Network for Observation of Volcanic and Atmospheric Change (NOVAC)—A global network for volcanic gas monitoring: Network layout and instrument description

This paper presents the global project Network for Observation of Volcanic and Atmospheric Change (NOVAC), the aim of which is automatic gas emission monitoring at active volcanoes worldwide. Data from the network will be used primarily for volcanic risk assessment but also for geophysical research, studies of atmospheric change, and ground validation of satellite instruments. A novel type of instrument, the scanning miniaturized differential optical absorption spectroscopy (Mini-DOAS) instrument, is applied in the network to measure volcanic gas emissions by UV absorption spectroscopy. The instrument is set up 5-10 km downwind of the volcano under study, and typically two to four instruments are deployed at each volcano in order to cover different wind directions and to facilitate measurements of plume height and plume direction. Two different versions of the instrument have been developed. Version I was designed to be a robust and simple instrument for measurement of volcanic SO2 emissions at high time resolution with minimal power consumption. Version II was designed to allow the best possible spectroscopy and enhanced flexibility in regard to measurement geometry at the cost of larger complexity, power consumption, and price. In this paper the project is described, as well as the developed software, the hardware of the two instrument versions, measurement strategies, data communication, and archiving routines. As of April 2009 a total of 46 instruments have been installed at 18 volcanoes worldwide. As a typical example, the installation at Tungurahua volcano in Ecuador is described, together with some results from the first 21 months of operation at this volcano.

[1]  John P. Burrows,et al.  MAX-DOAS measurements of formaldehyde in the Po-Valley , 2004 .

[2]  Mike Burton,et al.  Three-years of SO2 flux measurements of Mt. Etna using an automated UV scanner array: Comparison with conventional traverses and uncertainties in flux retrieval , 2009 .

[3]  P. Xie,et al.  Observations of carbon disulfide by differential optical absorption spectroscopy in Shanghai , 2004 .

[4]  Clive Oppenheimer,et al.  Plume velocity determination for volcanic SO2 flux measurements , 2005 .

[5]  A. Vandaele,et al.  SO2 Absorption Cross-section Measurement in the UV using a Fourier Transform Spectrometer , 1994 .

[6]  O. Edenhofer,et al.  Mitigation from a cross-sectoral perspective , 2007 .

[7]  A. Robock.  The Climatic Aftermath , 2002, Science.

[8]  Hugo Yepes,et al.  Degassing patterns of Tungurahua volcano (Ecuador) during the 1999–2006 eruptive period, inferred from remote spectroscopic measurements of SO2 emissions , 2008 .

[9]  Christoph Kern,et al.  Spectroscopic measurements of volcanic gas emissions in the ultra-violet wavelength region , 2009 .

[10]  Hans-F. Graf,et al.  The annual volcanic gas input into the atmosphere, in particular into the stratosphere: a global data set for the past 100 years , 2002 .

[11]  Raymond M. Hoff,et al.  Differential SO2 Column Measurements of the Mt. Pinatubo Volcanic Plume , 1992, Optical Remote Sensing of the Atmosphere.

[12]  M M Millan,et al.  The applications of optical correlation techniques to the remote sensing of SO 2 plumes using sky light. , 1971, Atmospheric environment.

[13]  Shin Yoshikawa,et al.  Effect of UV scattering on SO2 emission rate measurements , 2006 .

[14]  Keith A. Horton,et al.  Accurately measuring volcanic plume velocity with multiple UV spectrometers , 2006 .

[15]  I. Pundt,et al.  2-D reconstruction of atmospheric concentration peaks from horizontal long path DOAS tomographic measurements: parametrisation and geometry within a discrete approach , 2005 .

[16]  P. Baxter,et al.  Atmospheric dispersion, environmental effects and potential health hazard associated with the low-altitude gas plume of Masaya volcano, Nicaragua , 2002 .

[17]  Jp Davis,et al.  Bifurcation of volcanic plumes in a crosswind , 1994 .

[18]  R. Hoff,et al.  Remote SO2 Mass Flux Measurements Using COSPEC , 1981 .

