ALBERT

Description: For the C4 perennial grasses, Miscanthus  ×  giganteus and Panicum virgatum (switchgrass) to be successful for bioenergy production they must maintain high yields over the long term. Previous studies under the less conducive climate for productivity in N.W. Europe found little or no yield decline in M . ×  giganteus in the long term. This study provides the first analysis of whether yield decline occurs in M . ×  giganteus under United States. Midwest conditions in side-by-side trials with P. virgatum over 8–10 years at seven locations across Illinois. The effect of stand age was determined by using a linear regression model that included effects of weather. Miscanthus  ×  giganteus produced yields more than twice that of P. virgatum averaging 23.4 ± 1.2 Mg ha −1  yr −1 and 10.0 ± 0.9 Mg ha −1  yr −1 , respectively, averaged over 8–10 years. Relationships of yield with precipitation and growing degree days were established and used to estimate yields corrected for the stochastic effects of weather. Across all locations and in both species, yield initially increased until it reached a maximum during the fifth growing season and then declined to a stable, but lower level in the eighth. This pattern was more pronounced in M . ×  giganteus . The mean yields observed over this longer term period of 8–10 years were lower than the yields of the first 5 years. However, this decline was proportionately greater in M . ×  giganteus than in P. virgatum, suggesting a stronger effect of stand age on M . ×  giganteus . Based on the average yield over the period of this study, meeting the United States Renewable Fuel Standard mandate of 60 billion liters of cellulosic ethanol by 2022, would require 6.8 Mha of M . ×  giganteus or 15.8 Mha of P. virgatum . These appear manageable numbers for the United States, given the 16.0 Mha in the farmland Conservation Reserve Program in addition to another 13.0 Mha abandoned from agriculture in the last decade.

Description: [1]  A combined field and laboratory study was conducted to improve our understanding of the chemical and hygroscopic properties of organic compounds in aerosols sampled in the background continental atmosphere. PM 2.5 (particles with aerodynamic diameters smaller than 2.5 µm) aerosols were collected from 24 June to 28 July, 2010 at Storm Peak Laboratory in the Park Range of northwestern Colorado. New particle formation was frequent at Storm Peak Laboratory during this campaign, and the samples were not influenced by regional dust storms. Filter samples were analyzed for organic carbon (OC) and elemental carbon (EC), water soluble OC (WSOC), major inorganic ions, and detailed organic speciation. WSOC was isolated from inorganic ions using solid phase absorbents. Hygroscopic growth factors and cloud condensation nucleus (CCN) activity of the WSOC were measured in the laboratory. Organic compounds comprised the majority (average of 64% with a standard deviation of 9%) of the mass of measured species and WSOC accounted for an average of 89% (with a standard deviation of 21%) of OC mass. Daily samples were composited according to back-trajectories. On average, organic acids, sugars, and sugar alcohols accounted for 12.5 ± 6.2% (average ± standard deviation) of WSOC. Based on the composition of these compounds and that of high molecular weight compounds identified using ultra high resolution mass spectrometry, the organic mass to organic carbon ratio of the WSOC is estimated to be 2.04. The average hygroscopic growth factors at RH = 80% (GF 80 ) were 1.10 ± 0.03 for particles derived from isolated WSOC and 1.27 ± 0.03 for particles derived from the total water-soluble material (WSM). CCN activity followed a similar pattern. The critical diameters at a super-saturation of 0.35% were 0.072 ± 0.009 and 0.094 ± 0.006 µm for particles derived from WSM and isolated WSOC, respectively. These growth factor results compare favorably with estimates from thermodynamic models, which explicitly relate the water activity (RH) to concentration for the total soluble material identified in this study.

Description: [1]  We have measured the bidirectional reflectance of analogs of dry, wet and frozen Martian soils over a wide range of phase angles in the visible spectral range. All samples were produced from two geologic samples: the standard JSC Mars-1 soil simulant and Hawaiian basaltic sand. In a first step, experiments were conducted with the dry samples to investigate the effects of surface texture. Comparisons with results independently obtained by different teams with similar samples showed a satisfying reproducibility of the photometric measurements as well as a noticeable influence of surface textures resulting from different sample preparation procedures. In a second step, water was introduced to produce wet and frozen samples and their photometry investigated. Optical microscope images of the samples provided information about their micro-texture. Liquid water, even in relatively low amount, resulted in the disappearance of the backscattering peak and the appearance of a forward scattering peak whose intensity increases with the amount of water. Specular reflections only appeared when water was present in an amount large enough to allow water to form a film at the surface of the sample. Icy samples showed a wide variability of photometric properties depending on the physical properties of the water ice. We discuss the implications of these measurements in terms of the expected photometric behavior of the Martian surface, from equatorial to circum-polar regions. In particular, we propose some simple photometric criteria to improve the identification of wet and/or icy soils from multiple observations under different geometries.

