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Sample records for airborne in-situ observations

  1. Airborne and surface-level in situ observations of wintertime clouds in the Southern Rockies

    NASA Astrophysics Data System (ADS)

    Dorsi, Samuel Winchester

    The phase of cloud water has important impacts on cloud radiative properties, cloud lifetime, and the formation of precipitation. Mixed-phase clouds, or those in which liquid droplets, ice particle and water vapor co-exist, are of particular importance in the Southern Rockies of the United States, where these clouds enhance wintertime mountain precipitation mass and annual water storage in the snowpack. The interaction between multiple water phases within a cloud presents challenges for in situ observation. I describe the existing in situ cloud microphysical instrumentation, and introduce a new instrument for the in situ measurement of total water concentration: the second-generation University of Colorado closed-path tunable-diode laser hygrometer (CLH-2). This compact instrument can be flown within a scientific aircraft under-wing canister and is designed for operation in diverse environmental conditions. During the winter 2010-2011, the CLH-2 was installed on a wind vane at Storm Peak Laboratory (SPL) in the Park Range of Colorado as a part of the Storm Peak Laboratory Cloud Property Validation Experiment (StormVEx) campaign. I apply a new method for determining the bulk mass-dimensional relationship of ice particles from ground-based observations. Despite important difference between airborne and ground-based particle measurements, my parameterization yields particle masses close to those from recent airborne studies that take into account the effect of ice particle shattering on observed number concentrations. Variations in particle density over the course of a storm are suggested by time variations between the observed and parameterized ice water concentrations. Using observations from the Wyoming King Air research aircraft collected during the Colorado Airborne Multi-Phase Cloud Study (CAMPS) in winter 2010-2011, cloud water phase is identified using in situ microphysical measurements. While mixed-phase clouds are identified throughout the study area, the

  2. Synergy of spaceborne remote sensing and airborne in situ observations for the study of Arctic mixed phase clouds at regional and small scales

    NASA Astrophysics Data System (ADS)

    Mioche, G.; Jourdan, O.; Delanoë, J.; Gourbeyre, C.; Dupuy, R.; Guyot, G.; Szczap, F.; Schwarzenboeck, A.

    2015-12-01

    Clouds radiation feedback processes in the Arctic have been identified as one of the greatest sources of uncertainties in the prediction of global climate in GCMs. In particular, mixed phase clouds (MPC) occur very frequently at low-level altitudes in the Arctic, representing between 30% and 50% of the clouds all along the year. However, the characterization of MPC on the whole Arctic region is not yet accurate enough to better understand cloud-radiation interactions. Thus, the knowledge of arctic MPC properties has to be improved. The aim of this study is to characterize MPC properties from regional scale to small scale. This work is based on the synergy of spaceborne active remote sensing (CALIPSO/CloudSat) and airborne in situ observations. We will present results about the time and space variability and vertical distribution of MPC over the entire Arctic region, with a focus on the Svalbard region. The influence of the seasonal cycle as well as surface type (open sea, sea ice, land) on the MPC occurrences will also be investigated. Then, this study will focus on a statistical analysis of MPC clouds properties based on in situ measurements carried out during several airborne campaigns in Svalbard region (14 flights corresponding to 54 vertical profiles). This will provide a detailed characterization of microphysical and optical properties of MPC, discriminating liquid and ice phases. Small scale processes occurring in arctic clouds will be also studied. Finally, accurate profiles of relevant clouds parameters (optical depth, liquid/water fraction, ice crystals morphology, ice and liquid water contents…) will be assessed to contribute to the improvement of clouds representation in global and mesoscale models and to improve airborne and spatial remote sensing retrievals algorithms.

  3. Synergy of spaceborne remote sensing and airborne in situ observations for the study of Arctic mixed phase clouds at regional and small scales

    NASA Astrophysics Data System (ADS)

    Mioche, G.; Jourdan, O.; Delanoë, J.; Gourbeyre, C.; Dupuy, R.; Guyot, G.; Szczap, F.; Schwarzenboeck, A.

    2014-12-01

    Clouds radiation feedback processes in the Arctic have been identified as one of the greatest sources of uncertainties in the prediction of global climate in GCMs. In particular, mixed phase clouds (MPC) occur very frequently at low-level altitudes in the Arctic, representing between 30% and 50% of the clouds all along the year. However, the characterization of MPC on the whole Arctic region is not yet accurate enough to better understand cloud-radiation interactions. Thus, the knowledge of arctic MPC properties has to be improved. The aim of this study is to characterize MPC properties from regional scale to small scale. This work is based on the synergy of spaceborne active remote sensing (CALIPSO/CloudSat) and airborne in situ observations. We will present results about the time and space variability and vertical distribution of MPC over the entire Arctic region, with a focus on the Svalbard region. The influence of the seasonal cycle as well as surface type (open sea, sea ice, land) on the MPC occurrences will also be investigated. Then, this study will focus on a statistical analysis of MPC clouds properties based on in situ measurements carried out during several airborne campaigns in Svalbard region (14 flights corresponding to 54 vertical profiles). This will provide a detailed characterization of microphysical and optical properties of MPC, discriminating liquid and ice phases. Small scale processes occurring in arctic clouds will be also studied. Finally, accurate profiles of relevant clouds parameters (optical depth, liquid/water fraction, ice crystals morphology, ice and liquid water contents…) will be assessed to contribute to the improvement of clouds representation in global and mesoscale models and to improve airborne and spatial remote sensing retrievals algorithms.

  4. Fault and anthropogenic processes in central California constrained by satellite and airborne InSAR and in-situ observations

    NASA Astrophysics Data System (ADS)

    Liu, Zhen; Lundgren, Paul

    2016-07-01

    , but are subject to severe decorrelation. The L-band ALOS and UAVSAR SAR sensors provide improved coherence compared to the shorter wavelength radar data. Joint analysis of UAVSAR and ALOS interferometry measurements show clear variability in deformation along the fault strike, suggesting variable fault creep and locking at depth and along strike. Modeling selected fault transects reveals a distinct change in surface creep and shallow slip deficit from the central creeping section towards the Parkfield transition. In addition to fault creep, the L-band ALOS, and especially ALOS-2 ScanSAR interferometry, show large-scale ground subsidence in the SJV due to over-exploitation of groundwater. Groundwater related deformation is spatially and temporally variable and is composed of both recoverable elastic and non-recoverable inelastic components. InSAR time series are compared to GPS and well-water hydraulic head in-situ time series to understand water storage processes and mass loading changes. We are currently developing poroelastic finite element method models to assess the influence of anthropogenic processes on surface deformation and fault mechanics. Ongoing work is to better constrain both tectonic and non-tectonic processes and understand their interaction and implication for regional earthquake hazard.

  5. Combined MIPAS (airborne/satellite), CALIPSO and in situ study on large potential NAT particles observed in early Arctic winter stratosphere in December 2011

    NASA Astrophysics Data System (ADS)

    Woiwode, Wolfgang; Höpfner, Michael; Pitts, Michael; Poole, Lamont; Oelhaf, Hermann; Molleker, Sergej; Borrmann, Stephan; Ebersoldt, Andreas; Frey, Wiebke; Gulde, Thomas; Maucher, Guido; Piesch, Christof; Sartorius, Christian; Orphal, Johannes

    2015-04-01

    The understanding of the characteristics of large HNO3-containing particles (potential 'NAT-rocks') involved in vertical redistribution of HNO3 in the polar winter stratosphere is limited due to the difficult accessibility of these particles by observations. While robust polar stratospheric cloud (PSC) classification schemes exist for observations by the space-borne lidar aboard CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) as well as for the passive mid-infrared limb observations by MIPAS (Michelson Interferometer for Passive Atmospheric Sounding), these observations are hardly exploited for the detection of large (diameter >10 μm) NAT particles. This is due to the facts that these particles have low overall number densities, resulting in weak detectable signatures, and that the physical characteristics of these particles (i.e. shape, morphology, HNO3-content and optical characteristics) are uncertain. We investigate collocated and complementary observations of a low-density potential large NAT particle field by the space-borne instruments CALIPSO and MIPAS-ENVISAT as well as the airborne observations by the limb-sounder MIPAS-STR and the in situ particle probe FSSP-100 (Forward Scattering Spectrometer Probe 100) aboard the high-altitude aircraft Geophysica. The observations aboard the Geophysica on 11 December 2011 associated to ESSenCe (ESa Sounder Campaign 2011) provided us the unique opportunity to study in detail the lower boundary region of a PSC where large potential NAT particles (>20 μm in diameter) were detected in situ. We analyse the ambient temperatures and gas-phase composition (HNO3 and H2O), the signatures of the observed particles in the CALIPSO and MIPAS observations, the HNO3-content of these particles suggested by the FSSP-100 and MIPAS-STR observations, and focus on the spectral fingerprint of these particles in the MIPAS-STR observations. While the spectral characterisation of the observed particles is subject

  6. Investigation of Arctic mixed-phase clouds by combining airborne remote sensing and in situ observations during VERDI, RACEPAC and ACLOUD

    NASA Astrophysics Data System (ADS)

    Ehrlich, André; Bierwirth, Eike; Borrmann, Stephan; Crewell, Susanne; Herber, Andreas; Hoor, Peter; Jourdan, Olivier; Krämer, Martina; Lüpkes, Christof; Mertes, Stephan; Neuber, Roland; Petzold, Andreas; Schnaiter, Martin; Schneider, Johannes; Weigel, Ralf; Weinzierl, Bernadett; Wendisch, Manfred

    2016-04-01

    To improve our understanding of Arctic mixed-phase clouds a series of airborne research campaigns has been initiated by a collaboration of German research institutes. Clouds in areas dominated by a close sea-ice cover were observed during the research campaign Vertical distribution of ice in Arctic mixed-phase clouds (VERDI, April/May 2012) and the Radiation-Aerosol-Cloud Experiment in the Arctic Circle (RACEPAC, April/May 2014) which both were based in Inuvik, Canada. The aircraft (Polar 5 & 6, Basler BT-67) operated by the Alfred Wegener Institute for Polar and Marine Research, Germany did cover a wide area above the Canadian Beaufort with in total 149 flight hours (62h during VERDI, 87h during RACEPAC). For May/June 2017 a third campaign ACLOUD (Arctic Clouds - Characterization of Ice, aerosol Particles and Energy fluxes) with base in Svalbard is planned within the Transregional Collaborative Research Centre TR 172 ArctiC Amplification: Climate Relevant Atmospheric and SurfaCe Processes, and Feedback Mechanisms (AC)3 to investigate Arctic clouds in the transition zone between open ocean and sea ice. The aim of all campaigns is to combine remote sensing and in-situ cloud, aerosol and trace gas measurements to investigate interactions between radiation, cloud and aerosol particles. While during VERDI remote sensing and in-situ measurements were performed by one aircraft subsequently, for RACEPAC and ACLOUD two identical aircraft are coordinated at different altitudes to horizontally collocate both remote sensing and in-situ measurements. The campaign showed that in this way radiative and microphysical processes in the clouds can by studied more reliably and remote sensing methods can be validated efficiently. Here we will illustrate the scientific strategy of the projects including the progress in instrumentation. Differences in the general synoptic and sea ice situation and related changes in cloud properties at the different locations and seasons will be

  7. Decadal changes in ozone and precursor emissions in the Los Angeles California region using in-situ airborne and ground-based field observations, roadside monitoring data, and surface network measurements

    NASA Astrophysics Data System (ADS)

    Pollack, I. B.; Ryerson, T. B.; Trainer, M.; Atlas, E. L.; Blake, D. R.; Flynn, J. H.; Frost, G. J.; Grossberg, N.; Harley, R. A.; Holloway, J. S.; Lefer, B. L.; Lueb, R.; Parrish, D. D.; Peischl, J.

    2011-12-01

    In-situ observations from the Photochemical Assessment Monitoring Stations (PAMS) and the California Air Resources Board (CARB) surface network show decreases in ozone (O3), nitrogen oxide (NOx=NO+NO2), carbon monoxide (CO), and select volatile organic compounds (VOCs) in California's South Coast Air Basin (SoCAB). Decreases in CO, NOx, and VOCs reflect changes, such as improved catalytic converters and reformulated fuels etc., that have been implemented in response to increasingly strict emissions standards placed upon on-road vehicles in the state of California. Here, we compare changes in emissions ratios of NOx and VOCs to CO determined from surface network data collected since 1994 to changes in emissions ratios from biennial roadside studies conducted in west Los Angeles since 1999 and airborne and ground-based measurements from three independent field campaigns conducted in California in 2002, 2008, and 2010. Using the more extensive in-situ surface network data set, we show that decreasing ozone is positively correlated with decreasing abundances of NOx and VOCs and with decreasing VOC/NOx ratio over time. The changes observed from 1994 to present suggest that reductions in both NOx and VOCs and the VOC/NOx ratio over the years have been effective in reducing ozone in the SoCAB.

  8. Microphysical properties of cirrus clouds between 75°N and 25°S derived from extensive airborne in-situ observations

    NASA Astrophysics Data System (ADS)

    Krämer, Martina

    2016-04-01

    Numerous airborne field campaigns were performed in the last decades to record cirrus clouds microphysical properties. Beside the understanding of the processes of cirrus formation and evolution, an additional motivation for those studies is to provide a database to evaluate the representation of cirrus clouds in global climate models. This is of importance for an improved certainty of climate predictions, which are affected by the poor understanding of the microphysical processes of ice clouds (IPCC, 2013). To this end, the observations should ideally cover the complete respective parameter range and not be influenced by instrumental artifacts. However, due to the difficulties in measuring cirrus properties on fast-flying, high-altitude aircraft, some issues with respect to the measurements %evolved have arisen. In particular, concerns about the relative humidity in and around cirrus clouds and the ice crystal number concentrations were under discussion. Too high ice supersaturations as well as ice number concentrations were often reported. These issues have made more challenging the goal of compiling a large database using data from a suite of different instruments that were used on different campaigns. In this study, we have have addressed these challenges and compiled a large data set of cirrus clouds, sampled during eighteen field campaigns between 75°N and 25°S, representing measurements fulfilling the above mentioned requirements. The most recent campaigns were performed in 2014; namely, the ATTREX campaign with the research aircraft Global Hawk and the ML-CIRRUS and ACRIDICON campaigns with HALO. % The observations include ice water content (IWC: 130 hours of observations), ice crystal numbers (N_ice: 83 hours), ice crystal mean mass size (Rice: 83 hours) and relative humidity (RH_ice) in- and outside of cirrus clouds (78 and 140 hours). % We will present the parameters as PDFs versus temperature and derive medians and core ranges (including the most

  9. Using in situ airborne measurements to evaluate three cloud phase products derived from CALIPSO

    NASA Astrophysics Data System (ADS)

    Cesana, G.; Chepfer, H.; Winker, D.; Getzewich, B.; Cai, X.; Jourdan, O.; Mioche, G.; Okamoto, H.; Hagihara, Y.; Noel, V.; Reverdy, M.

    2016-05-01

    We compare the cloud detection and cloud phase determination of three independent climatologies based on Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) to airborne in situ measurements. Our analysis of the cloud detection shows that the differences between the satellite and in situ measurements mainly arise from three factors. First, averaging CALIPSO Level l data along track before cloud detection increases the estimate of high- and low-level cloud fractions. Second, the vertical averaging of Level 1 data before cloud detection tends to artificially increase the cloud vertical extent. Third, the differences in classification of fully attenuated pixels among the CALIPSO climatologies lead to differences in the low-level Arctic cloud fractions. In another section, we compare the cloudy pixels detected by colocated in situ and satellite observations to study the cloud phase determination. At midlatitudes, retrievals of homogeneous high ice clouds by CALIPSO data sets are very robust (more than 94.6% of agreement with in situ). In the Arctic, where the cloud phase vertical variability is larger within a 480 m pixel, all climatologies show disagreements with the in situ measurements and CALIPSO-General Circulation Models-Oriented Cloud Product (GOCCP) report significant undefined-phase clouds, which likely correspond to mixed-phase clouds. In all CALIPSO products, the phase determination is dominated by the cloud top phase. Finally, we use global statistics to demonstrate that main differences between the CALIPSO cloud phase products stem from the cloud detection (horizontal averaging, fully attenuated pixels) rather than the cloud phase determination procedures.

  10. Utilizing The Synergy of Airborne Backscatter Lidar and In-Situ Measurements for Evaluating CALIPSO

    NASA Astrophysics Data System (ADS)

    Tsekeri, Alexandra; Amiridis, Vassilis; Marenco, Franco; Marinou, Eleni; Rosenberg, Phil; Solomos, Stavros; Trembath, Jamie; Allan, James; Bacak, Asan; Nenes, Athanasios

    2016-06-01

    Airborne campaigns dedicated to satellite validation are crucial for the effective global aerosol monitoring. CALIPSO is currently the only active remote sensing satellite mission, acquiring the vertical profiles of the aerosol backscatter and extinction coefficients. Here we present a method for CALIPSO evaluation from combining lidar and in-situ airborne measurements. The limitations of the method have to do mainly with the in-situ instrumentation capabilities and the hydration modelling. We also discuss the future implementation of our method in the ICE-D campaign (Cape Verde, August 2015).

  11. In situ observations of the atmospheres of terrestrial planetary bodies

    NASA Astrophysics Data System (ADS)

    Harri, Ari-Matti

    2005-11-01

    well as Summary, address the highly successful determination of the Titan atmospheric pressure profile. Publication 8 combines in situ observations and simulations by analyzing Mars Pathfinder measurements with the help of a Martian mesoscale atmospheric model. Finally, in Publication 9 the effect of airborne dust and CO 2 on the radiative transfer in the Martian atmosphere is assessed and a new radiative transfer paramerization scheme for the mesoscale model is introduced.

  12. Integrated Airborne and In-Situ Measurements over Land-Fast Ice near Barrow, AK.

    NASA Astrophysics Data System (ADS)

    Brozena, J. M.; Gardner, J. M.; Liang, R.; Ball, D.; Richter-Menge, J.; Claffey, K. J.; Abelev, A.; Hebert, D. A.; Jones, K.

    2014-12-01

    During March of 2014, the Naval Research Laboratory and the Cold Regions Research and Engineering Laboratory collected an integrated set of airborne and in-situ measurements over two areas of floating, but land-fast ice near the coast of Barrow, AK. The near-shore site was just north of Point Barrow, and the "offshore" site was ~ 20 km east of Point Barrow. The in-situ data provided ground-truth for airborne measurements from a scanning LiDAR (Riegl Q 560i), digital photogrammetry (Applanix DSS-439) and a snow radar procured from the Center for Remote Sensing of Ice Sheets of the University of Kansas. The objective of the survey was to aid our understanding of the use of the airborne data to calibrate/validate Cryosat-2 data. Sampling size or "footprint" plays a critical role in the attempt to compare in-situ measurements with airborne (or satellite) measurements. Thus the in-situ data were arranged to minimize aliasing. Ground measurements were collected along transects at both sites consisting of a 2 km long profile of snow depth and ice thickness measurements with periodic boreholes. A 60 m x 400 m swath of snow depth measurements was centered on this profile. Airborne data were collected on five overflights of the two transect areas. The LiDAR measured total freeboard (ice + snow) referenced to leads in the ice, and produced swaths 200-300 m wide. The radar measured snow thickness. The freeboard and snow thickness measurements are used to estimate ice thickness via isostasy and density estimates. The central swath of in situ snow depth data allows examination of the effects of cross-track variations considering the relatively large footprint of the snow radar. Assuming a smooth, flat surface the radar range resolution in air is < 4 cm, but the along-track sampling distance is ~ 3 m after unfocussed SAR processing. The width of the footprint varies from ~ 9 m up to about 40 m (beam-limited) for uneven surfaces. However, the radar could not resolve snow thickness

  13. Analyses of in-situ airborne volcanic ash from the February 2000 eruption of Hekla Volcano, Iceland

    NASA Astrophysics Data System (ADS)

    Pieri, D.; Ma, C.; Simpson, J. J.; Hufford, G.; Grindle, T.; Grove, C.

    2002-08-01

    A McDonnell-Douglas DC-8 NASA research aircraft inadvertently flew into an airborne volcanic ash plume from the 26 February 2000 eruption of Hekla Volcano. Filter samples from the aircraft were compared with ``normal use'' and ``pristine clean'' filters using SEM, energy-dispersive x-ray spectrometer, and Nicolet FTIR spectrophotometer analyses. These analyses confirm that the DC-8 encountered airborne volcanic ash from Hekla Volcano. This result is supported by independent onboard heated aerosol observations at the time of the encounter. The analyses further demonstrate the ambiguous nature of the dual band thermal IR (``split window'') method for detecting volcanic ash from the point of view of aviation safety. They also highlight the utility of in situ aircraft filter-based observations of volcanic aerosols for scientific purposes.

  14. Integrated Airborne and In-Situ Measurements Over Land-Fast Ice Near Barrow, AK.

    NASA Astrophysics Data System (ADS)

    Gardner, J. M.; Brozena, J. M.; Richter-Menge, J.; Abelev, A.; Liang, R.; Ball, D.; Claffey, K. J.; Hebert, D. A.; Jones, K.

    2015-12-01

    The Naval Research Laboratory has collected two field seasons of integrated airborne and in-situ measurements over multiple sites of floating, but land-fast ice north of Barrow, AK. During the first season in March of 2014 the Cold Regions Research and Engineering Laboratory led the on-ice group including NRL personnel and Naval Academy midshipmen. The second season (March 2015) included only NRL scientists and midshipmen. The in-situ data provided ground-truth for airborne measurements from a scanning LiDAR (Riegl Q 560i), digital photogrammetry (Applanix DSS-439), a low-frequency SAR (P-band in 2014 and P and L bands in 2015) and a snow/Ku radar procured from the Center for Remote Sensing of Ice Sheets of the University of Kansas. The CReSIS radar was updated in 2015 to integrate the snow and Ku radars into a single continuous chirp, thus improving resolution. The objective of the survey was to aid our understanding of the use of the airborne data to calibrate/validate Cryosat-2 data. Sampling size or "footprint" plays a critical role in the attempt to compare in-situ measurements with airborne (or satellite) measurements. Thus the in-situ data were arranged to minimize aliasing. Ground measurements were collected along transects a sites generally consisting of a 2 km long profile of Magnaprobe and EM31 measurements with periodic boreholes. A 60 m x 400 m swath of Magnaprobe measurements was centered on this profile. Airborne data were collected on multiple overflights of the transect areas. The LiDAR measured total freeboard (ice + snow) referenced to leads in the ice, and produced swaths 200-300 m wide. The SAR imaged the ice beneath the snow and the snow/Ku radar measured snow thickness. The freeboard measurements and snow thickness are used to estimate ice thickness via isostasy and density estimates. Comparisons and processing methodology will be shown. The results of this ground-truth experiment will inform our analysis of grids of airborne data collected

  15. In Situ Airborne Measurement of Formaldehyde with a New Laser Induced Fluorescence Instrument

    NASA Astrophysics Data System (ADS)

    Arkinson, H.; Hanisco, T. F.; Cazorla, M.; Fried, A.; Walega, J.

    2012-12-01

    Formaldehyde (HCHO) is a highly reactive and ubiquitous compound in the atmosphere that originates from primary emissions and secondary formation by photochemical oxidation of volatile organic compounds. HCHO is an important precursor to the formation of ozone and an ideal tracer for the transport of boundary layer pollutants to higher altitudes. In situ measurements of HCHO are needed to improve understanding of convective transport mechanisms and the effects of lofted pollutants on ozone production and cloud microphysics in the upper troposphere. The Deep Convective Clouds and Chemistry Project (DC3) field campaign addressed the effects of deep, midlatitude continental convective clouds on the upper troposphere by examining vertical transport of fresh emissions and water aloft and by characterizing subsequent changes in composition and chemistry. Observations targeting convective storms were conducted over Colorado, Alabama, and Texas and Oklahoma. We present measurements of the In Situ Airborne Formaldehyde instrument (ISAF), which uses laser induced fluorescence to achieve the high sensitivity and fast time response required to detect low concentrations in the upper troposphere and capture the fine structure characteristic of convective storm outflow. Preliminary results from DC3 indicate that the ISAF is able to resolve concentrations ranging from under 35 ppt to over 35 ppb, spanning three orders of magnitude, in less than a few minutes. Frequent, abrupt changes in HCHO captured by the ISAF are corroborated by similar patterns observed by simultaneous trace gas and aerosol measurements. Primary HCHO emissions are apparent in cases when the DC-8 flew over combustion sources or biomass burning, and secondary HCHO formation is suggested by observations of enhanced HCHO concurrent with other elevated hydrocarbons. Vertical transport of HCHO is indicated by measurements of over 6 ppb from outflow in the upper troposphere. The DC-8 payload also included the

  16. Column Closure Studies of Lower Tropospheric Aerosol and Water Vapor During ACE-Asia Using Airborne Sunphotometer, Airborne In-Situ and Ship-Based Lidar Measurements

    NASA Technical Reports Server (NTRS)

    Schmid, B.; Hegg, A.; Wang, J.; Bates, D.; Redemann, J.; Russells, P. B.; Livingston, J. M.; Jonsson, H. H.; Welton, E. J.; Seinfield, J. H.

    2003-01-01

    We assess the consistency (closure) between solar beam attenuation by aerosols and water vapor measured by airborne sunphotometry and derived from airborne in-situ, and ship-based lidar measurements during the April 2001 Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia). The airborne data presented here were obtained aboard the Twin Otter aircraft. Comparing aerosol extinction o(550 nm) from four different techniques shows good agreement for the vertical distribution of aerosol layers. However, the level of agreement in absolute magnitude of the derived aerosol extinction varied among the aerosol layers sampled. The sigma(550 nm) computed from airborne in-situ size distribution and composition measurements shows good agreement with airborne sunphotometry in the marine boundary layer but is considerably lower in layers dominated by dust if the particles are assumed to be spherical. The sigma(550 nm) from airborne in-situ scattering and absorption measurements are about approx. 13% lower than those obtained from airborne sunphotometry during 14 vertical profiles. Combining lidar and the airborne sunphotometer measurements reveals the prevalence of dust layers at altitudes up to 10 km with layer aerosol optical depth (from 3.5 to 10 km altitude) of approx. 0.1 to 0.2 (500 nm) and extinction-to-backscatter ratios of 59-71 sr (523 nm). The airborne sunphotometer aboard the Twin Otter reveals a relatively dry atmosphere during ACE- Asia with all water vapor columns less than 1.5 cm and water vapor densities w less than 12 g/cu m. Comparing layer water vapor amounts and w from the airborne sunphotometer to the same quantities measured with aircraft in-situ sensors leads to a high correlation (r(sup 3)=0.96) but the sunphotometer tends to underestimate w by 7%.

  17. A Transport Analysis of In Situ Airborne Ozone Measurements from the 2011 DISCOVER-AQ Campaign

    NASA Astrophysics Data System (ADS)

    Arkinson, H. L.; Brent, L. C.; He, H.; Loughner, C.; Stehr, J. W.; Weinheimer, A. J.; Dickerson, R. R.

    2013-12-01

    Baltimore and Washington are currently designated as nonattainment areas with respect to the 2008 EPA National Ambient Air Quality Standard (NAAQS) for 8-hour Ozone (O3). Tropospheric O3 is the dominant component of summertime photochemical smog, and at high levels, has deleterious effects on human health, ecosystems, and materials. The University of Maryland (UMD) Regional Atmospheric Measurement Modeling and Prediction Program (RAMMPP) strives to improve understanding of air quality in the Mid-Atlantic States and to elucidate contributions of pollutants such as O3 from regional transport versus local sources through a combination of modeling and in situ measurements. The NASA Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) project investigates the connection between column measurements and surface conditions to explore the potential of remote sensing observations in diagnosing air quality at ground level where pollutants can affect human health. During the 2011 DISCOVER-AQ field campaign, in situ airborne measurements of trace gases and aerosols were performed along the Interstate 95 corridor between Baltimore and Washington from the NASA P3B aircraft. To augment this data and provide regional context, measurements of trace gases and aerosols were also performed by the RAMMPP Cessna 402B aircraft over nearby airports in Maryland and Virginia. This work presents an analysis of O3 measurements made by the Ultraviolet (UV) Photometric Ambient O3 Analyzer on the RAMMPP Cessna 402B and by the NCAR 4-Channel Chemiluminescence instrument on the NASA P3B. In this analysis, spatial and temporal patterns of O3 data are examined within the context of forward and backward trajectories calculated from 12-km North American Mesoscale (NAM) meteorological data using the NOAA Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) Model and from a high resolution Weather Research and

  18. Aspects regarding vertical distribution of greenhouse gases resulted from in situ airborne measurements

    NASA Astrophysics Data System (ADS)

    Boscornea, Andreea; Sorin Vajaiac, Nicolae; Ardelean, Magdalena; Benciu, Silviu Stefan

    2016-04-01

    In the last decades the air quality, as well as other components of the environment, has been severely affected by uncontrolled emissions of gases - most known as greenhouse gases (GHG). The main role of GHG is given by the direct influence on the Earth's radiative budget, through Sun light scattering and indirectly by participating in cloud formation. Aldo, many efforts were made for reducing the high levels of these pollutants, e.g., International Panel on Climate Change (IPCC) initiatives, Montreal Protocol, etc., this issue is still open. In this context, this study aims to present several aspects regarding the vertical distribution in the lower atmosphere of some greenhouse gases: water vapours, CO, CO2 and methane. Bucharest and its metropolitan area is one of the most polluted regions of Romania due to high traffic. For assessing the air quality of this area, in situ measurements of water vapours, CO, CO2 and CH4 were performed using a Britten Norman Islander BN2 aircraft equipped with a Picarro gas analyser, model G2401-mc, able to provide precised, continuous and accurate data in real time. This configuration consisting in aircraft and airborne instruments was tested for the first time in Romania. For accomplishing the objectives of the measurement campaign, there were proposed several flight strategies which included vertical and horizontal soundings from 105 m to 3300 m and vice-versa around Clinceni area (20 km West of Bucharest). During 5 days (25.08.2015 - 31.08.2015) were performed 7 flights comprising 10h 18min research flight hours. The measured concentrations of GHS ranged between 0.18 - 2.2 ppm for water vapours with an average maximum value of 1.7 ppm, 0.04 - 0.53 ppm for CO with an average maximum value of 0.21 ppm, 377 - 437.5 ppm for CO2 with an average maximum value of 397 ppm and 1.7 - 6.1 ppm for CH4 with an average maximum value of 2.195 ppm. It was noticed that measured concentrations of GHG are decreasing for high values of sounding

  19. Studying the vertical aerosol extinction coefficient by comparing in situ airborne data and elastic backscatter lidar

    NASA Astrophysics Data System (ADS)

    Rosati, Bernadette; Herrmann, Erik; Bucci, Silvia; Fierli, Federico; Cairo, Francesco; Gysel, Martin; Tillmann, Ralf; Größ, Johannes; Gobbi, Gian Paolo; Di Liberto, Luca; Di Donfrancesco, Guido; Wiedensohler, Alfred; Weingartner, Ernest; Virtanen, Annele; Mentel, Thomas F.; Baltensperger, Urs

    2016-04-01

    Vertical profiles of aerosol particle optical properties were explored in a case study near the San Pietro Capofiume (SPC) ground station during the PEGASOS Po Valley campaign in the summer of 2012. A Zeppelin NT airship was employed to investigate the effect of the dynamics of the planetary boundary layer at altitudes between ˜ 50 and 800 m above ground. Determined properties included the aerosol particle size distribution, the hygroscopic growth factor, the effective index of refraction and the light absorption coefficient. The first three parameters were used to retrieve the light scattering coefficient. Simultaneously, direct measurements of both the scattering and absorption coefficient were carried out at the SPC ground station. Additionally, a single wavelength polarization diversity elastic lidar system provided estimates of aerosol extinction coefficients using the Klett method to accomplish the inversion of the signal, for a vertically resolved comparison between in situ and remote-sensing results. Note, however, that the comparison was for the most part done in the altitude range where the overlap function is incomplete and accordingly uncertainties are larger. First, the airborne results at low altitudes were validated with the ground measurements. Agreement within approximately ±25 and ±20 % was found for the dry scattering and absorption coefficient, respectively. The single scattering albedo, ranged between 0.83 and 0.95, indicating the importance of the absorbing particles in the Po Valley region. A clear layering of the atmosphere was observed during the beginning of the flight (until ˜ 10:00 LT - local time) before the mixing layer (ML) was fully developed. Highest extinction coefficients were found at low altitudes, in the new ML, while values in the residual layer, which could be probed at the beginning of the flight at elevated altitudes, were lower. At the end of the flight (after ˜ 12:00 LT) the ML was fully developed, resulting in

  20. Airborne In Situ and Ground-based Polarimetric Radar Measurements of Tropical Convection in Support of CRYSTAL-FACE

    NASA Technical Reports Server (NTRS)

    Poellot, Michael R.; Kucera, Paul A.

    2004-01-01

    This report describes the work performed by the University of North Dakota (UND) under NASA Grant NAG5-11509, titled Airborne In Situ and Ground-based Polarimetric Radar Measurements of Tropical Convection in Support of CRYSTAL-FACE. This work focused on the collection of data by two key platforms: the UND Citation II research aircraft and the NASA NPOL radar system. The CRYSTAL-FACE (C-F) mission addresses several key issues from the NASA Earth System Enterprise, including the variability of water in the atmosphere, the forcing provided by tropical cirrus and the response of the Earth system to this forcing. In situ measurements and radar observations of tropical convection, cirrus clouds and their environment are core elements of C-F. One of the primary issues that C-F is addressing is the relationship of tropical cirrus anvils to precipitating deep convection. The in situ measurements from C-F are being used to validate remote sensing of Earth-Atmosphere properties, increase our knowledge of upper tropospheric water vapor and its distribution, and increase our knowledge of tropical cirrus cloud morphology and composition. Radar measurements, especially polarimetric diversity observations available fiom the NASA NPOL radar, are providing essential information about the initiation, modulation, and dissipation of convective cores and the generation of associated anvils in tropical convection. Specifically, NPOL radar measurements contain information about convective intensity and its vertical structure for comparison with thermodynamic and kinematic environmental measurements observed from soundings. Because of the polarimetric diversity of MOL, statistics on bulk microphysical properties can be retrieved and compared to the other characteristics of convection and associated cirrus anvils. In summary, the central objectives of this proposal were to deploy the UND Citation research aircraft as an in situ sensing platform for this mission and to provide collaborative

  1. Reconciling In Situ Foliar Nitrogen and Vegetation Structure Measurements with Airborne Imagery Across Ecosystems

    NASA Astrophysics Data System (ADS)

    Flagg, C.

    2015-12-01

    Over the next 30 years the National Ecological Observatory Network (NEON) will monitor environmental and ecological change throughout North America. NEON will provide a suite of standardized data from several ecological topics of interest, including net primary productivity and nutrient cycling, from 60+ sites across 20 eco-climatic domains when fully operational in 2017. The breadth of sampling includes ground-based measurements of foliar nitrogen and vegetation structure, ground-based spectroscopy, airborne LIDAR, and airborne hyperspectral surveys occurring within narrow overlapping time intervals once every five years. While many advancements have been made in linking and scaling in situ data with airborne imagery, establishing these relationships across dozens of highly variable sites poses significant challenges to understanding continental-wide processes. Here we study the relationship between foliar nitrogen content and airborne hyperspectral imagery at different study sites. NEON collected foliar samples from three sites in 2014 as part of a prototype study: Ordway Swisher Biological Station (pine-oak savannah, with active fire management), Jones Ecological Research Center (pine-oak savannah), and San Joaquin Experimental Range (grass-pine oak woodland). Leaf samples and canopy heights of dominant and co-dominant species were collected from trees located within 40 x 40 meter sampling plots within two weeks of aerial LIDAR and hyperspectral surveys. Foliar canopy samples were analyzed for leaf mass per area (LMA), stable isotopes of C and N, C/N content. We also examine agreement and uncertainty between ground based canopy height and airborne LIDAR derived digital surface models (DSM) for each site. Site-scale maps of canopy nitrogen and canopy height will also be presented.

  2. Study of SGD along the French Mediterranean coastline using airborne TIR images and in situ analyses

    NASA Astrophysics Data System (ADS)

    van Beek, Pieter; Stieglitz, Thomas; Souhaut, Marc

    2015-04-01

    Although submarine groundwater discharge (SGD) has been investigated in many places of the world, very few studies were conducted along the French coastline of the Mediterranean Sea. Almost no information is available on the fluxes of water and chemical elements associated with these SGD and on their potential impact on the geochemical cycling and ecosystems of the coastal zones. In this work, we combined the use of airborne thermal infrared (TIR) images with in situ analyses of salinity, temperature, radon and radium isotopes to study SGD at various sites along the French Mediterranean coastline and in coastal lagoons. These analyses allowed us to detect SGD sites and to quantify SGD fluxes (that include both the fluxes of fresh groundwater and recirculated seawater). In particular, we will show how the Ra isotopes determined in the La Palme lagoon were used to estimate i) the residence time of waters in the lagoon and ii) SGD fluxes.

  3. In Situ Observations of PSCs Generated by Gravity Waves

    NASA Technical Reports Server (NTRS)

    Pfister, Leonhard; Bui, Paul; Mahoney, M. J.; Gandrud, Bruce; Hipskind, K. Stephen (Technical Monitor)

    2000-01-01

    During SOLVE, the bulk of the in-situ observations of PSCs are of large scale extended structures associated with synoptic scale cooling. The nature of these structures is also determined by layers of high relative NOy that have been stretched into thin layers by advective processes. Some of the in situ observations, however, are clearly correlated with gravity wave signatures. The first goal of this work is to examine these cases and evaluate gravity wave parameters. In particular, we are interested in the intrinsic periods of the waves and their temperature amplitude, which are key ingredients in the nucleation process. Secondly, we will examine some rudimentary properties of the particle size distributions and composition, comparing these with in situ observations of the more extended PSC features. Finally, we will attempt to ascertain the mechanism which generates the gravity waves.

  4. Airborne Infrared Spectrograph for Eclipse Observations

    NASA Astrophysics Data System (ADS)

    Golub, L.; Cheimets, P.; DeLuca, E. E.; Samra, J.; Judge, P. G.

    2015-12-01

    Direct measurements of the coronal magnetic field have significant potential to enhance our understanding of coronal dynamics, and improve forecasting models. Of particular interest are observations of coronal field lines in the Transition Corona, the transitional region between closed and open flux systems, providing important information on eruptive instabilities and on the origin of the slow solar wind. While current instruments routinely observe the photospheric and chromospheric magnetic fields, the proposed airborne spectrometer will take a step toward the direct observation of coronal fields by measuring plasma emission in the infrared at high spatial and spectral resolution. The targeted lines are five forbidden magnetic dipole transitions between 1.4 and 4 um. The airborne system will consist of a telescope, grating spectrometer and pointing/stabilization system to be flown on the NSF/NCAR High-performance Instrumented Airborne Platform for Environmental Research (HIAPER) during the 21 August 2017 total solar eclipse. We will discuss the scientific objectives of the 2017 flight, describe details of the instrument design, and present the observing program for the eclipse.

  5. Identifying a Sea Breeze Circulation Pattern Over the Los Angeles Basin Using Airborne In Situ Carbon Dioxide Measurements

    NASA Astrophysics Data System (ADS)

    Brannan, A. L.; Schill, S.; Trousdell, J.; Heath, N.; Lefer, B. L.; Yang, M. M.; Bertram, T. H.

    2014-12-01

    The Los Angeles Basin in Southern California is an optimal location for a circulation study, due to its location between the Pacific Ocean to the west and the Santa Monica and San Gabriel mountain ranges to the east, as well as its booming metropolitan population. Sea breeze circulation carries air at low altitudes from coastal to inland regions, where the air rises and expands before returning back towards the coast at higher altitudes. As a result, relatively clean air is expected at low altitudes over coastal regions, but following the path of sea breeze circulation should increase the amount of anthropogenic influence. During the 2014 NASA Student Airborne Research Program, a highly modified DC-8 aircraft completed flights from June 23 to 25 in and around the LA Basin, including missed approaches at four local airports—Los Alamitos and Long Beach (coastal), Ontario and Riverside (inland). Because carbon dioxide (CO2) is chemically inert and well-suited as a conserved atmospheric tracer, the NASA Langley Atmospheric Vertical Observations of CO2 in the Earth's Troposphere (AVOCET) instrument was used to make airborne in situ carbon dioxide measurements. Combining measured wind speed and direction data from the aircraft with CO2 data shows that carbon dioxide can be used to trace the sea breeze circulation pattern of the Los Angeles basin.

  6. Airborne Sunphotometer Studies of Aerosol Properties and Effects, Including Closure Among Satellite, Suborbital Remote, and In situ Measurements

    NASA Technical Reports Server (NTRS)

    Russlee, Philip B.; Schmid, B.; Redemann, J.; Livingston, J. M.; Bergstrom, R. W.; Ramirez, S. A.; Hipskind, R. Stephen (Technical Monitor)

    2001-01-01

    Airborne sunphotometry has been used to measure aerosols from North America, Europe, and Africa in coordination with satellite and in situ measurements in TARFOX (1996), ACE-2 (1997), PRIDE (2000), and SAFARI 2000. Similar coordinated measurements of Asian aerosols are being conducted this spring in ACE-Asia and are planned for North American aerosols this summer in CLAMS. This paper summarizes the approaches used, key results, and implications for aerosol properties and effects, such as single scattering albedo and regional radiative forcing. The approaches exploit the three-dimensional mobility of airborne sunphotometry to access satellite scenes over diverse surfaces (including open ocean with and without sunglint) and to match exactly the atmospheric layers sampled by airborne in situ measurements and other radiometers. These measurements permit tests of the consistency, or closure, among such diverse measurements as aerosol size-resolved chemical composition; number or mass concentration; light extinction, absorption, and scattering (total, hemispheric back and 180 deg.); and radiative fluxes. In this way the airborne sunphotometer measurements provide a key link between satellite and in situ measurements that helps to understand any discrepancies that are found. These comparisons have led to several characteristic results. Typically these include: (1) Better agreement among different types of remote measurements than between remote and in situ measurements. (2) More extinction derived from transmission measurements than from in situ measurements. (3) Larger aerosol absorption inferred from flux radiometry than from in situ measurements. Aerosol intensive properties derived from these closure studies have been combined with satellite-retrieved fields of optical depth to produce fields of regional radiative forcing. We show results for the North Atlantic derived from AVHRR optical depths and aerosol intensive properties from TARFOX and ACE-2. Companion papers

  7. Airborne Observations of Mixed Phase Clouds in the Southern Rockies

    NASA Astrophysics Data System (ADS)

    Dorsi, S. W.; Avallone, L. M.

    2011-12-01

    Conducted over mountainous regions of Northern Colorado and Southern Wyoming during the 2010-2011 winter, the Colorado Airborne Multi-Phase Cloud Study (CAMPS) was designed to investigate the complex processes within mid-latitude, orographic, mixed-phase clouds. Over the course of 29 flights, instruments aboard the Wyoming King Air research aircraft made observations of cloud properties within diverse wintertime clouds, including many orographic mixed phase clouds. The aircraft carried a suite of in-situ cloud probes, including PMS-FSSP optical particle counter, PMS-2DC and -2DP cloud particle and precipitation imagers, Gerber PVM-100 optical and DMT LWC-100 hotwire liquid content probes, and a Rosemont icing detector. In addition, the research aircraft carried the University of Colorado closed-path laser hygrometer (CLH), which measures total water concentration by sampling the outside airstream, vaporizing condensed water particles in the sample, and observing infrared absorption in water vapor spectrum. The combination of the total water measurement from the CLH and the condensed particle measurements from the optical and hotwire cloud probes provides an opportunity to estimate the relative concentrations of cloud particles by phase. Using this host of cloud probes and the total water measurement, we develop a method for retrieving in-situ cloud water phase and concentration. We present results of this retrieval for several regions of mixed phase cloud, and describe the observed structure and evolution of these clouds.

  8. Polarized Imaging Nephelometer for in situ airborne measurements of aerosol light scattering.

    PubMed

    Dolgos, Gergely; Martins, J Vanderlei

    2014-09-01

    Global satellite remote sensing of aerosols requires in situ measurements to enable the calibration and validation of algorithms. In order to improve our understanding of light scattering by aerosol particles, and to enable routine in situ airborne measurements of aerosol light scattering, we have developed an instrument, called the Polarized Imaging Nephelometer (PI-Neph). We designed and built the PI-Neph at the Laboratory for Aerosols, Clouds and Optics (LACO) of the University of Maryland, Baltimore County (UMBC). This portable instrument directly measures the ambient scattering coefficient and phase matrix elements of aerosols, in the field or onboard an aircraft. The measured phase matrix elements are the P(11), phase function, and P(12). Lasers illuminate the sampled ambient air and aerosol, and a wide field of view camera detects scattered light in a scattering angle range of 3° to 176°. The PI-Neph measures an ensemble of particles, supplying the relevant quantity for satellite remote sensing, as opposed to particle-by-particle measurements that have other applications. Comparisons with remote sensing measurements will have to consider aircraft inlet effects. The PI-Neph first measured at a laser wavelength of 532nm, and was first deployed successfully in 2011 aboard the B200 aircraft of NASA Langley during the Development and Evaluation of satellite ValidatiOn Tools by Experimenters (DEVOTE) project. In 2013, we upgraded the PI-Neph to measure at 473nm, 532nm, and 671nm nearly simultaneously. LACO has deployed the PI-Neph on a number of airborne field campaigns aboard three different NASA aircraft. This paper describes the PI-Neph measurement approach and validation by comparing measurements of artificial spherical aerosols with Mie theory. We provide estimates of calibration uncertainties, which show agreement with the small residuals between measurements of P(11) and -P(12)/P(11) and Mie theory. We demonstrate the capability of the PI-Neph to measure

  9. Polarized Imaging Nephelometer for in situ airborne measurements of aerosol light scattering.

    PubMed

    Dolgos, Gergely; Martins, J Vanderlei

    2014-09-01

    Global satellite remote sensing of aerosols requires in situ measurements to enable the calibration and validation of algorithms. In order to improve our understanding of light scattering by aerosol particles, and to enable routine in situ airborne measurements of aerosol light scattering, we have developed an instrument, called the Polarized Imaging Nephelometer (PI-Neph). We designed and built the PI-Neph at the Laboratory for Aerosols, Clouds and Optics (LACO) of the University of Maryland, Baltimore County (UMBC). This portable instrument directly measures the ambient scattering coefficient and phase matrix elements of aerosols, in the field or onboard an aircraft. The measured phase matrix elements are the P(11), phase function, and P(12). Lasers illuminate the sampled ambient air and aerosol, and a wide field of view camera detects scattered light in a scattering angle range of 3° to 176°. The PI-Neph measures an ensemble of particles, supplying the relevant quantity for satellite remote sensing, as opposed to particle-by-particle measurements that have other applications. Comparisons with remote sensing measurements will have to consider aircraft inlet effects. The PI-Neph first measured at a laser wavelength of 532nm, and was first deployed successfully in 2011 aboard the B200 aircraft of NASA Langley during the Development and Evaluation of satellite ValidatiOn Tools by Experimenters (DEVOTE) project. In 2013, we upgraded the PI-Neph to measure at 473nm, 532nm, and 671nm nearly simultaneously. LACO has deployed the PI-Neph on a number of airborne field campaigns aboard three different NASA aircraft. This paper describes the PI-Neph measurement approach and validation by comparing measurements of artificial spherical aerosols with Mie theory. We provide estimates of calibration uncertainties, which show agreement with the small residuals between measurements of P(11) and -P(12)/P(11) and Mie theory. We demonstrate the capability of the PI-Neph to measure

  10. In situ measurements of NO(x) in the Airborne Arctic Stratospheric Expedition

    NASA Technical Reports Server (NTRS)

    Carroll, Mary Anne; Montzka, Denise D.; Hubler, Gerhard; Kelly, Kenneth K.; Gregory, Gerald L.

    1990-01-01

    In situ measurements of NO and NO2 were made simultaneously from the NASA DC-8 aircraft as part of the Airborne Arctic Stratospheric Expedition. Mixing ratios of NO(x) (NO + NO2) were typically higher in the arctic troposphere than in the stratosphere, with median values of 59 and 40 pptv, respectively. In the stratosphere, there tended to be a positive correlation between NO(x) and water vapor and negative correlations between NO(x) and ozone and between NO(x) and total reactive odd-nitrogen, NO(y). The ratio of NO(x) to NO(y), in conjunction with NO(y), appears to be an excellent tracer of tropospheric or stratospheric air at northern latitudes during winter. Tropospheric NO(x) was typically 10 to 50 percent of gas-phase NO(y), while in the stratosphere, NO(x) was typically less than 10 percent, and frequently less than 5 percent of gas-phase NO(y).

  11. Regular, Fast and Accurate Airborne In-Situ Methane Measurements Around the Tropopause

    NASA Astrophysics Data System (ADS)

    Dyroff, Christoph; Rauthe-Schöch, Armin; Schuck, Tanja J.; Zahn, Andreas

    2013-04-01

    We present a laser spectrometer for automated monthly measurements of methane (CH4) mixing ratios aboard the CARIBIC passenger aircraft. The instrument is based on a commercial fast methane analyzer (FMA, Los Gatos Res.), which was modified for fully unattended employment. A laboratory characterization was performed and the results with emphasis on the precision, cross sensitivity to H2O, and accuracy are presented. An in-flight calibration strategy is described, that utilizes CH4 measurements obtained from flask samples taken during the same flights. By statistical comparison of the in-situ measurements with the flask samples we derive a total uncetrainty estimate of ~ 3.85 ppbv (1?) around the tropopause, and ~ 12.4 ppbv (1?) during aircraft ascent and descent. Data from the first two years of airborne operation are presented that span a large part of the northern hemispheric upper troposphere and lowermost stratosphere, with occasional crossings of the tropics on flights to southern Africa. With its high spatial resolution and high accuracy this data set is unprecedented in the highly important atmospheric layer of the tropopause.

  12. In situ real-time measurement of physical characteristics of airborne bacterial particles

    NASA Astrophysics Data System (ADS)

    Jung, Jae Hee; Lee, Jung Eun

    2013-12-01

    Bioaerosols, including aerosolized bacteria, viruses, and fungi, are associated with public health and environmental problems. One promising control method to reduce the harmful effects of bioaerosols is thermal inactivation via a continuous-flow high-temperature short-time (HTST) system. However, variations in bioaerosol physical characteristics - for example, the particle size and shape - during the continuous-flow inactivation process can change the transport properties in the air, which can affect particle deposition in the human respiratory system or the filtration efficiency of ventilation systems. Real-time particle monitoring techniques are a desirable alternative to the time-consuming process of microscopic analysis that is conventionally used in sampling and particle characterization. Here, we report in situ real-time optical scattering measurements of the physical characteristics of airborne bacteria particles following an HTST process in a continuous-flow system. Our results demonstrate that the aerodynamic diameter of bacterial aerosols decreases when exposed to a high-temperature environment, and that the shape of the bacterial cells is significantly altered. These variations in physical characteristics using optical scattering measurements were found to be in agreement with the results of scanning electron microscopy analysis.

  13. Airborne in-situ spectral characterization and concentration estimates of fluorescent organics as a function of depth

    NASA Technical Reports Server (NTRS)

    Tittle, R. A.

    1988-01-01

    The primary purpose of many in-situ airborne light scattering experiments in natural waters is to spectrally characterize the subsurface fluorescent organics and estimate their relative concentrations. This is often done by shining a laser beam into the water and monitoring its subsurface return signal. To do this with the proper interpretation, depth must be taken into account. If one disregards depth dependence when taking such estimates, both their spectral characteristics and their concentrations estimates can be rather ambiguous. A simple airborne lidar configuration is used to detect the subsurface return signal from a particular depth and wavelength. Underwater scatterometer were employed to show that in-situ subsurface organics are very sensitive to depth, but they also require the use of slow moving boats to cover large sample areas. Also, their very entry into the water disturbs the sample it is measuring. The method described is superior and simplest to any employed thus far.

  14. Observing cirrus halos to constrain in-situ measurements of ice crystal size

    NASA Astrophysics Data System (ADS)

    Garrett, T. J.; Kimball, M. B.; Mace, G. G.; Baumgardner, D. G.

    2007-01-01

    In this study, characteristic optical sizes of ice crystals in synoptic cirrus are determined using airborne measurements of ice crystal size distributions, optical extinction and water content. The measurements are compared with coincident visual observations of ice cloud optical phenomena, in particular the 22° and 46° halos. In general, the scattering profiles derived from the in-situ cloud probe measurements are consistent with the observed halo characteristics. It is argued that this implies that the measured ice crystals were small, probably with characteristic optical radii between 10 and 20 μm. There is a current contention that in-situ measurements of high concentrations of small ice crystals reflect artifacts from the shattering of large ice crystals on instrument inlets. Significant shattering cannot be entirely excluded using this approximate technique, but it is not indicated. On the basis of the in-situ measurements, a parameterization is provided that relates the optical effective radius of ice crystals to the temperature in mid-latitude synoptic cirrus.

  15. SOFIA'S Challenge: Scheduling Airborne Astronomy Observations

    NASA Technical Reports Server (NTRS)

    Frank, Jeremy

    2005-01-01

    The Stratospheric Observatory for Infrared Astronomy (SOFIA) is NASA's next generation airborne astronomical observatory, and will commence operations in 2005. The facility consists of a 747-SP modified to accommodate a 2.5 meter telescope. SOFIA is expected to fly an average of 140 science flights per year over its 20 year lifetime. Depending on the nature of the instrument used during flight, 5-15 observations per flight are expected. The SOFIA telescope is mounted aft of the wings on the port side of the aircraft and is articulated through a range of 20deg to 60deg of elevation. The telescope has minimal lateral flexibility; thus, the aircraft must turn constantly to maintain the telescope's focus on an object during observations. A significant problem in future SOFIA operations is that of scheduling flights in support of observations. Investigators are expected to propose small numbers of observations, and many observations must be grouped together to make up single flights. Flight planning for the previous generation airborne observatory, the Kuiper Airborne Observatory (KAO), was done by hand; planners had to choose takeoff time, observations to perform, and decide on setup-actions (called "dead-legs") to position the aircraft prior to observing. This task frequently required between 6-8 hours to plan one flight The scope of the flight planning problem for supporting GI observations with the anticipated flight rate for SOFIA makes the manual approach for flight planning daunting. In response, we have designed an Automated Flight Planner (AFP) that accepts as input a set of requested observations, designated flight days, weather predictions and fuel limitations, and searches automatically for high-quality flight plans that satisfy all relevant aircraft and astronomer specified constraints. The AFP can generate one candidate flight plan in 5-10 minutes, of computation time, a feat beyond the capabilities of human flight planners. The rate at which the AFP can

  16. Fast in situ airborne and ground-based flux measurement of ammonia using a quantum cascade laser spectrometer

    NASA Astrophysics Data System (ADS)

    Leen, J. B.; Yu, X.; Hubbe, J.; Kluzek, C. D.; Tomlinson, J. M.; Fischer, M. L.; Reichl, K.; Gupta, M.

    2012-12-01

    are airborne feasible and capable of eddy covariance measurements provided by fast in situ observations of ammonia to advance our understanding of atmospheric compositions and aerosol formation.

  17. Fast In Situ Airborne Measurement of Ammonia Using a Mid-Infrared Off-Axis ICOS Spectrometer

    SciTech Connect

    Leen, J. Brian; Yu, Xiao-Ying; Gupta, Manish; Baer, Douglas S.; Hubbe, John M.; Kluzek, Celine D.; Tomlinson, Jason M.; Hubbell, Mike R.

    2013-08-23

    A new ammonia (NH3) analyzer was developed based on off-axis integrated cavity output spectroscopy. Its feasibility was demonstrated by making tropospheric measurements in flights aboard the Department of Energy Gulfstream-1 aircraft. The ammonia analyzer consists of an optical cell, quantum-cascade laser, gas sampling system, control and data acquisition electronics, and analysis software. The NH3 mixing ratio is determined from high-resolution absorption spectra obtained by tuning the laser wavelength over the NH3 fundamental vibration band near 9.67 μm. Excellent linearity is obtained over a wide dynamic range (0–101 ppbv) with a response rate (1/e) of 2 Hz and a precision of ±90 pptv (1σ in 1 s). Two research flights were conducted over the Yakima Valley in Washington State. In the first flight, the ammonia analyzer was used to identify signatures of livestock from local dairy farms with high vertical and spatial resolution under low wind and calm atmospheric conditions. In the second flight, the analyzer captured livestock emission signals under windy conditions. Finally, our results demonstrate that this new ammonia spectrometer is capable of providing fast, precise, and accurate in situ observations of ammonia aboard airborne platforms to advance our understanding of atmospheric compositions and aerosol formation.

  18. Fast in situ airborne measurement of ammonia using a mid-infrared off-axis ICOS spectrometer.

    PubMed

    Leen, J Brian; Yu, Xiao-Ying; Gupta, Manish; Baer, Douglas S; Hubbe, John M; Kluzek, Celine D; Tomlinson, Jason M; Hubbell, Mike R

    2013-09-17

    A new ammonia (NH3) analyzer was developed based on off-axis integrated cavity output spectroscopy. Its feasibility was demonstrated by making tropospheric measurements in flights aboard the Department of Energy Gulfstream-1 aircraft. The ammonia analyzer consists of an optical cell, quantum-cascade laser, gas sampling system, control and data acquisition electronics, and analysis software. The NH3 mixing ratio is determined from high-resolution absorption spectra obtained by tuning the laser wavelength over the NH3 fundamental vibration band near 9.67 μm. Excellent linearity is obtained over a wide dynamic range (0-101 ppbv) with a response rate (1/e) of 2 Hz and a precision of ±90 pptv (1σ in 1 s). Two research flights were conducted over the Yakima Valley in Washington State. In the first flight, the ammonia analyzer was used to identify signatures of livestock from local dairy farms with high vertical and spatial resolution under low wind and calm atmospheric conditions. In the second flight, the analyzer captured livestock emission signals under windy conditions. Our results demonstrate that this new ammonia spectrometer is capable of providing fast, precise, and accurate in situ observations of ammonia aboard airborne platforms to advance our understanding of atmospheric compositions and aerosol formation. PMID:23869496

  19. In situ observation of carbon nanotube yarn during voltage application.

    PubMed

    Tokunaga, Tomoharu; Hayashi, Yasuhiko; Iijima, Toru; Uesugi, Yuki; Unten, Masaki; Sasaki, Katsuhiro; Yamamoto, Takahisa

    2015-07-01

    Carbon nanotube (CNT) yarns are fabricated by drawing (combined with spinning) from CNT forests and grown on a substrate. Three types of phenomena occur in these CNT yarns with increasing amounts of current: yarn rotation, catalyst evaporation, and breakage of the yarn. These phenomena result from the resistive heating occurring during the current flow, and have been observed in situ under vacuum by transmission electron microscopy. If these CNT yarns are applied to electronic circuits, the rotation and breakage may lead to circuit failure. However, catalyst evaporation is a useful method for purifying CNT yarns without additional treatments prior to yarn fabrication. PMID:25939086

  20. Vertical wind retrieved by airborne lidar and analysis of island induced gravity waves in combination with numerical models and in situ particle measurements

    NASA Astrophysics Data System (ADS)

    Chouza, Fernando; Reitebuch, Oliver; Jähn, Michael; Rahm, Stephan; Weinzierl, Bernadett

    2016-04-01

    This study presents the analysis of island induced gravity waves observed by an airborne Doppler wind lidar (DWL) during SALTRACE. First, the instrumental corrections required for the retrieval of high spatial resolution vertical wind measurements from an airborne DWL are presented and the measurement accuracy estimated by means of two different methods. The estimated systematic error is below -0.05 m s-1 for the selected case of study, while the random error lies between 0.1 and 0.16 m s-1 depending on the estimation method. Then, the presented method is applied to two measurement flights during which the presence of island induced gravity waves was detected. The first case corresponds to a research flight conducted on 17 June 2013 in the Cabo Verde islands region, while the second case corresponds to a measurement flight on 26 June 2013 in the Barbados region. The presence of trapped lee waves predicted by the calculated Scorer parameter profiles was confirmed by the lidar and in situ observations. The DWL measurements are used in combination with in situ wind and particle number density measurements, large-eddy simulations (LES), and wavelet analysis to determine the main characteristics of the observed island induced trapped waves.

  1. Passive remote sensing of large-scale methane emissions from Oil Fields in California's San Joaquin Valley and validation by airborne in-situ measurements - Results from COMEX

    NASA Astrophysics Data System (ADS)

    Gerilowski, Konstantin; Krautwurst, Sven; Thompson, David R.; Thorpe, Andrew K.; Kolyer, Richard W.; Jonsson, Haflidi; Krings, Thomas; Frankenberg, Christian; Horstjann, Markus; Leifer, Ira; Eastwood, Michael; Green, Robert O.; Vigil, Sam; Fladeland, Matthew; Schüttemeyer, Dirk; Burrows, John P.; Bovensmann, Heinrich

    2016-04-01

    The CO2 and MEthane EXperiment (COMEX) was a NASA and ESA funded campaign in support of the HyspIRI and CarbonSat mission definition activities. As a part of this effort, seven flights were performed between June 3 and September 4, 2014 with the Methane Airborne MAPper (MAMAP) remote sensing instrument (operated by the University of Bremen in cooperation with the German Research Centre for Geosciences - GFZ) over the Kern River, Kern Front, and Poso Creek Oil Fields located in California's San Joaquin Valley. MAMAP was installed for the flights aboard the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter aircraft, together with: a Picarro fast in-situ greenhouse gas (GHG) analyzer operated by the NASA Ames Research Center, ARC; a 5-hole turbulence probe; and an atmospheric measurement package operated by CIRPAS measuring aerosols, temperature, dew-point, and other atmospheric parameters. Three of the flights were accompanied by the Next Generation Airborne Visual InfraRed Imaging Spectrometer (AVIRIS-NG), operated by the Jet Propulsion Laboratory (JPL), California Institute of Technology, installed aboard a second Twin Otter aircraft. Large-scale, high-concentration CH4 plumes were detected by the MAMAP instrument over the fields and tracked over several kilometers. The spatial distribution of the MAMAP observed plumes was compared to high spatial resolution CH4 anomaly maps derived by AVIRIS-NG imaging spectroscopy data. Remote sensing data collected by MAMAP was used to infer CH4 emission rates and their distributions over the three fields. Aggregated emission estimates for the three fields were compared to aggregated emissions inferred by subsequent airborne in-situ validation measurements collected by the Picarro instrument. Comparison of remote sensing and in-situ flux estimates will be presented, demonstrating the ability of airborne remote sensing data to provide accurate emission estimates for concentrations above the

  2. Electromechanical instabilities of thermoplastics: Theory and in situ observation.

    PubMed

    Wang, Qiming; Niu, Xiaofan; Pei, Qibing; Dickey, Michael D; Zhao, Xuanhe

    2012-10-01

    Thermoplastics under voltages are used in diverse applications ranging from insulating cables to organic capacitors. Electromechanical instabilities have been proposed as a mechanism that causes electrical breakdown of thermoplastics. However, existing experiments cannot provide direct observations of the instability process, and existing theories for the instabilities generally assume thermoplastics are mechanically unconstrained. Here, we report in situ observations of electromechanical instabilities in various thermoplastics. A theory is formulated for electromechanical instabilities of thermoplastics under different mechanical constraints. We find that the instabilities generally occur in thermoplastics when temperature is above their glass transition temperatures and electric field reaches a critical value. The critical electric field for the instabilities scales with square root of yield stress of the thermoplastic and depends on its Young's modulus and hardening property.

  3. AVIATR - Aerial Vehicle for In-situ and Airborne Titan Reconnaissance A Titan Airplane Mission Concept

    NASA Technical Reports Server (NTRS)

    Barnes, Jason W.; Lemke, Lawrence; Foch, Rick; McKay, Christopher P.; Beyer, Ross A.; Radebaugh, Jani; Atkinson, David H.; Lorenz, Ralph D.; LeMouelic, Stephane; Rodriguez, Sebastien; Gundlach, Jay; Giannini, Francesco; Bain, Sean; Flasar, F. Michael; Hurford, Terry; Anderson, Carrie M.; Merrison, Jon; Adamkovics, Mate; Kattenhorn, Simon A.; Mitchell, Jonathan; Burr, Devon M.; Colaprete, Anthony; Schaller, Emily; Friedson, A. James; Edgett, Kenneth S.; Coradini, Angioletta; Adriani, Alberto; Sayanagi, Kunio M.; Malaska, Michael J.; Morabito, David; Reh, Kim

    2011-01-01

    We describe a mission concept for a stand-alone Titan airplane mission: Aerial Vehicle for In-situ and Airborne Titan Reconnaissance (AVIATR). With independent delivery and direct-to-Earth communications, AVIATR could contribute to Titan science either alone or as part of a sustained Titan Exploration Program. As a focused mission, AVIATR as we have envisioned it would concentrate on the science that an airplane can do best: exploration of Titan's global diversity. We focus on surface geology/hydrology and lower-atmospheric structure and dynamics. With a carefully chosen set of seven instruments-2 near-IR cameras, 1 near-IR spectrometer, a RADAR altimeter, an atmospheric structure suite, a haze sensor, and a raindrop detector-AVIATR could accomplish a significant subset of the scientific objectives of the aerial element of flagship studies. The AVIATR spacecraft stack is composed of a Space Vehicle (SV) for cruise, an Entry Vehicle (EV) for entry and descent, and the Air Vehicle (AV) to fly in Titan's atmosphere. Using an Earth-Jupiter gravity assist trajectory delivers the spacecraft to Titan in 7.5 years, after which the AVIATR AV would operate for a 1-Earth-year nominal mission. We propose a novel 'gravity battery' climb-then-glide strategy to store energy for optimal use during telecommunications sessions. We would optimize our science by using the flexibility of the airplane platform, generating context data and stereo pairs by flying and banking the AV instead of using gimbaled cameras. AVIATR would climb up to 14 km altitude and descend down to 3.5 km altitude once per Earth day, allowing for repeated atmospheric structure and wind measurements all over the globe. An initial Team-X run at JPL priced the AVIATR mission at FY10 $715M based on the rules stipulated in the recent Discovery announcement of opportunity. Hence we find that a standalone Titan airplane mission can achieve important science building on Cassini's discoveries and can likely do so within

  4. Annual Greenland accumulation derived from airborne radar and comparisons to modeled and in situ data

    NASA Astrophysics Data System (ADS)

    Koenig, L.; Ivanoff, A.; Alexander, P. M.; MacGregor, J. A.; Cullather, R. I.; Nowicki, S.

    2015-12-01

    Mass loss across the Greenland Ice Sheet (GrIS) has accelerated in recent decades and recently a fundamental change in the nature of this mass loss has begun. The dominant GrIS mass-loss process has switched from ice dynamics to surface mass balance (SMB) processes, including melt generation and runoff. This recent shift further emphasizes the need to monitor and constrain SMB, which, across most of the GrIS, is dominated by accumulation. High resolution, near-surface radar data have shown good fidelity at mapping spatial patterns of accumulation to validate model outputs. To better constrain accumulation over the GrIS, we derive annual accumulation rates using NASA Operation IceBridge (OIB) Snow Radar data collected from 2009 through 2012. Accumulation is calculated using the radar-determined depth to an annual layer and the local snow/firn density profile. Up to 30 years of annual stratigraphy is observed in the interior of the ice sheet, near Summit Station, while only the past year is detectable in the ablation zone around the perimeter of the ice sheet. Annual layering is traced using a semi-automatic algorithm and mapped across large areas (tens of thousands of line kilometers). A combined measured and modeled density profile is used to convert the annual stratigraphy into accumulation. Modeled density profiles from the Modèle Atmosphérique Régional (MAR) model are shown to be less than half of in situ observations in the top 1 m of snow/firn and are, therefore, replaced with in situ measurements. Using a compilation of in situ measurements, the mean GrIS snow/firn density is found to be ~340 +/- 40 kg/m3 in the top 1 m. Error in the snow density profile represents the largest error in the radar-derived accumulation. The pattern of radar-derived accumulation rate compares well with MAR estimates, although the latter has a mean bias of 4.6 cm water equivalent, a root mean square error of 16.8 cm water equivalent and a correlation coefficient of 0.6 across

  5. A study to identify and compare airborne systems for in-situ measurements of launch vehicle effluents

    NASA Technical Reports Server (NTRS)

    Thomas, T. J.; Chace, A. S.

    1974-01-01

    An in-situ system for monitoring the concentration of HCl, CO, CO2, and Al2O3 in the cloud of reaction products that form as a result of a launch of solid propellant launch vehicle is studied. A wide array of instrumentation and platforms are reviewed to yield the recommended system. An airborne system suited to monitoring pollution concentrations over urban areas for the purpose of calibrating remote sensors is then selected using a similar methodology to yield the optimal configuration.

  6. Fusing enhanced radar precipitation, in-situ hydrometeorological measurements and airborne LIDAR snowpack estimates in a hyper-resolution hydrologic model to improve seasonal water supply forecasts

    NASA Astrophysics Data System (ADS)

    Gochis, D. J.; Busto, J.; Howard, K.; Mickey, J.; Deems, J. S.; Painter, T. H.; Richardson, M.; Dugger, A. L.; Karsten, L. R.; Tang, L.

    2015-12-01

    Scarcity of spatially- and temporally-continuous observations of precipitation and snowpack conditions in remote mountain watersheds results in fundamental limitations in water supply forecasting. These limitationsin observational capabilities can result in strong biases in total snowmelt-driven runoff amount, the elevational distribution of runoff, river basin tributary contributions to total basin runoff and, equally important for water management, the timing of runoff. The Upper Rio Grande River basin in Colorado and New Mexico is one basin where observational deficiencies are hypothesized to have significant adverse impacts on estimates of snowpack melt-out rates and on water supply forecasts. We present findings from a coordinated observational-modeling study within Upper Rio Grande River basin whose aim was to quanitfy the impact enhanced precipitation, meteorological and snowpack measurements on the simulation and prediction of snowmelt driven streamflow. The Rio Grande SNOwpack and streamFLOW (RIO-SNO-FLOW) Prediction Project conducted enhanced observing activities during the 2014-2015 water year. Measurements from a gap-filling, polarimetric radar (NOXP) and in-situ meteorological and snowpack measurement stations were assimilated into the WRF-Hydro modeling framework to provide continuous analyses of snowpack and streamflow conditions. Airborne lidar estimates of snowpack conditions from the NASA Airborne Snow Observatory during mid-April and mid-May were used as additional independent validations against the various model simulations and forecasts of snowpack conditions during the melt-out season. Uncalibrated WRF-Hydro model performance from simulations and forecasts driven by enhanced observational analyses were compared against results driven by currently operational data inputs. Precipitation estimates from the NOXP research radar validate significantly better against independent in situ observations of precipitation and snow-pack increases

  7. In situ signatures of residual plasmaspheric plumes: Observations and simulation

    NASA Astrophysics Data System (ADS)

    Goldstein, J.; Thomsen, M. F.; DeJong, A.

    2014-06-01

    We compare in situ observations of the Los Alamos National Laboratory (LANL) Magnetospheric Plasma Analyzers with output of a dynamic, plasmapause test particle (PTP) simulation for the moderately disturbed interval 18-20 January 2000. In the model, weakly enhanced convection on 18 January creates a narrow drainage plume (plume A) that wraps completely around the main torus. Moderate convection on 19 January triggers significant plasmaspheric erosion, forming a second plume (B) that coexists with the narrow, wrapped, residual plume A. We fly three virtual LANL satellites through the simulation domain. The observations are globally consistent with the PTP simulation; LANL data contain several intervals of plume plasma in the model's predicted magnetic local time (MLT) sector. The modeled durations of plume sector transits are in good agreement with the LANL data. On a subglobal scale, the MLT widths and timings of the simulated plumes do not precisely agree with observations. However, several observation intervals exhibit good morphological agreement with virtual spacecraft signatures of two distinct, coexisting plumes (A and B). The fine-scale structure in the PTP model arises from the merging of residual plume A with the newer plume B. Plume merging is one theoretical means of generating fine structure in the plasmasphere: during multiple cycles of erosion and recovery, successive layers of wrapped, residual plumes can merge with newer plumes, creating layers of filamentary density structure. The model-data comparisons suggest that the plasmaspheric density distribution may preserve some memory of prior epochs of erosion and recovery.

  8. Upper Arctic Ocean velocity structure from in-situ observations

    NASA Astrophysics Data System (ADS)

    Recinos, Beatriz; Rabe, Benjamin; Schauer, Ursula

    2016-04-01

    The gross circulation of the upper and intermediate layers of the Arctic Ocean has been inferred from water mass properties: the mixed layer, containing fresh water from the shelf seas, travels from Siberia towards the Atlantic sector, and the saline and warm layer of Atlantic origin below, follows cyclonic pathways along topographic features. Direct observations of the flow below the sea ice are, however, sparse and difficult to obtain. This research presents the analysis of a unique time series/section of in situ velocity measurements obtained by a drifting ice-tethered platform in the Transpolar Drift near the North Pole. Two instruments were used to obtain in situ measurements of velocity, temperature, salinity and pressure: an Ice-tethered Acoustic Current profiler (ITAC) and an Ice-tethered Profiler (ITP). Both systems were deployed in the Amundsen basin, during the Arctic Ocean expedition ARK XXII/2 of the German Research Vessel Polarstern in September 2007. The systems transmitted profile data from the 14th of September to the 29th of November 2007 and covered a maximum depth range of 23 to 400 m. The results are compared to observations by a shipboard Acoustic Doppler Current Profiler (ADCP) from the 2011 Polarstern expedition ARK-XXVI/3, and wind and ice concentration from satellite reanalysis products. The data set allows an overview of the upper and intermediate circulation along the Lomonosov Ridge. Near-surface velocity and ice drift obtained by the ITAC unit are consistent with the Transpolar Drift Current. Ekman transports calculated from the observed ice drift and assumed ice-ocean drag behaviour suggest that Ekman dynamics influenced velocities at depths greater than the Ekman layer. Direct velocity observations in combination with water mass analyses from the temperature and salinity data, suggest the existence of a current along the Eurasian side of the Lomonosov Ridge within the warm Atlantic layer below the cold halocline. At those depths

  9. The Relationship Between Fossil and Dairy Greenhouse Gas Emissions and Complex Urban Land-Use Patterns by In Situ and Remote Sensing Data from Surface Mobile, Airborne, and Satellite Instruments

    NASA Astrophysics Data System (ADS)

    Leifer, I.; Melton, C.; Tratt, D. M.; Kuze, A.; Buckland, K. N.; Butz, A.; Deguchi, A.; Eastwood, M. L.; Fischer, M. L.; Frash, J.; Fladeland, M. M.; Gore, W.; Iraci, L. T.; Johnson, P. D.; Kataoka, F.; Kolyer, R.; Leen, J. B.; Quattrochi, D. A.; Shiomi, K.; Suto, H.; Tanaka, T.; Thompson, D. R.; Yates, E. L.; Van Damme, M.; Yokota, T.

    2015-12-01

    The GOSAT-COMEX-IASI Experiment (Greenhouse gases Observing SATellite-CO2and Methane EXperiment) demonstrated a novel approach to airborne-surface mobile in situ data fusion for interpretation and validation of satellite and airborne remote sensing data of greenhouse gases and direct calculation of flux. Key data were collected for the Chino Dairy in the Los Angeles Basin, California and for the Kern River Oil Fields adjacent to Bakersfield, California. In situ surface and remote sensing greenhouse gas and ammonia observations were compared with IASI and GOSAT retreivals, while hyperspectral imaging data from the AVIRIS, AVIRIS NG, and Mako airborne sensors were analyzed to relate emissions and land use. Figure - platforms participating in the experiment. TANSO-FTS aboard the Ibuki satellite (GOSAT) provided targeted pixels to measure column greenhouse gases. AMOG is the AutoMObile Gas Surveyor which supports a suite of meteorology and in situ trace gas sensors for mobile high speed measurement. AVIRIS, the Airborne Visual InfraRed Imaging Spectrometer aboard the NASA ER-2 airplane collected hyperspectral imaging data at 20 m resolution from 60,000 ft. Mako is a thermal infrared imaging spectrometer that was flown on the Twin Otter International. AJAX is a fighter jet outfitted for science sporting meteorology and greenhouse gas sensors. RAMVan is an upward looking FTIR for measuring column methane and ammonia and other trace gases.

  10. In situ observations of medium frequency auroral radio emissions

    NASA Astrophysics Data System (ADS)

    Broughton, M.; Labelle, J. W.; Pfaff, R. F.; Parrot, M.; Yan, X.; Burchill, J. K.

    2013-12-01

    The auroral ionosphere is a region rich with plasma waves that can be studied both in space and on the ground. These waves may mediate energy exchange between particle populations and provide information about the local plasma properties and boundaries. Auroral medium frequency (MF) burst is an impulsive radio emission observed at ground-level from 1.3-4.5 MHz that is associated with local substorm onset. There have been two recent reports of impulsive, broadband, MF waves at high latitudes. Burchill and Pfaff [2005] reported observations from the FAST satellite of impulsive, broadband, MF and low frequency (LF) radio waves. Using data from the DEMETER satellite, Parrot et al. [2009] surveyed MF waves caused by lightning. This study did show a high-latitude population of MF waves. We investigate whether the waves observed by these two satellites are related to auroral MF burst. Using FAST satellite burst mode electric field data from high-latitude (> 60 degrees magnetic), low-altitude (< 1000 km) intervals of moderate to large geomagnetic activity (Kp > 3) from 1996-2002, we have found forty-four examples of impulsive MF waves, all of which are associated with impulsive LF waves. Although MF burst and the waves observed by FAST have similar spectral signatures, they have different magnetic local time dependencies, which suggests that they may be unrelated. A study of MF waves observed at high latitude by DEMETER is ongoing. In situ observations of MF burst could provide crucial information about this heretofore unexplained natural radio emission.

  11. Analysis of Marine Stratocumulus Drizzle Variability Using In Situ Observations

    NASA Astrophysics Data System (ADS)

    Witte, M.; Chuang, P. Y.; Rossiter, D.

    2013-12-01

    Precipitation is an important factor in the dynamics and large-scale organization of marine stratocumulus, yet it remains poorly understood. We aim to elucidate the factors driving the amount and variability of marine stratocumulus drizzle using in situ observations. We use aircraft measurements from two regions: a) in the near-coastal region of Monterey, CA during the Physics of Stratocumulus Top (POST) project from July and August 2008 and b) in the near-coastal region of Iquique, Chile during the VAMOS Ocean-Cloud-Atmosphere-Land Study (VOCALS) from October 2008. Using these two different projects, we examine whether or not changes in conditions such as boundary layer depth, cloud top liquid water content, aerosol or drop concentrations, turbulence strength and inversion strength affect drizzle amount and variability. Interpreting which of these factors tend to associate most closely with various measures of drizzle intensity and variability will give insight into processes relevant to both precipitation formation and maintenance, and hopefully help explain how stratocumulus organize into the large-scale cellular patterns observed.

  12. In Situ TEM Observation of Dislocation Evolutionin Polycrystalline UO2

    SciTech Connect

    L. F. HE; 1 M. A. KIRK; Argonne National Laboratory; J. Gan; T. R. ALLEN

    2014-10-01

    In situ transmission electron microscopy observation of polycrystalline UO2 (with average grain size of about 5 lm) irradiated with Kr ions at 600C and 800C was conducted to understand the radiation-induced dislocation evolution under the influence of grain boundaries. The dislocation evolution in the grain interior of polycrystalline UO2 was similar under Kr irradiation at different ion energies and temperatures. As expected, it was characterized by the nucleation and growth of dislocation loops at low irradiation doses, followed by transformation to extended dislocation lines and tangles at high doses. For the first time, a dislocation-denuded zone was observed near a grain boundary in the 1-MeV Kr-irradiated UO2 sample at 800C. The denuded zone in the vicinity of grain boundary was not found when the irradiation temperature was at 600C. The suppression of dislocation loop formation near the boundary is likely due to the enhanced interstitial diffusion toward grain boundary at the high temperature.

