites across North America by region, climate, and vegetation type into 23 groupings. The data span from 2000 through 2014 and are compared to output from eight atmospheric inverse estimates and 17 terrestrial biosphere models. We generate a mean year of observed and simulated net ecosystem exchange for each regional vegetation group and for each model. The NOAA CarbonTracker inverse estimates, major carbon flux inverse products, almost always underestimate amplitude of the seasonal cycle (biased positive relative to observations) and have a small spread. Furthermore, the inversions dont typically improve upon the prior with respect to the observations. Groups characterized by large seasonal amplitudes are not well represented by the models. For these groups, drawdown is underestimated. The terrestrial biosphere models often encompass the observations, but may have too much model-model variability. No one model is best everywhere. Model performance varies by vegetation and location. Certain biomes are well represented, certain biomes are not, and some models are reliably better than others. In general, evergreen forests in the north and east are better represented by the models than grasslands or crops in the midcontinent and southwest. Our large-scale, regional approach to model-observation analyses provides insight into the vegetation- and location-dependent performance of many inverse and terrestrial biosphere model estimates of land-atmosphere carbon exchange. This can help inform selection and application of surface flux priors in future inversions.

Download or read book Improving Bottom up and Top down Estimates of Carbon Fluxes in the Midwestern USA written by Aditsuda Jamroensan and published by . This book was released on 2013 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon dioxide (CO2) is the leading contributor to global warming and climate change. The increases in fossil fuel emissions, deforestation, and changes of land use have resulted in increased CO2 levels in the atmosphere from 280 ppm in 1765 to 390 ppm in 2010. Carbon mitigation policies for managing the biosphere to increase net CO2 uptake are dependent upon accurate knowledge of the biosphere fluxes. However, Northern Hemisphere bottom-up and top-down biosphere flux estimates show significant discrepancies, especially in North America. In this study, we design an analysis framework that integrates observations with models with the goal of reducing some of the key uncertainties in estimating CO2 fluxes and concentrations in the Midwest, USA.

Download or read book Atmospheric Carbon Dioxide Retrieved from the Greenhouse Gases Observing SATellite written by Austin James Cogan and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon dioxide is the largest anthropogenic contributor to global warming and atmospheric concentrations have rapidly increased since the start of the industrial revolution. Networks of surface in-situ carbon dioxide sensors provide precise and accurate measurements of the global carbon dioxide concentration, including large scale temporal, seasonal and latitudinal variations. However, these observations are too sparse to allow the establishment of sub-continental carbon budgets, limiting the accuracy of climate change projections and the ability to mitigate future levels of atmospheric carbon dioxide. Satellite observations can provide data with dense spatial and temporal coverage over regions poorly sampled by surface networks. Specifically, observations in the shortwave infrared region are well suited for constraining carbon fluxes as they can provide total column carbon dioxide with high sensitivity to the source and sink locations at the surface. The first dedicated greenhouse gases sensor, the Greenhouse gases Observing SATellite (GOSAT), was launched in January 2009 by the Japanese Aerospace eXploration Agency (JAXA) and has successfully started to acquire global observations of greenhouse gases, including carbon dioxide. The University of Leicester Full Physics (UOL-FP) retrieval algorithm has been designed to estimate total column carbon dioxide from GOSAT shortwave infrared observations. The initial results were compared to coincident ground based measurements for a number of locations and compared on a global scale to a model. This showed an accuracy and precison that should provide improved surface flux estimates. Additionally, a bias correction scheme was developed that reduced observed geographical biases, allowing surface flux uncertainties to be potentially reduced further. To further develop the UOL-FP retrieval algorithm, a simulator capable of creating realistic GOSAT observations was built, allowing the investigation of different retrieval algorithm modifications, which may lead to reduced source and sink flux uncertainties and therefore aid future climate change forecasts.

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.

