ERUPTIVE ACTIVITY AND GLACIER CHANGES AT POPOCATEPETL VOLCANO, MEXICO

  The aim of the present work is the study of the eruptive activity-glacier interaction and, the effects on glacier evolution over 1994-2001. The glacial regime, morphological changes and infuence of the eruptive processes were determined in order to establish the eruptive activity-glacier interaction. Mass balances were carried out by means of photogrammetric techniques in order to determine the infuence of eruptive activity on the glacial regime. DEM comparisons allowed establishing spatial and temporal changes of area and volume of the glacier. Morphological changes were determined by photointerpretation, so the data obtained by this procedure and the data derived from DTM comparison were correlated to eruptive activity. The mass balance, and morphological changes at Popocatépetl volcano over 1994-2001 suggest that the eruptive activity accelerated the glacial retreat and cause its fragmentation.   Keywords: Popocatépetl Volcano, volcano-ice interactions, digital photogrammetry, glacial retreat.  El presente trabajo, se centra en el estudio del impacto de la actividad eruptiva del volcán Popocatépetl en el área glaciar durante el período 1994-2001. Para determinar el efecto de la actividad eruptiva en el régimen glaciar, se realizaron balances de masa empleando técnicas fotogramétricas, mediante la generación de modelos digitales de elevación (MDE). La compa­ración de MDEs permitió establecer los cambios glaciares en términos de área y volumen tanto temporales como espaciales. Así mismo, los cambios morfológicos del área glaciar fueron determinados con base en la fotointerpretación, de manera que los datos obtenidos por este procedimiento y los obtenidos mediante la comparación de los MDE se relacionaron con la actividad eruptiva a lo largo del periodo de estudio, estableciendo así la relación entre los fenómenos volcánicos y los cambios glaciares. Los resultados estimados del balance de masa del área glaciar y los cambios morfológicos observados a lo largo de 1994-2001 en el volcán Popocatépetl, permiten establecer que la actividad eruptiva aceleró el proceso de retroceso glaciar que tenía lugar desde principios del siglo XX y que culminó con la fragmentación del área glaciar.   Palabras clave: volcán Popocatépetl, interacción actividad eruptiva-glaciares, fotogrametría digital, retroceso glaciar.     &nbsp

ERUPTIVE ACTIVITY AND GLACIER CHANGES AT POPOCATEPETL VOLCANO, MEXICO

  The aim of the present work is the study of the eruptive activity-glacier interaction and, the effects on glacier evolution over 1994-2001. The glacial regime, morphological changes and infuence of the eruptive processes were determined in order to establish the eruptive activity-glacier interaction. Mass balances were carried out by means of photogrammetric techniques in order to determine the infuence of eruptive activity on the glacial regime. DEM comparisons allowed establishing spatial and temporal changes of area and volume of the glacier. Morphological changes were determined by photointerpretation, so the data obtained by this procedure and the data derived from DTM comparison were correlated to eruptive activity. The mass balance, and morphological changes at Popocatépetl volcano over 1994-2001 suggest that the eruptive activity accelerated the glacial retreat and cause its fragmentation.   Keywords: Popocatépetl Volcano, volcano-ice interactions, digital photogrammetry, glacial retreat.  El presente trabajo, se centra en el estudio del impacto de la actividad eruptiva del volcán Popocatépetl en el área glaciar durante el período 1994-2001. Para determinar el efecto de la actividad eruptiva en el régimen glaciar, se realizaron balances de masa empleando técnicas fotogramétricas, mediante la generación de modelos digitales de elevación (MDE). La compa­ración de MDEs permitió establecer los cambios glaciares en términos de área y volumen tanto temporales como espaciales. Así mismo, los cambios morfológicos del área glaciar fueron determinados con base en la fotointerpretación, de manera que los datos obtenidos por este procedimiento y los obtenidos mediante la comparación de los MDE se relacionaron con la actividad eruptiva a lo largo del periodo de estudio, estableciendo así la relación entre los fenómenos volcánicos y los cambios glaciares. Los resultados estimados del balance de masa del área glaciar y los cambios morfológicos observados a lo largo de 1994-2001 en el volcán Popocatépetl, permiten establecer que la actividad eruptiva aceleró el proceso de retroceso glaciar que tenía lugar desde principios del siglo XX y que culminó con la fragmentación del área glaciar.   Palabras clave: volcán Popocatépetl, interacción actividad eruptiva-glaciares, fotogrametría digital, retroceso glaciar.     &nbsp