  13. First Results from the COFFEE Instrument: Airborne In-Situ Measurements of Formaldehyde over California

    NASA Astrophysics Data System (ADS)

    Iraci, L. T.; St Clair, J.; Marrero, J. E.; Gore, W.; Swanson, A. K.; Hanisco, T. F.

    2015-12-01

    The Compact Formaldehyde Fluorescence Experiment (COFFEE) instrument uses Non-Resonant Laser Induced Fluorescence (NR-LIF) to detect trace concentrations of formaldehyde as part of the Alpha Jet Atmospheric eXperiment (AJAX) payload. COFFEE, developed at NASA-GSFC, has a sensitivity of 100 pptv (1 sec) and can operate over a wide range of altitudes from the boundary layer to the lower stratosphere. It is mounted in an external wing pod on the Alpha Jet aircraft based at NASA-ARC, which can access altitudes from the surface up to 40,000 ft. We will present results from test flights performed in Fall 2015 over the Central Valley of California. Targets include an oil field, agricultural areas, and highways. Formaldehyde is one of the few urban pollutants that can be measured from space, and we will present plans to compare COFFEE in-situ data with space-based formaldehyde observations such as those from OMI (Aura) and OMPS (SuomiNPP).

  14. Understanding the Solar Sources of In Situ Observations

    NASA Technical Reports Server (NTRS)

    Riley, Pete; Mikic, Zoran; Linker, Jon; Zurbuchen, Thomas H.

    2002-01-01

    The solar wind can, to a good approximation be described as a two component flow with fast, tenuous, quiescent flow emanating from coronal holes, and slow, dense and variable flow associated with the boundary between open and closed magnetic fields. In spite of its simplicity, this picture naturally produces a range of complex heliospheric phenomena, including the presence, location, and orientation of corotating interaction regions and their associated shocks. In this study, we apply a two-step mapping technique, incorporating a magnetohydrodynamic model of the solar corona, to bring in situ observations h m Ulysses, WIND, and ACE back to the solar surface in an effort to determine some intrinsic properties of the quasi-steady solar wind. In particular, we find that a "layer" of approx. 35,000 h n exists between the Coronal Hole Boundary (CHB) and the fast solar wind, where the wind is slow and variable. We also- derive a velocity gradient within large polar coronal boles (that were present during Ulysses rapid latitude scan) as a function of distance from the CHB. We find that nu = 713 km/s + 3.2 d, where d is the angular distance from the CHB boundary in degrees.

  15. COMET: a planned airborne mission to simultaneously measure CO2 and CH4 columns using airborne remote sensing and in-situ techniques

    NASA Astrophysics Data System (ADS)

    Fix, A.; Amediek, A.; Büdenbender, C.; Ehret, G.; Wirth, M.; Quatrevalet, M.; Rapp, M.; Gerilowski, K.; Bovensmann, H.; Gerbig, C.; Pfeilsticker, K.; Zöger, M.; Giez, A.

    2013-12-01

    To better predict future trends in the cycles of the most important anthropogenic greenhouse gases, CO2 and CH4, there is a need to measure and understand their distribution and variation on various scales. To address these requirements it is envisaged to deploy a suite of state-of-the-art airborne instruments that will be capable to simultaneously measure the column averaged dry-air mixing ratios (XGHG) of both greenhouse gases along the flight path. As the measurement platform serves the research aircraft HALO, a modified Gulfstream G550, operated by DLR. This activity is dubbed CoMet (CO2 and Methane Mission). The instrument package of CoMet will consist of active and passive remote sensors as well as in-situ instruments to complement the column measurements by highly-resolved profile information. As an active remote sensing instrument CHARM-F, the integrated-path differential absorption lidar currently under development at DLR, will provide both, XCO2 and XCH4, below flight altitude. The lidar instrument will be complemented by MAMAP which is a NIR/SWIR absorption spectrometer developed by University of Bremen and which is also capable to derive XCH4 and XCO2. As an additional passive instrument, mini-DOAS operated by University of Heidelberg will contribute with additional context information about the investigated air masses. In order to compare the remote sensing instruments with integrated profile information, in-situ instrumentation is indispensable. The in-situ package will therefore comprise wavelength-scanned Cavity-Ring-Down Spectroscopy (CRDS) for the detection of CO2, CH4, CO and H2O and a flask sampler for collection of atmospheric samples and subsequent laboratory analysis. Furthermore, the BAsic HALO Measurement And Sensor System (BAHAMAS) will provide an accurate set of meteorological and aircraft state parameters for each scientific flight. Within the frame of the first CoMet mission scheduled for the 2015 timeframe it is planned to concentrate

  16. Obtaining Io's internal state from in situ and remote observations

    NASA Astrophysics Data System (ADS)

    Khurana, Krishan; Keszthelyi, Laszlo; Jia, Xianzhe; McEwen, Alfred

    2016-04-01

    Based on sound theoretical arguments, Io has long been suspected of harboring a magma ocean in its interior. The extremely high temperature of the lava erupting on Io's surface indeed hint at an extremely hot interior consistent with an internal magma ocean. However, the only direct evidence for a melt layer in Io's interior has been provided by Khurana et al. (2011), who used Jupiter's rotating magnetic field as an electromagnetic induction signal. They have shown that a strong dipolar field is present in Galileo magnetometer data, which is consistent with electromagnetic induction from large amounts of rock-melts in Io's interior. Modeling of this signature showed that the induction response from a completely solid mantle model is inadequate to explain the magnetometer observations. However, they found that a layer of asthenosphere > 50 km in thickness with a rock melt fraction ≥ 20% is adequate to accurately model the observed magnetic field. In this presentation, we first provide a progress report on our effort to marry the principles of thermodynamics with those of electromagnetism to further constrain the temperature profile inside Io. The constraints on the mineralogy, temperature and melt state of Io are being obtained from MELTS a modeling program that utilizes thermodynamic principles to calculate the chemical variations in the assemblages of minerals and melts as a function of pressure, temperature and oxygen fugacity. Electromagnetic induction response is calculated by solving the induction equation numerically for several different models of the interior and tested for their agreement with the Galileo magnetometer data. Next, we explore how future in situ and remote observations could be used to characterize Io's interior using multi-frequency electromagnetic induction and auroral observations. We show that the lithospheric thickness can be obtained from induction response at the Jovian synodic period while information on the magma ocean thickness

  17. Simultaneous Observations of Coastal Salinity Features by SMOS and STARRS, and Comparisons with In Situ Data

    NASA Astrophysics Data System (ADS)

    Burrage, D. M.; Wesson, J. C.; Wang, D. W.; Hwang, P. A.; Howden, S. D.; Chu, Y. P.; Book, J. W.

    2012-12-01

    The main oceanographic mission of the Soil Moisture and Ocean Salinity (SMOS) and Aquarius satellites is to map global ocean salinity monthly at ~200 km resolution and ~0.2 psu precision. However, observations of smaller scale, short term, ocean variability due to large-scale river plumes, hurricanes and tropical instability waves have been reported. Our goal is to evaluate the utility of SMOS data for mapping Sea Surface Salinity (SSS) in coastal seas, where land contamination and wind variations due to topography generate significant errors. The approach is to compare SMOS SSS data with airborne L-band radiometer and in situ platform measurements, and with predictions of regional circulation models. Observation of shelf-scale circulation features using the MIRAS radiometer, with beam footprints ranging from ~32-100 km is an attractive but challenging task. However, the larger signal-to-noise or 'SN' ratios of salinity in specific coastal areas permits data processing with less severe temporal and spatial averaging than is needed over the open ocean. Smaller scale features can be studied by analysing Level 2 swath data, in preference to Level 3 products used in the deep ocean. The main question is: What is an acceptable SN ratio in a specific region? We report simultaneous satellite, airborne and in situ observations of salinity variations produced by river plumes, boundary currents and associated eddies. In recent field experiments in the Gulf of Mexico (COSSAR) and off Virginia (VIRGO), we under-flew SMOS with NRL's L-, C- and IR-band airborne radiometer system - the Salinity Temperature and Roughness Remote Scanner (STARRS), to obtain brightness temperature measurements over NOAA data buoys under various wind conditions and study the effects of sea surface roughness and roughness model correction errors on SSS retrieval. In addition, we compared SMOS data with in situ and shipboard data acquired during a mesoscale circulation and internal wave study (ADAPTER

  18. Airborne In-Situ Measurements of Formaldehyde over California: First Results from the COFFEE Instrument

    NASA Astrophysics Data System (ADS)

    Marrero, Josette; St. Clair, Jason; Yates, Emma; Swanson, Andrew; Gore, Warren; Iraci, Laura; Hanisco, Thomas

    2016-04-01

    Formaldehyde (HCHO) is one of the most abundant oxygenated volatile organic compounds (VOCs) in the atmosphere, playing a role multiple atmospheric processes. Measurements of HCHO can be used to help quantify convective transport, the abundance of VOCs, and ozone production in urban environments. The Compact Formaldehyde FluorescencE Experiment (COFFEE) instrument uses Non-Resonant Laser Induced Fluorescence (NR-LIF) to detect trace concentrations of HCHO as part of the Alpha Jet Atmospheric eXperiment (AJAX) payload. Developed at NASA GSFC, COFFEE is a small, low maintenance instrument with a sensitivity of 100 pptv and a quick response time (1 sec). The COFFEE instrument has been customized to fit in an external wing pod on the Alpha Jet aircraft based at NASA ARC. The instrument can operate over a broad range of altitudes, from boundary layer to lower stratosphere, making it well suited for the Alpha Jet, which can access altitudes from the surface up to 40,000 ft. We will present results from flights performed over the Central Valley of California, including boundary layer measurements and vertical profiles in the tropospheric column. This region is of particular interest, due to its elevated levels of HCHO, revealed in satellite images, as well as its high ozone concentrations. In addition to HCHO, the AJAX payload includes measurements of atmospheric ozone, methane, and carbon dioxide. These results will be presented in conjunction with formaldehyde. Targets in the Central Valley consist of an oil field, agricultural areas, and highways, each of which can emit HCHO primarily and generate HCHO through secondary production. Formaldehyde is one of the few urban pollutants that can be measured from space. Plans to compare in-situ COFFEE data with satellite-based HCHO observations such as those from OMI (Aura) and OMPS (SuomiNPP) will also be presented.

  19. The Saturn Ring Observer: In situ studies of planetary rings

    NASA Astrophysics Data System (ADS)

    Nicholson, P. D.; Tiscareno, M. S.; Spilker, L. J.

    2010-12-01

    As part of the Planetary Science Decadal Survey recently undertaken by the NRC's Space Studies Board for the National Academy of Sciences, studies were commissioned for a number of potential missions to outer planet targets. One of these studies examined the technological feasibility of a mission to carry out in situ studies of Saturn's rings, from a spacecraft placed in a circular orbit above the ring plane: the Saturn Ring Observer. The technical findings and background are discussed in a companion poster by T. R. Spilker et al. Here we outline the science goals of such a mission. Most of the fundamental interactions in planetary rings occur on spatial scales that are unresolved by flyby or orbiter spacecraft. Typical particle sizes in the rings of Saturn are in the 1 cm - 10 m range, and average interparticle spacings are a few meters. Indirect evidence indicates that the vertical thickness of the rings is as little as 5 - 10 m, which implies a velocity dispersion of only a few mm/sec. Theories of ring structure and evolution depend on the unknown characteristics of interparticle collisions and on the size distribution of the ring particles. The SRO could provide direct measurements of both the coefficient of restitution -- by monitoring individual collisions -- and the particles’ velocity dispersion. High-resolution observations of individual ring particles should also permit estimates of their spin states. Numerical simulations of Saturn’s rings incorporating both collisions and self-gravity predict that the ring particles are not uniformly distributed, but are instead clustered into elongated structures referred to as “self-gravity wakes”, which are continually created and destroyed on an orbital timescale. Theory indicates that the average separation between wakes in the A ring is of order 30-100 m. Direct imaging of self-gravity wakes, including their formation and subsequent dissolution, would provide critical validation of these models. Other

  20. Aerosol classification by airborne high spectral resolution lidar observations

    NASA Astrophysics Data System (ADS)

    Groß, S.; Esselborn, M.; Weinzierl, B.; Wirth, M.; Fix, A.; Petzold, A.

    2013-03-01

    During four aircraft field experiments with the DLR research aircraft Falcon in 1998 (LACE), 2006 (SAMUM-1) and 2008 (SAMUM-2 and EUCAARI), airborne High Spectral Resolution Lidar (HSRL) and in situ measurements of aerosol microphysical and optical properties were performed. Altogether, the properties of six different aerosol types and aerosol mixtures - Saharan mineral dust, Saharan dust mixtures, Canadian biomass burning aerosol, African biomass burning mixture, anthropogenic pollution aerosol, and marine aerosol have been studied. On the basis of this extensive HSRL data set, we present an aerosol classification scheme which is also capable to identify mixtures of different aerosol types. We calculated mixing lines that allowed us to determine the contributing aerosol types. The aerosol classification scheme was supported by backward trajectory analysis and validated with in-situ measurements. Our results demonstrate that the developed aerosol mask is capable to identify complex stratifications with different aerosol types throughout the atmosphere.

  1. Aerosol classification by airborne high spectral resolution lidar observations

    NASA Astrophysics Data System (ADS)

    Groß, S.; Esselborn, M.; Weinzierl, B.; Wirth, M.; Fix, A.; Petzold, A.

    2012-10-01

    During four aircraft field experiments with the DLR research aircraft Falcon in 1998 (LACE), 2006 (SAMUM-1) and 2008 (SAMUM-2 and EUCAARI), airborne High Spectral Resolution Lidar (HSRL) and in situ measurements of aerosol microphysical and optical properties were performed. Altogether, the properties of six different aerosol types and aerosol mixtures - Saharan mineral dust, Saharan dust mixtures, Canadian biomass burning aerosol, African biomass burning aerosol, anthropogenic pollution aerosol, and marine aerosol have been studied. On the basis of this extensive HSRL data set, we present an aerosol classification scheme which is also capable to identify mixtures of different aerosol types. We calculated mixing lines that allowed us to determine the contributing aerosol types. The aerosol classification scheme was validated with in-situ measurements and backward trajectory analyses. Our results demonstrate that the developed aerosol mask is capable to identify complex stratifications with different aerosol types throughout the atmosphere.

  2. An airborne infrared laser spectrometer for in-situ trace gas measurements: application to tropical convection case studies

    NASA Astrophysics Data System (ADS)

    Catoire, V.; Krysztofiak, G.; Robert, C.; Chartier, M.; Jacquet, P.; Guimbaud, C.; Hamer, P. D.; Marécal, V.

    2015-09-01

    A three-channel laser absorption spectrometer called SPIRIT (SPectromètre InfraRouge In situ Toute altitude) has been developed for airborne measurements of trace gases in the troposphere and lower stratosphere. More than three different species can be measured simultaneously with high time resolution (each 1.6 s) using three individual CW-DFB-QCLs (Continuous Wave Distributed FeedBack Quantum Cascade Lasers) coupled to a single Robert multipass optical cell. The lasers are operated in a time-multiplexed mode. Absorption of the mid-infrared radiations occur in the cell (2.8 L with effective path lengths of 134 to 151 m) at reduced pressure, with detection achieved using a HgCdTe detector cooled by Stirling cycle. The performances of the instrument are described, in particular precisions of 1, 1 and 3 %, and volume mixing ratio (vmr) sensitivities of 0.4, 6 and 2.4 ppbv are determined at 1.6 s for CO, CH4 and N2O, respectively (at 1σ confidence level). Estimated accuracies without calibration are about 6 %. Dynamic measuring ranges of about four decades are established. The first deployment of SPIRIT was realized aboard the Falcon-20 research aircraft operated by DLR (Deutsches Zentrum für Luft- und Raumfahrt) within the frame of the SHIVA (Stratospheric Ozone: Halogen Impacts in a Varying Atmosphere) European project in November-December 2011 over Malaysia. The convective outflows from two large convective systems near Borneo Island (6.0° N-115.5° E and 5.5° N-118.5° E) were sampled above 11 km in altitude on 19 November and 9 December, respectively. Correlated enhancements in CO and CH4 vmr were detected when the aircraft crossed the outflow anvil of both systems. These enhancements were interpreted as the fingerprint of transport from the boundary layer up through the convective system and then horizontal advection in the outflow. Using these observations, the fraction of boundary layer air contained in fresh convective outflow was calculated to range

  3. In situ nonlinear elastic behavior of soil observed by DAET

    SciTech Connect

    Larmat, Carene; Renaud, Guillaume; Rutledge, James T.; Lee, Richard C.; Guyer, Robert A.; Johnson, Paul A.

    2012-07-05

    The key to safe design of critical facilities (strong ground motion in low velocity materials such as soils). Current approaches are predictions from measurements of the elastic non-linear properties of boreholes samples. Need for in-situ, local and complete determination of non-linear properties of soil, rock in response to high-strain motion.

  4. The analysis of in situ and retrieved aerosol properties measured during three airborne field campaigns

    NASA Astrophysics Data System (ADS)

    Corr, Chelsea A.

    Aerosols can directly influence climate, visibility, and photochemistry by scattering and absorbing solar radiation. Aerosol chemical and physical properties determine how efficiently a particle scatters and/or absorbs incoming short-wave solar radiation. Because many types of aerosol can act as nuclei for cloud droplets (CCN) and a smaller population of airborne particles facilitate ice crystal formation (IN), aerosols can also alter cloud-radiation interactions which have subsequent impacts on climate. Thus aerosol properties determine the magnitude and sign of both the direct and indirect impacts of aerosols on radiation-dependent Earth System processes. This dissertation will fill some gaps in our understanding of the role of aerosol properties on aerosol absorption and cloud formation. Specifically, the impact of aerosol oxidation on aerosol spectral (350nm < lambda< 500nm) absorption was examined for two biomass burning plumes intercepted by the NASA DC-S aircraft during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) mission in Spring and Summer 2008. Spectral aerosol single scattering albedo (SSA) retrieved using actinic flux measured aboard the NASA DC-8 was used to calculate the aerosol absorption Angstrom exponents (AAE) for a 6-day-old plume on April 17 th and a 3-hour old plume on June 29th. Higher AAE values for the April 17th plume (6.78+/-0.38) indicate absorption by aerosol was enhanced in the ultraviolet relative to the visible portion of the short-wave spectrum in the older plume compared to the fresher plume (AAE= 3.34 0.11). These differences were largely attributed to the greater oxidation of the organic aerosol in the April 17th plume which can arise either from the aging of primary organic aerosol or the formation of spectrally-absorbing secondary organic aerosol. The validity of the actinic flux retrievals used above were also evaluated in this work by the comparison of SSA retrieved using

  5. Cooling crystallization experiments observed by in situ scanning force microscopy

    NASA Astrophysics Data System (ADS)

    Kipp, S.; Lacmann, R.

    1996-03-01

    The change in surface morphology of potassium nitrate and potassium alum has been studied in situ by means of scanning force microscopy. The supersaturation and undersaturation were varied in a cooling crystallizer under flow conditions. To keep the crystal growth rate of potassium nitrate low, the specific additive DOW FAX 3B2 had been used in different concentrations. The crystal growth rate of both systems could be determined and the growth and dissolution surface morphologies of potassium alum exhibited structures similar to those of microscopic measurements.

  6. In Situ Airborne Instrumentation: Addressing and Solving Measurement Problems in Ice Clouds

    SciTech Connect

    Baumgardner, Darrel; Kok, Greg; Avallone, L.; Bansemer, A.; Borrmann, S.; Brown, P.; Bundke, U.; Chuang, P. Y.; Cziczo, D.; Field, P.; Gallagher, M.; Gayet, J. -F.; Korolev, A.; Kraemer, M.; McFarquhar, G.; Mertes, S.; Moehler, O.; Lance, S.; Lawson, P.; Petters, M. D.; Pratt, K.; Roberts, G.; Rogers, D.; Stetzer, O.; Stith, J.; Strapp, W.; Twohy, C.; Wendisch, M.

    2012-02-01

    A meeting of 31 international experts on in situ measurements from aircraft was held to identify unresolved questions concerning ice formation and evolution in ice clouds, assess the current state of instrumentation that can address these problems, introduce emerging technology that may overcome current measurement issues and recommend future courses of action that can improve our understanding of ice cloud microphysical processes and their impact on the environment. The meeting proceedings and outcome has been described in detail in a manuscript submitted to the Bulletin of the American Meteorological Society (BAMS) on March 24, 2011. This paper is currently under review. The remainder of this summary, in the following pages, is the text of the BAMS article. A technical note that will be published by the National Center for Atmospheric Research is currently underway and is expected to be published before the end of the year.

  7. In Situ Airborne Instrumentation: Addressing and Solving Measurement Problems in Ice Clouds

    DOE PAGES

    Baumgardner, Darrel; Kok, Greg; Avallone, L.; Bansemer, A.; Borrmann, S.; Brown, P.; Bundke, U.; Chuang, P. Y.; Cziczo, D.; Field, P.; et al

    2012-02-01

    A meeting of 31 international experts on in situ measurements from aircraft was held to identify unresolved questions concerning ice formation and evolution in ice clouds, assess the current state of instrumentation that can address these problems, introduce emerging technology that may overcome current measurement issues and recommend future courses of action that can improve our understanding of ice cloud microphysical processes and their impact on the environment. The meeting proceedings and outcome has been described in detail in a manuscript submitted to the Bulletin of the American Meteorological Society (BAMS) on March 24, 2011. This paper is currently undermore » review. The remainder of this summary, in the following pages, is the text of the BAMS article. A technical note that will be published by the National Center for Atmospheric Research is currently underway and is expected to be published before the end of the year.« less

  8. In situ observations of bifurcation of equatorial ionospheric plasma depletions

    SciTech Connect

    Aggson, T.L.; Pfaff, R.F.; Maynard, N.C.

    1996-03-01

    Vector electric field measurements from the San Marco D satellite are utilized to investigate the bifurcation of ionospheric plasma depletions (sometimes called {open_quotes}bubbles{close_quotes}) associated with nightside equatorial spread F. These depletions are identified by enhanced upward ExB convection in depleted plasma density channels in the nighttime equatorial ionosphere. The in situ determination of the bifurcation process is based on dc electric field measurements of the bipolar variation in the zonal flow, westward and eastward, as the eastbound satellite crosses isolated signatures of updrafting plasma depletion regions. The authors also present data in which more complicated regions of zonal velocity variations appear as the possible result of multiple bifurcations of updrafting equatorial plasma bubbles. 10 refs., 7 fig.

  9. Airborne observations of vegetation and implications for biogenic emission characterization.

    PubMed

    Hawes, Amy K; Solomon, Susan; Portmann, Robert W; Daniel, John S; Langford, Andrew O; Miller, H LeRoy; Eubank, Charles S; Goldan, Paul; Wiedinmyer, Christine; Atlas, Elliot; Hansel, Armin; Wisthaler, Armin

    2003-12-01

    Measuring hydrocarbons from aircraft represents one way to infer biogenic emissions at the surface. The focus of this paper is to show that complementary remote sensing information can be provided by optical measurements of a vegetation index, which is readily measured with high temporal coverage using reflectance data. We examine the similarities between the vegetation index and in situ measurements of the chemicals isoprene, methacrolein, and alpha-pinene to estimate whether the temporal behavior of the in situ measurements of these chemicals could be better understood by the addition of the vegetation index. Data were compared for flights conducted around Houston in August and September 2000. The three independent sets of chemical measurements examined correspond reasonably well with the vegetation index curves for the majority of flight days. While low values of the vegetation index always correspond to low values of the in situ chemical measurements, high values of the index correspond to both high and low values of the chemical measurements. In this sense it represents an upper limit when compared with in situ data (assuming the calibration constant is adequately chosen). This result suggests that while the vegetation index cannot represent a purely predictive quantity for the in situ measurements, it represents a complementary measurement that can be useful in understanding comparisons of various in situ observations, particularly when these observations occur with relatively low temporal frequency. In situ isoprene measurements and the vegetation index were also compared to an isoprene emission inventory to provide additional insight on broad issues relating to the use of vegetation indices in emission database development.

  10. Airborne vacuum ultraviolet resonance fluorescence instrument for in situ measurement of CO

    NASA Astrophysics Data System (ADS)

    Takegawa, N.; Kita, K.; Kondo, Y.; Matsumi, Y.; Parrish, D. D.; Holloway, J. S.; Koike, M.; Miyazaki, Y.; Toriyama, N.; Kawakami, S.; Ogawa, T.

    2001-10-01

    An airborne instrument for fast-response, high-precision measurement of tropospheric carbon monoxide (CO) was developed using a vacuum ultraviolet (VUV) resonance fluorescence technique. The excitation radiation is obtained by a DC discharge CO resonance lamp combined with an optical filter for the CO fourth positive band emission around 150 nm. The optical filter consists of a VUV monochromator and a crystalline quartz window (<147-nm cutoff). The crystalline quartz window ensures a sharp discrimination against wavelengths below 135.7 nm that yield a positive interference from water vapor. Laboratory tests showed that the optical system achieved a precision of 1.1 parts per billion by volume (ppbv) at a CO concentration of 100 ppbv for a 1-s integration period, and the flow system provided a response time (1/e time constant) of ˜2 s. The aircraft measurement campaign Biomass Burning and Lightning Experiment-phase B (BIBLE-B) was conducted between August and September 1999 over the western Pacific and Australia. The flight data obtained during this campaign were used to demonstrate the high precision and fast response of the instrument. An intercomparison of the VUV CO measurement and a gas chromatographic CO measurement was conducted during BIBLE-B. Overall, these two independent measurements showed good agreement, within the experimental uncertainties.

  11. Comparisons of Arctic In-Situ Snow and Ice Data with Airborne Passive Microwave Measurements

    NASA Technical Reports Server (NTRS)

    Markus, T.; Cavalien, D. J.; Gasiewski, A.; Sturm, M.; Klein, M.; Maslanik, J.; Stroeve, J.; Heinrichs, J.; Holmgren, J.; Irisov, V.

    2004-01-01

    As part of the AMSR-E sea ice validation campaign in March 2003, aircraft flights over the Arctic sea ice were coordinated with ground measurements of snow and sea ice properties. The surface-based measurements were in the vicinity of Barrow, AK, and at a Navy ice camp located in the Beaufort Sea. The NASA P-3 aircraft was equipped with the NOAA ETL PSR microwave radiometer that has the same frequencies as the AMSR-E sensor. The goal was to validate the standard AMSR-E products ice temperature and snow depth on sea ice. Ground measurements are the only way to validate these parameters. The higher spatial resolution of the PSR instrument (between 30 and 500 m, depending on altitude) enables a better comparison between ground measurements and microwave data because of the expected smaller spatial variability. Maps of PSR data can then be used for further down-scaling to AMSR-E pixel areas. Initial results show a good qualitative agreement between the in-situ snow depths and the PSR data. Detailed studies are underway and latest results will be presented.

  12. Airborne In-Situ Trace Gas Measurements of Multiple Wildfires in California (2013-2014)

    NASA Astrophysics Data System (ADS)

    Iraci, L. T.; Yates, E. L.; Tanaka, T.; Roby, M.; Gore, W.; Clements, C. B.; Lareau, N.; Ambrosia, V. G.; Quayle, B.; Schroeder, W.

    2014-12-01

    Biomass burning emissions are an important source of a wide range of trace gases and particles that can impact local, regional and global air quality, climate forcing, biogeochemical cycles and human health. In the western US, wildfires dominate over prescribed fires, contributing to atmospheric trace gas budgets and regional and local air pollution. Limited sampling of emissions from wildfires means western US emission estimates rely largely on data from prescribed fires, which may not be a suitable proxy for wildfire emissions. We report here in-situ measurements of carbon dioxide, methane, ozone and water vapor from the plumes of a variety of wildfires sampled in California in the fire seasons of 2013 and 2014. Included in the analysis are the Rim Fire (August - October 2013, near Yosemite National Park), the Morgan Fire (September 2013, near Clayton, CA), and the El Portal Fire (July - August 2014, in Yosemite National Park), among others. When possible, fires were sampled on multiple days. Emission ratios and estimated emission factors will be presented and discussed in the context of fuel composition, plume structure, and fire phase. Correlations of plume chemical composition to MODIS/VIIRS Fire Radiative Power (FRP) and other remote sensing information will be explored. Furthermore, the role of plumes in delivery of enhanced ozone concentrations to downwind municipalities will be discussed.

  13. Vertical distribution of aerosol number concentration in the troposphere over Siberia derived from airborne in-situ measurements

    NASA Astrophysics Data System (ADS)

    Arshinov, Mikhail Yu.; Belan, Boris D.; Paris, Jean-Daniel; Machida, Toshinobu; Kozlov, Alexandr; Malyskin, Sergei; Simonenkov, Denis; Davydov, Denis; Fofonov, Alexandr

    2016-04-01

    Knowledge of the vertical distribution of aerosols particles is very important when estimating aerosol radiative effects. To date there are a lot of research programs aimed to study aerosol vertical distribution, but only a few ones exist in such insufficiently explored region as Siberia. Monthly research flights and several extensive airborne campaigns carried out in recent years in Siberian troposphere allowed the vertical distribution of aerosol number concentration to be summarized. In-situ aerosol measurements were performed in a wide range of particle sizes by means of improved version of the Novosibirsk-type diffusional particle sizer and GRIMM aerosol spectrometer Model 1.109. The data on aerosol vertical distribution enabled input parameters for the empirical equation of Jaenicke (1993) to be derived for Siberian troposphere up to 7 km. Vertical distributions of aerosol number concentration in different size ranges averaged for the main seasons of the year will be presented. This work was supported by Interdisciplinary integration projects of the Siberian Branch of the Russian Academy of Science No. 35, No. 70 and No. 131; the Branch of Geology, Geophysics and Mining Sciences of RAS (Program No. 5); and Russian Foundation for Basic Research (grant No. 14-05-00526). Jaenicke R. Tropospheric aerosols, in Aerosol-Cloud-Climate Interactions, edited by P.V. Hobs. -Academic Press, San Diego, CA, 1993.- P. 1-31.

  14. SOFIA's Choice: Scheduling Observations for an Airborne Observatory

    NASA Technical Reports Server (NTRS)

    Frank, Jeremy; Kurklu, Elif; Koga, Dennis (Technical Monitor)

    2002-01-01

    We describe the problem of scheduling observations for an airborne observatory. The problem is more complex than traditional scheduling problems in that it incorporates complex constraints relating the feasibility of an astronomical observation to the position and time of a mobile observatory, as well as traditional temporal constraints and optimization criteria. We describe the problem, its proposed solution and the empirical validation of that solution.

  15. AASE-2 In-Situ Tracer Correlations of Methane Nitrous Oxide and Ozone as Observed Aboard the DC-8

    NASA Technical Reports Server (NTRS)

    Collins, J. E., Jr.; Sachse, G. W.; Anderson, B. E.; Weinheimer, A. J.; Walgea, J. G.; Ridley, B. A.

    1993-01-01

    We report in situ stratospheric measurements of CH4, N2O, and O3 obtained aboard the NASA DC-8 during the January-March 1992 Airborne Arctic Stratospheric Expedition II field campaign. These data demonstrate a strong linear correlation between N2O and CH4 in the lower stratosphere thus indicating that both species are effective tracers of stratospheric air motion. Measurements of both species on constant geometric height surfaces indicate that significant subsidence of the arctic stratospheric air mass occurred at DC-8 altitudes over the course of the AASE-II expedition. In addition, a widespread reduction in O3 mixing ratios (up to 20%) relative to these conserved tracers was also observed in the lower stratosphere in March a compared to January and February results.

  16. AASE-2 in-situ tracer correlations of methane, nitrous oxide, and ozone as observed aboard the DC-8

    NASA Technical Reports Server (NTRS)

    Collins, J. E., Jr.; Sachse, G. W.; Anderson, B. E.; Weinheimer, A. J.; Walega, J. G.; Ridley, B. A.

    1993-01-01

    We report in situ stratospheric measurements of CH4, N2O, and O3 obtained aboard the NASA DC-8 during the January-March 1992 Airborne Arctic Stratospheric Expedition 2 field campaign. These data demonstrate a strong linear correlation between N2O and CH4 in the lower stratosphere thus indicating that both species are effective tracers of stratospheric air motion. Measurements of both species on constant geometric height surfaces indicate that significant subsidence of the arctic stratospheric air mass occurred at DC-8 altitudes over the course of the AASE-2 expedition. In addition, a widespread reduction in O3 mixing ratios (up to 20%) relative to these conserved tracers was also observed in the lower stratosphere in March as compared to January and February results.

  17. Interpretation of TOMS Observations of Tropical Tropospheric Ozone with a Global Model and In Situ Observations

    NASA Technical Reports Server (NTRS)

    Martin, Randall V.; Jacob, Daniel J.; Logan, Jennifer A.; Bey, Isabelle; Yantosca, Robert M.; Staudt, Amanda C.; Fiore, Arlene M.; Duncan, Bryan N.; Liu, Hongyu; Ginoux, Paul

    2004-01-01

    We interpret the distribution of tropical tropospheric ozone columns (TTOCs) from the Total Ozone Mapping Spectrometer (TOMS) by using a global three-dimensional model of tropospheric chemistry (GEOS-CHEM) and additional information from in situ observations. The GEOS-CHEM TTOCs capture 44% of the variance of monthly mean TOMS TTOCs from the convective cloud differential method (CCD) with no global bias. Major discrepancies are found over northern Africa and south Asia where the TOMS TTOCs do not capture the seasonal enhancements from biomass burning found in the model and in aircraft observations. A characteristic feature of these northern topical enhancements, in contrast to southern tropical enhancements, is that they are driven by the lower troposphere where the sensitivity of TOMS is poor due to Rayleigh scattering. We develop an efficiency correction to the TOMS retrieval algorithm that accounts for the variability of ozone in the lower troposphere. This efficiency correction increases TTOC's over biomass burning regions by 3-5 Dobson units (DU) and decreases them by 2-5 DU over oceanic regions, improving the agreement between CCD TTOCs and in situ observations. Applying the correction to CCD TTOCs reduces by approximately DU the magnitude of the "tropical Atlantic paradox" [Thompson et al, 2000], i.e. the presence of a TTOC enhancement over the southern tropical Atlantic during the northern African biomass burning season in December-February. We reproduce the remainder of the paradox in the model and explain it by the combination of upper tropospheric ozone production from lightning NOx, peristent subsidence over the southern tropical Atlantic as part of the Walker circulation, and cross-equatorial transport of upper tropospheric ozone from northern midlatitudes in the African "westerly duct." These processes in the model can also account for the observed 13-17 DU persistent wave-1 pattern in TTOCs with a maximum above the tropical Atlantic and a minimum

  18. An assessment of IceBridge airborne data quality over Arctic sea ice via comparison with in situ measurements gathered in the Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Newman, T.; Farrell, S. L.; Richter-Menge, J.; Connor, L. N.; Kurtz, N. T.; Elder, B. C.

    2012-12-01

    are compared with an independent estimate of snow depth provided via the combination of Ku-band radar and ATM data. The direct comparison between the radar-derived snow depths and those measured in situ, allows the accuracy of the airborne data to be assessed with respect to the ice types present at the survey site. Combining knowledge of snow depth with sea ice freeboard, derived from the ATM data, we estimate sea ice thickness. We categorize sea ice thickness uncertainty as a function of ice type via one-on-one comparison with the field measurements. Finally, our data were corrected for ice drift and interpreted within the context of the ice surface morphology based on the DMS imagery.

  19. CBSIT 2009: Airborne Validation of Envisat Radar Altimetry and In Situ Ice Camp Measurements Over Arctic Sea Ice

    NASA Technical Reports Server (NTRS)

    Connor, Laurence; Farrell, Sinead; McAdoo, David; Krabill, William; Laxon, Seymour; Richter-Menge, Jacqueline; Markus, Thorsten

    2010-01-01

    with (1) Envisat RA-2 returns retracked optimally for sea ice and (2) in situ measurements of sea ice thickness and snow depth gathered from ice camp surveys. Particular attention is given to lead identification and classification using the continuous photo-imaging system along the Envisat underflight as well as the performance of the snow radar over the ice camp survey lines.

  20. A Rosetta Stone for in situ Observations of Magnetic Reconnection

    NASA Astrophysics Data System (ADS)

    Scudder, J. D.; Daughton, W. S.; Karimabadi, H.; Roytershteyn, V.

    2015-12-01

    Local conditions that constrain the physics of magnetic reconnection in space in 3D will be discussed, including those observable conditions presently used and new ones that enhance experimental closure. Three classes of tests will be discussed: i) proxies for unmeasurable theoretical properties II) observable properties satisfied by all layers that pass mass flux, including those of the reconnection layer, and (iii) observable kinetic tests that are increasingly peculiar to collisionless magnetic reconnection. A Rosetta Stone of state of the art observables will be proposed, including proxies for unmeasurable theoretical local rate of frozen flux violation and measures of the significance of frozen flux encountered. A suite of kinetic observables involving properties peculiar to electrons will also be demonstrated as promising litmus tests for certifying sites of collisionless magnetic reconnection.

  1. In situ observations of wave-induced sea ice breakup

    NASA Astrophysics Data System (ADS)

    Kohout, A. L.; Williams, M. J. M.; Toyota, T.; Lieser, J.; Hutchings, J.

    2016-09-01

    Ocean waves can propagate hundreds of kilometers into sea ice, leaving behind a wake of broken ice floes. Three floe breakup events were observed during the second Sea Ice Physics and Ecosystem Experiment (SIPEX-2). We show that the three breakup events were likely influenced by ocean waves. We compare the observations to a wave induced floe breakup model which includes an empirical wave attenuation model, and show that the model underestimates the extent of floe breaking for long period waves.

  2. Advancing in-situ modeling of ICMEs: Insights from remote observations and simulations

    NASA Astrophysics Data System (ADS)

    Jensen, E. A.; Mulligan, T.; Reinard, A. A.; Lynch, B. J.

    2011-12-01

    One of the underlying problems in the investigation of CME genesis and evolution is relating remote- sensing observations of coronal mass ejections (CMEs) to in-situ observations of interplanetary CMEs (ICMEs). Typically, the global structure of a CME projected onto the plane of the sky is obtained through remote-sensing, while local, yet highly-quantitative measurements of an ICME are made in situ along a spacecraft trajectory. Modeling the structure of these observations at the Sun and in situ has begun to bridge the gap between these vastly different types of observations, yet there is still a long way to go. Remote sensing observations and MHD simulations indicate we need to understand ICMEs in their entirety, including the various internal substructures in order to make comparisons between line-of-sight and in situ observations. This requires advancing ICME modeling beyond the flux rope boundaries. We have addressed this difficulty by developing a Delaunay triangulation method to combine multispacecraft in-situ observations to infer a more global structure of ICMEs in the plane of the spacecraft observations. We present a description of these techniques and a comparison with data.

  3. Husbandry Trace Gas Emissions from a Dairy Complex By Mobile in Situ and Airborne and Spaceborne Remote Sensing: A Comex Campaign Focus

    NASA Astrophysics Data System (ADS)

    Leifer, I.; Tratt, D. M.; Bovensmann, H.; Buckland, K. N.; Burrows, J. P.; Frash, J.; Gerilowski, K.; Iraci, L. T.; Johnson, P. D.; Kolyer, R.; Krautwurst, S.; Krings, T.; Leen, J. B.; Hu, C.; Melton, C.; Vigil, S. A.; Yates, E. L.; Zhang, M.

    2014-12-01

    Recent field study reviews on the greenhouse gas methane (CH4) found significant underestimation from fossil fuel industry and husbandry. The 2014 COMEX campaign seeks to develop methods to derive CH4 and carbon dioxide (CO2) from remote sensing data by combining hyperspectral imaging (HSI) and non-imaging spectroscopy (NIS) with in situ airborne and surface data. COMEX leverages synergies between high spatial resolution HSI column abundance maps and moderate spectral/spatial resolution NIS. Airborne husbandry data were collected for the Chino dairy complex (East Los Angeles Basin) by NIS-MAMAP, HSI-Mako thermal-infrared (TIR); AVIRIS NG shortwave IR (SWIR), with in situ surface mobile-AMOG Surveyor (AutoMObile greenhouse Gas)-and airborne in situ from a Twin Otter and the AlphaJet. AMOG Surveyor uses in situ Integrated Cavity Off Axis Spectroscopy (OA-ICOS) to measure CH4, CO2, H2O, H2S and NH3 at 5-10 Hz, 2D winds, and thermal anomaly in an adapted commuter car. OA-ICOS provides high precision and accuracy with excellent stability. NH3 and CH4 emissions were correlated at dairy size-scales but not sub-dairy scales in surface and Mako data, showing fine-scale structure and large variations between the numerous dairies in the complex (herd ~200,000-250,000) embedded in an urban setting. Emissions hotspots were consistent between surface and airborne surveys. In June, surface and MAMAP data showed a weak overall plume, while surface and Mako data showed a stronger plume in late (hotter) July. Multiple surface plume transects using NH3 fingerprinting showed East and then NE advection out of the LA Basin consistent with airborne data. Long-term trends were investigated in satellite data. This study shows the value of synergistically combined NH3 and CH4 remote sensing data to the task of CH4 source attribution using airborne and space-based remote sensing (IASI for NH3) and top of atmosphere sensitivity calculations for Sentinel V and Carbon Sat (CH4).

  4. In situ observation of oscillatory growth of bismuth nanoparticles.

    PubMed

    Xin, Huolin L; Zheng, Haimei

    2012-03-14

    We study the growth of Bi nanoparticles in an engineered precursor-scarce environment in a liquid cell at an elevated temperature (180 °C) using transmission electron microscopy. Observation reveals dynamics of oscillatory growth of individual nanoparticles, pairwise Ostwald ripening and anti-Ostwald ripening and a global collective oscillation. The experimental results suggest a mass-transport zone is present around each particle, which couples to the observed growth kinetics. This study shed light on a new route for system engineering to reverse particle coursing by Ostwald ripening.

  5. Utilization of Airborne and in Situ Data Obtained in SGP99, SMEX02, CLASIC and SMAPVEX08 Field Campaigns for SMAP Soil Moisture Algorithm Development and Validation

    NASA Technical Reports Server (NTRS)

    Colliander, Andreas; Chan, Steven; Yueh, Simon; Cosh, Michael; Bindlish, Rajat; Jackson, Tom; Njoku, Eni

    2010-01-01

    Field experiment data sets that include coincident remote sensing measurements and in situ sampling will be valuable in the development and validation of the soil moisture algorithms of the NASA's future SMAP (Soil Moisture Active and Passive) mission. This paper presents an overview of the field experiment data collected from SGP99, SMEX02, CLASIC and SMAPVEX08 campaigns. Common in these campaigns were observations of the airborne PALS (Passive and Active L- and S-band) instrument, which was developed to acquire radar and radiometer measurements at low frequencies. The combined set of the PALS measurements and ground truth obtained from all these campaigns was under study. The investigation shows that the data set contains a range of soil moisture values collected under a limited number of conditions. The quality of both PALS and ground truth data meets the needs of the SMAP algorithm development and validation. The data set has already made significant impact on the science behind SMAP mission. The areas where complementing of the data would be most beneficial are also discussed.

  6. Airborne aerosol in situ measurements during TCAP: A closure study of total scattering

    DOE PAGES

    Kassianov, Evgueni; Sedlacek, Arthur; Berg, Larry K.; Pekour, Mikhail; Barnard, James; Chand, Duli; Flynn, Connor; Ovchinnikov, Mikhail; Schmid, Beat; Shilling, John; et al

    2015-07-31

    We present a framework for calculating the total scattering of both non-absorbing and absorbing aerosol at ambient conditions from aircraft data. Our framework is developed emphasizing the explicit use of chemical composition data for estimating the complex refractive index (RI) of particles, and thus obtaining improved ambient size spectra derived from Optical Particle Counter (OPC) measurements. The feasibility of our framework for improved calculations of total scattering is demonstrated using three types of data collected by the U.S. Department of Energy’s (DOE) aircraft during the Two-Column Aerosol Project (TCAP). Namely, these data types are: (1) size distributions measured by amore » suite of OPC’s; (2) chemical composition data measured by an Aerosol Mass Spectrometer and a Single Particle Soot Photometer; and (3) the dry total scattering coefficient measured by a integrating nephelometer and scattering enhancement factor measured with a humidification system. We demonstrate that good agreement (~10%) between the observed and calculated scattering can be obtained under ambient conditions (RH < 80%) by applying chemical composition data for the RI-based correction of the OPC-derived size spectra. We also demonstrate that ignoring the RI-based correction or using non-representative RI values can cause a substantial underestimation (~40%) or overestimation (~35%) of the calculated scattering, respectively.« less

  7. Airborne aerosol in situ measurements during TCAP: A closure study of total scattering

    SciTech Connect

    Kassianov, Evgueni; Sedlacek, Arthur; Berg, Larry K.; Pekour, Mikhail; Barnard, James; Chand, Duli; Flynn, Connor; Ovchinnikov, Mikhail; Schmid, Beat; Shilling, John; Tomlinson, Jason; Fast, Jerome

    2015-07-31

    We present a framework for calculating the total scattering of both non-absorbing and absorbing aerosol at ambient conditions from aircraft data. Our framework is developed emphasizing the explicit use of chemical composition data for estimating the complex refractive index (RI) of particles, and thus obtaining improved ambient size spectra derived from Optical Particle Counter (OPC) measurements. The feasibility of our framework for improved calculations of total scattering is demonstrated using three types of data collected by the U.S. Department of Energy’s (DOE) aircraft during the Two-Column Aerosol Project (TCAP). Namely, these data types are: (1) size distributions measured by a suite of OPC’s; (2) chemical composition data measured by an Aerosol Mass Spectrometer and a Single Particle Soot Photometer; and (3) the dry total scattering coefficient measured by a integrating nephelometer and scattering enhancement factor measured with a humidification system. We demonstrate that good agreement (~10%) between the observed and calculated scattering can be obtained under ambient conditions (RH < 80%) by applying chemical composition data for the RI-based correction of the OPC-derived size spectra. We also demonstrate that ignoring the RI-based correction or using non-representative RI values can cause a substantial underestimation (~40%) or overestimation (~35%) of the calculated scattering, respectively.

  8. Passive microwave in situ observations of Winter Weddell Sea Ica

    NASA Astrophysics Data System (ADS)

    Comiso, J. C.; Grenfell, T. C.; Bell, D. L.; Lange, M. A.; Ackley, S. F.

    1989-08-01

    The microwave radiative characteristics of Antarctic sea ice during a winter period were investigated continuously from R/V Polarstern during the 1986 Winter Weddell Sea Project while the ship went through about 3000 km of ice from the marginal ice zone to the coastal region and back. Radiometer measurements at 6, 10, 18, 37, and 90 GHz in vertical and horizontal polarizations were complemented by visual and video observations and measurements at 60 stations of ice thickness, salinity, temperature, snow cover, density, and other physical characteristics. Two distinct types of ice cover were observed in the marginal ice zone: small pancakes evenly distributed during the southbound leg, and ice bands with wet pancakes during the northbound leg. Other ice types observed were first-year ice covered by varying thicknesses and states of snow cover, and new and young ice found mainly in leads and polynyas. Analysis of the data shows a large variability in the multispectral microwave emissivities of these ice types, especially at 90 GHz. Over newly refrozen lead or polynya regions, several forms of new ice appear radiometrically distinct, while over thick consolidated ice with snow cover, the brightness temperatures observed at 90 GHz varied by as much as 100 K. Overall, however, at 18 GHz and lower frequencies, the emissivities of thick and cold first-year ice are relatively stable with standard deviations of about ±0.02. At the marginal ice zone, the emissivity of the ice cover is a lot less predictable and could cause large uncertainties in ice concentration estimates. The use of the 90-GHz channel in combination with a lower-frequency channel shows strong potential for more detailed characterization of the ice cover including the identification of various forms of new ice and the quantification of varying snow cover and roughness.

  9. Airborne Aerosol In situ Measurements during TCAP: A Closure Study of Total Scattering

    SciTech Connect

    Kassianov, Evgueni I.; Berg, Larry K.; Pekour, Mikhail S.; Flynn, Connor J.; Tomlinson, Jason M.; Chand, Duli; Shilling, John E.; Ovchinnikov, Mikhail; Barnard, James C.; Sedlacek, Art; Schmid, Beat

    2015-07-31

    We present here a framework for calculating the total scattering of both non-absorbing and absorbing aerosol at ambient conditions from aircraft data. The synergistically employed aircraft data involve aerosol microphysical, chemical, and optical components and ambient relative humidity measurements. Our framework is developed emphasizing the explicit use of the complementary chemical composition data for estimating the complex refractive index (RI) of particles, and thus obtaining improved ambient size spectra derived from Optical Particle Counter (OPC) measurements. The feasibility of our framework for improved calculations of total aerosol scattering is demonstrated for different ambient conditions with a wide range of relative humidities (from 5 to 80%) using three types of data collected by the U.S. Department of Energy (DOE) G-1 aircraft during the recent Two-Column Aerosol Project (TCAP). Namely, these three types of data employed are: (1) size distributions measured by an Ultra High Sensitivity Aerosol Spectrometer (UHSAS; 0.06-1 µm), a Passive Cavity Aerosol Spectrometer (PCASP; 0.1-3 µm) and a Cloud and Aerosol Spectrometer (CAS; 0.6- >10 µm), (2) chemical composition data measured by an Aerosol Mass Spectrometer (AMS; 0.06-0.6 µm) and a Single Particle Soot Photometer (SP2; 0.06-0.6 µm), and (3) the dry total scattering coefficient measured by a TSI integrating nephelometer at three wavelengths (0.45, 0.55, 0.7 µm) and scattering enhancement factor measured with a humidification system at three RHs (near 45%, 65% and 90%) at a single wavelength (0.525 µm). We demonstrate that good agreement (~10% on average) between the observed and calculated scattering at these three wavelengths can be obtained using the best available chemical composition data for the RI-based correction of the OPC-derived size spectra. We also demonstrate that ignoring the RI-based correction and using non-representative RI values can cause a substantial underestimation (~40

  10. In situ observations of interstellar plasma with Voyager 1.

    PubMed

    Gurnett, D A; Kurth, W S; Burlaga, L F; Ness, N F

    2013-09-27

    Launched over 35 years ago, Voyagers 1 and 2 are on an epic journey outward from the Sun to reach the boundary between the solar plasma and the much cooler interstellar medium. The boundary, called the heliopause, is expected to be marked by a large increase in plasma density, from about 0.002 per cubic centimeter (cm(-3)) in the outer heliosphere, to about 0.1 cm(-3) in the interstellar medium. On 9 April 2013, the Voyager 1 plasma wave instrument began detecting locally generated electron plasma oscillations at a frequency of about 2.6 kilohertz. This oscillation frequency corresponds to an electron density of about 0.08 cm(-3), very close to the value expected in the interstellar medium. These and other observations provide strong evidence that Voyager 1 has crossed the heliopause into the nearby interstellar plasma.

  11. In situ observations of mesoscale undercurrents off eastern Madagascar

    NASA Astrophysics Data System (ADS)

    Ponsoni, Leandro; Aguiar-Gonzalez, Borja; Maas, Leo; van Aken, Hendrik; Nauw, Janine; Ridderinkhof, Herman

    2015-04-01

    The South-West Indian Ocean (SWIO) presents one of the most intriguing western boundary regions of all subtropical gyres. Unlike other gyres, in the SWIO the Madagascar island imposes a physical barrier to the westward flowing South Equatorial Current (SEC), which reaches the Madagascar coast between 17°S and 20°S. At this location, the SEC bifurcates into two branches: the poleward branch feeds into the East Madagascar Current (EMC), which further south will feed the Agulhas Current (AC); on the other hand, the poleward branch feeds into the North Madagascar Current (NMC), which turns around Cape Amber, at the northern tip of Madagascar, and continues westward towards the east coast of Africa. Besides the patterns of the boundary currents described above, undercurrents flowing opposite and beneath the mentioned surface currents are also reported to occur: the equatorward East Madagascar Undercurrent (EMUC) and the poleward North Madagascar Undercurrent (NMUC). This work is based on field studies of both undercurrents. We deployed a cross-slope array of five moorings at 23°S off eastern Madagascar, which was maintained from late 2010 till early 2013 (~2.5 years). A total of 6 Acoustic Doppler Current Profiles and 10 Recording Current Meters were coupled to the moorings. Direct measurements were made from near surface (~50 m) to deep in the water column (~4000 m). The observations reveal a recurring equatorward EMUC with its core hugging the continental slope, at a depth of 1260 m and at an approximate distance of 29 km from the coast. The core velocity has a mean value of 4.1 (±6.3) cm s-1, while maximum speeds reach up to 20 cm -1. The volume transport is estimated to be 1.33 (±1.14) Sv with maxima up to 6 Sv. At the northern tip of Madagascar, off Cape Ambar, we present the first observational evidence of a poleward NMUC. These results are based on a hydrographic cruise (March 2001), where vertical profiles of velocity were sampled across the continental

  12. In Situ Observational Constraints on GIA in Antarctica

    NASA Astrophysics Data System (ADS)

    Wilson, T. J.; Bevis, M. G.; Kendrick, E. C.; Konfal, S.; Dalziel, I. W.; Smalley, R.; Willis, M. J.; Wiens, D. A.; Heeszel, D. S.

    2012-12-01

    Geodetic and seismologic data sets have been acquired across a significant portion of Antarctica through deployment of autonomous, remote instrumentation by the Antarctic Network (ANET) project of the Polar Earth Observing Network (POLENET). Continuous GPS measurements of bedrock crustal motions are yielding a synoptic picture of vertical and horizontal crustal motion patterns from the Transantarctic Mountains to the Ellsworth-Whitmore Mountains and Marie Byrd Land regions. Vertical motion patterns are broadly compatible with predictions from current GIA models, but the magnitudes of the vertical motions are substantially lower than predicted. Slower rates of uplift due to GIA can be attributed to factors including errors in ice history, a superposed solid earth response to modern ice mass change, and/or the influence of laterally varying earth properties on the GIA response. Patterns of horizontal motions measured by ANET show that the role of laterally varying earth rheology is extremely important in Antarctica. Crustal motion vectors are closely aligned and document motion from East toward West Antarctica, in contradiction to ice sheet reconstructions placing maximum LGM ice mass loss in West Antarctica and GIA models that predict motions in the opposite direction. When compared to earth structure mapped by seismology, the horizontal crustal motions are consistently near-perpendicular to the very strong gradient in crust and mantle properties, perhaps the first confirmation of predictions from modeling studies that horizontal motions can be deflected or even reversed where such a lateral earth property exists. Accurate GIA models for Antarctica clearly require a laterally-varying earth model and tuning based on these new GPS and seismological constraints.

  13. In Situ Observations of an Ionospheric Critical Velocity Experiment

    NASA Astrophysics Data System (ADS)

    Swenson, Charles Merrill

    1992-01-01

    The critical ionization velocity effect (CIV), proposed by Hannes Alfven, may play a major role in the formation, shaping, and distribution of matter in the universe. It is a mechanism whereby the kinetic energy of a neutral cloud relative to a magnetized plasma is used for self -ionization of the neutral cloud. The magnetized plasma through which the neutral cloud passes acts as a type of catalyst, promoting a reaction that would not otherwise occur. For the past 30 years the question of whether a magnetized plasma can act as such a catalyst for the ionization of a streaming gas has been studied in the laboratory where the basic concept has been proven correct. In this thesis we report on a set of rocket borne CIV experiments, CRIT I & II, which were conducted in the ionosphere with barium. We present measurements of the plasma density, electric fields, magnetic fields, energetic electrons, and energetic ions within the ionizing barium stream. Plasma density enhancements were observed and are shown to be signatures of a CIV process albeit one which is less efficient than theory suggests. Other signatures of CIV such as scattering and slowing of the newly created barium ions, heating of electrons, and the emission of an Alfven waves from the ionization region were also detected. We have found that waves within the region where CIV is active are not the classical lower hybrid waves as predicted by current theories. Since waves of some sort are required by all conceivable theories linking the beam energy to the electron gas, this result is quite important. Instead we find a low-frequency long-wavelength mode that is in resonance with the barium ion beam (omega ~ vec k cdotvec V_{ rm beam}). Through an interferometric analysis of the electric field data we show that the wave vector vec k of these waves is aligned with the barium beam (57^circ to vec B_0) while the electric field of the waves is almost perpendicular to vec B_0. Therefore, the wave appears to be a mixed

  14. In-situ Ground-Based and Airborne Formaldehyde Measurements in the Houston Area During TexAQS-II

    NASA Astrophysics Data System (ADS)

    Rappenglueck, B.; Byun, D.; Alvarez, S.; Buhr, M.; Coarfa, V.; Czader, B.; Dasgupta, P.; Estes, M.; Kim, S.; Leuchner, M.; Luke, W.; Shauck, M.; Zanin, G.

    2007-12-01

    Formaldehyde is considered to play a significant role in summertime photochemistry in the Houston area, in particular it is considered an important source for radicals. Secondary formation seems to be the most important fraction of ambient HCHO. Enhanced nighttime values may indicate primary sources. Potential sources may include mobile sources such as traffic exhaust, in particular not well maintained Diesel engines. Other possible sources may include point sources such as coffee roasting and flares from refineries. In this study we focused on the TexAQS-II continuous in-situ formaldehyde data set based on Hantzsch reaction which was obtained in the Ship Channel area (HRM3 and Lynchburg Ferry site) and at the Moody Tower for several weeks. We also include in-situ HCHO measurements obtained with the same technique aboard the Baylor aircraft during TexAQS-II flight missions. Formaldehyde data was compared to several trace gases that are supposed to be coemitted including CO (traffic), ethylene (flares), and SO2 (industry). In order to keep photochemical processes at a minimum special focus was on nighttime data. Case studies will be discussed where meteorological conditions including recirculation and boundary layer developments seem to play a major role in the redistribution of HCHO. Observations will be compared to CMAQ model studies.

  15. Applying Squeaky-Wheel Optimization Schedule Airborne Astronomy Observations

    NASA Technical Reports Server (NTRS)

    Frank, Jeremy; Kuerklue, Elif

    2004-01-01

    We apply the Squeaky Wheel Optimization (SWO) algorithm to the problem of scheduling astronomy observations for the Stratospheric Observatory for Infrared Astronomy, an airborne observatory. The problem contains complex constraints relating the feasibility of an astronomical observation to the position and time at which the observation begins, telescope elevation limits, special use airspace, and available fuel. Solving the problem requires making discrete choices (e.g. selection and sequencing of observations) and continuous ones (e.g. takeoff time and setting up observations by repositioning the aircraft). The problem also includes optimization criteria such as maximizing observing time while simultaneously minimizing total flight time. Previous approaches to the problem fail to scale when accounting for all constraints. We describe how to customize SWO to solve this problem, and show that it finds better flight plans, often with less computation time, than previous approaches.

  16. AVIATR—Aerial Vehicle for In-situ and Airborne Titan Reconnaissance. A Titan airplane mission concept

    NASA Astrophysics Data System (ADS)

    Barnes, Jason W.; Lemke, Lawrence; Foch, Rick; McKay, Christopher P.; Beyer, Ross A.; Radebaugh, Jani; Atkinson, David H.; Lorenz, Ralph D.; Le Mouélic, Stéphane; Rodriguez, Sebastien; Gundlach, Jay; Giannini, Francesco; Bain, Sean; Flasar, F. Michael; Hurford, Terry; Anderson, Carrie M.; Merrison, Jon; Ádámkovics, Máté; Kattenhorn, Simon A.; Mitchell, Jonathan; Burr, Devon M.; Colaprete, Anthony; Schaller, Emily; Friedson, A. James; Edgett, Kenneth S.; Coradini, Angioletta; Adriani, Alberto; Sayanagi, Kunio M.; Malaska, Michael J.; Morabito, David; Reh, Kim

    2012-03-01

    We describe a mission concept for a stand-alone Titan airplane mission: Aerial Vehicle for In-situ and Airborne Titan Reconnaissance (AVIATR). With independent delivery and direct-to-Earth communications, AVIATR could contribute to Titan science either alone or as part of a sustained Titan Exploration Program. As a focused mission, AVIATR as we have envisioned it would concentrate on the science that an airplane can do best: exploration of Titan's global diversity. We focus on surface geology/hydrology and lower-atmospheric structure and dynamics. With a carefully chosen set of seven instruments—2 near-IR cameras, 1 near-IR spectrometer, a RADAR altimeter, an atmospheric structure suite, a haze sensor, and a raindrop detector—AVIATR could accomplish a significant subset of the scientific objectives of the aerial element of flagship studies. The AVIATR spacecraft stack is composed of a Space Vehicle (SV) for cruise, an Entry Vehicle (EV) for entry and descent, and the Air Vehicle (AV) to fly in Titan's atmosphere. Using an Earth-Jupiter gravity assist trajectory delivers the spacecraft to Titan in 7.5 years, after which the AVIATR AV would operate for a 1-Earth-year nominal mission. We propose a novel `gravity battery' climb-then-glide strategy to store energy for optimal use during telecommunications sessions. We would optimize our science by using the flexibility of the airplane platform, generating context data and stereo pairs by flying and banking the AV instead of using gimbaled cameras. AVIATR would climb up to 14 km altitude and descend down to 3.5 km altitude once per Earth day, allowing for repeated atmospheric structure and wind measurements all over the globe. An initial Team-X run at JPL priced the AVIATR mission at FY10 715M based on the rules stipulated in the recent Discovery announcement of opportunity. Hence we find that a standalone Titan airplane mission can achieve important science building on Cassini's discoveries and can likely do so

  17. Predicting the aquatic stage sustainability of a restored backwater channel combining in-situ and airborne remotely sensed bathymetric models.

    NASA Astrophysics Data System (ADS)

    Jérôme, Lejot; Jérémie, Riquier; Hervé, Piégay

    2014-05-01

    As other large river floodplain worldwide, the floodplain of the Rhône has been deeply altered by human activities and infrastructures over the last centuries both in term of structure and functioning. An ambitious restoration plan of selected by-passed reaches has been implemented since 1999, in order to improve their ecological conditions. One of the main action aimed to increase the aquatic areas in floodplain channels (i.e. secondary channels, backwaters, …). In practice, fine and/or coarse alluvium were dredged, either locally or over the entire cut-off channel length. Sometimes the upstream or downstream alluvial plugs were also removed to reconnect the restored feature to the main channel. Such operation aims to restore forms and associated habitats of biotic communities, which are no more created or maintained by the river itself. In this context, assessing the sustainability of such restoration actions is a major issue. In this study, we focus on 1 of the 24 floodplain channels which have been restored along the Rhône River since 1999, the Malourdie channel (Chautagne reach, France). A monitoring of the geomorphologic evolution of the channel has been conducted during a decade to assess the aquatic stage sustainability of this former fully isolated channel, which has been restored as a backwater in 2004. Two main types of measures were performed: (a) water depth and fine sediment thickness were surveyed with an auger every 10 m along the channel centerline in average every year and a half allowing to establish an exponential decay model of terrestrialization rates through time; (b) three airborne campaigns (2006, 2007, 2012) by Ultra Aerial Vehicle (UAV) provided images from which bathymetry were inferred in combination with observed field measures. Coupling field and airborne models allows us to simulate different states of terrestrialization at the scale of the whole restore feature (e.g. 2020/2030/2050). Raw results indicate that terrestrialization

  18. Vertical mass impact and features of Saharan dust intrusions derived from ground-based remote sensing in synergy with airborne in-situ measurements

    NASA Astrophysics Data System (ADS)

    Córdoba-Jabonero, Carmen; Andrey-Andrés, Javier; Gómez, Laura; Adame, José Antonio; Sorribas, Mar; Navarro-Comas, Mónica; Puentedura, Olga; Cuevas, Emilio; Gil-Ojeda, Manuel

    2016-10-01

    A study of the vertical mass impact of Saharan dust intrusions is presented in this work. Simultaneous ground-based remote-sensing and airborne in-situ measurements performed during the AMISOC-TNF campaign over the Tenerife area (Canary Islands) in summertime from 01 July to 11 August 2013 were used for that purpose. A particular dusty (DD) case, associated to a progressively arriving dust intrusion lasting for two days on 31 July (weak incidence) and 01 August (strong incidence), is especially investigated. AERONET AOD and AEx values were ranging, respectively, from 0.2 to 1.4 and 0.35 to 0.05 along these two days. Vertical particle size distributions within fine and coarse modes (0.16-2.8 μm range) were obtained from aircraft aerosol spectrometer measurements. Extinction profiles and Lidar Ratio (LR) values were derived from MPLNET/Micro Pulse Lidar observations. MAXDOAS measurements were also used to retrieve the height-resolved aerosol extinction for evaluation purposes in comparison to Lidar-derived profiles. The synergy between Lidar observations and airborne measurements is established in terms of the Mass Extinction Efficiency (MEE) to calculate the vertical mass concentration of Saharan dust particles. Both the optical and microphysical profilings show dust particles mostly confined in a layer of 4.3 km thickness from 1.7 to 6 km height. LR ranged between 50 and 55 sr, typical values for Saharan dust particles. In addition, this 2-day dust event mostly affected the Free Troposphere (FT), being less intense in the Boundary Layer (BL). In particular, rather high Total Mass Concentrations (TMC) were found on the stronger DD day (01 August 2013): 124, 70 and 21 μg m-3 were estimated, respectively, at FT and BL altitudes and on the near-surface level. This dust impact was enhanced due to the increase of large particles affecting the FT, but also the BL, likely due to their gravitational settling. However, the use of an assumed averaged MEE value can be

  19. Vertical distribution of trace gas species in the troposphere over the south of West Siberia: comparison of airborne in situ measurements and satellite data

    NASA Astrophysics Data System (ADS)

    Belan, Boris D.; Arshinov, Mikhail Yu.; Belov, Vladimir V.; Gridnev, Yurii V.; Davydov, Denis K.; Machida, Toshinobu; Paris, Jean-Daniel; Nédélec, Philippe; Fofonov, Alexander V.

    2014-05-01

    A comparison of the vertical distributions of O3, CO, CO2 and CH4 derived from the airborne in situ measurements and satellite observations over the southern part of West Siberia is presented. In this study we used data of monthly research flights of 'Optik' TU-134 aircraft laboratory carried out from 2012 to 2013 and data retrieved from measurements of the Infrared Atmospheric Sounding Interferometer (IASI) instrument on-board the MetOp satellite. It was found that differences in ozone mixing ratios between the airborne and satellite data can vary from +3 to +18 ppb at 0.5 km AGL and form -8 to -37 ppb at 7 km AGL, and relative ones ranged from +8 to +30 % and from -12 to -88 %, respectively. Differences in CO concentrations varied from +32 to +103 ppb at 0.5 km height and from -18 to +23 ppb at 3 km. Relative differences were in the range from -4 to +48 % at 0.5 km and from -8 to +20 % at 7 km. The maximal difference in all CH4 profiles reached 150 ppb in the atmospheric boundary layer, and the minimal one was -10 ppb. The average relative difference varied between +2.8 and -0.5 %. The average difference in CO2 concentration lies within ±1.5 ppm, while individual profiles are incommensurable. Maximal and minimal differences during the all flights were observed in the atmospheric boundary layer (+10 and -12 ppm or +2.3 and -3.3%, respectively). In the free troposphere, relative difference decreased down to ±1.0%. This work was funded by Research funds for Global Environmental Monitoring in NIES (Japan), CNRS (France), the French Ministry of Foreign Affairs, CEA (France), Presidium of RAS (Program No. 4), Brunch of Geology, Geophysics and Mining Sciences of RAS (Program No. 5), Interdisciplinary integration projects of Siberian Branch of RAS (No. 35, No. 70, No. 131), Russian Foundation for Basic Research (grants No 14-05-00526, 14-05-00590).

  20. Airborne passive remote sensing of large-scale methane emissions from oil fields in California's San Joaquin Valley and validation by airborne in-situ measurements - Initial results from COMEX

    NASA Astrophysics Data System (ADS)

    Gerilowski, Konstantin; Krautwurst, Sven; Kolyer, Richard W.; Thompson, David R.; Jonsson, Haflidi; Krings, Thomas; Horstjann, Markus; Leifer, Ira; Eastwood, Michael; Green, Robert O.; Vigil, Sam; Schüttemeyer, Dirk; Fladeland, Matthew; Burrows, John P.; Bovensmann, Heinrich

    2015-04-01

    On several flights performed over the Kern River, Kern Front, and Poso Creek Oil Fields in California between June 3 and September 4, 2014, in the framework of the CO2 and MEthane Experiment (COMEX) - a NASA and ESA funded campaign in support of the HyspIRI and CarbonSat mission definition activities - the Methane Airborne MAPper (MAMAP) remote sensing instrument (operated by the University of Bremen in cooperation with the German Research Centre for Geosciences - GFZ) detected large-scale, high-concentration, methane plumes. MAMAP was installed for the flights aboard the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter aircraft, together with a Picarro fast in-situ greenhouse gas (GHG) analyzer (operated by the NASA Ames Research Center, ARC), a 5-hole turbulence probe and an atmospheric measurement package (operated by CIRPAS), measuring aerosols, temperature, dew-point, and other atmospheric parameters. Some of the flights were accompanied by the next generation of the Airborne Visible InfraRed Imaging Spectrometer (AVIRIS-NG), operated by the Jet Propulsion Laboratory (JPL), California Institute of Technology, installed aboard a second Twin Otter aircraft (operated by Twin Otter International). Data collected with the in-situ GHG analyzer were used for validation of the MAMAP and AVIRIS-NG remotely sensed data. The in-situ measurements were acquired in vertical cross sections of the discovered plumes at fixed distances downwind of the sources. Emission rates are estimated from both the remote and in-situ data using wind information from the turbulence probe together with ground-based wind data from the nearby airport. Remote sensing and in-situ data as well as initial flux estimates for selected flights will be presented.

  1. Interactions between Coronal Mass Ejections Viewed in Coordinated Imaging and In Situ Observations

    NASA Technical Reports Server (NTRS)

    Liu, Ying D.; Luhmann, Janet G.; Moestl, Christian; Martinez-Oliveros, Juan C.; Bale, Stewart D.; Lin, Robert P.; Harrison, Richard A.; Temmer, Manuela; Webb, David F.; Odstrcil, Dusan

    2013-01-01

    The successive coronal mass ejections (CMEs) from 2010 July 30 - August 1 present us the first opportunity to study CME-CME interactions with unprecedented heliospheric imaging and in situ observations from multiple vantage points. We describe two cases of CME interactions: merging of two CMEs launched close in time and overtaking of a preceding CME by a shock wave. The first two CMEs on August 1 interact close to the Sun and form a merged front, which then overtakes the July 30 CME near 1 AU, as revealed by wide-angle imaging observations. Connections between imaging observations and in situ signatures at 1 AU suggest that the merged front is a shock wave, followed by two ejecta observed at Wind which seem to have already merged. In situ measurements show that the CME from July 30 is being overtaken by the shock at 1 AU and is significantly compressed, accelerated and heated. The interaction between the preceding ejecta and shock also results in variations in the shock strength and structure on a global scale, as shown by widely separated in situ measurements from Wind and STEREO B. These results indicate important implications of CME-CME interactions for shock propagation, particle acceleration and space weather forecasting.

  2. In-situ observations of point-defect precipitation at dislocations in electron-irradiated silver

    SciTech Connect

    Jenkins, M.L.; Hardy, G.J.; Kirk, M.A.

    1986-09-01

    In-situ weak-beam observations of the development of electron irradiation damage at dislocations in silver are described. Dislocations constrict and promote in their vicinity the formation of stacking-fault tetrahedra. The possibility that these are of interstitial nature is discussed.

  3. In Situ Observation and Selective Electrochemical Deposition of Polypyrrole by Scanning Tunneling Microscope

    NASA Astrophysics Data System (ADS)

    Sasano, Kiyotaka; Nakamura, Kazunori; Kaneto, Keiichi

    1993-06-01

    Electrodeposition of polypyrrole and its selective deposition on a highly oriented pyrolytic graphite substrate was observed in situ by means of scanning tunneling microscope (STM) in an electrochemical cell. The results indicated that the STM can be used to manipulate the electrodeposition of conducting polymers.

  4. Quantifying Spatial and Seasonal Variability in Atmospheric Ammonia with In Situ and Space-Based Observations

    EPA Science Inventory

    Ammonia plays an important role in many biogeochemical processes, yet atmospheric mixing ratios arc not well known. Recently, methods have been developed for retrieving NH3 from space-based observations, but they have not been compared to in situ measurements. We have ...

  5. INTERACTIONS BETWEEN CORONAL MASS EJECTIONS VIEWED IN COORDINATED IMAGING AND IN SITU OBSERVATIONS

    SciTech Connect

    Liu, Ying D.; Luhmann, Janet G.; Moestl, Christian; Martinez-Oliveros, Juan C.; Bale, Stuart D.; Lin, Robert P.; Harrison, Richard A.; Temmer, Manuela; Webb, David F.; Odstrcil, Dusan

    2012-02-20

    The successive coronal mass ejections (CMEs) from 2010 July 30 to August 1 present us the first opportunity to study CME-CME interactions with unprecedented heliospheric imaging and in situ observations from multiple vantage points. We describe two cases of CME interactions: merging of two CMEs launched close in time and overtaking of a preceding CME by a shock wave. The first two CMEs on August 1 interact close to the Sun and form a merged front, which then overtakes the July 30 CME near 1 AU, as revealed by wide-angle imaging observations. Connections between imaging observations and in situ signatures at 1 AU suggest that the merged front is a shock wave, followed by two ejecta observed at Wind which seem to have already merged. In situ measurements show that the CME from July 30 is being overtaken by the shock at 1 AU and is significantly compressed, accelerated, and heated. The interaction between the preceding ejecta and shock also results in variations in the shock strength and structure on a global scale, as shown by widely separated in situ measurements from Wind and STEREO B. These results indicate important implications of CME-CME interactions for shock propagation, particle acceleration, and space weather forecasting.

  6. Under-canopy snow accumulation and ablation measured with airborne scanning LiDAR altimetry and in-situ instrumental measurements, southern Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Kirchner, P. B.; Bales, R. C.; Musselman, K. N.; Molotch, N. P.

    2012-12-01

    We investigated the influence of canopy on snow accumulation and melt in a mountain forest using paired snow on and snow off scanning LiDAR altimetry, synoptic measurement campaigns and in-situ time series data of snow depth, SWE, and radiation collected from the Kaweah River watershed, Sierra Nevada, California. Our analysis of forest cover classified by dominant species and 1 m2 grided mean under canopy snow accumulation calculated from airborne scanning LiDAR, demonstrate distinct relationships between forest class and under-canopy snow depth. The five forest types were selected from carefully prepared 1 m vegetation classifications and named for their dominant tree species, Giant Sequoia, Jeffrey Pine, White Fir, Red Fir, Sierra Lodgepole, Western White Pine, and Foxtail Pine. Sufficient LiDAR returns for calculating mean snow depth per m2 were available for 31 - 44% of the canopy covered area and demonstrate a reduction in snow depth of 12 - 24% from adjacent open areas. The coefficient of variation in snow depth under canopies ranged from 0.2 - 0.42 and generally decreased as elevation increased. Our analysis of snow density snows no statistical significance between snow under canopies and in the open at higher elevations with a weak significance for snow under canopies at lower elevations. Incident radiation measurements made at 15 minute intervals under forest canopies show an input of up to 150 w/m2 of thermal radiation from vegetation to the snow surface on forest plots. Snow accumulated on the mid to high elevation forested slopes of the Sierra Nevada represents the majority of winter snow storage. However snow estimates in forested environments demonstrate a high level of uncertainty due to the limited number of in-situ observations and the inability of most remote sensing platforms to retrieve reflectance under dense vegetation. Snow under forest canopies is strongly mediated by forest cover and decoupled from the processes that dictate accumulation

  7. Regional Scaling of Airborne Eddy Covariance Flux Observation

    NASA Astrophysics Data System (ADS)

    Sachs, T.; Serafimovich, A.; Metzger, S.; Kohnert, K.; Hartmann, J.

    2014-12-01

    The earth's surface is tightly coupled to the global climate system by the vertical exchange of energy and matter. Thus, to better understand and potentially predict changes to our climate system, it is critical to quantify the surface-atmosphere exchange of heat, water vapor, and greenhouse gases on climate-relevant spatial and temporal scales. Currently, most flux observations consist of ground-based, continuous but local measurements. These provide a good basis for temporal integration, but may not be representative of the larger regional context. This is particularly true for the Arctic, where site selection is additionally bound by logistical constraints, among others. Airborne measurements can overcome this limitation by covering distances of hundreds of kilometers over time periods of a few hours. The Airborne Measurements of Methane Fluxes (AIRMETH) campaigns are designed to quantitatively and spatially explicitly address this issue: The research aircraft POLAR 5 is used to acquire thousands of kilometers of eddy-covariance flux data. During the AIRMETH-2012 and AIRMETH-2013 campaigns we measured the turbulent exchange of energy, methane, and (in 2013) carbon dioxide over the North Slope of Alaska, USA, and the Mackenzie Delta, Canada. Here, we present the potential of environmental response functions (ERFs) for quantitatively linking flux observations to meteorological and biophysical drivers in the flux footprints. We use wavelet transforms of the original high-frequency data to improve spatial discretization of the flux observations. This also enables the quantification of continuous and biophysically relevant land cover properties in the flux footprint of each observation. A machine learning technique is then employed to extract and quantify the functional relationships between flux observations and the meteorological and biophysical drivers. The resulting ERFs are used to extrapolate fluxes over spatio-temporally explicit grids of the study area. The

  8. An Airborne Infrared Spectrometer for Solar Eclipse Observations

    NASA Astrophysics Data System (ADS)

    Samra, Jenna; DeLuca, Edward E.; Golub, Leon; Cheimets, Peter; Philip, Judge

    2016-05-01

    The airborne infrared spectrometer (AIR-Spec) is an innovative solar spectrometer that will observe the 2017 solar eclipse from the NSF/NCAR High-Performance Instrumented Airborne Platform for Environmental Research (HIAPER). AIR-Spec will image five infrared coronal emission lines to determine whether they may be useful probes of coronal magnetism.The solar magnetic field provides the free energy that controls coronal heating, structure, and dynamics. Energy stored in coronal magnetic fields is released in flares and coronal mass ejections and ultimately drives space weather. Therefore, direct coronal field measurements have significant potential to enhance understanding of coronal dynamics and improve solar forecasting models. Of particular interest are observations of field lines in the transitional region between closed and open flux systems, providing important information on the origin of the slow solar wind.While current instruments routinely observe only the photospheric and chromospheric magnetic fields, AIR-Spec will take a step toward the direct observation of coronal fields by measuring plasma emission in the infrared at high spatial and spectral resolution. During the total solar eclipse of 2017, AIR-Spec will observe five magnetically sensitive coronal emission lines between 1.4 and 4 µm from the HIAPER Gulfstream V at an altitude above 14.9 km. The instrument will measure emission line intensity, width, and Doppler shift, map the spatial distribution of infrared emitting plasma, and search for waves in the emission line velocities.AIR-Spec consists of an optical system (feed telescope, grating spectrometer, and infrared detector) and an image stabilization system, which uses a fast steering mirror to correct the line-of-sight for platform perturbations. To ensure that the instrument meets its research goals, both systems are undergoing extensive performance modeling and testing. These results are shown with reference to the science requirements.

