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1. Solar Orbiter's first Venus flyby: Observations from the Radio and Plasma Wave instrument

Author

Hadid, L. Z. Edberg, N. J. T. Chust, T. Pisa, D. and Dimmock, A. P. Morooka, M. W. Maksimovic, M. Khotyaintsev, V, Yu Soucek, J. Kretzschmar, M. Vecchio, A. Le Contel, O. Retino, A. Allen, R. C. Volwerk, M. Fowler, C. M. and Sorriso-Valvo, L. Karlsson, T. Santolik, O. Kolmasova, I and Sahraoui, F. Stergiopoulou, K. Moussas, X. Issautier, K. and Dewey, R. M. Wolt, M. Klein Malandraki, O. E. Kontar, E. P. and Howes, G. G. Bale, S. D. Horbury, T. S. Martinovic, M. and Vaivads, A. Krasnoselskikh, V Lorfevre, E. Plettemeier, D. Steller, M. Stverak, S. Travnicek, P. O'Brien, H. and Evans, V Angelini, V Velli, M. C. Zouganelis, I

Subjects
Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics
Abstract

Context. On December 27, 2020, Solar Orbiter completed its first gravity assist manoeuvre of Venus (VGAM1). While this flyby was performed to provide the spacecraft with sufficient velocity to get closer to the Sun and observe its poles from progressively higher inclinations, the Radio and Plasma Wave (RPW) consortium, along with other operational in situ instruments, had the opportunity to perform high cadence measurements and study the plasma properties in the induced magnetosphere of Venus. Aims. In this paper, we review the main observations of the RPW instrument during VGAM1. They include the identification of a number of magnetospheric plasma wave modes, measurements of the electron number densities computed using the quasi-thermal noise spectroscopy technique and inferred from the probe-to-spacecraft potential, the observation of dust impact signatures, kinetic solitary structures, and localized structures at the bow shock, in addition to the validation of the wave normal analysis on-board from the Low Frequency Receiver. Methods. We used the data products provided by the different subsystems of RPW to study Venus' induced magnetosphere. Results. The results include the observations of various electromagnetic and electrostatic wave modes in the induced magnetosphere of Venus: strong emissions of similar to 100 Hz whistler waves are observed in addition to electrostatic ion acoustic waves, solitary structures and Langmuir waves in the magnetosheath of Venus. Moreover, based on the different levels of the wave amplitudes and the large-scale variations of the electron number densities, we could identify different regions and boundary layers at Venus. Conclusions. The RPW instrument provided unprecedented AC magnetic and electric field measurements in Venus' induced magnetosphere for continuous frequency ranges and with high time resolution. These data allow for the conclusive identification of various plasma waves at higher frequencies than previously observed and a detailed investigation regarding the structure of the induced magnetosphere of Venus. Furthermore, noting that prior studies were mainly focused on the magnetosheath region and could only reach 10-12 Venus radii (R-V) down the tail, the particular orbit geometry of Solar Orbiter's VGAM1, allowed the first investigation of the nature of the plasma waves continuously from the bow shock to the magnetosheath, extending to similar to 70R(V) in the far distant tail region.