Description: [1]  We describe a method for determining an optimal centroid–moment tensor solution of an earthquake from a set of static displacements measured using a network of Global Positioning System receivers. Using static displacements observed after the 4 April 2010, M W 7.2 El Mayor-Cucapah, Mexico, earthquake, we perform an iterative inversion to obtain the source mechanism and location, which minimize the least-squares difference between data and synthetics. The efficiency of our algorithm for forward modeling static displacements in a layered elastic medium allows the inversion to be performed in real-time on a single processor without the need for precomputed libraries of excitation kernels; we present simulated real-time results for the El Mayor-Cucapah earthquake. The only a priori information that our inversion scheme needs is a crustal model and approximate source location, so the method proposed here may represent an improvement on existing early warning approaches that rely on foreknowledge of fault locations and geometries.

Description: Marsupials have a functional placenta for a shorter period of time compared to that of eutherian species, and their altricial young reach the teats without any help from the mother. We have monitored the short intrauterine development of one marsupial, the tammar wallaby, with high-resolution ultrasound from reactivation of the 100-cell diapausing blastocyst to birth. The expanding blastocyst could be visualized when it had reached a diameter of 1.5 mm. From at least halfway through pregnancy, there are strong undulating movements of the endometrium that massage the expanding vesicle against the highly secretory endometrial surface. These unique movements possibly enhance exchange of uterine secretions and gases between the mother and embryo. There was a constant rate of development measured ultrasonographically from mid-gestation, regardless of when the blastocyst reactivated. Interestingly climbing movements by the fetus began in utero about 3 days before birth, mimicking those required to climb to the pouch. Scientific Reports 3 doi: 10.1038/srep01458

Description: [1]  The CalNex 2010 (California Research at the Nexus of Air Quality and Climate Change) study was designed to evaluate the chemical composition of air masses over key source regions in California. During May- June 2010, air samples were collected on board a NOAA WP-3D aircraft over the South Coast Air Basin of California (SoCAB) and the Central Valley (CV). This paper analyzes six effective greenhouse gases – chlorodifluoromethane (HCFC-22), 1,1-dichloro-1-fluoroethane (HCFC-141b), 1-chloro-1,1-difluoroethane (HCFC-142b), 2-chloro-1,1,1,2-tetrafluoroethane (HCFC-124), 1,1,1,2-tetrafluoroethane (HFC-134a), and 1,1-difluoroethane (HFC-152a) – providing the most comprehensive characterization of chlorofluorocarbon (CFC)-replacement compound emissions in California. Concentrations of measured HCFCs and HFCs are enhanced greatly throughout the SoCAB and CV, with highest levels observed in the SoCAB: 310 ± 92 pptv for HCFC-22, 30.7 ± 18.6 pptv for HCFC-141b, 22.9 ± 2.0 pptv for HCFC-142b, 4.86 ± 2.56 pptv for HCFC-124, 109 ± 46.4 pptv for HFC-134a, and 91.2 ± 63.9 pptv for HFC-152a. Annual emission rates are estimated for all six compounds in the SoCAB using the measured halocarbon to carbon monoxide (CO) mixing ratios and CO emissions inventories. Emission rates of 3.05 ± 0.70 Gg for HCFC-22, 0.27 ± 0.07 Gg for HCFC-141b, 0.06 ± 0.01 Gg for HCFC-142b, 0.11 ± 0.03 Gg for HCFC-124, 1.89 ± 0.43 Gg for HFC-134a, and 1.94 ± 0.45 Gg for HFC-152b for the year 2010 are calculated for the SoCAB. These emissions are extrapolated from the SoCAB region to the state of California using population data. Results from this study provide a baseline emission rate that will help future studies determine if HCFC and HFC mitigation strategies are successful.

