Recent uplift and hydrothermal activity at Tangkuban Parahu volcano, west Java, Indonesia     

John Dvorak  Johannes Matahelumual  Arnold T Okamura  Harun Said  Thomas J Casadevall  Dedi Mulyadi 《Bulletin of Volcanology》1991,53(1):20-28

Tangkuban Parahu is an active stratovolcano located 17 km north of the city of Bandung in the province west Java, Indonesia. All historical eruptive activity at this volcano has been confined to a complex of explosive summit craters. About a dozen eruptions-mostly phreatic events- and 15 other periods of unrest, indicated by earthquakes or increased thermal activity, have been noted since 1829. The last magmatic eruption occurred in 1910. In late 1983, several small phreatic explosions originated from one of the summit craters. More recently, increased hydrothermal and earthquake activity occurred from late 1985 through 1986. Tilt measurements, using a spirit-level technique, have been made every few months since February 1981 in the summit region and along the south and east flanks of the volcano. Measurements made in the summit region indicated uplift since the start of these measurements through at least 1986. From 1981 to 1983, the average tilt rate at the edges of the summit craters was 40–50 microradians per year. After the 1983 phreatic activity, the tilt rate decreased by about a factor of five. Trilateration surveys across the summit craters and on the east flank of the volcano were conducted in 1983 and 1986. Most line length changes measured during this three-year period did not exceed the expected uncertainty of the technique (4 ppm). The lack of measurable horizontal strain across the summit craters seems to contradict the several years of tilt measurements. Using a point source of dilation in an elastic half-space to model tilt measurements, the pressure center at Tangkuban Parahu is located about 1.5 km beneath the southern part of the summit craters. This is beneath the epicentral area of an earthquake swarm that occurred in late 1983. The average rate in the volume of uplift from 1981 to 1983 was 3 million m³ per year; from 1983 to 1986 it averaged about 0.4 million m³ per year. Possible causes for this uplift are increased pressure within a very shallow magma body or heating and expansion of a confined aquifier.  相似文献   

Flow reactor and triple quadrupole mass spectrometer investigations of negative ion reactions involving nitric acid: Implications for atmospheric HNO3 detection by chemical ionization mass spectrometry     

O. Möhler  F. Arnold 《Journal of Atmospheric Chemistry》1991,13(1):33-61

Atmospheric nitric acid measurements by ACIMS (Active Chemical Ionization Mass Spectrometry) are based on ion-molecule reactions of CO₃ ^-(H₂O) _n and NO₃ ^-(H₂O) _n with HNO₃. We have studied these reactions in the laboratory using a flow tube apparatus with mass spectrometric detection of reactant and product ions. Both product ion distributions and rate coefficients were measured. All reactions were investigated in an N₂-buffer (1–3 hPa) at room temperature. The reaction rate coefficients of OH^-, O₂ ^-, O₃ ^-, CO₄ ^-, CO₃ ^-, CO₃ ^-H₂O, NO₃ ^-, and NO₃ ^-H₂O were measured relative to the known rate k=3.0×10^-9 cm³ s^-1 for the reaction of O^- with HNO₃. The main product ion of the reaction of CO₃ ^-H₂O with HNO₃ was found to be (CO₃HNO₃)^- supporting a previous suggestion made on the basis of balloon-borne ACIMS measurements. For the reaction of bare CO₃ ^- with HNO₃ three product ions were observed, namely NO₃ ^-, (NO₃OH)^-, and (CO₃HNO₃)^-. The reaction rate coefficients for CO₃ ^-H₂O (1.7×10^-9 cm³ s^-1) and NO₃ ^-H₂O (1.6×10^-9 cm³ s^-1) were found to be close to the collision rate. The measured k values for bare CO₃ ^- (1.3×10^-9 cm³ s^-1) and NO₃ ^- (0.7×10^-9 cm³ s^-1) are somewhat smaller. The collisional dissociations of CO₃ ^-(H₂O) _n , NO₃ ^-(H₂O) _n (n=1, 2), (CO₃HNO₃)^- and (NO₃HNO₃)^-, occasionally influencing ACIMS measurements, were also studied. Fragment ion distributions were measured using a triple quadrupole mass spectrometer. The results showed that previous stratospheric nitric acid measurements were unimpaired from collisional dissociation processes whereas these processes played a major role during previous tropospheric measurements leading to an underestimation of nitric acid concentrations. Previous ACIMS HNO₃ detection was also affected by the conversion of CO₃ ^-(H₂O) _n to NO₃ ^-(H₂O) _n due to ion source-produced neutral radicals. A novel ACIMS ion source was developed in order to avoid these problems and to improve the ACIMS method.  相似文献   

The sensitivity of artificially sedimented organic-free illitic clay: A reply     

R. Pusch  M. Arnold 《Engineering Geology》1970,4(4):357-358

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Die westatlantische Äquatoriale Gegenströmung seit hundert Jahren bekannt     

Arnold Schumacher 《Ocean Dynamics》1953,6(4-6):224-226

Summary An official French publication of 1852 is discussed which, by text and accompanying current chart, clearly points out the phenomenon of a Counter Current in the equatorial latitudes of the Western Atlantic.

