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Funded Projects
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Title
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Principal Investigator (s)
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Topic (s)
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Year Initially Funded
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Year Initially Funded:
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2012
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Topic (s):
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CalNex |
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Investigating Sources and Impacts of Ammonia on PM loading during CalNex
Ammonia (NH3) is the dominant form of reduced nitrogen in the atmosphere and contributes to both the formation of particulate matter (PM) and the deposition of reactive nitrogen to the environment. PM degrades air quality and is one of the most uncertain contributors to global climate forcing. Ammonium aerosol is formed when ammonia reacts with sulfuric nitric acids to form ammonium salts. While ammonia neutralization is not required for sulfate formation, it is critical to the formation of nitrate aerosol. Inorganic PM formation is therefore a complex combination of emissions and thermodynamic formation processes. These processes are not well understood and while previous studies have suggested that ammonia emission controls may be a cost-effective means of reducing PM loading in the U.S., the paucity of measurements of ambient ammonia has limited our examination of this system. In this project we will use an unprecedented suite of in situ measurements of NH3 (as well as inorganic aerosol and related precursors) from ground sites and aircraft during the CalNex field campaign, as well as satellite retrievals of ammonia from the IASI instrument to study PM formation in the Western United States. This project will synthesize these measurements with the GEOS-Chem model to address the following objectives: A. To examine our understanding of ammonia emission sources in California B. To investigate the role of ammonia in PM loading in the Western US. These objectives will be explored through several specific tasks: 1. Use a constrained thermodynamic model to examine whether thermodynamic equilibrium applies to both surface and aircraft observations during CalNex and to investigate the relative role of different ions in inorganic aerosol formation. 2. Investigate whether the GEOS-Chem model reproduces with fidelity the spatial and temporal distribution of observed ammonia. From this, investigate any discrepancies considering both inaccuracies in emission inventories and deficiencies in the description of specific processes. 3. Use the IASI satellite observations to place the in situ CalNex measurements in the larger context of ammonia loading in the Western U.S. through 2010. 4. Use the GEOS-Chem model to assess the contribution of ammonia to PM loading in California, and the Western U.S.
Principal Investigator (s): Colette Heald, MIT
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Year Initially Funded:
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2012
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Topic (s):
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carbon cycle |
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Multi-Scale Characterization of Carbon Flux Dynamics and Biogenic Gas Distribution in the Everglades using Hydrogeophysical Methods
The goal of this project is to conduct research to investigate the spatial and temporal distribution of biogenic gases in the Everglades to determine how scale of measurement and peat type may affect biogenic gas dynamics in subtropical systems. Using hydrogeophysical techniques constrained with a gas flux analyzer, time-lapse measurements will be performed at several support volumes (laboratory and field scale) for different peat samples and locations across the Everglades. The time-lapse data will then be used to develop empirical models to predict forcing mechanisms on biogenic gas releases using statistical tools and time-frequency analysis.
Principal Investigator (s): Xavier Comas (Florida Atlantic University)
Co-PI (s): |
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2012
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Topic (s):
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carbon cycle, ocean circulation |
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Drake Passage as a Test Bed for Large Scale Changes in Southern Ocean Biogeochemistry
Ocean models, atmospheric data, and ocean observations indicate that the Southern Ocean sink for atmospheric CO2 has substantially weakened in the last few decades. The goal of the project is to quantify and understand the spatio-temporal variability in Southern Ocean biogeochemistry using data collected in the Drake Passage measurement program, data collected in other parts of the Southern Ocean, and output from an ocean biogeochemical and ecological model. This study will help to confirm these trends and understand the cause of decreasing CO2 uptake in the Southern Ocean in recent decades. In the proposed study, variability and trends in nutrients and carbon isotopes will be examined at multiple scales and locations in the Drake Passage to understand the processes driving both short-term variability and long-term trends. These trends will be quantitatively compared to those observed in other Southern Ocean locations. The study will employ the Massachusetts Institute of Technology ocean general circulation model with embedded biogeochemistry and ecology, and will reconfigure this model to include the explicit representation of carbon isotopes. Output from hindcast simulations and sensitivity studies will help place the biogeochemical observations into a larger spatiotemporal context, and will help frame our mechanistic understanding of variability and trends.