Description: [1]  Several tens of thousands of temperature profiles are used to investigate the thermal evolution of the cold wake of Typhoon Fanapi, 2010. Typhoon Fanapi formed a cold wake in the Western North Pacific Ocean on 18 September characterized by a mixed layer that was 〉2.5 °C cooler than surrounding water, and extending to 〉80 m, twice as deep as the pre-existing mixed layer. The initial cold wake became capped after 4 days as a warm, thin surface layer formed. The thickness of the capped wake, defined as the 26 °C to 27 °C layer, decreased, approaching the background thickness of this layer with an e-folding time of 23 days, almost twice the e-folding lifetime of the Sea Surface Temperature (SST) cold wake (12 days). The wake was advected several hundreds of kilometers from the storm track by a pre-existing mesoscale eddy. The observations reveal new intricacies of cold wake evolution and demonstrate the challenges of describing the thermal structure of the upper ocean using sea surface information alone. © 2013 American Geophysical Union. All rights reserved.

Description: [1]  Decreases in ozone (O 3 ) observed in California's South Coast Air Basin (SoCAB) over the past five decades have resulted from decreases in local emissions of its precursors, nitrogen oxides (NO x  = NO + NO 2 ) and volatile organic compounds (VOCs). Ozone precursors have been characterized in the SoCAB with measurements dating back to 1960. Here, we compile an extensive historical data set using measurements in the SoCAB between 1960 and 2010. Faster rates of decrease have occurred in abundances of VOCs (−7.3 ± 0.7 % year -1 ) than in NO x (−2.6 ± 0.3 % year -1 ), which have resulted in a decrease in VOC/NO x ratio (−4.8 ± 0.9 % year –1 ) over time. Trends in the NO x oxidation products peroxyacetyl nitrate (PAN) and nitric acid (HNO 3 ), measured in the SoCAB since 1973, show changes in ozone production chemistry resulting from changes in precursor emissions. Decreases in abundances of PAN (−9.3 ± 1.1 % year -1 ) and HNO 3 (−3.0 ± 0.8 % year -1 ) reflect trends in VOC and NO x precursors. Enhancement ratios of O 3 to (PAN + HNO 3 ) show no detectable trend in ozone production efficiency, while a positive trend in the oxidized fraction of total reactive nitrogen (+2.2 ± 0.5 % year -1 ) suggests that atmospheric oxidation rates of NO x have increased over time as a result of the emissions changes. Changes in NOx oxidation pathways have increasingly favored production of HNO 3 , a radical termination product associated with quenching the ozone formation cycle.

Description: [1]  The impact of southern California (SoCal) anthropogenic emissions on ozone (O 3 ) in the mountain states in May 2010 is studied using the Sulfur Transport and dEposition Model (STEM). We identified 2-6 major transport events from SoCal to different subregions in the mountain states, with transport times of 0-2 days indicated by trajectories, time-lag correlations and forward/adjoint sensitivities. Based on forward sensitivity analysis, the contributions from SoCal anthropogenic emissions to the monthly-mean daily maximum 8-hour average (MDA8) surface O 3 in the mountain states decrease with distance from SoCal, and they range from 〈1 ppbv (in Wyoming) to 15 ppbv (in western Arizona). These contributions show medium (〉0.6) to strong (〉0.8) positive correlations with the modeled total surface MDA8 O 3 . For the most strongly affected states of Arizona and New Mexico, these contributions have median values of ~3, ~2, ~5, ~15 ppbv when the total surface MDA8 O 3 exceeded thresholds of 60, 65, 70, 75 ppbv, respectively. Surface MDA8 O 3 values in SoCal show strong nonlinear responses to varied magnitudes of perturbation (e.g., ±50% and 100%) in SoCal anthropogenic emissions and weak nonlinear responses in the mountain states. Case studies show that different scales of transport (e.g., trans-Pacific, stratospheric intrusions and inter-state) can be dynamically and chemically coupled and simultaneously affect O 3 in the mountain states when the meteorological conditions are favorable. During some of these strong transport periods, the contributions of SoCal anthropogenic emissions to hourly O 3 in the mountain states can exceed 20 ppbv, close to the magnitude during a summer event reported by Langford et al . [2010]. Satellite observations from the Tropospheric Emission Spectrometer and the Measurements of Pollution in the Troposphere multi-spectral retrievals qualitatively demonstrate large and inter-state scales of transport, respectively. Suggestions are made for future satellite missions to measure O 3 with improved spatial coverage, temporal frequency and near-surface sensitivity to provide better observational constraints on inter-state pollution transport studies.