Publications Published in 2010

1. Achieving forest carbon information with higher certainty: A five-part plan. D. James Baker, Gary Richards, Alan Grainger, Patrick Gonzalez, Sandra Brown,Ruth DeFries, Alexander Held, Josef Kellndorfer, Peter Ndunda, Dennis Ojima, Per-Erik Skrovseth, Carlos Souza Jr., Fred Stollem.
   Environmental Science & Policy: 2010
   DOI: 10.1016/j.envsci.2010.03.004
   Notes
   International negotiations on the inclusion of land use activities into an emissions reduction system for the UN Framework Convention on Climate Change (UNFCCC) have been partially hindered by the technical challenges of measuring, reporting, and verifying greenhouse gas (GHG) emissions and the policy issues of leakage, additionality, and permanence. This paper outlines a five-part plan for estimating forest carbon stocks and emissions with the accuracy and certainty needed to support a policy forReducing EmissionsfromDeforestationandforest Degradation, forest conservation, sustainable management of forests, and enhancement of forest carbon stocks (the REDD-plus framework considered at the UNFCCC COP-15) in developing countries. The plan is aimed at UNFCCC non-Annex 1 developing countries, but the principles outlined are also applicable to developed (Annex 1) countries. The parts of the plan are: (1) Expand the number of national forest carbon Measuring, Reporting, and Verification (MRV) systems with a priorty on tropical developing countries; (2) Implement continuous global forest carbon assessments through the network of national systems; (3) Achiev commitments from national space agencies for the necessary satellite data; (4) Establish agreed-on standards and independent verification processes to ensure robust reporting; and (5) Enhance coordination among international and multilateral organizations.
   
   
   
2. Aircraft measurements of vertical profiles of aerosol mixing states. Kerri A. Pratt, Kimberly A. Prather.
   GEOPHYSICAL RESEARCH LETTERS: 2010
   DOI: 10.1029/2009JD013150
   Notes
   To examine the overall impact of aerosols on climate, direct measurements of the size‐resolved mixing states of atmospheric particles are needed as a function of altitude. During the Ice in Clouds Experiment‐Layer Clouds, the recently developed aircraft aerosol time‐of‐flight mass spectrometer directly measured the vertical profiles of size‐resolved single‐particle chemistry in cloud‐free air over Wyoming and northern Colorado. These represent the first aircraft‐based, dual polarity mass spectrometry measurements, allowing a detailed examination of in situ single‐particle mixing state as a function of altitude. Measurement of both positive and negative ions for each individual particle provides the ability to identify the primary particle type/source, such as biomass burning, organic carbon, or soot, and examine the extent of mixing with secondary species, such as ammonium, nitrate, sulfate, and sulfuric acid. For the primary particle cores, biomass burning represented the largest source of submicron particles: ∼33–39% by number from 1 to 7 km. Organic carbon particles were the second most abundant type (maximum of ∼33% by number from 1.2 to 2.0 km) with elemental carbon (soot) particles comprising 14–22% by number from 1 to 7 km. In general, biomass burning, organic carbon, and soot particles were frequently internally mixed with ammonium, nitrate, and sulfate at lower altitudes, switching to sulfate and sulfuric acid mixtures at higher altitudes. Further, the number fraction of externally mixed sulfuric acid particles increased with altitude from 1 to 9%, likely because of cloud processing of SO2. The variance of particle mixing state with altitude significantly changes absorption and hygroscopic properties, and must be taken into account in models calculating aerosol direct and indirect radiative forcings
   
   
   
3. Analysis of aerosol‐cloud interaction from multi‐sensor satellite observations. Lorenzo Costantino, François‐Marie Bréon.
   GEOPHYSICAL RESEARCH LETTERS: 2010
   DOI: 10.1029/2009GL041828
   Notes
   Aerosol interaction with clouds is the main uncertainty for the quantification of the anthropogenic forcing on climate. The first step of the so‐called “aerosol indirect effect” is the change of cloud droplet size distribution when seeded by anthropogenic aerosols. Satellite data provide the density and diversity of observations needed for a statistical estimate of this effect. Numerous such studies have demonstrated the correlation between aerosol load and Cloud Droplet Radius (CDR) and a few have quantified the impact of aerosol on the microphysics. Here, we go one step further by using the profiles from the spaceborne CALIPSO lidar that indicates the respective position of aerosol and cloud layers. The results show that, when aerosol and cloud layers are clearly separated, there is no correlation between aerosol load and CDR. On the other hand, when the lidar profile indicates mixing, there is a strong correlation. We focus on the stratocumulus cloud fields off the coast of Namibia and Angola that are see ed by biomass burning aerosols from Africa. The log‐log slope of CDR and a proxy of the condensation nuclei number are −0.24 in excellent agreement with theoretical estimate. When the vertical profile information is not used, the slope is significantly smaller.
   