  9. Validation of the CALIPSO-CALIOP extinction coefficients from in situ observations in midlatitude cirrus clouds during the CIRCLE-2 experiment

    NASA Astrophysics Data System (ADS)

    Mioche, Guillaume; Josset, Damien; Gayet, Jean-FrançOis; Pelon, Jacques; Garnier, Anne; Minikin, Andreas; Schwarzenboeck, Alfons

    2010-01-01

    This paper presents a comparison of combined Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) extinction retrievals with airborne lidar and in situ cirrus cloud measurements. Specially oriented research flights were carried out in western Europe in May 2007 during the Cirrus Cloud Experiment (CIRCLE-2) with the German Deutsches Zentrum für Luft- und Raumfahrt (DLR) and the French Service des Avions Français Instrumentés pour la Recherche en Environnement (SAFIRE) Falcon aircraft equipped for remote and in situ measurements, respectively. Four cirrus cloud situations including thin cirrus layers and outflow cirrus linked to midlatitude fronts and convective systems were chosen to perform experimental collocated observations along the satellite overpasses. The measurements were carried out with temperatures ranging between -38°C and -60°C and with extinction coefficients no larger than 2 km-1. Comparisons between CALIOP and airborne lidar (LEANDRE New Generation (LNG)) attenuated backscatter coefficients reveal much larger CALIOP values for one frontal cirrus situation which could be explained by oriented pristine ice crystals. During the four selected cases the CALIOP cirrus extinction profiles were compared with in situ extinction coefficients derived from the Polar Nephelometer. The results show a very good agreement for two situations (frontal and outflow cases) despite very different cloud conditions. The slope parameters of linear fittings of CALIOP extinction coefficients with respect to in situ measurements are 0.90 and 0.94, with correlation coefficients of 0.69 and only 0.36 for the latter case because of a small number of measurements. On the contrary, significant differences are evidenced for two other situations. In thin frontal cirrus at temperatures ranging between -58°C and -60°C, systematic larger CALIOP extinctions can be explained by horizontally

  10. Analysis of ocean in situ observations and web-based visualization

    NASA Astrophysics Data System (ADS)

    Barth, Alexander; Watelet, Sylvain; Troupin, Charles; Alvera Azcarate, Aida; Santinelli, Giorgio; Hendriksen, Gerrit; Giorgetti, Alessandra; Beckers, Jean-Marie

    2016-04-01

    The sparsity of observations poses a challenge common to various ocean science disciplines. Even for physical parameters where the spatial and temporal coverage is higher, current observational networks undersample a broad spectrum of scales. The situation is generally more severe for chemical and biological parameters because related sensors are less widely deployed. The analysis tool DIVA (Data-Interpolating Variational Analysis) is designed to generate gridded fields from in situ observations. DIVA has been applied to various physical (temperature and salinity), chemical (concentration of nitrate, nitrite and phosphate) and biological parameters (abundance of a species) in the context of different European projects (SeaDataNet, EMODnet Chemistry and EMODnet Biology). We show the technologies used to visualize the gridded fields based on the Web Map Services standard. Visualization of analyses from in situ observations provides a unique set of challenges since the accuracy of the analysed field is not spatially uniform as it strongly depends on the observations location. In addition, an adequate handling of depth and time dimensions is essential. Beside visualizing the gridded fields, access is also given to the underlying observations. It is thus also possible to view more detailed information about the variability of the observations. The in situ observation visualization service allows one to display vertical profiles and time series and it is built upon OGC standards (the Web Feature Service and Web Processing Services) and following recommendation from the INSPIRE directive.

  11. Airborne stratospheric observations of major volcanic eruptions: past and future

    NASA Astrophysics Data System (ADS)

    Newman, P. A.; Aquila, V.; Colarco, P. R.

    2015-12-01

    Major volcanic eruptions (e.g. the 1991 eruption of Mt. Pinatubo) lead to a surface cooling and disruptions of the chemistry of the stratosphere. In this presentation, we will show model simulations of Mt. Pinatubo that can be used to devise a strategy for answering specific science questions. In particular, what is the initial mass injection, how is the cloud spreading, how are the stratospheric aerosols evolving, what is the impact on stratospheric chemistry, and how will climate be affected? We will also review previous stratospheric airborne observations of volcanic clouds using NASA sub-orbital assets, and discuss our present capabilities to observe the evolution of a stratospheric volcanic plume. These capabilities include aircraft such as the NASA ER-2, WB-57f, and Global Hawk. In addition, the NASA DC-8 and P-3 can be used to perform remote sensing. Balloon assets have also been employed, and new instrumentation is now available for volcanic work.

  12. Use of In Situ and Airborne Multiangle Data to Assess MODIS- and Landsat-based Estimates of Surface Albedo

    NASA Technical Reports Server (NTRS)

    Roman, Miguel O.; Gatebe, Charles K.; Shuai, Yanmin; Wang, Zhuosen; Gao, Feng; Masek, Jeff; Schaaf, Crystal B.

    2012-01-01

    The quantification of uncertainty of global surface albedo data and products is a critical part of producing complete, physically consistent, and decadal land property data records for studying ecosystem change. A current challenge in validating satellite retrievals of surface albedo is the ability to overcome the spatial scaling errors that can contribute on the order of 20% disagreement between satellite and field-measured values. Here, we present the results from an uncertain ty analysis of MODerate Resolution Imaging Spectroradiometer (MODIS) and Landsat albedo retrievals, based on collocated comparisons with tower and airborne multi-angular measurements collected at the Atmospheric Radiation Measurement Program s (ARM) Cloud and Radiation Testbed (CART) site during the 2007 Cloud and Land Surface Interaction Campaign (CLAS33 IC 07). Using standard error propagation techniques, airborne measurements obtained by NASA s Cloud Absorption Radiometer (CAR) were used to quantify the uncertainties associated with MODIS and Landsat albedos across a broad range of mixed vegetation and structural types. Initial focus was on evaluating inter-sensor consistency through assessments of temporal stability, as well as examining the overall performance of satellite-derived albedos obtained at all diurnal solar zenith angles. In general, the accuracy of the MODIS and Landsat albedos remained under a 10% margin of error in the SW(0.3 - 5.0 m) domain. However, results reveal a high degree of variability in the RMSE (root mean square error) and bias of albedos in both the visible (0.3 - 0.7 m) and near-infrared (0.3 - 5.0 m) broadband channels; where, in some cases, retrieval uncertainties were found to be in excess of 20%. For the period of CLASIC 07, the primary factors that contributed to uncertainties in the satellite-derived albedo values include: (1) the assumption of temporal stability in the retrieval of 500 m MODIS BRDF values over extended periods of cloud

  13. In situ observation of a soap-film catenoid—a simple educational physics experiment

    NASA Astrophysics Data System (ADS)

    Ito, Masato; Sato, Taku

    2010-03-01

    The solution to the Euler-Lagrange equation is an extremal functional. To understand that the functional is stationary at local extrema (maxima or minima), we propose a physics experiment that involves using a soap film to form a catenoid. A catenoid is a surface that is formed between two coaxial circular rings and is classified mathematically as a minimal surface. Using the soap film, we create catenoids between two rings and characterize the catenoid in situ while varying the distance between the rings. The shape of the soap film is very interesting and can be explained using dynamic mechanics. By observing the catenoid, physics students can observe local extrema phenomena. We stress that in situ observation of soap-film catenoids is an appropriate physics experiment that combines theory and experimentation.

  14. European methodology for testing the airborne sound insulation characteristics of noise barriers in situ: experimental verification and comparison with laboratory data

    PubMed

    Garai; Guidorzi

    2000-09-01

    In the frame of the 1994-1997 Standard, Measurement and Testing program, the European Commission funded a research project, named Adrienne, to define new test methods for measuring the intrinsic characteristics of road traffic noise reducing devices in situ. The research team produced innovative methods for testing the sound reflection/absorption and the airborne sound insulation characteristics of noise barriers. These methods are now under consideration at CEN (European Committee for Standardization), to become European standards. The present work reports a detailed verification of the test method for airborne sound insulation over a selection of 17 noise barriers, representative of the Italian and European production. The samples were tested both outdoors, using the new Adrienne method, and in laboratory, following the European standard EN 1793-2. In both cases the single number rating for airborne sound insulation recommended by the European standard was calculated. The new method proved to be easy to use and reliable for all kinds of barriers. It has been found sensitive to quality of mounting, presence of seals, and other details typical of outdoor installations. The comparison between field and laboratory results shows a good correlation, while existing differences can be explained with the different sound fields and mounting conditions between the outdoor and laboratory tests. It is concluded that the Adrienne method is adequate for its intended use. PMID:11008808

  15. Airborne in situ vertical profiling of HDO / H216O in the subtropical troposphere during the MUSICA remote sensing validation campaign

    NASA Astrophysics Data System (ADS)

    Dyroff, C.; Sanati, S.; Christner, E.; Zahn, A.; Balzer, M.; Bouquet, H.; McManus, J. B.; Gonzalez-Ramos, Y.; Schneider, M.

    2015-05-01

    Vertical profiles of water vapor (H2O) and its isotope ratio D / H expressed as δD(H2O) were measured in situ by the ISOWAT II diode-laser spectrometer during the MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water (MUSICA) airborne campaign. We present recent modifications of the instrument design. The instrument calibration on the ground as well as in flight is described. Based on the calibration measurements, the humidity-dependent uncertainty of our airborne data is determined. For the majority of the airborne data we achieved an accuracy (uncertainty of the mean) of Δ(δD) ≈10‰. Vertical profiles between 150 and ~7000 m were obtained during 7 days in July and August 2013 over the subtropical North Atlantic Ocean near Tenerife. The flights were coordinated with ground-based (Network for the Detection of Atmospheric Composition Change, NDACC) and space-based (Infrared Atmospheric Sounding Interferometer, IASI) FTIR remote sensing measurements of δD(H2O) as a means to validate the remote sensing humidity and δD(H2O) data products. The results of the validation are presented in detail in a separate paper (Schneider et al., 2014). The profiles were obtained with a high vertical resolution of around 3 m. By analyzing humidity and δD(H2O) correlations we were able to identify different layers of air masses with specific isotopic signatures. The results are discussed.

  16. Airborne in situ vertical profiling of HDO/H216O in the subtropical troposphere during the MUSICA remote sensing validation campaign

    NASA Astrophysics Data System (ADS)

    Dyroff, C.; Sanati, S.; Christner, E.; Zahn, A.; Balzer, M.; Bouquet, H.; McManus, J. B.; González-Ramos, Y.; Schneider, M.

    2015-01-01

    Vertical profiles of water vapor (H2O) and its isotope ratio D / H expressed as δ D(H2O were measured in situ by the ISOWAT II diode-laser spectrometer during the MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water (MUSICA) airborne campaign. We present recent modifications of the instrument design. The instrument calibration on the ground as well as in flight is described. Based on the calibration measurements, the humidity-dependent uncertainty of our airborne data is determined. For the majority of the airborne data we achieved an accuracy (uncertainty of the mean) of Δ(δ D) ≈ 10‰. Vertical profiles between 150 and ~7000 m were obtained during 7 days in July and August 2013 over the subtropical North Atlantic Ocean near Tenerife. The flights were coordinated with ground-based (Network for the Detection of Atmospheric Composition Change, NDACC) and space-based (Infrared Atmospheric Sounding Interferometer, IASI) FTIR remote-sensing measurements of δ D(H2O) as a means to validate the remote sensing humidity and δ D(H2O) data products. The results of the validation are presented in detail in a separate paper (Schneider et al., 2014). The profiles were obtained with a high vertical resolution of around 3 m. By analyzing humidity and δ D(H2O) correlations we were able to identify different layers of airmasses with specific isotopic signatures. The results are discussed.

  17. Overview Of Haze And Smoke Measurements in Northern High Latitudes And California During ARCTAS Using The NASA Ames Airborne Sunphotometer And Associated In Situ And Remote Sensors

    NASA Astrophysics Data System (ADS)

    Russell, P. B.; Redemann, J.; Livingston, J.; Shinozuka, Y.; Ramachandran, S.; Johnson, R. R.; Clarke, A. D.; Howell, S. G.; McNaughton, C.; Holben, B.; O'Neill, N.; McArthur, B.; Reid, E.; Ferrare, R. A.; Hostetler, C. A.

    2009-12-01

    The 14-channel NASA Ames Airborne Tracking Sunphotometer (AATS-14) operated in a suite of remote and in-situ sensors aboard the NASA P-3 aircraft during the 2008 Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) field campaign. Included were 8 Spring flights in the Arctic and 13 Summer flights (3 in California and 10 in Canada), each coordinated with one or more satellite overpasses, other aircraft (e.g., NASA B-200 and DC-8, NOAA P-3), and/or ground-based Aerosol Robotic Network (AERONET) measurements. This presentation gives an overview of AATS-14 aerosol optical depth (AOD) spectra and related parameters such as Angstrom exponent and fine mode fraction. We quantify the mutual consistency of AODs calculated from measurements by AATS-14, by the HiGEAR (University of Hawaii Group for Environmental Aerosol Research) suite of P-3 in-situ optical instruments, and by AERONET . The vertical integral of the HiGEAR in-situ scattering and absorption coefficients recorded during spiral profiles typically falls within 10% ± 0.02 of the AATS-14 AOD values interpolated to 450, 550 and 700 nm. Corresponding Angstrom exponents typically differ by ~0.1. AATS-14 AODs adjusted for the contribution of the layer below the aircraft (estimated with HiGEAR data) generally agree with the full column AERONET values to within the combined uncertainties. Example results from multi-platform comparisons are also shown. These results provide context for the more detailed AATS-14 results in other presentations, e.g., by Redemann et al. (focusing on the multi-platform, multi-sensor smoke case of 30 Jun 2008), Livingston et al. (comparisons to MODIS, MISR, OMI, POLDER, CALIPSO, and airborne lidar), and Shinozuka et al. (relationship to cloud condensation nuclei and other measurements).

  18. Comparison of cloud properties observed from in situ and satellite measurements

    NASA Astrophysics Data System (ADS)

    Noble, S. R.; Hudson, J. G.

    2013-12-01

    Climate is influenced by clouds reflecting radiation. Adjustments in cloud properties occur with changes to the cloud environment such as changes in aerosol or vertical velocity. These adjustments change the cloud radiative forcing. Three ways exist to study cloud properties: in situ observations, satellite observations, and modeling of cloud properties. Data sets from in situ measurements in field campaigns such as Physics of Stratocumulus Top (POST) (Hudson et al. 2010; Hudson and Noble 2013) provide good resolution of local cloud properties but are not extensive over time or globally. Satellites provide data coverage on a global scale and over long times but at infrequent periods locally. Uncertainties arise between these two methods when attempting to understand cloud properties and effects on radiative forcing. To understand these uncertainties, we compared MODIS data to vertical cloud pass data from the POST field campaign. Data from 9 in situ slant passes were compared to data from 9 satellite passes on 8 days. Figure 1 shows these comparisons of effective radius (re) (black) and cloud optical depth (COD) (red). COD from the satellite passes compares well with in situ data near the 1:1 line. The correlation coefficient (R) for COD is 0.95 with a slope (k) of 1.05. However, re is not near the 1:1 line and shows a steep k of 2.36, which suggests an over-prediction by the satellite observations, while R is only 0.57. Satellite re compared better to maximum in situ re which yielded a flatter k of 1.44 but an R of 0.59. Maximum re occurred a few meters below stratus cloud top that may suggest larger droplets dominate over cloud thickness in satellite observations. The satellite also over-predicts liquid water path (LWP, not shown) with a k of 1.42 and an R of 0.90. Because satellite re is over-predicting, calculations of environmental precursors become more difficult. However, COD is more related to albedo and observations compare well, which appears to validate

  19. Airborne lidar observations of clouds in the Antarctic troposphere

    NASA Astrophysics Data System (ADS)

    Morley, Bruce M.; Uthe, Edward E.; Viezee, William

    1989-06-01

    In January 1986, SRI International made exploratory airborne observations of Antarctic tropospheric clouds with a downward-viewing lidar onboard an LC-130 supply aircraft. Frequency of observations depended upon the schedule of supply missions. Two types of clouds were observed: relatively opaque, midlevel cloud layers 3.0 to 4.0 km below flight level (about 4.0 to 4.5 km MSL); and higher altitude optically transparent cirrus clouds exhibiting long trails or curtains of ice crystals that extended from flight level downward to the top of the midlevel clouds and, frequently, to ground level. The midlevel clouds were often multilayered and, at times, showed wave or cellular structure associated with cloud streets. The ice crystal trails from the cirrus clouds showed evidence of the presence of strong vertical wind shear, and were observed to “seed” the midlevel cloud layers, producing large breaks in the overcast. These exploratory observations attest to the utility of lidar for atmospheric research studies in the Antarctic region.

  20. Ice surface temperatures: seasonal cycle and daily variability from in-situ and satellite observations

    NASA Astrophysics Data System (ADS)

    Madsen, Kristine S.; Dybkjær, Gorm; Høyer, Jacob L.; Nielsen-Englyst, Pia; Rasmussen, Till A. S.; Tonboe, Rasmus T.

    2016-04-01

    Surface temperature is an important parameter for understanding the climate system, including the Polar Regions. Yet, in-situ temperature measurements over ice- and snow covered regions are sparse and unevenly distributed, and atmospheric circulation models estimating surface temperature may have large biases. To change this picture, we will analyse the seasonal cycle and daily variability of in-situ and satellite observations, and give an example of how to utilize the data in a sea ice model. We have compiled a data set of in-situ surface and 2 m air temperature observations over land ice, snow, sea ice, and from the marginal ice zone. 2523 time series of varying length from 14 data providers, with a total of more than 13 million observations, have been quality controlled and gathered in a uniform format. An overview of this data set will be presented. In addition, IST satellite observations have been processed from the Metop/AVHRR sensor and a merged analysis product has been constructed based upon the Metop/AVHRR, IASI and Modis IST observations. The satellite and in-situ observations of IST are analysed in parallel, to characterize the IST variability on diurnal and seasonal scales and its spatial patterns. The in-situ data are used to estimate sampling effects within the satellite observations and the good coverage of the satellite observations are used to complete the geographical variability. As an example of the application of satellite IST data, results will be shown from a coupled HYCOM-CICE ocean and sea ice model run, where the IST products have been ingested. The impact of using IST in models will be assessed. This work is a part of the EUSTACE project under Horizon 2020, where the ice surface temperatures form an important piece of the puzzle of creating an observationally based record of surface temperatures for all corners of the Earth, and of the ESA GlobTemperature project which aims at applying surface temperatures in models in order to

  1. Challenges in the Management and Stewardship of Airborne Observational Data at the National Center for Atmospheric Research (NCAR) Earth Observing Laboratory (EOL)

    NASA Astrophysics Data System (ADS)

    Aquino, J.; Daniels, M. D.

    2015-12-01

    The National Science Foundation (NSF) provides the National Center for Atmospheric Research (NCAR) Earth Observing Laboratory (EOL) funding for the operation, maintenance and upgrade of two research aircraft: the NSF/NCAR High-performance Instrumented Airborne Platform for Environmental Research (HIAPER) Gulfstream V and the NSF/NCAR Hercules C-130. A suite of in-situ and remote sensing airborne instruments housed at the EOL Research Aviation Facility (RAF) provide a basic set of measurements that are typically deployed on most airborne field campaigns. In addition, instruments to address more specific research requirements are provided by collaborating participants from universities, industry, NASA, NOAA or other agencies (referred to as Principal Investigator, or PI, instruments). At the 2014 AGU Fall Meeting, a poster (IN13B-3639) was presented outlining the components of Airborne Data Management included field phase data collection, formats, data archival and documentation, version control, storage practices, stewardship and obsolete data formats, and public data access. This talk will cover lessons learned, challenges associated with the above components, and current developments to address these challenges, including: tracking data workflows for aircraft instrumentation to facilitate identification, and correction, of gaps in these workflows; implementation of dataset versioning guidelines; and assignment of Digital Object Identifiers (DOIs) to data and instrumentation to facilitate tracking data and facility use in publications.

  2. High resolution transmission electron microscopic in-situ observations of plastic deformation of compressed nanocrystalline gold

    SciTech Connect

    Wang, Guoyong; Lian, Jianshe; Jiang, Qing; Sun, Sheng; Zhang, Tong-Yi

    2014-09-14

    Nanocrystalline (nc) metals possess extremely high strength, while their capability to deform plastically has been debated for decades. Low ductility has hitherto been considered an intrinsic behavior for most nc metals, due to the lack of five independent slip systems actively operating during deformation in each nanograin. Here we report in situ high resolution transmission electron microscopic (HRTEM) observations of deformation process of nc gold under compression, showing the excellent ductility of individual and aggregate nanograins. Compression causes permanent change in the profile of individual nanograins, which is mediated by dislocation slip and grain rotation. The high rate of grain boundary sliding and large extent of widely exited grain rotation may meet the boundary compatibility requirements during plastic deformation. The in situ HRTEM observations suggest that nc gold is not intrinsically brittle under compressive loading.

  3. Direct in situ observations of single Fe atom catalytic processes and anomalous diffusion at graphene edges.

    PubMed

    Zhao, Jiong; Deng, Qingming; Avdoshenko, Stanislav M; Fu, Lei; Eckert, Jürgen; Rümmeli, Mark H

    2014-11-01

    Single-atom catalysts are of great interest because of their high efficiency. In the case of chemically deposited sp(2) carbon, the implementation of a single transition metal atom for growth can provide crucial insight into the formation mechanisms of graphene and carbon nanotubes. This knowledge is particularly important if we are to overcome fabrication difficulties in these materials and fully take advantage of their distinct band structures and physical properties. In this work, we present atomically resolved transmission EM in situ investigations of single Fe atoms at graphene edges. Our in situ observations show individual iron atoms diffusing along an edge either removing or adding carbon atoms (viz., catalytic action). The experimental observations of the catalytic behavior of a single Fe atom are in excellent agreement with supporting theoretical studies. In addition, the kinetics of Fe atoms at graphene edges are shown to exhibit anomalous diffusion, which again, is in agreement with our theoretical investigations.

  4. In situ observation of optomechanical Bloch oscillations in an optical cavity

    NASA Astrophysics Data System (ADS)

    Keßler, H.; Klinder, J.; Prasanna Venkatesh, B.; Georges, Ch; Hemmerich, A.

    2016-10-01

    It is shown experimentally that a Bose–Einstein condensate inside an optical cavity, operating in the regime of strong cooperative coupling, responds to an external force by an optomechanical Bloch oscillation, which can be directly observed in the light leaking out of the cavity. Previous theoretical work predicts that the frequency of this oscillation matches with that of conventional Bloch oscillations such that its in situ monitoring may help to increase the data acquisition speed in precision force measurements.

  5. Airborne In-Situ Measurements of Formaldehyde over California: First Results from the Compact Formaldehyde Fluorescence Experiment (COFFEE) Instrument

    NASA Technical Reports Server (NTRS)

    Marrero, Josette; St. Clair, Jason; Yates, Emma L.; Gore, Warren; Swanson, Andrew K.; Iraci, Laura T.; Hanisco, Thomas F.

    2016-01-01

    Formaldehyde (HCHO) is one of the most abundant oxygenated volatile organic compounds (VOCs) in the atmosphere, playing a role multiple atmospheric processes. Measurements of HCHO can be used to help quantify convective transport, the abundance of VOCs, and ozone production in urban environments. The Compact Formaldehyde FluorescencE Experiment (COFFEE) instrument uses Non-Resonant Laser Induced Fluorescence (NR-LIF) to detect trace concentrations of HCHO as part of the Alpha Jet Atmospheric eXperiment (AJAX) payload. Developed at NASA GSFC, COFFEE is a small, low maintenance instrument with a sensitivity of 100 pptv and a quick response time (1 sec). The COFFEE instrument has been customized to fit in an external wing pod on the Alpha Jet aircraft based at NASA ARC. The instrument can operate over a broad range of altitudes, from boundary layer to lower stratosphere, making it well suited for the Alpha Jet, which can access altitudes from the surface up to 40,000 ft. Results of the first COFFEE science flights preformed over the California's Central Valley will be presented. Boundary layer measurements and vertical profiles in the tropospheric column will both be included. This region is of particular interest, due to its elevated levels of HCHO, revealed in satellite images, as well as its high ozone concentrations. In addition to HCHO, the AJAX payload includes measurements of atmospheric ozone, methane, and carbon dioxide. Formaldehyde is one of the few urban pollutants that can be measured from space. Plans to compare in-situ COFFEE data with satellite-based HCHO observations such as those from OMI (Aura) and OMPS (SuomiNPP) will also be presented.

  6. Airborne In-Situ Measurements of Formaldehyde Over California: First Results from the Compact Formaldehyde Fluorescence Experiment (COFFEE) Instrument

    NASA Technical Reports Server (NTRS)

    Marrero, Josette Elizabeth; Saint Clair, Jason; Yates, Emma L.; Gore, Warren; Swanson, Andrew K.; Iraci, Laura T.; Hanisco, Thomas F.

    2016-01-01

    Formaldehyde (HCHO) is one of the most abundant oxygenated volatile organic compounds (VOCs) in the atmosphere, playing a role multiple atmospheric processes. Measurements of HCHO can be used to help quantify convective transport, the abundance of VOCs, and ozone production in urban environments. The Compact Formaldehyde FluorescencE Experiment (COFFEE) instrument uses Non-Resonant Laser Induced Fluorescence (NR-LIF) to detect trace concentrations of HCHO as part of the Alpha Jet Atmospheric eXperiment (AJAX) payload. Developed at NASA GSFC, COFFEE is a small, low maintenance instrument with a sensitivity of 100 pptv and a quick response time (1 sec). The COFFEE instrument has been customized to fit in an external wing pod on the Alpha Jet aircraft based at NASA ARC. The instrument can operate over a broad range of altitudes, from boundary layer to lower stratosphere, making it well suited for the Alpha Jet, which can access altitudes from the surface up to 40,000 ft. Results of the first COFFEE science flights preformed over the California's Central Valley will be presented. Boundary layer measurements and vertical profiles in the tropospheric column will both be included. This region is of particular interest, due to its elevated levels of HCHO, revealed in satellite images, as well as its high ozone concentrations. In addition to HCHO, the AJAX payload includes measurements of atmospheric ozone, methane, and carbon dioxide. Formaldehyde is one of the few urban pollutants that can be measured from space. Plans to compare in-situ COFFEE data with satellite-based HCHO observations such as those from OMI (Aura) and OMPS (SuomiNPP) will also be presented.

  7. Fast-response airborne in situ measurements of HNO3 during the Texas 2000 Air Quality Study

    NASA Astrophysics Data System (ADS)

    Neuman, J. A.; Huey, L. G.; Dissly, R. W.; Fehsenfeld, F. C.; Flocke, F.; Holecek, J. C.; Holloway, J. S.; Hübler, G.; Jakoubek, R.; Nicks, D. K.; Parrish, D. D.; Ryerson, T. B.; Sueper, D. T.; Weinheimer, A. J.

    2002-10-01

    Nitric acid (HNO3) was measured from an aircraft in the planetary boundary layer and free troposphere up to 7 km on 14 flights during the Texas Air Quality Study in August and September 2000. HNO3 mixing ratios were measured at 1 Hz using a fast-response chemical ionization mass spectrometer with SiF5- reagent ions. HNO3 measurement using this highly selective ion chemistry is insensitive to water vapor and is not degraded by interferences from other species. Rapid time response (1 s) was achieved using a heated Teflon inlet. In-flight standard addition calibrations from a HNO3 permeation source were used to determine the instrument sensitivity of 1.1 ± 0.1 ion counts pptv-1 s-1 over the duration of the study. Contributions to the HNO3 signal from instrument artifacts were accounted for by regularly performing in-flight instrument background checks, where HNO3 was removed from the ambient air sample by diverting the sampled air though a nylon wool scrubber. Measurement inaccuracy, which is determined from uncertainties in the standard addition calibrations, was ±10%. Measurement precision at low HNO3 levels was ±25 pptv (1σ) for the 1 Hz data and ±9 pptv for 10 s averages of the 1 s measurements. Coincident in situ measurements of other reactive nitrogen species are used to examine NOy partitioning and HNO3 formation during this month long measurement campaign. The sum of the individually measured reactive nitrogen species is shown to be in agreement with the measured NOy. HNO3 formation in plumes from electric utility power plants, urban areas, and petrochemical facilities was studied. The observed differences in the fractional contribution of HNO3 to NOy in plumes from different anthropogenic source types are discussed.

  8. Deriving an atmospheric budget of total organic bromine using airborne in-situ measurements from the Western Pacific during SHIVA

    NASA Astrophysics Data System (ADS)

    Sala, S.; Bönisch, H.; Keber, T.; Oram, D. E.; Mills, G.; Engel, A.

    2014-02-01

    During the SHIVA (Stratospheric Ozone: Halogen Impacts in a Varying Atmosphere) project an extensive dataset of all halogen species relevant for the atmospheric budget of total organic bromine has been collected in the West Pacific region using the FALCON aircraft operated by the German Aerospace agency DLR (Deutsches Zentrum für Luft- und Raumfahrt) covering a vertical range from the planetary boundary layer up to the ceiling altitude of the aircraft of 13 km. In total, more than 700 measurements were performed with the newly developed fully-automated in-situ instrument GHOST-MS (Gas cHromatograph for the Observation of Tracers - coupled with a Mass Spectrometer) by the Goethe University of Frankfurt (GUF) and with the onboard whole-air sampler WASP with subsequent ground based state-of-the-art GC/MS analysis by the University of East Anglia (UEA). Both instruments yield good agreement for all major (CHBr3 and CH2Br2) and minor (CHBrCl, CHBrCl2 and CHBr2Cl) VSLS (very short-lived substances), at least at the level of their 2 σ measurement uncertainties. In contrast to the suggestion that the Western Pacific could be a major source region for VSLS (Pyle et al., 2011), we found only slightly enhanced mixing ratios of brominated halogen source gases relative to the levels reported in Montzka et al. (2011) for other tropical regions. A budget for total organic bromine, including all four halons,CH3Br and the VSLS, is derived for the upper troposphere, the input region for the TTL and thus also for the stratosphere, compiled from the SHIVA dataset. With exception of the two minor VSLS CHBrCl2 and CHBr2Cl, excellent agreement with the values reported in Montzka et al. (2011) is found, while being slightly higher than previous studies from our group based on balloon-borne measurements.

  9. Remote and In Situ Observations of Surfzone and Inner-Shelf Tracer Dispersion

    NASA Astrophysics Data System (ADS)

    Hally-Rosendahl, K.; Feddersen, F.; Clark, D.; Guza, R. T.

    2014-12-01

    Surfzone and inner-shelf tracer dispersion was observed at the approximately alongshore-uniform Imperial Beach, California during the IB09 experiment. Rhodamine dye tracer, released continuously near the shoreline for several hours, was advected alongshore by breaking wave- and wind-driven currents, and ejected offshore from the surfzone to the inner-shelf by transient rips. Aerial multispectral imaging of inner-shelf dye concentration complemented in situ surfzone and inner-shelf measurements of dye, temperature, waves, and currents, providing tracer transport and dispersion observations spanning approximately 400 m cross-shore and 3 km alongshore. Combined in situ and aerial measurements approximately close a surfzone and inner-shelf dye budget. Mean alongshore dye dilution follows a power-law relationship, and both spatial and temporal dye variability decrease with distance from the release. Aerial images reveal coherent inner-shelf dye plume structures extending over 300 m offshore with alongshore length scales up to 400 m. Plume tracking among successive images yields inner-shelf alongshore advection rates consistent with in situ observations. Alongshore advection is faster within the surfzone than on the inner-shelf, and the leading alongshore edge of inner-shelf dye is due to local transient rip ejections from the surfzone. A combination of in situ and aerial surfzone and inner-shelf measurements are used to quantify cross- and alongshore dye tracer transports. This work is funded by NSF (including a Graduate Research Fellowship, Grant No. DGE1144086), ONR, and California Sea Grant. Figure: Aerial multispectral image of surface dye concentration (parts per billion, see colorbar) versus cross-shore coordinate x and alongshore coordinate y, approximately 5 hours after the start of a continuous dye release (green star). The mean shoreline is at x=0 m. Dark gray indicates the beach and a pier, and light gray indicates regions outside the imaged area. Black

  10. Airborne Observations of Ammonia Emissions from North Carolina Swine Facilities

    NASA Astrophysics Data System (ADS)

    Nowak, J. B.; Neuman, J. A.; Liao, J.; Welti, A.; Middlebrook, A. M.; McKeen, S. A.; Trainer, M.; Parrish, D. D.

    2013-12-01

    Ammonia (NH3) is the dominant gas-phase base in the troposphere. As a consequence, NH3 abundance influences particle formation and composition. Anthropogenic emissions of NH3 can react with sulfuric acid (H2SO4) and nitric acid (HNO3), photochemical oxidation products of sulfur dioxide (SO2) and nitrogen oxides (NOx (NO + NO2)), to form ammoniated particles that typically account for half or more of measured PM2.5 mass in the Eastern US. NH3 emissions are predominantly from agricultural sources, primarily livestock animal waste and crop fertilization. Accurate NH3 emissions estimates from these sources are necessary for developing effective particle control strategies. Swine facilities in North Carolina are one of the largest source of NH3 emissions in the Southeastern US. Airborne measurements of NH3 and particulate ammonium (NH4+) made aboard the NOAA WP-3D aircraft as part of the recent 2013 SENEX field campaign are used to quantify NH3 emissions from North Carolina swine facilities. The observed NH3 emissions are compared to swine facility emissions estimates from current emissions inventories. In addition, the NH3 emissions from swine facilities are placed in the broader context of NH3 sources through comparison to recent emissions observations from dairy facilities in California. The July 10 SENEX WP-3D flight track colored and sized by observed NH3 mixing ratios.

  11. Recrystallization phenomena in an IF steel observed by in situ EBSD experiments.

    PubMed

    Nakamichi, H; Humphreys, F J; Brough, I

    2008-06-01

    In situ electron backscatter diffraction microstructural analysis of recrystallizing interstitial free steels deformed to strains of 0.75 and 1.6 has been carried out in a FEG-SEM. The experimental procedures are discussed, and it is shown that there is no degradation of the electron backscatter diffraction patterns at temperatures up to 800 degrees C. Analysis of the surface and interior microstructures of annealed samples shows only minor difference, which suggests that in situ annealing experiments are of value. In addition, it is shown that in situ measurements allow a detailed comparison between the same areas before and after annealing, thereby providing information about the recrystallization mechanisms. Sequential recrystallization phenomena, such as initiation and growth of new grains, are observed at temperatures over 740 degrees C, and depending on the deformation histories, different recrystallization behaviour is observed. It is found that {111} <123> recrystallized grains are preferentially formed in the highly deformed material, whereas no strong recrystallization texture is formed in the lower strained material. PMID:18503673

  12. Calculated in situ rock density from gravity observations, UA-1 (Cannikin) emplacement hole, Amchitka Island, Alaska

    USGS Publications Warehouse

    Healey, D.L.

    1971-01-01

    Gravity observations were made on the ground surface and at a depth of 5,854 feet in drill hole UA-1. Two attempts to measure the free-air gradient utilizing the headframe over the drill hole were unsuccessful owing to mechanical vibrations in the structure. Because of the uncertainty in the measured free-air gradients these values were discarded and the average value (0.09406 mgal/ft) was used in the calculations. The calculated in situ bulk density is 2.36 g/cc. The weighted average bulk density determined from 47 core samples taken in the adjacent UAE-1 drill hole is also 2.36 g/cc. An analysis of selected portions of density logs provides an in situ bulk density of 2.37 g/cc.

  13. In-Situ atomic force microscopic observation of ion beam bombarded plant cell envelopes

    NASA Astrophysics Data System (ADS)

    Sangyuenyongpipat, S.; Yu, L. D.; Brown, I. G.; Seprom, C.; Vilaithong, T.

    2007-04-01

    A program in ion beam bioengineering has been established at Chiang Mai University (CMU), Thailand, and ion beam induced transfer of plasmid DNA molecules into bacterial cells (Escherichia coli) has been demonstrated. However, a good understanding of the fundamental physical processes involved is lacking. In parallel work, onion skin cells have been bombarded with Ar+ ions at energy 25 keV and fluence1-2 × 1015 ions/cm2, revealing the formation of microcrater-like structures on the cell wall that could serve as channels for the transfer of large macromolecules into the cell interior. An in-situ atomic force microscope (AFM) system has been designed and installed in the CMU bio-implantation facility as a tool for the observation of these microcraters during ion beam bombardment. Here we describe some of the features of the in-situ AFM and outline some of the related work.

  14. Highly Dense Isolated Metal Atom Catalytic Sites: Dynamic Formation and In Situ Observations.

    PubMed

    Chen, Yaxin; Kasama, Takeshi; Huang, Zhiwei; Hu, Pingping; Chen, Jianmin; Liu, Xi; Tang, Xingfu

    2015-11-23

    Atomically dispersed noble-metal catalysts with highly dense active sites are promising materials with which to maximise metal efficiency and to enhance catalytic performance; however, their fabrication remains challenging because metal atoms are prone to sintering, especially at a high metal loading. A dynamic process of formation of isolated metal atom catalytic sites on the surface of the support, which was achieved starting from silver nanoparticles by using a thermal surface-mediated diffusion method, was observed directly by using in situ electron microscopy and in situ synchrotron X-ray diffraction. A combination of electron microscopy images with X-ray absorption spectra demonstrated that the silver atoms were anchored on five-fold oxygen-terminated cavities on the surface of the support to form highly dense isolated metal active sites, leading to excellent reactivity in catalytic oxidation at low temperature. This work provides a general strategy for designing atomically dispersed noble-metal catalysts with highly dense active sites.

  15. Deriving an atmospheric budget of total organic bromine using airborne in situ measurements from the western Pacific area during SHIVA

    NASA Astrophysics Data System (ADS)

    Sala, S.; Bönisch, H.; Keber, T.; Oram, D. E.; Mills, G.; Engel, A.

    2014-07-01

    During the recent SHIVA (Stratospheric Ozone: Halogen Impacts in a Varying Atmosphere) project an extensive data set of all halogen species relevant for the atmospheric budget of total organic bromine was collected in the western Pacific region using the Falcon aircraft operated by the German Aerospace agency DLR (Deutsches Zentrum für Luft- und Raumfahrt) covering a vertical range from the planetary boundary layer up to the ceiling altitude of the aircraft of 13 km. In total, more than 700 measurements were performed with the newly developed fully automated in situ instrument GHOST-MS (Gas chromatograph for the Observation of Tracers - coupled with a Mass Spectrometer) by the Goethe University of Frankfurt (GUF) and with the onboard whole-air sampler WASP with subsequent ground-based state-of-the-art GC / MS analysis by the University of East Anglia (UEA). Both instruments yield good agreement for all major (CHBr3 and CH2Br2) and minor (CH2BrCl, CHBrCl2 and CHBr2Cl) VSLS (very short-lived substances), at least at the level of their 2σ measurement uncertainties. In contrast to the suggestion that the western Pacific could be a region of strongly increased atmospheric VSLS abundance (Pyle et al., 2011), we found only in the upper troposphere a slightly enhanced amount of total organic bromine from VSLS relative to the levels reported in Montzka and Reimann et al. (2011) for other tropical regions. From the SHIVA observations in the upper troposphere, a budget for total organic bromine, including four halons (H-1301, H-1211, H-1202, H-2402), CH3Br and the VSLS, is derived for the level of zero radiative heating (LZRH), the input region for the tropical tropopause layer (TTL) and thus also for the stratosphere. With the exception of the two minor VSLS CHBrCl2 and CHBr2Cl, excellent agreement with the values reported in Montzka and Reimann et al. (2011) is found, while being slightly higher than previous studies from our group based on balloon-borne measurements.

  16. In Situ Observations of Phase Transitions in Metastable Nickel (Carbide)/Carbon Nanocomposites

    PubMed Central

    2016-01-01

    Nanocomposite thin films comprised of metastable metal carbides in a carbon matrix have a wide variety of applications ranging from hard coatings to magnetics and energy storage and conversion. While their deposition using nonequilibrium techniques is established, the understanding of the dynamic evolution of such metastable nanocomposites under thermal equilibrium conditions at elevated temperatures during processing and during device operation remains limited. Here, we investigate sputter-deposited nanocomposites of metastable nickel carbide (Ni3C) nanocrystals in an amorphous carbon (a-C) matrix during thermal postdeposition processing via complementary in situ X-ray diffractometry, in situ Raman spectroscopy, and in situ X-ray photoelectron spectroscopy. At low annealing temperatures (300 °C) we observe isothermal Ni3C decomposition into face-centered-cubic Ni and amorphous carbon, however, without changes to the initial finely structured nanocomposite morphology. Only for higher temperatures (400–800 °C) Ni-catalyzed isothermal graphitization of the amorphous carbon matrix sets in, which we link to bulk-diffusion-mediated phase separation of the nanocomposite into coarser Ni and graphite grains. Upon natural cooling, only minimal precipitation of additional carbon from the Ni is observed, showing that even for highly carbon saturated systems precipitation upon cooling can be kinetically quenched. Our findings demonstrate that phase transformations of the filler and morphology modifications of the nanocomposite can be decoupled, which is advantageous from a manufacturing perspective. Our in situ study also identifies the high carbon content of the Ni filler crystallites at all stages of processing as the key hallmark feature of such metal–carbon nanocomposites that governs their entire thermal evolution. In a wider context, we also discuss our findings with regard to the much debated potential role of metastable Ni3C as a catalyst phase in graphene and

  17. Long-term groundwater storage change in Victoria, Australia from satellite gravity and in situ observations

    NASA Astrophysics Data System (ADS)

    Chen, J. L.; Wilson, C. R.; Tapley, B. D.; Scanlon, Bridget; Güntner, Andreas

    2016-04-01

    Analysis based on satellite gravity measurements from the Gravity Recovery and Climate Experiment (GRACE) and land surface models indicates that groundwater storage in Victoria, Australia had been declining steadily, until a trend reversal around early 2010, attributed to two wetter seasons in 2010 and 2011. In situ groundwater level measurements (from a network of 1395 bores in Victoria) also indicate a steady groundwater depletion since the early 1990's, and show remarkable agreement with GRACE estimates for the 10-year period (2003-2012) in common with the GRACE mission. Groundwater depletion rates for 2005 to 2009 are relatively large as indicated by both GRACE estimates (8.0 ± 1.7 km3/yr) and in situ measurements (8.3 ± 3.4 km3/yr). Over the same period (2005-2009), GRACE measurements capture significant groundwater depletion in a wider region covering much of the southern Murray-Darling Basin, and the total groundwater depletion rate in this region is about 17.2 ± 4.7 km3/yr. Annual groundwater storage changes are strongly correlated with precipitation anomalies, but only about one-fifth of anomalous precipitation contributes to groundwater recharge. The strong correlation suggests that this groundwater depletion is primarily related to drought with related groundwater pumping for agricultural and domestic consumption. The remarkable agreement between GRACE estimates and in situ measurements demonstrates the great potential of satellite gravity observations in combination with land surface model estimates to quantify changes in regional groundwater resources, especially when in situ measurements are limited or unavailable. This study shows the importance of reducing leakage bias in GRACE observations and the effectiveness of the forward modeling iterative method used.

  18. SOFIA's Choice: Automating the Scheduling of Airborne Observations

    NASA Technical Reports Server (NTRS)

    Frank, Jeremy; Norvig, Peter (Technical Monitor)

    1999-01-01

    This paper describes the problem of scheduling observations for an airborne telescope. Given a set of prioritized observations to choose from, and a wide range of complex constraints governing legitimate choices and orderings, how can we efficiently and effectively create a valid flight plan which supports high priority observations? This problem is quite different from scheduling problems which are routinely solved automatically in industry. For instance, the problem requires making choices which lead to other choices later, and contains many interacting complex constraints over both discrete and continuous variables. Furthermore, new types of constraints may be added as the fundamental problem changes. As a result of these features, this problem cannot be solved by traditional scheduling techniques. The problem resembles other problems in NASA and industry, from observation scheduling for rovers and other science instruments to vehicle routing. The remainder of the paper is organized as follows. In 2 we describe the observatory in order to provide some background. In 3 we describe the problem of scheduling a single flight. In 4 we compare flight planning and other scheduling problems and argue that traditional techniques are not sufficient to solve this problem. We also mention similar complex scheduling problems which may benefit from efforts to solve this problem. In 5 we describe an approach for solving this problem based on research into a similar problem, that of scheduling observations for a space-borne probe. In 6 we discuss extensions of the flight planning problem as well as other problems which are similar to flight planning. In 7 we conclude and discuss future work.

  19. In-situ observation of one silicon particle during the first charging

    NASA Astrophysics Data System (ADS)

    Nishikawa, Kei; Munakata, Hirokazu; Kanamura, Kiyoshi

    2013-12-01

    The understanding of volume change mechanism of silicon electrode is necessary to design a new negative electrode using silicon-based active materials. Here, the drastic volume expansion of one silicon secondary particle with μm-size was in-situ observed in order to find apparent volume expansion ratio during the first charging by using single particle measurement technique. The apparent volume expansion accompanied with the first lithiation is much larger than theoretical expectation due to the agglutination state and anisotropic property. The importance of direct observation with the single particle measurement has been affirmed for understanding the characteristics of silicon electrodes.

  20. In-situ observations of catalytic surface reactions with soft x-rays under working conditions

    NASA Astrophysics Data System (ADS)

    Toyoshima, Ryo; Kondoh, Hiroshi

    2015-03-01

    Catalytic chemical reactions proceeding on solid surfaces are an important topic in fundamental science and industrial technologies such as energy conversion, pollution control and chemical synthesis. Complete understanding of the heterogeneous catalysis and improving its efficiency to an ultimate level are the eventual goals for many surface scientists. Soft x-ray is one of the prime probes to observe electronic and structural information of the target materials. Most studies in surface science using soft x-rays have been performed under ultra-high vacuum conditions due to the technical limitation, though the practical catalytic reactions proceed under ambient pressure conditions. However, recent developments of soft x-ray based techniques operating under ambient pressure conditions have opened a door to the in-situ observation of materials under realistic environments. The near-ambient-pressure x-ray photoelectron spectroscopy (NAP-XPS) using synchrotron radiation enables us to observe the chemical states of surfaces of condensed matters under the presence of gas(es) at elevated pressures, which has been hardly conducted with the conventional XPS technique. Furthermore, not only the NAP-XPS but also ambient-pressure compatible soft x-ray core-level spectroscopies, such as near-edge absorption fine structure (NEXAFS) and x-ray emission spectroscopy (XES), have been significantly contributing to the in-situ observations. In this review, first we introduce recent developments of in-situ observations using soft x-ray techniques and current status. Then we present recent new findings on catalytically active surfaces using soft x-ray techniques, particularly focusing on the NAP-XPS technique. Finally we give a perspective on the future direction of this emerging technique.

  1. Quantifying Spatial and Seasonal Variability in Atmospheric Ammonia with In Situ and Space-Based Observations

    NASA Technical Reports Server (NTRS)

    Pinder, Robert W.; Walker, John T.; Bash, Jesse O.; Cady-Pereira, Karen E.; Henze, Daven K.; Luo, Mingzhao; Osterman, Gregory B.; Shepard, Mark W.

    2011-01-01

    Ammonia plays an important role in many biogeochemical processes, yet atmospheric mixing ratios are not well known. Recently, methods have been developed for retrieving NH3 from space-based observations, but they have not been compared to in situ measurements. We have conducted a field campaign combining co-located surface measurements and satellite special observations from the Tropospheric Emission Spectrometer (TES). Our study includes 25 surface monitoring sites spanning 350 km across eastern North Carolina, a region with large seasonal and spatial variability in NH3. From the TES spectra, we retrieve a NH3 representative volume mixing ratio (RVMR), and we restrict our analysis to times when the region of the atmosphere observed by TES is representative of the surface measurement. We find that the TES NH3 RVMR qualitatively captures the seasonal and spatial variability found in eastern North Carolina. Both surface measurements and TES NH3 show a strong correspondence with the number of livestock facilities within 10 km of the observation. Furthermore, we find that TES H3 RVMR captures the month-to-month variability present in the surface observations. The high correspondence with in situ measurements and vast spatial coverage make TES NH3 RVMR a valuable tool for understanding regional and global NH3 fluxes.

  2. Release Timescales of Solar Energetic Particles as inferred from In-situ and Remote Electromagnetic Observations

    NASA Astrophysics Data System (ADS)

    Agueda, Neus

    2015-04-01

    We present a systematic study of the timing and duration of the release processes of near-relativistic (NR; >50 keV) electrons in the low corona. We analyze seven well-observed events using in-situ measurements by both the ACE and Wind spacecraft, and context electromagnetic observations in soft X-rays, radio, hard X-rays and white light. We use an interplanetary transport model to take propagation effects from the source to the observer into account. This allows us to unfold the NR electron release time history in the low corona from in-situ measurements at 1 AU. We obtain that NR electrons observed in interplanetary space appear to be released during either short (<30 min) or long (>2 h) periods. Short release episodes appear to originate in solar flares, in coincidence with the timing of observed type III radio bursts reaching the local plasma line measured at 1 AU. The origin of long release episodes seems to be more intricate. They appear associated with signatures of long acceleration processes in the low corona (long decay of the soft X-ray emission, type IV radio bursts, and time-extended microwave emission).

  3. Airborne observations of cloud properties on HALO during NARVAL

    NASA Astrophysics Data System (ADS)

    Konow, Heike; Hansen, Akio; Ament, Felix

    2016-04-01

    The representation of cloud and precipitation processes is one of the largest sources of uncertainty in climate and weather predictions. To validate model predictions of convective processes over the Atlantic ocean, usually satellite data are used. However, satellite products provide just a coarse view with poor temporal resolution of convective maritime clouds. Aircraft-based observations offer a more detailed insight due to lower altitude and high sampling rates. The research aircraft HALO (High Altitude Long Range Research Aircraft) is operated by the German Aerospace Center (DLR). With a ceiling of 15 km, and a range of 10,000 km and more than 10 hours it is able to reach remote regions and operate from higher altitudes than most other research aircraft. Thus, it provides the unique opportunity to exploit regions of the atmosphere that cannot be easily accessed otherwise. Measurements conducted on HALO provide more detailed insights than achievable from satellite data. Therefore, this measurement platform bridges the gap between previous airborne measurements and satellites. The payload used for this study consists of, amongst others, a suite of passive microwave radiometers, a cloud radar, and a water vapor DIAL. To investigate cloud and precipitation properties of convective maritime clouds, the NARVAL (Next-generation Aircraft Remote-Sensing for Validation Studies) campaign was conducted in winter 2013/2014 out of Barbados and Keflavik (Iceland). This campaign was one of the first that took place on the HALO aircraft. During the experiment's two parts 15 research flights were conducted (8 flights during NARVAL-South out of Barbados to investigate trade-wind cumuli and 7 flights out of Keflavik with focus on mid-latitude cyclonic systems). Flight durations were between five and nine hours, amounting to roughly 118 flight hours overall. 121 dropsondes were deployed. In fall 2016 two additional aircraft campaigns with the same payload will take place: The

  4. Evaluation of Terms in the Water Vapor Budget Using Airborne Dial and In Situ Measurements from the Southern Great Plans 1997 Experiment

    NASA Technical Reports Server (NTRS)

    Senff, Christoph J.; Davis, Kenneth J.; Lenschow, Donald H.; Browell, Edward V.; Ismail, Syed

    1998-01-01

    The Southern Great Plains (SGP97) field experiment was conducted in Oklahoma during June and July 1997 primarily to validate soil moisture retrieval algorithms using microwave radiometer measurements from aircraft as well as in situ surface measurements. One important objective of the SGP97 experiment plan was to examine the effect of soil moisture on the evolution of the atmospheric boundary layer (ABL) and clouds over the Southern Great Plains during the warm season. To support boundary layer studies during SGP97. the NASA Langley Research Center's Lidar Atmospheric Sensing Experiment (LASE) was flown on a NASA-P3 aircraft in conjunction with the Electronically Scanned Thinned Array Radiometer (ESTAR). The LASE instrument is an airborne, downward-looking differential absorption lidar (DIAL) system capable of measuring water vapor concentration as well as aerosol backscatter with high horizontal and vertical resolution in the ABL. Here, we will demonstrate how the LASE data can be used to determine water vapor statistics and most of the water vapor budget terms in the ABL. This information can then be related to spatial variations in soil moisture and the surface energy budget. The extensive surface and aircraft in situ measurements conducted during SGP97 provide information on the ABL that cannot be retrieved from the LASE data alone and also offer an excellent opportunity to validate the remote water vapor budget measurements with LASE.

  5. Validation of satellite overland retrievals of AOD at northern high latitudes with coincident measurements from airborne sunphotometer, lidar, and in situ sensors during ARCTAS

    NASA Astrophysics Data System (ADS)

    Livingston, J. M.; Shinozuka, Y.; Redemann, J.; Russell, P. B.; Ramachandran, S.; Johnson, R. R.; Clarke, A. D.; Howell, S. G.; McNaughton, C.; Freitag, S.; Kapustin, V. N.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Torres, O.; Veefkind, P.; Remer, L. A.; Mattoo, S.; Levy, R. C.; Chu, A. D.; Kahn, R. A.; Davis, M. R.

    2009-12-01

    The 2008 Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) field campaign presented a unique opportunity for validation of satellite retrievals of aerosol optical depth (AOD) over a variety of surfaces at northern high latitudes. In particular, the 14-channel NASA Ames Airborne Tracking Sunphotometer (AATS-14) was operated together with a variety of in-situ and other remote sensors aboard the NASA P-3B research aircraft during both the spring and summer phases of ARCTAS. Among the in-situ sensors were a nephelometer and particle soot absorption photometer (PSAP) operated by University of Hawaii Group for Environmental Aerosol Research (HIGEAR). P-3B science missions included several coincident underflights of the Terra and A-Train satellites during a variety of aerosol loading conditions, including Arctic haze and smoke plumes from boreal forest fires. In this presentation, we will compare AATS-14 AOD spectra, adjusted for the contribution from the layer below the aircraft using the HiGEAR scattering and absorption measurements, with full column AOD retrievals from coincident measurements by satellite sensors such as MISR, MODIS, OMI, and POLDER. We also intend to show comparisons of aerosol extinction derived from AATS-14 measurements during P-3B vertical profiles with coincident measurements from CALIOP aboard the CALIPSO satellite and from the high spectral resolution lidar (HSRL) flown aboard the NASA B-200 aircraft.

  6. Ion cyclotron instability at Io: Hybrid simulation results compared to in situ observations

    NASA Astrophysics Data System (ADS)

    Šebek, Ondřej; Trávníček, Pavel M.; Walker, Raymond J.; Hellinger, Petr

    2016-08-01

    We present analysis of global three-dimensional hybrid simulations of Io's interaction with Jovian magnetospheric plasma. We apply a single-species model with simplified neutral-plasma chemistry and downscale Io in order to resolve the ion kinetic scales. We consider charge exchange, electron impact ionization, and photoionization by using variable rates of these processes to investigate their impact. Our results are in a good qualitative agreement with the in situ magnetic field measurements for five Galileo flybys around Io. The hybrid model describes ion kinetics self-consistently. This allows us to assess the distribution of temperature anisotropies around Io and thereby determine the possible triggering mechanism for waves observed near Io. We compare simulated dynamic spectra of magnetic fluctuations with in situ observations made by Galileo. Our results are consistent with both the spatial distribution and local amplitude of magnetic fluctuations found in the observations. Cyclotron waves, triggered probably by the growth of ion cyclotron instability, are observed mainly downstream of Io and on the flanks in regions farther from Io where the ion pickup rate is relatively low. Growth of the ion cyclotron instability is governed mainly by the charge exchange rate.

  7. Pulsating aurora observed on the ground and in-situ by the Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Lessard, M.; Cohen, I. J.; Denton, R. E.; Engebretson, M. J.; Kletzing, C.; Wygant, J. R.; Bounds, S. R.; Smith, C. W.; MacDowall, R. J.; Kurth, W. S.

    2013-12-01

    Early observations and theory related to pulsating aurora suggested that the electrons that drive this aurora originate from the equatorial region of the magnetosphere and that a likely process that can scatter these electrons would involve chorus waves. Recent satellite observations during pulsating auroral events have provided important "firsts", including evidence of strong correlations between pulsating auroral patches and in-situ lower-band chorus (THEMIS), as well as correlations with energetic electron precipitation in the vicinity of geosynchronous orbit (GOES). These results provide important information regarding particle dynamics, leading to a question about how the chorus might be driven. We present observations of the Van Allen Probes in conjunction with a pulsating aurora event, as confirmed by observations on the ground. The in-situ data again show the presence of lower-band chorus. However, magnetic and electric field data also show that the wave bursts coincide with an apparent poloidal field-line resonance, begging the question of whether the resonance might be responsible for driving the VLF waves.

  8. Developing a Scalable Remote Sampling Design for the NEON Airborne Observation Platform (AOP)

    NASA Astrophysics Data System (ADS)

    Musinsky, J.; Wasser, L. A.; Kampe, T. U.; Leisso, N.; Krause, K.; Petroy, S. B.; Cawse-Nicholson, K.; van Aardt, J. A.; Serbin, S.

    2013-12-01

    The National Ecological Observatory Network (NEON) airborne observation platform (AOP) will collect co-registered high-resolution hyperspectral imagery, discrete and waveform LiDAR, and high-resolution digital photography for more than 60 terrestrial and 23 aquatic sites spread across the continental United States, Puerto Rico, Alaska and Hawaii on an annual basis over the next 30 years. These data, to be made freely available to the public, will facilitate the scaling of field-based biological, physical and chemical measurements to regional and continental scales, enabling a better understanding of the relationships between climate variability and change, land use change and invasive species, and their ecological consequences in areas not directly sampled by the NEON facilities. However, successful up-scaling of in situ measurements requires a flight sampling design that captures environmental heterogeneity and diversity (i.e., ecological and topographic gradients), is sensitive to temporal system variation (e.g., phenology), and can respond to major disturbance events. Alignment of airborne campaigns - composed of two payloads for nominal science acquisitions and one payload for PI-driven rapid-response campaigns -- with other ground, airborne (e.g., AVIRIS) and satellite (e.g., Landsat, MODIS) collections will further facilitate scaling between sensors and data sources of varying spatial and spectral resolution and extent. This presentation will discuss the approach, challenges and future goals associated with the development of NEON AOP's sampling design, using examples from the 2013 nominal flight campaigns in the Central Plains (NEON Domain 10) and the Pacific Southwest (Domain 17), and the rapid response flight campaign of the High Park Fire site outside of Fort Collins, CO. Determination of the specific flight coverage areas for each campaign involved analysis of the landscape scale ecological, geophysical and bioclimatic attributes and trends most closely

  9. In-situ observation and atomic resolution imaging of the ion irradiation induced amorphisation of graphene

    PubMed Central

    Pan, C.-T.; Hinks, J. A.; Ramasse, Q. M.; Greaves, G.; Bangert, U.; Donnelly, S. E.; Haigh, S. J.

    2014-01-01

    Ion irradiation has been observed to induce a macroscopic flattening and in-plane shrinkage of graphene sheets without a complete loss of crystallinity. Electron diffraction studies performed during simultaneous in-situ ion irradiation have allowed identification of the fluence at which the graphene sheet loses long-range order. This approach has facilitated complementary ex-situ investigations, allowing the first atomic resolution scanning transmission electron microscopy images of ion-irradiation induced graphene defect structures together with quantitative analysis of defect densities using Raman spectroscopy. PMID:25284688

  10. In-situ observation and atomic resolution imaging of the ion irradiation induced amorphisation of graphene.

    PubMed

    Pan, C-T; Hinks, J A; Ramasse, Q M; Greaves, G; Bangert, U; Donnelly, S E; Haigh, S J

    2014-01-01

    Ion irradiation has been observed to induce a macroscopic flattening and in-plane shrinkage of graphene sheets without a complete loss of crystallinity. Electron diffraction studies performed during simultaneous in-situ ion irradiation have allowed identification of the fluence at which the graphene sheet loses long-range order. This approach has facilitated complementary ex-situ investigations, allowing the first atomic resolution scanning transmission electron microscopy images of ion-irradiation induced graphene defect structures together with quantitative analysis of defect densities using Raman spectroscopy. PMID:25284688

  11. In situ Microscopic Observation of Sodium Deposition/Dissolution on Sodium Electrode

    PubMed Central

    Yui, Yuhki; Hayashi, Masahiko; Nakamura, Jiro

    2016-01-01

    Electrochemical sodium deposition/dissolution behaviors in propylene carbonate-based electrolyte solution were observed by means of in situ light microscopy. First, granular sodium was deposited at pits in a sodium electrode in the cathodic process. Then, the sodium particles grew linearly from the electrode surface, becoming needle-like in shape. In the subsequent anodic process, the sodium dissolved near the base of the needles on the sodium electrode and the so-called “dead sodium” broke away from the electrode. The mechanisms of electrochemical sodium deposition and dissolution on a copper electrode were similar to those on the sodium electrode. PMID:26925554

  12. In-situ observation of atomic self-organization processes in Xe nanocrystals embedded in Al.

    SciTech Connect

    Mitsuishi, K.; Song, M.; Furuya, K.; Birtcher, R. C.; Allen, C. W.; Donnelly, S. E.

    1998-03-10

    Self-organization processes in Xe nanocrystals embedded in Al are observed with in-situ high-resolution electron microscopy. Under electron irradiation, stacking fault type defects are produced in Xe nanocrystals. The defects recover in a layer by layer manner. Detailed analysis of the video reveals that the displacement of Xe atoms in the stacking fault was rather small for the Xe atoms at boundary between Xe and Al, suggesting the possibility of the stacking fault in Xe precipitate originating inside of precipitate, not at the Al/Xe interface.

  13. Observations of globular membranes and apparent elementary particles in rat mitochondria, in situ.

    PubMed

    Baur, P S; Stacey, T R

    1978-01-01

    Ultrastructural details of rat skeletal muscle, fixed in a PIPES-buffered glutaraldehyde solution, included the globular configuration of the outer and inner mitochondrial membranes as well as small transparent particles (80--100A diameter) distributed throughout the matrix of these organelles. The size of these particles and their intimate relationship with the innermost surface of the cristae suggests that they may represent an in situ visualization of the elementary particles once reported in intact cells and frequently observed in negatively stained mitochondrial preparations. The membrane configurations and particles were not discernable in these tissues when a phosphate buffer system was used in the fixation regimen. PMID:725795

  14. Energization of Oxygen Ions at Mars: Comparison of a Global Hybrid Model to In Situ Observations

    NASA Astrophysics Data System (ADS)

    Jarvinen, R.; Brain, D. A.; Fedorov, A.; Holmstrom, M.; Modolo, R.

    2015-12-01

    We study the energization of planetary oxygen ions escaping from the atmosphere of Mars in a global hybrid model for the Mars-solar wind interaction. In the hybrid approach ions are modelled as particles moving under the Lorentz force and electrons are a charge-neutralizing fluid. Thus, electric and magnetic field are self-consistently coupled with ion dynamics. We identify ion energization regions in the induced magnetosphere of Mars in the model. Further, we study electric and magnetic fields associated with the ion acceleration processes. Finally, we compare our simulation results to in situ particle and magnetic field observations on the MAVEN and Mars Express missions.

  15. A Reevaluation of Airborne HO(x) Observations from NASA Field Campaigns

    NASA Technical Reports Server (NTRS)

    Olson, Jennifer; Crawford, James H.; Chen, Gao; Brune, William H.; Faloona, Ian C.; Tan, David; Harder, Hartwig; Martinez, Monica

    2006-01-01

    In-situ observations of tropospheric HO(x) (OH and HO2) obtained during four NASA airborne campaigns (SUCCESS, SONEX, PEM-Tropics B and TRACE-P) are reevaluated using the NASA Langley time-dependent photochemical box model. Special attention is given to previously diagnosed discrepancies between observed and predicted HO2 which increase with higher NO(x) levels and at high solar zenith angles. This analysis shows that much of the model discrepancy at high NO(x) during SUCCESS can be attributed to modeling observations at time-scales too long to capture the nonlinearity of HO(x) chemistry under highly variable conditions for NO(x). Discrepancies at high NO(x) during SONEX can be moderated to a large extent by complete use of all available precursor observations. Differences in kinetic rate coefficients and photolysis frequencies available for previous studies versus current recommendations also explain some of the disparity. Each of these causes is shown to exert greater influence with increasing NO(x) due to both the chemical nonlinearity between HO(x) and NO(x) and the increased sensitivity of HO(x) to changes in sources at high NO(x). In contrast, discrepancies at high solar zenith angles will persist until an adequate nighttime source of HO(x) can be identified. It is important to note that this analysis falls short of fully eliminating the issue of discrepancies between observed and predicted HO(x) for high NO(x) environments. These discrepancies are not resolved with the above causes in other data sets from ground-based field studies. Nevertheless, these results highlight important considerations in the application of box models to observationally based predictions of HO(x) radicals.

  16. In situ observation of the molecular ordering in the lubricating point contact area

    NASA Astrophysics Data System (ADS)

    Zhang, Shaohua; Liu, Yuhong; Luo, Jianbin

    2014-07-01

    The organization of lubricant molecules confined between two solid surfaces when the lubricant film thickness is at the nanoscale is unknown. In this work, an ordering process of nematic liquid crystal molecules is observed by in situ polarized Raman spectroscopy of the lubricated point contact area. Our experimental results indicate that 4-n-pentyl-4'-cyanobiphenyl liquid crystal molecules orient along the rotation direction when the linear speed exceeds 12.6 mm/s, and the degree of order increases with linear speed. The relationship between the observed orientation and physical properties of the lubricant film is investigated. Isotropic orientation is observed at the outlet area of the contact region. The orientation behavior of liquid crystal molecules in a confined area is observed and the relationship between lubrication conditions and molecular orientation is discussed.

  17. In situ observation of elementary growth processes of protein crystals by advanced optical microscopy.

    PubMed

    Sazaki, Gen; Van Driessche, Alexander E S; Dai, Guoliang; Okada, Masashi; Matsui, Takuro; Otálora, Fermin; Tsukamoto, Katsuo; Nakajima, Kazuo

    2012-07-01

    To start systematically investigating the quality improvement of protein crystals, the elementary growth processes of protein crystals must be first clarified comprehensively. Atomic force microscopy (AFM) has made a tremendous contribution toward elucidating the elementary growth processes of protein crystals and has confirmed that protein crystals grow layer by layer utilizing kinks on steps, as in the case of inorganic and low-molecular-weight compound crystals. However, the scanning of the AFM cantilever greatly disturbs the concentration distribution and solution flow in the vicinity of growing protein crystals. AFM also cannot visualize the dynamic behavior of mobile solute and impurity molecules on protein crystal surfaces. To compensate for these disadvantages of AFM, in situ observation by two types of advanced optical microscopy has been recently performed. To observe the elementary steps of protein crystals noninvasively, laser confocal microscopy combined with differential interference contrast microscopy (LCM-DIM) was developed. To visualize individual mobile protein molecules, total internal reflection fluorescent (TIRF) microscopy, which is widely used in the field of biological physics, was applied to the visualization of protein crystal surfaces. In this review, recent progress in the noninvasive in situ observation of elementary steps and individual mobile protein molecules on protein crystal surfaces is outlined.

  18. In situ observation of structural transformation of gold nanorods under pulsed laser irradiation in an HVEM.

    PubMed

    Sumimoto, Nao; Nakao, Koichiro; Yamamoto, Tomokazu; Yasuda, Kazuhiro; Matsumura, Syo; Niidome, Yasuro

    2014-08-01

    A pulsed laser light illumination system was attached to a high-voltage electron microscope (HVEM) for in situ observation of light-induced behaviors of nano objects. The wavelength λ of emitted laser pulses was 1064, 532 or 266 nm, and the pulse duration was 6-8 ns. Using this combined HVEM system, we observed the deformation behavior of gold nanorods irradiated by a pulsed laser (λ = 1064 nm) at an intensity of 310 J m(-2) pulse or higher. A single shot of pulsed laser reduced the aspect ratio of the gold nanorods from 5 to a much smaller value. The extent of the reduction increased at higher laser intensities. However, at 310 J m(-2) pulse(-1), additional pulsed shots induced limited further deformation. The mean aspect ratio approximated to 2.5 even after irradiation with 7 pulses (total fluence exceeding 2 MJ m(-2)). In situ high resolution transmission electron microscopy (HRTEM) observation revealed that deformation was accompanied by total atomic restructuring of the nanorod interiors.

  19. A century of ocean warming on Florida Keys coral reefs: historic in situ observations

    USGS Publications Warehouse

    Kuffner, Ilsa B.; Lidz, Barbara H.; Hudson, J. Harold; Anderson, Jeffery S.

    2015-01-01

    There is strong evidence that global climate change over the last several decades has caused shifts in species distributions, species extinctions, and alterations in the functioning of ecosystems. However, because of high variability on short (i.e., diurnal, seasonal, and annual) timescales as well as the recency of a comprehensive instrumental record, it is difficult to detect or provide evidence for long-term, site-specific trends in ocean temperature. Here we analyze five in situ datasets from Florida Keys coral reef habitats, including historic measurements taken by lighthouse keepers, to provide three independent lines of evidence supporting approximately 0.8 °C of warming in sea surface temperature (SST) over the last century. Results indicate that the warming observed in the records between 1878 and 2012 can be fully accounted for by the warming observed in recent decades (from 1975 to 2007), documented using in situ thermographs on a mid-shore patch reef. The magnitude of warming revealed here is similar to that found in other SST datasets from the region and to that observed in global mean surface temperature. The geologic context and significance of recent ocean warming to coral growth and population dynamics are discussed, as is the future prognosis for the Florida reef tract.

  20. Validation of EGSIEM gravity field products with globally distributed in situ ocean bottom pressure observations

    NASA Astrophysics Data System (ADS)

    Poropat, Lea; Bergmann-Wolf, Inga; Flechtner, Frank; Dobslaw, Henryk

    2016-04-01

    Time variable global gravity field models that are processed by different research institutions all across Europe are currently compared and subsequently combined within the "European Gravity Field Service for Improved Emergency Management (EGSIEM)" project funded by the European Union. To objectively assess differences between the results from different groups, and also to evaluate the impact of changes in the data processing at an individual institution in preparation of a new data release, a validation of the final GRACE gravity fields against independent observations is required. 
For such a validation, we apply data from a set of globally distributed ocean bottom pressure sensors. The in situ observations have been thoroughly revised for outliers, instrumental drift and jumps, and were additionally reduced for tides. GRACE monthly mean solutions are then validated with the monthly resampled in situ observations. The validation typically concentrates on seasonal to interannual signals, but in case of GRACE-based series with daily sampling available from, e.g., Kalman Smoother Solutions, also sub-monthly signal variability can be assessed.

  1. High-temperature in situ crystallographic observation of reversible gas sorption in impermeable organic cages

    PubMed Central

    Baek, Seung Bin; Moon, Dohyun; Graf, Robert; Cho, Woo Jong; Park, Sung Woo; Yoon, Tae-Ung; Cho, Seung Joo; Hwang, In-Chul; Bae, Youn-Sang; Spiess, Hans W.; Lee, Hee Cheon; Kim, Kwang S.

    2015-01-01

    Crystallographic observation of adsorbed gas molecules is a highly difficult task due to their rapid motion. Here, we report the in situ single-crystal and synchrotron powder X-ray observations of reversible CO2 sorption processes in an apparently nonporous organic crystal under varying pressures at high temperatures. The host material is formed by hydrogen bond network between 1,3,5-tris-(4-carboxyphenyl)benzene (H3BTB) and N,N-dimethylformamide (DMF) and by π–π stacking between the H3BTB moieties. The material can be viewed as a well-ordered array of cages, which are tight packed with each other so that the cages are inaccessible from outside. Thus, the host is practically nonporous. Despite the absence of permanent pathways connecting the empty cages, they are permeable to CO2 at high temperatures due to thermally activated molecular gating, and the weakly confined CO2 molecules in the cages allow direct detection by in situ single-crystal X-ray diffraction at 323 K. Variable-temperature in situ synchrotron powder X-ray diffraction studies also show that the CO2 sorption is reversible and driven by temperature increase. Solid-state magic angle spinning NMR defines the interactions of CO2 with the organic framework and dynamic motion of CO2 in cages. The reversible sorption is attributed to the dynamic motion of the DMF molecules combined with the axial motions/angular fluctuations of CO2 (a series of transient opening/closing of compartments enabling CO2 molecule passage), as revealed from NMR and simulations. This temperature-driven transient molecular gating can store gaseous molecules in ordered arrays toward unique collective properties and release them for ready use. PMID:26578758

  2. Airborne lidar and radiometric observations of PBL- and low clouds

    NASA Technical Reports Server (NTRS)

    Flamant, P. H.; Valentin, R.; Pelon, J.

    1992-01-01

    Boundary layer- and low altitude clouds over open ocean and continent areas have been studied during several field campaigns since mid-1990 using the French airborne backscatter lidar LEANDRE in conjunction with on-board IR and visible radiometers. LEANDRE is an automatic system, and a modification of the instrumental parameters, when airborne, is computer controlled through an operator keyboard. The vertical range squared lidar signals and instrument status are displayed in real time on two dedicated monitors. The lidar is used either down- or up-looking while the aircraft is flying above or below clouds. A switching of the viewing configuration takes about a minute. The lidar measurements provide a high resolution description of cloud morphology and holes in cloud layers. The flights were conducted during various meteorological conditions on single or multilayer stratocumulus and cumulus decks. Analysis on a single shot basis of cloud top (or bottom) altitude and a plot of the corresponding histogram allows one to determine a probability density function (PDF). The preliminary results show the PDFs for cloud top are not Gaussian and symmetric about the mean value. The skewness varies with atmospheric conditions. An example of results recorded over the Atlantic ocean near Biarritz is displayed, showing: (1) the range squared lidar signals as a function of time (here 100 s corresponds to about 8 km, 60 shots are averaged on horizontal); the Planetary Boundary Layer (PBL) - up to 600 m - is observed at the beginning of the leg as well as on surface returns, giving an indication of the porosity; (2) the cloud top altitude variation between 2.4 to 2.8 km during the 150 to 320 s section; and (3) the corresponding PDF. Similar results are obtained on stratocumulus over land. Single shot measurements can be used also to determine an optical porosity at a small scale as well as a fractional cloudiness at a larger scale. A comparison of cloud top altitude retrieved from

  3. Sensor Web Standards for Interoperability between in-situ Earth Observation Networks

    NASA Astrophysics Data System (ADS)

    Rieke, Matthes; Casas, Raquel; Garcia, Oscar; Jirka, Simon; Menard, Lionel; Ranchin, Thierry; Stasch, Christoph; Wald, Lucien

    2016-04-01

    Existing earth observation networks deliver a multitude of in-situ data capturing the state of the earth. The data sets delivered by these networks are of high value for scientists and other stakeholders from different domains and backgrounds. However, the access and integration of the data sets made available by these earth observation networks are often complex as different data delivery methods and formats are used. To strengthen and broaden the use of the available data sets, it is important to offer efficient methods for accessing the data from different types of applications (e.g. for data analysis or data visualisation). The Sensor Web Enablement (SWE) standards of the Open Geospatial Consortium (OGC) are adopted by more and more stakeholders and may serve as a good baseline for increasing the interoperability of data flows. This harmonisation of standards is also one of the core objectives of the ENEON (European Network of Earth Observation Networks) initiative promoted by the European Horizon 2020 project ConnectinGEO (Coordinating an Observation Network of Networks EnCompassing saTellite and IN-situ to fill the Gaps in European Observations). In this contribution, we illustrate how domain-specific profiles of the OGC SWE standards may help to increase interoperability within specific domains. This includes for example the specification of SWE profiles for hydrology (e.g. resulting from the European GEOWOW project) or the e-Reporting SWE profiles for ambient air quality in Europe. Another example are SWE profiles for oceanology which are currently developed by several projects such as BRIDGES, Eurofleets 2, FixO3, IOOS, Jerico-Next, NeXOS, ODIP II, and SeaDataNet (e.g. using RelaxNG and Schematron for defining a structure of SWE encoded messages to be applied in tools, vessels and fixed stations). Finally, a Sensor Web-based scenario from the ConnectinGEO project covering energy and solar radiation will be introduced that connects data providers and users

  4. Earth's ion upflow associated with polar cap patches: Global and in situ observations

    NASA Astrophysics Data System (ADS)

    Zhang, Qing-He; Zong, Qiu-Gang; Lockwood, Michael; Heelis, Roderick A.; Hairston, Marc; Liang, Jun; McCrea, Ian; Zhang, Bei-Chen; Moen, Jøran; Zhang, Shun-Rong; Zhang, Yong-Liang; Ruohoniemi, J. Michael; Lester, Mark; Thomas, Evan G.; Liu, Rui-Yuan; Dunlop, Malcolm W.; Liu, Yong C.-M.; Ma, Yu-Zhang

    2016-03-01

    We report simultaneous global monitoring of a patch of ionization and in situ observation of ion upflow at the center of the polar cap region during a geomagnetic storm. Our observations indicate strong fluxes of upwelling O+ ions originating from frictional heating produced by rapid antisunward flow of the plasma patch. The statistical results from the crossings of the central polar cap region by Defense Meteorological Satellite Program F16-F18 from 2010 to 2013 confirm that the field-aligned flow can turn upward when rapid antisunward flows appear, with consequent significant frictional heating of the ions, which overcomes the gravity effect. We suggest that such rapidly moving patches can provide an important source of upwelling ions in a region where downward flows are usually expected. These observations give new insight into the processes of ionosphere-magnetosphere coupling.

  5. In-Situ Observation of Horizontal Centrifugal Casting using a High-Speed Camera

    NASA Astrophysics Data System (ADS)

    Esaka, Hisao; Kawai, Kohsuke; Kaneko, Hiroshi; Shinozuka, Kei

    2012-07-01

    In order to understand the solidification process of horizontal centrifugal casting, experimental equipment for in-situ observation using transparent organic substance has been constructed. Succinonitrile-1 mass% water alloy was filled in the round glass cell and the glass cell was completely sealed. To observe the movement of equiaxed grains more clearly and to understand the effect of movement of free surface, a high-speed camera has been installed on the equipment. The most advantageous point of this equipment is that the camera rotates with mold, so that one can observe the same location of the glass cell. Because the recording rate could be increased up to 250 frames per second, the quality of movie was dramatically modified and this made easier and more precise to pursue the certain equiaxed grain. The amplitude of oscillation of equiaxed grain ( = At) decreased as the solidification proceeded.

  6. Four-Component Borehole Strain Meter: Observation and in-situ Calibration

    NASA Astrophysics Data System (ADS)

    Qiu, Z.; Shi, Y.; Ouyang, Z.

    2004-12-01

    Borehole strain meters are a key component of some important geo-scientific projects, such as PBO, to monitor seismic and aseismic tectonic strain phenomena. Observation using a four-component borehole strain meter, namely Ouyang borehole strain meter, has been kept continuous at Changping station, Beijing, for years. The plane strain changes are obtained at the depth of 120m and from 4 horizontal measurements, spaced 45 degrees apart, of the radial deformation of the borehole in which the instrument is installed. The challenge is that, according to the theory of elasticity, the sum of any two measurements perpendicular to each other should be the same as related to areal strain. The observation at Changping agrees pretty well with this rule and, with a relative in-situ calibration correction to the transducer factors based on the rule, the agreements can be yet much improved. Since the transducers were arranged well in the orientations of North, East, North West and North East, respectively, instrument shear strains can be simply given as the differences of the two correspondent perpendicular measurements. By applying theoretic Earth strain tide as a reference signal, in-situ absolute calibration can be carried out and the proportionality constants c and d, and the orientation error as well, can be calculated separately. Fore-component borehole strain meter has the advantages of giving more accurate and more reliable data for Earth strain and of easier processing as compared to three-component borehole strain meter.