Early in-flight detection of SO₂ via Differential Optical Absorption Spectroscopy: a feasible aviation safety measure to prevent potential encounters with volcanic plumes

Volcanic ash constitutes a risk to aviation, mainly due to its ability to cause jet engines to fail. Other risks include the possibility of abrasion of windshields and potentially serious damage to avionic systems. These hazards have been widely recognized since the early 1980s, when volcanic ash provoked several incidents of engine failure in commercial aircraft. In addition to volcanic ash, volcanic gases also pose a threat. Prolonged and/or cumulative exposure to sulphur dioxide (SO₂) or sulphuric acid (H₂SO₄) aerosols potentially affects e.g. windows, air frame and may cause permanent damage to engines. SO₂ receives most attention among the gas species commonly found in volcanic plumes because its presence above the lower troposphere is a clear proxy for a volcanic cloud and indicates that fine ash could also be present. <br><br> Up to now, remote sensing of SO₂ via Differential Optical Absorption Spectroscopy (DOAS) in the ultraviolet spectral region has been used to measure volcanic clouds from ground based, airborne and satellite platforms. Attention has been given to volcanic emission strength, chemistry inside volcanic clouds and measurement procedures were adapted accordingly. Here we present a set of experimental and model results, highlighting the feasibility of DOAS to be used as an airborne early detection system of SO₂ in two spatial dimensions. In order to prove our new concept, simultaneous airborne and ground-based measurements of the plume of Popocatépetl volcano, Mexico, were conducted in April 2010. The plume extended at an altitude around 5250 m above sea level and was approached and traversed at the same altitude with several forward looking DOAS systems aboard an airplane. These DOAS systems measured SO₂ in the flight direction and at &pm;40 mrad (2.3&deg;) angles relative to it in both, horizontal and vertical directions. The approaches started at up to 25 km distance to the plume and SO₂ was measured at all times well above the detection limit. In combination with radiative transfer studies, this study indicates that an extended volcanic cloud with a concentration of 10¹² molecules cm^&minus;3 at typical flight levels of 10 km can be detected unambiguously at distances of up to 80 km away. This range provides enough time (approx. 5 min) for pilots to take action to avoid entering a volcanic cloud in the flight path, suggesting that this technique can be used as an effective aid to prevent dangerous aircraft encounters with potentially ash rich volcanic clouds

Functional upgrading in China’s export processing sector

Functional upgrading occurs when a firm acquires more sophisticated functions within an existing value chain. In this paper, we analyze if there is evidence of this type of upgrading in China’s export processing regime by investigating dynamics in the relative prevalence of Import & Assembly (IA) versus Pure Assembly (PA) processing trade over the period 2000-2013. Firms in both regimes provide similar manufacturing services to foreign companies, but IA firms also conduct the sophisticated tasks of quality control, searching, financing and storing imported materials. Consistent with a trend of functional upgrading, we show that the share of IA trade in total processing trade has increased rapidly during the period 2000-2006, both overall and within product categories. Furthermore, we find that this trend has gone hand in hand with improvements in a sector’s labor productivity and unit values. Against expectations, we find that this process has slowed down notably during the period 2006-2013.status: publishe

Synoptic analysis of a decade of daily measurements of SO2 emission in the troposphere from volcanoes of the global ground-based Network for Observation of Volcanic and Atmospheric Change