Published
2021

2. First observations and performance of the RPW instrument on board the Solar Orbiter mission

Author

M. Maksimovic, J. Souček, T. Chust, Y. Khotyaintsev, M. Kretzschmar, X. Bonnin, A. Vecchio, O. Alexandrova, S. D. Bale, D. Bérard, J.-Y. Brochot, N. J. T. Edberg, A. Eriksson, L. Z. Hadid, E. P. G. Johansson, T. Karlsson, B. Katra, V. Krasnoselskikh, V. Krupař, S. Lion, E. Lorfèvre, L. Matteini, Q. N. Nguyen, D. Píša, R. Piberne, D. Plettemeier, H. O. Rucker, O. Santolík, K. Steinvall, M. Steller, Š. Štverák, P. Trávníček, A. Vaivads, A. Zaslavsky, S. Chaintreuil, M. Dekkali, P.-A. Astier, G. Barbary, K. Boughedada, B. Cecconi, F. Chapron, C. Collin, D. Dias, L. Guéguen, L. Lamy, V. Leray, L. R. Malac-Allain, F. Pantellini, J. Parisot, P. Plasson, S. Thijs, I. Fratter, E. Bellouard, P. Danto, S. Julien, E. Guilhem, C. Fiachetti, J. Sanisidro, C. Laffaye, F. Gonzalez, B. Pontet, N. Quéruel, G. Jannet, P. Fergeau, T. Dudok de Wit, T. Vincent, C. Agrapart, J. Pragout, M. Bergerard-Timofeeva, G. T. Delory, P. Turin, A. Jeandet, P. Leroy, J.-C. Pellion, V. Bouzid, W. Recart, I. Kolmašová, O. Krupařová, L. Uhlíř, R. Lán, J. Baše, M. André, L. Bylander, V. Cripps, C. Cully, S.-E. Jansson, W. Puccio, J. Břínek, H. Ottacher, V. Angelini, M. Berthomier, V. Evans, K. Goetz, P. Hellinger, T. S. Horbury, K. Issautier, E. Kontar, O. Le Contel, P. Louarn, M. Martinović, D. Müller, H. O’Brien, C. J. Owen, A. Retino, J. Rodríguez-Pacheco, F. Sahraoui, L. Sanchez, A. P. Walsh, R. F. Wimmer-Schweingruber, I. Zouganelis, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire de Physique des Plasmas (LPP), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Swedish Institute of Space Physics [Uppsala] (IRF), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Centre National d'Études Spatiales [Toulouse] (CNES), Innovations for High Performance Microelectronics (IHP), Institut für Weltraumforschung = Space Research institute [Graz] (IWF), Osterreichische Akademie der Wissenschaften (ÖAW), Centre Hospitalier Régional Universitaire de Tours (CHRU Tours), Laboratoire de Biométrie et Biologie Evolutive - UMR 5558 (LBBE), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Recherche en Informatique et en Automatique (Inria)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS)-Centre National de la Recherche Scientifique (CNRS), Centre Hospitalier Lyon Sud [CHU - HCL] (CHLS), Hospices Civils de Lyon (HCL), ALTRAN (FRANCE), GeNeuro Innovation [Lyon], Hôpital Saint Eloi (CHRU Montpellier), Centre Hospitalier Régional Universitaire [Montpellier] (CHRU Montpellier), Institut des Neurosciences de Montpellier (INM), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Montpellier (UM), Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR), Nexeya Conseil & Formation, Institute of Atmospheric Physics [Prague] (IAP), Czech Academy of Sciences [Prague] (CAS), Microbes, Intestin, Inflammation et Susceptibilité de l'Hôte (M2iSH), Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre de Recherche en Nutrition Humaine d'Auvergne (CRNH d'Auvergne)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Clermont Auvergne (UCA), Service de Médecine Interne [CHU Clermont-Ferrand], CHU Gabriel Montpied [Clermont-Ferrand], CHU Clermont-Ferrand-CHU Clermont-Ferrand, Royal Institute of Technology [Stockholm] (KTH ), Department of Physics and Astronomy [Calgary], University of Calgary, Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), NOAA National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), National Institute of Water and Atmospheric Research [Wellington] (NIWA), Department of Physics [Imperial College London], Imperial College London, Université Paris sciences et lettres (PSL), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, University of Belgrade [Belgrade], Laboratoire des sciences de l'ingénieur, de l'informatique et de l'imagerie (ICube), École Nationale du Génie de l'Eau et de l'Environnement de Strasbourg (ENGEES)-Université de Strasbourg (UNISTRA)-Institut National des Sciences Appliquées - Strasbourg (INSA Strasbourg), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National de Recherche en Informatique et en Automatique (Inria)-Les Hôpitaux Universitaires de Strasbourg (HUS)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et Nanosciences Grand-Est (MNGE), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Sorbonne Université (SU), International Centre for Radio Astronomy Research - Curtin University, Curtin University [Perth], Planning and Transport Research Centre (PATREC)-Planning and Transport Research Centre (PATREC), European Space Astronomy Centre (ESAC), Agence Spatiale Européenne = European Space Agency (ESA), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), University of California [Berkeley], University of California-University of California, Institut für Weltraumforschung [Graz] (IWF), CHU Saint-Eloi, Institut des Neurosciences de Montpellier - Déficits sensoriels et moteurs (INM), Université de Montpellier (UM)-Institut National de la Santé et de la Recherche Médicale (INSERM), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées - Strasbourg (INSA Strasbourg), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-École Nationale du Génie de l'Eau et de l'Environnement de Strasbourg (ENGEES)-Réseau nanophotonique et optique, Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Matériaux et nanosciences d'Alsace (FMNGE), Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), European Space Agency (ESA), and Centre Hospitalier Régional Universitaire de Tours (CHRU TOURS)