  7. In situ observation of quasimelting of diamond and reversible graphite-diamond phase transformations.

    PubMed

    Huang, J Y

    2007-08-01

    Because of technique difficulties in achieving the extreme high-pressure and high-temperature (HPHT) simultaneously, direct observation of the structures of carbon at extreme HPHT conditions has not been possible. Banhart and Ajayan discovered remarkably that carbon onions can act as nanoscopic pressure cells to generate high pressures. By heating carbon onions to approximately 700 degrees C and under electron beam irradiation, the graphite-to-diamond transformation was observed in situ by transmission electron microscopy (TEM). However, the highest achievable temperature in a TEM heating holder is less than 1000 degrees C. Here we report that, by using carbon nanotubes as heaters and carbon onions as high-pressure cells, temperatures higher than 2000 degrees C and pressures higher than 40 GPa were achieved simultaneously in carbon onions. At such HPHT conditions and facilitated by electron beam irradiation, the diamond formed in the carbon onion cores frequently changed its shape, size, orientation, and internal structure and moved like a fluid, implying that it was in a quasimelting state. The fluctuation between the solid phase of diamond and the fluid/amorphous phase of diamond-like carbon, and the changes of the shape, size, and orientation of the solid diamond, were attributed to the dynamic crystallization of diamond crystal from the quasimolten state and the dynamic graphite-diamond phase transformations. Our discovery offers unprecedented opportunities to studying the nanostructures of carbon at extreme conditions in situ and at an atomic scale.

  8. Bioturbation in a declining oxygen environment, in situ observations from Wormcam.

    PubMed

    Sturdivant, S Kersey; Díaz, Robert J; Cutter, George R

    2012-01-01

    Bioturbation, the displacement and mixing of sediment particles by fauna or flora, facilitates life supporting processes by increasing the quality of marine sediments. In the marine environment bioturbation is primarily mediated by infaunal organisms, which are susceptible to perturbations in their surrounding environment due to their sedentary life history traits. Of particular concern is hypoxia, dissolved oxygen (DO) concentrations ≤2.8 mg l(-1), a prevalent and persistent problem that affects both pelagic and benthic fauna. A benthic observing system (Wormcam) consisting of a buoy, telemetering electronics, sediment profile camera, and water quality datasonde was developed and deployed in the Rappahannock River, VA, USA, in an area known to experience seasonal hypoxia from early spring to late fall. Wormcam transmitted a time series of in situ images and water quality data, to a website via wireless internet modem, for 5 months spanning normoxic and hypoxic periods. Hypoxia was found to significantly reduce bioturbation through reductions in burrow lengths, burrow production, and burrowing depth. Although infaunal activity was greatly reduced during hypoxic and near anoxic conditions, some individuals remained active. Low concentrations of DO in the water column limited bioturbation by infaunal burrowers and likely reduced redox cycling between aerobic and anaerobic states. This study emphasizes the importance of in situ observations for understanding how components of an ecosystem respond to hypoxia. PMID:22493701

  9. Bioturbation in a declining oxygen environment, in situ observations from Wormcam.

    PubMed

    Sturdivant, S Kersey; Díaz, Robert J; Cutter, George R

    2012-01-01

    Bioturbation, the displacement and mixing of sediment particles by fauna or flora, facilitates life supporting processes by increasing the quality of marine sediments. In the marine environment bioturbation is primarily mediated by infaunal organisms, which are susceptible to perturbations in their surrounding environment due to their sedentary life history traits. Of particular concern is hypoxia, dissolved oxygen (DO) concentrations ≤2.8 mg l(-1), a prevalent and persistent problem that affects both pelagic and benthic fauna. A benthic observing system (Wormcam) consisting of a buoy, telemetering electronics, sediment profile camera, and water quality datasonde was developed and deployed in the Rappahannock River, VA, USA, in an area known to experience seasonal hypoxia from early spring to late fall. Wormcam transmitted a time series of in situ images and water quality data, to a website via wireless internet modem, for 5 months spanning normoxic and hypoxic periods. Hypoxia was found to significantly reduce bioturbation through reductions in burrow lengths, burrow production, and burrowing depth. Although infaunal activity was greatly reduced during hypoxic and near anoxic conditions, some individuals remained active. Low concentrations of DO in the water column limited bioturbation by infaunal burrowers and likely reduced redox cycling between aerobic and anaerobic states. This study emphasizes the importance of in situ observations for understanding how components of an ecosystem respond to hypoxia.

  10. Direct observation of graphene growth and associated copper substrate dynamics by in situ scanning electron microscopy.

    PubMed

    Wang, Zhu-Jun; Weinberg, Gisela; Zhang, Qiang; Lunkenbein, Thomas; Klein-Hoffmann, Achim; Kurnatowska, Michalina; Plodinec, Milivoj; Li, Qing; Chi, Lifeng; Schloegl, R; Willinger, Marc-Georg

    2015-02-24

    This work highlights the importance of in situ experiments for an improved understanding of graphene growth on copper via metal-catalyzed chemical vapor deposition (CVD). Graphene growth inside the chamber of a modified environmental scanning electron microscope under relevant low-pressure CVD conditions allows visualizing structural dynamics of the active catalyst simultaneously with graphene nucleation and growth in an unparalleled way. It enables the observation of a complete CVD process from substrate annealing through graphene nucleation and growth and, finally, substrate cooling in real time and nanometer-scale resolution without the need of sample transfer. A strong dependence of surface dynamics such as sublimation and surface premelting on grain orientation is demonstrated, and the influence of substrate dynamics on graphene nucleation and growth is presented. Insights on the growth mechanism are provided by a simultaneous observation of the growth front propagation and nucleation rate. Furthermore, the role of trace amounts of oxygen during growth is discussed and related to graphene-induced surface reconstructions during cooling. Above all, this work demonstrates the potential of the method for in situ studies of surface dynamics on active metal catalysts. PMID:25584770

  11. Direct observation of ferroelectric domain switching in varying electric field regimes using in situ TEM.

    PubMed

    Winkler, C R; Damodaran, A R; Karthik, J; Martin, L W; Taheri, M L

    2012-11-01

    In situ Transmission Electron Microscopy (TEM) techniques can potentially fill in gaps in the current understanding interfacial phenomena in complex oxides. Select multiferroic oxide materials, such as BiFeO(3) (BFO), exhibit ferroelectric and magnetic order, and the two order parameters are coupled through a quantum-mechanical exchange interaction. The magneto-electric coupling in BFO allows control of the ferroelectric and magnetic domain structures via applied electric fields. Because of these unique properties, BFO and other magneto-electric multiferroics constitute a promising class of materials for incorporation into devices such as high-density ferroelectric and magnetoresistive memories, spin valves, and magnetic field sensors. The magneto-electric coupling in BFO is mediated by volatile ferroelastically switched domains that make it difficult to incorporate this material into devices. To facilitate device integration, an understanding of the microstructural factors that affect ferroelastic relaxation and ferroelectric domain switching must be developed. In this article, a method of viewing ferroelectric (and ferroelastic) domain dynamics using in situ biasing in TEM is presented. The evolution of ferroelastically switched ferroelectric domains in BFO thin films during many switching cycles is investigated. Evidence of partial domain nucleation, propagation, and switching even at applied electric fields below the estimated coercive field is revealed. Our observations indicate that the occurrence of ferroelastic relaxation in switched domains and the stability of these domains is influenced the applied field as well as the BFO microstructure. These biasing experiments provide a real time view of the complex dynamics of domain switching and complement scanning probe techniques. Quantitative information about domain switching under bias in ferroelectric and multiferroic materials can be extracted from in situ TEM to provide a predictive tool for future device

  12. Ionospheric Cubeswarm Concept Study: using low-resource instrumentation for truly multipoint in situ ionospheric observations

    NASA Astrophysics Data System (ADS)

    Hampton, D.; Lynch, K. A.; Earle, G. D.; Mannucci, A. J.; Clayton, R.; Fisher, L. E.; Fernandes, P. A.; Roberts, M.; Zettergren, M. D.

    2015-12-01

    Magnetosphere-ionosphere coupling currents close in the nightside lower ionosphere. These spatially inhomogeneous and time varying volume currents are difficult to capture with in situ observations. Our understanding of M-I coupling systems is limited by our understanding of the actual structure of ionospheric current closure. A path forward includes assimilation of a variety of data sets into increasingly capable ionospheric models. While each data set provides only a piece of the picture, the assimilation process allows optimal use of each piece.An important development for the necessary in situ observations involves making them truly multi-point, and therefore, low-resource. For thermal particle observations, the high densities of the lower ionosphere allow the use of low-gain (current-sensing rather than particle-counting) particle sensors. One observational goal is the definition of the actual structure of ionospheric closure currents. This can be approached with a number of different measurement techniques, in tandem with an ionospheric model, since the closure currents need to follow the rules of electrodynamics and current continuity. Low resource thermal plasma sensors such as retarding potential analyzers and drift meters can provide valuable measurements of plasma parameters, including density and plasma flow, without the need for high voltages or deployable boom systems. These low-resource measurements, which can be reproduced on arrays of in situ observation platforms, used in tandem with proper plasma physics interpretation of their signatures in the disturbed observing environment, and as part of an assimilated data set into an ionospheric model, can allow us to progress in our understanding of ionospheric structuring and its effects on auroral coupling. Now, with increasingly capable multipoint arrays of spacecraft, and quantitative 2D-with-time context from cameras and imagery, we are moving toward truly multipoint studies of the system

  13. In Situ Observations of the Microphysical Properties of Subvisible Cirrus during CR- AVE

    NASA Astrophysics Data System (ADS)

    Lawson, P.; Baker, B.; Pilson, B.; Mo, Q.; Jensen, E.

    2006-12-01

    In situ microphysical observations of subvisible cirrus between 8 degrees north latitude and the equator were collected using the NASA WB-57F research aircraft during the Costa Rica - Aura Validation Experiment (CR- AVE) in January 2006. Subvisible cirrus was commonly observed between 75 and 85 C (about 16 and 18 km). The observations included ice particle size, shape, concentration and relative humidity. Instrumentation included a cloud particle imager (CPI), a 2D-S (stereo) probe, a forward and backward scattering probe (CAS) and a tunable diode laser (TDL) water vapor probe. These are the first in situ observations that include a large dataset of digital images of the size and shape of ice particles in tropical subvisible cirrus. The images reveal that 84 percent of the ice particles are quasi-spherical in shape, with only a small percentage of the crystals exhibiting crystalline shapes (e.g., plates and columns), and virtually no trigonal particles, contrary to the only other crystal shape measurements collected in 1973. The particle size distribution suggests a monotonic distribution ranging from a few microns out to 120 microns in diameter. In the denser regions of cloud, mean particle concentrations were on the order of 20 to 40 per liter, mean extinction 0.004 inverse kilometers, and mean ice water content 0.02 mg per cubic meter. The ice particles are almost always observed when the ambient relative humidity is between 140 and 200 percent w.r.t. ice. Particle growth simulations suggest that ice particles in subvisible cirrus require very high (order 200 percent ice saturation) relative humidity to grow to 100 microns. The unique ice particle measurements in subvisible cirrus are useful in constraining water vapor measurements, validation of satellite retrievals and in parameterizations of radiation models.

  14. In-situ observation of volume expansion behavior of a silicon particle in various electrolytes

    NASA Astrophysics Data System (ADS)

    Nishikawa, Kei; Moon, Jinhee; Kanamura, Kiyoshi

    2016-01-01

    The understanding of volume change behavior of a silicon particle is necessary to design a new negative electrode using silicon active materials. Here, the drastic volume expansion behavior of a silicon particle with μm-size was in-situ observed in order to find apparent volume expansion ratio during the first lithiation in several kinds of electrolytes by using single particle measurement technique. This technique is very useful not only to find the intrinsic electrochemical properties but also to observe the volume change behavior of one electrode active materials particle. The apparent volume expansion ratio of a silicon particle was larger than theoretical expectation because the measured silicon particles were secondary particles which contained some space between the primary particles. In addition, the volume expansion behavior during the first charging was independent on the Li salt, solvents and the applied charging current density.

  15. Optimization of NOx emissions in Yangtze Delta Region using in-situ observations

    NASA Astrophysics Data System (ADS)

    Wang, Hengmao; Jiang, Fei; Jiang, Ziqiang; Liu, Jane; Chen, Jing Ming; Ju, Weimin

    2016-04-01

    Well quantified NOx emissions are essential for air quality forecasting and air pollution mitigation. The traditional "bottom-up" estimates of NOx emissions, using activity data and emission factors, are subject to large uncertainties, especially in China. Inverse modelling, often referred to as "top-down" approach, using atmospheric observations made from satellites and ground stations, provides an effective means to optimize bottom-up NOx emission inventory. The rapid expansion of air quality monitoring network in China offers an opportunity to constrain NOx emissions using in-situ ground measurements. We explore the potential of using NO2 observations from the air quality monitoring network to improve NOx emissions estimates in China. The four dimensional variational data assimilation (4DVAR) scheme in the Community Multi-scale Air Quality (CMAQ) adjoint model is implemented to infer NOx emissions in Yangtze Delta Region at 12 km resolution. The optimized NOx emissions are presented. The uncertainly reduction of estimates is analyzed and discussed.

  16. Groundwater quality and depletion in the Indo-Gangetic Basin mapped from in situ observations

    NASA Astrophysics Data System (ADS)

    MacDonald, A. M.; Bonsor, H. C.; Ahmed, K. M.; Burgess, W. G.; Basharat, M.; Calow, R. C.; Dixit, A.; Foster, S. S. D.; Gopal, K.; Lapworth, D. J.; Lark, R. M.; Moench, M.; Mukherjee, A.; Rao, M. S.; Shamsudduha, M.; Smith, L.; Taylor, R. G.; Tucker, J.; van Steenbergen, F.; Yadav, S. K.

    2016-10-01

    Groundwater abstraction from the transboundary Indo-Gangetic Basin comprises 25% of global groundwater withdrawals, sustaining agricultural productivity in Pakistan, India, Nepal and Bangladesh. Recent interpretations of satellite gravity data indicate that current abstraction is unsustainable, yet these large-scale interpretations lack the spatio-temporal resolution required to govern groundwater effectively. Here we report new evidence from high-resolution in situ records of groundwater levels, abstraction and groundwater quality, which reveal that sustainable groundwater supplies are constrained more by extensive contamination than depletion. We estimate the volume of groundwater to 200 m depth to be >20 times the combined annual flow of the Indus, Brahmaputra and Ganges, and show the water table has been stable or rising across 70% of the aquifer between 2000 and 2012. Groundwater levels are falling in the remaining 30%, amounting to a net annual depletion of 8.0 +/- 3.0 km3. Within 60% of the aquifer, access to potable groundwater is restricted by excessive salinity or arsenic. Recent groundwater depletion in northern India and Pakistan has occurred within a longer history of groundwater accumulation from extensive canal leakage. This basin-wide synthesis of in situ groundwater observations provides the spatial detail essential for policy development, and the historical context to help evaluate recent satellite gravity data.

  17. In situ observations of waves in Venus’s polar lower thermosphere with Venus Express aerobraking

    NASA Astrophysics Data System (ADS)

    Müller-Wodarg, Ingo C. F.; Bruinsma, Sean; Marty, Jean-Charles; Svedhem, Håkan

    2016-08-01

    Waves are ubiquitous phenomena found in oceans and atmospheres alike. From the earliest formal studies of waves in the Earth’s atmosphere to more recent studies on other planets, waves have been shown to play a key role in shaping atmospheric bulk structure, dynamics and variability. Yet, waves are difficult to characterize as they ideally require in situ measurements of atmospheric properties that are difficult to obtain away from Earth. Thus, we have incomplete knowledge of atmospheric waves on planets other than our own, and we are thereby limited in our ability to understand and predict planetary atmospheres. Here we report the first ever in situ observations of atmospheric waves in Venus’s thermosphere (130-140 km) at high latitudes (71.5°-79.0°). These measurements were made by the Venus Express Atmospheric Drag Experiment (VExADE) during aerobraking from 24 June to 11 July 2014. As the spacecraft flew through Venus’s atmosphere, deceleration by atmospheric drag was sufficient to obtain from accelerometer readings a total of 18 vertical density profiles. We infer an average temperature of T = 114 +/- 23 K and find horizontal wave-like density perturbations and mean temperatures being modulated at a quasi-5-day period.

  18. Are Global In-Situ Ocean Observations Fit-for-purpose? Applying the Framework for Ocean Observing in the Atlantic.

    NASA Astrophysics Data System (ADS)

    Visbeck, M.; Fischer, A. S.; Le Traon, P. Y.; Mowlem, M. C.; Speich, S.; Larkin, K.

    2015-12-01

    There are an increasing number of global, regional and local processes that are in need of integrated ocean information. In the sciences ocean information is needed to support physical ocean and climate studies for example within the World Climate Research Programme and its CLIVAR project, biogeochemical issues as articulated by the GCP, IMBER and SOLAS projects of ICSU-SCOR and Future Earth. This knowledge gets assessed in the area of climate by the IPCC and biodiversity by the IPBES processes. The recently released first World Ocean Assessment focuses more on ecosystem services and there is an expectation that the Sustainable Development Goals and in particular Goal 14 on the Ocean and Seas will generate new demands for integrated ocean observing from Climate to Fish and from Ocean Resources to Safe Navigation and on a healthy, productive and enjoyable ocean in more general terms. In recognition of those increasing needs for integrated ocean information we have recently launched the Horizon 2020 AtlantOS project to promote the transition from a loosely-coordinated set of existing ocean observing activities to a more integrated, more efficient, more sustainable and fit-for-purpose Atlantic Ocean Observing System. AtlantOS takes advantage of the Framework for Ocean observing that provided strategic guidance for the design of the project and its outcome. AtlantOS will advance the requirements and systems design, improving the readiness of observing networks and data systems, and engaging stakeholders around the Atlantic. AtlantOS will bring Atlantic nations together to strengthen their complementary contributions to and benefits from the internationally coordinated Global Ocean Observing System (GOOS) and the Blue Planet Initiative of the Global Earth Observation System of Systems (GEOSS). AtlantOS will fill gaps of the in-situ observing system networks and will ensure that their data are readily accessible and useable. AtlantOS will demonstrate the utility of

  19. In Situ Observation of MgO Inclusions in Liquid Iron-Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Mu, Haoyuan; Zhang, Tongsheng; Yang, Liang; Xavier, Rodrigo R.; Fruehan, Richard J.; Webler, Bryan A.

    2016-08-01

    This study showed that MgO inclusions can be stable in liquid iron with elevated Al and it illustrated an important role of vaporization in the evolution of inclusions. Previous studies have shown that dissolved Al reduces MgO from slags and refractories, leading to spinel (MgAl2O4) inclusions. The elevated Al content of newer steels raises the possibility that MgO inclusions can be stable. In this work, MgO inclusions were produced and observed in an Fe-Al alloy. The inclusions in the liquid alloy at 1873 K (1600 °C) were observed in situ with a Confocal Laser Scanning Microscope (CLSM). Two types of experiments were performed: one where only a metal sample was melted and the other where the sample was in contact with a liquid, MgO-saturated slag. When no slag was present, the MgO inclusions shrank and disappeared at 1873 K (1600 °C). No inclusions were observed in situ during cooling or in post-CLSM analysis. When the MgO-saturated slag was present, the inclusion sizes were essentially constant and MgO was observed on the surface of post-CLSM samples. Analysis of the results showed that MgO can be stable in 1873 K (1600 °C), but that its presence depends on the rate of removal of Mg due to vaporization and the supply of Mg due to slag/metal or refractory/metal reactions.

  20. In-situ observation of xenon nanocrystals in aluminum under electron and ion irradiation in transmission electron microscope.

    SciTech Connect

    Furuya, K.

    1998-11-11

    In-situ ion irradiation in the transmission electron microscope (TEM) is one of the unique techniques to investigate the structural evolution of materials induced by particle bombardments. In spite of many efforts to get clear results from in-situ ion irradiation, the results were sometimes unclear because of physical and technical problems associated with TEM and ion beam hardwares. This paper describes a newly developed ion beam interface with an ultra-high voltage TEM (HVTEM) for in-situ observation of ion implantation of metals and alloys in atomic scale.

  1. The Sodankylä in-situ soil moisture observation network: an example application to Earth Observation data product evaluation

    NASA Astrophysics Data System (ADS)

    Ikonen, J.; Vehviläinen, J.; Rautiainen, K.; Smolander, T.; Lemmetyinen, J.; Bircher, S.; Pulliainen, J.

    2015-12-01

    Soil moisture is one of the main drivers in water, energy, and carbon cycles. Both latent and sensible heat fluxes, governing the air temperature and humidity boundary layer over land, are affected by variations in soil moisture. During the last decade there has been considerable development in remote sensing techniques relating to soil moisture retrievals over large areas. Within the framework of the European Space Agency's (ESA) Climate Change Initiative (CCI) a new soil moisture product has been generated, merging different satellite-based surface soil moisture based products. Such remotely sensed data needs to be validated by means of in-situ observations in different climatic regions. In that context, a comprehensive, distributed network of in-situ measurement stations gathering information on soil moisture, as well as soil temperature, has been set up in recent years at the Finnish Meteorological Institute's (FMI) Sodankylä Arctic research station. The network forms a (CAL-VAL) reference site and is used as a tool to evaluate the validity of satellite retrievals of soil properties. In this paper we present the Sodankylä CAL-VAL reference site soil moisture observation network. The procedures for choosing the representative sites for individual soil moisture network stations are discussed, as well as the development of a weighted average of top layer (5-10 cm) soil moisture over the study area. Comparisons of top layer soil moisture around the Sodankylä CAL-VAL site between the years 2012 and 2014 using ESA CCI soil moisture data against in-situ network observations were conducted. The comparisons were made against a single CCI data product pixel encapsulating the Sodankylä observation sites. Comparisons have been made against both daily CCI soil moisture estimates and against weekly running average values. Soil moisture comparisons are only conducted during snow free and thawed periods, as the presence of snow and soil frost interfere with Earth

  2. Extrapolation of in situ data from 1-km squares to adjacent squares using remote sensed imagery and airborne lidar data for the assessment of habitat diversity and extent.

    PubMed

    Lang, M; Vain, A; Bunce, R G H; Jongman, R H G; Raet, J; Sepp, K; Kuusemets, V; Kikas, T; Liba, N

    2015-03-01

    Habitat surveillance and subsequent monitoring at a national level is usually carried out by recording data from in situ sample sites located according to predefined strata. This paper describes the application of remote sensing to the extension of such field data recorded in 1-km squares to adjacent squares, in order to increase sample number without further field visits. Habitats were mapped in eight central squares in northeast Estonia in 2010 using a standardized recording procedure. Around one of the squares, a special study site was established which consisted of the central square and eight surrounding squares. A Landsat-7 Enhanced Thematic Mapper Plus (ETM+) image was used for correlation with in situ data. An airborne light detection and ranging (lidar) vegetation height map was also included in the classification. A series of tests were carried out by including the lidar data and contrasting analytical techniques, which are described in detail in the paper. Training accuracy in the central square varied from 75 to 100 %. In the extrapolation procedure to the surrounding squares, accuracy varied from 53.1 to 63.1 %, which improved by 10 % with the inclusion of lidar data. The reasons for this relatively low classification accuracy were mainly inherent variability in the spectral signatures of habitats but also differences between the dates of imagery acquisition and field sampling. Improvements could therefore be made by better synchronization of the field survey and image acquisition as well as by dividing general habitat categories (GHCs) into units which are more likely to have similar spectral signatures. However, the increase in the number of sample kilometre squares compensates for the loss of accuracy in the measurements of individual squares. The methodology can be applied in other studies as the procedures used are readily available. PMID:25648761

  3. In-situ turbulence observations in the stratospheric wind and temperature field with LITOS

    NASA Astrophysics Data System (ADS)

    Schneider, A.; Theuerkauf, A.; Gerding, M.; Lübken, F.-J.

    2012-04-01

    Although stably stratified, turbulence occurs in the stratosphere due to breaking gravity waves. This leads to energy dissipation which modifies the energy transfer from the troposphere to the mesosphere. Stratospheric turbulence is also important for vertical mixing of trace species. In order to derive turbulent parameters accurately very small scales on the order of centimeters and below have to be resolved. This can only be performed applying in-situ techniques. Our balloon-borne in-situ measurement system LITOS (Leibniz Institute Turbulence Observations in the Stratosphere) utilizes constant temperature anemometer (CTA) and constant current anemometer (CCA) for simultaneous observation of small scale fluctuations of wind and temperature with high vertical resolution (~1 mm). The CTA consists of a small, thin (5 µm) wire kept at constant temperature; its principle of operation is based on the cooling effect of the air flow around the wire. The CCA is a thin (3.8 µm) wire which is basically operated as a resistance thermometer. Three flights in different configurations have been carried out at Kiruna, Sweden (67°N, 21°E) within the BEXUS programme in 2008, 2009 and 2011. The balloons reached altitudes of typically 27 km. To our knowledge, during the flights in 2009 and 2011 the first simultaneous turbulence measurements of winds and temperatures in the stratosphere were performed. Turbulent layers with a vertical thickness in the order of several 10 m have been observed. Results for energy dissipation rates computed directly from the spectrum of wind or temperature fluctuations will be presented. We will compare measurements from different flights for both wind and temperature fluctuations and consider a potential dependence on background conditions.

  4. Comparison of optical and microphysical properties of pure Saharan mineral dust observed with AERONET Sun photometer, Raman lidar, and in situ instruments during SAMUM 2006

    NASA Astrophysics Data System (ADS)

    Müller, D.; Lee, K.-H.; Gasteiger, J.; Tesche, M.; Weinzierl, B.; Kandler, K.; Müller, T.; Toledano, C.; Otto, S.; Althausen, D.; Ansmann, A.

    2012-04-01

    The Saharan Mineral Dust Experiment (SAMUM) 2006, Morocco, aimed at the characterization of optical, physical, and radiative properties of Saharan dust. AERONET Sun photometer, several lidars (Raman and high-spectral-resolution instruments), and airborne and ground-based in situ instruments provided us with a comprehensive set of data on particle-shape dependent and particle-shape independent dust properties. We compare 4 measurement days in detail, and we carry out a statistical analysis for some of the inferred data products for the complete measurement period. Particle size distributions and complex refractive indices inferred from the Sun photometer observations and measured in situ aboard a research aircraft show systematic differences. We find differences in the wavelength-dependence of single-scattering albedo, compared to light-scattering computations that use data from SOAP (spectral optical absorption photometer). AERONET data products of particle size distribution, complex refractive index, and axis ratios were used to compute particle extinction-to-backscatter (lidar) ratios and linear particle depolarization ratios. We find differences for these parameters to lidar measurements of lidar ratio and particle depolarization ratio. Differences particularly exist at 355 nm, which may be the result of differences of the wavelength-dependent complex refractive index that is inferred by the methods employed in this field campaign. We discuss various error sources that may lead to the observed differences.

  5. Concurrent remote and in situ wave and current observations at a tidal inlet

    NASA Astrophysics Data System (ADS)

    Honegger, D. A.; Haller, M. C.; Lerczak, J. A.; McEnaney, P.

    2010-12-01

    Strong tidal currents can have a dominant influence on the incident wave field at tidal inlets such as Yaquina Bay in Oregon. Swift ebb currents, horizontal shear in the ebb jet, as well as complex bathymetry can affect the location, direction and severity of wave breaking along navigation routes. In combination with rapidly changing wave conditions, this wave breaking hazard can prove fatal for vessels entering or leaving harbors. However, efforts to model where these waves break remain challenging. This work gathers a comprehensive and concurrent set of field observations to capture wave and current conditions for future wave-current interaction model validation. The observations include remote and in situ measurements of the tidal currents and incident wave fields, as well as currents and waves directly offshore of the jetty entrance. Inter-jetty surface current measurements were gathered through the novel use of the RiverSonde (CODAR Ocean Sensors) UHF radar system. In addition, observations of the vertical structure of the currents were gathered with a nearby AWAC (Nortek) and ADCP. Directional wave spectra were collected by a WaveRider buoy that we deployed 5 km offshore along the 50 m isobaths. Finally, the Newport site is also the home of a long-term marine radar wave observing system, which is a node on the NANOOS observing system. Remote sensing observations of the breaking wave field from this system will be coupled with the in-situ observations and RiverSonde data in order to present a synoptic picture of wave-current interaction processes at this inlet. The overall goal of this work is to develop and validate a wave modeling system for this site that includes the effects of wave-current interaction. We are using the Unstructured-grid Simulating Waves Nearshore (UnSWAN) wave model covering the Newport coastal region. In addition, our collaborators are applying the Finite Volume Coastal Ocean Model (FVCOM) to Yaquina Bay and vicinity. We seek to combine

  6. Decorrelation analysis of L-band interferometry over the Piton de la Fournaise volcano (France) using airborne LiDAR data and in situ measurements

    NASA Astrophysics Data System (ADS)

    Sedze, M.; Bretar, F.; Heggy, E.; Berveiller, D.; Jacquemoud, S.

    2012-12-01

    We combine ALOS-PALSAR coherence images with airborne LiDAR data, both acquired over the Piton de la Fournaise volcano (Reunion Island, France) in 2008 and 2009, to determine the cause of errors that affects repeat-pass InSAR measurements. We investigate how phase coherence varies with the nature of volcanic terrains and vegetation density in a typical volcanic environment. Our study is focused on several sites characterized by different vegetation densities (Leaf Area Index or LAI) and on bare volcanic surfaces displaying different geophysical properties: pahoehoe and a'a lava flows, slabby pahoehoe flows, and pyroclastic deposits (lapillis). The high resolution DTM generated using LiDAR data is used to subtract out the topographic contribution from the interferogram and to improve the radar coherence maps. To evaluate the coherence loss terms, the relationship between LiDAR intensity and radar coherence is then analyzed over several surfaces. Pyroclastic deposits and a'a lava flows are characterized by low coherence and intensity values, with high coherence standard deviations; pahoehoe and slabby lava flows display high coherence and intensity values, with low standard deviations; coherence decreases in regions covered with dense vegetation, whereas LiDAR intensity increases, and we observe a higher dispersion of coherence and intensity values depending on the type and density of plants. Additionally, a geological survey has been conducted in October 2011 to measure the physical properties of the surface and better interpret the radar images. From digital photographs, we first computed ~ 25 m^2 DTM at 1 mm spatial resolution using an automatic image matching method. Several 4 m long linear profiles have been extracted to calculate three roughness parameters: the standard deviation of height σ, the correlation length L_c, and the Z_s parameter defined as Z_s= σ^2/L_c. They describe soil surface microrelief: the rougher the surface, the lower the correlation

  7. IBEX: The Evolving Global View and Synergies with In Situ Voyager Observations

    NASA Astrophysics Data System (ADS)

    McComas, D. J.

    2015-12-01

    The Interstellar Boundary Explorer (IBEX) has now returned nearly seven years of observations, which comprise 14 full sets of energy resolved all-sky maps and provide the global view of our Sun's interaction with very local part of the galaxy. With such a long baseline of observations, we are able to examine time variations in the outer heliosphere as it responds to both 11-year solar cycle variations and longer term secular evolution of the three dimensional solar wind. Now that we have collected over half a solar cycle of observations, IBEX is beginning to show us how the heliosphere - our home in the galaxy - varies in time as well as space. In this talk we present the most recent observations and review some other recent discoveries from IBEX. We also examine the synergy between the global view provided by IBEX and the in situ observations form the Voyager 1 and 2 spacecraft. Finally, we discuss the incredible improvement in interstellar observations - and our understanding of the local interstellar medium - that the Interstellar Mapping and Acceleration Probe (IMAP) will provide.

  8. In situ observations of austenite grain growth in Fe-C-Mn-Si super bainitic steel

    NASA Astrophysics Data System (ADS)

    Liu, Feng; Xu, Guang; Zhang, Yu-long; Hu, Hai-jiang; Zhou, Lin-xin; Xue, Zheng-liang

    2013-11-01

    In situ observations of austenite grain growth in Fe-C-Mn-Si super bainitic steel were conducted on a high-temperature laser scanning confocal microscope during continuous heating and subsequent isothermal holding at 850, 1000, and 1100°C for 30 min. A grain growth model was proposed based on experimental results. It is indicated that the austenite grain size increases with austenitizing temperature and holding time. When the austenitizing temperature is above 1100°C, the austenite grains grow rapidly, and abnormal austenite grains occur. In addition, the effect of heating rate on austenite grain growth was investigated, and the relation between austenite grains and bainite morphology after bainitic transformations was also discussed.

  9. Direct observation of catalytic oxidation of particulate matter using in situ TEM.

    PubMed

    Kamatani, Kohei; Higuchi, Kimitaka; Yamamoto, Yuta; Arai, Shigeo; Tanaka, Nobuo; Ogura, Masaru

    2015-07-08

    The ability to observe chemical reactions at the molecular level convincingly demonstrates the physical and chemical phenomena occurring throughout a reaction mechanism. Videos obtained through in situ transmission electron microscopy (TEM) revealed the oxidation of catalytic soot under practical reaction conditions. Carbon oxidation reactions using Ag/SiO2 or Cs2CO3/nepheline catalysts were performed at 330 °C under an O2 flow of 0.5 Pa in the TEM measurement chamber. Ag/SiO2 catalyzed the reaction at the interface of the mobile Ag species and carbon, while the Cs species was fixed on the nepheline surface during the reaction. In the latter case, carbon particles moved, remained attached to the Cs2CO3/nepheline surface, and were consumed at the interface by the oxidation reaction. Using this technique, we were able to visualize such mobile and immobile catalysis according to different mechanisms.

  10. In-Situ Observation of Membrane Protein Folding during Cell-Free Expression

    PubMed Central

    Fitter, Jörg; Büldt, Georg; Heberle, Joachim; Schlesinger, Ramona; Ataka, Kenichi

    2016-01-01

    Proper insertion, folding and assembly of functional proteins in biological membranes are key processes to warrant activity of a living cell. Here, we present a novel approach to trace folding and insertion of a nascent membrane protein leaving the ribosome and penetrating the bilayer. Surface Enhanced IR Absorption Spectroscopy selectively monitored insertion and folding of membrane proteins during cell-free expression in a label-free and non-invasive manner. Protein synthesis was performed in an optical cell containing a prism covered with a thin gold film with nanodiscs on top, providing an artificial lipid bilayer for folding. In a pilot experiment, the folding pathway of bacteriorhodopsin via various secondary and tertiary structures was visualized. Thus, a methodology is established with which the folding reaction of other more complex membrane proteins can be observed during protein biosynthesis (in situ and in operando) at molecular resolution. PMID:26978519

  11. In situ observations of catalyst dynamics during surface-bound carbon nanotube nucleation.

    PubMed

    Hofmann, Stephan; Sharma, Renu; Ducati, Caterina; Du, Gaohui; Mattevi, Cecilia; Cepek, Cinzia; Cantoro, Mirco; Pisana, Simone; Parvez, Atlus; Cervantes-Sodi, Felipe; Ferrari, Andrea C; Dunin-Borkowski, Rafal; Lizzit, Silvano; Petaccia, Luca; Goldoni, Andrea; Robertson, John

    2007-03-01

    We present atomic-scale, video-rate environmental transmission electron microscopy and in situ time-resolved X-ray photoelectron spectroscopy of surface-bound catalytic chemical vapor deposition of single-walled carbon nanotubes and nanofibers. We observe that transition metal catalyst nanoparticles on SiOx support show crystalline lattice fringe contrast and high deformability before and during nanotube formation. A single-walled carbon nanotube nucleates by lift-off of a carbon cap. Cap stabilization and nanotube growth involve the dynamic reshaping of the catalyst nanocrystal itself. For a carbon nanofiber, the graphene layer stacking is determined by the successive elongation and contraction of the catalyst nanoparticle at its tip.

  12. Direct observation of catalytic oxidation of particulate matter using in situ TEM

    PubMed Central

    Kamatani, Kohei; Higuchi, Kimitaka; Yamamoto, Yuta; Arai, Shigeo; Tanaka, Nobuo; Ogura, Masaru

    2015-01-01

    The ability to observe chemical reactions at the molecular level convincingly demonstrates the physical and chemical phenomena occurring throughout a reaction mechanism. Videos obtained through in situ transmission electron microscopy (TEM) revealed the oxidation of catalytic soot under practical reaction conditions. Carbon oxidation reactions using Ag/SiO2 or Cs2CO3/nepheline catalysts were performed at 330 °C under an O2 flow of 0.5 Pa in the TEM measurement chamber. Ag/SiO2 catalyzed the reaction at the interface of the mobile Ag species and carbon, while the Cs species was fixed on the nepheline surface during the reaction. In the latter case, carbon particles moved, remained attached to the Cs2CO3/nepheline surface, and were consumed at the interface by the oxidation reaction. Using this technique, we were able to visualize such mobile and immobile catalysis according to different mechanisms. PMID:26154580

  13. Deep-sea macrourid fishes scavenge on plant material: Evidence from in situ observations

    NASA Astrophysics Data System (ADS)

    Jeffreys, Rachel M.; Lavaleye, Marc S. S.; Bergman, Magda J. N.; Duineveld, Gerard C. A.; Witbaard, Rob; Linley, Thom

    2010-04-01

    Deep-sea benthic communities primarily rely on an allochthonous food source. This may be in the form of phytodetritus or as food falls e.g. sinking carcasses of nekton or debris of marine macrophyte algae. Deep-sea macrourids are the most abundant demersal fish in the deep ocean. Macrourids are generally considered to be the apex predators/scavengers in deep-sea communities. Baited camera experiments and stable isotope analyses have demonstrated that animal carrion derived from the surface waters is an important component in the diets of macrourids; some macrourid stomachs also contained vegetable/plant material e.g. onion peels, oranges, algae. The latter observations led us to the question: is plant material an attractive food source for deep-sea scavenging fish? We simulated a plant food fall using in situ benthic lander systems equipped with a baited time-lapse camera. Abyssal macrourids and cusk-eels were attracted to the bait, both feeding vigorously on the bait, and the majority of the bait was consumed in <30 h. These observations indicate (1) plant material can produce an odour plume similar to that of animal carrion and attracts deep-sea fish, and (2) deep-sea fish readily eat plant material. This represents to our knowledge the first in situ documentation of deep-sea fish ingesting plant material and highlights the variability in the scavenging nature of deep-sea fishes. This may have implications for food webs in areas where macrophyte/seagrass detritus is abundant at the seafloor e.g. canyon systems and continental shelves close to seagrass meadows (Bahamas and Mediterranean).

  14. In-situ observation of irradiation quantities using a tethered balloon

    NASA Astrophysics Data System (ADS)

    Becker, Ralf; Gross, Steffen; Behrens, Klaus

    2014-05-01

    Irradiance is a key parameter in Earth's weather and climate system. Accurate observations of the components of the radiation budget are therefore essential to create reliable time series, to analyse spatial variability and to test, validate and adapt satellite-based algorithms. This holds true for near surface measurements as well as for in-situ observations in the lower troposphere. Such measurements are difficult to realise and therefore rarely performed. A tethered balloon system manufactured by Vailsala (9 cbm) is utilised as a carrier of a radiation budget sonde operating up to 1000 m above ground. Application is limited to fair weather conditions with maximum winds of 20 km/h and visibility greater than 3 km at ground level. The experimental setup is composed of a downward and upward looking pair of Kipp&Zonen CM11 (0.305-2.8 μm) and a corresponding pair of Kipp&Zonen CG4 (4.5 - 42 μm). Instruments are categorized as WMO 'secondary standard' according to ISO9660 and can be characterised as sufficiently robust and with acceptable response time for this purpose. Instrumentation is complemented by meteorological sensors (wind, temperature, humidity) flown on a dedicated suspension close (less than 50 m distance) to radiation sonde. In-situ measurements of irradiation in flowing and turbulent air are subjected to errors due to moving platform (roll/yaw/pitch). Potential deviations to near-surface measurements are discussed and an error estimate is given. Some comparisons of results of radiative transfer calculations for simple meteorological conditions have been made so far. It can be accomplished either by referring to profiles or by evaluating time series taken at elevated levels. Profiling lacks stationarity most time of a day due to high variability of shortwave downward and thus must be interpreted carefully. First results for longwave profiles as well as evaluation of time series obtained at distinct levels above ground show good correspondence.

  15. Airborne lidar observations of volcanic ash during the eruption of Eyjafjallajökull in Spring 2010

    NASA Astrophysics Data System (ADS)

    Marenco, F.; Johnson, B.; Turnbull, K.; Haywood, J.; Newman, S.; Webster, H.; Cooke, M.; Dorsey, J.; Ricketts, H.; Clarisse, L.

    2012-04-01

    The London Volcanic Ash Advisory Centre (VAAC), based at the Met Office, provided forecast guidance for the Civil Aviation Authority during the eruption of Eyjafjallajökull in April-May 2010. Besides providing daily forecasts using the Numerical Atmospheric-dispersion Modelling Environment (NAME), a series of observational activities were carried out by the Met Office, involving ground-based lidars, the exploitation of satellite data, and research flights using the Facility for Airborne Atmospheric Measurements BAe-146 research aircraft (FAAM, www.faam.ac.uk), on which this talk is focused. Due to safety restrictions, aircraft sampling has only been performed in areas where ash concentrations where forecasted to be less than 2000 μg/m3. Volcanic ash layers were observed using an elastic backscatter lidar on-board the FAAM aircraft operating at 355 nm, which allowed detailed mapping of the plumes. A flight on 4 May overpassed the ground-based lidar in Aberystwyth a few times. This provided ground truth validation of the on-board lidar and of its data inversion procedure. The ash layer during this flight was found to be in patches of short horizontal extent, but despite the strong horizontal inhomogeneity the two lidars showed excellent qualitative and quantitative agreement. Moreover, radiative transfer computations using the lidar-derived profiles of aerosol extinction led to a good reconstruction of observed radiance spectra with on-board spectrometers. Aircraft in situ measurements of the particle size-distribution permitted the evaluation of a coarse extinction fraction (ranging 0.5-1) and a coarse mode specific extinction (0.6-0.9 m2/g) for six research flights. These quantities were then used to convert the lidar-derived aerosol extinction to ash concentration (with an estimated uncertainty of a factor of two). The combination of lidar and in-situ sampling of aerosol properties has thus offered us the opportunity to compile a dataset of the airborne

  16. Airborne in-situ investigations of the Eyjafjallajökull volcanic ash plume on Iceland and over north-western Germany with light aircrafts and optical particle counters

    NASA Astrophysics Data System (ADS)

    Weber, K.; Eliasson, J.; Vogel, A.; Fischer, C.; Pohl, T.; van Haren, G.; Meier, M.; Grobéty, B.; Dahmann, D.

    2012-03-01

    During the time period of the eruption of the Icelandic volcano Eyjafjallajökull in April/May 2010 the Duesseldorf University of Applied Sciences has performed 14 research flights in situations with and without the volcanic ash plume over Germany. In parallel to the research flights in Germany three measurement flights have been performed by the University of Iceland in May 2010 over the western part of Iceland. During two of these flights the outskirts of the eruption plume were entered directly, delivering most direct measurements within the eruption plume during this eruptive event. For all the measurement flights reported here, light durable piston-motor driven aircrafts were used, which were equipped with optical particle counters for in-situ measurements. Real-time monitoring of the particle concentrations was possible during the flights. As different types of optical particle counters have been used in Iceland and Germany, the optical particle counters have been re-calibrated after the flights to the same standard using gravimetric reference methods and original Eyjafjallajökull volcanic ash samples. In-situ measurement results with high spatial resolution, directly from the eruption plume in Iceland as well as from the dispersed and several days old plume over Germany, are therefore presented here for the first time. They are normalized to the same ash concentration calibration standard. Moreover, airborne particles could be sampled directly out of the eruption plume in Iceland as well as during the flights over Germany. During the research flights over Iceland from 9 May 2011 to 11 May 2011 the ash emitted from the vent of the volcano turned out to be concentrated in a narrow well-defined plume of about 10 km width at a distance of 45-60 km away from the vent. Outside this plume the airborne ash concentrations could be proved to be below 50 μg m -3 over western Iceland. However, by entering the outskirts of the plume directly the research aircraft could

  17. On the rates of coronal mass ejections: remote solar and in situ observations

    NASA Astrophysics Data System (ADS)

    Riley, P.; Cane, H.; Richardson, I. G.; Gopalswamy, N.; Linker, J. A.; Mikic, Z.; Lionello, R.

    2006-05-01

    In this study we compare the rates of coronal mass ejections (CMEs) as inferred from remote solar observations and interplanetary CMEs (ICMEs) as inferred from in situ observations at both 1 AU and Ulysses for almost an entire solar cycle (1996 through 2004). We find that, while the rates of CMEs and ICMEs track each other well at solar minimum, they diverge significantly in early 1998, during the ascending phase of the solar cycle, with the remote solar observations yielding approximately 20 times more events than are seen in situ at 1 AU. This divergence persists through 2004. We discuss several possible causes, including: (1) the appearance of mid-latitude active regions; (2) the increased rate of high-latitude CMEs; and (3) the strength of the global solar field. We conclude that the most likely interpretation is that this divergence is due to the birth of mid-latitude active regions, which are the sites of a distinct population of CMEs that are only partially intercepted by Earth. This conclusion is supported by the following points: (1) A similar divergence occurs between ICMEs in which magnetic clouds are observed (MCs), and those that are not; and (2) a number of pronounced enhancements in the CME rate, separated by approximately one year, are also mirrored and in ICME rate, but not obviously in the MC rate. We provide a simple geometric argument that shows that the computed CME and ICME rates are consistent with each other. The origins of the individual peaks can be traced back to unusually strong active regions on the Sun. Taken together, these results suggest that whether one observes a flux rope within an ICME is sensitive to the trajectory of the spacecraft through the ICME, i.e., an observational selection effect. This conclusion is supported by models of CME eruption and evolution, which: (1) are incapable of producing a CME that does not contain an embedded flux rope; and (2) demonstrate that glancing intercepts can produce ICME-like signatures

  18. Comparisons of cirrus cloud properties between polluted and pristine air based on in-situ observations from the NSF HIPPO, EU INCA and NASA ATTREX campaigns

    NASA Astrophysics Data System (ADS)

    Diao, M.; Schumann, U.; Jensen, J. B.; Minikin, A.

    2015-12-01

    The radiative forcing of cirrus clouds is influenced by microphysical (e.g., ice crystal number concentration and size distribution) and macroscopic properties. Currently it is still unclear how the formation of cirrus clouds and their microphysical properties are influenced by anthropogenic emissions. In this work, we use airborne in-situ observations to compare cirrus cloud properties between polluted and pristine regions. Our dataset includes: the NSF HIAPER Pole-to-Pole Observations (HIPPO) Global campaign (2009-2011), the EU Interhemispheric Differences In Cirrus Properties from Anthropogenic Emissions (INCA) campaign (2000) and the NASA Airborne Tropical Tropopause Experiment (ATTREX) campaign (2014). The combined dataset include observations of both extratropical (HIPPO and INCA) and tropical (ATTREX) cirrus, over the Northern and Southern Hemispheres. We use the in-situ measured carbon monoxide (CO) mixing ratio as a pollution indicator, and compare ice microphysical properties (i.e., ice crystal number concentration (Nc) and number-weighted mean diameter (Dc)) between air masses with higher and lower CO. All analyses are restricted to T ≤ -40°C. By analyzing ice crystals (Fast-2DC, 87.5-1600 µm) in HIPPO, we found that Dc decreases with increasing CO concentration at multiple constant pressure levels. In addition, analysis of INCA data shows that Nc and extinction of small ice particles (FSSP 3-20 µm) increases with increasing CO. Particles < 87.5 µm in Fast-2DC data are not considered due to uncertainty in sample volume, and the FSSP measurements are subject to possible shattering. We further analyze the ice crystals (SPEC FCDP, 1-50 µm) in the tropical tropopause layer in ATTREX. At -70°C to -90°C, we found that the average Nc (Dc) increases (decreases) at higher CO. Overall, our results suggest that extratropical and tropical cirrus are likely to have more numerous small ice particles, when sampled in the more polluted background. Back

  19. In situ observation of a hydrogel-glass interface during sliding friction.

    PubMed

    Yamamoto, Tetsurou; Kurokawa, Takayuki; Ahmed, Jamil; Kamita, Gen; Yashima, Shintaro; Furukawa, Yuichiro; Ota, Yuko; Furukawa, Hidemitsu; Gong, Jian Ping

    2014-08-14

    Direct observation of hydrogel contact with a solid surface in water is indispensable for understanding the friction, lubrication, and adhesion of hydrogels under water. However, this is a difficult task since the refractive index of hydrogels is very close to that of water. In this paper, we present a novel method to in situ observe the macroscopic contact of hydrogels with a solid surface based on the principle of critical refraction. This method was applied to investigate the sliding friction of a polyacrylamide (PAAm) hydrogel with glass by using a strain-controlled parallel-plate rheometer. The study revealed that when the compressive pressure is not very high, the hydrogel forms a heterogeneous contact with the glass, and a macro-scale water drop is trapped at the soft interface. The pre-trapped water spreads over the interface to decrease the contact area with the increase in sliding velocity, which dramatically reduces the friction of the hydrogel. The study also revealed that this heterogeneous contact is the reason for the poor reproducibility of hydrogel friction that has been often observed in previous studies. Under the condition of homogeneous full contact, the molecular origin of hydrogel friction in water is discussed. This study highlights the importance of direct interfacial observation to reveal the friction mechanism of hydrogels.

  20. High-resolution in situ observations of electron precipitation-causing EMIC waves

    DOE PAGES

    Rodger, Craig J.; Hendry, Aaron T.; Clilverd, Mark A.; Kletzing, Craig A.; Brundell, James B.; Reeves, Geoffrey D.

    2015-11-21

    Electromagnetic ion cyclotron (EMIC) waves are thought to be important drivers of energetic electron losses from the outer radiation belt through precipitation into the atmosphere. While the theoretical possibility of pitch angle scattering-driven losses from these waves has been recognized for more than four decades, there have been limited experimental precipitation observations to support this concept. We have combined satellite-based observations of the characteristics of EMIC waves, with satellite and ground-based observations of the EMIC-induced electron precipitation. In a detailed case study, supplemented by an additional four examples, we are able to constrain for the first time the location, size,more » and energy range of EMIC-induced electron precipitation inferred from coincident precipitation data and relate them to the EMIC wave frequency, wave power, and ion band of the wave as measured in situ by the Van Allen Probes. As a result, these observations will better constrain modeling into the importance of EMIC wave-particle interactions.« less

  1. High-resolution in situ observations of electron precipitation-causing EMIC waves

    SciTech Connect

    Rodger, Craig J.; Hendry, Aaron T.; Clilverd, Mark A.; Kletzing, Craig A.; Brundell, James B.; Reeves, Geoffrey D.

    2015-11-21

    Electromagnetic ion cyclotron (EMIC) waves are thought to be important drivers of energetic electron losses from the outer radiation belt through precipitation into the atmosphere. While the theoretical possibility of pitch angle scattering-driven losses from these waves has been recognized for more than four decades, there have been limited experimental precipitation observations to support this concept. We have combined satellite-based observations of the characteristics of EMIC waves, with satellite and ground-based observations of the EMIC-induced electron precipitation. In a detailed case study, supplemented by an additional four examples, we are able to constrain for the first time the location, size, and energy range of EMIC-induced electron precipitation inferred from coincident precipitation data and relate them to the EMIC wave frequency, wave power, and ion band of the wave as measured in situ by the Van Allen Probes. As a result, these observations will better constrain modeling into the importance of EMIC wave-particle interactions.

  2. Airborne Science Program: Observing Platforms for Earth Science Investigations

    NASA Technical Reports Server (NTRS)

    Mace, Thomas H.

    2009-01-01

    This slide presentation reviews the Airborne Science Program and the platforms used for conducting investigations for the Earth System Science. Included is a chart that shows some of the aircraft and the operational altitude and the endurance of the aircraft, views of the Dryden Aircraft Operation Facility, and some of the current aircraft that the facility operates, and the varieties of missions that are flown and the type of instrumentation. Also included is a chart showing the attributes of the various aircraft (i.e., duration, weight for a payload, maximum altitude, airspeed and range) for comparison

  3. Assessment of a multi-species in situ FTIR for precise atmospheric greenhouse gas observations

    NASA Astrophysics Data System (ADS)

    Hammer, S.; Griffith, D. W. T.; Konrad, G.; Vardag, S.; Caldow, C.; Levin, I.

    2013-05-01

    We thoroughly evaluate the performance of a multi-species, in situ Fourier transform infrared (FTIR) analyser with respect to high-accuracy needs for greenhouse gas monitoring networks. The in situ FTIR analyser is shown to measure CO2, CO, CH4 and N2O mole fractions continuously, all with better reproducibility than the inter-laboratory compatibility (ILC) goals, requested by the World Meteorological Organization (WMO) for the Global Atmosphere Watch (GAW) programme. Simultaneously determined δ13CO2 reaches reproducibility as good as 0.03‰. Second-order dependencies between the measured components and the thermodynamic properties of the sample, (temperature, pressure and flow rate) and the cross sensitivities among the sample constituents are investigated and quantified. We describe an improved sample delivery and control system that minimises the pressure and flow rate variations, making post-processing corrections for those quantities non-essential. Temperature disequilibrium effects resulting from the evacuation of the sample cell are quantified and improved by the usage of a faster temperature sensor. The instrument has proven to be linear for all measured components in the ambient concentration range. The temporal stability of the instrument is characterised on different time scales. Instrument drifts on a weekly time scale are only observed for CH4 (0.04 nmol mol-1 day-1) and δ13CO2 (0.02‰ day-1). Based on 10 months of continuously collected quality control measures, the long-term reproducibility of the instrument is estimated to ±0.016 μmol mol-1 CO2, ±0.03‰ δ13CO2, ±0.14 nmol mol-1 CH4, ±0.1 nmol mol-1 CO and ±0.04 nmol mol-1 N2O. We propose a calibration and quality control scheme with weekly calibrations of the instrument that is sufficient to reach WMO-GAW inter-laboratory compatibility goals.

  4. Fabrication and In Situ Testing of Scalable Nitrate-Selective Electrodes for Distributed Observations

    NASA Astrophysics Data System (ADS)

    Harmon, T. C.; Rat'ko, A.; Dietrich, H.; Park, Y.; Wijsboom, Y. H.; Bendikov, M.

    2008-12-01

    Inorganic nitrogen (nitrate (NO3-) and ammonium (NH+)) from chemical fertilizer and livestock waste is a major source of pollution in groundwater, surface water and the air. While some sources of these chemicals, such as waste lagoons, are well-defined, their application as fertilizer has the potential to create distributed or non-point source pollution problems. Scalable nitrate sensors (small and inexpensive) would enable us to better assess non-point source pollution processes in agronomic soils, groundwater and rivers subject to non-point source inputs. This work describes the fabrication and testing of inexpensive PVC-membrane- based ion selective electrodes (ISEs) for monitoring nitrate levels in soil water environments. ISE-based sensors have the advantages of being easy to fabricate and use, but suffer several shortcomings, including limited sensitivity, poor precision, and calibration drift. However, modern materials have begun to yield more robust ISE types in laboratory settings. This work emphasizes the in situ behavior of commercial and fabricated sensors in soils subject to irrigation with dairy manure water. Results are presented in the context of deployment techniques (in situ versus soil lysimeters), temperature compensation, and uncertainty analysis. Observed temporal responses of the nitrate sensors exhibited diurnal cycling with elevated nitrate levels at night and depressed levels during the day. Conventional samples collected via lysimeters validated this response. It is concluded that while modern ISEs are not yet ready for long-term, unattended deployment, short-term installations (on the order of 2 to 4 days) are viable and may provide valuable insights into nitrogen dynamics in complex soil systems.

  5. Intermittency of magnetic field turbulence: Astrophysical applications of in-situ observations

    NASA Astrophysics Data System (ADS)

    Zelenyi, Lev M.; Bykov, Andrei M.; Uvarov, Yury A.; Artemyev, Anton V.

    2015-08-01

    We briefly review some aspects of magnetic turbulence intermittency observed in space plasmas. Deviation of statistical characteristics of a system (e.g. its high statistical momenta) from the Gaussian can manifest itself as domination of rare large intensity peaks often associated with the intermittency in the system's dynamics. Thirty years ago, Zeldovich stressed the importance of the non-Gaussian appearance of the sharp values of vector and scalar physical parameters in random media as a factor of magnetic field amplification in cosmic structures. Magnetic turbulence is governing the behavior of collisionless plasmas in space and especially the physics of shocks and magnetic reconnections. Clear evidence of intermittent magnetic turbulence was found in recent in-situ spacecraft measurements of magnetic fields in the near-Earth and interplanetary plasma environments. We discuss the potentially promising approaches of incorporating the knowledge gained from spacecraft in-situ measurements into modern models describing plasma dynamics and radiation in various astrophysical systems. As an example, we discuss supernova remnants (SNRs) which are known to be the sources of energy, momentum, chemical elements, and high-energy cosmic rays (CRs) in galaxies. Supernova shocks accelerate charged particles to very high energies and may strongly amplify turbulent magnetic fields via instabilities driven by CRs. Relativistic electrons accelerated in SNRs radiate polarized synchrotron emission in a broad range of frequencies spanning from the radio to gamma-rays. We discuss the effects of intermittency of magnetic turbulence on the images of polarized synchrotron X-ray emission of young SNRs and emission spectra of pulsar wind nebula.

  6. Validation of two gridded soil moisture products over India with in-situ observations

    NASA Astrophysics Data System (ADS)

    Unnikrishnan, C. K.; George, John P.; Lodh, Abhishek; Maurya, Devesh Kumar; Mallick, Swapan; Rajagopal, E. N.; Mohandas, Saji

    2016-07-01

    Surface level soil moisture from two gridded datasets over India are evaluated in this study. The first one is the UK Met Office (UKMO) soil moisture analysis produced by a land data assimilation system based on Extended Kalman Filter method (EKF), which make use of satellite observation of Advanced Scatterometer (ASCAT) soil wetness index as well as the screen level meteorological observations. Second dataset is a satellite soil moisture product, produced by National Remote Sensing Centre (NRSC) using passive microwave Advanced Microwave Scanning Radiometer 2 measurements. In-situ observations of soil moisture from India Meteorological Department (IMD) are used for the validation of the gridded soil moisture products. The difference between these datasets over India is minimum in the non-monsoon months and over agricultural regions. It is seen that the NRSC data is slightly drier (0.05%) and UKMO soil moisture analysis is relatively wet during southwest monsoon season. Standard AMSR-2 satellite soil moisture product is used to compare the NRSC and UKMO products. The standard AMSR-2 and UKMO values are closer in monsoon season and AMSR-2 soil moisture is higher than UKMO in all seasons. NRSC and AMSR-2 showed a correlation of 0.83 (significant at 0.01 level). The probability distribution of IMD soil moisture observation peaks at 0.25 m3/m3, NRSC at 0.15 m3/m3, AMSR-2 at 0.25 m3/m3 and UKMO at 0.35 m3/m3 during June-September period. Validation results show UKMO analysis has better correlation with in-situ observations compared to the NRSC and AMSR-2 datasets. The seasonal variation in soil moisture is better represented in UKMO analysis. Underestimation of soil moisture during monsoon season over India in NRSC data suggests the necessity of incorporating the actual vegetation for a better soil moisture retrieval using passive microwave sensors. Both products have good agreement over bare soil, shrubs and grassland compared to needle leaf tree, broad leaf tree and

  7. Enabling in-situ observation of organic aerosol speciated composition: Advances in TAG instrumentation (Invited)

    NASA Astrophysics Data System (ADS)

    Goldstein, A. H.; Worton, D. R.; Zhao, Y.; Kreisberg, N. M.; Teng, A. P.; Hering, S. V.; Gorecki, T.; Ranjan, M.; Hennigan, C. J.; Lambe, A.; Nguyen, N.; Donahue, N. M.; Robinson, A. L.; Jayne, J. T.; Williams, B. J.; Worsnop, D. R.

    2009-12-01

    The complex chemical composition of atmospheric aerosols, particularly the organic carbon portion, presents unique measurement challenges. We developed the Thermal Desorption Aerosol Gas chromatograph (TAG) system for hourly in-situ speciation of a wide range of primary and secondary organic compounds in aerosols. This instrument combines an impactor particle collector with thermal desorption followed by gas chromatography and mass spectrometric detection to provide separation, identification, and quantification of organic constituents at the molecular level. Observed compounds include alkanes, aldehydes, ketones, PAHs, monocarboxylic acids, and many more. The hourly time resolution measurements provided by TAG capture dynamic and frequent changes in aerosol composition that would not be resolved using traditional filter collection. TAG measurements also provide a much larger data set, facilitating the use of statistical approaches such as positive matrix factorization to identify source categories and their contributions to the total observed aerosol. Because TAG identifies organic compounds at the molecular level, it can build on the extensive work obtained by traditional GC/MS analysis of filter samples on source emission profiles and secondary organic aerosol formation. We report here continued developments in the capabilities of our TAG system. Most recently, we have incorporated a two-dimensional chromatography (GC×GC) capability into TAG, and now have that instrument operating with a time of flight (TOF) MS detector. Two-dimensional chromatography provides two types of compound separation, most typically by volatility and polarity. It uses two columns with different stationary phases connected in series separated by a modulator. The modulator periodically traps analytes eluting from the first column, and injects fractions of this effluent onto the second column in the form of narrow pulses providing additional separation for co-eluting peaks. The approach

  8. In situ alkali-silica reaction observed by x-ray microscopy

    SciTech Connect

    Kurtis, K.E.; Monteiro, P.J.M.; Brown, J.T.; Meyer-Ilse, W.

    1997-04-01

    In concrete, alkali metal ions and hydroxyl ions contributed by the cement and reactive silicates present in aggregate can participate in a destructive alkali-silica reaction (ASR). This reaction of the alkalis with the silicates produces a gel that tends to imbibe water found in the concrete pores, leading to swelling of the gel and eventual cracking of the affected concrete member. Over 104 cases of alkali-aggregate reaction in dams and spillways have been reported around the world. At present, no method exists to arrest the expansive chemical reaction which generates significant distress in the affected structures. Most existing techniques available for the examination of concrete microstructure, including ASR products, demand that samples be dried and exposed to high pressure during the observation period. These sample preparation requirements present a major disadvantage for the study of alkali-silica reaction. Given the nature of the reaction and the affect of water on its products, it is likely that the removal of water will affect the morphology, creating artifacts in the sample. The purpose of this research is to observe and characterize the alkali-silica reaction, including each of the specific reactions identified previously, in situ without introducing sample artifacts. For observation of unconditioned samples, x-ray microscopy offers an opportunity for such an examination of the alkali-silica reaction. Currently, this investigation is focusing on the effect of calcium ions on the alkali-silica reaction.

  9. Comprehensive ground-based and in situ observations of substorm expansion phase onset

    NASA Astrophysics Data System (ADS)

    Walsh, A. P.; Rae, J.; Fazakerley, A. N.; Murphy, K. R.; Mann, I. R.; Watt, C. E.; Volwerk, M.; Forsyth, C.; Singer, H. J.; Donovan, E. F.; Zhang, T.

    2010-12-01

    We present comprehensive ground-based and space-based in situ geosynchronous observations of a substorm expansion phase onset on 1 October 2005. The Double Star TC2 and GOES12 spacecraft were both located within the substorm current wedge during the substorm expansion phase onset, which occurred over the Canadian sector. We find that an onset of ULF waves in space was observed after onset on the ground by extending the AWESOME timing algorithm into space. Furthermore a population of low energy field-aligned electrons was detected by the TC2 PEACE instrument contemporaneous with the ULF waves in space. These electrons appear to be associated with an enhancement of field-aligned Poynting flux into the ionosphere which is large enough to power visible auroral displays. The observations are most consistent with a near-Earth initiation of substorm expansion phase onset, such as the Near Geosynchronous Onset (NGO) substorm scenario. A lack of data from further downtail, however, means other mechanisms cannot be ruled out.

  10. Comprehensive ground-based and in situ observations of substorm expansion phase onset

    NASA Astrophysics Data System (ADS)

    Walsh, A. P.; Rae, I. J.; Fazakerley, A. N.; Murphy, K. R.; Mann, I. R.; Watt, C. E. J.; Volwerk, M.; Forsyth, C.; Singer, H. J.; Donovan, E. F.; Zhang, T. L.

    2010-12-01

    In this paper, we present comprehensive ground-based and space-based in situ geosynchronous observations of a substorm expansion phase onset on 1 October 2005. The Double Star TC-2 and GOES-12 spacecraft were both located within the substorm current wedge during the substorm expansion phase onset, which occurred over the Canadian sector. We find that an onset of ULF waves in space was observed after onset on the ground by extending the AWESOME timing algorithm into space. Furthermore, a population of low-energy field-aligned electrons was detected by the TC-2 PEACE instrument contemporaneous with the ULF waves in space. These electrons appear to be associated with an enhancement of field-aligned Poynting flux into the ionosphere which is large enough to power visible auroral displays. The observations are most consistent with a near-Earth initiation of substorm expansion phase onset, such as the Near-Geosynchronous Onset (NGO) substorm scenario. A lack of data from further downtail, however, means other mechanisms cannot be ruled out.

  11. A Multiagent Robotic System for In-Situ Modeling and Observation of Icebergs

    NASA Astrophysics Data System (ADS)

    Coogle, R. A.; Howard, A.

    2013-12-01

    Ships that operate in polar regions continue to face the threat of floating ice sheets and icebergs generated from ice ablation processes. Systems have been implemented to track these threats, with varying degrees of success. We propose a definition of this tracking problem that re-casts it within a class of robotic, multiagent target observation problems. The focus in this new definition is on minimization of the time an initial contact for newly generated targets is obtained, as opposed to obtaining target contacts long after a target has been generated from a source. Focusing on the initial contact time provides for the ability to enact early countermeasures. A probabilistic model that can be computed in-situ by the robotic agents is presented for the target sources (e.g, iceberg calving regions), and methods of extracting information from that model are provided. Algorithms for computing costs associated with the model for reallocating robotic agents during an observation task and determining the behavior of the targets within the model are presented. The effectiveness of these solutions is demonstrated by comparison with an existing observation technique using simulation, and an implementation is provided for a real hardware system that models the type of system that would be required.

  12. Time-resolved in-situ observation of starch polysaccharide degradation pathways.

    PubMed

    Beeren, Sophie R; Petersen, Bent O; Bøjstrup, Marie; Hindsgaul, Ole; Meier, Sebastian

    2013-12-16

    Analytical challenges in the direct time-resolved observation of starch metabolism have been addressed by using optimized multidimensional NMR experiments. Starch provides the main source of human dietary energy intake and is a raw material for beverage and renewable fuel production. Use of direct in situ observations of starch remodeling pathways could facilitate our understanding and control of processes of biotechnological, medical, and environmental relevance. Processes involving starch synthesis or degradation are difficult to monitor directly in aqueous solution, however, because starch consists of glucopyranosyl homopolymers that are built up from and degraded into structurally similar fragments that yield only small signal dispersion in optical and NMR spectroscopy. By focusing on acetal groups only, (1) H,(13) C HSQC experiments sampling narrow spectral windows in the highly resolved (13) C dimension have been employed in order to observe the amylopectin cleavage pathway in real time with a temporal resolution of 150 s. Quantifiable signals for more than 15 molecular species emerging during starch fragmentation by human saliva have been resolved and tracked over time in this manner. Altered accumulation of intermediates in the digestion of amylopectin in the presence of black tea acting as an effector have been monitored.

  13. Paddy field mapping and yield estimation by satellite imagery and in situ observations

    NASA Astrophysics Data System (ADS)

    Oyoshi, K.; Sobue, S.

    2011-12-01

    Since Asian countries are responsible for approximately 90% of the world rice production and consumptions, rice is the most significant cereal crop in Asia. In order to ensure food security and take mitigation strategies or policies to manage food shortages, timely and accurate statistics of rice production are essential. It is time and cost consuming work to create accurate statistics of rice production by ground-based measurements. Hence, satellite remote sensing is expected to contribute food security through the systematic collection of food security related information such as crop growth or yield estimation. In 2011, Japan Aerospace Exploration Agency (JAXA) is collaborating with GISTDA (Geo-Informatics and Space Technology Development Agency, Thailand) in research projects of rice yield estimation by integrating satellite imagery and in situ data. Thailand is one of the largest rice production countries and the largest rice exporting country, therefore rice related statistics are imperative for food security and economy in the country. However, satellite observation by optical sensor in tropics including Thailand is highly limited, because the area is frequently covered by cloud. In contrast, Japanese microwave sensor, namely Phased-Array L-Band Synthetic Aperture Radar (PALSAR) on board Advanced Land Observing Satellite (ALOS) is suitable for monitoring cloudy area such as Southeast Asia, because PALSAR can penetrate clouds and collect land-surface information even if the area is covered by cloud. In this study, rice crop yield over Khon Kaen, northeast part of Thailand was estimated by combining satellite imagery and in-situ observation. This study consists of mainly two parts, paddy field mapping and yield estimation by numerical crop model. First, paddy field areas were detected by integrating PALSAR and AVNIR-2 data. PALSAR imagery has much speckle noise and the border of each landcover is ambiguous compared to that of optical sensor. To overcome this

  14. An initial assessment of SMAP soil moisture retrievals using high-resolution model simulations and in situ observations

    NASA Astrophysics Data System (ADS)

    Pan, Ming; Cai, Xitian; Chaney, Nathaniel W.; Entekhabi, Dara; Wood, Eric F.

    2016-09-01

    At the end of its first year of operation, we compare soil moisture retrievals from the Soil Moisture Active Passive (SMAP) mission to simulations from a land surface model with meteorological forcing downscaled from observations/reanalysis and in situ observations from sparse monitoring networks within continental United States (CONUS). The radar failure limits the duration of comparisons for the active and combined products (~3 months). Nevertheless, the passive product compares very well against in situ observations over CONUS. On average, SMAP compares to the in situ data even better than the land surface model and provides significant added value on top of the model and thus good potential for data assimilation. At large scale, SMAP is in good agreement with the model in most of CONUS with less-than-expected degradation over mountainous areas. Lower correlation between SMAP and the model is seen in the forested east CONUS and significantly lower over the Canadian boreal forests.

  15. Seasonal in situ observations of glyoxal and methylglyoxal over the temperate oceans of the Southern Hemisphere

    NASA Astrophysics Data System (ADS)

    Lawson, S. J.; Selleck, P. W.; Galbally, I. E.; Keywood, M. D.; Harvey, M. J.; Lerot, C.; Helmig, D.; Ristovski, Z.

    2015-01-01

    The dicarbonyls glyoxal and methylglyoxal have been measured with 2,4-dinitrophenylhydrazine (2,4-DNPH) cartridges and high-performance liquid chromatography (HPLC), optimised for dicarbonyl detection, in clean marine air over the temperate Southern Hemisphere (SH) oceans. Measurements of a range of dicarbonyl precursors (volatile organic compounds, VOCs) were made in parallel. These are the first in situ measurements of glyoxal and methylglyoxal over the remote temperate oceans. Six 24 h samples were collected in summer (February-March) over the Chatham Rise in the south-west Pacific Ocean during the Surface Ocean Aerosol Production (SOAP) voyage in 2012, while 34 24 h samples were collected at Cape Grim Baseline Air Pollution Station in the late winter (August-September) of 2011. Average glyoxal mixing ratios in clean marine air were 7 ppt at Cape Grim and 23 ppt over Chatham Rise. Average methylglyoxal mixing ratios in clean marine air were 28 ppt at Cape Grim and 10 ppt over Chatham Rise. The mixing ratios of glyoxal at Cape Grim are the lowest observed over the remote oceans, while mixing ratios over Chatham Rise are in good agreement with other temperate and tropical observations, including concurrent Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) observations. Methylglyoxal mixing ratios at both sites are comparable to the only other marine methylglyoxal observations available over the tropical Northern Hemisphere (NH) ocean. Ratios of glyoxal : methylglyoxal > 1 over Chatham Rise but < 1 at Cape Grim suggest that a different formation and/or loss processes or rates dominate at each site. Dicarbonyl precursor VOCs, including isoprene and monoterpenes, are used to calculate an upper-estimate yield of glyoxal and methylglyoxal in the remote marine boundary layer and explain at most 1-3 ppt of dicarbonyls observed, corresponding to 10% and 17% of the observed glyoxal and 29 and 10% of the methylglyoxal at Chatham Rise and Cape Grim

  16. Seasonal in situ observations of glyoxal and methylglyoxal over the temperate oceans of the Southern Hemisphere

    NASA Astrophysics Data System (ADS)

    Lawson, S. J.; Selleck, P. W.; Galbally, I. E.; Keywood, M. D.; Harvey, M. J.; Lerot, C.; Helmig, D.; Ristovski, Z.

    2014-08-01

    Dicarbonyls glyoxal and methylglyoxal have been measured with 2,4-dinitrophenylhydrazine (2,4-DNPH) cartridges and high performance liquid chromatography (HPLC), optimised for dicarbonyl detection, in clean marine air over the temperate Southern Hemisphere (SH) oceans. Measurements of a range of dicarbonyl precursors (volatile organic compounds, VOCs) were made in parallel. These are the first in situ measurements of glyoxal and methylglyoxal over the remote temperate oceans. Six 24 h samples were collected in late summer (February-March) over the Chatham Rise in the South West Pacific Ocean during the Surface Ocean Aerosol Production (SOAP) voyage in 2012, while 34 24 h samples were collected at Cape Grim Baseline Air Pollution Station in late winter (August-September) 2011. Average glyoxal mixing ratios in clean marine air were 7 ppt at Cape Grim, and 24 ppt over Chatham Rise. Average methylglyoxal mixing ratios in clean marine air were 28 ppt at Cape Grim and 12 ppt over Chatham Rise. The mixing ratios of glyoxal at Cape Grim are the lowest observed over the remote oceans, while mixing ratios over Chatham Rise are in good agreement with other temperate and tropical observations, including concurrent MAX-DOAS observations. Methylglyoxal mixing ratios at both sites are comparable to the only other marine methylglyoxal observations available over the tropical Northern Hemisphere (NH) ocean. Ratios of glyoxal : methylglyoxal > 1 over Chatham Rise but < 1 at Cape Grim, suggesting different formation and/or loss processes or rates dominate at each site. Dicarbonyl precursor VOCs, including isoprene and monoterpenes, are used to calculate an upper estimate yield of glyoxal and methylglyoxal in the remote marine boundary layer and explain at most 1-3 ppt of dicarbonyls observed, corresponding to 11 and 17% of the observed glyoxal and 28 and 10% of the methylglyoxal at Chatham Rise and Cape Grim, respectively, highlighting a significant but as yet unknown production

  17. Investigating Baseline, Alternative and Copula-based Algorithm for combining Airborne Active and Passive Microwave Observations in the SMAP Context

    NASA Astrophysics Data System (ADS)

    Montzka, C.; Lorenz, C.; Jagdhuber, T.; Laux, P.; Hajnsek, I.; Kunstmann, H.; Entekhabi, D.; Vereecken, H.

    2015-12-01

    The objective of the NASA Soil Moisture Active & Passive (SMAP) mission is to provide global measurements of soil moisture and freeze/thaw states. SMAP integrates L-band radar and radiometer instruments as a single observation system combining the respective strengths of active and passive remote sensing for enhanced soil moisture mapping. Airborne instruments will be a key part of the SMAP validation program. Here, we present an airborne campaign in the Rur catchment, Germany, in which the passive L-band system Polarimetric L-band Multi-beam Radiometer (PLMR2) and the active L-band system F-SAR of DLR were flown simultaneously on the same platform on six dates in 2013. The flights covered the full heterogeneity of the area under investigation, i.e. all types of land cover and experimental monitoring sites with in situ sensors. Here, we used the obtained data sets as a test-bed for the analysis of three active-passive fusion techniques: A) The SMAP baseline algorithm: Disaggregation of passive microwave brightness temperature by active microwave backscatter and subsequent inversion to soil moisture, B), the SMAP alternative algorithm: Estimation of soil moisture by passive sensor data and subsequent disaggregation by active sensor backscatter and C) Copula-based combination of active and passive microwave data. For method C empirical Copulas were generated and theoretical Copulas fitted both on the level of the raw products brightness temperature and backscatter as well as two soil moisture products. Results indicate that the regression parameters for method A and B are dependent on the radar vegetation index (RVI). Similarly, for method C the best performance was gained by generating separate Copulas for individual land use classes. For more in-depth analyses longer time series are necessary as can obtained by airborne campaigns, therefore, the methods will be applied to SMAP data.

  18. Direct in situ observation of nanoparticle synthesis in a liquid crystal surfactant template.

    PubMed

    Parent, Lucas R; Robinson, David B; Woehl, Taylor J; Ristenpart, William D; Evans, James E; Browning, Nigel D; Arslan, Ilke

    2012-04-24

    Controlled and reproducible synthesis of tailored materials is essential in many fields of nanoscience. In order to control synthesis, there must be a fundamental understanding of nanostructure evolution on the length scale of its features. Growth mechanisms are usually inferred from methods such as (scanning) transmission electron microscopy ((S)TEM), where nanostructures are characterized after growth is complete. Such post mortem analysis techniques cannot provide the information essential to optimize the synthesis process, because they cannot measure nanostructure development as it proceeds in real time. This is especially true in the complex rheological fluids used in preparation of nanoporous materials. Here we show direct in situ observations of synthesis in a highly viscous lyotropic liquid crystal template on the nanoscale using a fluid stage in the STEM. The nanoparticles nucleate and grow to ∼5 nm particles, at which point growth continues through the formation of connections with other nanoparticles around the micelles to form clusters. Upon reaching a critical size (>10-15 nm), the clusters become highly mobile in the template, displacing and trapping micelles within the growing structure to form spherical, porous nanoparticles. The final products match those synthesized in the lab ex situ. This ability to directly observe synthesis on the nanoscale in rheological fluids, such as concentrated aqueous surfactants, provides an unprecedented understanding of the fundamental steps of nanomaterial synthesis. This in turn allows for the synthesis of next-generation materials that can strongly impact important technologies such as organic photovoltaics, energy storage devices, catalysis, and biomedical devices.

  19. In situ TEM observation of lithium nanoparticle growth and morphological cycling.

    PubMed

    Ghatak, Jay; Guan, Wei; Möbus, Günter

    2012-03-01

    Lithium fluoride crystals were subjected to electron beam irradiation at 200 and 300 keV using transmission electron microscopy in order to study in situ fabrication of Li nanostructures. We observed that LiF crystals decompose in a unique way different to all other metal halides: Fluorine ablation and salt-to-metal conversion is non-local and due to a rapid lateral diffusion of Li, the life cycle from nucleation to annihilation of fresh Li nano-crystals can be observed at a distance from the Li-source, the irradiated salt. Growth, shape transition and annihilation of Li nanostructures follow at slow enough speed for live video recording with resolution of 25 frames per second. The equilibrium shapes of pure Li nano-crystals range from cubic to rod-shaped and ball-shaped and up to 300 nm size. By varying the e-beam flux of irradiation, transitions from cube to spherical shape can be induced cyclically.

