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Radar observations of ship-induced instabilities in the ocean-atmosphere system ArchiMer
Smirnov, Av.
Both natural and artificial (ship-induced) features of atmospheric motions can be seen in ocean radar imagery. Observations of a surface wake extending downstream from the atmospheric vortices in a thermal ship plume are described. To demonstrate the usefulness of radar systems in observing the ocean surface, we studied the behavior of hot ship exhaust, using a 2.25-cm-wavelength airborne radar. The ship-induced feature in the polarimetric radar images was observed in the ocean surface cold environment with moderate horizontal ambient winds. The smoke-like feature appears only in the vertically-polarized images, and not in the horizontally-polarized images.
Tipo: Text Palavras-chave: Imagerie radar; Polarisation; Sillage d'un navire; Vorticité atmosphérique; Panache thermique; Radar images; Polarization; Ship track; Atmospheric vorticity; Thermal plume.
Ano: 1999 URL: http://archimer.ifremer.fr/doc/00325/43627/43256.pdf
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Planck 2018 results: XII. Galactic astrophysics using polarized dust emission ArchiMer
Aghanim, N.; Akrami, Y.; Alves, Mir; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Ballardini, M.; Banday, A. J.; Barreiro, R. B.; Bartolo, N.; Basak, S.; Benabed, K.; Bernard, J. -p.; Bersanelli, M.; Bielewicz, P.; Bock, J. J.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bracco, A.; Bucher, M.; Burigana, C.; Calabrese, E.; Cardoso, J. -f.; Carron, J.; Chary, R. -r.; Chiang, H. C.; Colombo, L. P. L.; Combet, C.; Crill, B. P.; Cuttaia, F.; De Bernardis, P.; De Zotti, G.; Delabrouille, J.; Delouis, Jean Marc; Di Valentino, E.; Dickinson, C.; Diego, J. M.; Dore, O.; Douspis, M.; Ducout, A.; Dupac, X.; Efstathiou, G.; Elsner, F.; Ensslin, T. A.; Eriksen, H. K.; Falgarone, E.; Fantaye, Y.; Fernandez-cobos, R.; Ferriere, K.; Finelli, F.; Forastieri, F.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Frolov, A.; Galeotta, S.; Galli, S.; Ganga, K.; Genova-santos, R. T.; Gerbino, M.; Ghosh, T.; Gonzalez-nuevo, J.; Gorski, K. M.; Gratton, S.; Green, G.; Gruppuso, A.; Gudmundsson, J. E.; Guillet, V.; Handley, W.; Hansen, F. K.; Helou, G.; Herranz, D.; Hivon, E.; Huang, Z.; Jaffe, A. H.; Jones, W. C.; Keihanen, E.; Keskitalo, R.; Kiiveri, K.; Kim, J.; Krachmalnicoff, N.; Kunz, M.; Kurki-suonio, H.; Lagache, G.; Lamarre, J. -m.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Le Jeune, M.; Levrier, F.; Liguori, M.; Lilje, P. B.; Lindholm, V.; Lopez-caniego, M.; Lubin, Pm; Ma, Y. -z.; Macias-perez, J. F.; Maggio, G.; Maino, D.; Mandolesi, N.; Mangilli, A.; Marcos-caballero, A.; Maris, M.; Martin, Pg; Martinez-gonzalez, E.; Matarrese, S.; Mauri, N.; Mcewen, J. D.; Melchiorri, A.; Mennella, A.; Migliaccio, M.; Miville-deschenes, M. -a.; Molinari, D.; Moneti, A.; Montier, L.; Morgante, G.; Moss, A.; Natoli, P.; Pagano, L.; Paoletti, D.; Patanchon, G.; Perrotta, F.; Pettorino, V.; Piacentini, F.; Polastri, L.; Polenta, G.; Puget, J. -l.; Rachen, J. P.; Reinecke, M.; Remazeilles, M.; Renzi, A.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rubino-martin, J. A.; Ruiz-granados, B.; Salvati, L.; Sandri, M.; Savelainen, M.; Scott, D.; Sirignano, C.; Sunyaev, R.; Suur-uski, A. -s.; Tauber, J. A.; Tavagnacco, D.; Tenti, M.; Toffolatti, L.; Tomasi, M.; Trombetti, T.; Valiviita, J.; Vansyngel, F.; Van Tent, B.; Vielva, P.; Villa, F.; Vittorio, N.; Wandelt, B. D.; Wehus, I. K.; Zacchei, A.; Zonca, A..
Observations of the submillimetre emission from Galactic dust, in both total intensity I and polarization, have received tremendous interest thanks to the Planck full-sky maps. In this paper we make use of such full-sky maps of dust polarized emission produced from the third public release of Planck data. As the basis for expanding on astrophysical studies of the polarized thermal emission from Galactic dust, we present full-sky maps of the dust polarization fraction p, polarization angle psi, and dispersion function of polarization angles ?. The joint distribution (one-point statistics) of p and N-H confirms that the mean and maximum polarization fractions decrease with increasing N-H. The uncertainty on the maximum observed polarization fraction, (max) =...
Tipo: Text Palavras-chave: Polarization; Magnetic fields; Turbulence; Dust; Extinction; Local insterstellar matter; Submillimeter: ISM.