   
   
4. California AUAV Air Pollution Profiling Study (CAPPS). Corrigan, CE., MV Ramana, A Zhu, OL Hadley, K Lehmann, V. Ramanathan ; California Energy Commission.
   California Energy Commission, PIER Energy-Related Environmental Research: 2010
   Notes
   Measuring aerosol and gas phase pollutants at the surface level only provides partial information for both climate and air pollution studies. Remote sensing satellites typically provide column integrated measurements (surface to top of atmosphere) and are very limited in their ability to provide resolved vertical profiles. Information on the vertical distribution of these species is important for properly answering questions concerning their impact on regional climate. The California AUAV Air Pollution Profiling Study CAPPS is the first study of its kind in California to collect routine vertical profiles of aerosol, black carbon, and ozone pollutants in conjunction with solar radiation measurements. Moreover, CAPPS was the first study of its kind anywhere to incorporate lightweight autonomous unmanned aerial vehicles (AUAV) in routine atmospheric measurements. The amount of black carbon particulate matter above semi-rural desert and coastal Southern California during April-May of 2008 was between zero and 100 ng/m3 up to 4 km altitude. Measurements during the summer and fall also showed black carbon concentrations below 100 ng/m3 above 2km altitude except during wildfire events in July 2008 when concentrations were as high as 400 ng/m3 above 2 km. The average observed ozone concentrations above NASA Dryden and Vandenberg AFB demonstrated modest variability over the various flights and were roughly twice the background level typically measured over remote surface locations (25-40 ppb) (Vingarzan, 2004). The highest event of ozone concentration was observed in July and corresponded to the highly polluted wildfire events. Regional haze from extensive wildfires in July 2008 throughout California provided the opportunity to perform the first ever direct measurements of atmospheric solar absorption over California using stacked aircraft. The measurements produced estimates of +25.3 W/m2 of forcing in the atmosphere and -31 W/m2 of forcing at the surface (broadband). Considering that smoke blankets large regions of the state for the weeks and months that these fires persist, the effect on climate forcing in California could be substantial.
   
   
   
5. Characterization of the Single Particle Mixing State of Individual Ship Plume Events Measured at the Port of Los Angeles. Andrew P. Ault, Cassandra J. Gaston, Ying Wang, Gerardominguez, Mark H. Thiermes, Kimberly A. Prather.
   Environmental Science & Technology: 2010
   DOI: 10.1021/es902985h
   Notes
   Ship emissions contribute significantly to gaseous and particulate pollution worldwide. To better understand the impact of ship emissions on air quality, measurements of the sizeresolved chemistry of individual particles in ship emissions were made at the Port of Los Angeles using real-time, singleparticle mass spectrometry. Ship plumes were identified through a combination of ship position information and measurements of gases and aerosol particles at a site 500 m from the center of the main shipping channel at the Port of Los Angeles. Single particles containing mixtures of organic carbon, vanadium, and sulfate (OC-V-sulfate) resulted from residual fuel combustion (i.e., bunker fuel),whereashigh quantities of fresh soot particles (when OC-V-sulfate particles were not present) represented distinct markers for plumes from distillate fuel combustion (i.e., diesel fuel) from ships as well as trucks in the port area. OC-V-sulfate particles from residual fuel combustion contained significantly higher levels of s lfate and sulfuric acid than plume particles containing no vanadium. These associations may be due to vanadium (or other metals such as iron) in the fuel catalyzing the oxidation of SO2 to produce sulfate and sulfuric acid on these particles. Enhanced sulfate production on OC-V-sulfate ship emission particles would help explain some of the higher than expected sulfate levels measured in California compared to models based on emissions inventories and typical sulfate production pathways. Understanding the overall impact of ships emissions is critical for controlling regional air quality in the many populated coastal regions of the world.
   
   
   