  20. Enhanced sulfate formation by nitrogen dioxide: Implications from in situ observations at the SORPES station

    NASA Astrophysics Data System (ADS)

    Xie, Yuning; Ding, Aijun; Nie, Wei; Mao, Huiting; Qi, Ximeng; Huang, Xin; Xu, Zheng; Kerminen, Veli-Matti; Petäjä, Tuukka; Chi, Xuguang; Virkkula, Aki; Boy, Michael; Xue, Likun; Guo, Jia; Sun, Jianning; Yang, Xiuqun; Kulmala, Markku; Fu, Congbin

    2015-12-01

    Investigating sulfate formation processes is important not only for air pollution control but also for understanding the climate system. Although the mechanisms of secondary sulfate production have been widely studied, in situ observational evidence implicating an important role of NO2 in SO2 oxidation in the real atmosphere has been rare. In this study, we report two unique cases, from an intensive campaign conducted at the Station for Observing Regional Processes of the Earth System (SORPES) in East China, showing distinctly different mechanisms of sulfate formation by NO2 and related nitrogen chemistry. The first case occurred in an episode of mineral dust mixed with anthropogenic pollutants and especially high concentrations of NOx. It reveals that NO2 played an important role, not only in surface catalytic reactions of SO2 but also in dust-induced photochemical heterogeneous reactions of NO2, which produced additional sources of OH radicals to promote new particle formation and growth. The second case was caused by aqueous oxidation of S(IV) by NO2 under foggy/cloudy conditions with high NH3 concentration. As a by-product, the formed nitrite enhanced HONO formation and further promoted the gas-phase formation of sulfate in the downwind area. This study highlights the effect of NOx in enhancing the atmospheric oxidizing capacity and indicates a potentially very important impact of increasing NOx on particulate pollution formation and regional climate change in East Asia.

  1. In-Situ Observations of a Subglacial Outflow Plume in a Greenland Fjord

    NASA Astrophysics Data System (ADS)

    Mankoff, K. D.; Straneo, F.; Singh, H.; Das, S. B.

    2014-12-01

    We present oceanographic observations collected in and immediately outside of a buoyant, fresh, sediment-laden subglacial outflow plume rising up the marine-terminating front of Sarqardleq Glacier, Greenland (68.9 N, 50.4 W). Subglacial outflow plumes, associated with the discharge at depth of upstream glacial surface melt, entrain the relatively warm fjord waters and are correlated with enhanced submarine melt and increased calving. Few in-situ observations exist due to the challenges of making measurements at the calving front of glaciers. Our data were collected using a small boat, a helicopter, and a JetYak (a remote-controlled jet-ski-powered kayak). Temperature and salinity profiles in, around, and far from the plume are used to described its oceanographic properties, spatial extent, and temporal variability. This plume rises vertically up the ice front expanding laterally and away from the ice, over-shoots its stable isopycnal and reaches the surface. Its surface expression is identified by colder, saltier, sediment-laden water flowing at ~5 m/s away from the ice face. Within ~300 m from the ice it submerges as it seeks buoyant stability.

  2. In-situ TEM observation of dislocation evolution in Kr-irradiated UO2 single crystal

    SciTech Connect

    Lingfeng He; Mahima Gupta; Clarissa A. Yablinsky; Jian Gan; Marquis A. Kirk; Xian-Ming Bai; Janne Pakarinen; Todd R. Allen

    2013-11-01

    In-situ transmission electron microscopy (TEM) observation of UO2 single crystal irradiated with Kr ions at high temperatures was conducted to understand the dislocation evolution due to high-energy radiation. The dislocation evolution in UO2 single crystal is shown to occur as nucleation and growth of dislocation loops at low-irradiation doses, followed by transformation to extended dislocation segments and networks at high doses, as well as shrinkage and annihilation of some loops and dislocations due to high temperature annealing. Generally the trends of dislocation evolution in UO2 are similar under Kr irradiation at different ion energies and temperatures (150 keV at 600 degrees C and 1 MeV at 800 degrees C) used in this work, although the specific dislocation loop size and density are quite different. Interstitial-type dislocation loops with Burgers vector along <110> were observed in the Kr-irradiated UO2.The irradiated specimens were denuded of dislocation loops near the surface.

  3. In Situ Observation of the Electrochemical Lithiation of a Single SnO2 Nanowire Electrode

    SciTech Connect

    Huang, J Y; Zhong, L; Wang, C M; Sullivan, J P; Xu, W; Zhang, L Q; Mao, S X; Hudak, N S; Liu, X H; Subramanian, A; Fan, H Y; Qi, L A; Kushima, A; Li, J

    2010-12-09

    We report the creation of a nanoscale electrochemical device inside a transmission electron microscope—consisting of a single tin dioxide (SnO{sub 2}) nanowire anode, an ionic liquid electrolyte, and a bulk lithium cobalt dioxide (LiCoO{sub 2}) cathode—and the in situ observation of the lithiation of the SnO{sub 2} nanowire during electrochemical charging. Upon charging, a reaction front propagated progressively along the nanowire, causing the nanowire to swell, elongate, and spiral. The reaction front is a “Medusa zone” containing a high density of mobile dislocations, which are continuously nucleated and absorbed at the moving front. This dislocation cloud indicates large in-plane misfit stresses and is a structural precursor to electrochemically driven solid-state amorphization. Because lithiation-induced volume expansion, plasticity, and pulverization of electrode materials are the major mechanical effects that plague the performance and lifetime of high-capacity anodes in lithium-ion batteries, our observations provide important mechanistic insight for the design of advanced batteries.

  4. In Situ Observation on Dislocation-Controlled Sublimation of Mg Nanoparticles.

    PubMed

    Yu, Qian; Mao, Min-Min; Li, Qing-Jie; Fu, Xiao-Qian; Tian, He; Li, Ji-Xue; Mao, Scott X; Zhang, Ze

    2016-02-10

    Sublimation is an important endothermic phase transition in which the atoms break away from their neighbors in the crystal lattice and are removed into the gas phase. Such debonding process may be significantly influenced by dislocations, the crystal defect that changes the bonding environment of local atoms. By performing systematic defects characterization and in situ transmission electron microscopy (TEM) tests on a core--shell MgO-Mg system, which enables us to "modulate" the internal dislocation density, we investigated the role of dislocations on materials' sublimation with particular focus on the sublimation kinetics and mechanism. It was observed that the sublimation rate increases significantly with dislocation density. As the density of screw dislocations is high, the intersection of screw dislocation spirals creates a large number of monatomic ledges, resulting in a "liquid-like" motion of solid-gas interface, which significantly deviates from the theoretically predicted sublimation plane. Our calculation based on density functional theory demonstrated that the remarkable change of sublimation rate with dislocation density is due to the dramatic reduction in binding energy of the monatomic ledges. This study provides direct observation to improve our understanding on this fundamental phase transition as well as to shed light on tuning materials' sublimation by "engineering" dislocation density in applications. PMID:26799861

  5. The MyOcean Thematic Assembly Centres: Satellite and In-situ Observation Services in Review

    NASA Astrophysics Data System (ADS)

    Hackett, Bruce; Breivik, Lars-Anders; Larnicol, Gilles; Pouliquen, Sylvie; Santoleri, Rosalia; Roquet, Hervé; Stoffelen, Ad

    2015-04-01

    The MyOcean (2009-2012), MyOcean2 (2012-2014) and MyOcean Follow-On (October 2014 - March 2015) projects, respectively funded by the EU's 7th Framework Programme for Research (FP7 2007-2013) and HORIZON 2020 (EU Research and Innovation programme 2014-2020), have been designed to prepare and to lead the demonstration phases of the nascent European Copernicus Marine Environment Monitoring Service (CMS). The observational component of the MyOcean services is embodied in four Thematic Assembly Centres (TACs): Three provide satellite-based products for sea level (SL-TAC), for ocean colour (OC-TAC) and for surface temperature, winds and sea ice (OSI-TAC), while the fourth provides in-situ observations (INS-TAC). All the TAC production is developed from existing capabilities and there is close collaboration with related national and European data providers. Data products include near-real-time data and multi-year reprocessed datasets. Data formatting, dissemination methods and documentation follow uniform MyOcean standards for ease of use. The presentation will track the evolution of the TAC services through the MyOcean projects up to the opening of the CMS.

  6. In-situ observation of nucleated polymer crystallization in polyoxymethylene sandwich composites

    NASA Astrophysics Data System (ADS)

    Slouf, Miroslav; Krejcikova, Sabina; Vackova, Tatana; Kratochvil, Jaroslav; Novak, Libor

    2015-03-01

    We introduce a dynamic sandwich method, which can be used for in-situ observation and quantification of polymer crystallization nucleated by micro/nanoparticles. The method was applied on polyoxymethylene (POM) composites with three nucleating agents: talc micropowder (POM/mTalc), chalk nanopowder (POM/nChalk) and titanate nanotubes (POM/TiNT). The nucleating agents were deposited between polymer films, the resulting sandwich samples were consolidated by thermal treatment, and their microtomed cross-sections were observed during isothermal crystallization by polarized light microscopy. As the intensity of polarized light was shown to be proportional to the relative crystallinity, the PLM results could be fitted to Avrami equation and the nucleating activity of all investigated particles could be quantified by means of Avrami parameters (n, k). The crystallization half-times increased reproducibly in the following order: POM/nChalk < POM/mTalc < POM/TiNT ~ POM. For strong nucleating agents (mTalc, nChalk), the crystallization kinetics corresponded to spontaneous crystallization starting from central nucleating layer, which was verified by computer simulations. The results were also confirmed by DSC. We concluded that the sandwich method is an efficient microscopic technique for detailed evaluation of nucleating activity of arbitrary micro/nanoparticles in polymer systems.

  7. In-situ observations of nonlinear wave particle interaction of electromagnetic ion cyclotron waves

    NASA Astrophysics Data System (ADS)

    Shoji, M.; Miyoshi, Y.; Keika, K.; Katoh, Y.; Angelopoulos, V.; Nakamura, S.; Omura, Y.

    2014-12-01

    Direct measurement method for the electromagnetic wave and space plasma interaction has been suggested by a computer simulation study [Katoh et al., 2013], so-called Wave Particle Interaction Analysis (WPIA). We perform the WPIA for rising tone electromagnetic ion cyclotron (EMIC) waves (so-called EMIC triggered emissions), of which generation mechanism is essentially the same as the chorus emissions. THEMIS observation data (EFI, FGM, and ESA) are used for the WPIA. In the WPIA, we calculate (1) the inner product of the wave electric field and the velocity of the energetic protons: Wint, (2) the inner product of the wave magnetic field and the velocity of the energetic protons: WBint, and (3) the phase angle ζ between the wave magnetic field and the perpendicular velocity of the energetic protons. The values of (1) and (2) indicate the existence of the resonant currents inducing the nonlinear wave growth and the frequency change, respectively. We find the negative Wint and positive WBint at the nonlinear growing phase of the triggered emission as predicted in the theory [e.g. Omura and Nunn, 2011, Shoji and Omura, 2013]. In histogram of (3), we show the existence of the electromagnetic proton holes in the phase space generating the resonant currents. We also perform a hybrid simulation and evaluate WPIA method for EMIC waves. The simulation results show good agreement with the in-situ THEMIS observations.

  8. How in-situ observations challenge our understanding of cometary activity

    NASA Astrophysics Data System (ADS)

    Vincent, Jean-Baptiste

    2016-07-01

    "Cometary activity" is traditionally summarized as the combination of the sublimation of volatile material and the acceleration of refractories elements leading to a gas and dust coma around the nucleus. In-situ observations have shown that, although correct, this description is not sufficient. Volatiles are scarce on the surface of cometary nuclei, and the activity patterns are far more complex than initially thought. One example of the problems to solve is to understand how gas and dust can arise from the nucleus as collimated streams, often called "jets". ESA's Giotto observed these features for the first time 30 years ago but their formation mechanism remains to be explained. The Rosetta mission is now providing a continuous monitoring of a nucleus activity at high spatial and temporal resolution. We observed various types of activity, from narrow jets on a few meters scale to large structures extending 10s of kilometers from the nucleus. Overall the activity is quite homogeneously distributed, following closely the insolation pattern and repeating itself from one rotation to the other. We find however that some types of surfaces are more prone to create jets than others, reflecting local inhomogeneities in the topography and/or the volatile content. In addition to the typical jets, we also observed many transient events close to perihelion approach: sudden and massive releases of gas and dust for short times (<10min) which cannot be explained with the standard activity models. This presentation will review the different types of activity we have observed, and discuss how the Rosetta data challenges the current models.

  9. Direct observation of phase transitions: in situ diffraction measurements at the crystal scale

    NASA Astrophysics Data System (ADS)

    Bernier, J. V.; Barton, N. R.; Farber, D.; Wenk, H.; Kunz, M.; Lienert, U.

    2012-12-01

    Phase transitions often display determinate crystallographic orientation relationships between parent and symmetrically degenerate daughter domains. Preferred variant selection and orientation memory under the influence of deviatoric stress are the 'fingerprints' of the transformation mechanism, driving force, and microstructure. For the α-ɛ transition in iron - significant to the structure and anisotropy of the Earth's inner core - these have been studied primarily by texture analysis of polycrystalline powders; the convoluted nature of these data, however, render it essentially impossible to examine variant selection, and even precise orientation relationships themselves. Recently developed X-ray diffraction techniques have made it possible to answer these questions. Results from two measurements are presented. First, heterogeneous variant selection was observed and the specific α/ɛ orientation relationship was determined under quasi-static loading using High Energy Diffraction Microscopy at beamline 1-ID of APS-ANL. Second, the spatial heterogeneity and mutual exclusivity among ɛ variants was observed at the incipient transition using the Laue μ-diffraction technique at beamline 12.3.2. of ALS-LBNL. In both cases, a 60x25μm single crystal of iron was pressurized in a DAC and measured before and after the α-ɛ transition at 13GPa. In the HEDM experiment, spatial resolution is sacrificed for domain-averaged orientation and strain resoltuion, making it possible to quantify the magnitude of the applied deviatoric stress in situ. In the Laue μ-Diffraction technique, the local lattice orientations are mapped with 1μm resolution, displaying marked spatial variation. These pilot experiments open new possibilities for investigating high pressure/high temperature transformations in situ. By mapping both orientations and lattice strains, the nature of the mechanisms and driving forces can be illuminated. This work was performed under the auspices of the U

  10. NASA DC-8 Airborne Scanning Lidar Cloud and Contrail Observations

    NASA Technical Reports Server (NTRS)

    Uthe, Edward E.; Oseberg, Terje E.; Nielsen, Norman B.

    1997-01-01

    An angular scanning backscatter lidar has been developed and operated from the NASA DC-8 aircraft; the lidar viewing direction could be scanned from vertically upward to forward in the direction of aircraft travel to vertically downward. The scanning lidar was used to generate real-time video displays of clouds and contrails above, below, and ahead of the aircraft to aid in positioning the aircraft for achieving optimum cloud/contrail sampling by onboard in situ samplers. Data examples show that the lidar provides unique information for the interpretation of the other data records and that combined data analyses provides enhanced evaluations of contrail/cloud structure, dynamics, composition, and optical/radiative properties.

  11. Simultaneous observations of atmospheric tides from combined in situ and remote observations at Mars from the MAVEN spacecraft

    NASA Astrophysics Data System (ADS)

    England, Scott L.; Liu, Guiping; Withers, Paul; Yiǧit, Erdal; Lo, Daniel; Jain, Sonal; Schneider, Nicholas M.; Deighan, Justin; McClintock, William E.; Mahaffy, Paul R.; Elrod, Meredith; Benna, Mehdi; Jakosky, Bruce M.

    2016-04-01

    We report the observations of longitudinal variations in the Martian thermosphere associated with nonmigrating tides. Using the Neutral Gas Ion Mass Spectrometer (NGIMS) and the Imaging Ultraviolet Spectrograph (IUVS) on NASA's Mars Atmosphere and Volatile EvolutioN Mission (MAVEN) spacecraft, this study presents the first combined analysis of in situ and remote observations of atmospheric tides at Mars for overlapping volumes, local times, and overlapping date ranges. From the IUVS observations, we determine the altitude and latitudinal variation of the amplitude of the nonmigrating tidal signatures, which is combined with the NGIMS, providing information on the compositional impact of these waves. Both the observations of airglow from IUVS and the CO2 density observations from NGIMS reveal a strong wave number 2 signature in a fixed local time frame. The IUVS observations reveal a strong latitudinal dependence in the amplitude of the wave number 2 signature. Combining this with the accurate CO2 density observations from NGIMS, this would suggest that the CO2 density variation is as high as 27% at 0-10° latitude. The IUVS observations reveal little altitudinal dependence in the amplitude of the wave number 2 signature, varying by only 20% from 160 to 200 km. Observations of five different species with NGIMS show that the amplitude of the wave number 2 signature varies in proportion to the inverse of the species scale height, giving rise to variation in composition as a function of longitude. The analysis and discussion here provide a roadmap for further analysis as additional coincident data from these two instruments become available.

  12. Towards soil property retrieval from space: Proof of concept using in situ observations

    NASA Astrophysics Data System (ADS)

    Bandara, Ranmalee; Walker, Jeffrey P.; Rüdiger, Christoph

    2014-05-01

    Soil moisture is a key variable that controls the exchange of water and energy fluxes between the land surface and the atmosphere. However, the temporal evolution of soil moisture is neither easy to measure nor monitor at large scales because of its high spatial variability. This is mainly a result of the local variation in soil properties and vegetation cover. Thus, land surface models are normally used to predict the evolution of soil moisture and yet, despite their importance, these models are based on low-resolution soil property information or typical values. Therefore, the availability of more accurate and detailed soil parameter data than are currently available is vital, if regional or global soil moisture predictions are to be made with the accuracy required for environmental applications. The proposed solution is to estimate the soil hydraulic properties via model calibration to remotely sensed soil moisture observation, with in situ observations used as a proxy in this proof of concept study. Consequently, the feasibility is assessed, and the level of accuracy that can be expected determined, for soil hydraulic property estimation of duplex soil profiles in a semi-arid environment using near-surface soil moisture observations under naturally occurring conditions. The retrieved soil hydraulic parameters were then assessed by their reliability to predict the root zone soil moisture using the Joint UK Land Environment Simulator model. When using parameters that were retrieved using soil moisture observations, the root zone soil moisture was predicted to within an accuracy of 0.04 m3/m3, which is an improvement of ∼0.025 m3/m3 on predictions that used published values or pedo-transfer functions.

  13. CAROLS: A New Airborne L-Band Radiometer for Ocean Surface and Land Observations

    PubMed Central

    Zribi, Mehrez; Pardé, Mickael; Boutin, Jacquline; Fanise, Pascal; Hauser, Daniele; Dechambre, Monique; Kerr, Yann; Leduc-Leballeur, Marion; Reverdin, Gilles; Skou, Niels; Søbjærg, Sten; Albergel, Clement; Calvet, Jean Christophe; Wigneron, Jean Pierre; Lopez-Baeza, Ernesto; Rius, Antonio; Tenerelli, Joseph

    2011-01-01

    The “Cooperative Airborne Radiometer for Ocean and Land Studies” (CAROLS) L-Band radiometer was designed and built as a copy of the EMIRAD II radiometer constructed by the Technical University of Denmark team. It is a fully polarimetric and direct sampling correlation radiometer. It is installed on board a dedicated French ATR42 research aircraft, in conjunction with other airborne instruments (C-Band scatterometer—STORM, the GOLD-RTR GPS system, the infrared CIMEL radiometer and a visible wavelength camera). Following initial laboratory qualifications, three airborne campaigns involving 21 flights were carried out over South West France, the Valencia site and the Bay of Biscay (Atlantic Ocean) in 2007, 2008 and 2009, in coordination with in situ field campaigns. In order to validate the CAROLS data, various aircraft flight patterns and maneuvers were implemented, including straight horizontal flights, circular flights, wing and nose wags over the ocean. Analysis of the first two campaigns in 2007 and 2008 leads us to improve the CAROLS radiometer regarding isolation between channels and filter bandwidth. After implementation of these improvements, results show that the instrument is conforming to specification and is a useful tool for Soil Moisture and Ocean Salinity (SMOS) satellite validation as well as for specific studies on surface soil moisture or ocean salinity. PMID:22346599

  14. Application of Airborne Sea Ice Observations Towards Improving Satellite-based Products

    NASA Astrophysics Data System (ADS)

    Tschudi, M. A.; Baldwin, D.; Liu, Y.; Dworak, R.; Key, J.

    2015-12-01

    Recent airborne and satellite observations suggest large decreases in Arctic sea ice thickness in recent years, but uncertainty remains in terms of overall loss of ice mass versus redistribution of mass within the Arctic Basin. In general though, the combination of airborne and satellite observations tend to agree that some thinning of the ice cover has occurred. In addition to changes in ice thickness and mass, other related changes in properties are likely if the ice pack is undergoing fundamental changes such as a shift to a largely seasonal sea-ice cover. Therefore, it is imperative to utilize airborne and surface-based observations to evaluate satellite-based sea ice products and to improve algorithms that estimate sea ice properties. Sea ice surface properties derived from NASA's Operation IceBridge (OIB) airborne measurements are currently being used to evaluate and update Suomi-NPP VIIRS sea ice products. Estimates of ice thickness derived from the OIB observations may be used to establish a relationship between sea ice thickness and the age of the ice. Drifting buoys serve to improve errors in tracking the movement of ice parcels through Arctic waters. Future airborne measurements of spectral reflectance during the melt season will improve algorithms that estimate melt pond fraction. We present examples of airborne validation of VIIRS sea ice products, relationships between sea ice thickness estimated from OIB measurements and sea ice age, and demonstrate the need for future airborne high-resolution estimates of surface reflectance, particularly in melt ponds. OIB thickness estimates over one sea ice age cell (12.5 km box) are shown in the attached figure.

  15. Direct observation of zeolite a synthesis by in situ solid-state NMR

    SciTech Connect

    Shi, J.; Anderson, M.W.; Carr, S.W.

    1996-02-01

    This paper describes the use of in situ solid-state NMR and X-ray powder diffraction to study the real-time synthesis of zeolite. In particular {sup 27}Al and {sup 29}Si are used to monitor the growth in situ X-ray diffraction study was used to investigate the development of long range order of the material. Conclusions concerning the mechanism of the formation of zeolite A are proposed. 28 refs., 12 figs., 2 tabs.

  16. In situ observation of microcrack growth in 8090-T[sub 4] alloy

    SciTech Connect

    Zhang Yun; Xu Yongbo; Liu Yulin; Ai Suhua; Zhao Hongen; Hu Zhangqi . Inst. of Metal Research)

    1993-09-01

    Aluminum-lithium alloys have become of recent interest as potentially important aerospace structural materials because of their low density, high elastic modulus and strength. However, some Al-Li alloys show very low tensile ductility and fracture toughness, particularly at peak-aged conditions. Vasudevan and Starke et al. recognized that Al-Li alloys were highly sensitive to intergranular fracture. Noble emphasized the effect of strain localization at coarse slip bands. Although much research has been published, the problem still has not been satisfactorily resolved. In contrast, the 8090-T[sub 4] alloy exhibits good comprehensive properties. In this paper, in situ observations in a TEM were carried out in the 8090-T[sub 4] alloy in order to study the deformation characteristics near the crack tip as well as microcrack growth. The results can be used to define the microstructure/property relationship in Al-Li alloys. Some results on fracture mechanisms at peak-and over-aged conditions will be reported later, so that the relationship between fracture mechanism, tensile ductility and the resistance to crack growth can be elucidated.

  17. Integration of space and in situ observations to study global climate change

    NASA Technical Reports Server (NTRS)

    Bengtsson, L.; Shukla, J.

    1988-01-01

    The use of model-based global data sets of atmospheric circulation for studying fundamental dynamical and physical processes is discussed, focusing on limitations of the available model-based data sets. Data from the Global Weather Experiment in 1979 were analyzed by two authorized level IIIb data centers in 1980 and in 1981. The analyses led to difference in data-sparse regions such as the tropics. Study areas which can be addressed by an internally-consistent long-term multivariate data set for the atmospheric circulation are considered, including mean climate, forcing for the ocean models, global hydrological cycle, atmospheric energetics, intraseasonal variability, land surface processes, and structure and variability of vertical velocity, divergence, and diabatic heating. It is concluded that the most comprehensive technique for integrating space and in situ observations to produce this type of data set would be a four-dimensional data assimilation system with a realistic physical model of the type employed in operational numerical weather prediction.

  18. In situ observation and analysis of faceted crystal growth process in REBCO superconductive oxide

    NASA Astrophysics Data System (ADS)

    Mori, N.; Nakahara, Y.; Ogi, K.; Mukaida, M.

    2007-10-01

    To clarify the nucleation and growth process of 123 crystals, growth of faceted RE123 (REBa2Cu3O7-X, RE = Nd, Sm, Gd, Y) crystals was observed in situ on MgO(1 0 0) by using high temperature optical microscope with zoom lens. RE123 crystals nucleated and grew at each undercooling (ΔT = 13-50 K). Growth rate (u) and incubation time (tinc) for nucleation were obtained from the relationship between the position of faceted interface and time (t). u increased with increasing ΔTr2 , where ΔTr = ΔT/Tp, Tp was peritectic temperature. Nucleation rate (Iv) was obtained from the relationship between the number of nucleated crystals (n) and time. Iv increased with increasing of exp (- B / ΔTr2), where B was a constant. Both u and Iv under a fixed ΔT increased with increasing Tp: u(Nd123) > u(Sm123) > u(Gd123) and Iv(Nd123) > Iv(Sm123) > Iv(Gd123) for Tp(Nd123) > Tp(Sm123) > Tp(Gd123) in Ar-1%O2 atmosphere.

  19. In situ observation and analysis of crystal growth process of GdBCO superconductive oxide

    NASA Astrophysics Data System (ADS)

    Nakahara, Y.; Inokawa, T.; Mori, N.; Ogi, K.

    2006-10-01

    To clarify the nucleation and growth process of 123 crystals, growth of faceted Gd123(GdBa2Cu3O7-δ) crystals was observed in situ on MgO(1 0 0) by using a high temperature optical microscope with zoom lens (×50-500). Gd123 crystals nucleated and grew at each undercooling (ΔT = 30, 35, 40, 45 K). Growth rate (u) and incubation time (tinc) for nucleation were obtained from the relationship between time and position of faceted interface. u was approximated by a function of ΔT: u =Agp ΔTr2 / η (T) , where Agp is a constant, Agp = 1.0 × 10-5. Nucleation rate (Iv) was obtained from the relationship between time and number of nucleated crystals. Iv was approximated by an exponential function: Iv = {An / η (T) } exp (- B / ΔTr2) , where An and B are constants, An = 1.3 × 107, B = 2.7 × 10-3. The nucleation and growth process of Gd123 crystals were expressed quantitatively by the above equations.

  20. In-situ Observations of the Ionospheric F2-Region from the International Space Station

    NASA Technical Reports Server (NTRS)

    Coffey, Victoria N.; Wright, Kenneth H.; Minow, Joseph I.; Chandler, Michael O.; Parker, Linda N.

    2008-01-01

    The International Space Station orbit provides an ideal platform for in-situ studies of space weather effects on the mid and low latitude F-2 region ionosphere. The Floating Potential Measurement Unit (FPMU) operating on the ISS since Aug 2006, is a suite of plasma instruments: a Floating Potential Probe (FPP), a Plasma Impedance Probe (PIP), a Wide-sweep Langmuir Probe (WLP), and a Narrow-sweep Langmuir Probe (NLP). This instrument package provides a new opportunity for collaborative multi-instrument studies of the F-region ionosphere during both quiet and disturbed periods. This presentation first describes the operational parameters for each of the FPMU probes and shows examples of an intra-instrument validation. We then show comparisons with the plasma density and temperature measurements derived from the TIMED GUVI ultraviolet imager, the Millstone Hill ground based incoherent scatter radar, and DIAS digisondes, Finally we show one of several observations of night-time equatorial density holes demonstrating the capabilities of the probes for monitoring mid and low latitude plasma processes.

  1. In-situ observation of bubble formation at silicon melt-silica glass interface

    NASA Astrophysics Data System (ADS)

    Minami, Toshiro; Maeda, Susumu; Higasa, Mitsuo; Kashima, Kazuhiko

    2011-03-01

    The generation mechanism of pinhole defects in the Czochralski (CZ)-grown silicon (Si) single crystals was clarified by in-situ observations of bubble formation at the interface between Si melt and a silica glass crucible in a small experimental apparatus. The nucleation and growth of bubbles were facilitated by creating small cavities on the inner wall of the crucible. Si melting was conducted in an argon (Ar) atmosphere, and the pressure was maintained at either 100 Torr or close to a vacuum (no Ar-gas flow). It was found that in the presence of Ar, bubbles formed in the cavities immediately after the cavities came in contact with the melt. However, no bubbles formed in a vacuum in the experimental apparatus. These results indicate that the bubbles formed in the cavities are largely filled with Ar, and the initial bubble volumes are nearly comparable with those of the cavities. In an initial stage of expansion of a bubble, estimated volumes changed nearly in accordance with the Boyle-Charles law. Further, participation of SiO gas in bubble growth may explain the deviation of the bubble volume from the theoretical value anticipated if only Ar gas was involved in the bubble growth.

  2. In situ observation of shear-driven amorphization in silicon crystals

    NASA Astrophysics Data System (ADS)

    He, Yang; Zhong, Li; Fan, Feifei; Wang, Chongmin; Zhu, Ting; Mao, Scott X.

    2016-10-01

    Amorphous materials are used for both structural and functional applications. An amorphous solid usually forms under driven conditions such as melt quenching, irradiation, shock loading or severe mechanical deformation. Such extreme conditions impose significant challenges on the direct observation of the amorphization process. Various experimental techniques have been used to detect how the amorphous phases form, including synchrotron X-ray diffraction, transmission electron microscopy (TEM) and Raman spectroscopy, but a dynamic, atomistic characterization has remained elusive. Here, by using in situ high-resolution TEM (HRTEM), we show the dynamic amorphization process in silicon nanocrystals during mechanical straining on the atomic scale. We find that shear-driven amorphization occurs in a dominant shear band starting with the diamond-cubic (dc) to diamond-hexagonal (dh) phase transition and then proceeds by dislocation nucleation and accumulation in the newly formed dh-Si phase. This process leads to the formation of an amorphous Si (a-Si) band, embedded with dh-Si nanodomains. The amorphization of dc-Si via an intermediate dh-Si phase is a previously unknown pathway of solid-state amorphization.

  3. Stratospheric Age Spectra and Mean Ages From In Situ Observations of Carbon Dioxide

    NASA Technical Reports Server (NTRS)

    Andrews, Arlyn E.; Boering, Kristie A.; Daube, Bruce C., Jr.; Wofsy, Steven C.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    Tropospheric CO2 mixing ratios exhibit latitudinally varying seasonal and interannual oscillations superimposed on the long-term positive trend due to fossil fuel combustion. In situ observations of CO2 obtained from 1992-2000 using the NASA ER-2 aircraft and high-altitude balloons show that these time-varying signals propagate into the stratosphere, providing information about the transport history of sampled air. We have used these data to derive age spectra and mean ages that can be compared with results from models of the stratospheric circulation. Age spectra have been derived for altitudes below approximately 20 km for the tropics and for northern midlatitudes, where there is sufficient data and where the amplitudes of the seasonal and interannual oscillations are large enough to be detected. The midlatitude CO2 data are consistent with bimodal age spectra, which may result from a subtropical "barrier" to horizontal exchange. Seasonally resolved mean ages are available with nearly pole-to-pole coverage below 20 km and in the tropics and at middle and high northern latitudes up to the maximum altitude reached by the balloons (approximately 30 km). The oldest air sampled was in the Arctic polar vortex with a mean age of 6.5 +/- 0.5 years.

  4. In situ observation of dislocation nucleation and escape in a submicrometre aluminium single crystal

    NASA Astrophysics Data System (ADS)

    Oh, Sang Ho; Legros, Marc; Kiener, Daniel; Dehm, Gerhard

    2009-02-01

    `Smaller is stronger' does not hold true only for nanocrystalline materials but also for single crystals. It is argued that this effect is caused by geometrical constraints on the nucleation and motion of dislocations in submicrometre-sized crystals. Here, we report the first in situ transmission electron microscopy tensile tests of a submicrometre aluminium single crystal that are capable of providing direct insight into source-controlled dislocation plasticity in a submicrometre crystal. Single-ended sources emit dislocations that escape the crystal before being able to multiply. As dislocation nucleation and loss rates are counterbalanced at about 0.2 events per second, the dislocation density remains statistically constant throughout the deformation at strain rates of about 10-4s-1. However, a sudden increase in strain rate to 10-3s-1 causes a noticeable surge in dislocation density as the nucleation rate outweighs the loss rate. This observation indicates that the deformation of submicrometre crystals is strain-rate sensitive.

  5. Constraints on CME Evolution from in situ Observations of Ionic Charge States

    NASA Technical Reports Server (NTRS)

    Gruesbeck, Jacob R.; Lepri, Susan T.; Zurbuchen, Thomas H.; Antiochos, Spiro K.

    2010-01-01

    We present a novel procedure for deriving the physical properties of Coronal Mass Ejections (CMES) in the corona. Our methodology uses in-situ measurements of ionic charge states of C, O, Si and Fe in the heliosphere and interprets them in the context of a model for the early evolution of ICME plasma, between 2 - 5 R-solar. We find that the data can be fit only by an evolution that consists of an initial heating of the plasma, followed by an expansion that ultimately results in cooling. The heating profile is consistent with a compression of coronal plasma due to flare reconnect ion jets and an expansion cooling due to the ejection, as expected from the standard CME/flare model. The observed frozen-in ionic charge states reflect this time-history and, therefore, provide important constraints for the heating and expansion time-scales, as well as the maximum temperature the CME plasma is heated to during its eruption. Furthermore, our analysis places severe limits on the possible density of CME plasma in the corona. We discuss the implications of our results for CME models and for future analysis of ICME plasma composition.

  6. In situ observation of containerless protein crystallization by magnetically levitating crystal growth

    NASA Astrophysics Data System (ADS)

    Maki, Syou; Tanimoto, Yoshifumi; Udagawa, Chikako; Morimoto, Shotaro; Hagiwara, Masayuki

    2016-03-01

    We report on the results of the crystal growth of hen-egg lysozyme by magnetically levitating crystals in a small amount of buffer solution. The concentrations of lysozyme and the precipitating agent (gadolinium chloride) were 6.53 wt % and 0.362 mol/kg, respectively. Gadolinium chloride, which induces the magneto-Archimedes effect, was utilized to levitate the crystals with Bz · (dBz/dz) = 22.46 T2/m, where Bz is the vertical (z) component of the magnetic flux density vector. Although the collected crystals were small, we succeeded in maintaining the levitation of the crystals into a specific place in the liquid phase from the beginning of nucleation. In situ observation revealed that a state of pseudo-weightlessness was generated in the vicinity of the magnet bore edge, and small crystals were concentrated inside the domain moving along an hourglass-shaped surface. We found by numerical computations that the formation of the hourglass-shaped domain is attributable to the radial component of the magnetic force.

  7. Elasticity of MoS2 Sheets by Mechanical Deformation Observed by in Situ Electron Microscopy

    PubMed Central

    2015-01-01

    MoS2 has been the focus of extensive research due to its potential applications. More recently, the mechanical properties of MoS2 layers have raised interest due to applications in flexible electronics. In this article, we show in situ transmission electron microcsopy (TEM) observation of the mechanical response of a few layers of MoS2 to an external load. We used a scanning tunneling microscope (STM) tip mounted on a TEM stage to induce deformation on nanosheets of MoS2 containing few layers. The results confirm the outstanding mechanical properties on the MoS2. The layers can be bent close to 180°. However, when the tip is retrieved the initial structure is recovered. Evidence indicates that there is a significant bond reconstruction during the bending with an outstanding capability to recover the initial bond structure. The results show that flexibility of three layers of MoS2 remains the same as a single layer while increasing the bending modulus by 3 orders of magnitude. Our findings are consistent with theoretical calculations and confirm the great potential of MoS2 for applications. PMID:25598860

  8. Dynamic in situ observation of voltage-driven repeatable magnetization reversal at room temperature.

    PubMed

    Gao, Ya; Hu, Jia-Mian; Nelson, C T; Yang, T N; Shen, Y; Chen, L Q; Ramesh, R; Nan, C W

    2016-03-31

    Purely voltage-driven, repeatable magnetization reversal provides a tantalizing potential for the development of spintronic devices with a minimum amount of power consumption. Substantial progress has been made in this subject especially on magnetic/ferroelectric heterostructures. Here, we report the in situ observation of such phenomenon in a NiFe thin film grown directly on a rhombohedral Pb(Mg1/3Nb2/3)0.7Ti0.3O3(PMN-PT) ferroelectric crystal. Under a cyclic voltage applied perpendicular to the PMN-PT without a magnetic field, the local magnetization of NiFe can be repetitively reversed through an out-of-plane excursion and then back into the plane. Using phase field simulations we interpret magnetization reversal as a synergistic effect of the metastable ferroelastic switching in the PMN-PT and an electrically rotatable local exchange bias field arising from the heterogeneously distributed NiO clusters at the interface.

  9. Riming in alpine snowfall during CLACE 2014: Polarimetric radar and in situ observations

    NASA Astrophysics Data System (ADS)

    Grazioli, Jacopo; Berne, Alexis

    2016-04-01

    Riming occurs when ice crystals or snowflakes encounter supercooled liquid water (SLW) droplets during their fall to the surface within a mixed-phase cloud. It is an efficient mechanism to convert cloud liquid droplets to precipitating ice particles, frequently seen in snowfall in the mid-latitude regions. This study investigates the microphysics of winter alpine snowfall occurring in mixed-phase clouds in an inner-Alpine valley during January and February 2014. The available observations include high-resolution polarimetric radar and in situ measurements of the ice-phase and liquid-phase components of clouds and precipitation. Radar-based hydrometeor classification suggests that riming is an important factor to favour an efficient growth of the precipitating mass and correlates with snow accumulation rates at ground level. The time steps during which rimed precipitation is dominant are analyzed in terms of temporal evolution and vertical structure. Snowfall identified as rimed often appears after a short time period during which the atmospheric conditions favour wind gusts and updrafts and supercooled liquid water (SLW) is available. When a turbulent atmospheric layer persists for several hours and ensures continuous SLW generation, riming can be sustained longer and large accumulations of snow at ground level can be generated. The microphysical interpretation and the meteorological situation associated with one such event are detailed in the presentation.

  10. In Situ Observation of the Dislocation Structure Evolution During a Strain Path Change in Copper

    NASA Astrophysics Data System (ADS)

    Wejdemann, Christian; Poulsen, Henning Friis; Lienert, Ulrich; Pantleon, Wolfgang

    2013-01-01

    The evolution of deformation structures in individual grains embedded in polycrystalline copper specimens during strain path changes is observed in situ by high-resolution reciprocal space mapping with high-energy synchrotron radiation. A large number of individual subgrains is resolved; their behavior during the strain path change is revealed and complemented by the analysis of radial x-ray peak profiles for the entire grain. This allows distinction between two different regimes during the mechanically transient behavior following the strain path change: Below 0.3% strain, the number and orientation of the resolved subgrains change only slightly, while their elastic stresses are significantly altered. This indicates the existence of a microplastic regime during which only the subgrains deform plastically and no yielding of the dislocation walls occurs. After reloading above 0.3% strain, the elastic stresses of individual subgrains are about the same as in unidirectionally deformed reference specimens. They increase only slightly during further straining—accompanied by occasional emergence of new subgrains, abundant orientation changes, and disappearance of existing subgrains.

  11. Dynamic in situ observation of voltage-driven repeatable magnetization reversal at room temperature

    NASA Astrophysics Data System (ADS)

    Gao, Ya; Hu, Jia-Mian; Nelson, C. T.; Yang, T. N.; Shen, Y.; Chen, L. Q.; Ramesh, R.; Nan, C. W.

    2016-03-01

    Purely voltage-driven, repeatable magnetization reversal provides a tantalizing potential for the development of spintronic devices with a minimum amount of power consumption. Substantial progress has been made in this subject especially on magnetic/ferroelectric heterostructures. Here, we report the in situ observation of such phenomenon in a NiFe thin film grown directly on a rhombohedral Pb(Mg1/3Nb2/3)0.7Ti0.3O3(PMN-PT) ferroelectric crystal. Under a cyclic voltage applied perpendicular to the PMN-PT without a magnetic field, the local magnetization of NiFe can be repetitively reversed through an out-of-plane excursion and then back into the plane. Using phase field simulations we interpret magnetization reversal as a synergistic effect of the metastable ferroelastic switching in the PMN-PT and an electrically rotatable local exchange bias field arising from the heterogeneously distributed NiO clusters at the interface.

  12. Dynamic in situ observation of voltage-driven repeatable magnetization reversal at room temperature.

    PubMed

    Gao, Ya; Hu, Jia-Mian; Nelson, C T; Yang, T N; Shen, Y; Chen, L Q; Ramesh, R; Nan, C W

    2016-01-01

    Purely voltage-driven, repeatable magnetization reversal provides a tantalizing potential for the development of spintronic devices with a minimum amount of power consumption. Substantial progress has been made in this subject especially on magnetic/ferroelectric heterostructures. Here, we report the in situ observation of such phenomenon in a NiFe thin film grown directly on a rhombohedral Pb(Mg1/3Nb2/3)0.7Ti0.3O3(PMN-PT) ferroelectric crystal. Under a cyclic voltage applied perpendicular to the PMN-PT without a magnetic field, the local magnetization of NiFe can be repetitively reversed through an out-of-plane excursion and then back into the plane. Using phase field simulations we interpret magnetization reversal as a synergistic effect of the metastable ferroelastic switching in the PMN-PT and an electrically rotatable local exchange bias field arising from the heterogeneously distributed NiO clusters at the interface. PMID:27029464

  13. Dynamic in situ observation of voltage-driven repeatable magnetization reversal at room temperature

    PubMed Central

    Gao, Ya; Hu, Jia-Mian; Nelson, C. T.; Yang, T. N.; Shen, Y.; Chen, L. Q.; Ramesh, R.; Nan, C. W.

    2016-01-01

    Purely voltage-driven, repeatable magnetization reversal provides a tantalizing potential for the development of spintronic devices with a minimum amount of power consumption. Substantial progress has been made in this subject especially on magnetic/ferroelectric heterostructures. Here, we report the in situ observation of such phenomenon in a NiFe thin film grown directly on a rhombohedral Pb(Mg1/3Nb2/3)0.7Ti0.3O3(PMN-PT) ferroelectric crystal. Under a cyclic voltage applied perpendicular to the PMN-PT without a magnetic field, the local magnetization of NiFe can be repetitively reversed through an out-of-plane excursion and then back into the plane. Using phase field simulations we interpret magnetization reversal as a synergistic effect of the metastable ferroelastic switching in the PMN-PT and an electrically rotatable local exchange bias field arising from the heterogeneously distributed NiO clusters at the interface. PMID:27029464

  14. New Platforms for Suborbital Astronomical Observations and In Situ Atmospheric Measurements: Spacecraft, Instruments, and Facilities

    NASA Astrophysics Data System (ADS)

    Rodway, K.; DeForest, C. E.; Diller, J.; Vilas, F.; Sollitt, L. S.; Reyes, M. F.; Filo, A. S.; Anderson, E.

    2014-12-01

    Suborbital astronomical observations have over 50 years' history using NASA's sounding rockets and experimental space planes. The new commercial space industry is developing suborbital reusable launch vehicles (sRLV's) to provide low-cost, flexible, and frequent access to space at ~100 km altitude. In the case of XCOR Aerospace's Lynx spacecraft, the vehicle design and capabilities work well for hosting specially designed experiments that can be flown with a human-tended researcher or alone with the pilot on a customized mission. Some of the first-generation instruments and facilities that will conduct solar observations on dedicated Lynx science missions include the SwRI Solar Instrument Pointing Platform (SSIPP) and Atsa Suborbital Observatory, as well as KickSat sprites, which are picosatellites for in situ atmospheric and solar phenomena measurements. The SSIPP is a demonstration two-stage pointed solar observatory that operates inside the Lynx cockpit. The coarse pointing stage includes the pilot in the feedback loop, and the fine stage stabilizes the solar image to achieve arcsecond class pointing. SSIPP is a stepping-stone to future external instruments that can operate with larger apertures and shorter wavelengths in the solar atmosphere. The Planetary Science Institute's Atsa Suborbital Observatory combines the strengths of ground-based observatories and space-based observing to create a facility where a telescope is maintained and used interchangeably with either in-house facility instruments or user-provided instruments. The Atsa prototype is a proof of concept, hand-guided camera that mounts on the interior of the Lynx cockpit to test target acquisition and tracking for human-operated suborbital astronomy. KickSat sprites are mass-producible, one inch printed circuit boards (PCBs) populated by programmable off the shelf microprocessors and radios for real time data transmission. The sprite PCBs can integrate chip-based radiometers, magnetometers

  15. Direct in situ observation of synergism between cellulolytic enzymes during the biodegradation of crystalline cellulose fibers.

    PubMed

    Wang, Jingpeng; Quirk, Amanda; Lipkowski, Jacek; Dutcher, John R; Clarke, Anthony J

    2013-12-01

    High-resolution atomic force microscopy (AFM) was used to image the real-time in situ degradation of crystalline by three types of T. reesei cellulolytic enzymes-TrCel6A, TrCel7A, and TrCel7B-and their mixtures. TrCel6A and TrCel7A are exo-acting cellobiohydrolases processing cellulose fibers from the nonreducing and reducing ends, respectively. TrCel7B is an endoglucanase that hydrolyzes amorphous cellulose within fibers. When acting alone on native cellulose fibers, each of the three enzymes is incapable of significant degradation. However, mixtures of two enzymes exhibited synergistic effects. The degradation effects of this synergism depended on the order in which the enzymes were added. Faster hydrolysis rates were observed when TrCel7A (exo) was added to fibers pretreated first with TrCel7B (endo) than when adding the enzymes in the opposite order. Endo-acting TrCel7B removed amorphous cellulose, softened and swelled the fibers, and exposed single microfibrils, facilitating the attack by the exo-acting enzymes. AFM images revealed that exo-acting enzymes processed the TrCel7B-pretreated fibers preferentially from one specific end (reducing or nonreducing). The most efficient (almost 100%) hydrolysis was observed with the mixture of the three enzymes. In this mixture, TrCel7B softened the fiber and TrCel6A and TrCel7A were directly observed to process it from the two opposing ends. This study provides high-resolution direct visualization of the nature of the synergistic relation between T. reesei exo- and endo-acting enzymes digesting native crystalline cellulose.

  16. Transmission Electron Microscope In Situ Straining Technique to Directly Observe Defects and Interfaces During Deformation in Magnesium

    DOE PAGES

    Morrow, Benjamin M.; Cerreta, E. K.; McCabe, R. J.; Tomé, C. N.

    2015-05-14

    In-situ straining was used to study deformation behavior of hexagonal close-packed (hcp) metals.Twinning and dislocation motion, both essential to plasticity in hcp materials, were observed.Typically, these processes are characterized post-mortem by examining remnant microstructural features after straining has occurred. By imposing deformation during imaging, direct observation of active deformation mechanisms is possible. This work focuses on straining of structural metals in a transmission electron microscope (TEM), and a recently developed technique that utilizes familiar procedures and equipment to increase ease of experiments. In-situ straining in a TEM presents several advantages over conventional post-mortem characterization, most notably time-resolution of deformation andmore » streamlined identification of active deformation mechanisms. Drawbacks to the technique and applicability to other studies are also addressed. In-situ straining is used to study twin boundary motion in hcp magnesium. A {101¯2} twin was observed during tensile and compressive loading. Twin-dislocation interactions are directly observed. Notably, dislocations are observed to remain mobile, even after multiple interactions with twin boundaries, a result which suggests that Basinki’s dislocation transformation mechanism by twinning is not present in hcp metals. The coupling of in-situ straining with traditional post-mortem characterization yields more detailed information about material behavior during deformation than either technique alone.« less

  17. Transmission Electron Microscope In Situ Straining Technique to Directly Observe Defects and Interfaces During Deformation in Magnesium

    SciTech Connect

    Morrow, Benjamin M.; Cerreta, E. K.; McCabe, R. J.; Tomé, C. N.

    2015-05-14

    In-situ straining was used to study deformation behavior of hexagonal close-packed (hcp) metals.Twinning and dislocation motion, both essential to plasticity in hcp materials, were observed.Typically, these processes are characterized post-mortem by examining remnant microstructural features after straining has occurred. By imposing deformation during imaging, direct observation of active deformation mechanisms is possible. This work focuses on straining of structural metals in a transmission electron microscope (TEM), and a recently developed technique that utilizes familiar procedures and equipment to increase ease of experiments. In-situ straining in a TEM presents several advantages over conventional post-mortem characterization, most notably time-resolution of deformation and streamlined identification of active deformation mechanisms. Drawbacks to the technique and applicability to other studies are also addressed. In-situ straining is used to study twin boundary motion in hcp magnesium. A {101¯2} twin was observed during tensile and compressive loading. Twin-dislocation interactions are directly observed. Notably, dislocations are observed to remain mobile, even after multiple interactions with twin boundaries, a result which suggests that Basinki’s dislocation transformation mechanism by twinning is not present in hcp metals. The coupling of in-situ straining with traditional post-mortem characterization yields more detailed information about material behavior during deformation than either technique alone.

  18. Transmission Electron Microscope In Situ Straining Technique to Directly Observe Defects and Interfaces During Deformation in Magnesium

    NASA Astrophysics Data System (ADS)

    Morrow, B. M.; Cerreta, E. K.; McCabe, R. J.; Tomé, C. N.

    2015-08-01

    In situ straining was used to study deformation behavior of hexagonal close-packed (hcp) metals. Twinning and dislocation motion, both essential to plasticity in hcp materials, were observed. Typically, these processes are characterized postmortem by examining remnant microstructural features after straining has occurred. By imposing deformation during imaging, direct observation of active deformation mechanisms is possible. This work focuses on straining of structural metals in a transmission electron microscope (TEM), and a recently developed technique that utilizes familiar procedures and equipment to increase ease of experiments. In situ straining in a TEM presents several advantages over conventional postmortem characterization, most notably time resolution of deformation and streamlined identification of active deformation mechanisms. Drawbacks to the technique and applicability to other studies are also addressed. In situ straining is used to study twin boundary motion in hcp magnesium. A twin was observed during tensile and compressive loading. Twin-dislocation interactions are directly observed. Notably, dislocations are observed to remain mobile, even after multiple interactions with twin boundaries; this result suggests that Basinki's dislocation transformation mechanism by twinning is not present in hcp metals. The coupling of in situ straining with traditional postmortem characterization yields more detailed information about material behavior during deformation than either technique alone.

  19. Retrieval of Atmospheric Temperature from Airborne Microwave Radiometer Observations

    NASA Astrophysics Data System (ADS)

    Xu, Jian; Schreier, Franz; Kenntner, Mareike; Fix, Andreas; Trautmann, Thomas

    2015-06-01

    Atmospheric temperature is a key geophysical parameter associated with fields such as meteorology, climatology, or photochemistry. There exist several techniques to measure temperature profiles. In the case of microwave remote sensing, the vertical temperature profile can be estimated from thermal emission lines of molecular oxygen. The MTP (Microwave Temperature Profiler) instrument is an airborne radiometer developed at the Jet Propulsion Laboratory (JPL), United States. The instrument passively measures natural thermal emission from oxygen lines at 3 frequencies and at a selection of 10 viewing angles (from near zenith to near nadir). MTP has participated in hundreds of flights, including on DLR’s Falcon and HALO aircrafts. These flights have provided data of the vertical temperature distribution from the troposphere to the lower stratosphere with a good temporal and spatial resolution. In this work, we present temperature retrievals based on the Tikhonov-type regularized nonlinear least squares fitting method. In particular, Jacobians (i.e. temperature derivatives) are evaluated by means of automatic differentiation. The retrieval performance from the MTP measurements is analyzed by using synthetic data. Besides, the vertical sensitivity of the temperature retrieval is studied by weighting functions characterizing the sensitivity of the transmission at different frequencies with respect to changes of altitude levels.

  20. Methane emissions from Alaska in 2012 from CARVE airborne observations

    PubMed Central

    Chang, Rachel Y.-W.; Miller, Charles E.; Dinardo, Steven J.; Karion, Anna; Sweeney, Colm; Daube, Bruce C.; Henderson, John M.; Mountain, Marikate E.; Eluszkiewicz, Janusz; Miller, John B.; Bruhwiler, Lori M. P.; Wofsy, Steven C.

    2014-01-01

    We determined methane (CH4) emissions from Alaska using airborne measurements from the Carbon Arctic Reservoirs Vulnerability Experiment (CARVE). Atmospheric sampling was conducted between May and September 2012 and analyzed using a customized version of the polar weather research and forecast model linked to a Lagrangian particle dispersion model (stochastic time-inverted Lagrangian transport model). We estimated growing season CH4 fluxes of 8 ± 2 mg CH4⋅m−2⋅d−1 averaged over all of Alaska, corresponding to fluxes from wetlands of 56−13+22 mg CH4⋅m−2⋅d−1 if we assumed that wetlands are the only source from the land surface (all uncertainties are 95% confidence intervals from a bootstrapping analysis). Fluxes roughly doubled from May to July, then decreased gradually in August and September. Integrated emissions totaled 2.1 ± 0.5 Tg CH4 for Alaska from May to September 2012, close to the average (2.3; a range of 0.7 to 6 Tg CH4) predicted by various land surface models and inversion analyses for the growing season. Methane emissions from boreal Alaska were larger than from the North Slope; the monthly regional flux estimates showed no evidence of enhanced emissions during early spring or late fall, although these bursts may be more localized in time and space than can be detected by our analysis. These results provide an important baseline to which future studies can be compared. PMID:25385648

  1. Hydrographic properties of separate residual basins of the Aral Sea: in situ observations and intercomparison

    NASA Astrophysics Data System (ADS)

    Izhitskiy, Alexander; Zavialov, Peter; Kurbaniyazov, Abilgazi

    2015-04-01

    Desiccation of the Aral Sea continued intensively throughout the last decade. As reported by NASA and widely commented in mass media, the eastern lobe of the Southern Sea (i.e., the Large Aral Sea) dried up completely in the summer of 2014. Only the western basin of the Large Sea remains there, and the separation of its northernmost portion called Chernyshev Bay is imminent. The northern part of the former Aral Sea known as the Small Aral Sea has separated decades ago and eventually stabilized thanks to a man-made dam trapping all of the Syr Daria discharges in the Small Sea. In addition, the Tschebas Bay, formerly a large bay of the Aral Sea, has evolved into a separate lake with relatively stable boundaries. In this way, the present-day Aral Sea should be considered as a system of separated water bodies with a common origin but different fates and very different physical, chemical, and biological features. In the presented study, we focus on hydrophysical state of the newly individual parts of the former Aral Sea. The comparative investigation is based on field data collected during two surveys of Shirshov Institute of Oceanology to the Aral Sea which took place in the fall season of 2014. In situ measurements including CTD profiling and water sampling were carried in the central western basin of the Large Aral (Aktumsuk area), in the northern extremity of the western Large Aral (Chernyshev bay), in Tschebas Lake, and the western part of the Small Sea (Shevchenko Bay). The analysis of direct observations together with the satellite data allows clarifying main processes and factors determining the physical state of the residual water bodies. According to the results of the in situ observations, three different types of hydrographic structure were documented in the lakes of the former Aral Sea. Salinity of Tschebas Lake water was around 92 g/kg, with the water column fully mixed from surface to bottom. The CTD measurements conducted in the Shevchenko bay of the

  2. Comparing Cirrus Cloud Formation and Evolution Using in Situ Aircraft Observations and a Cloud Resolving Model

    NASA Astrophysics Data System (ADS)

    Diao, M.; Jensen, J. B.; Bryan, G. H.; Morrison, H.; Stern, D. P.

    2014-12-01

    Cirrus clouds, covering ~30% of the Earth, play important roles in Earth's climate and weather. As a major uncertainty in climate models, cirrus clouds' radiative forcing (cooling or warming) is influenced by both the microphysical properties (such as ice crystal concentration and size) and the larger scale structure (such as horizontal and vertical extent). Recent studies (Diao et al. 2013; Diao et al. 2014), based on in situ observations with ~200 m horizontal resolution, showed that the initial conditions of cirrus formation - ice supersaturated regions (ISSRs, where ISS is spatially continuous) - occur mostly at horizontal scales around 1 km, in contrast to the ~100 km scales by previous observations (Gierens et al. 2000). Yet it is still unknown whether current cloud resolving models can capture these small-scale ISSR features. In this work, we compare the observed characteristics of the ice supersaturation (ISS) with an idealized, cloud-resolving simulation of a squall line (Bryan and Morrison, 2012). The model (CM1) was run with 250 m grid spacing using a double-moment microphysics scheme (Morrison et al. 2005). Our comparisons show that the CM1 model has captured the majority of the small-scale ISSRs (~1 km). In addition, the simulated ISSRs are dominated by water vapor horizontal heterogeneities (~90%) as opposed to temperature heterogeneities (~10%). This result is comparable to the observed values of ~88% and ~9%, respectively. However, when comparing the evolution phases of cirrus clouds (clear-sky ISS, nucleation/freezing, growth and sedimentation/sublimation; Diao et al. 2013), the CM1 simulation does not have sufficient amount of ISS in clear-sky and nucleation phases. This disagreement indicates a shortcoming of the idealized model setup. Overall, the observations show more ISS at higher magnitude (up to ~150% of RHi) than CM1 (~up to 130% of RHi). Also the largest ISSRs in the observations are up to ~100 km, compared with those in CM1 of up to ~10

  3. Curiosity in Situ Observations at Kylie, a Preview of the Kimberley Drill Site Geology

    NASA Astrophysics Data System (ADS)

    Edgar, L. A.; Williams, R. M. E.; Rice, M. S.; Stack, K.; Grotzinger, J. P.; Gupta, S.; Rubin, D. M.; Sumner, D. Y.; Lewis, K. W.; Le Deit, L.; Wiens, R. C.

    2014-12-01

    After passing through Dingo Gap, Curiosity turned south and explored the Kylie outcrop on sols 550 to 555. Kylie is topographically higher (by ~10 meters) than the Kimberley located ~300 m to the south, and shares the same succession of geomorphic units identified in satellite images. Thus, in situ observations at Kylie provided context for the subsequent drilling campaign at the Kimberley. Additionally, comparisons of the stratigraphy exposed at Kylie with stratigraphic sections observed at other locations along the traverse (including Darwin, Cooperstown, and Dingo Gap) enable regional correlations and the development of working hypotheses for the former depositional environments. The sedimentary facies exposed at Kylie include pebble-rich conglomerates and sandstones that vary in bedding orientation and stratification. Exposed on the basin walls is a fining upward stratigraphic succession with a basal pebble conglomerate, flat-bedded sandstone, and a resistant, dark-grey massive to crudely stratified sandstone capping facies. The conglomerate facies forms a prominent bench that rims the western side of the basin. ChemCam data indicate that the pebble-rich conglomerates have mafic and felsic elements and appear similar in composition to the conglomerates previously encountered during the mission. Within the basin, the sedimentary deposits appear to drape pre-existing topography. The most voluminous facies has decimeter-thick south-dipping beds of cross-bedded sandstone that correspond to distinct NE-SW trending linear bands in orbital images. In the southern portion of the basin, these south-dipping cross-bedded sandstones are overlain by thin-bedded, sub-meter cross-bedded sandstone and a poorly exposed, scree-covered butte forming facies. The Kylie deposits are consistent with a complex scenario of dominantly fluvial activity, although the nature and magnitude of flows is still being investigated.

  4. In Situ Observations during Chemical Vapor Deposition of Hexagonal Boron Nitride on Polycrystalline Copper

    PubMed Central

    2014-01-01

    Using a combination of complementary in situ X-ray photoelectron spectroscopy and X-ray diffraction, we study the fundamental mechanisms underlying the chemical vapor deposition (CVD) of hexagonal boron nitride (h-BN) on polycrystalline Cu. The nucleation and growth of h-BN layers is found to occur isothermally, i.e., at constant elevated temperature, on the Cu surface during exposure to borazine. A Cu lattice expansion during borazine exposure and B precipitation from Cu upon cooling highlight that B is incorporated into the Cu bulk, i.e., that growth is not just surface-mediated. On this basis we suggest that B is taken up in the Cu catalyst while N is not (by relative amounts), indicating element-specific feeding mechanisms including the bulk of the catalyst. We further show that oxygen intercalation readily occurs under as-grown h-BN during ambient air exposure, as is common in further processing, and that this negatively affects the stability of h-BN on the catalyst. For extended air exposure Cu oxidation is observed, and upon re-heating in vacuum an oxygen-mediated disintegration of the h-BN film via volatile boron oxides occurs. Importantly, this disintegration is catalyst mediated, i.e., occurs at the catalyst/h-BN interface and depends on the level of oxygen fed to this interface. In turn, however, deliberate feeding of oxygen during h-BN deposition can positively affect control over film morphology. We discuss the implications of these observations in the context of corrosion protection and relate them to challenges in process integration and heterostructure CVD. PMID:25673919

  5. In situ observation and analysis of ultrasonic capillary effect in molten aluminium.

    PubMed

    Tzanakis, I; Xu, W W; Eskin, D G; Lee, P D; Kotsovinos, N

    2015-11-01

    An in situ synchrotron radiographic study of a molten Al-10 wt% Cu alloy under the influence of an external ultrasonic field was carried out using the Diamond-Manchester Branchline pink X-ray imaging at the Diamond Light Source in UK. A bespoke test rig was used, consisting of an acoustic transducer with a titanium sonotrode coupled with a PID-controlled resistance furnace. An ultrasonic frequency of 30 kHz, with a peak to peak amplitude at 140 microns, was used, producing a pressure output of 16.9 MPa at the radiation surface of the 1-mm diameter sonotrode. This allowed quantification of not only the cavitation bubble formation and collapse, but there was also evidence of the previously hypothesised ultrasonic capillary effect (UCE), providing the first direct observations of this phenomenon in a molten metallic alloy. This was achieved by quantifying the re-filling of a pre-existing groove in the shape of a tube (which acted as a micro-capillary channel) formed by the oxide envelope of the liquid sample. Analytical solutions of the flow suggest that the filling process, which took place in very small timescales, was related to micro-jetting from the collapsing cavitation bubbles. In addition, a secondary mechanism of liquid penetration through the groove, which is related with the density distribution of the oxides inside the groove, and practically to the filtration of aluminium melt from oxides, was revealed. The observation of the almost instantaneous re-filling of a micro-capillary channel with the metallic melt supports the hypothesised sono-capillary effect in technologically important liquids other than water, like metallic alloys with substantially higher surface tension and density. PMID:26186822

  6. In-situ observations of the April 2014 Mount Everest Avalanche

    NASA Astrophysics Data System (ADS)

    Moore, Kent; Cristofanelli, Paolo; Bonasoni, Paolo; Pietro Verza, Gian; Semple, John

    2016-04-01

    Instrumental records indicate a warming of approximately 0.8oC has occurred in the Everest region since the 1980s that has resulted in a 100-300m rise in the height at which the ground is permanently frozen as well as a retreat and thinning of Everest's glaciers. This period of warming has coincided with Mount Everest becoming an increasingly important destination for both climbers and trekkers. For some time, there have been concerns that this warming and the resultant changes in the region's glaciers may be increasing the risks for both travellers to Mount Everest as well as the indigenous populations who support them. On April 18 2014, an avalanche caused by the collapse of a large serac swept down Mount Everest's Khumbu Ice Fall resulting in the deaths of 16 Sherpa. Although satellite imagery has been used to estimate the size of the serac, in-situ data on the avalanche itself has not been available. Here we show that this event was of a sufficient size as to result in the excitation of a 20 min long 'avalanche wind' that was observed at the Nepal Climate Observatory-Pyramid situated 12 km from Mount Everest. We use these observations to estimate that the winds at Everest Base Camp during this event were of hurricane strength. As a result of the destabilization of the region's glaciers due to the climate change, there are concerns that such events may become more frequent. These results provide the basis for a method to estimate the frequency and severity of avalanches in this region.

  7. Airborne DIAL Ozone and Aerosol Trends Observed at High Latitudes Over North America from February to May 2000

    NASA Technical Reports Server (NTRS)

    Hair, Jonathan W.; Browell, Edward V.; Butler, Carolyn F.; Grant, William B.; DeYoung, Russell J.; Fenn, Marta A.; Brackett, Vince G.; Clayton, Marian B.; Brasseur, Lorraine

    2002-01-01

    Ozone (O3) and aerosol scattering ratio profiles were obtained from airborne lidar measurements on thirty-eight aircraft flights over seven aircraft deployments covering the latitudes of 40 deg.-85 deg.N between 4 February and 23 May 2000 as part of the TOPSE (Tropospheric Ozone Production about the Spring Equinox) field experiment. The remote and in situ O3 measurements were used together to produce a vertically-continuous O3 profile from near the surface to above the tropopause. Ozone, aerosol, and potential vorticity (PV) distributions were used together to identify the presence of pollution plumes and stratospheric intrusions. The number of observed pollution plumes was found to increase into the spring along with a significant increase in aerosol loading. Ozone was found to increase in the middle free troposphere (4-6 km) at high latitudes (60 deg.-85 deg. N) by an average of 4.3 ppbv/mo from about 55 ppbv in early February to over 72 ppbv in mid-May. The average aerosol scattering ratios in the same region increased at an average rate of 0.37/mo from about 0.35 to over 1.7. Ozone and aerosol scattering were highly correlated over entire field experiment. Based on the above results and the observed aircraft in-situ measurements, it was estimated that stratospherically-derived O3 accounted for less than 20% of the observed increase in mid tropospheric O3 at high latitudes. The primary cause of the observed O3 increase was found to be the photochemical production of O3 in pollution plumes.

  8. Quantifying spatial and temporal variability in atmospheric ammonia with in situ and space-based observations--article

    EPA Science Inventory

    Ammonia plays an important role in many biogeochemical processes, yet atmospheric mixing ratios are not well known. Recently, methods have been developed for retrieving NH3 from space-based observations, but they have not been compared to in situ measurements. We have conducted a...

  9. Surface heterogeneity, measurement uncertainty, and the implications for using in-situ observations for model validation studies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In-situ observations are critical for developing, calibrating, and validating the remote sensing-based models used to estimate and predict evapotranspiration (ET) along with the other components of the surface energy budget. Field measurements of the surface energy fluxes are collected using a varie...

  10. The development and evaluation of airborne in situ N2O and CH4 sampling using a quantum cascade laser absorption spectrometer (QCLAS)

    NASA Astrophysics Data System (ADS)

    Pitt, J. R.; Le Breton, M.; Allen, G.; Percival, C. J.; Gallagher, M. W.; Bauguitte, S. J.-B.; O'Shea, S. J.; Muller, J. B. A.; Zahniser, M. S.; Pyle, J.; Palmer, P. I.

    2016-01-01

    Spectroscopic measurements of atmospheric N2O and CH4 mole fractions were made on board the FAAM (Facility for Airborne Atmospheric Measurements) large atmospheric research aircraft. We present details of the mid-infrared quantum cascade laser absorption spectrometer (QCLAS, Aerodyne Research Inc., USA) employed, including its configuration for airborne sampling, and evaluate its performance over 17 flights conducted during summer 2014. Two different methods of correcting for the influence of water vapour on the spectroscopic retrievals are compared and evaluated. A new in-flight calibration procedure to account for the observed sensitivity of the instrument to ambient pressure changes is described, and its impact on instrument performance is assessed. Test flight data linking this sensitivity to changes in cabin pressure are presented. Total 1σ uncertainties of 2.47 ppb for CH4 and 0.54 ppb for N2O are derived. We report a mean difference in 1 Hz CH4 mole fraction of 2.05 ppb (1σ = 5.85 ppb) between in-flight measurements made using the QCLAS and simultaneous measurements using a previously characterised Fast Greenhouse Gas Analyser (FGGA, Los Gatos Research, USA). Finally, a potential case study for the estimation of a regional N2O flux using a mass balance technique is identified, and the method for calculating such an estimate is outlined.

  11. The development and evaluation of airborne in situ N2O and CH4 sampling using a Quantum Cascade Laser Absorption Spectrometer (QCLAS)

    NASA Astrophysics Data System (ADS)

    Pitt, J. R.; Le Breton, M.; Allen, G.; Percival, C. J.; Gallagher, M. W.; Bauguitte, S. J.-B.; O'Shea, S. J.; Muller, J. B. A.; Zahniser, M. S.; Pyle, J.; Palmer, P. I.

    2015-08-01

    Spectroscopic measurements of atmospheric N2O and CH4 mole fractions were made on board the FAAM (Facility for Airborne Atmospheric Measurements) large Atmospheric Research Aircraft. We present details of the mid-IR Aerodyne Research Inc. Quantum Cascade Laser Absorption Spectrometer (QCLAS) employed, including its configuration for airborne sampling, and evaluate its performance over 17 flights conducted during summer 2014. Two different methods of correcting for the influence of water vapour on the spectroscopic retrievals are compared and evaluated. A new in-flight calibration procedure to account for the observed sensitivity of the instrument to ambient pressure changes is described, and its impact on instrument performance is assessed. Test flight data linking this sensitivity to changes in cabin pressure is presented. Total 1σ uncertainties of 1.81 ppb for CH4 and 0.35 ppb for N2O are derived. We report a mean difference in 1 Hz CH4 mole fraction of 2.05 ppb (1σ = 5.85 ppb) between in-flight measurements made using the QCLAS and simultaneous measurements using a previously characterised Los Gatos Research Fast Greenhouse Gas Analyser (FGGA). Finally, a potential case study for the estimation of a regional N2O flux using a mass balance technique is identified, and the method for calculating such an estimate is outlined.

  12. Constraining Annual Water Balance Estimates with Basin-Scale Observations from the Airborne Snow Observatory during the Current Californian Drought

    NASA Astrophysics Data System (ADS)

    Bormann, K.; Painter, T. H.; Marks, D. G.; Hedrick, A. R.; Deems, J. S.; Patterson, V.; McGurk, B. J.

    2015-12-01

    One of the great unknowns in mountain hydrology is how much water is stored within a seasonal snowpack at the basin scale. Quantifying mountain water resources is critical for assisting with water resource management, but has proven elusive due to high spatial and temporal variability of mountain snow cover, complex terrain, accessibility constraints and limited in-situ networks. The Airborne Snow Observatory (ASO, aso.jpl.nasa.gov) uses coupled airborne LiDAR and spectrometer instruments for high resolution snow depth retrievals which are used to derive unprecedented basin-wide estimates of snow water mass (snow water equivalent, SWE). ASO has been operational over key basins in the Sierra Nevada Mountains in California since 2013. Each operational year has been very dry, with precipitation in 2013 at 75% of average, 2014 at 50% of average and 2015 - the lowest snow year on record for the region. With vastly improved estimates of the snowpack water content from ASO, we can now for the first time conduct observation-based mass balance accounting of surface water in snow-dominated basins, and reconcile these estimates with observed reservoir inflows. In this study we use ASO SWE data to constrain mass balance accounting of basin annual water storages to quantify the water contained within the snowpack above the Hetch Hetchy water supply reservoir (Tuolumne River basin, California). The analysis compares and contrasts annual snow water volumes from observed reservoir inflows, snow water volume estimates from ASO, a physically based model that simulates the snowpack from meteorological inputs and a semi-distributed hydrological model. The study provides invaluable insight to the overall volume of water contained within a seasonal snowpack during a severe drought and how these quantities are simulated in our modelling systems. We envisage that this research will be of great interest to snowpack modellers, hydrologists, dam operators and water managers worldwide.

  13. Data assimilation with in situ soil moisture observations: what spatial configuration of the sensor network should be considered?

    NASA Astrophysics Data System (ADS)

    De Vleeschouwer, Niels; Verhoest, Niko E. C.; Pauwels, Valentijn R. N.

    2016-04-01

    Continuously monitoring soil moisture in a permanent in situ network can yield an interesting observation product for hydrological data assimilation. Those in situ observations can be characterised by some major advantages such as a fine temporal resolution, a large vertical extent, the small impact of land cover on the observation error, etc. Because of the typical small integration volume of in situ measurements and the often large spacing between monitoring locations, only a small part of the modelling domain can be directly observed. Therefore a first important question to answer is whether spatially sparse in-situ soil moisture observations contain a sufficient data representativeness to successfully update the largely unobserved spatial extent of a distributed hydrological model. Furthermore, the spatial configuration of the sensors remains unaltered through time. Consequently it is interesting to assess the sensitivity of the spatial configuration of the sensors regarding the data assimilation performance. This allows for answering a second question: is it possible to reduce the number of sensors by optimising the design of the in situ network whilst maintaining the same level of assimilation performance? To bring added value in practice, one should be able to identify optimal network configurations using prior available model input data and/or open loop statistics, i.e. statistics derived from a model run without data assimilation. In this study the meso-scale catchment of the Bellebeek (±100 km²) in Belgium is modelled. The above-mentioned questions are addressed by means of a synthetic data assimilation framework using the ensemble Kalman filter. It can be concluded that the network configuration can indeed have a significant influence on the assimilation performance. Furthermore, preliminary results indicate that certain open loop statistics can be used as a network performance predictor. More in particular, it was examined whether the information

  14. Stratospheric Age Spectra and Mean Ages from In Situ Observations of Carbon Dioxide

    NASA Technical Reports Server (NTRS)

    Andrews, Arlyn E.; Boering, Kristie A.; Daube, Bruce C., Jr.; Wofsy, Steven C.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    In situ observations of CO2 obtained from 1992 through 2000 using the NASA ER-2 aircraft and high-altitude balloons show that seasonal and interannual variations in CO2 mixing ratios propagate from the troposphere into the lower stratosphere via the tropical tropopause, along with the long-term trend due to fossil fuel combustion. These signals spread laterally and vertically, providing detailed quantitative information about the transport history of sampled air. We have used these data to derive age spectra and mean ages that can be compared with results from models of the stratospheric circulation. For an air parcel at a point in the stratosphere, the age spectrum is defined as the probability distribution function for transit times from the tropical tropopause for each fluid element comprising the parcel. The mean age is the average transit time, corresponding to the first moment of the age spectrum. Age spectra have been derived for altitudes below approximately 20 km for the tropics and for northern midlatitudes where there is sufficient data and where the amplitudes of the seasonal and interannual oscillations in CO2 mixing ratios are large enough to be detected. Tropical age spectra are narrow, with seasonal variation indicating faster ascent during northern winter, consistent with a circulation driven by breaking of extratropical waves. The midlatitude CO2 data are consistent with bimodal age spectra, which could result from a subtropical "barrier" to horizontal exchange over a substantial altitude region. Seasonally resolved mean ages are available with nearly pole-to-pole coverage below 20 km and in the tropics and at middle and high northern latitudes up to the maximum altitude reached by the balloons (approximately 30 km). At ER-2 altitudes, steep meridional gradients in mean age are observed in the subtropics. Between 20 and 30 km, midlatitude air is approximately 2 years older than tropical air at the same altitude. The oldest air sampled was in the

  15. Atmospheric OH reactivity in central London: observations, model predictions and estimates of in situ ozone production

    NASA Astrophysics Data System (ADS)

    Whalley, L. K.; Stone, D.; Bandy, B.; Dunmore, R.; Hamilton, J. F.; Hopkins, J.; Lee, J. D.; Lewis, A. C.; Heard, D. E.

    2015-11-01

    -generated intermediates worsened the agreement between modelled and observed OH concentrations (by 41 %) and the magnitude of in situ ozone production calculated from the production of RO2 was significantly lower (60 %). This work highlights that any future ozone abatement strategies should consider the role that biogenic emissions play alongside anthropogenic emissions in influencing London's air quality.

  16. VISIONS: Combined remote sensing and in situ observations of auroral zone ion outflow during a substorm

    NASA Astrophysics Data System (ADS)

    Rowland, D. E.; Clemmons, J. H.; Hecht, J. H.; Lemon, C. L.; Collier, M. R.; Keller, J. W.; Pfaff, R. F.; Klenzing, J.; McLain, J.

    2013-12-01

    The 'first step' in the chain of events that energizes thermal ions from a few tenths of an eV to 10 keV and transports them from the topside ionosphere to high altitudes occurs in the 300-1000 km altitude regime. In this region, various drivers work together to heat and accelerate the ions and push them up the field line. These include Joule heating, soft electron precipitation (driving ambipolar fields), and BBELF and VLF waves. Since the ions need to gain at least several eV to reach the higher altitudes where wave-particle interactions have been observed to form ion conics and beams, the low-altitude region serves as a 'rate limiting step' for the overall process of ion energization and outflow. Major outstanding questions still remain as to the extent and duration of outflow, and the details of the mechanisms that drive it - questions that can only be resolved by studying this critical altitude region. VISIONS (VISualizing Ion Outflow via Neutral atom imaging during a Substorm) was a sounding rocket mission launched Feb 7, 2013, at 0821 UTC from Poker Flat, AK into the expansion phase of an auroral substorm. VISIONS was expressly designed to take advantage of the sounding rocket trajectory (slow motion through the auroral features and vertical profile) and a unique combination of in situ and remote sensing to shed new light on the drivers of low-altitude ion outflow. VISIONS carried five instruments, which together with ground-based instrumentation, measure the relevant parameters for studying ion outflow: 1) a low-energy energetic neutral atom (ENA) imager, MILENA, to remotely sense ion outflow from 50 eV to 3 keV 2) an electrostatic analyzer for electrons from 3 eV - 30 keV 3) an electrostatic analyzer for ions from 1.5 eV - 15 eV 4) a four-channel visible imager (6300, 3914, H-Beta, and 8446) with 90 degree field of view for understanding electron precipitation over a wide area and for comparison with the ENA images 5) a fields and thermal plasma suite that

  17. First joint in situ and global observations of the medium-energy oxygen and hydrogen in the inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Valek, P. W.; Goldstein, J.; Jahn, J.-M.; McComas, D. J.; Spence, H. E.

    2015-09-01

    We present the first simultaneous observations of the in situ ions and global Energetic Neutral Atom (ENA) images of the composition-separated, medium-energy (~1-50 keV) particle populations of the inner magnetosphere. The ENA emissions are mapped into L shell/magnetic local time space based on the exospheric density along the line of sight (LOS). The ENA measurement can then be scaled to determine an average ion flux along a given LOS. The in situ ion flux tends to be larger than the scaled ENAs at the same local time. This indicates that the ion population is more concentrated in the Van Allen Probes orbital plane than distributed along the Two Wide-angle Imaging Neutral-atom Spectrometers LOS. For the large storm of 14 November 2012, we observe that the concentration of O (in situ ions and ENAs) increases during the storm's main phase with a relatively larger increase than H. The ratio of the O+/H+ can be measured both from the in situ observations and from the ENA images. During the main phase, this O+/H+ increase is initially seen near midnight, but when the storm reaches its peak value the O+/H+ ratio increases across all local times, with the largest at dusk and dawn.

  18. On the structure of the extra-tropical transition layer from in-situ observations

    NASA Astrophysics Data System (ADS)

    Pisso, I.; Law, K. S.; Fierli, F.; Haynes, P. H.; Hoor, P.; Palazzi, E.; Ravegnani, F.; Viciani, S.

    2012-10-01

    In-situ observations of atmospheric tracers from multiple measurement campaigns over the period 1994-2007 were combined to investigate the Extra-tropical Transition Layer (ExTL) region and the properties of large scale meridional transport. We used potential temperature, equivalent latitude and distance relative to the local dynamical tropopause as vertical coordinates to highlight the behaviour of trace gases in the tropopause region. Vertical coordinates based on constant PV surfaces allowed us to relate the dynamical definition of the tropopause with trace gases distributions and vertical gradients and hence analyse its latitudinal dependence and seasonal variability. Analysis of the available data provides a working definition of the upper limit of the ExTL based on the upper limit of the region of high vertical CO gradient in PV relative coordinates. A secondary local maximum in vertical O3 gradient can be used a proxy for the lower limit, although it is less clearly defined than that of CO. The sloping isopleths of CO and O3 mixing ratios and the CO mixing ratio gradient are consistent with isopleths in purely dynamical diagnostics such as χ30 d, the proportion of air masses in contact with the PBL within one month and underline the differences between the PV based and chemical tropopauses. The use of tropopause relative coordinates allows different seasons to be analysed together to produce climatological means. The weak dependence of dynamical diagnostics of transport on the absolute values of tracer concentrations makes them a suitable process-oriented tool to evaluate global chemical models and make Lagrangian comparisons.