Subjects
Sun: general, 010504 meteorology & atmospheric sciences, Astronomy, Astrophysics, 01 natural sciences, 7. Clean energy, law.invention, Orbiter, Astronomi, astrofysik och kosmologi, law, 0103 physical sciences, Astronomy, Astrophysics and Cosmology, Aerospace engineering, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, Sun: radio radiation, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Sun, Astronomy and Astrophysics, solar wind, Space and Planetary Science, general, radio radiation, Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience; The Radio and Plasma Waves (RPW) instrument on the ESA Solar Orbiter mission is designed to measure in situ magnetic and electric fields and waves from the continuum up to several hundred kHz. The RPW also observes solar and heliospheric radio emissions up to 16 MHz. It was switched on and its antennae were successfully deployed two days after the launch of Solar Orbiter on February 10, 2020. Since then, the instrument has acquired enough data to make it possible to assess its performance and the electromagnetic disturbances it experiences. In this article, we assess its scientific performance and present the first RPW observations. In particular, we focus on a statistical analysis of the first observations of interplanetary dust by the instrument’s Thermal Noise Receiver. We also review the electro-magnetic disturbances that RPW suffers, especially those which potential users of the instrument data should be aware of before starting their research work.

Published
2021
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3. Simulations of radio-wave anisotropic scattering to interpret type III radio bursts measurements by Solar Orbiter, Parker Solar Probe, STEREO and Wind

Author

S. Musset, M. Maksimovic, E. Kontar, V. Krupar, N. Chrysaphi, X. Bonnin, A. Vecchio, B. Cecconi, A. Zaslavsky, K. Issautier, S. D. Bale, M. Pulupa, Issautier, Karine, Observatoire de Paris, Université Paris sciences et lettres (PSL), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astronomy, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Space Physics (physics.space-ph), Astrophysics - Solar and Stellar Astrophysics, Physics - Space Physics, Space and Planetary Science, 0103 physical sciences, [SDU.ASTR.SR] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences
Abstract

Aims. We use multi-spacecraft observations of individual type III radio bursts to calculate the directivity of the radio emission. We compare these data to the results of ray-tracing simulations of the radio-wave propagation and probe the plasma properties of the inner heliosphere. Methods. We used ray-tracing simulations of radio-wave propagation with anisotropic scattering on density inhomogeneities to study the directivity of radio emissions. Simultaneous observations of type III radio bursts by four widely separated spacecraft were used to calculate the directivity and position of the radio sources. The shape of the directivity pattern deduced for individual events is compared to the directivity pattern resulting from the ray-tracing simulations. Results. We show that simultaneous observations of type radio III bursts by four different probes provide an opportunity to estimate the radio source positions and the directivity of the radio emission. The shape of the directivity varies from one event to another and it is consistent with anisotropic scattering of the radio waves.

Published
2021

4. Long-term sustained observing system for climatic variability studies in the Mediterranean

Author

Alexander Theocharis, null CIESM initiative group, A. Abdul Fattah, M. Astraldi, R. Boscolo, H. Bryden, G. Civitarese, J. Font, M. Gacic, G.P. Gasparini, D. Georgopoulos, I. Gertman, J. Gould, D. Jourdan, B. Klein, E. Kontar, A. Lascaratos, J.L. Lopez-Jurado, C. Maillard, P. Malanotte-Rizzoli, B. Manca, G. Manzella, C. Millot, S. Papaevangelou, N. Pinardi, P. Povinec, L. Prieur, W. Roether, J. Salat, M. Snoussi, M. Tber, M. Triki, M. Vargas, and I. Vilibic