Ano: 2020 URL: https://archimer.ifremer.fr/doc/00654/76632/77786.pdf
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Polarized Earth's ambient microseismic noise ArchiMer
Schimmel, M.; Stutzmann, E.; Ardhuin, Fabrice; Gallart, J..
We quantify, analyze, and characterize the frequency-dependent microseismic noise recorded by worldwide distributed seismic stations. Microseismic noise is generated through the interaction of ocean waves. It is the strongest ambient noise, and it is observed everywhere on Earth. We introduce a new approach which permits us to detect polarized signals in the time-frequency domain and which we use to characterize the microseismic noise. We analyze 7 years of continuous seismograms from the global GEOSCOPE network. Microseisms are dominated by Rayleigh waves, and we therefore focus on elliptically polarized signals. The polarized signals are detected in the time-frequency domain through a degree of polarization measure. We design polarization spectra and...
Tipo: Text Palavras-chave: Microseismic noise; Polarization; Primary and secondary microseisms; Seismology.
Ano: 2011 URL: http://archimer.ifremer.fr/doc/00041/15219/12713.pdf
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Sea-ice detection for autonomous underwater vehicles and oceanographic lagrangian platforms by continuous-wave laser polarimetry ArchiMer
Lagunas, Jose; Marec, Claudie; Leymarie, Edouard; Penkerc'H, Christophe; Rehm, Eric; Desaulniers, Pierre; Brousseau, Denis; Larochelle, Patrick; Roy, Gilles; Fournier, Georges; Thibault, Simon; Babin, Marcel.
The use of Lagrangian platforms and of Autonomous Underwater Vehicles (AUVs) in oceanography has increased rapidly over the last decade along with the development of improved biological and chemical sensors. These vehicles provide new spatial and temporal scales for observational studies of the ocean. They offer a broad range of deployment and recovery capabilities that reduce the need of large research vessels. This is especially true for ice-covered Arctic ocean where surface navigation is only possible during the summer period. Moreover, safe underwater navigation in icy waters requires the capability of detecting sea ice on the surface (ice sheets). AUVs navigating in such conditions risk collisions, RF communication shadowing, and being trapped by ice...
Tipo: Text Palavras-chave: Lidar; Polarization; Sea-ice; AUV; Argo; Arctic; Amundsen; Marine robotics.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00475/58665/61166.pdf
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Combined wind vector and sea state impact on ocean nadir-viewing Ku- and C-band radar cross-sections ArchiMer
Tran, Ngan; Chapron, Bertrand.
The authors report the first results in studying the polarization anisotropy of the microwave backscatter from nadir observations provided by Jason-1 altimeter in both Ku- and C-band. A small but clear wind direction signal for wind speeds above 6 m/s is revealed. These azimuthal variations of radar cross-section increase with increasing wind speed up to 14 m/s. The signatures then level off at higher winds. These results extend, for the first time, recent theoretical improved scattering approximation, and point some similarities between scattering and emission mechanisms at nadir. The observed directional effect can thus be interpreted as a signature of the curvature anisotropy of wind-generated short-scale waves. Sensitivities to both wind speed and sea...
Tipo: Text Palavras-chave: Altimeter; Radar cross section; Polarization; Wind direction; Sea state.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/00004/11557/8150.pdf
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Frequency-dependent noise sources in the North Atlantic Ocean ArchiMer
Sergeant, Amandine; Stutzmann, Eleonore; Maggi, Alessia; Schimmel, Martin; Ardhuin, Fabrice; Obrebski, Mathias.
[1] Secondary microseisms are the most energetic waves in the noise spectra between 3 and 10 s. They are generated by ocean wave interactions and are predominantly Rayleigh waves. We study the associated noise sources in the North Atlantic Ocean by coupling noise polarization analysis and source mapping using an ocean wave model that takes into account coastal reflections. From the Rayleigh wave polarization analysis, we retrieve the back azimuth to the noise sources in the time-frequency domain. Noise source modeling enables us to locate the associated generation areas at different times and frequencies. We analyze the distribution of secondary microseism sources in the North Atlantic Ocean using 20 broadband stations located in the Arctic and around the...
Tipo: Text Palavras-chave: Noise sources; Secondary microseism; North Atlantic Ocean; Polarization.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00169/28075/26290.pdf
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Gauging the potential for social unrest AgEcon
Stark, Oded; Hyll, Walter; Behrens, Doris A..
It stands to reason that social unrest does not erupt out of the blue. Although there are a great many reasons why social dismay might descend into social disorder, only few yardsticks or indices can plausibly be used to gauge the potential for social unrest (PSU). If policy makers want to undertake public action to prevent social dismay escalating into social disruption, they obviously need to draw on practical sensors. This paper assesses critically the adequacy of two such measures, the polarization (P) index, and the total relative deprivation (TRD) index. The paper proposes a tentative guide to selecting between these two measures. A review of three stylized scenarios suggests that, where income redistributions reduce the number of distinct income...
Tipo: Working or Discussion Paper Palavras-chave: Social dismay; The potential for social unrest; Polarization; Total relative deprivation; Policy choice; Public Economics; D31; D63.
Ano: 2009 URL: http://purl.umn.edu/53721
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