  19. Comparison of CME/Shock Propagation Models with Heliospheric Imaging and In Situ Observations

    NASA Astrophysics Data System (ADS)

    Zhao, Xinhua; Liu, Ying D.; Inhester, Bernd; Feng, Xueshang; Wiegelmann, Thomas; Lu, Lei

    2016-10-01

    The prediction of the arrival time for fast coronal mass ejections (CMEs) and their associated shocks is highly desirable in space weather studies. In this paper, we use two shock propagation models, i.e., Data Guided Shock Time Of Arrival (DGSTOA) and Data Guided Shock Propagation Model (DGSPM), to predict the kinematical evolution of interplanetary shocks associated with fast CMEs. DGSTOA is based on the similarity theory of shock waves in the solar wind reference frame, and DGSPM is based on the non-similarity theory in the stationary reference frame. The inputs are the kinematics of the CME front at the maximum speed moment obtained from the geometric triangulation method applied to STEREO imaging observations together with the Harmonic Mean approximation. The outputs provide the subsequent propagation of the associated shock. We apply these models to the CMEs on 2012 January 19, January 23, and March 7. We find that the shock models predict reasonably well the shock’s propagation after the impulsive acceleration. The shock’s arrival time and local propagation speed at Earth predicted by these models are consistent with in situ measurements of WIND. We also employ the Drag-Based Model (DBM) as a comparison, and find that it predicts a steeper deceleration than the shock models after the rapid deceleration phase. The predictions of DBM at 1 au agree with the following ICME or sheath structure, not the preceding shock. These results demonstrate the applicability of the shock models used here for future arrival time prediction of interplanetary shocks associated with fast CMEs.

  20. Observation and Analysis of In Situ Carbonaceous Matter in Naklha. Part 2

    NASA Technical Reports Server (NTRS)

    Gibson, E. K., Jr.; Clemett, S. J.; Thomas-Kerpta, K. L.; McKay, D. S.; Wentworth, S. J.; Robert, F.; Verchovsky, A. B.; Wright, I. P.; Pillinger, C. T.; Rice, T.; VanLeer, B.

    2006-01-01

    The search for indigenous carbon components on Mars has been a challenge. The first attempt was the Viking GC-MS in situ experiment which gave inconclusive results at two sites on Mars [1]. After the discovery that the SNC meteorites were from Mars [2], [3-5] reported C isotopic compositional information which suggested a reduced C component present in the martian meteorites. [6 & 7] reported the presence of reduced C components (i.e., polycyclic aromatic hydrocarbons) associated with the carbonate globules in ALH84001. Jull et al. [8] noted in Nakhla there was an acid insoluble C component present with more than 75% of its C lacking any C-14, which is modern-day carbon. This C fraction was believed to be either indigenous martian or ancient meteoritic carbon. Fisk et al. [9, 10] have shown textural evidence along with C-enriched areas within fractures in Nakhla and ALH84001. To further understand the nature of possible indigenous reduced C components, we have carried out a variety of measurements on martian meteorites. For this presentation we will discuss only the Nakhla results. Interior samples from the Nakhla SNC meteorite, recently made available by the British Museum of Natural History, were analyzed. Petrographic examination [11, McKay et al., this volume] of Nakhla showed evidence of fractures (approx.0.5 micron wide) filled with dark brown to black dendritic material [Fig. 1] with characteristics similar to those observed by [10]. Iddingsite is also present along fractures in olivine. Fracture filling and dendritic material was examined by SEM-EDX, TEM-EDX, Focused Electron Beam microscopy, Laser Raman Spectroscopy, Nano-SIMS Ion Micro-probe, and Stepped-Combustion Static Mass Spectrometry.

  1. Hydration effects on gypsum dissolution revealed by in situ nanoscale atomic force microscopy observations

    NASA Astrophysics Data System (ADS)

    Burgos-Cara, A.; Putnis, C. V.; Rodriguez-Navarro, C.; Ruiz-Agudo, E.

    2016-04-01

    Recent work has suggested that the rates of mineral dissolution in aqueous solutions are dependent on the kinetics of dehydration of the ions building the crystal. Dehydration kinetics will be ultimately determined by the competition between ion-water and water-water interactions, which can be significantly modified by the presence of background ions in solution. At low ionic strength, the effect of electrolytes on ion-water (electrostatic) interactions will dominate (Kowacz et al., 2007). By performing macroscopic and in situ, microscopic (atomic force microscopy) dissolution experiments, the effect of background electrolytes on the dissolution kinetics of gypsum (CaSO4·2H2O) {0 1 0} cleavage surfaces is tested at constant, low ionic strength (IS = 0.05) and undersaturation (saturation index, SI = -0.045). Dissolution rates are systematically lower in the presence of 1:1 background electrolytes than in an electrolyte-free solution, regardless of the nature of the electrolyte tested. We hypothesize that stabilization of the hydration shell of calcium by the presence of background ions can explain this result, based on the observed correlations in dissolution rates with the ionic surface tension increment of the background ion in solution. Stabilization of the cation hydration shell should favor dissolution. However, in the case of strongly hydrated ions such as Ca2+, this has a direct entropic effect that reduces the overall ΔG of the system, so that dissolution is energetically less favorable. Overall, these results provide new evidence that supports cation dehydration being the rate-controlling step for gypsum dissolution, as proposed for other minerals such as barite, dolomite and calcite.

  2. A High-Precision, Fast-Response Airborne CO2 Analyzer for In Situ Sampling From the Surface to the Middle Stratosphere

    NASA Technical Reports Server (NTRS)

    Daube, B. C., Jr.; Boering, K. A.; Andrews, Arlyn E.; Wofsy, S. C.

    2001-01-01

    Two in situ CO2 analyzers have been developed for deployment on the NASA ER-2 aircraft and on stratospheric balloons. The ER-2 instrument has had more than 150 flights during 21 deployments from 1992 to 2000, resulting in a dataset with nearly pole-to-pole coverage that includes data from all seasons in both hemispheres except austral summer. In-flight calibrations show that the typical long-term (i.e. flight-to-flight) precision of the instruments is better than plus or minus 0.1 ppmv. The flight standards are traceable to standards held by the Scripps Institute of Oceanography and the National Oceanic and Atmospheric Administration's Climate Monitoring and Diagnostics Laboratory. The balloon instrument has had 8 balloon flights since September 1996, providing the first in situ observations of CO2 above approx. 21 km. In addition, the balloon instrument has been flown onboard a Cessna Citation II aircraft for sampling between the surface and 10 km. In this paper, the instrumentation and calibration procedures for both instruments are described in detail. An intercomparison of the two instruments during the Photochemistry of Ozone Loss in the Arctic Region In Summer (POLARIS) project showed that, on average, the instruments agreed to within 0.05 ppmv.

  3. Spatio-Temporal Variability of Atmospheric CO2 as Observed from In-Situ Measurements over North America during NASA Field Campaigns (2004-2008)

    NASA Technical Reports Server (NTRS)

    Choi, Yonghoon; Vay, Stephanie A.; Woo, Jung-Hun; Choi, Kichul; Diskin, Glenn S.; Sachse, G. W.; Vadrevu, Krishna P.; Czech, E.

    2009-01-01

    Regional-scale measurements were made over the eastern United States (Intercontinental Chemical Transport Experiment - North America (INTEX-NA), summer 2004); Mexico (Megacity Initiative: Local and Global Research Observations (MILAGRO), March 2006); the eastern North Pacific and Alaska (INTEX-B May 2006); and the Canadian Arctic (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS), spring and summer 2008). For these field campaigns, instrumentation for the in situ measurement of CO2 was integrated on the NASA DC-8 research aircraft providing high-resolution (1 second) data traceable to the WMO CO2 mole fraction scale. These observations provide unique and definitive data sets via their intermediate-scale coverage and frequent vertical profiles (0.1 - 12 km) for examining the variability CO2 exhibits above the Earth s surface. A bottom-up anthropogenic CO2 emissions inventory (1deg 1deg) and processing methodology has also been developed for North America in support of these airborne science missions. In this presentation, the spatio-temporal distributions of CO2 and CO column values derived from the campaign measurements will be examined in conjunction with the emissions inventory and transport histories to aid in the interpretation of the CO2 observations.

  4. Atmospheric OH reactivity in central London: observations, model predictions and estimates of in situ ozone production

    NASA Astrophysics Data System (ADS)

    Whalley, Lisa K.; Stone, Daniel; Bandy, Brian; Dunmore, Rachel; Hamilton, Jacqueline F.; Hopkins, James; Lee, James D.; Lewis, Alastair C.; Heard, Dwayne E.

    2016-02-01

    9) (particularly α-pinene and limonene) and model-generated intermediates increases the modelled OH concentrations by 41 %, and the magnitude of in situ ozone production calculated from the production of RO2 was significantly lower (60 %). This work highlights that any future ozone abatement strategies should consider the role that biogenic emissions play alongside anthropogenic emissions in influencing London's air quality.

  5. Remote and In Situ Observations of an Unusual Earth-Directed Coronal Mass Ejection from Multiple Viewpoints

    NASA Technical Reports Server (NTRS)

    Nieves-Chinchilla, T.; Colaninno, R.; Vourlidas, A.; Szabo, A.; Lepping, R. P.; Boardsen, S. A.; Anderson, B. J.; Korth, H.

    2012-01-01

    During June 16-21, 2010, an Earth-directed Coronal Mass Ejection (CME) event was observed by instruments onboard STEREO, SOHO, MESSENGER and Wind. This event was the first direct detection of a rotating CME in the middle and outer corona. Here, we carry out a comprehensive analysis of the evolution of the CME in the interplanetary medium comparing in-situ and remote observations, with analytical models and three-dimensional reconstructions. In particular, we investigate the parallel and perpendicular cross section expansion of the CME from the corona through the heliosphere up to 1 AU. We use height-time measurements and the Gradual Cylindrical Shell (GCS) technique to model the imaging observations, remove the projection effects, and derive the 3-dimensional extent of the event. Then, we compare the results with in-situ analytical Magnetic Cloud (MC) models, and with geometrical predictions from past works. We nd that the parallel (along the propagation plane) cross section expansion agrees well with the in-situ model and with the Bothmer & Schwenn [1998] empirical relationship based on in-situ observations between 0.3 and 1 AU. Our results effectively extend this empirical relationship to about 5 solar radii. The expansion of the perpendicular diameter agrees very well with the in-situ results at MESSENGER ( 0:5 AU) but not at 1 AU. We also find a slightly different, from Bothmer & Schwenn [1998], empirical relationship for the perpendicular expansion. More importantly, we find no evidence that the CME undergoes a significant latitudinal over-expansion as it is commonly assumed

  6. Airborne DOAS observations of tropospheric NO2 using an UltraLight Trike and flux calculation

    NASA Astrophysics Data System (ADS)

    Constantin, Daniel-Eduard; Voiculescu, Mirela; Merlaud, Alexis; Dragomir, Carmelia; Georgescu, Lucian; Hendrick, Francois; Van Roozendael, Michel

    2016-04-01

    In this paper we present airborne DOAS observations of tropospheric NO2 using an Ultralight Trike (ULT) and associated flux calculation. The instrument onboard the ULT was developed for measuring the tropospheric NO2 Vertical Column Density (VCD). Measurements were performed for several days during 2011-2014, in a region SE of Romania, over the cities of Galati (45.43°N, 28.03°E) and Braila (45.26°N, 27.95°E). Measurements of the NO2 column in the same area were performed using car-DOAS observations. The correlation between the tropospheric NO2 VCD from airborne and mobile ground-based DOAS observations was used to validate the airborne observations. A specific AMF for each case was calculated using the radiative transfer model (RTM) UVspec/DISORT. We present also a comparison between SCDstrato derived from DOMINO (Dutch OMI NO2) and the SCDstrato obtained from ground and airborne measurements. Due to the mobility and flexibility of the ULT flights, this aerial platform provides a promising tool for satellite validation, especially for space observations by high resolution sensors such as the future TROPOMI instrument. A key added value of the ULT-DOAS, illustrated in this work, is the capacity to investigate the spatial variability of NO2 inside the horizontal extent of satellite pixels, e.g. above plant exhaust plumes.

  7. The effect of electrolytes on dolomite dissolution: nanoscale observations using in situ Atomic Force Microscopy

    NASA Astrophysics Data System (ADS)

    Urosevic, Maja; Ruiz-Agudo, Encarnacion; Putnis, Christine V.; Cardell, Carolina; Rodriguez-Navarro, Carlos; Putnis, Andrew

    2010-05-01

    carbonate rocks, both in the natural environment, as well as in stone buildings and statuary, where the amount of solutes in pore waters is significant and can vary depending on evaporation and condensation phenomena. References Higgins, S.R.; Hu, X. Self-limiting growth on dolomite: Experimental observations with in situ atomic force microscopy. Geochimica et Cosmochimica Acta, 2005, 69 (8), 2085-2094. Morse, J.W.; Arvidson, R.S. The dissolution kinetics of major sedimentary carbonate minerals. Earth-Science Reviews, 2002, 58, 51-84. Ruiz-Agudo, E.; Kowacz, M.; Putnis, C.V.; Putnis, A. The role of background electrolytes on the kinetics and mechanism of calcite dissolution. Geochimica et Cosmochimica Acta, 2010, 74, 1256-1267.

  8. RECONSTRUCTING CORONAL MASS EJECTIONS WITH COORDINATED IMAGING AND IN SITU OBSERVATIONS: GLOBAL STRUCTURE, KINEMATICS, AND IMPLICATIONS FOR SPACE WEATHER FORECASTING

    SciTech Connect

    Liu Ying; Luhmann, Janet G.; Lin, Robert P.; Bale, Stuart D.; Thernisien, Arnaud; Vourlidas, Angelos; Davies, Jackie A.

    2010-10-20

    We reconstruct the global structure and kinematics of coronal mass ejections (CMEs) using coordinated imaging and in situ observations from multiple vantage points. A forward modeling technique, which assumes a rope-like morphology for CMEs, is used to determine the global structure (including orientation and propagation direction) from coronagraph observations. We reconstruct the corresponding structure from in situ measurements at 1 AU with the Grad-Shafranov method, which gives the flux-rope orientation, cross section, and a rough knowledge of the propagation direction. CME kinematics (propagation direction and radial distance) during the transit from the Sun to 1 AU are studied with a geometric triangulation technique, which provides an unambiguous association between solar observations and in situ signatures; a track fitting approach is invoked when data are available from only one spacecraft. We show how the results obtained from imaging and in situ data can be compared by applying these methods to the 2007 November 14-16 and 2008 December 12 CMEs. This merged imaging and in situ study shows important consequences and implications for CME research as well as space weather forecasting: (1) CME propagation directions can be determined to a relatively good precision as shown by the consistency between different methods; (2) the geometric triangulation technique shows a promising capability to link solar observations with corresponding in situ signatures at 1 AU and to predict CME arrival at the Earth; (3) the flux rope within CMEs, which has the most hazardous southward magnetic field, cannot be imaged at large distances due to expansion; (4) the flux-rope orientation derived from in situ measurements at 1 AU may have a large deviation from that determined by coronagraph image modeling; and (5) we find, for the first time, that CMEs undergo a westward migration with respect to the Sun-Earth line at their acceleration phase, which we suggest is a universal

  9. New insights into the diurnal variability of animal NH3 emissions using in-situ, satellite and aloft observations

    NASA Astrophysics Data System (ADS)

    Bash, J. O.; Henze, D. K.; Zhu, L.; Jeong, G.; Walker, J. T.; Nowak, J. B.; Neuman, J. A.; Cady-Pereira, K. E.; Shephard, M. W.; Luo, M.; Pinder, R. W.

    2013-12-01

    Ammonia (NH3) is the primary atmospheric base and an important precursor for inorganic particulate matter. NH3 deposition contributes to surface water eutrophication, soil acidification and decline in species biodiversity. Despite its importance in atmospheric chemistry and the nitrogen biogeochemical cycle, the magnitude and temporal dynamics of NH3 emissions remain uncertain in regional and global scale models. This uncertainty stems from the lack of routine ambient NH3 observations and the complexity of NH3 emission sources. We will combine satellite, in-situ, and aircraft observations with model sensitivities to develop and evaluate process based improvements in NH3 emissions from animal production activities. First, we will show that initial model evaluations of ambient NH3 estimates using TES satellite and in-situ Carolina Ammonia Monitoring Network (CAMNet) observations paired in space and time indicated that the Community Multi-scale Air Quality (CMAQ) and GEOS-Chem overestimated CAMNet NH3 observations but underestimated TES observations. An evaluation of the differences in the timing of the measurement techniques indicated that the model errors are due to the dynamics of the temporal NH3 emissions, predominately from animal production. This was confirmed qualitatively using hourly in-situ NH3 observations. Then, a mechanistic NH3 animal emissions conceptual model was developed and implemented for use in both CMAQ and GEOS-Chem models. Finally, we will present improvements in model evaluations of gaseous NH3, NO3 aerosol concentrations and NH4 wet deposition against network, TES satellite and aircraft observations.

  10. Bimodal distribution of free tropospheric ozone over the tropical western Pacific revealed by airborne observations

    NASA Astrophysics Data System (ADS)

    Pan, L. L.; Honomichl, S. B.; Randel, W. J.; Apel, E. C.; Atlas, E. L.; Beaton, S. P.; Bresch, J. F.; Hornbrook, R.; Kinnison, D. E.; Lamarque, J.-F.; Saiz-Lopez, A.; Salawitch, R. J.; Weinheimer, A. J.

    2015-09-01

    A recent airborne field campaign over the remote western Pacific obtained the first intensive in situ ozone sampling over the warm pool region from oceanic surface to 15 km altitude (near 360 K potential temperature level). The new data set quantifies ozone in the tropical tropopause layer under significant influence of convective outflow. The analysis further reveals a bimodal distribution of free tropospheric ozone mixing ratio. A primary mode, narrowly distributed around 20 ppbv, dominates the troposphere from the surface to 15 km. A secondary mode, broadly distributed with a 60 ppbv modal value, is prominent between 3 and 8 km (320 K to 340 K potential temperature levels). The latter mode occurs as persistent layers of ozone-rich drier air and is characterized by relative humidity under 45%. Possible controlling mechanisms are discussed. These findings provide new insight into the physical interpretation of the "S"-shaped mean ozone profiles in the tropics.

  11. Multi-wavelength Airborne High Spectral Resolution Lidar Observations of Aerosol Above Clouds in California during DISCOVER-AQ

    NASA Astrophysics Data System (ADS)

    Hostetler, C. A.; Burton, S. P.; Ferrare, R. A.; Rogers, R. R.; Mueller, D.; Chemyakin, E.; Cook, A. L.; Harper, D. B.; Ziemba, L. D.; Beyersdorf, A. J.; Anderson, B. E.

    2013-12-01

    Accurately representing the vertical profile of aerosols is important for determining their radiative impact, which is still one of the biggest uncertainties in climate forcing. Aerosol radiative forcing can be either positive or negative depending on aerosol absorption properties and underlying albedo. Therefore, accurately characterizing the vertical distribution of aerosols, and specifically aerosols above clouds, is vital to understanding climate change. Unlike passive sensors, airborne lidar has the capability to make vertically resolved aerosol measurements of aerosols above and between clouds. Recently, NASA Langley Research Center has built and deployed the world's first airborne multi-wavelength High Spectral Resolution Lidar, HSRL-2. The HSRL-2 instrument employs the HSRL technique to measure extinction at both 355 nm and 532 nm and also measures aerosol depolarization and backscatter at 355 nm, 532 nm and 1064 nm. Additional HSRL-2 data products include aerosol type and range-resolved aerosol microphysical parameters (e.g., effective radius, number concentration, and single scattering albedo). HSRL-2 was deployed in the San Joaquin Valley, California, from January 16 to February 6, 2013, on the DISCOVER-AQ field campaign (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality). On February 6, the observation region was mostly cloudy, and HSRL-2 saw two distinct aerosol layers above the clouds. One layer was aged boundary-layer pollution located just above cloud top at approximately 1.5 km above sea level. An aged smoke layer was also observed over land and over the ocean at altitudes 4-7 km ASL. In this study, we will show HSRL-2 products for these cases, and compare them with airborne in situ measurements of the 1.5-km layer from a coincident flight of the NASA P3B. We will also compare and contrast the HSRL-2 measurements of these two aerosol layers with each other and the clear-air boundary

  12. Characterizing supraglacial meltwater channel hydraulics on the Greenland Ice Sheet from in situ observations

    USGS Publications Warehouse

    Gleason, Colin J.; Smith, Laurence C.; Chu, Vena W.; Legleiter, Carl; Pitcher, Lincoln H.; Overstreet, Brandon T.; Rennermalm, Asa K.; Forster, Richard R.; Yang, Kang

    2016-01-01

    Supraglacial rivers on the Greenland ice sheet (GrIS) transport large volumes of surface meltwater toward the ocean, yet have received relatively little direct research. This study presents field observations of channel width, depth, velocity, and water surface slope for nine supraglacial channels on the southwestern GrIS collected between 23 July and 20 August, 2012. Field sites are located up to 74 km inland and span 494-1485 m elevation, and contain measured discharges larger than any previous in situ study: from 0.006 to 23.12 m3/s in channels 0.20 to 20.62 m wide. All channels were deeply incised with near vertical banks, and hydraulic geometry results indicate that supraglacial channels primarily accommodate greater discharges by increasing velocity. Smaller streams had steeper water surface slopes (0.74-8.83%) than typical in terrestrial settings, yielding correspondingly high velocities (0.40-2.60 m/s) and Froude numbers (0.45-3.11) with supercritical flow observed in 54% of measurements. Derived Manning's n values were larger and more variable than anticipated from channels of uniform substrate, ranging from 0.009 to 0.154 with a mean value of 0.035 +/- 0.027 despite the absence of sediment, debris, or other roughness elements. Ubiquitous micro-depressions in shallow sections of the channel bed may explain some of these roughness values. However, we find that other, unobserved sources of flow resistance likely contributed to these elevated n values: future work should explicitly consider additional sources of flow resistance beyond bed roughness in supraglacial channels. We conclude that hydraulic modelling for these channels must allow for both sub- and supercritical flow, and most importantly must refrain from assuming that all ice-substrate channels exhibit similar hydraulic behavior, especially for Froude numbers and Manning's n. Finally, this study highlights that further theoretical and empirical work on supraglacial channel hydraulics is

  13. Evaluation of Mixed-Phase Microphysics Within Winter Storms Using Field Data and In Situ Observations

    NASA Technical Reports Server (NTRS)

    Colle, Brian A.; Molthan, Andrew; Yu, Ruyi; Nesbitt, Steven

    2014-01-01

    Snow prediction within models is sensitive to the snow densities, habits, and degree of riming within the BMPs. Improving these BMPs is a crucial step toward improving both weather forecasting and climate predictions. Several microphysical schemes in the Weather Research and Forecasting (WRF) model down to 1.33-km grid spacing are evaluated using aircraft, radar, and ground in situ data from the Global Precipitation Mission Cold-season Precipitation Experiment (GCPEx) experiment over southern Ontario, as well as a few years (12 winter storms) of surface measurements of riming, crystal habit, snow density, and radar measurements at Stony Brook, NY (SBNY on north shore of Long Island) during the 2009-2012 winter seasons. Surface microphysical measurements at SBNY were taken every 15 to 30 minutes using a stereo microscope and camera, and snow depth and snow density were also recorded. During these storms, a vertically-pointing Ku band radar was used to observe the vertical evolution of reflectivity and Doppler vertical velocities. The GCPex presentation will focus on verification using aircraft spirals through warm frontal snow band event on 18 February 2012. All the BMPs realistically simulated the structure of the band and the vertical distribution of snow/ice aloft, except the SBU-YLIN overpredicted slightly and Thompson (THOM) underpredicted somewhat. The Morrison (MORR) scheme produced the best slope size distribution for snow, while the Stony Brook (SBU) underpredicted and the THOM slightly overpredicted. Those schemes that have the slope intercept a function of temperature (SBU and WSM6) tended to perform better for that parameter than others, especially the fixed intercept in Goddard. Overall, the spread among BMPs was smaller than in other studies, likely because there was limited riming with the band. For the 15 cases at SBNY, which include moderate and heavy riming events, the non-spherical snow assumption (THOM and SBU-YLIN) simulated a more realistic

  14. Dissolved methane profiles in marine sediments observed in situ differ greatly from analyses of recovered cores

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Brewer, P. G.; Hester, K.; Ussler, W.; Walz, P. M.; Peltzer, E. T.; Ripmeester, J.

    2009-12-01

    The flux of dissolved methane through continental margin sediments is of importance in marine geochemistry due to its role in massive hydrate formation with enigmatic climate consequences, and for the huge and complex microbial assemblage it supports. Yet the actual dissolved methane concentration driving this flux is poorly known since strong degassing during sample recovery from depth is commonplace. Thus, pore water analyses from high CH4 environments typically show values clustered around the one-atmosphere equilibrium value of 1-2 mM, erasing the original pore water profile and frustrating model calculations. We show that accurate measurement of pore water profiles of dissolved CH4, SO4, and H2S can be made rapidly in situ using a Raman-based probe. While Raman spectra were formerly believed to yield only qualitative data we show that by using a peak area ratio technique to known H2O bands and a form of Beer’s Law quantitative data may be readily obtained. Results from Hydrate Ridge, Oregon clearly show coherent profiles of all three species in this high flux environment, and while in situ Raman and conventional analyses of SO4 in recovered cores agree well, very large differences in CH4 are found. The in situ CH4 results show up to 35 mM in the upper 30cm of seafloor sediments and are inversely correlated with SO4. This is below the methane hydrate saturation value, yet disturbing the sediments clearly released hydrate fragments suggesting that true saturation values may exist only in the hydrate molecular boundary layer, and that lower values may typically characterize the bulk pore fluid of hydrate-hosting sediments. The in situ Raman measurement protocols developed take only a few minutes. Profiles obtained in situ showed minimal fluorescence while pore water samples from recovered cores quickly developed strong fluorescence making laboratory analyses using Raman spectroscopy challenging and raising questions over the reaction sequence responsible for

  15. In Situ Observations and Sampling of Volcanic Emissions with Unmanned Aircraft: A NASA/UCR Case Study at Turrialba Volcano, Costa Rica

    NASA Technical Reports Server (NTRS)

    Pieri, David; Diaz, Jorge Andres; Bland, Geoffrey; Fladeland, Matthew; Madrigal, Yetty; Corrales, Ernesto; Alan, Alfredo; Alegria, Oscar; Realmuto, Vincent; Miles, Ted

    2011-01-01

    Burgeoning new technology in the design and development of robotic aircraft-unmanned aerial vehicles (UAVs)-presents unprecedented opportunities for the volcanology community to observe, measure, and sample eruption plumes and drifting volcanic clouds in situ. While manned aircraft can sample dilute parts of such emissions, demonstrated hazards to air breathing, and most particularly turbine, engines preclude penetration of the zones of highest ash concentrations. Such areas within plumes are often of highest interest with respect to boundary conditions of applicable mass-loading retrieval models, as well as Lagrangian, Eulerian, and hybrid transport models used by hazard responders to predict plume trajectories, particularly in the context of airborne hazards. Before the 2010 Ejyafyallajokull eruption in Iceland, ICAO zero-ash-tolerance rules were typically followed, particularly for relatively uncrowded Pacific Rim airspace, and over North and South America, where often diversion of aircraft around ash plumes and clouds was practical. The 2010 eruption in Iceland radically changed the paradigm, in that critical airspace over continental Europe and the United Kingdom were summarily shut by local civil aviation authorities and EURO CONTROL. A strong desire emerged for better real-time knowledge of ash cloud characteristics, particularly ash concentrations, and especially for validation of orbital multispectral imaging. UAV platforms appear to provide a viable adjunct, if not a primary source, of such in situ data for volcanic plumes and drifting volcanic clouds from explosive eruptions, with prompt and comprehensive application to aviation safety and to the basic science of volcanology. Current work is underway in Costa Rica at Turrialba volcano by the authors, with the goal of developing and testing new small, economical UAV platforms, with miniaturized instrument payloads, within a volcanic plume. We are underway with bi-monthly deployments of tethered SO2-sondes

  16. Initial Comparisons of In-Situ, Model, and Remotely-Sensed NO2 Observations During DISCOVER-AQ

    NASA Astrophysics Data System (ADS)

    Pickering, K. E.; Crawford, J. H.; Flynn, C.; Follette-Cook, M. B.; Krotkov, N. A.; Herman, J. R.; Janz, S. J.; Weinheimer, A. J.; Lee, P.

    2011-12-01

    The first deployment of the Earth Venture -1 DISCOVER-AQ (Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality) project was conducted during July 2011 in the Baltimore-Washington region. Two aircraft (a P-3B for in-situ sampling and a King Air for remote sensing) were used along with an extensive array of surface-based, in-situ, and remote sensing instrumentation. Fourteen flight days were accomplished by both aircraft and over 250 profiles of trace gases and aerosols were performed by the P-3B over surface air quality monitoring stations, which were specially outfitted with Pandora UV/Vis spectrometers recording NO2 columns. The P-3B instrument suite included in-situ NO2 observations. The King Air flew the ACAM UV/Vis spectrometer, providing NO2 column amounts from approximately 8 km to the surface. This combination of observations allows linkage of surface NO2 with its vertical distribution, with remotely-sensed column amounts observed from the surface Pandoras , the ACAM instrument, and with satellite observations from Aura/OMI. Tropospheric NO2 columns from the Pandoras were estimated by subtracting the stratospheric component derived by the OMI NO2 algorithm from the total columns observed by these surface-based spectrometers. In addition, forecasts of NO2 from a NOAA experimental version of the CMAQ regional air quality model were made available to DISCOVER-AQ. A preliminary comparison of tropospheric column NO2 densities from the integration of in-situ P-3B observations, those derived from the Pandoras and ACAM, from the new Goddard OMI tropospheric NO2 algorithm, and from CMAQ will be presented. Interpretation will be provided for differences that are noted.

  17. Vertical Profiles of Light-Absorbing Aerosol: A Combination of In-situ and AERONET Observations during NASA DISCOVER-AQ

    NASA Astrophysics Data System (ADS)

    Ziemba, L. D.; Beyersdorf, A. J.; Chen, G.; Corr, C.; Crumeyrolle, S.; Giles, D. M.; Holben, B. N.; Hudgins, C.; Martin, R.; Moore, R.; Shook, M.; Thornhill, K. L., II; Winstead, E.; Anderson, B. E.

    2014-12-01

    Understanding the vertical profile of atmospheric aerosols plays a vital role in utilizing spaceborne, column-integrated satellite observations. The properties and distribution of light-absorbing aerosol are particularly uncertain despite significant air quality and climate ramifications. Advanced retrieval algorithms are able to derive complex aerosol properties (e.g., wavelength-dependent absorption coefficient and single scattering albedo) from remote-sensing measurements, but quantitative relationships to surface conditions remain a challenge. Highly systematic atmospheric profiling during four unique deployments for the NASA DISCOVER-AQ project (Baltimore, MD, 2011; San Joaquin Valley, CA, 2013; Houston, TX, 2013; Denver, CO, 2014) allow statistical assessment of spatial, temporal, and source-related variability for light-absorbing aerosol properties in these distinct regions. In-situ sampling in conjunction with a dense network of AERONET sensors also allows evaluation of the sensitivity, limitations, and advantages of remote-sensing data products over a wide range of conditions. In-situ aerosol and gas-phase observations were made during DISCOVER-AQ aboard the NASA P-3B aircraft. Aerosol absorption coefficients were measured by a Particle Soot Absorption Photometer (PSAP). Approximately 200 profiles for each of the four deployments were obtained, from the surface (25-300m altitude) to 5 km, and are used to calculate absorption aerosol optical depths (AAODs). These are quantitatively compared to AAOD derived from AERONET Level 1.5 retrievals to 1) explore discrepancies between measurements, 2) quantify the fraction of AAOD that exists directly at the surface and is often missed by airborne sampling, and 3) evaluate the potential for deriving ground-level black carbon (BC) concentrations for air quality prediction. Aerosol size distributions are used to assess absorption contributions from mineral dust, both at the surface and aloft. SP2 (Single Particle Soot

  18. Extinction coefficients from lidar observations in ice clouds compared to in-situ measurements from the Cloud Integrating Nephelometer during CRYSTAL-FACE

    NASA Technical Reports Server (NTRS)

    Noel, Vincent; Winker, D. M.; Garrett, T. J.; McGill, M.

    2005-01-01

    This paper presents a comparison of volume extinction coefficients in tropical ice clouds retrieved from two instruments : the 532-nm Cloud Physics Lidar (CPL), and the in-situ probe Cloud Integrating Nephelometer (CIN). Both instruments were mounted on airborne platforms during the CRYSTAL-FACE campaign and took measurements in ice clouds up to 17km. Coincident observations from three cloud cases are compared : one synoptically-generated cirrus cloud of low optical depth, and two ice clouds located on top of convective systems. Emphasis is put on the vertical variability of the extinction coefficient. Results show small differences on small spatial scales (approx. 100m) in retrievals from both instruments. Lidar retrievals also show higher extinction coefficients in the synoptic cirrus case, while the opposite tendency is observed in convective cloud systems. These differences are generally variations around the average profile given by the CPL though, and general trends on larger spatial scales are usually well reproduced. A good agreement exists between the two instruments, with an average difference of less than 16% on optical depth retrievals.

  19. Remote and in situ observations of an unusual Earth-directed coronal mass ejection from multiple viewpoints

    NASA Astrophysics Data System (ADS)

    Nieves-Chinchilla, T.; Colaninno, R.; Vourlidas, A.; Szabo, A.; Lepping, R. P.; Boardsen, S. A.; Anderson, B. J.; Korth, H.

    2012-06-01

    During June 16-21, 2010, an Earth-directed coronal mass ejection (CME) event was observed by instruments onboard STEREO, SOHO, MESSENGER and Wind. This event was the first direct detection of a rotating CME in the middle and outer corona. Here, we carry out a comprehensive analysis of the evolution of the CME in the interplanetary medium comparing in situ and remote observations, with analytical models and three-dimensional reconstructions. In particular, we investigate the parallel and perpendicular cross section expansion of the CME from the corona through the heliosphere up to 1 AU. We use height-time measurements and the Gradual Cylindrical Shell (GCS) technique to model the imaging observations, remove the projection effects, and derive the 3-dimensional extent of the event. Then, we compare the results with in situ analytical Magnetic Cloud (MC) models, and with geometrical predictions from past works. We find that the parallel (along the propagation plane) cross section expansion agrees well with the in situ model and with the Bothmer and Schwenn (1998) empirical relationship based on in situ observations between 0.3 and 1 AU. Our results effectively extend this empirical relationship to about 5 solar radii. The expansion of the perpendicular diameter agrees very well with the in situ results at MESSENGER (˜0.5 AU) but not at 1 AU. We also find a slightly different, from Bothmer and Schwenn (1998), empirical relationship for the perpendicular expansion. More importantly, we find no evidence that the CME undergoes a significant latitudinal over-expansion as it is commonly assumed. Instead, we find evidence that effects due to CME rotation and expansion can be easily confused in the images leading to a severe overestimation of the proper 3D size of the event. Finally, we find that the reconstructions of the CME morphology from the in situ observations at 1 AU are in agreement with the remote sensing observations but they show a big discrepancy at MESSENGER

  20. Snow distribution on Antarctic sea ice: precipitation, accumulation, and connections to sea ice thickness from in situ and NASA IceBridge observations.

    NASA Astrophysics Data System (ADS)

    Maksym, T. L.; Kunz, C.; Kwok, R.; Leonard, K. C.; Singh, H.; Trujillo, E.; Williams, G. D.; White, S.; Wever, N.

    2014-12-01

    Snow plays a dominant role in Antarctic sea ice mass balance and its seasonal evolution. It is a primary control on sea ice thickness and the structure of sea ice ecosystems, it dominates the uncertainty in satellite estimates of ice thickness, and it may significantly modulate the response of sea ice to climate change and variability. Here, we provide an overview of recent surveys of snow distribution (both small and large scale), its temporal evolution, and its connection with the processes that drive it - precipitation, accumulation, blowing snow events, flooding, and the role of ice deformation. We present recent 3-D in situ floe-scale measurements of snow surface topography, snow depth, and ice thickness distribution that allow relationships between surface roughness features, snow accumulation, and ice thickness to be examined in unprecedented detail. These data are compared with estimates of snow depth from the NASA IceBridge radar from spring surveys in the Weddell and Amundsen/Bellingshausen Seas. Both airborne and in situ measurements suggest a significant extent of thick ice with a deep snow cover that is underrepresented in prior surveys. Finally, the seasonal evolution of precipitation, snow depth, and accumulation is examined with data from drifting buoy platforms deployed in several regions of the Antarctic. These observations show that precipitation is not necessarily a good estimator for snow accumulation and that treatment of blowing snow must be included for sea ice models to accurately simulate Antarctic snow and sea ice mass balance. The implications of these results for modeling and satellite measurement of the sea ice thickness distribution are discussed.

  1. In-situ observation of the transformation of amorphous calcium phosphate to crystalline hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Stammeier, Jessica; Hippler, Dorothee; Mavromatis, Vasileios; Sacher, Stephan; Dietzel, Martin

    2016-04-01

    Amorphous calcium phosphate (Ca3(PO4)2*nH2O; ACP) is often a precursor phase of the mineral (hydroxy-) apatite (Ca5(PO4)3(OH)) that can be formed in natural settings during both authigenic and biogenic mineral formation. Particularly, in the biomineralization process of fish tissue, ACP has shown to be an important transient phase. In solution ACP rapidly transforms into the crystalline phase. The transformation rate highly depends on the physico-chemical conditions of the solution: Ca & P availability, pH and temperature. In natural settings Ca can be provided by different sources: from (1) seawater, (2) porewater, or (3) diagenetically-altered carbonates, whereas local supersaturation of P can be induced by microbial activity. In this study, we performed phosphate precipitation experiments in order to monitor the transformation process of the ACP to crystalline hydroxyapatite (HAP) using in-situ Raman spectroscopy. During the experiments the temperature was kept constant at 20.0 ± 0.01 ° C and pH at 9 ± 0.1. 50 ml of 0.3 CaCl 2H2O was titrated at a rate of 5 ml/min to an equal volume of 0.2 M Na2HPO4. The pH was kept constant by titration of 1 M NaOH. During the experiment samples were taken from the solution and instantly filtered. The obtained solid samples were lyophilized and analyzed with XRD, ATR and SEM. The respective solution samples were analyzed using ion chromatography and ICP OES, coupling the spectroscopic data with detailed solution chemistry data. We observed transformation of ACP to HAP to occur within 14 hours, illustrated in a clear peak shift in Raman spectra from 950 cm-1 to 960 cm-1. The obtained results are discussed in the aspects of distribution of major elements during the formation of phosphates and/or the diagenetic alteration of carbonates to phosphates in geologic settings. Financial support by DFG-FG 736 and NAWI Graz is kindly acknowledged.

  2. Aerosol cloud interactions in southeast Pacific stratocumulus: satellite observations, in situ data and regional modeling

    NASA Astrophysics Data System (ADS)

    George, Rhea

    The influence of anthropogenic aerosols on cloud radiative properties in the persistent southeast Pacific stratocumulus deck is investigated using MODIS satellite observations, in situ data from the VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx), and WRF-Chem, a regional model with interactive chemistry and aerosols. An albedo proxy is derived based on the fractional coverage of low cloud (a macrophysical field) and the cloud albedo, with the latter broken down into contributions from microphysics (cloud droplet concentration, Nd and macrophysics (liquid water path). Albedo variability is dominated by low cloud fraction variability, except within 10-15° of the South American coast, where cloud albedo variability contributes significantly. Covariance between cloud fraction and cloud albedo also contributes significantly to the variance in albedo, which highlights how complex and inseparable the factors controlling albedo are. N d variability contributes only weakly, which emphasizes that attributing albedo variability to the indirect effects of aerosols against the backdrop of natural meteorological variability is extremely challenging. Specific cases of aerosol changes can have strong impacts on albedo. We identify a pathway for periodic anthropogenic aerosol transport to the unpolluted marine stratocumulus >1000 km offshore, which strongly enhances Nd and albedo in zonally-elongated 'hook'-shaped arc. Hook development occurs with Nd increasing to polluted levels over the remote ocean primarily due to entrainment of a large number of small aerosols from the free troposphere that contribute a relatively small amount of aerosol mass to the marine boundary layer. Strong, deep offshore flow needed to transport continental aerosols to the remote ocean is favored by a trough approaching the South American coast and a southeastward shift of the climatological subtropical high pressure system. DMS significantly influences the aerosol number and

  3. In-situ observation of the transformation of amorphous calcium phosphate to crystalline hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Stammeier, Jessica; Hippler, Dorothee; Mavromatis, Vasileios; Sacher, Stephan; Dietzel, Martin

    2016-04-01

    Amorphous calcium phosphate (Ca3(PO4)2*nH2O; ACP) is often a precursor phase of the mineral (hydroxy-) apatite (Ca5(PO4)3(OH)) that can be formed in natural settings during both authigenic and biogenic mineral formation. Particularly, in the biomineralization process of fish tissue, ACP has shown to be an important transient phase. In solution ACP rapidly transforms into the crystalline phase. The transformation rate highly depends on the physico-chemical conditions of the solution: Ca & P availability, pH and temperature. In natural settings Ca can be provided by different sources: from (1) seawater, (2) porewater, or (3) diagenetically-altered carbonates, whereas local supersaturation of P can be induced by microbial activity. In this study, we performed phosphate precipitation experiments in order to monitor the transformation process of the ACP to crystalline hydroxyapatite (HAP) using in-situ Raman spectroscopy. During the experiments the temperature was kept constant at 20.0 ± 0.01 ° C and pH at 9 ± 0.1. 50 ml of 0.3 CaCl 2H2O was titrated at a rate of 5 ml/min to an equal volume of 0.2 M Na2HPO4. The pH was kept constant by titration of 1 M NaOH. During the experiment samples were taken from the solution and instantly filtered. The obtained solid samples were lyophilized and analyzed with XRD, ATR and SEM. The respective solution samples were analyzed using ion chromatography and ICP OES, coupling the spectroscopic data with detailed solution chemistry data. We observed transformation of ACP to HAP to occur within 14 hours, illustrated in a clear peak shift in Raman spectra from 950 cm‑1 to 960 cm‑1. The obtained results are discussed in the aspects of distribution of major elements during the formation of phosphates and/or the diagenetic alteration of carbonates to phosphates in geologic settings. Financial support by DFG-FG 736 and NAWI Graz is kindly acknowledged.

  4. WaterML, an Information Standard for the Exchange of in-situ hydrological observations

    NASA Astrophysics Data System (ADS)

    Valentine, D.; Taylor, P.; Zaslavsky, I.

    2012-04-01

    The WaterML 2.0 Standards Working Group (SWG), working within the Open Geospatial Consortium (OGC) and in cooperation with the joint OGC-World Meteorological Organization (WMO) Hydrology Domain Working Group (HDWG), has developed an open standard for the exchange of water observation data; WaterML 2.0. The focus of the standard is time-series data, commonly generated from in-situ style monitoring. This is high value data for hydrological applications such as flood forecasting, environmental reporting and supporting hydrological infrastructure (e.g. dams, supply systems), which is commonly exchanged, but a lack of standards inhibits efficient reuse and automation. The process of developing WaterML required doing a harmonization analysis of existing standards to identify overlapping concepts and come to agreement on a harmonized definition. Generally the formats captured similar requirements, all with subtle differences, such as how time-series point metadata was handled. The in-progress standard WaterML 2.0 incorporates the semantics of the hydrologic information: location, procedure, and observations, and is implemented as an application schema of the Geography Markup Language version 3.2.1, making use of the OGC Observations & Measurements standards. WaterML2.0 is designed as an extensible schema to allow encoding of data to be used in a variety of exchange scenarios. Example areas of usage are: exchange of data for operational hydrological monitoring programs; supporting operation of infrastructure (e.g. dams, supply systems); cross-border exchange of observational data; release of data for public dissemination; enhancing disaster management through data exchange; and exchange in support of national reporting The first phase of WaterML2.0 focused on structural definitions allowing for the transfer of time-series, with less work on harmonization of vocabulary items such as quality codes. Vocabularies from various organizations tend to be specific and take time to

  5. High temperature in-situ observations of multi-segmented metal nanowires encapsulated within carbon nanotubes by in-situ filling technique

    PubMed Central

    2012-01-01

    Multi-segmented one-dimensional metal nanowires were encapsulated within carbon nanotubes (CNTs) through in-situ filling technique during plasma-enhanced chemical vapor deposition process. Transmission electron microscopy (TEM) and environmental TEM were employed to characterize the as-prepared sample at room temperature and high temperature. The selected area electron diffractions revealed that the Pd4Si nanowire and face-centered-cubic Co nanowire on top of the Pd nanowire were encapsulated within the bottom and tip parts of the multiwall CNT, respectively. Although the strain-induced deformation of graphite walls was observed, the solid-state phases of Pd4Si and Co-Pd remain even at above their expected melting temperatures and up to 1,550 ± 50°C. Finally, the encapsulated metals were melted and flowed out from the tip of the CNT after 2 h at the same temperature due to the increase of internal pressure of the CNT. PMID:22873841

  6. In situ stress observation in oxide films and how tensile stress influences oxygen ion conduction

    PubMed Central

    Fluri, Aline; Pergolesi, Daniele; Roddatis, Vladimir; Wokaun, Alexander; Lippert, Thomas

    2016-01-01

    Many properties of materials can be changed by varying the interatomic distances in the crystal lattice by applying stress. Ideal model systems for investigations are heteroepitaxial thin films where lattice distortions can be induced by the crystallographic mismatch with the substrate. Here we describe an in situ simultaneous diagnostic of growth mode and stress during pulsed laser deposition of oxide thin films. The stress state and evolution up to the relaxation onset are monitored during the growth of oxygen ion conducting Ce0.85Sm0.15O2-δ thin films via optical wafer curvature measurements. Increasing tensile stress lowers the activation energy for charge transport and a thorough characterization of stress and morphology allows quantifying this effect using samples with the conductive properties of single crystals. The combined in situ application of optical deflectometry and electron diffraction provides an invaluable tool for strain engineering in Materials Science to fabricate novel devices with intriguing functionalities. PMID:26912416

  7. In situ stress observation in oxide films and how tensile stress influences oxygen ion conduction

    NASA Astrophysics Data System (ADS)

    Fluri, Aline; Pergolesi, Daniele; Roddatis, Vladimir; Wokaun, Alexander; Lippert, Thomas

    2016-02-01

    Many properties of materials can be changed by varying the interatomic distances in the crystal lattice by applying stress. Ideal model systems for investigations are heteroepitaxial thin films where lattice distortions can be induced by the crystallographic mismatch with the substrate. Here we describe an in situ simultaneous diagnostic of growth mode and stress during pulsed laser deposition of oxide thin films. The stress state and evolution up to the relaxation onset are monitored during the growth of oxygen ion conducting Ce0.85Sm0.15O2-δ thin films via optical wafer curvature measurements. Increasing tensile stress lowers the activation energy for charge transport and a thorough characterization of stress and morphology allows quantifying this effect using samples with the conductive properties of single crystals. The combined in situ application of optical deflectometry and electron diffraction provides an invaluable tool for strain engineering in Materials Science to fabricate novel devices with intriguing functionalities.

  8. In-situ observation of dynamic recrystallization in the bulk of zirconium alloy.

    SciTech Connect

    Liss, K.-D.; Garbe, U.; Li, H. J.; Schambron, T.; Almer, J. D.; Yan, K.; Australian Nuclear Science and Tech. Organisation; Univ. of Wollongong

    2009-08-01

    Dynamic recrystallization and related effects have been followed in situ and in real time while a metal undergoes rapid thermo-mechanical processing. Statistics and orientation correlations of embedded/bulk material grains were deduced from two-dimensional X-ray diffraction patterns and give deep insight into the formation of the microstructure. Applications are relevant in materials design, simulation, and in geological systems.

  9. In Situ STEM-EELS observation of nanoscale interfacial phenomena in all-solid-state batteries

    DOE PAGES

    Wang, Ziying; Xin, Huolin L.; Santhanagopalan, Dhamodaran; Zhang, Wei; Wang, Feng; He, Kai; Li, Juchuan; Dudney, Nancy; Meng, Ying Shirley

    2016-05-03

    Behaviors of functional interfaces are crucial factors in the performance and safety of energy storage and conversion devices. Indeed, solid electrode–solid electrolyte interfacial impedance is now considered the main limiting factor in all-solid-state batteries rather than low ionic conductivity of the solid electrolyte. Here, we present a new approach to conducting in situ scanning transmission electron microscopy (STEM) coupled with electron energy loss spectroscopy (EELS) in order to uncover the unique interfacial phenomena related to lithium ion transport and its corresponding charge transfer. Our approach allowed quantitative spectroscopic characterization of a galvanostatically biased electrochemical system under in situ conditions. Usingmore » a LiCoO2/LiPON/Si thin film battery, an unexpected structurally disordered interfacial layer between LiCoO2 cathode and LiPON electrolyte was discovered to be inherent to this interface without cycling. During in situ charging, spectroscopic characterization revealed that this interfacial layer evolved to form highly oxidized Co ions species along with lithium oxide and lithium peroxide species. Here, these findings suggest that the mechanism of interfacial impedance at the LiCoO2/LiPON interface is caused by chemical changes rather than space charge effects. Insights gained from this technique will shed light on important challenges of interfaces in all-solid-state energy storage and conversion systems and facilitate improved engineering of devices operated far from equilibrium.« less

  10. In Situ STEM-EELS Observation of Nanoscale Interfacial Phenomena in All-Solid-State Batteries.

    PubMed

    Wang, Ziying; Santhanagopalan, Dhamodaran; Zhang, Wei; Wang, Feng; Xin, Huolin L; He, Kai; Li, Juchuan; Dudney, Nancy; Meng, Ying Shirley

    2016-06-01

    Behaviors of functional interfaces are crucial factors in the performance and safety of energy storage and conversion devices. Indeed, solid electrode-solid electrolyte interfacial impedance is now considered the main limiting factor in all-solid-state batteries rather than low ionic conductivity of the solid electrolyte. Here, we present a new approach to conducting in situ scanning transmission electron microscopy (STEM) coupled with electron energy loss spectroscopy (EELS) in order to uncover the unique interfacial phenomena related to lithium ion transport and its corresponding charge transfer. Our approach allowed quantitative spectroscopic characterization of a galvanostatically biased electrochemical system under in situ conditions. Using a LiCoO2/LiPON/Si thin film battery, an unexpected structurally disordered interfacial layer between LiCoO2 cathode and LiPON electrolyte was discovered to be inherent to this interface without cycling. During in situ charging, spectroscopic characterization revealed that this interfacial layer evolved to form highly oxidized Co ions species along with lithium oxide and lithium peroxide species. These findings suggest that the mechanism of interfacial impedance at the LiCoO2/LiPON interface is caused by chemical changes rather than space charge effects. Insights gained from this technique will shed light on important challenges of interfaces in all-solid-state energy storage and conversion systems and facilitate improved engineering of devices operated far from equilibrium.

  11. In-situ aircraft observations of ice supersaturation and cirrus clouds in global field studies

    NASA Astrophysics Data System (ADS)

    Diao, M.; Zondlo, M. A.

    2012-12-01

    Clouds play important roles in the Earth's climate and weather system, and the net forcing of all clouds results in a cooling effect on the Earth's surface. However, clouds remain one of the largest uncertainties in climate models. The IPCC AR4 report shows that both the magnitude and sign of the changes in cloud radiative forcing in response to anthropogenic aerosols are highly uncertain. Cirrus clouds are a type of ice clouds that occur at 235-185K with a net warming effect on the Earth surface. Cirrus cloud formation requires ice supersaturation (ISS), i.e., relative humidity with respect to ice (RHi) greater than 100%. Because ISS is critically related to the ice nucleation processes, it is also an indicator of any changes of ice nucleation and cirrus cloud formation. Here we use the in-situ 1 Hz aircraft observations by the Vertical Cavity Surface Emitting Laser (VCSEL) hygrometer on board the NSF Gulfstream-V research aircraft to analyze the differences of ISS distribution between the Northern and Southern Hemispheres (NH and SH). Our dataset is based on five deployments of the NSF Hiaper Pole-to-Pole Observations (HIPPO) Global field campaigns, including nine Pole-to-Pole transects from the year of 2009 to 2011, extending from 87°N to 67°S, covering four seasons, and the Stratosphere-Troposphere Analyses of Regional Transport (START08) campaign over North America region in April-June 2008. The flight track was mostly over the mid-Pacific Ocean, and also parts of the North America and Australia. We found that the frequency of ISS is much higher in NH than SH for the clear-sky conditions, while the in-cloud conditions show no significant difference between the two hemispheres. Our conclusion is in sharp contrast to the previous aircraft observations which concluded that the SH has higher frequency of ISS for clear-sky conditions based on two flight campaigns at Prestwick, Scotland (55°N) and Punta Arenas, Chile (55°S). We propose a method to separate

  12. In situ observation on hydrogenation of Mg-Ni films using environmental transmission electron microscope with aberration correction

    SciTech Connect

    Matsuda, Junko; Yoshida, Kenta; Sasaki, Yukichi; Uchiyama, Naoki; Akiba, Etsuo

    2014-08-25

    In situ transmission electron microscopy (TEM) was performed to observe the hydrogenation of Mg-Ni films in a hydrogen atmosphere of 80–100 Pa. An aberration-corrected environmental TEM with a differential pumping system allows us to reveal the Angstrom-scale structure of the films in the initial stage of hydrogenation: first, nucleation and growth of Mg{sub 2}NiH{sub 4} crystals with a lattice spacing of 0.22 nm in an Mg-rich amorphous matrix of the film occurs within 20 s after the start of the high-resolution observation, then crystallization of MgH{sub 2} with a smaller spacing of 0.15 nm happens after approximately 1 min. Our in situ TEM method is also applicable to the analysis of other hydrogen-related materials.

  13. Hydrometeor Profiles Derived from Airborne Radar and Wideband Radiometer Observations

    NASA Technical Reports Server (NTRS)

    Skofronick-Jackson, G. M.; Wang, J. R.; Heymsfield, G.; Hood, R.; Arnold, James E. (Technical Monitor)

    2000-01-01

    A rich dataset was obtained with observations from the MIR (Millimeter-wave Imaging Radiometer, 89, 150, 183.3$\\pm$1, 183.3$\\pm$3,183.3$\\pm$7, and 220 apprx.GHz), the AMPR (Advanced Microwave Precipitation Radiometer, 10.7, 19.35, 37, and 85 approx. GHz), and the EDOP (ER-2 Doppler Radar, 9.6 approx. GHz) on board the ER-2 aircraft during the CAMEX-3/TEFLUN-B (Convection and Moisture Experiment/Texas and Florida Underflights) TRMM (Tropical Rainfall Measuring Mission) field campaign. Measurements over the ocean from these three instruments on 26 August 1998 were used in our iterative retrieval algorithm to estimate hydrometeor drop size profiles, The algorithm attempts to minimize the difference between the observations and forward radiometer and radar calculations based on the estimated profile. The high frequency MIR observations provide detailed information about the high altitude ice microphysics, while the AMPR is mostly used to define liquid hydrometeor characteristics. The EDOP provides an initial estimate of the profile and as a consistency check throughout the iterative cycle. The retrieval algorithm, specific results for convective and anvil cases, and general implications of this work will be presented.

  14. Combination of satellite based thermal remote sensing and in situ radon measurements and field observations to detect (submarine) groundwater discharge

    NASA Astrophysics Data System (ADS)

    Mallast, U.; Schubert, M.; Schmidt, A.; Knoeller, K.; Stollberg, R.; Siebert, C.; Merz, R.

    2012-12-01

    air temperature course resulting in high temperature variability. The temperature variability analysis in combination with a pre-processing step in which images with surface-runoff influence are excluded outlines thermal anomalies that are directly attributable to SGD areas. We applied this method at three different locations along the Dead Sea (Israel/ Palestine), the Black Sea (Romania) and the Mediterranean Sea (France). The sites represent similar hydrogeological conditions (limestone) but different topographical (steep and flat) settings, groundwater temperatures and climatic conditions. We will show that despite these differences, which result in diverse SGD amounts and flux character, the method is capable of indicating areas where continuous SGD occurs over large spatial scales. Based on the thermal indications that were used as a prescreening tool in situ radon measurements and in case of the Dead Sea field observations were pursued to validate the thermal indications. We will show that both results match. Hence we state that our approach represents a promising tool (i) to detect SGD on large spatial scales particularly in areas where a priori no or limited information is available and (ii) to reduce time and financial efforts in pursuing subsequent SGD measurements as the outlined areas can be set as focus areas.

  15. LOCAL AIR: Local Aerosol monitoring combining in-situ and Remote Sensing observations

    NASA Astrophysics Data System (ADS)

    Mona, Lucia; Caggiano, Rosa; Donvito, Angelo; Giannini, Vincenzo; Papagiannopoulos, Nikolaos; Sarli, Valentina; Trippetta, Serena

    2015-04-01

    The atmospheric aerosols have effects on climate, environment and health. Although the importance of the study of aerosols is well recognized, the current knowledge of the characteristics and their distribution is still insufficient, and there are large uncertainties in the current understanding of the role of aerosols on climate and the environment, both on a regional and local level. Overcoming these uncertainties requires a search strategy that integrates data from multiple platforms (eg, terrestrial, satellite, ships and planes) and the different acquisition techniques (for example, in situ measurements, remote sensing, modeling numerical and data assimilation) (Yu et al., 2006). To this end, in recent years, there have been many efforts such as the creation of networks dedicated to systematic observation of aerosols (eg, European Monitoring and Evaluation Programme-EMEP, European Aerosol Research Lidar NETwork-EARLINET, MicroPulse Lidar Network- MPLNET, and Aerosol Robotic NETwork-AERONET), the development and implementation of new satellite sensors and improvement of numerical models. The recent availability of numerous data to the ground, columnar and profiles of aerosols allows to investigate these aspects. An integrated approach between these different techniques could be able to provide additional information, providing greater insight into the properties of aerosols and their distribution and overcoming the limits of each single technique. In fact, the ground measurements allow direct determination of the physico-chemical properties of aerosols, but cannot be considered representative for large spatial and temporal scales and do not provide any information about the vertical profile of aerosols. On the other hand, the remote sensing techniques from the ground and satellite provide information on the vertical distribution of atmospheric aerosols both in the Planetary Boundary Layer (PBL), mainly characterized by the presence of aerosols originating from

  16. Continental hydrology from satellite multi-sensor data and in situ observations

    NASA Astrophysics Data System (ADS)

    Kouraev, A. V.

    2009-04-01

    freshwater input into the Arabian Gulf, affecting fishery, marine biology and biogeochemistry. ET basin is shared by several countries and is extensively used for irrigation and other types for water consumption. Cascades of large reservoirs are constructed in each of the four countries. Information on hydrological regime of the ET basin (water level in the reservoirs, amount of diverted water, river level and discharge) has paramount importance for studies of natural and anthropogenic influence on ET river system, and freshwater input into the Arabian Gulf. We present the results of studies for these two regions basing on our existing experience of using in situ data together with remote sensing techniques such as radar altimetry (TOPEX/Poseidon, Jason-1, GFO, ENVISAT), radiometry (SMMR, SSM/I), optical data (MODIS, Landsat) and space gravimetry data (GRACE). We analyse several parameters: a) water level in reservoirs and wetlands, b) river level and river discharge, c) water abundance and flooded area extent, and d) snow and ice cover (for Western Siberia). Research has been done in the framework of the Russian-French cooperation GDRI CAR-WET-SIB, French ANR IMPACT-Boreal project, and SMOS AO No. 4648.

  17. Combined Multipoint Remote and In Situ Observations of the Asymmetric Evolution of a Fast Coronal Mass Ejection

    NASA Astrophysics Data System (ADS)

    Rollett, Tanja; Möstl, Christian; Temmer, Manuela; Frahm, Rudy A.; Davies, Jackie A.; Veronig, Astrid M.; Vrsnak, Bojan; Amerstorfer, Ute V.; Farrugia, Charles J.; Zic, Tomislav; Zhang, Tielong

    2015-04-01

    A significant number of in situ detections and remote observations have allowed us to strongly constrain the shape of the fast coronal mass ejection (CME) of 7 March 2012 during its evolution through interplanetary space. The CME was imaged by both STEREO spacecraft and detected in situ by MESSENGER, Venus Express, Wind and Mars Express. Applying the novel constrained self-similar expansion method, which combines observations from STEREO's heliospheric imaging facilities with the four in situ detections, we derived different kinematical profiles for two different segments of the same CME. For the Venus- (and Mercury-) directed segment we found a gradual deceleration while the Earth- (and Mars-) directed part was decelerated abruptly close to the Sun. In order to study the background solar wind conditions we used a drag-based model, which revealed a comparatively small drag-force acting on the Venus-directed CME segment possibly caused by a preceding CME that cleared the way for the CME under study. The Earth-directed segment may have also been affected by a preceding CME. Here, we found different solar wind conditions along the CME path. A high drag-parameter below 35 solar radii suggests a high drag-force acting against the CME propagation, causing a strong deceleration. Subsequently, this part of the CME propagated with an almost constant speed. The resulting deformation of the overall CME shape underlines the importance of using stereoscopic observations for being able to reduce the arrival time error in space weather forecasting.

  18. Airborne Millimeter-Wave Radiometric Observations of Cirrus Clouds

    NASA Technical Reports Server (NTRS)

    Wang, J. R.; Racette, P.

    1997-01-01

    This paper reports the first radiometric measurements of cirrus clouds in the frequency range of 89-325 GHz from a high-altitude aircraft flight. The measurements are conducted with a Millimeter-wave Imaging Radiometer (MIR) on board the NASA ER-2 aircraft over a region in northern Oklahoma. Aboard the same aircraft are a cloud lidar system and a multichannel radiometer operating at the visible and infrared wavelengths. The instrument ensemble is well suited for identifying cirrus clouds. It is shown that the depressions in brightness temperatures associated with a few intense cirrus clouds occur at all frequency channels of the MIR. Estimates of total ice water path of the cirrus clouds are derived from comparisons of radiative transfer calculations and observed brightness depressions.

  19. Evaluation of the NASA Langley Research Center airborne High Spectral Resolution Lidar extinction measurements during the Megacity Initiative: Local and Global Research Observations (MILAGRO) Campaign

    NASA Astrophysics Data System (ADS)

    Rogers, R. R.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Cook, A. L.; Harper, D. B.; Obland, M. D.; Burton, S. P.; Clarke, A. D.; Russell, P. B.; Redemann, J.; Livingston, J. M.

    2007-12-01

    The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) was deployed on the NASA LaRC B-200 King Air aircraft and measured profiles of aerosol extinction, backscatter, and depolarization during the Megacity Initiative: Local and Global Research Observations (MILAGRO) Campaign in March 2006. The HSRL collected approximately 55 hours of data over 15 science flights, which were coordinated with the Sky Research J-31 aircraft (5 flights), the DOE G-1 aircraft (6 flights), and the NCAR C-130 aircraft (4 flights). This coordinated effort in MILAGRO provides the first opportunity to evaluate the HSRL aerosol extinction and optical thickness profiles with corresponding profiles derived from the other airborne measurements: 1) the 14 channel NASA Ames Airborne Tracking Sunphotometer (AATS-14) on the J-31 and the in situ nephelometer measurements of aerosol scattering and Particle Soot Absorption Photometer (PSAP) measurements of aerosol absorption from the Hawaii Group for Environment and Atmospheric Research (HiGEAR) on the C-130. This study will include comparisons of aerosol extinction from these three techniques in cases where the HSRL flew directly over the AATS-14 and HiGEAR instruments while they measured aerosol extinction profiles. The results are used in assessing the uncertainty of the HSRL extinction profiles. Column aerosol optical depth (AOD) derived from the HSRL measurements is also compared with AOD derived from Moderate Resolution Imaging Spectroradiometer (MODIS) measurements acquired on the Terra and Aqua spacecraft and from Aerosol Robotic Network (AERONET) ground-based Sun photometer measurements.

  20. Top-view approach for in-situ observation of growth morphology in bulk transparent organic alloys

    NASA Astrophysics Data System (ADS)

    Witusiewicz, V. T.; Hecht, U.; Rex, S.

    2012-08-01

    A new experimental method for in-situ observation of microstructure formation in top view during unidirectional solidification of bulk, transparent, organic alloys is presented. This method allows observing growth patterns over an extended interface area with high resolution and minimal optical aberrations. With (D)camphor-neopentylglycol-succinonitrile (DC-NPG-SCN) alloys a series of unidirectional solidification experiments were performed in order to validate the set-up. By means of multi-focus exposition eutectic cells were observed over a depth of several millimeters, followed by 3D reconstruction of their shape. The method also allows capturing the integral interface dynamics and measuring its relative undercooling.

  1. Airborne Observations of Aerosol Emissions from F-16 Aircraft

    NASA Technical Reports Server (NTRS)

    Anderson, B. E.; Cofer, W. R.; McDougal, D. S.

    1999-01-01

    We presented results from the SASS Near-Field Interactions Flight (SNIF-III) Experiment which was conducted during May and June 1997 in collaboration with the Vermont and New Jersey Air National Guard Units. The project objectives were to quantify the fraction of fuel sulfur converted to S(VI) species by jet engines and to gain a better understanding of particle formation and growth processes within aircraft wakes. Size and volatility segregated aerosol measurements along with sulfur species measurements were recorded in the exhaust of F-16 aircraft equipped with F-100 engines burning fuels with a range of fuel S concentrations at different altitudes and engine power settings. A total of 10 missions were flown in which F-16 exhaust plumes were sampled by an instrumented T-39 Sabreliner aircraft. On six of the flights, measurements were obtained behind the same two aircraft, one burning standard JP-8 fuel and the other either approximately 28 ppm or 1100 ppm S fuel or an equal mixture of the two (approximately 560 ppm S). A pair of flights was conducted for each fuel mixture, one at 30,000 ft altitude and the other starting at 35,000 ft and climbing to higher altitudes if contrail conditions were not encountered at the initial flight level. In each flight, the F-16s were operated at two power settings, approx. 80% and full military power. Exhaust emissions were sampled behind both aircraft at each flight level, power setting, and fuel S concentration at an initial aircraft separation of 30 m, gradually widening to about 3 km. Analyses of the aerosol data in the cases where fuel S was varied suggest results were consistent with observations from project SUCCESS, i.e., a significant fraction of the fuel S was oxidized to form S(VI) species and volatile particle emission indices (EIs) in comparably aged plumes exhibited a nonlinear dependence upon the fuel S concentration. For the high sulfur fuel, volatile particle EIs in 10-second-old-plumes were 2 to 3 x 10 (exp 17

  2. Maintaining Situation Awareness with Autonomous Airborne Observation Platforms

    NASA Technical Reports Server (NTRS)

    Freed, Michael; Fitzgerald, Will

    2005-01-01

    Unmanned Aerial Vehicles (UAVs) offer tremendous potential as intelligence, surveillance and reconnaissance (ISR) platforms for early detection of security threats and for acquisition and maintenance of situation awareness in crisis conditions. However, using their capabilities effectively requires addressing a range of practical and theoretical problems. The paper will describe progress by the "Autonomous Rotorcraft Project," a collaborative effort between NASA and the U.S. Army to develop a practical, flexible capability for UAV-based ISR. Important facets of the project include optimization methods for allocating scarce aircraft resources to observe numerous, distinct sites of interest; intelligent flight automation software than integrates high-level plan generation capabilities with executive control, failure response and flight control functions; a system architecture supporting reconfiguration of onboard sensors to address different kinds of threats; and an advanced prototype vehicle designed to allow large-scale production at low cost. The paper will also address human interaction issues including an empirical method for determining how to allocate roles and responsibilities between flight automation and human operations.

  3. Prediction of Geomagnetic Storm Strength from Inner Heliospheric In Situ Observations

    NASA Astrophysics Data System (ADS)

    Kubicka, M.; Moestl, C.; Rollett, T.; Feng, L.; Eastwood, J. P.; Boakes, P. D.

    2015-12-01

    In order to predict the effects of interplanetary coronal mass ejections (ICMEs) on Earth, it is important to know the properties of the interplanetary magnetic field (IMF). Of special interest is the southward component (Bz) of the IMF, acting as a main driver for geomagnetic storms. We are working on a proof-of-concept for predicting the strength of geomagnetic storms caused by ICMEs by using in situ data from spacecraft in the inner heliosphere. Our prediction includes the arrival time and speed of the ICME at Earth, the IMF's Bz component and the resulting disturbance storm time index (Dst), which is a prime indicator of geomagnetic activity. For Dst forecasting, the two well established models Burton et al. (1975) and O'Brien & McPherron (2000) are used. Necessary parameters for those models are the ICME speed and the Bz component of the IMF at 1 AU. We obtain the ICME speed using a drag-based model, and the IMF's Bz component is predicted based on a power law from the in situ data. Additionally, the ENLIL/WSA model provides the solar wind background speed for the drag-based model.An advantage of our method is the use of the in situ spacecraft as a reference point for the drag based-model, leading to a more precise arrival speed of the ICME at Earth, and an improved arrival time. Investigation of an ICME in June 2012 shows already very promising results for the Dst index, as well as for the ICME arrival speed. The main advantage of this method is the prediction lead time of ~21 hours compared to only ~40-60 minutes, using an L1 located spacecraft. Furthermore, the feasibility of this method can be studied with any in situ spacecraft temporarily located between the Sun and Earth, like Helios, Solar Orbiter or Solar Probe Plus, and also works for radial spacecraft alignments. The techniques we develop could be routinely applied to a mission that forms an artificial Lagrange point along the Sun-Earth line, e.g. for a Sunjammer or Heliostorm mission.

  4. In situ microscopic observation of chitin and fungal cells with chitinous cell walls in hydrothermal conditions.

    PubMed

    Deguchi, Shigeru; Tsujii, Kaoru; Horikoshi, Koki

    2015-07-07

    Recent findings of intact chitin in fossil records suggest surprisingly high recalcitrance of this biopolymer during hydrothermal treatments. We also know in the experience of everyday life that mushroom, cells of which have chitinous cell walls, do not fall apart however long they are simmered. We used in situ optical microscopy to examine chitin and fungal cells with chitinous cell walls during hydrothermal treatments, and obtained direct evidence that they remained undegraded at temperatures well over 200 °C. The results show very hot and compressed water is needed to make mushrooms mushy.

  5. In situ observation of ErD2 formation during D-2 loading via neutron diffraction

    SciTech Connect

    Browning, Jim; Snow, Clark; Wixom, Ryan R; Llobet, Anna; Rodriguez, Mark

    2011-01-01

    In an effort to better understand the structural changes occurring during hydrogen loading of erbium target materials, we have performed in situ D{sub 2} loading of erbium metal (powder) at temperature (450 C) with simultaneous neutron diffraction analysis. This experiment tracked the conversion of Er metal to the {alpha} erbium deuteride (solid-solution) phase and then into the {beta} (fluorite) phase. Complete conversion to ErD{sub 2.0} was accomplished at 10 Torr D{sub 2} pressure with deuterium fully occupying the tetrahedral sites in the fluorite lattice.

  6. In situ microscopic observation of chitin and fungal cells with chitinous cell walls in hydrothermal conditions

    PubMed Central

    Deguchi, Shigeru; Tsujii, Kaoru; Horikoshi, Koki

    2015-01-01

    Recent findings of intact chitin in fossil records suggest surprisingly high recalcitrance of this biopolymer during hydrothermal treatments. We also know in the experience of everyday life that mushroom, cells of which have chitinous cell walls, do not fall apart however long they are simmered. We used in situ optical microscopy to examine chitin and fungal cells with chitinous cell walls during hydrothermal treatments, and obtained direct evidence that they remained undegraded at temperatures well over 200 °C. The results show very hot and compressed water is needed to make mushrooms mushy. PMID:26148792

  7. An Airborne Infrared Telescope and Spectrograph for Solar Eclipse Observations

    NASA Astrophysics Data System (ADS)

    DeLuca, Edward E.; Cheimets, Peter; Golub, Leon

    2014-06-01

    The solar infrared spectrum offers great possibilities for direct spatially resolved measurements of the solar coronal magnetic fields, via imaging of the plasma that is constrained to follow the magnetic field direction and via spectro-polarimetry that permits measurement of the field strength in the corona. Energy stored in coronal magnetic fields is released in flares and coronal mass ejections (CME) and provides the ultimate source of energy for space weather. The large scale structure of the coronal field, and the opening up of the field in a transition zone between the closed and open corona determines the speed and structure of the solar wind, providing the background environment through which CMEs propagate. At present our only direct measurements of the solar magnetic fields are in the photosphere and chromosphere. The ability to determine where and why the corona transitions from closed to open, combined with measurements of the field strength via infrared coronal spectro-polarimetry will give us a powerful new tool in our quest to develop the next generation of forecasting models.We describe a first step in achieving this goal: a proposal for a new IR telescope, image stabilization system, and spectrometer, for the NCAR HIPER GV aircraft. The telescope/spectrograph will operate in the 2-6micron wavelength region, during solar eclipses, starting with the trans-north American eclipse in August 2017. The HIAPER aircraft flying at ~35,000 ft will provide an excellent platform for IR observations. Our imaging and spectroscopy experiment will show the distribution and intensity of IR forbidden lines in the solar corona.

  8. Direct observation of Lomer-Cottrell locks during strain hardening in nanocrystalline nickel by in situ TEM.

    PubMed

    Lee, Joon Hwan; Holland, Troy B; Mukherjee, Amiya K; Zhang, Xinghang; Wang, Haiyan

    2013-01-01

    Strain hardening capability is critical for metallic materials to achieve high ductility during plastic deformation. A majority of nanocrystalline metals, however, have inherently low work hardening capability with few exceptions. Interpretations on work hardening mechanisms in nanocrystalline metals are still controversial due to the lack of in situ experimental evidence. Here we report, by using an in situ transmission electron microscope nanoindentation tool, the direct observation of dynamic work hardening event in nanocrystalline nickel. During strain hardening stage, abundant Lomer-Cottrell (L-C) locks formed both within nanograins and against twin boundaries. Two major mechanisms were identified during interactions between L-C locks and twin boundaries. Quantitative nanoindentation experiments recorded show an increase of yield strength from 1.64 to 2.29 GPa during multiple loading-unloading cycles. This study provides both the evidence to explain the roots of work hardening at small length scales and the insight for future design of ductile nanocrystalline metals.

  9. In Situ TEM Observations on the Sulfur-Assisted Catalytic Growth of Single-Wall Carbon Nanotubes.

    PubMed

    Zhang, Lili; Hou, Peng-Xiang; Li, Shisheng; Shi, Chao; Cong, Hong-Tao; Liu, Chang; Cheng, Hui-Ming

    2014-04-17

    The effect of sulfur on the catalytic nucleation and growth of single-wall carbon nanotubes (SWCNTs) from an iron catalyst was investigated in situ by transmission electron microscopy (TEM). The catalyst precursor of ferrocene and growth promoter of sulfur were selectively loaded inside of the hollow core of multiwall CNTs with open ends, which served as a nanoreactor powered by applying a voltage inside of the chamber of a TEM. It was found that a SWCNT nucleated and grew perpendicularly from a region of the catalyst nanoparticle surface, instead of the normal tangential growth that occurs with no sulfur addition. Our in situ TEM observation combined with CVD growth studies suggests that sulfur functions to promote the nucleation and growth of SWCNTs by forming inhomogeneous local active sites and modifying the interface bonding between catalysts and precipitated graphitic layers, so that carbon caps can be lifted off from the catalyst particle. PMID:26269989

  10. High-latitude E Region Ionosphere-thermosphere Coupling: A Comparative Study Using in Situ and Incoherent Scatter Radar Observations

    NASA Technical Reports Server (NTRS)

    Burchill, J. K.; Clemmons, J. H.; Knudsen, D. J.; Larsen, M.; Nicolls, M. J.; Pfaff, R. F.; Rowland, D.; Sangalli, L.

    2012-01-01

    We present in situ and ground-based measurements of the ratio k of ion cyclotronangular frequency to ion-neutral momentum transfer collision frequency to investigateionosphere-thermosphere (IT) coupling in the auroral E region. In situ observations were obtained by NASA sounding rocket 36.234, which was launched into the nightsideE region ionosphere at 1229 UT on 19 January 2007 from Poker Flat, AK. The payload carried instrumentation to determine ion drift angle and electric field vectors. Neutral winds were measured by triangulating a chemical tracer released from rocket 41.064 launched two minutes later. k is calculated from the rotation of the ion drift angle relative to the E-cross-B drift direction in a frame co-rotating with the payload. Between the altitudes of 118 km and 130 km k increases exponentially with a scale height of 9.3 +/- 0.7 km, deviating from an exponential above 130 km. k = 1 at an altitude z(sub0) of 119.9 +/- 0.5 km. The ratio was also estimated from Poker Flat Incoherent Scatter Radar (PFISR) measurements using the rotation of ion velocity with altitude. Exponential fits to the PFISR measurements made during the flight of 41.064 yield z(sub0) 115.9 +/- 1.2 km and a scale height of 9.1 +/- 1.0 km. Differences between in situ and ground-based measurements show that the E region atmospheric densities were structured vertically and/or horizontally on scales of 1 km to 10 km. There were no signs of ionospheric structure in ion density or ion temperature below scales of 1 km. The observations demonstrate the accuracy with which the in situ and PFISR data may be used as probes of IT coupling.

  11. Assessment of a multi-species in-situ FTIR for precise atmospheric greenhouse gas observations

    NASA Astrophysics Data System (ADS)

    Hammer, S.; Griffith, D. W. T.; Konrad, G.; Vardag, S.; Caldow, C.; Levin, I.

    2012-05-01

    We thoroughly evaluate the performance of a multi-species, in-situ FTIR analyser with respect to high accuracy needs for greenhouse gas monitoring networks. The in-situ FTIR analyser measures CO2, CO, CH4 and N2O mole fractions continuously, all with better reproducibility than requested by the WMO-GAW inter-laboratory compatibility (ILC) goal. Simultaneously determined δ13CO2 reaches reproducibility as good as 0.03‰. This paper focuses on the quantification of residual dependencies between the measured components and the thermodynamic properties of the sample as well as the cross-sensitivities among the sample constituents. The instrument has proven to be linear for all components in the ambient range. The temporal stability of the instrument was investigated by 10 months of continuously collected quality control measures. Based on these measures we conclude that for moderately stable laboratory conditions weekly calibrations of the instrument are sufficient to reach WMO-GAW ILC goals.

  12. In Situ EBSD Observations of the Evolution in Crystallographic Orientation with Deformation

    NASA Astrophysics Data System (ADS)

    Wright, Stuart I.; Suzuki, Seiichi; Nowell, Matthew M.

    2016-09-01

    Automated electron backscatter diffraction (EBSD) analysis is frequently used to investigate the change in crystallographic orientation that occurs when polycrystalline materials deform. Through crystallographic slip, the crystal lattice within a grain rotates. However, the crystal lattice rotation in each grain is constrained by the lattices of the neighboring grains while rotating. These competing factors lead to the development of orientation gradients and substructure in deformed polycrystals. In situ uniaxial tensile deformation was carried out in the scanning electron microscope while employing simultaneous automated EBSD analysis to characterize grain rotation, both in terms of the overall rotation of the lattice and the development of orientation gradients within the grain. The impact of these factors can be seen at the grain boundaries in the deformed structure where the local orientations diverge from the orientation at the grain interior. Automated in situ EBSD analysis allows the quantitative nature of specific metrics based on local variations in orientation to illuminate the physical mechanisms underlying the stress strain response during a mechanical test.

