http://hdl.handle.net/2122/84 Search the Channel search http://www.earth-prints.org/simple-search http://hdl.handle.net/2122/4150 Title: Strumentazioni in uso nel campo della petrologia sperimentale <br/> <br/>Authors: Misiti, V.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Iarocci, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia <br/> <br/>Abstract: This guide reports the description of the experimental apparata in use in the experimental petrology along with an accurate description of some applications of these instrumentations. After a brief introduction concerning what is the experimental petrology and what is used for, we provide a description of the starting materials used in this field of the Earth Sciences. Moreover, particular attention is focused on these apparata used all around the world. We, finally, introduce some examples of different studies conducted with the different experimental equipments. The aim of this guide is, then, to give information concerning the equipments and their potentiality. Mon, 29 Oct 2007 22:58:59 GMT http://hdl.handle.net/2122/4147 Title: Electrical conductivity of a phonotephrite from Mt. Vesuvius: the importance of chemical composition on the lectrical conductivity of silicate melts <br/> <br/>Authors: Poe, B. T.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Romano, C.; Università Roma Tre; Varchi, V.; Università Roma Tre; Misiti, V.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Scarlato, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia <br/> <br/>Abstract: The bulk electrical conductivity of the phonotephritic lava from the 1944 eruption of Mt Vesuvius was measured using complex impedance spectroscopy in a multianvil apparatus at 1 GPa and temperatures up to 700 °C. Melting experiments prior to the electrical measurements were also performed on this sample in a piston cylinder apparatus in order to gauge how bulk conductivity varies as a function of its melt fraction. Unlike the behaviour found in basaltic rocks in which conductivity increases with increasing melt fraction, we observe a conductivity decrease of the order of a factor of ten for samples at 700 °C ranging in melt fraction from 32 vol.% to completely molten.We attribute this anomalous behaviour to the progressive loss of highly conductive leucite upon melting. The addition of potassium to the melt phase, however, does not result in an increase of the total alkali concentration due to the melting of other mineral components. We also present an empirical model to predict the electrical conductivity of fully molten silicate liquids as a function of temperature and chemical composition, based on conductivity data for natural silicate liquids found in the literature. The inclusion of compositional terms reduces the error by more than a factor of four with respect to a composition independent, temperature-only parameterization. Thu, 29 May 2008 22:58:59 GMT http://hdl.handle.net/2122/4085 Title: Retrieval of foreign-broadened water vapor continuum coefficients from emitted spectral radiance in the H2O rotational band from 240 to 590 cm −1 <br/> <br/>Authors: Serio, C.; Dip. Ingegeneria e Fisica dell’Ambiente, Università della Basilicata, Potenza, Italy; Masiello, G.; Dip. Ingegeneria e Fisica dell’Ambiente, Università della Basilicata, Potenza, Italy; Esposito, F.; Dip. Ingegeneria e Fisica dell’Ambiente, Università della Basilicata, Potenza, Italy; Di Girolamo, P.; Dip. Ingegeneria e Fisica dell’Ambiente, Università della Basilicata, Potenza, Italy; Di Iorio, T.; Dip. Fisica, Università di Roma ”La Sapienza”, Roma, Italy; Palchetti, L.; Istituto di Fisica Applicata ”Nello Carrara”, IFAC-CNR, Firenze, Italy; Bianchini, G.; Istituto di Fisica Applicata ”Nello Carrara”, IFAC-CNR, Firenze, Italy; Muscari, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Pavese, G.; Istituto di Metodologie per l’Analisi Ambientale, IMAA-CNR, Potenza, Italy; Rizzi, R.; Dip. Fisica, Università di Bologna, Bologna, Italy; Carli, B.; Istituto di Fisica Applicata ”Nello Carrara”, IFAC-CNR, Firenze, Italy; Cuomo, V.; Istituto di Metodologie per l’Analisi Ambientale, IMAA-CNR, Potenza, Italy <br/> <br/>Abstract: The paper presents a novel methodology to retrieve the foreign-broadened water vapor continuum absorption coefficients in the spectral range 240 to 590 cm−1 and is the first estimation of the continuum coefficient at wave numbers smaller than 400 cm−1 under atmospheric conditions. The derivation has been accomplished by processing a suitable set of atmospheric emitted spectral radiance observations obtained during the March 2007 Alps campaign of the ECOWAR project (Earth