Download or read book The Carbon Cycle written by T. M. L. Wigley and published by Cambridge University Press. This book was released on 2005-08-22 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reducing carbon dioxide (CO2) emissions is imperative to stabilizing our future climate. Our ability to reduce these emissions combined with an understanding of how much fossil-fuel-derived CO2 the oceans and plants can absorb is central to mitigating climate change. In The Carbon Cycle, leading scientists examine how atmospheric carbon dioxide concentrations have changed in the past and how this may affect the concentrations in the future. They look at the carbon budget and the "missing sink" for carbon dioxide. They offer approaches to modeling the carbon cycle, providing mathematical tools for predicting future levels of carbon dioxide. This comprehensive text incorporates findings from the recent IPCC reports. New insights, and a convergence of ideas and views across several disciplines make this book an important contribution to the global change literature.

Download or read book Commerce Justice Science and Related Agencies Appropriations for Fiscal Year 2007 written by United States. Congress. Senate. Committee on Appropriations. Subcommittee on Commerce, Justice, Science, and Related Agencies and published by . This book was released on 2006 with total page 2068 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Commerce Justice science and related agencies appropriations for 2008 written by United States. Congress. House. Committee on Appropriations. Subcommittee on Commerce, Justice, Science, and Related Agencies and published by . This book was released on 2007 with total page 1986 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Science the Departments of State Justice and Commerce and Related Agencies Appropriations for 2007 written by United States. Congress. House. Committee on Appropriations. Subcommittee on Science, State, Justice, and Commerce, and Related Agencies and published by . This book was released on 2006 with total page 2066 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book European Wind Atlas written by Ib Troen and published by . This book was released on 1989 with total page 656 pages. Available in PDF, EPUB and Kindle. Book excerpt: Beskriver resultatet af et europæisk samarbejde inden for EU vedr. vindenergiens udnyttelse ved at beskrive vindressourcen og de forskellige terraintypers indflydelse herpå.

Download or read book A U S Carbon Cycle Science Plan written by Carbon and Climate Working Group (U.S.) and published by . This book was released on 1999 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book North American Carbon Budget and Implications for the Global Carbon Cycle written by U. S. Climate Program and published by CreateSpace. This book was released on 2015-02-16 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: The carbon cycle chapter of the Strategic Plan for the U.S. Climate Change Science Program (CCSP) describes a plan to produce ..".a series of increasingly comprehensive and informative reports about the status and trends of carbon emissions and sequestration," each to be called a State of the Carbon Cycle Report (SOCCR). The Carbon Cycle Interagency Working Group's (CCIWG) Terms of Reference (TOR)1 for a first SOCCR elaborated this in June 2003, saying that what is envisioned is ..".a series of reports on the state of the carbon cycle designed to provide accurate, unbiased, and policy-relevant scientific information concerning the carbon cycle to a broad range of stakeholders. The two broad objectives for a State of the Carbon Cycle Report are (1) to summarize scientific knowledge about carbon cycle properties and changes, and (2) to provide scientific information for decision support and policy formulation concerning carbon." The first SOCCR will be CCSP Synthesis and Assessment Product (SAP) 2.2. The carbon cycle chapter of the CCSP Strategic Plan describes a long-term vision to regularly produce a comprehensive report on the state of the global carbon cycle within 10 years and projects that a near-term, prototype report focused on North America can be produced within 2 years. SAP 2.2 will summarize substantive information about North America's carbon budget. It also will serve as a prototype for future enhancement and extension to a global report. Subsequent reports are expected to evolve based on the lessons learned in producing earlier reports. SAP 2.2 will provide a synthesis and integration of the current knowledge of the North American (including land, atmosphere, and adjacent oceans) carbon budget and its context within the global carbon cycle. In a format useful to decisionmakers, it will (1) summarize our knowledge of carbon cycle properties and changes relevant to the contributions of and impacts2 upon the United States and the rest of the world, and (2) provide scientific information for U.S. decision support focused on key issues for carbon management and policy. SAP 2.2 will address carbon emissions; natural reservoirs and sequestration; rates of transfer; the consequences of changes in carbon cycling on land and the ocean; effects of purposeful carbon management; effects of agriculture, forestry, and natural resource management on the carbon cycle; and the socio-economic drivers and consequences of changes in the carbon cycle. It will cover North America's land, atmosphere, inland waters, and adjacent oceans. It will include an analysis of North America's carbon budget that will document the state of knowledge and quantify best estimates (i.e., consensus, accepted, official) and uncertainties. This analysis will provide a baseline against which future results from the North American Carbon Program (NACP) can be compared. SAP 2.2 will be coordinated with other CCSP synthesis and assessment products as appropriate.

