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Ecosystem-Atmosphere Exchange of Carbon, Water and Energy over a Mixed Deciduous Forest in the Midwest

Description: During the project period we continued to conduct long-term (multi-year) measurements, analysis, and modeling of energy and mass exchange in and over a deciduous forest in the Midwestern United States, to enhance the understanding of soil-vegetation-atmosphere exchange of carbon. At the time when this report was prepared, results from nine years of measurements (1998 - 2006) of above canopy CO2 and energy fluxes at the AmeriFlux site in the Morgan-Monroe State Forest, Indiana, USA (see Table 1), were available on the Fluxnet database, and the hourly CO2 fluxes for 2007 are presented here (see Figure 1). The annual sequestration of atmospheric carbon by the forest is determined to be between 240 and 420 g C m-2 a-1 for the first ten years. These estimates are based on eddy covariance measurements above the forest, with a gap-filling scheme based on soil temperature and photosynthetically active radiation. Data gaps result from missing data or measurements that were rejected in qua)lity control (e.g., during calm nights). Complementary measurements of ecological variables (i.e. inventory method), provided an alternative method to quantify net carbon uptake by the forest, partition carbon allocation in each ecosystem components, and reduce uncertainty on annual net ecosystem productivity (NEP). Biometric datasets are available on the Fluxnext database since 1998 (with the exclusion of 2006). Analysis for year 2007 is under completion.
Date: December 17, 2012
Creator: Dragoni, Danilo; Schmid, Hans Peter; Grimmond, C.S.B.; Randolph, J.C. & White, J.R.
Partner: UNT Libraries Government Documents Department

Final Technical Report [Carbon Data Assimilation with a Coupled Ensemble Kalman Filter]

Description: We proposed (and accomplished) the development of an Ensemble Kalman Filter (EnKF) approach for the estimation of surface carbon fluxes as if they were parameters, augmenting the model with them. Our system is quite different from previous approaches, such as carbon flux inversions, 4D-­‐Var, and EnKF with approximate background error covariance (Peters et al., 2008). We showed (using observing system simulation experiments, OSSEs) that these differences lead to a more accurate estimation of the evolving surface carbon fluxes at model grid-­‐scale resolution. The main properties of the LETKF-­‐C are: a) The carbon cycle LETKF is coupled with the simultaneous assimilation of the standard atmospheric variables, so that the ensemble wind transport of the CO2 provides an estimation of the carbon transport uncertainty. b) The use of an assimilation window (6hr) much shorter than the months-­‐long windows used in other methods. This avoids the inevitable “blurring” of the signal that takes place in long windows due to turbulent mixing since the CO2 does not have time to mix before the next window. In this development we introduced new, advanced techniques that have since been adopted by the EnKF community (Kang, 2009, Kang et al., 2011, Kang et al. 2012). These advances include “variable localization” that reduces sampling errors in the estimation of the forecast error covariance, more advanced adaptive multiplicative and additive inflations, and vertical localization based on the time scale of the processes. The main result has been obtained using the LETKF-­‐C with all these advances, and assimilating simulated atmospheric CO2 observations from different observing systems (surface flask observations of CO2 but no surface carbon fluxes observations, total column CO2 from GoSAT/OCO-­‐2, and upper troposphere AIRS retrievals). After a spin-­‐up of about one month, the LETKF-­‐C succeeded in reconstructing the true evolving surface fluxes of carbon at a model grid ...
Date: August 30, 2013
Creator: Kalnay, Eugenia
Partner: UNT Libraries Government Documents Department

Quantifying Climate Feedbacks from Abrupt Changes in High-Latitude Trace-Gas Emissions