  13. Wave-induced boundary-layer separation: A case study comparing airborne observations and results from a mesoscale model

    NASA Astrophysics Data System (ADS)

    Strauss, L.; Serafin, S.; Grubišić, V.

    2012-04-01

    light onto the limits of validity of airborne observations and mesoscale modelling. For example, the exact timing, magnitude, and evolution of the internal gravity waves present in the mesoscale model are carefully analysed. As for the observations, measures of turbulence gained from in situ and radar data, collected over complex topography within a limited period of time, must be interpreted with caution. Approaches to tackling these challenges are a matter of ongoing research and will be discussed in concluding.

  14. New species, corallivory, in situ video observations and overview of the Goniasteridae (Valvatida, Asteroidea) in the Hawaiian Region.

    PubMed

    Mah, Christopher L

    2015-01-01

    Two new species of Goniasteridae, Astroceramus eldredgei n. sp. and Apollonaster kelleyi n. sp. are described from the Hawaiian Islands region. Prior to this occurrence, Apollonaster was known only from the North Atlantic. The Goniasteridae is the most diverse family of asteroids in the Hawaiian region. Additional in situ observations of several goniasterid species, including A. eldredgei n. sp. are reported. These observations extend documentation of deep-sea corallivory among goniasterid asteroids. New species occurrences presented herein suggested further biogeographic affinities between tropical Pacific and Atlantic goniasterid faunas. PMID:25781779

  15. In situ TEM observation of electrochemical lithiation of sulfur confined within inner cylindrical pores of carbon nanotubes

    DOE PAGES

    Kim, Hyea; Lee, Jung Tae; Magasinski, Alexandre; Zhao, Kejie; Liu, Yang; Yushin, Gleb

    2015-10-26

    Lithium insertion into sulfur confined within 200 nm cylindrical inner pores of individual carbon nanotubes (CNTs) was monitored in-situ in a transmission electron microscope (TEM). This electrochemical reaction was initiated at one end of the S-filled CNTs. The material expansion during lithiation was accommodated by the expansion into the remaining empty pore volume and no fracture of the CNT walls was detected. A sharp interface between the initial and lithiated S was observed. The reaction front was flat, oriented perpendicular to the confined S cylinder and propagated along the cylinder length. Lithiation of S in the proximity of conductive carbonmore » proceeded at the same rate as the one in the center of the pore, suggesting the presence of electron pathways at the Li2S/S interface. Density of states (DOS) calculations further confirmed this hypothesis. In-situ electron diffraction showed a direct phase transformation of S into nanocrystalline Li2S without detectable formation of any intermediates, such as polysulfides and LiS. These important insights may elucidate some of the reaction mechanisms and guide the improvements in the design of C-S nanocomposites for high specific energy Li-S batteries. As a result, the proposed use of conductive CNTs with tunable pore diameter as cylindrical reaction vessels for in-situ TEM studies of electrochemical reactions proved to be highly advantageous and may help to resolve the on-going problems in battery technology.« less

  16. Height-resolved Scaling Properties of Tropospheric Water Vapour based on Airborne Lidar Observations

    NASA Astrophysics Data System (ADS)

    Kiemle, Christoph; Fischer, Lucas; Craig, George C.

    2013-04-01

    Two-dimensional vertical water vapour cross sections of the free troposphere between altitudes of 2 and 10 km, measured by nadir-viewing airborne differential-absorption lidar with high spatial resolution, were analyzed using structure functions up to the fifth order. We found scale invariance, i.e. a power-law dependency of structure function on length scale, for scales between 5 and 100 km, for the horizontal time series of water vapour mixing ratio. In contrast to one-dimensional in situ measurements, the two-dimensional water vapor lidar observations allow height-resolved analyses of power-law scaling exponents at a vertical resolution of 200 m. The data reveal significantly different scaling properties above and below an air-mass boundary. They stem from three very dissimilar aircraft campaigns: COPS/ETReC over middle and southern Europe in summer 2007, T-PARC around Japan mostly over sea in late summer 2008, and T-IPY around Spitsbergen over sea in winter 2008. After discarding flight segments with low lidar signals or large data gaps, and after averaging horizontally to a resolution of between 1 and 5 km to obtain a high signal to noise ratio, structure functions were computed for 20 flights at various heights, adding up to a length of more than 300,000 km. The power-law scaling exponents of the structure functions do not show significant latitudinal, seasonal or land/sea dependency, but they do differ between air masses influenced by moist convection and air masses aloft, not influenced. A classification of the horizontal water vapour time series into two groups according to whether the series occurred above or below the level of nearby convective cloud tops could be performed by detecting the cloud top height from the lidar backscatter signal in the corresponding flight segment. We found that the scaling exponents can be divided into two groups depending on the respective air mass: The smoothness of the time series, expressed by the first-order scaling

  17. Height-resolved Scaling Properties of Water Vapor in the Mesoscale using Airborne Lidar Observations

    NASA Astrophysics Data System (ADS)

    Fischer, L.; Craig, G. C.; Kiemle, C.

    2012-12-01

    Free tropospheric water vapor variability, measured by long-range airborne differential-absorption lidar, has been analyzed by using structure functions of different orders at altitudes from 2 to 10 km. It is shown that the water vapor field exhibits scale invariance at spatial scales ranging from 5km to 100km, where scaling behavior is defined as a power law dependence of structure functions on length scale. In contrast to one-dimensional in situ measurements, two-dimensional water vapor lidar observations allow height-resolved analysis of scaling exponents with a vertical resolution of 200m. Using this data a clear distinction was found between scaling properties above and below an air-mass boundary. Data has been analysed from three campaigns, COPS/ETReC (2007) collected during summertime in middle and south Europe, T-PARC (2008) collected during late summer around Japan mostly over sea and T-IPY (2008) collected during winter around Spitsbergen mostly over sea. After discarding flights with low lidar signals or large data gaps, and after horizontal averaging to a resolution of 1-5km to obtain a high signal to noise ratio, structure functions were computed for 20 flights at various heights with a total length of more than 300,000 km. Scaling exponents were obtained for structure functions up to fifth order, and results will be presented for first and second order structure functions and for intermittency (variation of the scaling exponent with increasing order). The scaling exponents show no significant latitudinal, seasonal and land/sea dependence, but show significantly different behavior depending on whether the time series occured in an air mass influenced by cumulus convection or not. A classification of the time series into two groups according to whether the series occurred above or below the level of nearby convective cloud tops was performed by detecting the cloud height from the lidar backscatter signal of the corresponding flight. It was found that

  18. Simultaneous, dual-point, in situ measurements of ionospheric structures using space tethers: TSS-1R observations

    NASA Astrophysics Data System (ADS)

    Indiresan, R. S.; Gilchrist, B. E.; Basu, S.; Lebreton, J.-P.; Szuszczewicz, E. P.

    First ever simultaneous, dual-point, in situ measurements of natural ionospheric structures using widely spaced tethered sensors, flying in formation, were made during the reflight of the Tethered Satellite System (TSS-1R) mission. A “target-of-opportunity” observation provided a direct comparison of structured ionospheric irregularity features at two altitudes near the South American geomagnetic equator at approximately 2000 hours local time and at an altitude of ≈300 km. With the TSS-1R satellite and space shuttle separated by a vertical distance of 10 km, correlated plasma signatures detected by plasma instruments at each end indicated a strong eastward displacement in the irregularity features and possible growth of steepened features at the higher altitude. Observations made by a SUNDIAL ground station ionosonde located north of the flight path also indicated considerable spread-F activity at the time. A SUNDIAL corrected ionospheric model indicated that the shuttle was flying near the F-peak. Therefore, the strongly correlated in situ observations were most likely associated with irregularities in their early development or modulations near the F-peak due to equatorial spread-F (ESF). While the TSS-1R system was not optimized for dual-point in situ ionospheric measurements, and the tether break eliminated additional equatorial zone observations planned for later in the mission, the results reported here nevertheless indicate that vertically correlated plasma features can exist and can also have strong structural variations as a function of altitude. Such variations need closer examination in order to understand their effects on radiowave scintillation. These observations also demonstrated the feasibility of tethered sensors in the study of ionospheric irregularities using controlled vertical sampling.

  19. Analysis of motor vehicle emissions over eastern Los Angeles, California from in-situ airborne measurements of trace gases and particulates during CalNex

    NASA Astrophysics Data System (ADS)

    Pollack, I. B.; Ryerson, T. B.; Trainer, M.; Frost, G. J.; Holloway, J. S.; McKeen, S. A.; Peischl, J.; Fahey, D. W.; Perring, A.; Schwarz, J. P.; Spackman, J. R.

    2010-12-01

    In-situ measurements of trace gases and particulates were acquired on the instrumented NOAA WP-3D aircraft during the CalNex (California Research at the Nexus of Air Quality and Climate Change) field study in May and June 2010. Multiple daytime research flights under similar meteorological conditions provide a sufficient data set for characterizing automobile emissions over the eastern Los Angeles (eLA) area of the South Coast air basin. Ratios of nitrogen oxides (NOx) and black carbon (BC) to carbon monoxide (CO) are used to isolate emissions of light duty vehicles from those of medium/heavy duty diesel trucks. Observations in the mixed boundary layer for the eLA area are separated according to latitude, longitude, and altitude. Industrial influences are eliminated by filtering the data according to SO2 mixing ratio and wind direction. The resulting correlations show weekday-to-weekend differences in enhancement ratios of NOx to CO and BC to CO, indicating a general tendency for higher emissions from heavy duty vehicles during the week. The CalNex data over eLA in 2010 will be compared to eLA data from a research flight in May 2002 by the WP-3D aircraft during the Intercontinental Transport and Chemical Transformation (ITCT) field study.

  20. In situ observation of deformation processes in nanocrystalline face-centered cubic metals

    PubMed Central

    Kobler, Aaron; Brandl, Christian; Hahn, Horst

    2016-01-01

    Summary The atomistic mechanisms active during plastic deformation of nanocrystalline metals are still a subject of controversy. The recently developed approach of combining automated crystal orientation mapping (ACOM) and in situ straining inside a transmission electron microscope was applied to study the deformation of nanocrystalline PdxAu1− x thin films. This combination enables direct imaging of simultaneously occurring plastic deformation processes in one experiment, such as grain boundary motion, twin activity and grain rotation. Large-angle grain rotations with ≈39° and ≈60° occur and can be related to twin formation, twin migration and twin–twin interaction as a result of partial dislocation activity. Furthermore, plastic deformation in nanocrystalline thin films was found to be partially reversible upon rupture of the film. In conclusion, conventional deformation mechanisms are still active in nanocrystalline metals but with different weighting as compared with conventional materials with coarser grains. PMID:27335747

  1. Strength, Hardening, and Failure Observed by In Situ TEM Tensile Testing.

    PubMed

    Kiener, Daniel; Kaufmann, Petra; Minor, Andrew M

    2012-11-01

    We present in situ transmission electron microscope tensile tests on focused ion beam fabricated single and multiple slip oriented Cu tensile samples with thicknesses in the range of 100-200 nm. Both crystal orientations fail by localized shear. While failure occurs after a few percent plastic strain and limited hardening in the single slip case, the multiple slip samples exhibit extended homogenous deformation and necking due to the activation of multiple dislocation sources in conjunction with significant hardening. The hardening behavior at 1% plastic strain is even more pronounced compared to compression samples of the same orientation due to the absence of sample taper and the interface to the compression platen. Moreover, we show for the first time that the strain rate sensitivity of such FIB prepared samples is an order of magnitude higher than that of bulk Cu.

  2. In situ observation of deformation processes in nanocrystalline face-centered cubic metals.

    PubMed

    Kobler, Aaron; Brandl, Christian; Hahn, Horst; Kübel, Christian

    2016-01-01

    The atomistic mechanisms active during plastic deformation of nanocrystalline metals are still a subject of controversy. The recently developed approach of combining automated crystal orientation mapping (ACOM) and in situ straining inside a transmission electron microscope was applied to study the deformation of nanocrystalline Pd x Au1- x thin films. This combination enables direct imaging of simultaneously occurring plastic deformation processes in one experiment, such as grain boundary motion, twin activity and grain rotation. Large-angle grain rotations with ≈39° and ≈60° occur and can be related to twin formation, twin migration and twin-twin interaction as a result of partial dislocation activity. Furthermore, plastic deformation in nanocrystalline thin films was found to be partially reversible upon rupture of the film. In conclusion, conventional deformation mechanisms are still active in nanocrystalline metals but with different weighting as compared with conventional materials with coarser grains. PMID:27335747

  3. In situ observation and measurement of composites subjected to extremely high temperature

    NASA Astrophysics Data System (ADS)

    Fang, Xufei; Yu, Helong; Zhang, Guobing; Su, Hengqiang; Tang, Hongxiang; Feng, Xue

    2014-03-01

    In this work, we develop an instrument to study the ablation and oxidation process of materials such as C/SiC (carbon fiber reinforced silicon carbide composites) and ultra-high temperature ceramic in extremely high temperature environment. The instrument is integrated with high speed cameras with filtering lens, infrared thermometers and water vapor generator for image capture, temperature measurement, and humid atmosphere, respectively. The ablation process and thermal shock as well as the temperature on both sides of the specimen can be in situ monitored. The results show clearly the dynamic ablation and liquid oxide flowing. In addition, we develop an algorithm for the post-processing of the captured images to obtain the deformation of the specimens, in order to better understand the behavior of the specimen subjected to high temperature.

  4. In situ observation and measurement of composites subjected to extremely high temperature.

    PubMed

    Fang, Xufei; Yu, Helong; Zhang, Guobing; Su, Hengqiang; Tang, Hongxiang; Feng, Xue

    2014-03-01

    In this work, we develop an instrument to study the ablation and oxidation process of materials such as C/SiC (carbon fiber reinforced silicon carbide composites) and ultra-high temperature ceramic in extremely high temperature environment. The instrument is integrated with high speed cameras with filtering lens, infrared thermometers and water vapor generator for image capture, temperature measurement, and humid atmosphere, respectively. The ablation process and thermal shock as well as the temperature on both sides of the specimen can be in situ monitored. The results show clearly the dynamic ablation and liquid oxide flowing. In addition, we develop an algorithm for the post-processing of the captured images to obtain the deformation of the specimens, in order to better understand the behavior of the specimen subjected to high temperature.

  5. Coalescence and sintering of Pt nanoparticles: in situ observation by aberration-corrected HAADF STEM.

    PubMed

    Asoro, M A; Kovar, D; Shao-Horn, Y; Allard, L F; Ferreira, P J

    2010-01-15

    An aberration-corrected JEOL 2200FS scanning-transmission electron microscope (STEM), equipped with a high-angle annular dark-field detector (HAADF), is used to monitor the coalescence and sintering of Pt nanoparticles with an average diameter of 2.8 nm. This in situ STEM capability is combined with an analysis methodology that together allows direct measurements of mass transport phenomena that are important in understanding how particle size influences coalescence and sintering at the nanoscale. To demonstrate the feasibility of this methodology, the surface diffusivity is determined from measurements obtained from STEM images acquired during the initial stages of sintering. The measured surface diffusivities are in reasonable agreement with measurements made on the surface of nanoparticles, using other techniques. In addition, the grain boundary mobility is determined from measurements made during the latter stages of sintering. PMID:19955618

  6. Coalescence and sintering of Pt nanoparticles: in situ observation by aberration-corrected HAADF STEM

    NASA Astrophysics Data System (ADS)

    Asoro, M. A.; Kovar, D.; Shao-Horn, Y.; Allard, L. F.; Ferreira, P. J.

    2010-01-01

    An aberration-corrected JEOL 2200FS scanning-transmission electron microscope (STEM), equipped with a high-angle annular dark-field detector (HAADF), is used to monitor the coalescence and sintering of Pt nanoparticles with an average diameter of 2.8 nm. This in situ STEM capability is combined with an analysis methodology that together allows direct measurements of mass transport phenomena that are important in understanding how particle size influences coalescence and sintering at the nanoscale. To demonstrate the feasibility of this methodology, the surface diffusivity is determined from measurements obtained from STEM images acquired during the initial stages of sintering. The measured surface diffusivities are in reasonable agreement with measurements made on the surface of nanoparticles, using other techniques. In addition, the grain boundary mobility is determined from measurements made during the latter stages of sintering.

  7. In situ atomic-scale observation of continuous and reversible lattice deformation beyond the elastic limit

    PubMed Central

    Wang, Lihua; Liu, Pan; Guan, Pengfei; Yang, Mingjie; Sun, Jialin; Cheng, Yongqiang; Hirata, Akihiko; Zhang, Ze; Ma, Evan; Chen, Mingwei; Han, Xiaodong

    2013-01-01

    The elastic strain sustainable in crystal lattices is usually limited by the onset of inelastic yielding mediated by discrete dislocation activity, displacive deformation twinning and stress-induced phase transformations, or fracture associated with flaws. Here we report a continuous and gradual lattice deformation in bending nickel nanowires to a reversible shear strain as high as 34.6%, which is approximately four times that of the theoretical elastic strain limit for unconstrained loading. The functioning deformation mechanism was revealed on the atomic scale by an in situ nanowire bending experiments inside a transmission electron microscope. The complete continuous lattice straining process of crystals has been witnessed in its entirety for the straining path, which starts from the face-centred cubic lattice, transitions through the orthogonal path to reach a body-centred tetragonal structure and finally to a re-oriented face-centred cubic structure. PMID:24022231

  8. In situ observation of heat-induced degradation of perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Divitini, G.; Cacovich, S.; Matteocci, F.; Cinà, L.; di Carlo, A.; Ducati, C.

    2016-02-01

    The lack of thermal stability of perovskite solar cells is hindering the progress of this technology towards adoption in the consumer market. Different pathways of thermal degradation are activated at different temperatures in these complex nanostructured hybrid composites. Thus, it is essential to explore the thermal response of the mesosuperstructured composite device to engineer materials and operating protocols. Here we produce devices according to four well-established recipes, and characterize their photovoltaic performance as they are heated within the operational range. The devices are analysed using transmission electron microscopy as they are further heated in situ, to monitor changes in morphology and chemical composition. We identify mechanisms for structural and chemical changes, such as iodine and lead migration, which appear to be correlated to the synthesis conditions. In particular, we identify a correlation between exposure of the perovskite layer to air during processing and elemental diffusion during thermal treatment.

  9. In situ observations of dissolved iron and manganese in hydrothermal vent plumes, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Chin, Carol S.; Coale, Kenneth H.; Elrod, Virginia A.; Johnson, Kenneth S.; Massoth, Gary J.; Baker, Edward T.

    1994-03-01

    In situ mesaurements of dissolved manganese and total dissolved iron were conducted in hydrothermal plumes over the Juan de Fuca Ridge using a submersible chemical analyzer (Scanner). The Scanner was deployed as part of a conductivity, temperature, depth (CTD)/transmissometer rosette instrument package on both tow-yos and vertical casts during the VENTS Leg I cruise in 1989. Dissolved manganese and total dissolved iron concentrations, along with temperature and light attenuation anomalies, were determined over the ridge crest every 5 s. Discrete samples for laboratory analyses of dissolved iron II, total dissolved iron II+III and manganese were also collected. Metal to heat ratios (Me:Q) measured in situ were extremely variable in one steady state plume, while an event plume had constant Me:Q. Uniform values of Mn:Q in the event plume demonstrate that Mn behaves conservatively in the near-field plume. Variability in the Mn:Q ratios in a steady state plume indicated the presence of at least two hydrothermal sources with distinct Me:Q values. A simple mixing model shows that the contribution of Mn from high Me:Q sources, with a composition characteristic of black smoker vents, varies between 1% and 99% within the core of the steady state plume with an average value of 55%. On average, over 50% of the excess heat within the plume originates from low Me:Q ratio sources, with a composition characteristic of low-temperature, diffuse flow vent fluids. Less than 4% of the volume of hydrothermal fluids in the plume originates from black smokers. The Fe II concentrations were used to provide an estimate of plume age on a transect across the ridge axis. Plume ages were about 2.5 days on axis and greater than 12 days off axis. These plume ages were modeled to provide estimates of plume transport and horizontal diffusion and show excellent agreement with ages determined using Rn-222.

  10. In situ observations of the isotopic composition of methane at the Cabauw tall tower site

    NASA Astrophysics Data System (ADS)

    Röckmann, Thomas; Eyer, Simon; van der Veen, Carina; Popa, Maria E.; Tuzson, Béla; Monteil, Guillaume; Houweling, Sander; Harris, Eliza; Brunner, Dominik; Fischer, Hubertus; Zazzeri, Giulia; Lowry, David; Nisbet, Euan G.; Brand, Willi A.; Necki, Jaroslav M.; Emmenegger, Lukas; Mohn, Joachim

    2016-08-01

    High-precision analyses of the isotopic composition of methane in ambient air can potentially be used to discriminate between different source categories. Due to the complexity of isotope ratio measurements, such analyses have generally been performed in the laboratory on air samples collected in the field. This poses a limitation on the temporal resolution at which the isotopic composition can be monitored with reasonable logistical effort. Here we present the performance of a dual isotope ratio mass spectrometric system (IRMS) and a quantum cascade laser absorption spectroscopy (QCLAS)-based technique for in situ analysis of the isotopic composition of methane under field conditions. Both systems were deployed at the Cabauw Experimental Site for Atmospheric Research (CESAR) in the Netherlands and performed in situ, high-frequency (approx. hourly) measurements for a period of more than 5 months. The IRMS and QCLAS instruments were in excellent agreement with a slight systematic offset of (+0.25 ± 0.04) ‰ for δ13C and (-4.3 ± 0.4) ‰ for δD. This was corrected for, yielding a combined dataset with more than 2500 measurements of both δ13C and δD. The high-precision and high-temporal-resolution dataset not only reveals the overwhelming contribution of isotopically depleted agricultural CH4 emissions from ruminants at the Cabauw site but also allows the identification of specific events with elevated contributions from more enriched sources such as natural gas and landfills. The final dataset was compared to model calculations using the global model TM5 and the mesoscale model FLEXPART-COSMO. The results of both models agree better with the measurements when the TNO-MACC emission inventory is used in the models than when the EDGAR inventory is used. This suggests that high-resolution isotope measurements have the potential to further constrain the methane budget when they are performed at multiple sites that are representative for the entire European domain.

  11. Connecting white light to in situ observations of 22 coronal mass ejections from the Sun to 1 AU

    NASA Astrophysics Data System (ADS)

    Moestl, C.; Amla, K.; Farrugia, C. J.; Hall, J. R.; Liewer, P. C.; De Jong, E.; Colaninno, R. C.; Vourlidas, A.; Veronig, A. M.; Rollett, T.; Temmer, M.; Peinhart, V.; Davies, J.; Lugaz, N.; Liu, Y. D.; McEnulty, T.; Luhmann, J. G.; Galvin, A. B.

    2013-12-01

    We study the feasibility of using a Heliospheric Imager (HI) instrument, such as STEREO/HI, for unambiguously connecting remote images to in situ observations of coronal mass ejection (CMEs). Our goal is to develop and test methods to predict CME parameters from heliospheric images, but our dataset can actually be used to benchmark any ICME propagation model. The results are of interest concerning future missions such as Solar Orbiter, or a dedicated space weather mission at the Sun-Earth L5 point (e.g. EASCO mission concept). We compare the predictions for speed and arrival time for 22 CME events (between 2008-2012), each observed remotely by one STEREO spacecraft, to the interplanetary coronal mass ejection (ICME) speed and arrival time observed at in situ observatories (STEREO PLASTIC/IMPACT, Wind SWE/MFI). We use forward modeling for STEREO-COR2, and geometrical models for STEREO-HII, assuming different CME front shapes (Fixed-Phi, Harmonic Mean, Self-similar expansion), and fit them to the CME time-elongation functions with the SolarSoft SATPLOT tool, assuming constant CME speed and direction. The arrival times derived from imaging match the in situ ones +/- 8 hours, and speeds are consistent within +/-300 km/s, including CME apex/flank effects. We find no preference in the predictive capability for any of the 3 geometries used on the full dataset, consisting of front- and backsided, slow and fast CMEs (up to 2700 km/s). We search for new empirical relations between the predicted and observed speeds and arrival times, enhancing the HI predictive capabilities. Additionally, for very fast and back-sided CMEs, strong differences between the results of the HI models arise, consistent with theoretical expectations by Lugaz and Kintner (2013, Solar Physics). This work has received funding from the European Commission FP7 Project COMESEP (263252).

  12. The Sodankylä in situ soil moisture observation network: an example application of ESA CCI soil moisture product evaluation

    NASA Astrophysics Data System (ADS)

    Ikonen, Jaakko; Vehviläinen, Juho; Rautiainen, Kimmo; Smolander, Tuomo; Lemmetyinen, Juha; Bircher, Simone; Pulliainen, Jouni

    2016-04-01

    During the last decade there has been considerable development in remote sensing techniques relating to soil moisture retrievals over large areas. Within the framework of the European Space Agency's (ESA) Climate Change Initiative (CCI) a new soil moisture product has been generated, merging different satellite-based surface soil moisture based products. Such remotely sensed data need to be validated by means of in situ observations in different climatic regions. In that context, a comprehensive, distributed network of in situ measurement stations gathering information on soil moisture, as well as soil temperature, has been set up in recent years at the Finnish Meteorological Institute's (FMI) Sodankylä Arctic research station. The network forms a calibration and validation (CAL-VAL) reference site and is used as a tool to evaluate the validity of satellite retrievals of soil properties. In this paper we present the Sodankylä CAL-VAL reference site soil moisture observation network, its instrumentation as well as its areal representativeness over the study area and the region in general as a whole. As an example of data utilization, comparisons of spatially weighted average top-layer soil moisture observations between the years 2012 and 2014 against ESA CCI soil moisture data product estimates are presented and discussed. The comparisons were made against a single ESA CCI data product pixel encapsulating most of the Sodankylä CAL-VAL network sites. Comparisons are made with daily averaged and running weekly averaged soil moisture data as well as through application of an exponential soil moisture filter. The overall achieved correlation between the ESA CCI data product and in situ observations varies considerably (from 0.479 to 0.637) depending on the applied comparison perspective. Similarly, depending on the comparison perspective used, inter-annual correlation comparison results exhibit even more pronounced variation, ranging from 0.166 to 0.840.

  13. Biooptical variability in the Greenland Sea observed with the Multispectral Airborne Radiometer System (MARS)

    NASA Technical Reports Server (NTRS)

    Mueller, James L.; Trees, Charles C.

    1989-01-01

    A site-specific ocean color remote sensing algorithm was developed and used to convert Multispectral Airborne Radiometer System (MARS) spectral radiance measurements to chlorophyll-a concentration profiles along aircraft tracklines in the Greenland Sea. The analysis is described and the results given in graphical or tabular form. Section 2 describes the salient characteristics and history of development of the MARS instrument. Section 3 describes the analyses of MARS flight segments over consolidated sea ice, resulting in a set of altitude dependent ratios used (over water) to estimate radiance reflected by the surface and atmosphere from total radiance measured. Section 4 presents optically weighted pigment concentrations calculated from profile data, and spectral reflectances measured in situ from the top meter of the water column; this data was analyzed to develop an algorithm relating chlorophyll-a concentrations to the ratio of radiance reflectances at 441 and 550 nm (with a selection of coefficients dependent upon whether significant gelvin presence is implied by a low ratio of reflectances at 410 and 550 nm). Section 5 describes the scaling adjustments which were derived to reconcile the MARS upwelled radiance ratios at 410:550 nm and 441:550 nm to in situ reflectance ratios measured simultaneously on the surface. Section 6 graphically presents the locations of MARS data tracklines and positions of the surface monitoring R/V. Section 7 presents stick-plots of MARS tracklines selected to illustrate two-dimensional spatial variability within the box covered by each day's flight. Section 8 presents curves of chlorophyll-a concentration profiles derived from MARS data along survey tracklines. Significant results are summarized in Section 1.

  14. Case Studies for UV, O2-A Band and Polarimetric Airborne Remote Sensing Observations of Coastal Waters: Implications for Atmospheric Correction.

    NASA Astrophysics Data System (ADS)

    Chowdhary, J.; van Diedenhoven, B.; Knobelspiesse, K. D.; Cairns, B.; Wasilewski, A. P.; Mccubbin, I. B.

    2014-12-01

    A major challenge for spaceborne observations of ocean color is to correct for atmospheric scattering, which typically contributes ≥85% to the top-of-atmosphere (TOA) radiance and varies substantially with aerosols. Ocean color missions traditionally analyze TOA radiance in the near-infrared (NIR), where the ocean is black, to constrain the TOA atmospheric scattering in the visible (VIS). However, this procedure is limited by insufficient sensitivity of NIR radiance to absorption and vertical distribution of aerosols, and by uncertainties in the extrapolation of aerosol properties from the NIR to the VIS. To improve atmospheric correction for ocean color observations, one needs to change the traditional procedure for this correction and/or increase the aerosol information. The instruments proposed for the Pre-Aerosol, Clouds, and ocean Ecosystem (PACE) mission include ultraviolet and Oxygen A-band observations, as well as multispectral and multiangle polarimetry, to increase the aerosol information content. However no studies have been performed on whether such observations contain sufficient aerosol information, and on how to use this information, to substantially improve atmospheric correction. To study the atmospheric correction capabilities of PACE-like instruments, we are conducting field experiments off the Coast of California to obtain high-altitude airborne and in-situ observations of water-leaving radiance. The airborne data sets consist of hyperspectral radiance between 380-2500 nm by the Airborne Visible/Infrared Imaging Spectrometer, and narrow-band multiangle polarimetric data between 410-2250 nm by the Research Scanning Polarimeter. We discuss the quality of and comparisons between these data sets, and their differential sensitivities to variations in aerosol properties and ocean color.

  15. Source attribution using FLEXPART and carbon monoxide emission inventories for the IAGOS In-situ Observation database

    NASA Astrophysics Data System (ADS)

    Fontaine, Alain; Sauvage, Bastien; Pétetin, Hervé; Auby, Antoine; Boulanger, Damien; Thouret, Valerie

    2016-04-01

    Since 1994, the IAGOS program (In-Service Aircraft for a Global Observing System http://www.iagos.org) and its predecessor MOZAIC has produced in-situ measurements of the atmospheric composition during more than 46000 commercial aircraft flights. In order to help analyzing these observations and further understanding the processes driving their evolution, we developed a modelling tool SOFT-IO quantifying their source/receptor link. We improved the methodology used by Stohl et al. (2003), based on the FLEXPART plume dispersion model, to simulate the contributions of anthropogenic and biomass burning emissions from the ECCAD database (http://eccad.aeris-data.fr) to the measured carbon monoxide mixing ratio along each IAGOS flight. Thanks to automated processes, contributions are simulated for the last 20 days before observation, separating individual contributions from the different source regions. The main goal is to supply add-value products to the IAGOS database showing pollutants geographical origin and emission type. Using this information, it may be possible to link trends in the atmospheric composition to changes in the transport pathways and to the evolution of emissions. This tool could be used for statistical validation as well as for inter-comparisons of emission inventories using large amounts of data, as Lagrangian models are able to bring the global scale emissions down to a smaller scale, where they can be directly compared to the in-situ observations from the IAGOS database.

  16. A three-dimensional characterization of Arctic aerosols from airborne Sun photometer observations: PAM-ARCMIP, April 2009

    NASA Astrophysics Data System (ADS)

    Stone, R. S.; Herber, A.; Vitale, V.; Mazzola, M.; Lupi, A.; Schnell, R. C.; Dutton, E. G.; Liu, P. S. K.; Li, S.-M.; Dethloff, K.; Lampert, A.; Ritter, C.; Stock, M.; Neuber, R.; Maturilli, M.

    2010-07-01

    The Arctic climate is modulated, in part, by atmospheric aerosols that affect the distribution of radiant energy passing through the atmosphere. Aerosols affect the surface-atmosphere radiation balance directly through interactions with solar and terrestrial radiation and indirectly through interactions with cloud particles. Better quantification of the radiative forcing by different types of aerosol is needed to improve predictions of future climate. During April 2009, the airborne campaign Pan-Arctic Measurements and Arctic Regional Climate Model Inter-comparison Project (PAM-ARCMIP) was conducted. The mission was organized by Alfred Wegener Institute for Polar and Marine Research of Germany and utilized their research aircraft, Polar-5. The goal was to obtain a snapshot of surface and atmospheric conditions over the central Arctic prior to the onset of the melt season. Characterizing aerosols was one objective of the campaign. Standard Sun photometric procedures were adopted to quantify aerosol optical depth AOD, providing a three-dimensional view of the aerosol, which was primarily haze from anthropogenic sources. Independent, in situ measurements of particle size distribution and light extinction, derived from airborne lidar, are used to corroborate inferences made using the AOD results. During April 2009, from the European to the Alaskan Arctic, from sub-Arctic latitudes to near the pole, the atmosphere was variably hazy with total column AOD at 500 nm ranging from ˜0.12 to >0.35, values that are anomalously high compared with previous years. The haze, transported primarily from Eurasian industrial regions, was concentrated within and just above the surface-based temperature inversion layer. Extinction, as measured using an onboard lidar system, was also greatest at low levels, where particles tended to be slightly larger than at upper levels. Black carbon (BC) (soot) was observed at all levels sampled, but at moderate to low concentrations compared with

  17. Deriving an atmospheric budget of total organic bromine using airborne in-situ measurements of brominated hydrocarbons in the Western Pacific during SHIVA

    NASA Astrophysics Data System (ADS)

    Sala, Stephan; Bönisch, Harald; Keber, Timo; Oram, Dave; Mills, Graham; Engel, Andreas

    2014-05-01

    Halogenated hydrocarbons play a major role as precursors for stratospheric ozone depletion. Released from the surface in the troposphere, the halocarbons reach the stratosphere via transport through the tropical tropopause layer. The contribution of the so called very short lived species (VSLS), having atmospheric lifetimes of less than half a year as sources gases for stratospheric bromine is significant. Source gas observations of long-lived bromine compounds and VSLS have so far not been able to explain the amount of bromine derived in the stratosphere from observations of BrO and modeling of the ratio of BrO to total bromine. Due to the short lifetimes and the high atmospheric variability, the representativeness of the available observations of VSLS source gases remains unclear, as these may vary with region and display seasonal variability. During the SHIVA (Stratospheric Ozone: Halogen Impacts in a Varying Atmosphere) project an extensive dataset with over 700 samples of ambient air of all halogen species relevant for the atmospheric budget of total organic bromine (long lived halocarbons: H-1301, H-1211, H-1202, H-2402 and CH3Br, very short lived substances: CHBr3, CH2Br2, CHBr2Cl, CHBrCl2 and CHBrCl) have been collected from onboard the FALCON aircraft in the West Pacific region. Measurements were performed with the newly developed fully-automated in-situ instrument GHOST-MS (Gas chromatograph for the Observation of Tracers - coupled with a Mass Spectrometer) by the Goethe University of Frankfurt and with the onboard whole-air sampler WASP with subsequent ground based state-of-the-art GC/MS analysis by the University of East Anglia. We will present the datasets, compare these to other observation, derive a bromine budget for the West Pacific and derive an estimate of the amount of bromine from VSLS reaching the stratosphere. Using the mean mixing ratios in the upper troposphere of the halocarbons mentioned above, the calculated budget of the total organic

  18. In situ observations of black carbon in snow and the corresponding spectral surface albedo reduction

    NASA Astrophysics Data System (ADS)

    Pedersen, C. A.; Gallet, J.-C.; Ström, J.; Gerland, S.; Hudson, S. R.; Forsström, S.; Isaksson, E.; Berntsen, T. K.

    2015-02-01

    Black carbon (BC) particles emitted from incomplete combustion of fossil fuel and biomass and deposited on snow and ice darken the surface and reduce the surface albedo. Even small initial surface albedo reductions may have larger adjusted effects due to snow morphology changes and changes in the sublimation and snow melt rate. Most of the literature on the effect of BC on snow surface albedo is based on numerical models, and few in situ field measurements exist to confirm this reduction. Here we present an extensive set of concurrent in situ measurements of spectral surface albedo, BC concentrations in the upper 5 cm of the snowpack, snow physical parameters (grain size and depth), and incident solar flux characteristics from the Arctic. From this data set (with median BC concentrations ranging from 5 to 137 ng BC per gram of snow) we are able to separate the BC signature on the snow albedo from the natural snow variability. Our measurements show a significant correlation between BC in snow and spectral surface albedo. Based on these measurements, parameterizations are provided, relating the snow albedo, as a function of wavelength, to the equivalent BC content in the snowpack. The term equivalent BC used here is the elemental carbon concentration inferred from the thermo-optical method adjusted for the fraction of non-BC constituents absorbing sunlight in the snow. The first parameterization is a simple equation which efficiently describes the snow albedo reduction due to the equivalent BC without including details on the snow or BC microphysics. This can be used in models when a simplified description is needed. A second parameterization, including snow grain size information, shows enhanced correspondence with the measurements. The extracted parameterizations are valid for wavelength bands 400-900 nm, constrained for BC concentrations between 1 and 400 ng g-1, and for an optically thick snowpack. The parameterizations are purely empirical, and particular focus

  19. In-situ observation of nickel oxidation using synchrotron based full-field transmission X-ray microscopy

    NASA Astrophysics Data System (ADS)

    Kiss, Andrew M.; Harris, William M.; Wang, Steve; Vila-Comamala, Joan; Deriy, Alex; Chiu, Wilson K. S.

    2013-02-01

    An in situ imaging-based approach is reported to study chemical reactions using full-field transmission x-ray microscopy (TXM). Ni particles were oxidized at temperatures between 400 and 850 °C in the TXM to directly observe their morphology change while the chemical composition is monitored by x-ray absorption near edge spectroscopy. Reaction rates and activation energies are calculated from the image data. The goal of this effort is to better understand Ni oxidation in electrode materials. The approach developed will be an effective technique for directly studying chemical reactions of particles and their behavior at the nano-scale.

  20. Lithium Electrodeposition Dynamics in Aprotic Electrolyte Observed in Situ via Transmission Electron Microscopy.

    PubMed

    Leenheer, Andrew J; Jungjohann, Katherine L; Zavadil, Kevin R; Sullivan, John P; Harris, C Thomas

    2015-04-28

    Electrodeposited metallic lithium is an ideal negative battery electrode, but nonuniform microstructure evolution during cycling leads to degradation and safety issues. A better understanding of the Li plating and stripping processes is needed to enable practical Li-metal batteries. Here we use a custom microfabricated, sealed liquid cell for in situ scanning transmission electron microscopy (STEM) to image the first few cycles of lithium electrodeposition/dissolution in liquid aprotic electrolyte at submicron resolution. Cycling at current densities from 1 to 25 mA/cm(2) leads to variations in grain structure, with higher current densities giving a more needle-like, higher surface area deposit. The effect of the electron beam was explored, and it was found that, even with minimal beam exposure, beam-induced surface film formation could alter the Li microstructure. The electrochemical dissolution was seen to initiate from isolated points on grains rather than uniformly across the Li surface, due to the stabilizing solid electrolyte interphase surface film. We discuss the implications for operando STEM liquid-cell imaging and Li-battery applications.

  1. Coordinated in-situ observation of developing hurricanes using atmospheric balloons - a Model Predictive Control approach

    NASA Astrophysics Data System (ADS)

    Meneghello, Gianluca; Bewley, Thomas

    2014-11-01

    Current operational methods used to monitor the development of hurricanes and typhoons include radar and satellite imagery as well as dropsondes parachuted from repeated aircraft flights above the hurricane itself. The accurate in-situ measurements provided by dropsondes are especially valuable for generating an accurate forecast of a hurricane's evolution and landfall. Unfortunately, the data from dropsondes is expensive to obtain (requiring many hazardous high-altitude flights) and limited both spatially (to the vertical profile of its path) and temporally (to the ten or twenty minutes it takes to fall). We show in the present work how receding-horizon MPC can be used to coordinate a formation of sensor-laden atmospheric balloons, distributing them quasi-uniformly across a realistic developing hurricane flowfield for days at a time. Several atmospheric balloons can be released from a high-altitude aircraft, or launched from a ship at sea level, and distributed over the hurricane thereafter. Certain target orbits of interest in the hurricane can be continuously sampled by some balloons, while other balloons make continuous sweeps between the eye and the spiral rain bands. Various solution methods for the optimal control problem arising within the MPC framework are considered.

  2. Lithium electrodeposition dynamics in aprotic electrolyte observed in situ via transmission electron microscopy

    DOE PAGES

    Leenheer, Andrew Jay; Jungjohann, Katherine Leigh; Zavadil, Kevin Robert; Sullivan, John P.; Harris, Charles Thomas

    2015-03-18

    Electrodeposited metallic lithium is an ideal negative battery electrode, but nonuniform microstructure evolution during cycling leads to degradation and safety issues. A better understanding of the Li plating and stripping processes is needed to enable practical Li-metal batteries. Here we use a custom microfabricated, sealed liquid cell for in situ scanning transmission electron microscopy (STEM) to image the first few cycles of lithium electrodeposition/dissolution in liquid aprotic electrolyte at submicron resolution. Cycling at current densities from 1 to 25 mA/cm2 leads to variations in grain structure, with higher current densities giving a more needle-like, higher surface area deposit. The effectmore » of the electron beam was explored, and it was found that, even with minimal beam exposure, beam-induced surface film formation could alter the Li microstructure. The electrochemical dissolution was seen to initiate from isolated points on grains rather than uniformly across the Li surface, due to the stabilizing solid electrolyte interphase surface film. As a result, we discuss the implications for operando STEM liquid-cell imaging and Li-battery applications.« less

  3. In situ SEM observation of microscale strain fields around a crack tip in polycrystalline molybdenum

    NASA Astrophysics Data System (ADS)

    Li, J. J.; Li, W. C.; Jin, Y. J.; Wang, L. F.; Zhao, C. W.; Xing, Y. M.; Lang, F. C.; Yan, L.; Yang, S. T.

    2016-06-01

    In situ scanning electron microscopy was employed to investigate the crack initiation and propagation in polycrystalline molybdenum under uniaxial tensile load at room temperature. The microscale grid pattern was fabricated using the sputtering deposition technology on the specimen surface covered with a fine square mesh copper grid. The microscale strain fields around the crack tip were measured by geometric phase analysis technique and compared with the theoretical solutions based on the linear elastic fracture mechanics theory. The results showed that as the displacement increases, the crack propagated mainly perpendicular to the tensile direction during the fracture process of molybdenum. The normal strain ɛ xx and shear strain ɛ xy are relatively small, and the normal strain ɛ yy holds a dominant position in the deformation fields and plays a key role in the whole fracture process of molybdenum. With the increase in displacement, the ɛ yy increases rapidly and the two lobes grow significantly but maintain the same shape and orientation. The experimental ɛ yy is in agreement with the theoretical solution. Along the x-axis in front of the crack tip, there is minor discrepancy between the experimental ɛ yy and theoretical ɛ yy within 25 μm from the crack tip, but the agreement between them is very good far from the crack tip (>25 μm).

  4. Time Resolved Nucleation and Growth of Monodisperse FeOOH Nanoparticles Observed in situ

    NASA Astrophysics Data System (ADS)

    Legg, B. A.; Zhu, M.; Zhang, H.; Waychunas, G.; Banfield, J. F.

    2012-12-01

    The nucleation and growth of oxide minerals from aqueous solution is a poorly understood process. Complexities such as two-stage precipitation, phase transformation, and hydrolysis often inhibit simple interpretation. In this study, we track the thermally induced nucleation and growth of akaganeite (β-FeOOH) nanoparticles from FeCl3 solutions, using in situ time resolved small angle x-ray scattering (SAXS) and transmission electron microscopy (TEM). Variations in reaction temperature (from 37 deg C to 80 deg C) and FeCl3 concentration (from 5 mM to 800 mM) produce systematic changes in nucleation rate, growth rate, particle size distribution, and aspect ratio. Low FeCl3 concentrations and high temperatures lead to formation of very small particles via rapid nucleation. (FeCl3 solutions are actually more supersaturated with respect to akaganeite when concentrations are low, due to the acid-base chemistry of ferric iron.) Increasing the FeCl3 concentration leads to large, highly monodisperse particles via size focused growth. Suspensions of highly monodisperse, elongated particles are found to self-organize into two dimensional colloidal crystals. The well-controlled growth processes in this system make it possible to conduct detailed kinetic modeling, and determine how both nucleation and growth rate respond to changes in the experimental conditions.

  5. An in situ method for observing wax crystallization under pipe flow

    NASA Astrophysics Data System (ADS)

    Welch, Sarah E.; Mazzanti, Gianfranco; Steer, Tyrone N.; Stetzer, Mackenzie R.; Kautsky, Sacha P.; Merz, Hugh; Idziak, Stefan H. J.; Sirota, Eric B.

    2003-03-01

    As the phenomenon of wax deposition in crude oil pipelines is of great relevance to the petroleum industry, there has been considerable work on both real and model oil pipeline systems in an effort to gain insight into the deposition process itself. In an effort to develop a truly in situ means of characterizing the formation and evolution of the wax gel layers deposited in model pipeline systems, we have performed x-ray diffraction measurements of wax crystallization in wax-oil mixtures under flow. We conducted a time dependent investigation of the nucleation and growth of wax crystals and the evolution of the resulting wax gel deposit in mixtures of paraffin wax and dodecane under pipe flow through a standard x-ray quartz capillary of diameter 1mm. Our results were compared with those of larger scale, pressure drop experiments[1]. 1. Singh, P., et al., Formation and Aging of Incipient Thin Film Wax-Oil Gels. American Institute of Chemical Engineers Journal, 2000. 46(5): p. 1059-1074.

  6. In Situ Observation of Gypsum-Anhydrite Transition at High Pressure and High Temperature

    NASA Astrophysics Data System (ADS)

    Liu, Chuan-Jiang; Zheng, Hai-Fei

    2012-04-01

    An in-situ Raman spectroscopic study of gypsum-anhydrite transition under a saturated water condition at high pressure and high temperature is performed using a hydrothermal diamond anvil cell (HDAC). The experimental results show that gypsum dissolvs in water at ambient temperature and above 496 MPa. With increasing temperature, the anhydrite (CaSO4) phase precipitates at 250-320°C in the pressure range of 1.0-1.5GPa, indicating that under a saturated water condition, both stable conditions of pressure and temperature and high levels of Ca and SO4 ion concentrations in aqueous solution are essential for the formation of anhydrite. A linear relationship between the pressure and temperature for the precipitation of anhydrite is established as P(GPa) = 0.0068T-0.7126 (250°C<=T<=320°C). Anhydrite remained stable during rapid cooling of the sample chamber, showing that the gypsum-anhydrite transition involving both dissolution and precipitation processes is irreversible at high pressure and high temperature.

  7. Seasonal variability of the Red Sea, from satellite gravity, radar altimetry, and in situ observations

    NASA Astrophysics Data System (ADS)

    Wahr, John; Smeed, David A.; Leuliette, Eric; Swenson, Sean

    2014-08-01

    Seasonal variations of sea surface height (SSH) and mass within the Red Sea are caused mostly by exchange of heat with the atmosphere and by flow through the strait opening into the Gulf of Aden to the south. That flow involves a net mass transfer into the Red Sea during fall and out during spring, though in summer there is an influx of cool water at intermediate depths. Thus, summer water in the south is warmer near the surface due to higher air temperatures, but cooler at intermediate depths. Summer water in the north experiences warming by air-sea exchange only. The temperature affects water density, which impacts SSH but has no effect on mass. We study this seasonal cycle by combining GRACE mass estimates, altimeter SSH measurements, and steric contributions derived from the World Ocean Atlas temperature climatology. Among our conclusions are: mass contributions are much larger than steric contributions; the mass is largest in winter, consistent with winds pushing water into the Red Sea in fall and out during spring; the steric signal is largest in summer, consistent with surface warming; and the cool, intermediate-depth water flowing into the Red Sea in spring has little impact on the steric signal, because contributions from the lowered temperature are offset by effects of decreased salinity. The results suggest that the combined use of altimeter and GRACE measurements can provide a useful alternative to in situ data for monitoring the steric signal.

  8. Lithium Electrodeposition Dynamics in Aprotic Electrolyte Observed in Situ via Transmission Electron Microscopy.

    PubMed

    Leenheer, Andrew J; Jungjohann, Katherine L; Zavadil, Kevin R; Sullivan, John P; Harris, C Thomas

    2015-04-28

    Electrodeposited metallic lithium is an ideal negative battery electrode, but nonuniform microstructure evolution during cycling leads to degradation and safety issues. A better understanding of the Li plating and stripping processes is needed to enable practical Li-metal batteries. Here we use a custom microfabricated, sealed liquid cell for in situ scanning transmission electron microscopy (STEM) to image the first few cycles of lithium electrodeposition/dissolution in liquid aprotic electrolyte at submicron resolution. Cycling at current densities from 1 to 25 mA/cm(2) leads to variations in grain structure, with higher current densities giving a more needle-like, higher surface area deposit. The effect of the electron beam was explored, and it was found that, even with minimal beam exposure, beam-induced surface film formation could alter the Li microstructure. The electrochemical dissolution was seen to initiate from isolated points on grains rather than uniformly across the Li surface, due to the stabilizing solid electrolyte interphase surface film. We discuss the implications for operando STEM liquid-cell imaging and Li-battery applications. PMID:25785517

  9. A knowledge-based expert system for scheduling of airborne astronomical observations

    NASA Technical Reports Server (NTRS)

    Nachtsheim, P. R.; Gevarter, W. B.; Stutz, J. C.; Banda, C. P.

    1985-01-01

    The Kuiper Airborne Observatory Scheduler (KAOS) is a knowledge-based expert system developed at NASA Ames Research Center to assist in route planning of a C-141 flying astronomical observatory. This program determines a sequence of flight legs that enables sequential observations of a set of heavenly bodies derived from a list of desirable objects. The possible flight legs are constrained by problems of observability, avoiding flyovers of warning and restricted military zones, and running out of fuel. A significant contribution of the KAOS program is that it couples computational capability with a reasoning system.

  10. Turbulence and Mountain Wave Conditions Observed with an Airborne 2-Micron Lidar

    NASA Technical Reports Server (NTRS)

    Teets, Edward H., Jr.; Ehernberger, Jack; Bogue, Rodney; Ashburn, Chris

    2007-01-01

    Joint efforts by the National Aeronautics and Space Administration (NASA), the Department of Defense, and industry partners are enhancing the capability of airborne wind and turbulence detection. The Airborne Coherent Lidar for Advanced In-Flight Measurements (ACLAIM) was flown on three series of flights to assess its capability over a range of altitudes, air mass conditions, and gust phenomena. This paper describes the observation of mountain waves and turbulence induced by mountain waves over the Tehachapi and Sierra Nevada mountain ranges in southern California by lidar onboard the NASA Airborne Science DC-8 airplane. The examples in this paper compare lidar-predicted mountain waves and wave-induced turbulence to subsequent aircraft-measured true airspeed. Airplane acceleration data is presented describing the effects of the wave-induced turbulence on the DC-8 airplane. Highlights of the lidar-predicted airspeed from the two flights show increases of 12 m/s at the mountain wave interface and peak-to-peak airspeed changes of 10 m/s and 15 m/s in a span of 12 s in moderate turbulence.

  11. Turbulence and mountain wave conditions observed with an airborne 2-micron lidar

    NASA Technical Reports Server (NTRS)

    Teets, Edward H., Jr.; Ashburn, Chris; Ehernberger, Jack; Bogue, Rodney

    2006-01-01

    Joint efforts by the National Aeronautics and Space Administration (NASA), the Department of Defense, and industry partners are enhancing the capability of airborne wind and turbulence detection. The Airborne Coherent Lidar for Advanced In-Flight Measurements (ACLAIM) was flown on three series of flights to assess its capability over a range of altitudes, air mass conditions, and gust phenomena. This paper describes the observation of mountain waves and turbulence induced by mountain waves over the Tehachapi and Sierra Nevada mountain ranges (California, USA) by lidar onboard the NASA Airborne Science DC-8 airplane. The examples in this paper compare lidar-predicted mountain waves and wave-induced turbulence to subsequent aircraft-measured true airspeed. Airplane acceleration data is presented describing the effects of the wave-induced turbulence on the DC-8 airplane. Highlights of the lidar-predicted airspeed from the two flights show increases of 12 meters per second (m/s) at the mountain wave interface and peak-to-peak airspeed changes of 10 m/s and 15 m/s in a span of 12 seconds in moderate turbulence.

  12. Turbulence and Mountain Wave Conditions Observed with an Airborne 2-Micron Lidar

    NASA Technical Reports Server (NTRS)

    Teets, Edward H., Jr.; Ashburn, Chris; Ehernberger, L. J.; Bogue, Rodney K.

    2006-01-01

    Joint efforts by the National Aeronautics and Space Administration, the Department of Defense, and industry partners are enhancing the capability of airborne wind and turbulence detection. The Airborne Coherent Lidar (light detection and ranging) for Advanced In-Flight Measurements was flown on three series of flights to assess its capability over a range of altitudes, air mass conditions, and gust phenomena. This report describes the observation of mountain waves and turbulence induced by mountain waves over the Tehachapi and Sierra Nevada mountain ranges by lidar on board the NASA Airborne Science DC-8 (McDonnell Douglas Corporation, Long Beach, California) airplane during two flights. The examples in this report compare lidar-predicted mountain waves and wave-induced turbulence to subsequent airplane-measured true airspeed. Airplane acceleration data is presented describing the effects of the wave-induced turbulence on the DC-8 airplane. Highlights of the lidar-predicted airspeed from the two flights show increases of 12 m/s at the mountain wave interface and peak-to-peak airspeed changes of 10 m/s and 15 m/s in a span of 12 s in moderate turbulence.

  13. In-situ observation of sputtered particles for carbon implanted tungsten during energetic isotope ion implantation

    SciTech Connect

    Oya, Y.; Sato, M.; Uchimura, H.; Okuno, K.; Ashikawa, N.; Sagara, A.; Yoshida, N.; Hatano, Y.

    2015-03-15

    Tungsten is a candidate for plasma facing materials in future fusion reactors. During DT plasma operations, carbon as an impurity will bombard tungsten, leading to the formation of tungsten-carbon (WC) layer and affecting tritium recycling behavior. The effect of carbon implantation for the dynamic recycling of deuterium, which demonstrates tritium recycling, including retention and sputtering, has been investigated using in-situ sputtered particle measurements. The C{sup +} implanted W, WC and HOPG were prepared and dynamic sputtered particles were measured during H{sub 2}{sup +} irradiation. It has been found that the major hydrocarbon species for C{sup +} implanted tungsten is CH{sub 3}, while for WC and HOPG (Highly Oriented Pyrolytic Graphite) it is CH{sub 4}. The chemical state of hydrocarbon is controlled by the H concentration in a W-C mixed layer. The amount of C-H bond and the retention of H trapped by carbon atom should control the chemical form of hydrocarbon sputtered by H{sub 2}{sup +} irradiation and the desorption of CH{sub 3} and CH{sub 2} are due to chemical sputtering, although that for CH is physical sputtering. The activation energy for CH{sub 3} desorption has been estimated to be 0.4 eV, corresponding to the trapping process of hydrogen by carbon through the diffusion in W. It is concluded that the chemical states of hydrocarbon sputtered by H{sub 2}{sup +} irradiation for W is determined by the amount of C-H bond on the W surface. (authors)

  14. In situ observations of suspended particulate matter plumes at an offshore wind farm, southern North Sea

    NASA Astrophysics Data System (ADS)

    Baeye, Matthias; Fettweis, Michael

    2015-08-01

    Suspended particulate matter (SPM) plumes associated with the monopile foundations of the Belgian offshore wind farm (OWF) Belwind I were acoustically profiled by means of a Doppler current profiler (ADCP). Together with the analysis of a bottom lander dataset of optical and acoustic backscatter sensors (OBSs and ADPs respectively), the spatiotemporal SPM plume dynamics were inferred. The fieldwork comprised (1) near-bed measurements of hydrodynamics and SPM concentrations in the direct vicinity of the wind turbines, by means of a bottom lander over a spring-neap cycle in May 2010; this dataset represents a typically tide-driven situation because there was no significant meteorological forcing during the measurement period; (2) additional vessel-based measurements conducted in May 2013 to capture the SPM plumes inside and outside the OWF over part of a tidal cycle. Both in situ datasets revealed that the SPM plumes were generated at the turbine piles, consistent with aerial and space-borne imagery. The SPM plumes are well aligned with the tidal current direction in the wake of the monopiles, concentrations being estimated to reach up to 5 times that of the background concentration of about 3 mg/l. It is suggested that the epifaunal communities colonizing the monopile surface and the protective rock collar at the base play a key role as source of the suspended matter recorded in the plumes. The organisms filter and trap fine SPM from the water column, resulting in predominant accumulation of SPM, including detritus and (pseudo-) faeces, at the base of the piles. When tidal currents exceed a certain velocity, fine particles in the near-bed fluff layer are re-suspended and transported downstream in the wake of the piles.

  15. Airborne Active and Passive L-Band Observations in Soil Moisture Active Passive Validation Experiment 2012 (SMAPVEX12)

    NASA Astrophysics Data System (ADS)

    Colliander, A.; Yueh, S. H.; Chazanoff, S.; Jackson, T. J.; McNairn, H.; Bullock, P.; Wiseman, G.; Berg, A. A.; Magagi, R.; Njoku, E. G.

    2012-12-01

    extensive ground truth collection. In situ soil moisture and vegetation biomass and structure of the mixed cropland, pasture and forest landscape of the experiment domain was gathered synchronously with the airborne acquisitions. The conditions included wide range in both soil moisture and vegetation density. This paper presents an overview of the SMAPVEX12 campaign and an evaluation of the quality of the PALS measurements. The calibration methodology based on the internal calibration, lake over-flights and specific calibration maneuvers were utilized before and after each day's science flights to guarantee accuracy and consistency of the measurements over the campaign duration. As a consequence the correspondence of the airborne acquisitions with the spatial and temporal evolution of the geophysical variables over the experiment domain meets the requirement set by the objectives of the campaign. Acknowledgement: This work was carried out in Jet Propulsion Laboratory, California Institute of Technology under contract with National Aeronautics and Space Administration. USDA is an equal opportunity provider and employer.

  16. Initial results of detected methane emissions from landfills in the Los Angeles Basin during the COMEX campaign by the Methane Airborne MAPper (MAMAP) instrument and a greenhouse gas in-situ analyser

    NASA Astrophysics Data System (ADS)

    Krautwurst, Sven; Gerilowski, Konstantin; Kolyer, Richard; Jonsson, Haflidi; Krings, Thomas; Horstjann, Markus; Leifer, Ira; Vigil, Sam; Buchwitz, Michael; Schüttemeyer, Dirk; Fladeland, Matthew M.; Burrows, John P.; Bovensmann, Heinrich

    2015-04-01

    Methane (CH4) is the second most important anthropogenic greenhouse gas beside carbon dioxide (CO2). Significant contributors to the global methane budget are fugitive emissions from landfills. Due to the growing world population, it is expected that the amount of waste and, therefore, waste disposal sites will increase in number and size in parts of the world, often adjacent growing megacities. Besides bottom-up modelling, a variety of ground based methods (e.g., flux chambers, trace gases, radial plume mapping, etc.) have been used to estimate (top-down) these fugitive emissions. Because landfills usually are large, sometimes with significant topographic relief, vary temporally, and leak/emit heterogeneously across their surface area, assessing total emission strength by ground-based techniques is often difficult. In this work, we show how airborne based remote sensing measurements of the column-averaged dry air mole fraction of CH4 can be utilized to estimate fugitive emissions from landfills in an urban environment by a mass balance approach. Subsequently, these emission rates are compared to airborne in-situ horizontal cross section measurements of CH4 taken within the planetary boundary layer (PBL) upwind and downwind of the landfill at different altitudes immediately after the remote sensing measurements were finished. Additional necessary parameters (e.g., wind direction, wind speed, aerosols, dew point temperature, etc.) for the data inversion are provided by a standard instrumentation suite for atmospheric measurements aboard the aircraft, and nearby ground-based weather stations. These measurements were part of the CO2 and Methane EXperiment (COMEX), which was executed during the summer 2014 in California and was co-funded by the European Space Agency (ESA) and the National Aeronautics and Space Administration (NASA). The remote sensing measurements were taken by the Methane Airborne MAPper (MAMAP) developed and operated by the University of Bremen and

  17. Room Temperature Deformation Mechanisms of Alumina Particles Observed from In Situ Micro-compression and Atomistic Simulations

    NASA Astrophysics Data System (ADS)

    Sarobol, Pylin; Chandross, Michael; Carroll, Jay D.; Mook, William M.; Bufford, Daniel C.; Boyce, Brad L.; Hattar, Khalid; Kotula, Paul G.; Hall, Aaron C.

    2016-01-01

    Aerosol deposition (AD) is a solid-state deposition technology that has been developed to fabricate ceramic coatings nominally at room temperature. Sub-micron ceramic particles accelerated by pressurized gas impact, deform, and consolidate on substrates under vacuum. Ceramic particle consolidation in AD coatings is highly dependent on particle deformation and bonding; these behaviors are not well understood. In this work, atomistic simulations and in situ micro-compressions in the scanning electron microscope, and the transmission electron microscope (TEM) were utilized to investigate fundamental mechanisms responsible for plastic deformation/fracture of particles under applied compression. Results showed that highly defective micron-sized alumina particles, initially containing numerous dislocations or a grain boundary, exhibited no observable shape change before fracture/fragmentation. Simulations and experimental results indicated that particles containing a grain boundary only accommodate low strain energy per unit volume before crack nucleation and propagation. In contrast, nearly defect-free, sub-micron, single crystal alumina particles exhibited plastic deformation and fracture without fragmentation. Dislocation nucleation/motion, significant plastic deformation, and shape change were observed. Simulation and TEM in situ micro-compression results indicated that nearly defect-free particles accommodate high strain energy per unit volume associated with dislocation plasticity before fracture. The identified deformation mechanisms provide insight into feedstock design for AD.

  18. Room temperature deformation mechanisms of alumina particles observed from in situ micro-compression and atomistic simulations.

    SciTech Connect

    Sarobol, Pylin; Chandross, Michael E.; Carroll, Jay D.; Mook, William M.; Bufford, Daniel Charles; Boyce, Brad L.; Hattar, Khalid Mikhiel; Kotula, Paul G.; Hall, Aaron Christopher

    2015-09-22

    Aerosol deposition (AD) is a solid-state deposition technology that has been developed to fabricate ceramic coatings nominally at room temperature. Sub-micron ceramic particles accelerated by pressurized gas impact, deform, and consolidate on substrates under vacuum. Ceramic particle consolidation in AD coatings is highly dependent on particle deformation and bonding; these behaviors are not well understood. In this work, atomistic simulations and in situ micro-compressions in the scanning electron microscope, and the transmission electron microscope (TEM) were utilized to investigate fundamental mechanisms responsible for plastic deformation/fracture of particles under applied compression. Results showed that highly defective micron-sized alumina particles, initially containing numerous dislocations or a grain boundary, exhibited no observable shape change before fracture/fragmentation. Simulations and experimental results indicated that particles containing a grain boundary only accommodate low strain energy per unit volume before crack nucleation and propagation. In contrast, nearly defect-free, sub-micron, single crystal alumina particles exhibited plastic deformation and fracture without fragmentation. Dislocation nucleation/motion, significant plastic deformation, and shape change were observed. Simulation and TEM in situ micro-compression results indicated that nearly defect-free particles accommodate high strain energy per unit volume associated with dislocation plasticity before fracture. As a result, the identified deformation mechanisms provide insight into feedstock design for AD.

  19. Room temperature deformation mechanisms of alumina particles observed from in situ micro-compression and atomistic simulations.

    DOE PAGES

    Sarobol, Pylin; Chandross, Michael E.; Carroll, Jay D.; Mook, William M.; Bufford, Daniel Charles; Boyce, Brad L.; Hattar, Khalid Mikhiel; Kotula, Paul G.; Hall, Aaron Christopher

    2015-09-22

    Aerosol deposition (AD) is a solid-state deposition technology that has been developed to fabricate ceramic coatings nominally at room temperature. Sub-micron ceramic particles accelerated by pressurized gas impact, deform, and consolidate on substrates under vacuum. Ceramic particle consolidation in AD coatings is highly dependent on particle deformation and bonding; these behaviors are not well understood. In this work, atomistic simulations and in situ micro-compressions in the scanning electron microscope, and the transmission electron microscope (TEM) were utilized to investigate fundamental mechanisms responsible for plastic deformation/fracture of particles under applied compression. Results showed that highly defective micron-sized alumina particles, initially containingmore » numerous dislocations or a grain boundary, exhibited no observable shape change before fracture/fragmentation. Simulations and experimental results indicated that particles containing a grain boundary only accommodate low strain energy per unit volume before crack nucleation and propagation. In contrast, nearly defect-free, sub-micron, single crystal alumina particles exhibited plastic deformation and fracture without fragmentation. Dislocation nucleation/motion, significant plastic deformation, and shape change were observed. Simulation and TEM in situ micro-compression results indicated that nearly defect-free particles accommodate high strain energy per unit volume associated with dislocation plasticity before fracture. As a result, the identified deformation mechanisms provide insight into feedstock design for AD.« less

  20. Oceanotron server for marine in-situ observations : a thematic data model implementation as a basis for the extensibility

    NASA Astrophysics Data System (ADS)

    Loubrieu, T.; Donnart, J. C.; Bregent, S.; Blower, J.; Griffith, G.

    2012-04-01

    Oceanotron (https://forge.ifremer.fr/plugins/mediawiki/wiki/oceanotron/index.php/Accueil) is an open-source data server dedicated to marine in-situ observation dissemination. For its extensibility it relies of an ocean business data model. IFREMER hosts the CORIOLIS marine in-situ data centre (http://www.coriolis.eu.org) and, as French NODC (National Oceanographic Data Centre, http://www.ifremer.fr/sismer/index_UK.htm), some other in-situ observation databases. As such IFREMER participates to numerous ocean data management projects. IFREMER wished to capitalize its thematic data management expertise in a dedicated data dissemination server called Oceanotron. The development of the server coordinated by IFREMER has started in 2010. Knowing the diversity of data repository formats (RDBMS, netCDF, ODV, MEDATLAS, ...) and the temperamental nature of the standard interoperability interface profiles (OGC/WMS, OGC/WFS, OGC/SOS, OpenDAP, …), the architecture of the software relies on an ocean business data model dedicated to marine in-situ observation features. The ocean business data model relies on the CSML conceptual modelling (http://csml.badc.rl.ac.uk/) and UNIDATA Common Data Model (http://www.unidata.ucar.edu/software/netcdf-java/CDM/) works and focuses on the most common marine observation features which are : vertical profiles, point series, trajectories and point. The ocean business data model has been implemented in java and can be used as an API. The oceanotron server orchestrates different types of modules handling the ocean business data model objects : - StorageUnits : which read specific data repository formats (netCDF/OceanSites, netCDF/ARGO, ...). - TransformationUnits : which apply useful ocean business related transformation to the features (for example conversion of vertical coordinates from pressure in dB to meters under sea surface). - FrontDesks : which get external requests and send results for interoperable protocols (OpenDAP, WMS, ...). These

  1. Ice Freezing In Storfjorden From Four Winters of Satellite and In Situ Observations

    NASA Astrophysics Data System (ADS)

    Skogseth, R.; Haugan, P. M.

    ERS-2-SAR images and in situ meteorological and hydrographic data have been col- lected during the freezing periods 1999/2000 and 2000/2001, extending the earlier study periods 1997/1998 and 1998/1999 [(Haarpaintner et al., 2001), (Haarpaintner et al., 2000)]. The study area Storfjorden is situated between the islands Spitsbergen, Barentöya and Edgeöya in the Svalbard Archipelago and is defined by an 115m deep sill at 76 45' N in the south and by a shallow bank Storfjordbanken in the south- east. Heleysundet and Freemansundet, two sounds in the north and northeast, connect Storfjorden with northwestern Barents Sea, and strong tidal currents are present in these sounds. A latent coastal polynya situated inside Storfjorden on the leeside off Edgeöya makes Storfjorden an "ice factory" due to the large heat flux in the polynya region. Brine-enriched Shelf Water (BSW), which is formed inside Storfjorden due to brine release from ice freezing, will have characteristics dependent on source wa- ter, ice production and position of the polynya inside Storfjorden. Onset of freezing was found from SAR, AVHRR and SSMI images available for Storfjorden. Classi- fication of fast ice, pack ice and polynya (open water and thin/new ice) was done from available SAR images in the four freezing periods. An existing one-dimensional polynya width model was used to calculate ice production of fast ice, pack ice, thin ice and frazil ice. Results from the SAR image classification and the polynya width model were compared to test and modify the model using the four-year time series. Also, sensitivity tests of the polynya width model were performed. Data from exten- sive hydrographic surveys in Storfjorden (Skogseth, Haugan and Nøst: Water mass transformations in Storfjorden, submitted EGS 2002) gives initial conditions before onset of freezing and conditions during and after freezing for each freezing period. Summer and autumn data give the resulting BSW characteristics after each

  2. On the interplanetary evolution of CME-driven shocks: a comparison between remote sensing observations and in-situ data

    NASA Astrophysics Data System (ADS)

    Volpes, Laura; Bothmer, Volker

    2015-08-01

    Fast coronal mass ejections (CMEs) are a prime driver of major space weather effects and strong geomagnetic storms. When the CME propagation speed is higher than the Alfvén speed a shock forms in front of the CME leading edge. CME-driven shocks are observed in in-situ data and, with the advent of increasingly sensitive imaging instruments, also in remote sensing observations in the form of bright fronts ahead of the CMEs.In this work we present the study of 4 Earth-directed CMEs which drove shocks detected in STEREO COR 2 and HI observations. For each event we identify the source region and the signatures of CME eruption such as waves, EUV dimmings, flare and prominence eruptions. The shock and CME interplanetary evolution is determined from COR2 and HI observations via an application of triangulation techniques. Furthermore, propagation speed and arrival times are inferred. The CME geometry is modelled in COR2 via the graduated cylindrical shell (GCS) model and the assumption on self-similar expansion is tested by expanding the flux rope to the HI1 field of view. A combination of these results with models for the shock location allows to infer the time evolution of the compression ratio ρd/ρu across the shock and of the upstream Mach number M at locations where no direct plasma measurements are available. These values, as well as the arrival time and speed, are compared to ACE in-situ measurements to validate the results. For the 03 April 2010 event, e.g., the values of the Mach number and the compression ratio extrapolated to the position of ACE are respectively 2.1 < ρd/ρu < 2.4 and 2.3 < M < 2.5, in good agreement with the in-situ values found in literature, ρd/ρu = 2.84 and M = 2.2. This study is carried out in conjunction to simulations of CME initiation. Combined results from observations and simulations allow to connect the interplanetary and near-Earth properties of CMEs to those of their source regions, and to the mechanisms of CME onset.

  3. Evolution and Consequences of Interacting CMEs of 9 - 10 November 2012 Using STEREO/SECCHI and In Situ Observations

    NASA Astrophysics Data System (ADS)

    Mishra, Wageesh; Srivastava, Nandita; Chakrabarty, D.

    2015-02-01

    Understanding the kinematic evolution of coronal mass ejections (CMEs) in the heliosphere is important to estimate their arrival time at Earth. The kinematics of CMEs can change when they interact or collide with each other as they propagate in the heliosphere. In this article, we analyze the collision and post-interaction characteristics of two Earth-directed CMEs that were launched successively on 9 and 10 November 2012. To do this, we used white-light imaging observations from STEREO/SECCHI and in situ observations taken from the Wind spacecraft. We tracked two density-enhancement features associated with the leading and trailing edge of the 9 November CME and one density enhanced feature associated with the leading edges of the 10 November CME by constructing J-maps. We found that the leading edge of the 10 November CME interacted with the trailing edge of the 9 November CME. We also estimated the kinematics of these features of the CMEs and found a significant change in their dynamics after interaction. In in situ observations, we identified distinct structures associated with interacting CMEs and also observed heating and compression as signatures of their interaction. Our analysis shows an improvement in the arrival-time prediction of CMEs when their post-collision dynamics are used instead of the pre-collision dynamics. By estimating the true masses and speeds of these colliding CMEs, we investigated the nature of the observed collision, which is found to be almost perfectly inelastic. The investigation also places in perspective the geomagnetic consequences of the two CMEs and their interaction in terms of occurrence of geomagnetic storms and triggering of magnetospheric substorms.

  4. 5- to 13-micron airborne observations of Comet Wilson 1986l

    SciTech Connect

    Lynch, D.K.; Russell, R.W.; Campins, H.; Witteborn, F.C.; Bregman, J.D. Planetary Science Institute, Tucson, AZ Florida Univ., Gainesville NASA, Ames Research Center, Moffett Field, CA )

    1989-12-01

    Comet Wilson was observed from the Kuiper Airborne Observatory approximately 23.6 and 25.7 Apr. 1987, UT (approx. 3 to 5 days after perihelion) using the NASA-Ames Faint Object Grating Spectrometer. Spectrophotometric data were observed with a 21 inch aperture between 5 and 13 micrometer and with a spectral resolution of 50 to 100. Spectra of the inner coma and nucleus reveal a fairly smooth continuum with little evidence of silicate emission. The 5 to 8 micrometer color temperature of the comet was 300 + or - 15 K, approx. 15 percent higher than the equilibrium blackbody temperature. All three spectra of the nucleus show a new emission feature at approx. 12.25 micrometer approx. two channels (.22 micrometer) wide. Visual and photographic observations made during the time of these observations showed a broad faint, possible two component tail. No outburst activity was observed. 21 refs.

  5. Airborne Observations of Urban-Derived Water Vapor and Potential Impacts on Chemistry and Clouds

    NASA Astrophysics Data System (ADS)

    Salmon, O. E.; Shepson, P. B.; Grundman, R. M., II; Stirm, B. H.; Ren, X.; Dickerson, R. R.; Fuentes, J. D.

    2015-12-01

    Atmospheric conditions typical of wintertime, such as lower boundary layer heights and reduced turbulent mixing, provide a unique environment for anthropogenic pollutants to accumulate and react. Wintertime enhancements in water vapor (H2O) have been observed in urban areas, and are thought to result from fossil fuel combustion and urban heat island-induced evaporation. The contribution of urban-derived water vapor to the atmosphere has the potential to locally influence atmospheric chemistry and weather for the urban area and surrounding region due to interactions between H2O and other chemical species, aerosols, and clouds. Airborne observations of urban-derived H2O, carbon dioxide (CO2), methane, nitrogen dioxide (NO2), ozone, and aerosols were conducted from Purdue University's Airborne Laboratory for Atmospheric Research (ALAR) and the University of Maryland's (UMD) Twin Cessna research aircraft during the winter of 2015. Measurements were conducted as part of the collaborative airborne campaign, Wintertime INvestigation of Transport, Emissions, and Reactivity (WINTER), which investigated seasonal trends in anthropogenic emissions and reactivity in the Northeastern United States. ALAR and the UMD aircraft participated in mass balance experiments around Washington D.C.-Baltimore to determine total city emission rates of H2O and other greenhouse gases. Average enhancements in H2O mixing ratio of 0.048%, and up to 0.13%, were observed downwind of the urban centers on ten research flights. In some cases, downwind H2O concentrations clearly track CO2 and NO2 enhancements, suggesting a strong combustion signal. Analysis of Purdue and UMD data collected during the WINTER campaign shows an average urban-derived H2O contribution of 5.3%, and as much as 13%, to the local boundary layer from ten research flights flown in February and March of 2015. In this paper, we discuss the potential chemical and physical implications of these results.

  6. Toward the Direct Measurement of Coronal Magnetic Fields: An Airborne Infrared Spectrometer for Eclipse Observations

    NASA Astrophysics Data System (ADS)

    Samra, J.; DeLuca, E. E.; Golub, L.; Cheimets, P.

    2014-12-01

    The solar magnetic field enables the heating of the corona and provides its underlying structure. Energy stored in coronal magnetic fields is released in flares and coronal mass ejections (CME) and provides the ultimate source of energy for space weather. Therefore, direct measurements of the coronal magnetic field have significant potential to enhance understanding of coronal dynamics and improve solar forecasting models. Of particular interest are observations of coronal field lines in the transitional region between closed and open flux systems, providing important information on the origin of the slow solar wind. While current instruments routinely observe only the photospheric and chromospheric magnetic fields, a proposed airborne spectrometer will take a step toward the direct observation of coronal fields by measuring plasma emission in the infrared at high spatial and spectral resolution. The targeted lines are four forbidden magnetic dipole transitions between 2 and 4 μm. The airborne system will consist of a telescope, grating spectrometer, and pointing/stabilization system to be flown on the NSF/NCAR High-performance Instrumented Airborne Platform for Environmental Research (HIAPER) during the August 2017 total solar eclipse. The project incorporates several optical engineering challenges, centered around maintaining adequate spectral and spatial resolution in a compact and inexpensive package and on a moving platform. Design studies are currently underway to examine the tradeoffs between various optical geometries and control strategies for the pointing/stabilization system. The results will be presented and interpreted in terms of the consequences for the scientific questions. In addition, results from a laboratory prototype and simulations of the final system will be presented.

  7. Observation of localized heating phenomena during microwave heating of mixed powders using in situ x-ray diffraction technique

    NASA Astrophysics Data System (ADS)

    Sabelström, N.; Hayashi, M.; Watanabe, T.; Nagata, K.

    2014-10-01

    In materials processing research using microwave heating, there have been several observations of various phenomena occurring known as microwave effects. One significant example of such a phenomenon is increased reaction kinetics. It is believed that there is a possibility that this might be caused by localized heating, were some reactants would attain a higher than apparent temperature. To examine whether such thermal gradients are indeed possible, mixed powders of two microwave non-absorbers, alumina and magnesia, were mixed with graphite, a known absorber, and heated in a microwave furnace. During microwave irradiation, the local temperatures of the respective sample constituents were measured using an in situ x-ray diffraction technique. In the case of the alumina and graphite sample, a temperature difference of around 100 °C could be observed.

  8. In situ Transmission Electron Microscopy observation of Ag nanocrystal evolution by surfactant free electron-driven synthesis

    PubMed Central

    Longo, Elson; Avansi, Waldir; Bettini, Jefferson; Andrés, Juan; Gracia, Lourdes

    2016-01-01

    The study of the interaction of electron irradiation with matter and the response of the material to the passage of electrons is a very challenging problem. However, the growth mechanism observed during nanostructural evolution appears to be a broad and promising scientific field in nanotechnology. We report the in situ TEM study of nanostructural evolution of electron-driven silver (Ag) nanocrystals through an additive-free synthetic procedure. Observations revealed the direct effect of the electron beam on the morphological evolution of Ag nanocrystals through different mechanisms, such as mass transport, site-selective coalescence, and an appropriate structural configuration after coalescence leading to a more stable configuration. A fundamental understanding of the growth and formation mechanisms of Ag nanocrystals, which interact with the electron beam, is essential to improve the nanocrystal shape-control mechanisms as well as the future design and study of nanomaterials. PMID:26979671

  9. Sol-to-Gel Transition in Fast Evaporating Systems Observed by in Situ Time-Resolved Infrared Spectroscopy.

    PubMed

    Innocenzi, Plinio; Malfatti, Luca; Carboni, Davide; Takahashi, Masahide

    2015-06-22

    The in situ observation of a sol-to-gel transition in fast evaporating systems is a challenging task and the lack of a suitable experimental design, which includes the chemistry and the analytical method, has limited the observations. We synthesise an acidic sol, employing only tetraethylorthosilicate, SiCl4 as catalyst and deuterated water; the absence of water added to the sol allows us to follow the absorption from the external environment and the evaporation of deuterated water. The time-resolved data, obtained by attenuated total reflection infrared spectroscopy on an evaporating droplet, enables us to identify four different stages during evaporation. They are linked to specific hydrolysis and condensation rates that affect the uptake of water from external environment. The second stage is characterized by a decrease in hydroxyl content, a fast rise of condensation rate and an almost stationary absorption of water. This stage has been associated with the sol-to-gel transition.