Subjects
Mediterranean climate, Monsoon of South Asia, Biogeochemical cycle, Oceanography, Climatology, Environmental science, Thermohaline circulation, Outflow, Climatic variability, Forcing (mathematics), Term (time)
Abstract

During the CIESM workshop (Monaco, 22–24 April 2002) entitled “Monitoring Hydro- logical Trends in the Mediterranean”, the review of existing data sets and analyses has revealed important variability in the dynamics and hydrological characteristics, in the past century, ranging from interannual to decadal time scales. These variations are related mainly to local forcing and larger scale atmospheric parameters (NAO, ENSO, Indian monsoon). Moreover, abrupt events contribute to modification of the Mediter- ranean conveyor belt, also influencing the biogeochemical environment and the Mediter- ranean outflow in the Atlantic Ocean. The participating scientists have agreed on the need of a sustained multi-component long-term monitoring system based on both oceanographic and atmospheric observations and modelling. The group also proposed an expansion and strengthening of the ongoing relevant large operational programs by a “climatic approach” component.

Published
2003
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5. Propagation of electron beam in inhomogeneous plasma

Author

V. Lapshin, V. Mel'nik, and E. Kontar

Subjects
Physics, Electron density, Physics::Plasma Physics, Physics::Space Physics, Cathode ray, Relaxation (physics), Plasma, Relaxation length, Electron, Atomic physics, Plasma oscillation, Corona
Abstract

Summary form only given. The propagation of electron beam generating solar type III bursts is considered at the distances much larger than the length of quasilinear relaxation. As it takes place in homogeneous plasma the electron beam being initially monoenergetic propagates as a beam-plasma structure that consists of electrons and Langmuir waves. Beam-plasma structure propagating in uniform plasma loses a part of the fastest and the slowest electrons that leads to its decay. The maximum of electron density and energy density of plasma waves propagates with constant velocity. The numerical simulations fulfilled show that the inhomogeneity with decreasing density at the scales larger than the relaxation length can increase the time of this structure existence in corona.

Published
2002
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6. Fragmentation of electron stream propagation through plasma

Author

E. Kontar and V. Mel'nik

Subjects
Physics, Plasma window, Two-stream instability, Physics::Plasma Physics, Waves in plasmas, Plasma parameters, Physics::Accelerator Physics, Plasma diagnostics, Electromagnetic electron wave, Electron, Atomic physics, Plasma oscillation
Abstract

Summary form only given, as follows. The propagation of an electron stream is considered in the limit of weak turbulence when the quasilinear time is much smaller than the time of electron stream flying-off. It is found out that the initial electron distribution function of the electron stream propagating in plasma is unstable to decay into separate beams. Langmuir waves excited by the fast beams accelerate electrons of slow beams that leads to interaction between them: the number of particles in the fast beams increases and their phases change. The electron distribution function and spectral energy density of plasma oscillation are found by gas-dynamic approximation.

Published
2002
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8. Electron Acceleration during Macroscale Magnetic Reconnection.

Author

Arnold H, Drake JF, Swisdak M, Guo F, Dahlin JT, Chen B, Fleishman G, Glesener L, Kontar E, Phan T, and Shen C

Abstract

The first self-consistent simulations of electron acceleration during magnetic reconnection in a macroscale system are presented. Consistent with solar flare observations, the spectra of energetic electrons take the form of power laws that extend more than two decades in energy. The drive mechanism for these nonthermal electrons is Fermi reflection in growing and merging magnetic flux ropes. A strong guide field suppresses the production of nonthermal electrons by weakening the Fermi drive mechanism. For a weak guide field the total energy content of nonthermal electrons dominates that of the hot thermal electrons even though their number density remains small. Our results are benchmarked with the hard x-ray, radio, and extreme ultraviolet observations of the X8.2-class solar flare on September 10, 2017.

Published
2021
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9. Isotopic, geophysical and biogeochemical investigation of submarine groundwater discharge: IAEA-UNESCO intercomparison exercise at Mauritius Island.