6. Climate Signal Propagation in Southern California Aquifers. Janet Barco, Terri S. Hogue, Manuela Girotto, Donald R. Kendall, Mario Putti.
   Water Resources Research: 2010
   Notes
   The western United States is marked by limited water resources and a fast-growing population. Increasing climate variability as well as a growing demand on water resources highlights the need for improved understanding of linkages between regional climate, surface water dynamics and groundwater recharge. The current study focuses on the linkages between climate variability and groundwater levels in Calleguas Creek watershed located in southern California. Calleguas Creek groundwater system serves as a critical source of water supply for agricultural and industrial use. Precipitation time series and groundwater levels were analyzed throughout Calleguas Creek groundwater basins for the period 1975-2004. Water level variability was analyzed for over 311 individual wells with a subset of 19 wells selected for further analysis. A correlation matrix was computed to establish well locations (or groups) with similar hydrologic behavior. Prewhitening methods were used to evaluate the effect of time-series autocorrela ion on the test statistics for trend detection using the Mann-Kendall test. Both climate and selected groundwater level (well) data were subjected to frequency analysis using Fast Fourier Transform (FFT). The time series of precipitation, the El Niño–Southern Oscillation (ENSO) index, and well levels were analyzed. A strong persistence was observed in the groundwater level time series, ranging from 66- 99 %. Results suggest the existence of significant periodicities between 2.0 and 7.0 years in both the precipitation and the well level data that are partially coincident with ENSO modes. A decadal oscillation was also observed in the well level data, which partially corresponds with the Pacific Decadal Oscillation (PDO). Assessment of the complex interactions between climate variability and groundwater levels will facilitate improved water resources planning and management in water-stressed regions where marginal changes in hydrologic budgets have large implications.
   
   
   
7. Continued Measurements of Black Carbon in Snow and Rain in the Sierra Nevada Mountains. Corrigan, CE., Hadley, O., Ramanathan, V..
   California Energy Commission, PIER Energy-Related Environmental Research: 2010
   Notes
   Black carbon (BC), a main component of combustion-generated soot, is a strong absorber of sunlight and contributes to climate change. Climate effects related to BC contamination of snow and ice include reduction of surface albedo and increased melting. Contamination occurs largely by wet deposition of BC, which makes it important to quantify the concentration of BC in rain and snowfall. From January through May of 2009, automated rain and snow collectors were deployed to collect falling snow samples at Lassen Volcano National Park and the Central Sierra Snow Laboratory (CSSL), in the Sierra Nevada mountains of Northern California. The collected precipitation was analyzed for BC concentration using a modified thermal-optical analysis method wherein light transmitted through the sample is measured over a broad spectral region as the sample evolves during a prescribed heating protocol. BC and other co-evolving carbonaceous material (most notably charred organics) are distinguished by differences in their light absorption selectivity. The average concentration of BC in snow during the winter of 2009 at CSSL and Lassen were 6.3 (± 4.9) ng BC/g water and 0.9 (± 1.1) ng BC/g water, respectively. The concentrations at CSSL were very similar to the concentration of 6.7 (± 3.1) ng BC/g water reported in 2006 at the same location; however, the concentrations at Lassen were nearly a factor of six lower than in 2006. BC concentrations in ambient air at both locations showed that BC was being removed from the air shortly after the onset of precipitation. The amount of BC found in snow was moderately correlated to the amount of BC existing in the air for the site at CSSL just prior to the onset of the storm, which suggested that a significant proportion of the black carbon in snow at CSSL was scavenged from the air as the snow fell to the ground. The correlation does not rule out the possible contribution of black carbon from long range transport to the BC concentrations in the snow. It is still unclear whether enhanced transport of BC from outside California will have a discernable affect on melt rates, or if local pollutants will overwhelm the signal.
   
   
   
8. Cost Analysis of Impacts of Climate Change on Regional Air Quality. Kuo-Jen Liao, Efthimios Tagaris, Armistead G. Russell, Praveen Amar and Shan He, Kasemsan Manomaiphiboon, Jung-Hun Woo.
   Journal of Air and Waste Management Association: 2010
   DOI: 10.3155/1047-3289.60.2.195
   Notes
   Climate change has been predicted to adversely impact regional air quality with resulting health effects. Here a regional air quality model and a technology analysis tool are used to assess the additional emission reductions required and associated costs to offset impacts of climate change on air quality. Analysis is done for six regions and five major cities in the continental United States. Future climate is taken from a global climate model simulation for 2049–2051 using the Intergovernmental Panel on Climate Change (IPCC) A1B emission scenario, and emission inventories are the same as current ones to assess impacts of climate change alone on air quality and control expenses. On the basis of the IPCC A1B emission scenario and current control technologies, least-cost sets of emission reductions for simultaneously offsetting impacts of climate change on regionally averaged 4th highest daily maximum 8-hr average ozone and yearly averaged PM2.5 (particulate matter [PM] with an aerodynamic diameter less than 2 5 m) for the six regions examined are predicted to range from $36 million (1999$) yr 1 in the Southeast to $5.5 billion yr 1 in the Northeast. However, control costs to offset climate-related pollutant increases in urban areas can be greater than the regional costs because of the l cally exacerbated ozone levels. An annual cost of $4.1 billion is required for offsetting climateinduced air quality impairment in 2049–2051 in the five cities alone. Overall, an annual cost of $9.3 billion is estimated for offsetting climate change impacts on air quality for the six regions and five cities examined. Much of the additional expense is to reduce increased levels of ozone. Additional control costs for offsetting the impacts everywhere in the United States could be larger than the estimates in this study. This study shows that additional emission controls and associated costs for offsetting climate impacts could significantly increase currently estimated control requirements and should be considered in developing con rol strategies for achieving air quality targets in the future.
   