Principal Investigator (s): Nicole Lovenduski, University of Colorado
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Year Initially Funded:
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2011
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Topic (s):
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CalNex, greenhouse gases |
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Emission Rates for CH4 and N2O in California by Location and Sector Inferred using airborne measurements during the NOAA CalNex Study
The proposed work will produce robust estimates for emission rates of methane and nitrous oxide from California, spatially distributed, disaggregated by major sector or emission process, time resolved during spring and early summer, and rigorously assessed for accuracy. We will use the CalNex data set obtained by the NOAA P-3 aircraft in May and June, 2010. The principal data sets we will use are our own measurements of CO2, CO, CH4 and N2O concentrations, combined with data for CO2, CO, CH4, NOx, NOy, SO2, solvent gases, black carbon, NH4+, and other species measured by NOAA investigators on the P-3 aircraft. Our approach uses a high resolution assimilated meteorological model (WRF) with a Lagrangian Particle Dispersion Model (STILT) to produce a “footprint” (transfer function between surface emission flux and concentration increment at a receptor). We overlay the footprint onto a priori surface flux fields to simulate the measured concentrations of CH4 and N2O at receptor points that cover California in space and time (the P-3 aircraft in CalNex). We will determine the optimal constraints on upwind emission rates by adjusting process-specific emissions from a priori flux inventories, focusing on those in current use by California regulators to guide planning for reductions in Greenhouse Gas emissions (EDGAR, GEIA, and California GHG Inventory, plus process-based emission models DLEM and DNDC). Geostatistical inverse analyses will also be carried out, to derive fluxes independent of a priori fluxes. The work involves close collaboration with more than a half dozen NOAA colleagues involved with CalNex.
Principal Investigator (s): Steven Wofsy, Harvard University
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Year Initially Funded:
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2011
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Topic (s):
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CalNex, aerosols |
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The Impact of Organic Matter and Black Carbon Emissions on Regional Variations in Aerosol Radiative Forcing over California
Regional-scale modeling and CalNex field campaign data will be integrated to assess the impact of organic matter and black carbon on direct, semi-direct, and indirect radiative forcing over California. Particular attention will be given to quantifying how changes in primary particulate and particulate precursor emissions affect oxidant chemistry, PM2.5, and aerosol radiative forcing, since policy makers need to understand the impacts of potential emission mitigation strategies on both air quality and climate. Our analyses of the field data and model predictions will be guided by the following scientific questions: 1) Are current emission inventories of primary particulates, particularly black carbon and organic matter, and particulate precursors consistent with comparisons between observed and simulated aerosol mass and composition? 2) How well does the volatility basis set approach represent secondary organic aerosol evolution in California and what are the relative contribution of anthropogenic, biogenic, and biomass burning sources to organic aerosols in the South Coast Air Basin, the San Joaquin Valley, and the Sacramento Valley? 3) To what extent do aerosols impact aerosol direct and indirect radiative forcing over different geographical regions using a state-of-the-science regional model, and how does the mixing of organic matter components and black carbon with other species affect their optical properties? 4) What are the differences in aerosol radiative forcing resulting from local emissions in California compared with the long-range transport of aerosols? What are the differences in aerosol radiative forcing between anthropogenic and natural emission sources? We will use the chemistry version of the Weather Research and Forecasting (WRF) model that includes representations of the interactions of aerosols, radiation, clouds, and chemistry implemented by PNNL scientists. Recently, two new components have been added to WRF-Chem to help us address the science questions. First, the ‘volatility basis set’ approach has been coupled with the SAPRC 1999 gas-phase photochemical mechanism and the MOSAIC aerosol model in WRF to better represent secondary organic aerosols (SOA). In this approach the current static representation of primary organic aerosol (POA) has been replaced by a dynamic approach in which low volatility organic material evaporates, undergoes multi-generational chemistry and recondenses over varying time and spatial scales to form SOA. In addition, the VBS approach represents SOA formation due to multi-generational chemistry of a complex mixture of thousands of un-identified organic species that are missing in existing inventories. This highly improved representation of SOA is expected to have profound implications on the current understanding of organic aerosols, their mixing state with black carbon, and their relation to aerosol radiative forcing and climate change. Second, physics modules, including those for aerosol and aerosol radiative forcing, from the Community Atmospheric Model 5 (CAM5) global climate model have been ported to WRF. Using the CAM5 and standard WRF parameterizations, we will also be able to compare the strengths and weaknesses of parameterizations employed by global climate models and regional models, using the same modeling framework and emissions.