Author

Povinec PP, Burnett WC, Beck A, Bokuniewicz H, Charette M, Gonneea ME, Groening M, Ishitobi T, Kontar E, Liong Wee Kwong L, Marie DE, Moore WS, Oberdorfer JA, Peterson R, Ramessur R, Rapaglia J, Stieglitz T, and Top Z

Subjects
Mauritius, Radium analysis, Radon analysis, Tritium analysis, United Nations, Water Movements, Environmental Monitoring, Groundwater analysis, Radioisotopes analysis, Seawater analysis, Ships, Water Pollutants, Radioactive analysis
Abstract

Submarine groundwater discharge (SGD) into a shallow lagoon on the west coast of Mauritius Island (Flic-en-Flac) was investigated using radioactive ((3)H, (222)Rn, (223)Ra, (224)Ra, (226)Ra, (228)Ra) and stable ((2)H, (18)O) isotopes and nutrients. SGD intercomparison exercises were carried out to validate the various approaches used to measure SGD including radium and radon measurements, seepage rate measurements using manual and automated meters, sediment bulk conductivity and salinity surveys. SGD measurements using benthic chambers placed on the floor of the Flic-en-Flac Lagoon showed discharge rates up to 500 cm/day. Large variability in SGD was observed over distances of a few meters, which were attributed to different geomorphological features. Deployments of automated seepage meters captured the spatial and temporal variability of SGD with a mean seepage rate of 10 cm/day. The stable isotopic composition of submarine waters was characterized by significant variability and heavy isotope enrichment and was used to predict the contribution of fresh terrestrially derived groundwater to SGD (range from a few % to almost 100%). The integrated SGD flux, estimated from seepage meters placed parallel to the shoreline, was 35 m(3)/m day, which was in reasonable agreement with results obtained from a hydrologic water balance calculation (26 m(3)/m day). SGD calculated from the radon inventory method using in situ radon measurements were between 5 and 56 m(3)/m per day. Low concentrations of radium isotopes observed in the lagoon water reflected the low abundance of U and Th in the basalt that makes up the island. High SGD rates contribute to high nutrients loading to the lagoon, potentially leading to eutrophication. Each of the applied methods yielded unique information about the character and magnitude of SGD. The results of the intercomparison studies have resulted a better understanding of groundwater-seawater interactions in coastal regions. Such information is an important pre-requisite for the protection and management of coastal freshwater resources., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Published
2012
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10. Quantifying submarine groundwater discharge in the coastal zone via multiple methods.

Author

Burnett WC, Aggarwal PK, Aureli A, Bokuniewicz H, Cable JE, Charette MA, Kontar E, Krupa S, Kulkarni KM, Loveless A, Moore WS, Oberdorfer JA, Oliveira J, Ozyurt N, Povinec P, Privitera AM, Rajar R, Ramessur RT, Scholten J, Stieglitz T, Taniguchi M, and Turner JV

Subjects
Brazil, Ecology statistics & numerical data, Geography, Italy, Mauritius, New York, United Nations, Western Australia, Ecology methods, Environment, Fresh Water, Water Movements
Abstract

Submarine groundwater discharge (SGD) is now recognized as an important pathway between land and sea. As such, this flow may contribute to the biogeochemical and other marine budgets of near-shore waters. These discharges typically display significant spatial and temporal variability making assessments difficult. Groundwater seepage is patchy, diffuse, temporally variable, and may involve multiple aquifers. Thus, the measurement of its magnitude and associated chemical fluxes is a challenging enterprise. A joint project of UNESCO and the International Atomic Energy Agency (IAEA) has examined several methods of SGD assessment and carried out a series of five intercomparison experiments in different hydrogeologic environments (coastal plain, karst, glacial till, fractured crystalline rock, and volcanic terrains). This report reviews the scientific and management significance of SGD, measurement approaches, and the results of the intercomparison experiments. We conclude that while the process is essentially ubiquitous in coastal areas, the assessment of its magnitude at any one location is subject to enough variability that measurements should be made by a variety of techniques and over large enough spatial and temporal scales to capture the majority of these changing conditions. We feel that all the measurement techniques described here are valid although they each have their own advantages and disadvantages. It is recommended that multiple approaches be applied whenever possible. In addition, a continuing effort is required in order to capture long-period tidal fluctuations, storm effects, and seasonal variations.

Published
2006
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