  10. In-situ visual observation for the formation and dissociation of methane hydrates in porous media by magnetic resonance imaging.

    PubMed

    Zhao, Jiafei; Lv, Qin; Li, Yanghui; Yang, Mingjun; Liu, Weiguo; Yao, Lei; Wang, Shenglong; Zhang, Yi; Song, Yongchen

    2015-05-01

    In this work, magnetic resonance imaging (MRI) was employed to observe the in-situ formation and dissociation of methane hydrates in porous media. Methane hydrate was formed in a high-pressure cell with controlled temperature, and then the hydrate was dissociated by thermal injection. The process was photographed by the MRI, and the pressure was recorded. The images confirmed that the direct visual observation was achieved; these were then employed to provide detailed information of the nucleation, growth, and decomposition of the hydrate. Moreover, the saturation of methane hydrate during the dissociation was obtained from the MRI intensity data. Our results showed that the hydrate saturation initially decreased rapidly, and then slowed down; this finding is in line with predictions based only on pressure. The study clearly showed that MRI is a useful technique to investigate the process of methane hydrate formation and dissociation in porous media.

  11. Observation of localized heating phenomena during microwave heating of mixed powders using in situ x-ray diffraction technique

    SciTech Connect

    Sabelström, N. Hayashi, M.; Watanabe, T.; Nagata, K.

    2014-10-28

    In materials processing research using microwave heating, there have been several observations of various phenomena occurring known as microwave effects. One significant example of such a phenomenon is increased reaction kinetics. It is believed that there is a possibility that this might be caused by localized heating, were some reactants would attain a higher than apparent temperature. To examine whether such thermal gradients are indeed possible, mixed powders of two microwave non-absorbers, alumina and magnesia, were mixed with graphite, a known absorber, and heated in a microwave furnace. During microwave irradiation, the local temperatures of the respective sample constituents were measured using an in situ x-ray diffraction technique. In the case of the alumina and graphite sample, a temperature difference of around 100 °C could be observed.

  12. In-situ Observation of Surface Graphitization of Gallium Droplet and Concentration of Carbon in Liquid Gallium

    NASA Astrophysics Data System (ADS)

    Ueki, Ryuichi; Nishijima, Takuya; Hikata, Takeshi; Ookubo, Soichiro; Utsunomiya, Risa; Matsuba, Teruaki; Fujita, Jun-ichi

    2012-06-01

    Although carbon has been recognized to be insoluble in gallium, we found that the outermost surface of gallium has unexpectedly high carbon solubility, particularly the limited region of about a few nanometers in depth. Our in-situ transmission electron microscope observations revealed that a graphene layer was precipitated at the surface of a gallium droplet simultaneously with gallium evaporation, and some of the droplets created an internal graphitic layer. On the basis of these experimental data, we evaluated a substantial carbon solubility that seemed to exceed about 50 at. %, but was realized in a very thin surface region of about 4 nm in depth. We believe that this high carbon solubility at the gallium surface is the key mechanism for the catalytic ability of gallium that was observed at the interface between liquid gallium and solid amorphous carbon.

  13. Observing Metal-Catalyzed Chemical Reactions in Situ Using Surface-Enhanced Raman Spectroscopy on Pd–Au Nanoshells

    PubMed Central

    Heck, Kimberly N.; Janesko, Benjamin G.; Scuseria, Gustavo E.

    2016-01-01

    Insight into the nature of transient reaction intermediates and mechanistic pathways involved in heterogeneously catalyzed chemical reactions is obtainable from a number of surface spectroscopic techniques. Carrying out these investigations under actual reaction conditions is preferred but remains challenging, especially for catalytic reactions that occur in water. Here, we report the direct spectroscopic study of the catalytic hydrodechlorination of 1,1-dichloroethene in H2O using surface-enhanced Raman spectroscopy (SERS). With Pd islands grown on Au nanoshell films, this reaction can be followed in situ using SERS, exploiting the high enhancements and large active area of Au nanoshell SERS substrates, the transparency of Raman spectroscopy to aqueous solvents, and the catalytic activity enhancement of Pd by the underlying Au metal. The formation and subsequent transformation of several adsorbate species was observed. These results provide the first direct evidence of the room-temperature catalytic hydrodechlorination of a chlorinated solvent, a potentially important pathway for groundwater cleanup, as a sequence of dechlorination and hydrogenation steps. More broadly, the results highlight the exciting prospects of studying catalytic processes in water in situ, like those involved in biomass conversion and proton-exchange membrane fuel cells. PMID:19554693

  14. Gravity anomalies and lithospheric flexure around the Longmen Shan deduced from combinations of in situ observations and EGM2008 data

    NASA Astrophysics Data System (ADS)

    She, Yawen; Fu, Guangyu; Wang, Zhuohua; Liu, Tai; Xu, Changyi; Jin, Honglin

    2016-10-01

    The current work describes the combined data of three field campaigns, spanning 2009-2013. Their joint gravity and GPS observations thoroughly cover the sites of lithospheric flexure between the Sichuan Basin and the Eastern Tibetan Plateau. The study area's free-air gravity anomalies (FGAs) are updated by using a remove-and-restore algorithm which merges EGM2008 data with in situ observations. These new FGAs show pairs of positive and negative anomalies along the eastern edges of the Tibetan Plateau. The FGAs are used to calculate effective elastic thickness ( T e) and load ratios ( F) of the lithosphere. Admittance analysis indicates the T e of Longmen Shan (LMS) to be 6 km, and profile analysis indicates that the T e of the Sichuan Basin excesses 30 km. The load ratio ( F 1 = 1) confirms that the lithospheric flexure of the LMS area can be attributed solely to the surface load of the crust. [Figure not available: see fulltext. Caption: The current work describes the combined data of three field campaigns, spanning 2009-2013. Their joint gravity and GPS observations thoroughly cover the sites of lithospheric flexure between the Sichuan Basin and the Eastern Tibetan Plateau. The study area's free-air gravity anomalies (FGAs) are updated by using a remove-and-restore algorithm which merges EGM2008 data with in situ observations. With the new FGAs data, the lithospheric strength of the study area is studied by the authors, and they also give a combined model to illustrate the uplift mechanism of this area.

  15. Release History of Solar Energetic Electrons Inferred from In-situ Observations in the Inner Heliosphere

    NASA Astrophysics Data System (ADS)

    Agueda, Neus; Lario, David

    2016-07-01

    We present a detailed study of four 300-800 keV electron events observed on 1980 May 28-29 by Helios-1, when the spacecraft was located at 0.31 AU from the Sun. We use two different techniques to extract the release time history of the electrons at the Sun: 1) an inversion method that makes use of particle transport simulation results, and 2) a data-driven method based on the assumption that the interplanetary propagation between the Sun and the spacecraft is essentially scatter free. Both methods make use of the particle angular distributions measured relative to the local direction of the magnetic field (i.e., pitch-angle distributions). The general characteristics of the release time profile obtained for the four events is remarkably similar, specially when the inferred value of the electron mean free path is large. We use these results to compute the expected intensities at 1 AU. For an observer at 1 AU magnetically connected with Helios-1, our simulations predict the observation of four separate events, which does not agree with the interpretation of the IMP-8 observations suggesting that the discrete events observed at 0.31 AU merged into a single event at 1 AU. We discuss the processes that could contribute to the observation of one single time-extended event at 1 AU and how these techniques could be used to analyze upcoming measurements by Solar Orbiter and Solar Probe Plus close to the Sun.

  16. A Global Synthesis Inversion Analysis of Recent Variability in Natural CO2 Fluxes Using Gosat and in Situ Observations

    NASA Astrophysics Data System (ADS)

    Wang, J. S.; Kawa, S. R.; Collatz, G. J.

    2014-12-01

    About one-half of the CO2 emissions from fossil fuel combustion and deforestation accumulates in the atmosphere, where it contributes to global warming. The rest is taken up by vegetation and the ocean. The precise contribution of the two, and the location and year-to-year variability of the CO2 sinks are, however, not well understood. We use a batch Bayesian inversion approach to deduce the global spatiotemporal distributions of CO2 fluxes during 2009-2010. For prior constraints, we utilize fluxes from the CASA-GFED model of the terrestrial biosphere and biomass burning driven by satellite observations and interannually varying meteorology. We also use measurement-based ocean flux estimates, and fixed fossil CO2 emissions. Here, we present results from our inversions that incorporate column CO2 measurements from the GOSAT satellite (ACOS retrieval, filtered and bias-corrected) and in situ observations (individual flask and afternoon-average continuous observations) to estimate fluxes in 108 regions over 8-day intervals. Relationships between fluxes and atmospheric concentrations are derived using the PCTM atmospheric transport model run at 2° x 2.5° (latitude/longitude) resolution driven by meteorology from the MERRA reanalysis. We evaluate the posterior CO2 concentrations using independent aircraft and other data sets. The optimized fluxes generally resemble those from other inversion systems using different techniques, for example indicating a net terrestrial biospheric CO2 sink, and a shift in the sink from tropics to northern high latitudes when going from an in-situ-only inversion to a GOSAT inversion. We show that in this inversion framework, GOSAT provides better flux estimates in most regions with its greater spatial coverage, but we also discuss impacts of possible remaining biases in the data.

  17. Distribution and habitat association of benthic fish on the Condor seamount (NE Atlantic, Azores) from in situ observations

    NASA Astrophysics Data System (ADS)

    Porteiro, Filipe M.; Gomes-Pereira, José N.; Pham, Christopher K.; Tempera, Fernando; Santos, Ricardo S.

    2013-12-01

    Distribution of fish assemblages and habitat associations of demersal fishes on the Condor seamount were investigated by analyzing in situ video imagery acquired by the Remotely-Operated Vehicles ROV SP300 and Luso 6000. A total of 51 fish taxa from 32 families were inventoried. Zooplanktivores (10 species) were the most abundant group followed by carnivores (23 species) and benthivores (18 species). Non-metric multidimensional scaling (MDS) analyses were performed on dive segments to visualize the spatial relationships between species and habitat type, substrate type or depth, with depth being the most significant parameter influencing fish distribution. Four major fish groups were identified from their vertical distribution alone: summit species (generally to <300 m depth); broad ranging species (ca. from 200 to 800 m); intermediate ranging slope species (ca. from 400 m to 800-850 m); and deeper species (800-850-1100 m). The fish fauna observed at the summit is more abundant (15.2 fish/100 m2) and habitat-specialized than the fish observed along the seamount slope. Down the seamount slope, the summit fish assemblage is gradually replaced as depth increases, with an overall reduction in abundance. On the summit, three species (Callanthias ruber, Anthias anthias and Lappanella fasciata) had higher affinity to coral habitats compared to non-coral habitats. A coherent specialized fish assemblage associated to coral habitats could not be identified, because most species were observed also in non-coral areas. On the seamount's slope (300-1100 m), no relationship between fish and coral habitats could be identified, although these might occur at larger scales. This study shows that in situ video imagery complements traditional fishing surveys, by providing information on unknown or rarely seen species, being fundamental for the development of more comprehensive ecosystem-based management towards a sustainable use of the marine environment.

  18. Temperature monitoring along the Rhine River based on airborne thermal infrared remote sensing: qualitative results compared to satellite data and validation with in situ measurements

    NASA Astrophysics Data System (ADS)

    Fricke, Katharina; Baschek, Björn

    2014-10-01

    Water temperature is an important parameter of water quality and influences other physical and chemical parameters. It also directly influences the survival and growth of animal and plant species in river ecosystems. In situ measurements do not allow for a total spatial coverage of water bodies and rivers that is necessary for monitoring and research at the Federal Institute of Hydrology (BfG), Germany. Hence, the ability of different remote sensing products to identify and investigate water inflows and water temperatures in Federal waterways is evaluated within the research project 'Remote sensing of water surface temperature'. The research area for a case study is the Upper and Middle Rhine River from the barrage in Iffezheim to Koblenz. Satellite products (e. g. Landsat and ASTER imagery) can only be used for rivers at least twice as wide as the spatial resolution of the satellite images. They can help to identify different water bodies only at tributaries with larger inflow volume (Main and Mosel) or larger temperature differences between the inflow (e. g. from power plants working with high capacity) and the river water. To identify and investigate also smaller water inflows and temperature differences, thermal data with better ground and thermal resolution is required. An aerial survey of the research area was conducted in late October 2013. Data of the surface was acquired with two camera systems, a digital camera with R, G, B, and Near-IR channels, and a thermal imaging camera measuring the brightness temperature in the 8-12 m wavelength region (TIR). The resolution of the TIR camera allowed for a ground resolution of 4 m, covering the whole width of the main stream and larger branches. The RGB and NIR data allowed to eliminate land surface temperatures from the analysis and to identify clouds and shadows present during the data acquisition. By degrading the spatial resolution and adding sensor noise, artificial Landsat ETM+ and TIRS datasets were created

  19. In situ observations of reconnection Hall magnetic fields at Mars: Evidence for ion diffusion region encounters

    NASA Astrophysics Data System (ADS)

    Halekas, J. S.; Eastwood, J. P.; Brain, D. A.; Phan, T. D.; Øieroset, M.; Lin, R. P.

    2009-11-01

    We present Mars Global Surveyor measurements of bipolar out-of-plane magnetic fields at current sheets in Mars' magnetosphere. These signatures match predictions from simulations and terrestrial observations of collisionless magnetic reconnection, and could similarly indicate differential ion and electron motion and the resulting Hall current systems near magnetic X lines. Thus, these observations may represent passages through or very near reconnection diffusion regions at Mars. Out of 28 events found at 400 km altitude with well-defined current sheet orientations, 26 have magnetic fields consistent with the expected polarities of Hall fields near diffusion regions. For these events, we find an average ratio of Hall field to main field of 0.51 ± 0.13, and an average ratio of normal to main field (reconnection rate) of 0.16 ± 0.09, consistent with terrestrial observations of reconnection. These events do not consistently correlate with the location of crustal fields or with IMF reversals, indicating that magnetic field draping alone (perhaps enhanced by high solar wind dynamic pressure) may generate current sheets capable of reconnection. For some events, we observe field-aligned electrons that may carry parallel currents that close the Hall current loop. Electron distributions around current sheets often indicate magnetic connection to the collisional exosphere. For crossings sunward of the X line, we usually observe an electron flux minimum at the current sheet, consistent with the resulting closed magnetic structure. For crossings antisunward of the X line, we do not observe flux minima, consistent with field lines open downstream. Collisionless reconnection, if common at Mars, could represent a significant atmospheric loss process.

  20. Review: advances in in situ and satellite phenological observations in Japan.

    PubMed

    Nagai, Shin; Nasahara, Kenlo Nishida; Inoue, Tomoharu; Saitoh, Taku M; Suzuki, Rikie

    2016-04-01

    To accurately evaluate the responses of spatial and temporal variation of ecosystem functioning (evapotranspiration and photosynthesis) and services (regulating and cultural services) to the rapid changes caused by global warming, we depend on long-term, continuous, near-surface, and satellite remote sensing of phenology over wide areas. Here, we review such phenological studies in Japan and discuss our current knowledge, problems, and future developments. In contrast with North America and Europe, Japan has been able to evaluate plant phenology along vertical and horizontal gradients within a narrow area because of the country's high topographic relief. Phenological observation networks that support scientific studies and outreach activities have used near-surface tools such as digital cameras and spectral radiometers. Differences in phenology among ecosystems and tree species have been detected by analyzing the seasonal variation of red, green, and blue digital numbers (RGB values) extracted from phenological images, as well as spectral reflectance and vegetation indices. The relationships between seasonal variations in RGB-derived indices or spectral characteristics and the ecological and CO2 flux measurement data have been well validated. In contrast, insufficient satellite remote-sensing observations have been conducted because of the coarse spatial resolution of previous datasets, which could not detect the heterogeneous plant phenology that results from Japan's complex topography and vegetation. To improve Japanese phenological observations, multidisciplinary analysis and evaluation will be needed to link traditional phenological observations with "index trees," near-surface and satellite remote-sensing observations, "citizen science" (observations by citizens), and results published on the Internet.

  1. Review: advances in in situ and satellite phenological observations in Japan

    NASA Astrophysics Data System (ADS)

    Nagai, Shin; Nasahara, Kenlo Nishida; Inoue, Tomoharu; Saitoh, Taku M.; Suzuki, Rikie

    2016-04-01

    To accurately evaluate the responses of spatial and temporal variation of ecosystem functioning (evapotranspiration and photosynthesis) and services (regulating and cultural services) to the rapid changes caused by global warming, we depend on long-term, continuous, near-surface, and satellite remote sensing of phenology over wide areas. Here, we review such phenological studies in Japan and discuss our current knowledge, problems, and future developments. In contrast with North America and Europe, Japan has been able to evaluate plant phenology along vertical and horizontal gradients within a narrow area because of the country's high topographic relief. Phenological observation networks that support scientific studies and outreach activities have used near-surface tools such as digital cameras and spectral radiometers. Differences in phenology among ecosystems and tree species have been detected by analyzing the seasonal variation of red, green, and blue digital numbers (RGB values) extracted from phenological images, as well as spectral reflectance and vegetation indices. The relationships between seasonal variations in RGB-derived indices or spectral characteristics and the ecological and CO2 flux measurement data have been well validated. In contrast, insufficient satellite remote-sensing observations have been conducted because of the coarse spatial resolution of previous datasets, which could not detect the heterogeneous plant phenology that results from Japan's complex topography and vegetation. To improve Japanese phenological observations, multidisciplinary analysis and evaluation will be needed to link traditional phenological observations with "index trees," near-surface and satellite remote-sensing observations, "citizen science" (observations by citizens), and results published on the Internet.

  2. Review: advances in in situ and satellite phenological observations in Japan.

    PubMed

    Nagai, Shin; Nasahara, Kenlo Nishida; Inoue, Tomoharu; Saitoh, Taku M; Suzuki, Rikie

    2016-04-01

    To accurately evaluate the responses of spatial and temporal variation of ecosystem functioning (evapotranspiration and photosynthesis) and services (regulating and cultural services) to the rapid changes caused by global warming, we depend on long-term, continuous, near-surface, and satellite remote sensing of phenology over wide areas. Here, we review such phenological studies in Japan and discuss our current knowledge, problems, and future developments. In contrast with North America and Europe, Japan has been able to evaluate plant phenology along vertical and horizontal gradients within a narrow area because of the country's high topographic relief. Phenological observation networks that support scientific studies and outreach activities have used near-surface tools such as digital cameras and spectral radiometers. Differences in phenology among ecosystems and tree species have been detected by analyzing the seasonal variation of red, green, and blue digital numbers (RGB values) extracted from phenological images, as well as spectral reflectance and vegetation indices. The relationships between seasonal variations in RGB-derived indices or spectral characteristics and the ecological and CO2 flux measurement data have been well validated. In contrast, insufficient satellite remote-sensing observations have been conducted because of the coarse spatial resolution of previous datasets, which could not detect the heterogeneous plant phenology that results from Japan's complex topography and vegetation. To improve Japanese phenological observations, multidisciplinary analysis and evaluation will be needed to link traditional phenological observations with "index trees," near-surface and satellite remote-sensing observations, "citizen science" (observations by citizens), and results published on the Internet. PMID:26307639

  3. Utilizing Free and Open Source Software to access, view and compare in situ observations, EO products and model output data

    NASA Astrophysics Data System (ADS)

    Vines, Aleksander; Hamre, Torill; Lygre, Kjetil

    2014-05-01

    The GreenSeas project (Development of global plankton data base and model system for eco-climate early warning) aims to advance the knowledge and predictive capacities of how marine ecosystems will respond to global change. A main task has been to set up a data delivery and monitoring core service following the open and free data access policy implemented in the Global Monitoring for the Environment and Security (GMES) programme. The aim is to ensure open and free access to historical plankton data, new data (EO products and in situ measurements), model data (including estimates of simulation error) and biological, environmental and climatic indicators to a range of stakeholders, such as scientists, policy makers and environmental managers. To this end, we have developed a geo-spatial database of both historical and new in situ physical, biological and chemical parameters for the Southern Ocean, Atlantic, Nordic Seas and the Arctic, and organized related satellite-derived quantities and model forecasts in a joint geo-spatial repository. For easy access to these data, we have implemented a web-based GIS (Geographical Information Systems) where observed, derived and forcasted parameters can be searched, displayed, compared and exported. Model forecasts can also be uploaded dynamically to the system, to allow modelers to quickly compare their results with available in situ and satellite observations. We have implemented the web-based GIS(Geographical Information Systems) system based on free and open source technologies: Thredds Data Server, ncWMS, GeoServer, OpenLayers, PostGIS, Liferay, Apache Tomcat, PRTree, NetCDF-Java, json-simple, Geotoolkit, Highcharts, GeoExt, MapFish, FileSaver, jQuery, jstree and qUnit. We also wanted to used open standards to communicate between the different services and we use WMS, WFS, netCDF, GML, OPeNDAP, JSON, and SLD. The main advantage we got from using FOSS was that we did not have to invent the wheel all over again, but could use

  4. Liparid and macrourid fishes of the hadal zone: in situ observations of activity and feeding behaviour

    PubMed Central

    Jamieson, A.J.; Fujii, T.; Solan, M.; Matsumoto, A.K.; Bagley, P.M.; Priede, I.G.

    2008-01-01

    Using baited camera landers, the first images of living fishes were recorded in the hadal zone (6000–11 000 m) in the Pacific Ocean. The widespread abyssal macrourid Coryphaenoides yaquinae was observed at a new depth record of approximately 7000 m in the Japan Trench. Two endemic species of liparid were observed at similar depths: Pseudoliparis amblystomopsis in the Japan Trench and Notoliparis kermadecensis in the Kermadec Trench. From these observations, we have documented swimming and feeding behaviour of these species and derived the first estimates of hadal fish abundance. The liparids intercepted bait within 100–200 min but were observed to preferentially feed on scavenging amphipods. Notoliparis kermadecensis act as top predators in the hadal food web, exhibiting up to nine suction-feeding events per minute. Both species showed distinctive swimming gaits: P. amblystomopsis (mean length 22.5 cm) displayed a mean tail-beat frequency of 0.47 Hz and mean caudal : pectoral frequency ratio of 0.76, whereas N. kermadecensis (mean length 31.5 cm) displayed respective values of 1.04 and 2.08 Hz. Despite living at extreme depths, these endemic liparids exhibit similar activity levels compared with shallow-water liparids. PMID:19129104

  5. In situ observations of "cold trap" dehydration in the western tropical Pacific

    NASA Astrophysics Data System (ADS)

    Hasebe, F.; Fujiwara, M.; Nishi, N.; Shiotani, M.; Vömel, H.; Oltmans, S.; Takashima, H.; Saraspriya, S.; Komala, N.

    2006-07-01

    Water vapor sonde observations were conducted at Bandung, Indonesia (6.90 S, 107.60 E) and Tarawa, Kiribati (1.35 N, 172.91 E) in December 2003 to examine the efficiency of the "cold trap'' dehydration in the tropical tropopause layer (TTL). Trajectory analysis based on bundles of trajectories suggest that the modification of air parcels' identity due to irreversible mixing by the branching-out and merging-in of nearby trajectories is found to be an important factor, in addition to the routes air parcels are supposed to follow, for interpreting the water vapor concentrations observed by radiosondes in the TTL. Clear correspondence between the observed water vapor concentration and the estimated temperature history of air parcels is found showing that dry air parcels are exposed to low temperatures while humid air parcels do not experience cold conditions during advection, in support of the "cold trap'' hypothesis. It is suggested that the observed air parcel retained the water vapor by roughly twice as much as the minimum saturation mixing ratio after its passage through the "cold trap,'' although appreciable uncertainties remain.

  6. Liparid and macrourid fishes of the hadal zone: in situ observations of activity and feeding behaviour.

    PubMed

    Jamieson, A J; Fujii, T; Solan, M; Matsumoto, A K; Bagley, P M; Priede, I G

    2009-03-22

    Using baited camera landers, the first images of living fishes were recorded in the hadal zone (6000-11000 m) in the Pacific Ocean. The widespread abyssal macrourid Coryphaenoides yaquinae was observed at a new depth record of approximately 7000 m in the Japan Trench. Two endemic species of liparid were observed at similar depths: Pseudoliparis amblystomopsis in the Japan Trench and Notoliparis kermadecensis in the Kermadec Trench. From these observations, we have documented swimming and feeding behaviour of these species and derived the first estimates of hadal fish abundance. The liparids intercepted bait within 100-200 min but were observed to preferentially feed on scavenging amphipods. Notoliparis kermadecensis act as top predators in the hadal food web, exhibiting up to nine suction-feeding events per minute. Both species showed distinctive swimming gaits: P. amblystomopsis (mean length 22.5 cm) displayed a mean tail-beat frequency of 0.47 Hz and mean caudal:pectoral frequency ratio of 0.76, whereas N. kermadecensis (mean length 31.5 cm) displayed respective values of 1.04 and 2.08 Hz. Despite living at extreme depths, these endemic liparids exhibit similar activity levels compared with shallow-water liparids. PMID:19129104

  7. GPS and in situ Swarm observations of the equatorial plasma density irregularities in the topside ionosphere

    NASA Astrophysics Data System (ADS)

    Zakharenkova, Irina; Astafyeva, Elvira; Cherniak, Iurii

    2016-07-01

    Here we study the global distribution of the plasma density irregularities in the topside ionosphere by using the concurrent GPS and Langmuir probe measurements onboard the Swarm satellites. We analyze 18 months (from August 2014 till January 2016) of data from Swarm A and B satellites that flew at 460 and 510 km altitude, respectively. To identify the occurrence of the ionospheric irregularities, we have analyzed behavior of two indices ROTI and RODI based on the change rate of total electron content and electron density, respectively. The obtained results demonstrate a high degree of similarities in the occurrence pattern of the seasonal and longitudinal distribution of the topside ionospheric irregularities derived from both types of the satellite observations. Among the seasons with good data coverage, the maximal occurrence rates for the post-sunset equatorial irregularities reached 35-50 % for the September 2014 and March 2015 equinoxes and only 10-15 % for the June 2015 solstice. For the equinox seasons the intense plasma density irregularities were more frequently observed in the Atlantic sector, for the December solstice in the South American-Atlantic sector. The highest occurrence rates for the post-midnight irregularities were observed in African longitudinal sector during the September 2014 equinox and June 2015 solstice. The observed differences in SWA and SWB results could be explained by the longitude/LT separation between satellites, as SWB crossed the same post-sunset sector increasingly later than the SWA did.

  8. IN-SITU SEQUESTRATION OF ZINC: SPECTROSCOPIC OBSERVATIONS FROM A FIELD STUDY

    EPA Science Inventory

    Zinc concentrations in the soil and groundwater at the Indian Head Naval Warfare Center, located in Charles County Maryland, have been observed at levels exceeding 20 g/kg and 25 mg/L respectively due to the operation of a zinc recovery furnace during WWI. Erosion of the site due...

  9. Initial assessment of in-situ based soil moisture observations over Turkey

    NASA Astrophysics Data System (ADS)

    Bulut, Burak; Tugrul Yilmaz, M.; Cosh, Michael H.; Mladenova, Iliana

    2016-04-01

    Many hydrological applications are linked with water and energy balance equations. Given soil moisture is a common variable in both water and energy balance equations, it plays a critical role in many hydrological, atmospheric, and agricultural applications, like flood-, climate change-, land/atmosphere-, crop water requirement-related studies. This variable can be obtained using multiple platforms, like ground-based stations, remote sensing, and hydrological models. Among them station-based soil moisture observations arguably have the greatest role in estimating the true soil moisture values or the error characterization of remotely sensing- or hydrological model simulation-based values, even though station-based observations suffer from the sparsely located stations. Soil moisture has been observed in Turkey since 2007 over 149 stations, while the quality control of these stations have not been done before. In this study observed time-series have been quality controlled for their response to precipitation events and calibrated against the soil type and temperature of the soil medium. This study was supported by TUBITAK fund (#114Y676).

  10. Liparid and macrourid fishes of the hadal zone: in situ observations of activity and feeding behaviour.

    PubMed

    Jamieson, A J; Fujii, T; Solan, M; Matsumoto, A K; Bagley, P M; Priede, I G

    2009-03-22

    Using baited camera landers, the first images of living fishes were recorded in the hadal zone (6000-11000 m) in the Pacific Ocean. The widespread abyssal macrourid Coryphaenoides yaquinae was observed at a new depth record of approximately 7000 m in the Japan Trench. Two endemic species of liparid were observed at similar depths: Pseudoliparis amblystomopsis in the Japan Trench and Notoliparis kermadecensis in the Kermadec Trench. From these observations, we have documented swimming and feeding behaviour of these species and derived the first estimates of hadal fish abundance. The liparids intercepted bait within 100-200 min but were observed to preferentially feed on scavenging amphipods. Notoliparis kermadecensis act as top predators in the hadal food web, exhibiting up to nine suction-feeding events per minute. Both species showed distinctive swimming gaits: P. amblystomopsis (mean length 22.5 cm) displayed a mean tail-beat frequency of 0.47 Hz and mean caudal:pectoral frequency ratio of 0.76, whereas N. kermadecensis (mean length 31.5 cm) displayed respective values of 1.04 and 2.08 Hz. Despite living at extreme depths, these endemic liparids exhibit similar activity levels compared with shallow-water liparids.

  11. MAPIR: An Airborne Polarmetric Imaging Radiometer in Support of Hydrologic Satellite Observations

    NASA Technical Reports Server (NTRS)

    Laymon, C.; Al-Hamdan, M.; Crosson, W.; Limaye, A.; McCracken, J.; Meyer, P.; Richeson, J.; Sims, W.; Srinivasan, K.; Varnevas, K.

    2010-01-01

    In this age of dwindling water resources and increasing demands, accurate estimation of water balance components at every scale is more critical to end users than ever before. Several near-term Earth science satellite missions are aimed at global hydrologic observations. The Marshall Airborne Polarimetric Imaging Radiometer (MAPIR) is a dual beam, dual angle polarimetric, scanning L band passive microwave radiometer system developed by the Observing Microwave Emissions for Geophysical Applications (OMEGA) team at MSFC to support algorithm development and validation efforts in support of these missions. MAPIR observes naturally-emitted radiation from the ground primarily for remote sensing of land surface brightness temperature from which we can retrieve soil moisture and possibly surface or water temperature and ocean salinity. MAPIR has achieved Technical Readiness Level 6 with flight heritage on two very different aircraft, the NASA P-3B, and a Piper Navajo.

  12. Evaluation of Nimbus 7 SMMR sensor with airborne radiometers and surface observations in the Norwegian Sea

    NASA Technical Reports Server (NTRS)

    Gloersen, P.; Cavalieri, D.; Crawford, J.; Campbell, W. J.; Farrelly, B.; Johannessen, J.; Johannessen, O. M.; Svendsen, E.; Kloster, K.

    1981-01-01

    Measurements made by the Nimbus 7 SMMR are compared with near simultaneous observations using the airborne SMMR simulator and with surface observations. The area of the test is in the Norwegian Sea between Bear Island and Northern Norway. It is noted that during the observation period two low-pressure systems were located in the test area, giving a spatial wind variation from 3-20 m/s. It is shown that the use of the currently available brightness temperatures and algorithms for SMMR does not give universally satisfactory results for SST and wind speed under extreme weather conditions. In addition, the SMMR simulator results are seen as indicating the need for more work on calibration.

  13. Li Intercalation in MoS2: In Situ Observation of Its Dynamics and Tuning Optical and Electrical Properties.

    PubMed

    Xiong, Feng; Wang, Haotian; Liu, Xiaoge; Sun, Jie; Brongersma, Mark; Pop, Eric; Cui, Yi

    2015-10-14

    Two-dimensional layered materials like MoS2 have shown promise for nanoelectronics and energy storage, both as monolayers and as bulk van der Waals crystals with tunable properties. Here we present a platform to tune the physical and chemical properties of nanoscale MoS2 by electrochemically inserting a foreign species (Li(+) ions) into their interlayer spacing. We discover substantial enhancement of light transmission (up to 90% in 4 nm thick lithiated MoS2) and electrical conductivity (more than 200×) in ultrathin (∼2-50 nm) MoS2 nanosheets after Li intercalation due to changes in band structure that reduce absorption upon intercalation and the injection of large amounts of free carriers. We also capture the first in situ optical observations of Li intercalation in MoS2 nanosheets, shedding light on the dynamics of the intercalation process and the associated spatial inhomogeneity and cycling-induced structural defects.

  14. Fatigue crack growth behavior of a single crystal alloy as observed through an in situ fatigue loading stage

    NASA Technical Reports Server (NTRS)

    Telesman, Jack; Kantzos, Peter

    1988-01-01

    An in situ fatigue loading stage inside a scanning electron microscope (SEM) was used to determine the fatigue crack growth behavior of a PWA 1480 single-crystal nickel-based superalloy. The loading stage permits real-time viewing of the fatigue damage processes at high magnification. The PWA 1480 single-crystal, single-edge notch specimens were tested with the load axis parallel to the (100) orientation. Two distinct fatigue failure mechanisms were identified. The crack growth rate differed substantially when the failure occurred on a single slip system in comparison to multislip system failure. Two processes by which crack branching is produced were identified and are discussed. Also discussed are the observed crack closure mechanisms.

  15. In-Situ Observation of Crystallization and Growth in High-Temperature Melts Using the Confocal Laser Microscope

    NASA Astrophysics Data System (ADS)

    Sohn, Il; Dippenaar, Rian

    2016-08-01

    This review discusses the innovative efforts initiated by Emi and co-workers for in-situ observation of phase transformations at high temperatures for materials. By using the high-temperature confocal laser-scanning microscope (CLSM), a robust database of the phase transformation behavior during heating and cooling of slags, fluxes, and steel can be developed. The rate of solidification and the progression of solid-state phase transformations can be readily investigated under a variety of atmospheric conditions and be correlated with theoretical predictions. The various research efforts following the work of Emi and co-workers have allowed a deeper fundamental understanding of the elusive solidification and phase transformation mechanisms in materials beyond the ambit of steels. This technique continues to evolve in terms of its methodology, application to other materials, and its contribution to technology.

  16. Fatique crack growth behavior of a single crystal alloy as observed through an in situ fatigue loading stage

    NASA Technical Reports Server (NTRS)

    Telesman, Jack; Kantzos, Peter

    1988-01-01

    An in situ fatigue loading stage inside a scanning electron microscope (SEM) was used to determine the fatigue crack growth behavior of a PWA 1480 single-crystal nickel-based superalloy. The loading stage permits real-time viewing of the fatigue damage processes at high magnification. The PWA 1480 single-crystal, single-edge notch specimens were tested with the load axis parallel to the (100) orientation. Two distinct fatigue failure mechanisms were identified. The crack growth rate differed substantially when the failure occurred on a single slip system in comparison to multislip system failure. Two processes by which crack branching is produced were identified and are discussed. Also discussed are the observed crack closure mechanisms.

  17. Copper silicide/silicon nanowire heterostructures: in situ TEM observation of growth behaviors and electron transport properties.

    PubMed

    Chiu, Chung-Hua; Huang, Chun-Wei; Chen, Jui-Yuan; Huang, Yu-Ting; Hu, Jung-Chih; Chen, Lien-Tai; Hsin, Cheng-Lun; Wu, Wen-Wei

    2013-06-01

    Copper silicide has been studied in the applications of electronic devices and catalysts. In this study, Cu3Si/Si nanowire heterostructures were fabricated through solid state reaction in an in situ transmission electron microscope (TEM). The dynamic diffusion of the copper atoms in the growth process and the formation mechanism are characterized. We found that two dimensional stacking faults (SF) may retard the growth of Cu3Si. Due to the evidence of the block of edge-nucleation (heterogeneous) by the surface oxide, center-nucleation (homogeneous) is suggested to dominate the silicidation. Furthermore, the electrical transport properties of various silicon channel length with Cu3Si/Si heterostructure interfaces and metallic Cu3Si NWs have been investigated. The observations not only provided an alternative pathway to explore the formation mechanisms and interface properties of Cu3Si/Si, but also suggested the potential application of Cu3Si at nanoscale for future processing in nanotechnology.

  18. In-situ observation of inhomogeneous degradation in large format Li-ion cells by neutron diffraction

    SciTech Connect

    Cai, Lu; An, Ke; Feng, Zhili; Liang, Chengdu; Harris, Stephen J.

    2013-08-01

    This work presents a non-destructive in-situ method for probing degradation mechanisms in large format, operating, commercial lithium-ion batteries by neutron diffraction. A fresh battery (15 Ah capacity) was shown to have a uniform (homogeneous) local state of charge (SOC) at 4.0 V (9 Ah SOC) and 4.2 V (15 Ah SOC), with 1.33 C and 2.67 C charging rates, respectively. This battery was then aggressively cycled until it retained only a 9 Ah capacity, 60% of its original value. Inhomogeneous deterioration in the battery was observed: near the edges, both the graphite anode and the spinel-based cathode showed a significant loss of capacity, while near the central area, both electrodes functioned properly. An SOC mapping measurement of the degraded battery in the fully charged state (4.2 V) indicated that the loss of local capacity of the anode and cathode is coupled.

  19. In-situ observation of self-regulated switching behavior in WO{sub 3-x} based resistive switching devices

    SciTech Connect

    Hong, D. S.; Wang, W. X.; Chen, Y. S. Sun, J. R.; Shen, B. G.

    2014-09-15

    The transmittance of tungsten oxides can be adjusted by oxygen vacancy (V{sub o}) concentration due to its electrochromic property. Here, we report an in-situ observation of resistive switching phenomenon in the oxygen-deficient WO{sub 3-x} planar devices. Besides directly identifying the formation/rupture of dark-colored conductive filaments in oxide layer, the stripe-like WO{sub 3-x} device demonstrated self-regulated switching behavior during the endurance testing, resulting in highly consistent switching parameters after a stabilizing process. For very high V{sub o}s mobility was demonstrated in the WO{sub 3-x} film by the pulse experiment, we suggested that the electric-field-induced homogeneous migration of V{sub o}s was the physical origin for such unique switching characteristics.

  20. Evaluation of four global reanalysis products using in situ observations in the Amundsen Sea Embayment, Antarctica

    NASA Astrophysics Data System (ADS)

    Jones, R. W.; Renfrew, I. A.; Orr, A.; Webber, B. G. M.; Holland, D. M.; Lazzara, M. A.

    2016-06-01

    The glaciers within the Amundsen Sea Embayment (ASE), West Antarctica, are amongst the most rapidly retreating in Antarctica. Meteorological reanalysis products are widely used to help understand and simulate the processes causing this retreat. Here we provide an evaluation against observations of four of the latest global reanalysis products within the ASE region—the European Centre for Medium-Range Weather Forecasts Interim Reanalysis (ERA-I), Japanese 55-year Reanalysis (JRA-55), Climate Forecast System Reanalysis (CFSR), and Modern Era Retrospective-Analysis for Research and Applications (MERRA). The observations comprise data from four automatic weather stations (AWSs), three research vessel cruises, and a new set of 38 radiosondes all within the period 2009-2014. All four reanalyses produce 2 m temperature fields that are colder than AWS observations, with the biases varying from approximately -1.8°C (ERA-I) to -6.8°C (MERRA). Over the Amundsen Sea, spatially averaged summertime biases are between -0.4°C (JRA-55) and -2.1°C (MERRA) with notably larger cold biases close to the continent (up to -6°C) in all reanalyses. All four reanalyses underestimate near-surface wind speed at high wind speeds (>15 m s-1) and exhibit dry biases and relatively large root-mean-square errors (RMSE) in specific humidity. A comparison to the radiosonde soundings shows that the cold, dry bias at the surface extends into the lower troposphere; here ERA-I and CFSR reanalyses provide the most accurate profiles. The reanalyses generally contain larger temperature and humidity biases, (and RMSE) when a temperature inversion is observed, and contain larger wind speed biases (~2 to 3 m s-1), when a low-level jet is observed.

  1. In situ observation of the Cardinium symbionts of Brevipalpus (Acari: Tenuipalpidae) by electron microscopy.

    PubMed

    Kitajima, Elliot W; Groot, Thomas V M; Novelli, Valdenice M; Freitas-Astúa, Juliana; Alberti, Gerd; de Moraes, Gilberto J

    2007-01-01

    Brevipalpus (Acari: Tenuipalpidae) mites are important pests on a variety of host plant species. The mites damage their hosts directly by feeding and some species also serve as vectors of plant viruses. Among more than 200 described Brevipalpus species, three are recognized as vectors of plant viruses: B. phoenicis, B. californicus and B. obovatus. These species occur worldwide in subtropical and tropical regions. Brevipalpus mites reproduce mostly by thelytokous parthenogenesis and this condition was attributed to a bacterial endosymbiont, recently characterized as a member of the genus Cardinium. The same symbiont infects many other arthropods and is capable of manipulating their host reproduction in various ways. Generally the presence of Cardinium is determined by molecular, PCR based, techniques. In the current work we present visual evidence for the presence of these bacteria by transmission electron microscopy as a complement of previous detection by PCR. Cardinium is easily identified by the presence of a unique array of microtubule-like structures (ML) in the cell. Symbionts have been observed in several organs and eggs from different populations of all three Brevipalpus species known as vector of plant viruses. Cardinium cells were always immersed directly within the cytoplasm of infected cells. Bacteria were observed in all females of all instars, but were absent from all males examined. Females from some Brevipalpus populations were observed to be uninfected by Cardinium. This observation confirmed previous PCR-based results that these populations were aposymbiotic. The observed distribution of the bacteria suggests that these bacteria could have other functions in the mite biology beside feminization.

  2. In situ observation of the Cardinium symbionts of Brevipalpus (Acari: Tenuipalpidae) by electron microscopy.

    PubMed

    Kitajima, Elliot W; Groot, Thomas V M; Novelli, Valdenice M; Freitas-Astúa, Juliana; Alberti, Gerd; de Moraes, Gilberto J

    2007-01-01

    Brevipalpus (Acari: Tenuipalpidae) mites are important pests on a variety of host plant species. The mites damage their hosts directly by feeding and some species also serve as vectors of plant viruses. Among more than 200 described Brevipalpus species, three are recognized as vectors of plant viruses: B. phoenicis, B. californicus and B. obovatus. These species occur worldwide in subtropical and tropical regions. Brevipalpus mites reproduce mostly by thelytokous parthenogenesis and this condition was attributed to a bacterial endosymbiont, recently characterized as a member of the genus Cardinium. The same symbiont infects many other arthropods and is capable of manipulating their host reproduction in various ways. Generally the presence of Cardinium is determined by molecular, PCR based, techniques. In the current work we present visual evidence for the presence of these bacteria by transmission electron microscopy as a complement of previous detection by PCR. Cardinium is easily identified by the presence of a unique array of microtubule-like structures (ML) in the cell. Symbionts have been observed in several organs and eggs from different populations of all three Brevipalpus species known as vector of plant viruses. Cardinium cells were always immersed directly within the cytoplasm of infected cells. Bacteria were observed in all females of all instars, but were absent from all males examined. Females from some Brevipalpus populations were observed to be uninfected by Cardinium. This observation confirmed previous PCR-based results that these populations were aposymbiotic. The observed distribution of the bacteria suggests that these bacteria could have other functions in the mite biology beside feminization. PMID:17634867

  3. In situ observation of water behavior at the surface and buried interface of a low-k dielectric film.

    PubMed

    Zhang, Xiaoxian; Myers, John N; Bielefeld, Jeffery D; Lin, Qinghuang; Chen, Zhan

    2014-11-12

    Water adsorption in porous low-k dielectrics has become a significant challenge for both back-end-of-line integration and reliability. A simple method is proposed here to achieve in situ observation of water structure and water-induced structure changes at the poly(methyl silsesquioxane) (PMSQ) surface and the PMSQ/solid buried interface at the molecular level by combining sum frequency generation (SFG) vibrational spectroscopic and Fourier transform infrared (FTIR) spectroscopic studies. First, in situ SFG investigations of water uptake were performed to provide direct evidence that water diffuses predominantly along the PMSQ/solid interface rather than through the bulk. Furthermore, SFG experiments were conducted at the PMSQ/water interface to simulate water behavior at the pore inner surfaces for porous low-k materials. Water molecules were found to form strong hydrogen bonds at the PMSQ surface, while weak hydrogen bonding was observed in the bulk. However, both strongly and weakly hydrogen bonded water components were detected at the PMSQ/SiO2 buried interface. This suggests that the water structures at PMSQ/solid buried interfaces are also affected by the nature of solid substrate. Moreover, the orientation of the Si-CH3 groups at the buried interface was permanently changed by water adsorption, which might due to low flexibility of Si-CH3 groups at the buried interface. In brief, this study provides direct evidence that water molecules tend to strongly bond (chemisorbed) with low-k dielectric at pore inner surfaces and at the low-k/solid interface of porous low-k dielectrics. Therefore, water components at the surfaces, rather than the bulk, are likely more responsible for chemisorbed water related degradation of the interconnection layer. Although the method developed here was based on a model system study, we believe it should be applicable to a wide variety of low-k materials.

  4. In situ observations of a high-pressure phase of H2O ice

    USGS Publications Warehouse

    Chou, I.-Ming; Blank, J.G.; Goncharov, A.F.; Mao, Ho-kwang; Hemley, R.J.

    1998-01-01

    A previously unknown solid phase of H2O has been identified by its peculiar growth patterns, distinct pressure-temperature melting relations, and vibrational Raman spectra. Morphologies of ice crystals and their pressure-temperature melting relations were directly observed in a hydrothermal diamond-anvil cell for H2O bulk densities between 1203 and 1257 kilograms per cubic meter at temperatures between -10??and 50??C. Under these conditions, four different ice forms were observed to melt: two stable phases, ice V and ice VI, and two metastable phases, ice IV and the new ice phase. The Raman spectra and crystal morphology are consistent with a disordered anisotropic structure with some similarities to ice VI.

  5. In situ observation of thermal relaxation of interstitial-vacancy pair defects in a graphite gap.

    PubMed

    Urita, Koki; Suenaga, Kazu; Sugai, Toshiki; Shinohara, Hisanori; Iijima, Sumio

    2005-04-22

    Direct observation of individual defects during formation and annihilation in the interlayer gap of double-wall carbon nanotubes (DWNT) is demonstrated by high-resolution transmission electron microscopy. The interlayer defects that bridge two adjacent graphen layers in DWNT are stable for a macroscopic time at the temperature below 450 K. These defects are assigned to a cluster of one or two interstitial-vacancy pairs (I-V pairs) and often disappear just after their formation at higher temperatures due to an instantaneous recombination of the interstitial atom with vacancy. Systematic observations performed at the elevated temperatures find a threshold for the defect annihilation at 450-500 K, which, indeed, corresponds to the known temperature for the Wigner energy release. PMID:15904158

  6. Fast printing and in situ morphology observation of organic photovoltaics using slot-die coating.

    PubMed

    Liu, Feng; Ferdous, Sunzida; Schaible, Eric; Hexemer, Alexander; Church, Matthew; Ding, Xiaodong; Wang, Cheng; Russell, Thomas P

    2015-02-01

    The mini-slot-die coater offers a simple, convenient, materials-efficient route to print bulk-heterojunction (BHJ) organic photovoltaics (OPVs) that show efficiencies similar to spin-coating. Grazing-incidence X-ray diffraction (GIXD) and GI small-angle X-ray scattering (GISAXS) methods are used in real time to characterize the active-layer formation during printing. A polymer-aggregation-phase-separation-crystallization mechanism for the evolution of the morphology describes the observations.

  7. Fishes of the hadal zone including new species, in situ observations and depth records of Liparidae

    NASA Astrophysics Data System (ADS)

    Linley, Thomas D.; Gerringer, Mackenzie E.; Yancey, Paul H.; Drazen, Jeffrey C.; Weinstock, Chloe L.; Jamieson, Alan J.

    2016-08-01

    Observations and records for fish exceeding 6000 m deep are few and often spurious. Recent developments in accessing and sampling the hadal zone 6000-11,000 m) have led to an acceleration in new findings in the deep subduction trenches, particularly in the Pacific Ocean. This study describes the discovery of two new species of snailfish (Liparidae) from the Mariana Trench; the 'Mariana snailfish' (6198-8076 m) and the 'Ethereal snailfish' (7939-8145 m). These new findings represent respectively the deepest known specimen caught with corroborating depth data, and the deepest fish seen alive. Further specimens and observations of the Kermadec Trench snailfish, Notoliparis kermadecensis, are also presented, as well as the first hadal records of Synaphobranchidae and Zoarcidae (6068 and 6145 m respectively) and a depth extension for the Macrouridae (maximum depth now 7012 m). Details of these new snailfish specimens caught by baited trap and behaviour observations filmed by baited cameras are presented. An updated assessment of fishes from hadal depths is also reported.

  8. In-situ Observations of Gamma-ray Production in Thunderstorms

    NASA Astrophysics Data System (ADS)

    Eack, Kenneth; Aulich, Graydon; Winn, William; Edens, Harald

    2016-04-01

    The majority of the reported observations of energetic radiation from thunderstorms have come from either ground-based or satellite-based measurements. In order to better understand the physical conditions necessary for the production of fast electrons and gamma-rays, measurements are needed near the production regions inside or above the thunderstorm. Three different measurements are of particular interest. First, gamma-rays produced by the quasi-static electric-field may provide details about the physics of runaway electrons that would be difficult to determine from measurements of transient phenomena, such as lightning and terrestrial gamma-ray flashes (TGFs). Second, what process inside the thunderstorm is responsible for TGFs? Recent ground-bsed studies have pointed to the upward negative leader in inter-cloud lightning as a possible source. Finally, the initiation of lightning appears to be a problem in light of the relatively weak (about 10% of the classical breakdown threshold) electric fields observed inside thunderstorms. Since these field strengths are adequate for runaway electrons, they have been proposed as a possible source for the initial breakdown in lightning. In this paper, we will present observations from balloon-borne gamma-ray detectors and electric-field sensors, as well as ground based instruments like the lightning mapping array (LMA) in effort to examine these areas of interest.

  9. Using Lidar, in-situ measurements and Trajectory Analysis to observe air pollution in Beijing, 2014

    NASA Astrophysics Data System (ADS)

    Chen, Zhenyi; Liu, Wenqing; Liu, Jianguo; Zhang, Tianshu; Dong, Yunsheng

    2016-06-01

    We present combined Mie lidar, ozone lidar and wide-range particle spectrometer observations that were carried out in Beijing, north China during two periods—one haze period before the Asia-Pacific Economic Cooperation (APEC) meeting and one moderate pollution period during the meeting in 2014. High extinction coefficient, moderate ozone concentration and variable particle number concentration were obtained throughout the first haze observation period. The mean extinction coefficients in the two pollution periods were 0.52 km-1 and 0.23 km-1, respectively, at 532 nm. The ozone concentration during the first haze phase was more various with higher average value of 49 ppb compared to that in the second pollution observations (32 ppb). The comparison of aerosols and ozone in different heights indicate different pollution sources and complicated ozone process of generation and disappearance. The four-day back trajectories from a HYSPLIT model indicate that the air masses in the lower boundary layer were advected from the densely populated south regions of China and the long pollution transportation passing through northern China.

  10. Exploring the potential of combining column-integrated atmospheric polarization with airborne in situ size distribution measurements for the retrieval of an aerosol model: A case study of a biomass burning plume during SAFARI 2000

    NASA Astrophysics Data System (ADS)

    Elias, Thierry; Piketh, Stuart J.; Burger, Roelof; Silva, Ana Maria

    2003-07-01

    Ground-based columnar and airborne in situ measurements of aerosol optical properties acquired during the Southern African Regional Science Initiative (SAFARI 2000) in August-September 2000 are analyzed to retrieve the aerosol model of a haze layer affected by long-range transport of biomass burning emissions. One case study is considered. A columnar value of the aerosol polarized phase function Qmeasp(Θ) and of the aerosol single scattering albedo ω0, both at 870 nm, are retrieved from measurements acquired by a ground-based Sun/sky photometer, assuming that the surface albedo is 0.3. The maximum value of the polarized phase function is 0.37 ± 0.02 at a scattering angle of 70°, ω0 is 0.80 ± 0.05. The in situ particle size distribution is measured in a vertical profile over the ground-based site by an airborne optical particle counter. Because the size distribution integrated over the column is inconsistent with the polarized phase function, aerosol concentration of the 0.25 μm mode is reduced by a factor of 7.5. Taking into account that the estimation of particle size depends on particle refractive index, it is found that the radius of absorbing particles cannot be larger than 0.15 μm for reproducing Qmeasp(Θ), suggesting external mixture of absorbing particles smaller than 0.15 μm with nonabsorbing particles larger than 0.15 μm. The imaginary part of the effective refractive index is estimated to be (0.09 ± 0.03)i. Comparing Ångström exponent obtained from Sun/sky photometer extinction measurements and the Ångström exponent calculated for the in situ measured aerosol size distribution acquired in eleven vertical profiles allows us to conclude that in most considered cases, the mixture of absorbing with nonabsorbing particles is external with a radius limit at around 0.15 μm.

  11. Cluster observations of the plasma sheet at very high latitudes: The in situ signature of a transpolar arc

    NASA Astrophysics Data System (ADS)

    Fear, R. C.; Milan, S. E.; Maggiolo, R.

    2013-12-01

    Transpolar arcs are auroral features which extend into the polar cap, which is the dim region poleward of the main auroral oval. Several case and statistical studies have shown that they are formed by the closure of lobe magnetic flux by magnetotail reconnection, and that the transpolar arc forms at the footprints of the newly-closed field lines which are embedded within the open flux of the polar cap. Therefore, when transpolar arcs occur, the magnetotail should contain closed magnetic field lines even at high latitudes (but in a localised sector), embedded within the open lobe flux. We present in situ observations of this phenomenon, taken by the Cluster spacecraft on 15th September 2005. Cluster was located at high latitudes in the southern hemisphere lobe (far from the typical location of the plasma sheet), and a transpolar arc was observed by the FUV cameras on the IMAGE satellite. An initial analysis reveals that Cluster periodically observed plasma similar to a typical plasma sheet distribution, but at much higher latitudes - indicative of closed flux embedded within the high latitude lobe. Each time that this plasma distribution was observed, the footprint of the spacecraft mapped to the transpolar arc (significantly poleward of the main auroral oval). These observations are consistent with closed flux being trapped in the magnetotail and embedded within the lobe, and provide further evidence for transpolar arcs being formed by magnetotail reconnection.

  12. Intraannual variability of tides in the thermosphere from model simulations and in situ satellite observations

    NASA Astrophysics Data System (ADS)

    Häusler, K.; Hagan, M. E.; Forbes, J. M.; Zhang, X.; Doornbos, E.; Bruinsma, S.; Lu, G.

    2015-01-01

    In this paper, we provide insights into limitations imposed by current satellite-based strategies to delineate tidal variability in the thermosphere, as well as the ability of a state-of-the-art model to replicate thermospheric tidal determinations. Toward this end, we conducted a year-long thermosphere-ionosphere-mesosphere-electrodynamics general circulation model (TIME-GCM) simulation for 2009, which is characterized by low solar and geomagnetic activity. In order to account for tropospheric waves and tides propagating upward into the ˜30-400 km model domain, we used 3-hourly MERRA (Modern-Era Retrospective Analysis for Research and Application) reanalysis data. We focus on exospheric tidal temperatures, which are also compared with 72 day mean determinations from combined Challenging Minisatellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE) satellite observations to assess the model's capability to capture the observed tidal signatures and to quantify the uncertainties associated with the satellite exospheric temperature determination technique. We found strong day-to-day tidal variability in TIME-GCM that is smoothed out when averaged over as few as ten days. TIME-GCM notably overestimates the 72 day mean eastward propagating tides observed by CHAMP/GRACE, while capturing many of the salient features of other tidal components. However, the CHAMP/GRACE tidal determination technique only provides a gross climatological representation, underestimates the majority of the tidal components in the climatological spectrum, and moreover fails to characterize the extreme variability that drives the dynamics and electrodynamics of the ionosphere-thermosphere system. A multisatellite mission that samples at least six local times simultaneously is needed to provide this quantification.

  13. Improving carbon cycle models using inverse modelling techniques with in-situ measurements and satellite observations

    NASA Astrophysics Data System (ADS)

    Delahaies, Sylvain; Roulstone, Ian; Nichols, Nancy

    2014-05-01

    Improving our understanding of the carbon cycle is an important component of modelling climate and the Earth system, and a variety of inverse modelling techniques have been used to combine process models with different types of observational data. Model data fusion, or inverse modelling, is the process of best combining our under- standing of the dynamics of a system, observations and our prior knowledge of the state of the system. We consider a simple model for the carbon budget allocation for terrestrial ecosystems, the Data Assimilation-Linked Ecosystem model (DALEC). DALEC is a box model simulating a large range of processes occurring at different time scales from days to millennia. Eddy covariance measurements of net ecosystem exchange of CO2 have been used intensively for over a decade to confront DALEC with real data to estimate model parameters and quantify uncertainty of the model predictions. The REgional FLux Estimation eXperiment (REFLEX), compared the strengths and weaknesses of various inverse modelling strategies (MCMC, ENKF) to estimate parameters and initial stocks for DALEC; most results agreed on the fact that parameters and initial stocks directly related to fast processes were best estimated with narrow confidence intervals, whereas those related to slow processes were poorly estimated with very large uncertainties. While other studies have tried to overcome this difficulty by adding complementary data streams or by considering longer observation windows no systematic analysis has been carried out so far to explain the large differences among results of REFLEX. One of the merits of DALEC is its simplicity that facilitates close mathematical scrutiny. Using variational techniques we quantify the ill-posedness of the inverse problem and we discuss various regularisation techniques. Using the tangent linear model we study the information content of multiple data sources and show how these multiple data sources help constraining initial carbon

  14. In-situ Observations of Mid-latitude Forest Fire Plumes Deep in the Stratosphere

    NASA Technical Reports Server (NTRS)

    Jost, Hans-Juerg; Drdla, Katja; Stohl, Andreas; Pfister, Leonhard; Loewenstein, Max; Lopez, Jimena P.; Hudson, Paula K.; Murphy, Daniel M.; Cziczo, Daniel J.; Fromm, Michael

    2004-01-01

    We observed a plume of air highly enriched in carbon monoxide and particles in the stratosphere at altitudes up to 15.8 km. It can be unambiguously attributed to North American forest fires. This plume demonstrates an extratropical direct transport path from the planetary boundary layer several kilometers deep into the stratosphere, which is not fully captured by large-scale atmospheric transport models. This process indicates that the stratospheric ozone layer could be sensitive to changes in forest burning associated with climatic warming.

  15. In-Situ TEM-STM Observations of SWCNT Ropes/Tubular Transformations

    NASA Technical Reports Server (NTRS)

    Sola, F.; Lebron-Colon, M.; Ferreira, P. J.; Fonseca, L. F.; Meador, M. A.; Marin, C.

    2010-01-01

    Single-walled carbon nanotubes (SWCNTs) prepared by the HiPco process were purified using a modified gas phase purification technique. A TEM-STM holder was used to study the morphological changes of SWCNT ropes as a function of applied voltage. Kink formation, buckling behavior, tubular transformation and eventual breakdown of the system were observed. The tubular formation was attributed to a transformation from SWCNT ropes to multi-walled carbon nanotube (MWCNT) structures. It is likely mediated by the patching and tearing mechanism which is promoted primarily by the mobile vacancies generated due to current-induced heating and, to some extent, by electron irradiation.

  16. Nanocrystal Diffusion in a Liquid Thin Film Observed by in situ Transmission Electron Microscopy

    SciTech Connect

    Zheng, Haimei; Claridge, Shelley A.; Minor, Andrew M.; Alivisatos, A. Paul; Dahmen, Ulrich

    2009-04-17

    We have directly observed motion of inorganic nanoparticles during fluid evaporation using a Transmission Electron Microscope. Tracking real-time diffusion of both spherical (5-15 nm) and rod-shaped (5x10 nm) gold nanocrystals in a thin-film of water-15percentglycerol reveals complex movements, such as rolling motions coupled to large-step movements and macroscopic violations of the Stokes-Einstein relation for diffusion. As drying patches form during the final stages of evaporation, particle motion is dominated by the nearby retracting liquid front.

  17. Determining the Coronal Origins of the Solar Wind Using Remote Sensing and In Situ Observations

    NASA Astrophysics Data System (ADS)

    Miralles, Mari Paz

    2013-05-01

    We study the origin and evolution of the solar wind by characterizing the physical properties of the solar wind plasma with multi-spacecraft (Hinode, SDO, SOHO, STEREO, ACE, Ulysses, WIND) and ground-based (MLSO, MWO, NSO, WSO) observations. We discuss the results for the fast solar wind from polar and low-latitude coronal-hole wind streams and for the slow wind from coronal-streamer wind streams. We also compare the characteristics of these wind streams with results from the previous solar cycle. This work is supported by NASA grant NNX10AQ58G to the Smithsonian Astrophysical Observatory.

  18. In-Situ Observations of Phase Transformations in the HAZ of 2205 Duplex Stainless Steel Weldments

    SciTech Connect

    Palmer, T A; Elmer, J W; Wong, J

    2001-08-15

    Ferrite ({delta})/austenite ({gamma}) transformations in the heat affected zone (HAZ) of a gas tungsten arc (GTA) weld in 2205 duplex stainless steel are observed in real-time using spatially resolved X-ray diffraction (SRXRD) with high intensity synchrotron radiation. A map showing the locations of the {delta} and {gamma} phases with respect to the calculated weld pool dimensions has been constructed from a series of SRXRD scans. Regions of liquid, completely transformed {gamma}, a combination of partially transformed {gamma} with untransformed {delta}, and untransformed {delta}+{gamma} are identified. Analysis of each SRXRD pattern provides a semi-quantitative definition of both the {delta}/{gamma} phase balance and the extent of annealing which are mapped for the first time with respect to the calculated weld pool size and shape. A combination of these analyses provides a unique real-time description of the progression of phase transformations in the HAZ. Using these real-time observations, important kinetic information about the transformations occurring in duplex stainless steels during heating and cooling cycles typical of welding can be determined.

  19. Remote sensing and in situ observations of marine slicks associated with inhomogeneous coastal currents

    NASA Astrophysics Data System (ADS)

    Ermakov, S.; Kapustin, I.; Sergievskaya, I.

    2011-11-01

    Field observations co-located and simultaneous with satellite radar imagery of biogenic slick bands on the sea surface aimed to study relation between slicks and marine stream currents were carried out in the coastal zone of the Black Sea. Measurements of the current velocities at different depths were performed using an acoustic Doppler current profiler (ADCP) and surface floats. Samples of surfactant films inside/outside slick bands were collected from the water surface with nets. The sampled films were reconstructed in laboratory conditions and measurements of the damping coefficient of gravity-capillary waves and the surface tension were carried out using an original parametric wave method. It is obtained that the banded slicks are characterized by enhanced concentration of surfactants due to their compression by convergent current components. The slicks are revealed to be oriented along the stream currents and are located in the zones of current shears. Small convergent transverse velocity components are observed near slick boundaries and are responsible for slick formation in stream shear currents. Different examples of slicks formed by stream shear current are described. Results of a case study of two streams of different directions merging and forming a banded slick in a shear zone with convergent transverse current components are presented. Another case study is when a flow below a thermocline coming to the shore meets a bottom slope and a vertical current occurs resulting in horizontal divergence and convergence on the surface.

  20. In situ observations of soil minerals and organic matter in the early phases of prescribed fires

    NASA Astrophysics Data System (ADS)

    Kavouras, Ilias G.; Nikolich, George; Etyemezian, Vic; Dubois, David W.; King, James; Shafer, David

    2012-06-01

    We examined the chemical composition of aerosol samples collected during a prescribed fire at a Great Basin Desert site in the context of samples collected from controlled combustion of vegetation clippings from the same site and resuspension of soil samples obtained prior to and after the burn event. We observed a distinct difference in the composition of organic carbon resuspended soil dust after the burn, reflecting changes caused by the heating of the soil. The relative abundances of minerals and organic carbon fractions in aerosols collected during the first period of the burn were identical to those measured in soil dust. For aerosol samples collected for the remaining two periods of the burn event, the profiles of both minerals and organic carbon matched quite well those observed for vegetation combustion. Reconstruction of aerosol samples collected during the burn event showed that vegetation combustion dominated emissions but mineral soil dust may account for about 10% of PM10emissions (reconstructed) during the early stages of the fire. A large fraction of emissions during the first two hours was also unaccounted mainly because of the insufficient conversion of organic carbon to organic mass. The abundance of heavier non-volatile organics in soil dust suggested the presence of humic/fulvic acids that exhibit higher OM-to-OC ratios and thus, account for a proportion of the unaccounted emissions. These findings indicated that soil dust may be released into the air during a fire event, probably due to the enhanced turbulent mixing near the burn front.

  1. In situ Observations of CIRs on STEREO, Wind, and ACE During 2007 - 2008

    NASA Astrophysics Data System (ADS)

    Mason, G. M.; Desai, M. I.; Mall, U.; Korth, A.; Bucik, R.; von Rosenvinge, T. T.; Simunac, K. D.

    2009-05-01

    During the 2007 and 2008 solar minimum period, STEREO, Wind, and ACE observed numerous Corotating Interaction Regions (CIRs) over spatial separations that began with all the spacecraft close to Earth, through STEREO separation angles of ˜ 80 degrees in the fall of 2008. Over 35 CIR events were of sufficient intensity to allow measurement of He and heavy ion spectra using the IMPACT/SIT, EPACT/STEP and ACE/ULEIS instruments on STEREO, Wind, and ACE, respectively. In addition to differences between the spacecraft expected on the basis of simple corotation, we observed several events where there were markedly different time-intensity profiles from one spacecraft to the next. By comparing the energetic particle intensities and spectral shapes along with solar wind speed we examine the extent to which these differences are due to temporal evolution of the CIR or due to variations in connection to a relatively stable interaction region. Comparing CIRs in the 1996 - 1997 solar minimum period vs. 2007 - 2008, we find that the 2007 - 2008 period had many more CIRs, reflecting the presence of more high-speed solar wind streams, whereas 1997 had almost no CIR activity.

  2. In situ observation of magnetic reconnection in the front of bursty bulk flow

    NASA Astrophysics Data System (ADS)

    Wang, Rongsheng; Lu, Quanming; Du, Aimin; Nakamura, Rumi; Lu, San; Huang, Can; Liu, Chaoxu; Wu, Mingyu

    2014-12-01

    Using the Cluster observation in the magnetotail, we investigate the dynamic processes associated with a bursty bulk flow (BBF) event. The BBF is inferred to be caused by magnetic reconnection proceeding to the lobe region in its tail, called "primary reconnection." On the BBF front, another reconnection was directly encountered by one of the four Cluster satellites, and no signatures of this reconnection were simultaneously measured by the satellite at the plasma sheet boundary. It indicates that this reconnection on the BBF front remained within the plasma sheet, called "secondary reconnection." The secondary reconnection moved earthward and was followed by a magnetic island. A few earthward moving pulses of Bz were detected between the island and the primary reconnection site. These Bz pulses, propagating faster than the island ahead of it, would lead to a more compressed Bz magnetic field in the wake of the island. The observational scenario is in accordance to the model proposed to explain the generation of dipolarization front in simulations. Furthermore, both electrons and ions were significantly accelerated in this process. The mechanism is discussed also.

  3. First multipoint in situ observations of electron microbursts: Initial results from the NSF FIREBIRD II mission

    NASA Astrophysics Data System (ADS)

    Crew, Alexander B.; Spence, Harlan E.; Blake, J. Bernard; Klumpar, David M.; Larsen, Brian A.; O'Brien, T. Paul; Driscoll, Shane; Handley, Matthew; Legere, Jason; Longworth, Stephen; Mashburn, Keith; Mosleh, Ehson; Ryhajlo, Nicholas; Smith, Sonya; Springer, Larry; Widholm, Mark

    2016-06-01

    We present initial dual spacecraft observations that for the first time both constrain the spatial scale size and provide spectral properties at medium energies of electron microbursts. We explore individual microburst events that occurred on 2 February 2015 using simultaneous observations made by the twin CubeSats which comprise the National Science Foundation (NSF) Focused Investigations of Relativistic Electron Bursts: Intensity, Range, and Dynamics (FIREBIRD II). During these microburst events, the two identically instrumented FIREBIRD II CubeSats were separated by as little as 11 km while traversing electron precipitation regions in low-Earth orbit. These coincident microburst events map to size scales >120 km at the equator. Given the prevalence of coincident and noncoincident events we conclude that this is of the same order of magnitude as that of the spatial scale size of electron microburst, an unknown property that is critical for quantifying their overall role in radiation belt dynamics. Finally, we present measurements of electron microbursts showing that precipitation often occurs simultaneously across a broad energy range spanning 200 keV to 1 MeV, a new form of empirical evidence that provides additional insights into the physics of microburst generation mechanisms.

  4. In situ observations of fish associated with coral reefs off Ireland

    NASA Astrophysics Data System (ADS)

    Söffker, M.; Sloman, K. A.; Hall-Spencer, J. M.

    2011-08-01

    The abundance and behaviour of fish on and around coral reefs at Twin Mounds and Giant Mounds, carbonate mounds located on the continental shelf off Ireland (600-1100 m), were studied using two Remotely Operated Vehicle (ROV) dives. We recorded 30 fish taxa on the dives, together with three species of Scleractinia ( Lophelia pertusa, Madrepora oculata and Desmophyllum cristagalli) and a diverse range of other corals (Antipatharia, Alcyonacea, and Stylasteridae). Stands of live coral provided the only habitat in which Guttigadus latifrons was observed whereas Neocyttus helgae was found predominantly on structural habitats provided by dead coral. Significantly more fish were found on structurally complex coral rubble habitats than on flatter areas where coral rubble was clogged with sand. The most common species recorded was Lepidion eques (2136 individuals), which always occurred a few cm above bottom and was significantly more active on the reefs than on sedimentary habitats. Synaphobranchus kaupii (1157 indiv.) , N. helgae (198 indiv.) and Micromesistius poutassou (116 indiv.) were also common; S. kaupii did not exhibit habitat-related differences in behaviour, whilst N. helgae was more active over the reefs and other structured habitats whereas M. poutassou was more active with decreasing habitat complexity. Trawl damage and abandoned fishing gear was observed at both sites. We conclude that Irish coral reefs provide complex habitats that are home to a diverse assemblage of fish utilising the range of niches occurring both above and within the reef structure.

  5. In situ observation of harmful dinoflagellate bloom in the eastern coast of Kyushu, Japan

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Hisashi; Murakami, Hirishi; Miyamura, Kazuyoshi; Siawanto, Eko; Kobayashi, Hiroshi; Ishizaka, Joji

    2014-05-01

    Oita coast, where is in the eastern coast of Kyushu, Japan, is a richly fish aquaculture area. However, sometimes harmful algal blooms occur in this region, especially harmful dinoflagellates blooms, and cultured fish mortality occurs. Ocean color remote sensing is expected as a useful tool to reduce the financial damage of harmful algal blooms. However, ocean color data is low accuracy in the coastal region because colored dissolved organic matter and suspended solid are dominant. More optical data of harmful algal blooms are required because there are few data in harmful algal blooms. The field observation was conducted to understand the inherent optical property of harmful dinoflagellate bloom in the eastern coast of Oita prefecture on April and August 2013. Chlorophyll-a maximum (>24 mg m^-3) was observed in the subsurface layer on April 2013. The dominant phytoplankton species in this chlorophyll-a maximum layer was dinoflagellate Cochlodinium polykrikoides (>300 cells ml^-1) and early stage of the bloom was formed. Peak of the remote sensing reflectance was near 565nm due to strong phytoplankton absorption within 400 ~ 500 nm domain from the subsurface bloom layer. Moreover, high phytoplankton absorption coefficient was observed at the shorter wavelength (< 400nm). This strong absorption might be due to mycosporine-like amino acids, which absorb the UV (Kahru and Mitchell, 1998). And this subsurface C. polykrikoides bloom was detected by using dinoflagellate bloom detection algorithm, which is a simpler new satellite remote sensing-based harmful algal blooms detection method for JAXA's GCOM-C/SGLI (Siswanto et al., 2013). However, detection of the dinoflagellate Karenia mikimotoi bloom by using the algorithm on August 2013 was difficult as colored dissolved organic matter and detritus absorptions were high. Although the algorithm could detect the early stage of C. polycrikoides bloom, the algorithm improvement to detect the harmful algal blooms in the case II

  6. Escape of Pluto's Atmosphere: In Situ Measurements from New Horizons and Remote Observations from Chandra

    NASA Astrophysics Data System (ADS)

    McNutt, R. L., Jr.; Hill, M. E.; Kollmann, P.; Krimigis, S. M.; Brown, L. E.; Kusterer, M. B.; Lisse, C. M.; Mitchell, D. G.; Vandegriff, J. D.; McComas, D. J.; Bagenal, F.; Elliott, H. A.; Ennico Smith, K.; Horanyi, M.; Olkin, C.; Piquette, M. R.; Stern, A.; Strobel, D. F.; Szalay, J.; Valek, P. W.; Weaver, H. A., Jr.; Weidner, S.; Young, L. A.; Zirnstein, E.; Wolk, S. J.

    2015-12-01

    The escape rate of Pluto's atmosphere is of significant scientific interest. It is a Group 1 science goal of the New Horizons mission. In addition, a Group 3 science goal of the mission has been to characterize the energetic particle environment of the Pluto system. The Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) is a compact, energy by time-of-flight (TOF) instrument developed to address both of these science goals. Pluto is known to have an atmosphere, and current models postulate a majority N2 composition with free escape of up to ~1028 molecules/sec. This is very similar to the physical situation of a variety comets observed in the inner heliosphere. However, the gravitational field of Pluto exerts a significant effect on the escaping neutrals, unlike at a comet. The ionization of neutrals emitted from comets results in heavy ions, which are accelerated by the convective solar-wind electric field. The expected major ionization product near Pluto is singly ionized N2 molecules with pickup energies sufficient to be measured with PEPSSI. In the process of measuring the local energetic particle environment, such measurements will also provide constraints on the local density of Pluto's extended atmosphere, which, along with plasma measurements from the Solar Wind Around Pluto (SWAP) instrument also on New Horizons should allow the inference of the strengh and extent of mass-loading of the solar wind due to Pluto's atmosphere. Pluto's neutral atmosphere also provides a source population for charge exchange of highly ionized, minor ions in the solar wind, such as O, C, and N. This process allows these ions to capture one electron and be left in an excited state. That state, in turn decays with the emission of a low-energy (100 eV to 1 keV) X-ray, which can be detected at Earth. Such observations have been made of comets since the X-ray emission discovery in 1996 and used to infer cometary outgassing rates. Similar observatins have been made

  7. In Situ Observation of Dark Current Emission in a High Gradient rf Photocathode Gun

    NASA Astrophysics Data System (ADS)

    Shao, Jiahang; Shi, Jiaru; Antipov, Sergey P.; Baryshev, Sergey V.; Chen, Huaibi; Conde, Manoel; Gai, Wei; Ha, Gwanghui; Jing, Chunguang; Wang, Faya; Wisniewski, Eric

    2016-08-01

    Undesirable electron field emission (also known as dark current) in high gradient rf photocathode guns deteriorates the quality of the photoemission current and limits the operational gradient. To improve the understanding of dark current emission, a high-resolution (˜100 μ m ) dark current imaging experiment has been performed in an L -band photocathode gun operating at ˜100 MV /m of surface gradient. Scattered strong emission areas with high current have been observed on the cathode. The field enhancement factor β of selected regions on the cathode has been measured. The postexaminations with scanning electron microscopy and white light interferometry reveal the origins of ˜75 % strong emission areas overlap with the spots where rf breakdown has occurred.

  8. In situ measurements and radar observations of a severe storm - Electricity, kinematics, and precipitation

    NASA Technical Reports Server (NTRS)

    Byrne, G. J.; Few, A. A.; Stewart, M. F.; Conrad, A. C.; Torczon, R. L.

    1987-01-01

    Electric field measurements made inside a multicell severe storm in Oklahoma in 1983 with a balloon-borne instrument are presented. The properties of the electric charge regions, such as altitude, thickness, and charge concentrations, are studied. These measurements are analzyed with meteorological measurements of temperature and humidity, and balloon tracking and radar observations. The relation between the electric charge structure and the precipitation and kinematic features of the storm is examined. The data reveal that the cell exhibits a bipolar charge structure with negative charge below positive charge. The average charge concentrations of the two regions are estimated as -1.2 and 0.15 nC/cu m, respectively; the upper positive charge is about 6 km in vertical extent, and the lower negative charge is less than 1 km in vertical extent.

  9. Ozone Pollution, Transport and Variability: Examples from Satellite and In-Situ Observations

    NASA Technical Reports Server (NTRS)

    Thompson, Anne

    2003-01-01

    Regional and intercontinental transport of ozone has been observed from satellite, aircraft and sounding data. Over the past several years, we have developed new tropospheric ozone retrieval techniques from the TOMS (Total Ozone Mapping Spectrometer) satellite instrument that are of sufficient resolution to follow pollution episodes. The modified-residual technique uses Level 2 total ozone and was used to follow the 1997 fires in the wake of the El-Nino-related fires in southeast Asia and the Indonesian maritime continent. The TOMS-direct method ('TDOT' = TOMS Direct Ozone in the Troposphere) is a newer algorithm that uses TOMS radiances directly to extract tropospheric ozone. Ozonesonde data that have been taken in campaigns (e.g. TRACE-P) and more consistently in the SHADOZ (Southern Hemisphere Additional Ozonesondes) project, reveal layers of pollution traceable with trajectories. Examples will be shown of long-range transport and recirculation over Africa during SAFARI-2000.

  10. In situ observation of step-edge in-plane growth of graphene in a STEM

    PubMed Central

    Liu, Zheng; Lin, Yung-Chang; Lu, Chun-Chieh; Yeh, Chao-Hui; Chiu, Po-Wen; Iijima, Sumio; Suenaga, Kazu

    2014-01-01

    It is extremely difficult to control the growth orientation of the graphene layer in comparison to Si or III–V semiconductors. Here we report a direct observation of graphene growth and domain boundary formation in a scanning transmission electron microscope, with residual hydrocarbon in the microscope chamber being used as the carbon source for in-plane graphene growth at the step-edge of bilayer graphene substrate. We show that the orientation of the growth is strongly influenced by the step-edge structure and areas grown from a reconstructed 5–7 edge are rotated by 30° with respect to the mother layer. Furthermore, single heteroatoms like Si may act as catalytic active sites for the step-edge growth. The findings provide an insight into the mechanism of graphene growth and defect reconstruction that can be used to tailor carbon nanostructures with desired properties. PMID:24887183

  11. In situ observation of shear zone microstructures and strain localization using a transparent rotary shear apparatus

    NASA Astrophysics Data System (ADS)

    Korkolis, Evangelos

    An important focus of Geophysics is why geologic faults experience multiple styles of failure, ranging from stable aseismic creep to unstable seismic slip. Previous studies suggest that microstructures within fault gouge, a granular layer of wear material, have a significant effect on macroscopic fault behavior. This thesis investigates the effects of particle angularity, particle size distribution, total displacement, slip rate, and fault wall roughness on microstructures and grain kinematics in simulated gouge assemblages using a transparent rotary shear apparatus. Gouge strength increases with particle angularity, as evidenced by rotation of force chains near the sliding interface. Variations in slip rate and fault wall roughness appear to have no effect on the