Principal Investigator (s): Jerome Fast, PNNL
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Year Initially Funded:
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2011
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Topic (s):
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aerosols |
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Resolving the Role of Contact Ice Nucleation on the Earth’s Climate System Using Laboratory and Field Studies
The most recent report of the Intergovernmental Panel on Climate Change (IPCC; Solomon et al., 2007) states that among the most uncertain processes in our understanding of climate change is the interplay between aerosol particles and cloud formation. More recently, this has been shown using direct observations of the Earth’s energy balance by Murphy et al. (2009). Clouds can be composed of liquid water droplets, ice crystals, or mixtures of the two phases. The formation of water droplets is relatively well understood due to formation conditions near room temperature and clouds that can be located at or near ground level. Conversely, ice formation requires temperatures and water vapor contents considerably lower than what is typical found at ground level so that studies at high altitudes or latitudes are required. Because of this, ice formation is the less well understood process and currently limits our ability to determine future climate change. There are several mechanisms by which ice nucleation can take place (Pruppacher and Klett, 1997). The most studied are the deposition of water vapor to a particle surface (‘deposition freezing’) and from within a droplet (‘immersion freezing’). Less studies, and consequently less well understood, is ice nucleation upon the contact of two particles (‘contact freezing’). It is noteworthy that due to current instrumental limitations and experimental complexity recent efforts at parameterizing ice nucleation have attempted to address deposition and immersion but not contact freezing (e.g. DeMott et al., 2010). Recent field studies at mountain-top locations and from research aircraft at high altitudes and latitudes have suggested which particles are most likely to form ice in the atmosphere via the deposition and immersion modes. What are now needed are in-depth studies of the ice nucleation processes, in particular contact nucleation, and these are best conducted in the laboratory using controlled conditions and high precision characterization techniques. We propose a two-part study of contact ice nucleation. We assume the particles that have been suggested as ice nuclei during recent field studies of immersion and deposition nucleation as a starting point for contact freezing: mineral dusts and metallic particles (e.g., DeMott et al., 2003a). Particles such as soot and biological material will also be studied. The first part of this study will be to determine the ice formation conditions of each particle type due to contact freezing. These experiments will utilize a Fourier transform infrared spectrometer and a single particle mass spectrometer which will be used to detect freezing onset conditions and determine if contact nucleation has taken place, respectively. The second part of this study will be to deploy this technique in a field study. The proposed location is a mountaintop site with access to free tropospheric aerosol. As a results we will be able to determine onset conditions and the composition and size of atmospherically relevant contact ice nuclei.
Principal Investigator (s): Daniel Cziczo, MIT
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Year Initially Funded:
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2011
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Topic (s):
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CalNex, aerosols |
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CalNex 2010: Characterizing Organic Aerosol Physical, Chemical, and Hygroscopic Properties using Single Particle Scanning Transmission X-ray Microscopy and Atomic Force Microscopy
Atmospheric aerosols are a complex micro-structured mixture of inorganic and organic components, where organics can represent more than 50% of the aerosol mass depending on location. Understanding and predicting the climate effects due to atmospheric aerosols requires quantitative knowledge of their hygroscopic and chemical properties. The ability of aerosols to absorb water influences their optical and cloud forming properties, ice nuclei formation and transformation, atmospheric lifetime, and chemical reactivity. The presence of organic carbon in aerosols has a complex effect on their physical-chemical and reactive properties that is poorly understood. In particular, there is a lack of robust quantitative measurements on how properties of organic components (such as particle size, morphology, chemical composition, concentration and type of mixing) influence the rate and amount of water uptake on aerosols. The proposed work focuses on microscopic analysis of atmospheric aerosols collected during the CalNex field study in California in 2010. The main goal of the proposed research is to conduct detailed microscopic characterization of the size-dependent elemental and chemical composition, density and hygroscopic properties of organic compounds in aerosol samples collected at the Caltech, Pasadena ground site. Scanning Transmission X-ray Microscopy and Atomic Force Microscopy form a unique combination that will be utilized in this work to measure and quantify these properties on a single particle basis. The proposed work will address the following questions: 1) What chemical/elemental composition and concentration of organic aerosols are representative of the specific location of the CalNex 2010 study? 2) What effect does organic carbon have on aerosol hygroscopic properties and how does it depend on particle size/shape and aerosol micro-structure? 3) What is the chemical nature of organic compounds that exhibit the most substantial effects on their hygroscopic properties? 4) How do the atmospheric processing and subsequent differences in organic aerosol composition and micro-structure affect these properties? The results of this study will provide currently lacking input for closure studies focused on (a) aerosol emission inventories of aerosols, (b) chemical transformation and atmospheric aging of aerosols, (c) correlated elemental/chemical compositions and hygroscopic/ice nucleation properties of aerosols, and (d) determination of the type and concentration of organic compounds. Additionally, we will collaborate with other research groups that deployed instruments for the optical, cloud condensation nuclei and ice nuclei measurements at the Caltech supersite. Combined sets of data will contribute to the CalNex 2010 mission focused on understanding of the chemical composition of organic aerosols, mechanisms of their formation, growth and atmospheric transformations, and their indirect climate effects in California. The results to be obtained from this work are expected to provide invaluable fundamental data for understanding climate and air quality related impacts of organic aerosols at local and regional area of the CalNex 2010 study.