COoling by WAter vapor Radiation). It is shown that, in the range 450 to 600 cm−1, our findings are in good agreement with the widely used Mlawer, Tobin-Clough, Kneizys-Davies (MT_CKD) continuum. Below 450 cm−1 however the MT_CKD model overestimates the magnitude of the continuum coefficient. Sun, 28 Sep 2008 22:58:59 GMT http://hdl.handle.net/2122/4084 Title: Reply to comment by Rolf Müller and Simone Tilmes on ‘‘Middle atmospheric O3, CO, N2O, HNO3, and temperature profiles during the warm Arctic winter 2001–2002’’ <br/> <br/>Authors: Muscari, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; de Zafra, R. L.; Department of Physics and Astronomy, and Institute for Terrestrial and Planetary Atmospheres, State University of New York, Stony Brook, New York, USA <br/> <br/>Abstract: [1] Muscari et al. [2007] (hereafter referred to as M07) analyzed Arctic winter stratospheric conditions for 2001–2002 by means of ground-based measurements of stratospheric trace gases and temperature from Thule Air Base, Greenland (76.5°N, 68.7°W). The paper characterized stratospheric air masses observed over Thule from 20 January to 5 March 2002. Topics that were discussed included: the passage of both the polar vortex and the Aleutian high over Thule, with significant changes in ozone mixing ratio and temperature values; variations of measured O3 total column; vertical descent of air masses observed by means of CO measurements; observations of "ozone pockets" [Manney et al., 1995]; the correlation between illumination fraction and ozone mixing ratio at 900 K, indicating the relative significance of dynamics and photochemistry on ozone concentration at this altitude; the complete absence of polar stratospheric clouds, as concurrently monitored with a lidar system at Thule; and a qualitative (not quantitative) estimation of local ozone deficiency by means of N2O/O3 correlations. Müller and Tilmes [2008] (hereafter referred to as MT08) question the significant ozone deficiencies reported by M07 inside the vortex, which, as also pointed out by M07, are difficult to explain by heterogeneous chemistry during the warm winter 2001–2002. Nonetheless, M07 did speculate that heterogeneous activation of halogen compounds during mid-December and early January could have been the origin of the substantial ozone deficiency observed at the end of January/beginning of February in the small portion of the vortex core sampled by the Ground-Based Millimeter-Wave Spectrometer (GBMS). MT08 question this claim, as it "cannot be reconciled with the current understanding of halogen driven chemical ozone destruction in the Arctic." They suggest flaws in the N2O selection criteria used by M07 in order to identify intravortex N2O/O3 correlations, arising from their contention that GBMS measurements of N2O do not have the necessary spatial resolution needed for the task. MT08 favor instead the use of Potential Vorticity (PV) fields from European Centre Medium-Range Weather Forecasts (ECMWF) analyses. [2] As a result of the criticism of MT08, we have looked at N2O/O3 correlations from independent measurements carried out by the Odin Sub-Millimeter Radiometer (Odin/SMR) [Murtagh et al., 2002] and have also reprocessed the GBMS O3 measurements using a different deconvolution technique. The GBMS O3 reanalysis furnishes a significantly smaller qualitative estimate of local ozone loss (here and in the following we use "ozone loss" specifically to indicate an ozone deficiency due to heterogeneous activation of halogen compounds) and is consistent with the Odin/SMR data (section 2). This has resulted in a corrected and enriched version of Figure 9a of M07 (see Figure 2 in section 2). Although we value the comments of MT08 which prompted us to reanalyze GBMS ozone data, correcting and improving Figure 9 of M07 and the related discussion, we do reject some of the comments of MT08 concerning the N2O selection criteria used by M07, and reiterate the choice of GBMS N2O measurements rather than ECMWF PV values to separate air masses located inside, outside, or at the edge of the polar vortex (section 3). Furthermore, we stress that the use of N2O/O3 correlation curves to determine ozone loss inside the vortex, in particular near its edge (a region often called "the outer vortex"), can indeed cause an overestimation of local ozone loss near the vortex edge region and possibly also an overestimation of the vortex averaged loss (section 4). <br/> <br/>Description: Reply to comment by Rolf Müller and Simone Tilmes on "Middle atmospheric O3, CO, N2O, HNO3, and temperature profiles during the warm Arctic winter 2001–2002" Fri, 19 Sep 2008 22:58:59 GMT