Description: Our overall goal was to quantify the potential for threshold changes in natural emission rates of trace gases, particularly methane and carbon dioxide, from pan-arctic terrestrial systems under the spectrum of anthropogenically forced climate warming, and the extent to which these emissions provide a strong feedback mechanism to global climate warming. This goal is motivated under the premise that polar amplification of global climate warming will induce widespread thaw and degradation of the permafrost, and would thus cause substantial changes in the extent of wetlands and lakes, especially thermokarst (thaw) lakes, over the Arctic. Through a coordinated effort of field measurements, model development, and numerical experimentation with an integrated assessment model framework, we have investigated the following hypothesis: There exists a climate-warming threshold beyond which permafrost degradation becomes widespread and thus instigates strong and/or sharp increases in methane emissions (via thermokarst lakes and wetland expansion). These would outweigh any increased uptake of carbon (e.g. from peatlands) and would result in a strong, positive feedback to global climate warming.
Date: April 26, 2013
Creator: Schlosser, Courtney Adam; Walter-Anthony, Katey; Zhuang, Qianlai & Melillo, Jerry
Partner: UNT Libraries Government Documents Department

Three-Dimensional Imaging and Quantification of Biomass and Biofilms in Porous Media

Description: A new method to resolve biofilms in three dimensions in porous media using high-resolution synchrotron-based x-ray computed microtomography (CMT) has been developed. Imaging biofilms in porous media without disturbing the natural spatial arrangement of the porous media and associated biofilm has been a challenging task, primarily because porous media generally precludes conventional imaging via optical microscopy; x-ray tomography offers a potential alternative. One challenge for using this method is that most conventional x-ray contrast agents are water-soluble and easily diffuse into biofilms. To overcome this problem, silver-coated microspheres were added to the fluid phase to create an x-ray contrast that does not diffuse into the biofilm mass. Using this approach, biofilm imaging in porous media was accomplished with sufficient contrast to differentiate between the biomass- and fluid-filled pore spaces. The method was validated by using a two-dimensional micro-model flow cell where both light microscopy and CMT imaging were used to im age the biofilm. The results of this work has been published in Water Resources Research (Iltis et al., 2010). Additional work needs to be done to optimize this imaging approach, specifically, we find that the quality of the images are highly dependent on the coverage of the biofilm with Ag particles, - which means that we may have issues in dead-end pore space and for very low density (fluffy) biofilms. What we can image for certain with this technique is the biofilm surface that is well-connected to flow paths and thus well-supplied with nutrients etc.
Date: October 10, 2012
Creator: Wildenschild, Dorthe
Partner: UNT Libraries Government Documents Department

Final Report for "Improved Representations of Cloud Microphysics for Model and Remote Sensing Evaluation using Data Collected during ISDAC, TWP-ICE and RACORO

Description: We were funded by ASR to use data collected during ISDAC and TWP-ICE to evaluate models with a variety of temporal and spatial scales, to evaluate ground-based remote sensing retrievals and to develop cloud parameterizations with the end goal of improving the modeling of cloud processes and properties and their impact on atmospheric radiation. In particular, we proposed to: 1) Calculate distributions of microphysical properties observed in arctic stratus during ISDAC for initializing and evaluating LES and GCMs, and for developing parameterizations of effective particle sizes, mean fall velocities, and mean single-scattering properties for such models; 2) Improve representations of particle sizes, fall velocities and scattering properties for tropical and arctic cirrus using TWP-ICE, ISDAC and M-PACE data, and to determine the contributions that small ice crystals, with maximum dimensions D less than 50 μm, make to mass and radiative properties; 3) Study fundamental interactions between clouds and radiation by improving representations of small quasi-spherical particles and their scattering properties. We were additionally funded 1-year by ASR to use RACORO data to develop an integrated product of cloud microphysical properties. We accomplished all of our goals.
Date: June 11, 2003
Creator: McFarquhar, Greg M.
Partner: UNT Libraries Government Documents Department

he Impact of Primary Marine Aerosol on Atmospheric Chemistry, Radiation and Climate: A CCSM Model Development Study