Download or read book Carbon Dioxide Information Analysis Center Catalog of Data Bases and Reports written by and published by . This book was released on 1989 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Toward Improved Regional Estimates of Carbon Dioxide Sources and Sinks Through Coupled Carbon atmospheric Data Assimilation written by Hans Weiteng Chen and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Accurate estimates of regional carbon dioxide (CO2) sources and sinks are necessary to further our understanding of the carbon cycle and improve predictions of future climate change. CO2 surface fluxes can be constrained using atmospheric CO2 observations combined with atmospheric transport models through so-called top-down or inverse methods. At regional scales, however, inverse estimates of CO2 fluxes have been shown to be sensitive to errors in model representation of atmospheric transport. How to account for such atmospheric transport errors in inversions is currently not well understood.This dissertation examines the impact of atmospheric transport errors on simulated atmospheric CO2 mole fractions and inferred CO2 fluxes at subcontinental scales and hourly to monthly time scales. We first investigate how much space for improvement there is in two contemporary CO2 analysis datasets by comparing CO2 mole fractions from the analyses with airborne in situ measurements of CO2 from the Atmospheric Carbon and Transport - America field campaigns in summer 2016 and winter 2017. The analyses show an overall good agreement with observations except for large biases in near-surface CO2 mole fractions in the Mid-Atlantic region of the United States during summer, which suggests that CO2 fluxes can be further optimized in this region. Next, we quantify how transport errors due to uncertainties in meteorological initial conditions propagate to errors in atmospheric CO2 mole fractions through ensemble sensitivity experiments in a regional mesoscale model. Transport errors in CO2 are found to be of comparable magnitude and share similar spatiotemporal characteristics as errors due to uncertainties in CO2 fluxes on sub-monthly time scales. Finally, we present the development of a coupled carbon--atmospheric data assimilation system for regional CO2 flux inversion. This data assimilation system uses the ensemble Kalman Filter to optimize both meteorological variables and CO2 mole fractions and fluxes. Coupling the atmospheric and carbon states allows us to investigate the role of atmospheric transport errors in the CO2 flux optimization. The data assimilation system is tested in a series of perfect model experiments with synthetic observations to examine how well the CO2 flux inversion performs when different types of errors are introduced.

Download or read book Carbon Dioxide Information Analysis Center World Data Center A for Atmospheric Trace Gases written by Carbon Dioxide Information Analysis Center (U.S.) and published by . This book was released on 1993 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Our Changing Planet written by and published by . This book was released on 2002 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Phenology of Ecosystem Processes written by Asko Noormets and published by Springer Science & Business Media. This book was released on 2009-06-19 with total page 281 pages. Available in PDF, EPUB and Kindle. Book excerpt: Terrestrial carbon balance is uncertain at the regional and global scale. A significant source of variability in mid-latitude ecosystems is related to the timing and duration of phenological phases. Spring phenology, in particular, has disproportionate effects on the annual carbon balance. However, the traditional phenological indices that are based on leaf-out and flowering times of select indicator species are not universally amenable for predicting the temporal dynamics of ecosystem carbon and water exchange. Phenology of Ecosystem Processes evaluates current applications of traditional phenology in carbon and H2O cycle research, as well as the potential to identify phenological signals in ecosystem processes themselves. The book summarizes recent progress in the understanding of the seasonal dynamics of ecosystem carbon and H2O fluxes, the novel use of various methods (stable isotopes, time-series, forward and inverse modeling), and the implications for remote sensing and global carbon cycle modeling. Each chapter includes a literature review, in order to present the state-of-the-science in the field and enhance the book’s usability as an educational aid, as well as a case study to exemplify the use and applicability of various methods. Chapters that apply a specific methodology summarize the successes and challenges of particular methods for quantifying the seasonal changes in ecosystem carbon, water and energy fluxes. The book will benefit global change researchers, modelers, and advanced students.