Principal Investigator (s): Alexei Tivanski, University of Iowa; Mary Gilles, LBNL
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Year Initially Funded:
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2011
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Topic (s):
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carbon dioxide |
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Improving CarbonTracker Flux Estimates for North America: A Multi-Species Lagrangian Inversion
The goal of the project is to to better understand and improve the robustness of the North American CO2 budget computed by NOAA’s CarbonTracker by developing a Lagrangian optimization module for CarbonTracker and to perform a set of CO2 and multi-species optimizations. To this end, the project will upgrade the NOAA Air Resources Laboratory’s HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model to compute accurate sampling footprints (influence functions that describe the sensitivity of an air sample to upwind sources and sinks) corresponding to all North American measurements used in CarbonTracker for the period 2007 to 2010. This work will improve the accuracy of CO2 flux estimates for North America at regional and local scales and will represent a significant step toward addressing the scientific and societal need for independent verification of fossil fuel CO2 emissions estimates from inventories. All products and software to be developed by this project (including the footprint library, optimized fluxes, and the upgraded HYSPLIT model) will be made publicly available.
Principal Investigator (s): Arlyn Andrews, NOAA ESRL Global Monitoring Division
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Year Initially Funded:
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2011
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Topic (s):
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carbon dioxide, terrestrial fluxes, modeling, North America |
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North America Carbon Cycle Diagnoses Using Flux and Mixing Ratio Observations, and High-Resolution Regional Transport Modeling
The goal of the project is to improve the understanding of the carbon balance of the terrestrial ecosystems of North America, including understanding of uncertainty and resolution in space and time of these fluxes, leading ultimately to an understanding of the processes governing these fluxes and their variability in space and time. The project will thus undertake the following: 1) maintain collection of CO2 mixing ratio data at 4 AmeriFlux towers; 2) run continental-scale atmospheric inversions at 40 km spatial and weekly temporal resolution using the Weather Research and Forecast model and the Lagrangian Particle Dispersion Model for the time period from 2007-2011 using all available continental CO2 mixing ratio measurements, using CarbonTracker for boundary conditions, and integrating the North American flux tower network into the prior flux estimate; 3) perform a wide range of sensitivity studies on our regional inversion including tests of atmospheric transport, prior fluxes and prior uncertainty, structure of the inverse solution, and large-scale boundary conditions (both meteorological and CO2); 4) better define the uncertainty in the inverse estimates via these sensitivity studies; 5) examine the degree to which the inversion is able to resolve North American CO2 fluxes in space and time; and 6) conduct systematic comparisons to CarbonTracker, including efforts to diagnose the causes of differences by controlling the differences between the two inverse systems.
Principal Investigator (s): Kenneth Davis, Pennsylvania State University
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Year Initially Funded:
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2011
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Topic (s):
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ocean acidification, carbon cycle, biogeochemistry |
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Laboratory Experiments on Ocean Acidification: Effects on Predator Prey Interactions That Drive the Biological Pump
The overall goal of this project is to parameterize how changes in pCO2 levels could alter the carbon export of the world ocean. Specifically, the direct and indirect effects of ocean acidification (OA) will be examined within a simple, controlled predator/prey system using a single prey phytoplankton species (coccolithophore, Pleurochrysis sp.) and a single predator (mesopelagic grazer, Acartia tonsa). The experiments are designed to elucidate both direct effects (i.e. effects of OA on the individual organisms only) and interactive effects (i.e. effects on combined predator/prey system). To meet these goals, a state-of-the-art facility will be constructed with growth chambers that are calibrated and have highly-controlled pH and alkalinity levels. The strength of this work lies in the meticulous calibration and redundant measurements that will be made to ensure that the conditions within the chambers are well described and tightly monitored for Dissolved Inorganic Carbon (DIC) levels. Growth and calcification rates in coccolithophores and the developmental rates, morphological and behavioral effects on copepods will be measured. The Particulate Inorganic Carbon (PIC) and Particulate Organic Carbon (POC) in the algae and the excreted fecal pellets will be monitored for changes in the PIC/POC ratio, a key parameter for modeling feedback mechanisms for rising pCO2 levels. These key experiments will verify closure in the mass balance of PIC, allowing the determination of actual dissolution rates of PIC within the guts of copepod grazers. Data will be disseminated through NOAA's NODC database.
Principal Investigator (s): David Fields, Bigelow Laboratory for Ocean Science
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About Atmospheric Chemistry, Carbon Cycle, & Climate (AC4)
The Climate Program Office (CPO) manages competitive research programs in which NOAA funds high-priority climate science, assessments, decision support research, outreach, education, and capacity-building activities designed to advance our understanding of Earth’s climate system, and to foster the application of this knowledge in risk management and adaptation efforts. CPO-supported research is conducted in regions across the United States, at national and international scales, and globally.
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