[19]  A. Robock.  Pinatubo eruption. The climatic aftermath. , 2002, Science.

[20]  U. Platt,et al.  Halogen oxide measurements at Masaya Volcano, Nicaragua using active long path differential optical absorption spectroscopy , 2009 .

[21]  Ulrich Platt,et al.  Observations of BrO and its vertical distribution during surface ozone depletion at Alert , 2002 .

[22]  U. Platt,et al.  Detection of bromine monoxide in a volcanic plume , 2003, Nature.

[23]  U. Platt,et al.  Numerical analysis and estimation of the statistical error of differential optical absorption spectroscopy measurements with least-squares methods. , 1996, Applied optics.

[24]  Toshiya Mori,et al.  Computed tomography reconstruction of SO2 concentration distribution in the volcanic plume of Miyakejima, Japan, by airborne traverse technique using three UV spectrometers , 2008 .

[25]  J. Noxon,et al.  Nitrogen Dioxide in the Stratosphere and Troposphere Measured by Ground-Based Absorption Spectroscopy , 1975, Science.

[26]  William I. Rose,et al.  Volcanic-gas studies: Methods, results, and applications , 1994 .

[27]  Ulrich Platt,et al.  MAX‐DOAS O4 measurements: A new technique to derive information on atmospheric aerosols—Principles and information content , 2004 .

[28]  Anomalous Emissions of SO2 During the Recent Eruption of Santa Ana Volcano, El Salvador, Central America , 2007 .

[29]  B. Galle,et al.  Tomographic reconstruction of gas plumes using scanning DOAS , 2009 .

[30]  Ulrich Platt,et al.  Correction of the oxygen interference with UV spectroscopic (DOAS) measurements of monocyclic aromatic hydrocarbons in the atmosphere , 1998 .

[31]  T. E. Wright,et al.  Scanning tomography of SO2 distribution in a volcanic gas plume , 2008 .

[32]  Ulrich Platt,et al.  MAX‐DOAS O4 measurements: A new technique to derive information on atmospheric aerosols: 2. Modeling studies , 2006 .

[33]  R. Sparks,et al.  Dynamics of magma degassing , 2003, Geological Society, London, Special Publications.

[34]  M. Millán,et al.  Remote sensing of air pollutants. A study of some atmospheric scattering effects , 1980 .

[35]  C. Oppenheimer,et al.  SO2 emissions from Soufrière Hills Volcano and their relationship to conduit permeability, hydrothermal interaction and degassing regime , 2003 .

[36]  Stanley C. Solomon,et al.  On the interpretation of zenith sky absorption measurements , 1987 .

[37]  Deliang Chen,et al.  The dual-beam mini-DOAS technique—measurements of volcanic gas emission, plume height and plume speed with a single instrument , 2009 .

[38]  A. McGonigle,et al.  A miniaturised ultraviolet spectrometer for remote sensing of SO2 fluxes: a new tool for volcano surveillance , 2003 .

[39]  Johannes Orphal,et al.  The temperature dependence (203-293 K) of the absorption cross sections of O3 in the 230-850 nm region measured by Fourier-transform spectroscopy , 2001 .

[40]  S. Solomon.  The Physical Science Basis : Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change , 2007 .

[41]  Clive Oppenheimer,et al.  Automated, high time-resolution measurements of SO2 flux at Soufrière Hills Volcano, Montserrat , 2003 .

[42]  J. Pennec,et al.  The AD 1300-1700 eruptive periods at Tungurahua volcano, Ecuador, revealed by historical narratives, stratigraphy and radiocarbon dating , 2008 .

[43]  Dietrich Althausen,et al.  Retrieval of Aerosol Profiles using Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) , 2003 .

[44]  Peter J. Baxter,et al.  Medical effects of volcanic eruptions , 1990 .

[45]  U. Platt,et al.  Simultaneous measurement of atmospheric CH2O, O3, and NO2 by differential optical absorption , 1979 .

[46]  Christoph Kern,et al.  Radiative transfer corrections for accurate spectroscopic measurements of volcanic gas emissions , 2010 .