   
   
9. Direct Measurements of the Ozone Formation Potential from Livestock and Poultry Waste Emissions. C O D Y J . H O W A R D ; A N U J K U M A R ; F R A N K M I T L O E H N E R ; K I M B E R L Y S T A C K H O U S E ; P E T E R G . G R E E N ; R O B E R T G . F L O C C H I N I ; M I C H A E L J . K L E E M A N.
   2010
   DOI: 10.1021/es901916b
   Notes
   The global pattern of expanding urban centers and increasing agricultural intensity is leading to more frequent interactions between air pollution emissions from urban and agricultural sources. The confluence of these emissions that traditionally have been separated by hundreds of kilometers is creating new air quality challenges in numerous regions across the United States. An area of particular interest is California’s San Joaquin Valley (SJV), which has an agricultural output higher than many countries, a rapidly expanding human population, and ozone concentrations that are already higher than many dense urban areas. New regulations in the SJV restrict emissions of reactive organic gases (ROGs) from animal sources in an attempt to meet Federal and State ozone standards designed to protect human health. The objective of this work is to directly measure the ozone formation potential (OFP) of agricultural animal plus waste sources in representative urban and rural atmospheres using a transportable “smog” cha ber. Four animal types were examined: beef cattle, dairy cattle, swine, and poultry. Emissions from each animal plus waste type were captured in a 1 m3 Teflon bag, mixed with representative background NOx and ROG concentrations, and then exposed to UV radiation so that ozone formation could be quantified. The emitted ROG composition was also measured so that the theoretical incremental reactivity could be calculated for a variety of atmospheres and directly compared with the measured OFPunder the experimental conditions. The results demonstrate that OFP associated with waste ROG emissions from swine (0.39 ( 0.04 g-O3 per g-ROG), beef cattle (0.51 ( 0.10 g-O3 per g-ROG), and dairy cattle (0.42 ( 0.07 g-O3 per g-ROG) are lower than OFP associated with ROG emissions from gasoline powered light-duty vehicles (LDV) (0.69 ( 0.05 g-O3 per g-ROG). The OFP of ROG emitted from poultry waste (1.35 ( 0.73 g-O3 per g-ROG) is approximately double the LDV OFP. The measured composition of ROG emitted from animal plus waste ources is nine times less reactive than the current regulatory profiles that are based on dated measurements. The new animal waste ROG OFP measurements combined with adjusted animal wasteROGemissions inventory estimates predict that actual ozone production in the SJV from livestock and poultry (5.7 ( 1.3 tons O3 day-1) is 40 ( 10% of the ozone produced by light duty gasoline vehicles (14.3(1.4 tonsO3 day-1) under constant NOx conditions.
   
   
   
10. Dynamics of an emerging disease drive large-scale amphibian population extinctions. Vance T. Vredenburg, Roland A. Knapp, Tate S. Tunstall, Cheryl J. Briggs.
    PNAS: 2010
    DOI: 10.1073/pnas.0914111107
    Notes
    Epidemiological theory generally suggests that pathogens will not cause host extinctions because the pathogen should fade out when the host population is driven below some threshold density. An emerging infectious disease, chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd) is directly linked to the recent extinction or serious decline of hundreds of amphibian species. Despite continued spread of this pathogen into uninfected areas, the dynamics of the host–pathogen interaction remain unknown. We use fine-scale spatiotemporal data to describe (i) the invasion and spread of Bd through three lake basins, each containing multiple populations of the mountain yellow-legged frog, and (ii) the accompanying host–pathogen dynamics. Despite intensive sampling, Bd was not detected on frogs in study basins until just before epidemics began. Following Bd arrival in a basin, the disease spread to neighboring populations at ≈700 m/yr in a wave-like pattern until all populations were infected. Within a population, infection prevalence rapidly reached 100% and infection intensity on individual frogs increased in parallel. Frog mass mortality began only when infection intensity reached a critical threshold and repeatedly led to extinction of populations. Our results indicate that the high growth rate and virulence of Bd allow the nearsimultaneous infection and buildup of high infection intensities in all host individuals; subsequent host population crashes therefore occur before Bd is limited by density-dependent factors. Preventing infection intensities in host populations from reaching this threshold could provide an effective strategy to avoid the extinction of susceptible amphibian species in the wild.