Description: This project examined the potential large-scale influence of marine aerosol cycling on atmospheric chemistry, physics and radiative transfer. Measurements indicate that the size-dependent generation of marine aerosols by wind waves at the ocean surface and the subsequent production and cycling of halogen-radicals are important but poorly constrained processes that influence climate regionally and globally. A reliable capacity to examine the role of marine aerosol in the global-scale atmospheric system requires that the important size-resolved chemical processes be treated explicitly. But the treatment of multiphase chemistry across the breadth of chemical scenarios encountered throughout the atmosphere is sensitive to the initial conditions and the precision of the solution method. This study examined this sensitivity, constrained it using high-resolution laboratory and field measurements, and deployed it in a coupled chemical-microphysical 3-D atmosphere model. First, laboratory measurements of fresh, unreacted marine aerosol were used to formulate a sea-state based marine aerosol source parameterization that captured the initial organic, inorganic, and physical conditions of the aerosol population. Second, a multiphase chemical mechanism, solved using the Max Planck Institute for Chemistry’s MECCA (Module Efficiently Calculating the Chemistry of the Atmosphere) system, was benchmarked across a broad set of observed chemical and physical conditions in the marine atmosphere. Using these results, the mechanism was systematically reduced to maximize computational speed. Finally, the mechanism was coupled to the 3-mode modal aerosol version of the NCAR Community Atmosphere Model (CAM v3.6.33). Decadal-scale simulations with CAM v.3.6.33, were run both with and without reactive-halogen chemistry and with and without explicit treatment of particulate organic carbon in the marine aerosol source function. Simulated results were interpreted (1) to evaluate influences of marine aerosol production on the microphysical properties of aerosol populations and clouds over the ocean and the corresponding direct and indirect effects on radiative transfer; (2) atmospheric burdens of ...
Date: May 20, 2013
Creator: Keene, William C. & Long, Michael S.
Partner: UNT Libraries Government Documents Department


Description: An approach to calculating the transfer of isotopic tracers in reservoir models is outlined that takes into account the effects of isotopic fractionation at phase boundaries without any significant approximations. Simultaneous variations in both the rare isotopic tracer and the total elemental (the sum of its isotopes) concentration are considered. The proposed procedure is applicable to most models of the carbon cycle and a four-box model example is discussed. Although the exact differential equations are non-linear, a simple linear approximation exists that gives insight into the nature of the solution. The treatment will be in terms of isotopic ratios which are the directly measured quantities.
Date: February 1, 1980
Creator: Tans, Pieter P.
Partner: UNT Libraries Government Documents Department


Description: The relatively long lifetime of droplets in atmospheric haze and fog in comparison with similar droplets of pure water is attributed to the presence of a monolayer of surfactant film and to the accumulation Of soluble salts from chemical reactions. The lifetime of these droplets is a significant factor in the evaluation of the role of heterogeneous aqueous chemical reactions occurring in the troposphere. Several mechanisms of SO{sub 2} oxidation in the presence of liquid water are investigated. It is shown that soot-catalyzed oxidation of sulfur dioxide could be responsible for the high level of sulfate concentration observed in the coastal industrial areas.
Date: April 1, 1984
Creator: Toossi, R. & Novakov, T.
Partner: UNT Libraries Government Documents Department


Description: The Hanford Grout Lysimeter Facility (HGLF) will be constructed to test the leaching and migration of radioactive and nonradioactive tracers embedded in a solidification agent (grout) under actual burial conditions in Hanford soil. Three different water treatment rates will be used: natural precipitation, 4 times and 8 times natural precipitation. Six lysimeters will be assembled. Each unit will measure 6 feet in diameter, 25 feet deep. Their construction and instrumentation will be performed during June-July, 1984 by J. A. Jones Construction Company and/or their subcontractor. The routine monitoring will be performed by Battelle staff over a 5.5 year period beginning in November 1984. The total estimated project cost will be approximately $200,000. The only anticipated environmental impact from this project will be a temporary nuisance-type local dust problem during the construction phase. This will not be a detriment to the environment. The results of dose calculations indicate that dose rates from the grouted waste cans will be quite low when the cans are covered by a meter or more of earth. Dose rates at or near the surface of the individual cans are not high enough to preclude their handling. The facility area will be fenced, posted as a radiation zone and operated under a radiation work procedure.
Date: June 1984
Creator: Bruno, G. A.
Partner: UNT Libraries Government Documents Department