Volcanic plumes are common and far-reaching manifestations of volcanic activity during and between eruptions. Observations of the rate of emission and composition of volcanic plumes are essential to recognize and, in some cases, predict the state of volcanic activity. Measurements of the size and location of the plumes are important to assess the impact of the emission from sporadic or localized events to persistent or widespread processes of climatic and environmental importance. These observations provide information on volatile budgets on Earth, chemical evolution of magmas, and atmospheric circulation and dynamics. Space-based observations during the last decades have given us a global view of Earth's volcanic emission, particularly of sulfur dioxide (SO2). Although none of the satellite missions were intended to be used for measurement of volcanic gas emission, specially adapted algorithms have produced time-averaged global emission budgets. These have confirmed that tropospheric plumes, produced from persistent degassing of weak sources, dominate the total emission of volcanic SO2. Although space-based observations have provided this global insight into some aspects of Earth's volcanism, it still has important limitations. The magnitude and short-term variability of lower-atmosphere emissions, historically less accessible from space, remain largely uncertain. Operational monitoring of volcanic plumes, at scales relevant for adequate surveillance, has been facilitated through the use of ground-based scanning differential optical absorption spectrometer (ScanDOAS) instruments since the beginning of this century, largely due to the coordinated effort of the Network for Observation of Volcanic and Atmospheric Change (NOVAC). In this study, we present a compilation of results of homogenized post-analysis of measurements of SO2 flux and plume parameters obtained during the period March 2005 to January 2017 of 32 volcanoes in NOVAC. This inventory opens a window into the short-term emission patterns of a diverse set of volcanoes in terms of magma composition, geographical location, magnitude of emission, and style of eruptive activity. We find that passive volcanic degassing is by no means a stationary process in time and that large sub-daily variability is observed in the flux of volcanic gases, which has implications for emission budgets produced using short-term, sporadic observations. The use of a standard evaluation method allows for intercomparison between different volcanoes and between ground- and space-based measurements of the same volcanoes. The emission of several weakly degassing volcanoes, undetected by satellites, is presented for the first time. We also compare our results with those reported in the literature, providing ranges of variability in emission not accessible in the past. The open-access data repository introduced in this article will enable further exploitation of this unique dataset, with a focus on volcanological research, risk assessment, satellite-sensor validation, and improved quantification of the prevalent tropospheric component of global volcanic emission

Improved functionalization of oleic acid-coated iron oxide nanoparticles for biomedical applications

Superparamagnetic iron oxide nanoparticles can providemultiple benefits for biomedical applications in aqueous environments such asmagnetic separation or magnetic resonance imaging. To increase the colloidal stability and allow subsequent reactions, the introduction of hydrophilic functional groups onto the particles’ surface is essential. During this process, the original coating is exchanged by preferably covalently bonded ligands such as trialkoxysilanes. The duration of the silane exchange reaction, which commonly takes more than 24 h, is an important drawback for this approach. In this paper, we present a novel method, which introduces ultrasonication as an energy source to dramatically accelerate this process, resulting in high-quality waterdispersible nanoparticles around 10 nmin size. To prove the generic character, different functional groups were introduced on the surface including polyethylene glycol chains, carboxylic acid, amine, and thiol groups. Their colloidal stability in various aqueous buffer solutions as well as human plasma and serum was investigated to allow implementation in biomedical and sensing applications.status: publishe

Low exposure long-baseline neutrino oscillation sensitivity of the DUNE experiment

The Deep Underground Neutrino Experiment (DUNE) will produce world-leading neutrino oscillation measurements over the lifetime of the experiment. In this work, we explore DUNE's sensitivity to observe charge-parity violation (CPV) in the neutrino sector, and to resolve the mass ordering, for exposures of up to 100 kiloton-megawatt-years (kt-MW-yr). The analysis includes detailed uncertainties on the flux prediction, the neutrino interaction model, and detector effects. We demonstrate that DUNE will be able to unambiguously resolve the neutrino mass ordering at a 3$\sigma$ (5$\sigma$) level, with a 66 (100) kt-MW-yr far detector exposure, and has the ability to make strong statements at significantly shorter exposures depending on the true value of other oscillation parameters. We also show that DUNE has the potential to make a robust measurement of CPV at a 3$\sigma$ level with a 100 kt-MW-yr exposure for the maximally CP-violating values \delta_{\rm CP}} = \pm\pi/2. Additionally, the dependence of DUNE's sensitivity on the exposure taken in neutrino-enhanced and antineutrino-enhanced running is discussed. An equal fraction of exposure taken in each beam mode is found to be close to optimal when considered over the entire space of interest

Long-baseline neutrino oscillation physics potential of the DUNE experiment

The sensitivity of the Deep Underground Neutrino Experiment (DUNE) to neutrino oscillation is determined, based on a full simulation, reconstruction, and event selection of the far detector and a full simulation and parameterized analysis of the near detector. Detailed uncertainties due to the flux prediction, neutrino interaction model, and detector effects are included. DUNE will resolve the neutrino mass ordering to a precision of 5σ, for all δ_(CP) values, after 2 years of running with the nominal detector design and beam configuration. It has the potential to observe charge-parity violation in the neutrino sector to a precision of 3σ (5σ) after an exposure of 5 (10) years, for 50% of all δ_(CP) values. It will also make precise measurements of other parameters governing long-baseline neutrino oscillation, and after an exposure of 15 years will achieve a similar sensitivity to sin²θ₁₃ to current reactor experiments