Surface Environmental Surveillance Procedures Manual

Description: This manual establishes the procedures for the collection of environmental samples and the performance of radiation surveys and other field measurements. Responsibilities are defined for those personnel directly involved in the collection of samples and the performance of field measurements.
Date: February 1990
Creator: Hanf, R. W. & Dirkes, R. L.
Partner: UNT Libraries Government Documents Department

Old-field Community, Climate and Atmospheric Manipulation

Description: We are in the process of finishing a number of laboratory, growth chamber and greenhouse projects, analyzing data, and writing papers. The projects reported addressed these subjects: How do climate and atmospheric changes alter aboveground plant biomass and community structure; Effects of multiple climate changes factors on plant community composition and diversity: what did we learn from a 5-year open-top chamber experiment using constructed old-field communities; Do atmospheric and climatic change factors interact to alter woody seedling emergence, establishment and productivity; Soil moisture surpasses elevated CO{sub 2} and temperature in importance as a control on soil carbon dynamics; How do climate and atmospheric changes alter belowground root and fungal biomass; How do climate and atmospheric changes alter soil microarthropod and microbial communities; How do climate and atmospheric changes alter belowground microbial function; Linking root litter diversity and microbial functioning at a micro scale under current and projected CO{sub 2} concentrations; Multifactor climate change effects on soil ecosystem functioning depend on concurrent changes in plant community composition; How do climate and atmospheric changes alter aboveground insect populations; How do climate and atmospheric changes alter festuca endophyte infection; How do climate and atmospheric changes soil carbon stabilization.
Date: November 1, 2009
Creator: Classen, Aimee
Partner: UNT Libraries Government Documents Department


Description: In a continuing effort for the U.S. Department of Energy, Pacific Northwest Laboratory (PNL) is conducting ground-water monitoring at the Hanford Site, near Richland, Washington. This document contains the data listing of monitoring results obtained by PNL and Westinghouse Hanford Company during the period January through December 1989. Samples taken during 1989 were analyzed and reported by United States Testing Company, Inc., Richland, Washington. The data listing contains all chemical results (above contractual reporting limits) and radiochemical results (for which the result is larger than two times the total error).
Date: December 1, 1990
Creator: Bryce, R. W. & Gorst, W. R.
Partner: UNT Libraries Government Documents Department

Ecosystem Controls on C & N Sequestration Following Afforestation of Agricultural Lands

Description: In our project, we proposed to continue analysis of our available soil samples and data, and to develop new studies to answer the following objectives: Objective 1) Broaden field based studies of ecosystem C and N compartments to enhance current understanding of C and N sequestration and dynamics. Objective 2) Improve our understanding of mechanism controlling C and N stabilization and dynamics. Objective 3) Investigate the interrelated role of soil temperature and organism type and activity as controlling mechanism in SOC dynamics and sequestration.
Date: March 5, 2013
Creator: E.A. Paul, S.J. Morris, R.T. Conant
Partner: UNT Libraries Government Documents Department

Final Report for DOE Grant DE-FG02-07ER64470 [“Incorporation of the HYbrid Coordinate Ocean Model (HYCOM) into the Community Climate System Model (CCSM): Evaluation and Climate Applications”]

Description: The primary goal of the project entitled “Incorporation of the HYbrid Coordinate Ocean Model (HYCOM) into the Community Climate System Model (CCSM): Evaluation and Climate Applications” was to systematically investigate the performance of the HYbrid Coordinate Ocean Model (HYCOM) as an alternative oceanic component of the NCAR’s Community Climate System Model (CCSM). We have configured two versions of the fully coupled CCSM3/HYCOM: one with a medium resolution (T42) Community Atmospheric Model (CAM) and the other with higher resolution (T85). We have performed a comprehensive analysis of the 400-year fully coupled CCSM3/HYCOM simulations and compared the results with those from CCSM3/POP and with climatological observations, and also we have performed tuning of critical model parameters, including Smagorinsky viscosity, isopycnal diffusivity, and background vertical diffusivity. The analysis shows that most oceanic features are well represented in the CCSM3/HYCOM. The coupled CCSM3/HYCOM (T42) has been integrated for 400 years, and the results have been archived and transferred to the High Performance Computer in the Florida State Univesity. In the last year, we have made comprehensive diagnostics of the long-term simulations by the comparison with the original CCSM3/POP simulation and with the observations. To gain some understanding of the model biases, the mean climate and modes of climate variability of the two models are compared with observations. The examination includes the Northern and Southern Annular Modes (NAM and SAM), the Pacific-North-American (PNA) pattern, the Atlantic Multidecadal Oscillation (AMO), and the main Southern Ocean SST mode. We also compared the performance of ENSO simulation in the coupled models. This report summarizes the main findings from the comparison of long-term CCSM3/HYCOM and CCSM3/POP simulations.
Date: March 18, 2013
Creator: Chassignet, Eric P
Partner: UNT Libraries Government Documents Department

Evaluating the Contribution of Climate Forcing and Forest Dynamics to Accelerating Carbon Sequestration by Forest Ecosystems in the Northeastern U.S.

Description: We used 10 Hz eddy flux signals and 0.2 Hz incident radiation (global shortwave and PAR) records from Harvard Forest (Massachusetts) and Tapajos National Forest (Brazil) to establish empirical relationships among directly measured cloud type and cover percentage and corresponding PAR fluctuations and its diffuse fraction. In future work such a cloud characterization will be related to water and light use efficiency estimates for each of these ecosystems. We developed empirical relationships to link sky cover type and fraction (measured with the ceilometer) to incident direct and diffuse PAR. We developed a methodology for constructing synthetic incident solar radiation time series based on operational reports of sky cover and cloud type from National Weather Service METAR reports. The aim of this work is to document the temporal and spectral properties radiation incident on the canopy, as a first step toward developing a sky-type parameterization for the net carbon uptake models.
Date: September 11, 2013
Creator: Fitzjarrald, David Roy
Partner: UNT Libraries Government Documents Department

Using Snow Fences to Augument Fresh Water Supplies in Shallow Arctic Lakes

Description: This project was funded by the U.S. Department of Energy, National Energy Technology Laboratory (NETL) to address environmental research questions specifically related to Alaska�s oil and gas natural resources development. The focus of this project was on the environmental issues associated with allocation of water resources for construction of ice roads and ice pads. Earlier NETL projects showed that oil and gas exploration activities in the U.S. Arctic require large amounts of water for ice road and ice pad construction. Traditionally, lakes have been the source of freshwater for this purpose. The distinctive hydrological regime of northern lakes, caused by the presence of ice cover and permafrost, exerts influence on lake water availability in winter. Lakes are covered with ice from October to June, and there is often no water recharge of lakes until snowmelt in early June. After snowmelt, water volumes in the lakes decrease throughout the summer, when water loss due to evaporation is considerably greater than water gained from rainfall. This balance switches in August, when air temperature drops, evaporation decreases, and rain (or snow) is more likely to occur. Some of the summer surface storage deficit in the active layer and surface water bodies (lakes, ponds, wetlands) is recharged during this time. However, if the surface storage deficit is not replenished (for example, precipitation in the fall is low and near‐surface soils are dry), lake recharge is directly affected, and water availability for the following winter is reduced. In this study, we used snow fences to augment fresh water supplies in shallow arctic lakes despite unfavorable natural conditions. We implemented snow‐control practices to enhance snowdrift accumulation (greater snow water equivalent), which led to increased meltwater production and an extended melting season that resulted in lake recharge despite low precipitation during the years of the experiment. For ...
Date: March 31, 2013
Creator: Stuefer, Svetlana
Partner: UNT Libraries Government Documents Department