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Le contre-courant équatorial en océan Atlantique Ouest connu depuis cent ans

Résumé L'article précédent traite le chapitre sur les courants généraux de l'Atlantique d'une publication officielle du Dépôt Général de la Marine Française de l'année 1852, dont le texte et la carte signalent le phénomène d'un contre-courant dans les régions équatoriales de l'Atlantique Ouest.

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The Virgin Forest Harvest and the Development of Colonial New Zealand     

Rollo Arnold 《New Zealand geographer》1976,32(2):105-126

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Scenarios for a 2 °C world: a trade-linked input–output model with high sector detail     

Arjan De Koning  Gjalt Huppes  Sebastiaan Deetman  Arnold Tukker 《Climate Policy》2016,16(3):301-317

In this study a scenario model is used to examine if foreseen technological developments are capable of reducing CO₂ emissions in 2050 to a level consistent with United Nations Framework Convention on Climate Change (UNFCCC) agreements, which aim at maximizing the temperature rise to 2 °C compared to pre-industrial levels. The model is based on a detailed global environmentally extended supply–use table (EE SUT) for the year 2000, called EXIOBASE. This global EE SUT allows calculating how the final demand in each region drives activities in production sectors, and hence related CO₂ emissions, in each region. Using this SUT framework, three scenarios have been constructed for the year 2050. The first is a business-as-usual scenario (BAU), which takes into account population, economic growth, and efficiency improvements. The second is a techno-scenario (TS), adding feasible and probable climate mitigation technologies to the BAU scenario. The third is the towards-2-degrees scenario (2DS), with a demand shift or growth reduction scenario added to the TS to create a 2 °C scenario. The emission results of the three scenarios are roughly in line with outcomes of typical scenarios from integrated assessment models. Our approach indicates that the 2 °C target seems difficult to reach with advanced CO₂ emission reduction technologies alone.

Policy relevance

The overall outlook in this scenario study is not optimistic. We show that CO₂ emissions from steel and cement production and air and sea transport will become dominant in 2050. They are difficult to reduce further. Using biofuels in air and sea transport will probably be problematic due to the fact that agricultural production largely will be needed to feed a rising global population and biofuel use for electricity production grows substantially in 2050. It seems that a more pervasive pressure towards emission reduction is required, also influencing the basic fabric of society in terms of types and volumes of energy use, materials use, and transport. Reducing envisaged growth levels, hence reducing global gross domestic product (GDP) per capita, might be one final contribution needed for moving to the 2 °C target, but is not on political agendas now.  相似文献   

Statistical treatment of fluvial dose distributions from southern Colorado arroyo deposits   总被引：1，自引：0，他引：1  

L.J. Arnold  R.M. Bailey  G.E. Tucker 《Quaternary Geochronology》2007,2(1-4):162-167

Many of the small-scale arroyo systems found across southern Colorado contain well-preserved sedimentary records of prehistoric fluvial erosion and aggradation epicycles. In the following paper, we date a set of 50 ephemeral fluvial samples from four southern Colorado arroyo systems using a combination of single-grain and single-aliquot OSL techniques. Analysis of the sample D_e distribution characteristics reveals that these arroyo sediments were subjected to a diverse array of bleaching conditions prior to deposition. The use of appropriate burial dose estimation procedures is therefore deemed vital to ensuring that accurate age estimates are produced for each of these samples. In this study we apply the formal ‘age model’ decision procedures of Bailey and Arnold [Statistical modelling of single-grain quartz D_e distributions and an assessment of procedures for estimating burial dose. Quaternary Science Reviews, in press.] and Arnold [2006. Optical dating and computer modelling of arroyo epicycles in the American Southwest. D.phil. Thesis, University of Oxford, unpublished] to our fluvial sample dataset in order to enable a more objective selection of appropriate burial dose estimates. The resultant OSL chronostratigraphies are examined and discussed. These formal decision procedures yield sample ages that are stratigraphically consistent for 94% of the 50 fluvial samples examined. The resulting OSL ages also display a greater degree of stratigraphic consistency in comparison to those ages that would have been generated by simply applying a single type of age model to all samples.  相似文献   

Improved method for the optical determination of temperature profiles     

Arnold L. Friend  Charles R. Stearns 《Boundary-Layer Meteorology》1970,1(2):227-239

The vertical temperature profile in the lower atmosphere was determined at heights from 60 cm to 180 cm from estimates of optical refraction obtained from photographs of illuminated targets over the ice of Lake Mendota, Madison, Wisconsin, during the winter of 1968. The targets consist of several equally spaced fluorescent lamps with the long axis along a line slanted 45 ° to the ice. Two targets were placed 750 m and 1500 m from the camera. A simplified model relating lapse rate to the radius of curvature of a light ray is used for computation. Results show that the technique is more reliable for estimates of profile shape than for estimates of lapse rate values.  相似文献   

Numerical investigations on the correction term for the free air anomalies according to the new theory of dynamical geodesy     

Kurt Arnold  Dietrich Schoeps  Lothar Stange 《Studia Geophysica et Geodaetica》1965,9(2):160-160

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The deflections of the vertical expressed in free-air anomalies and their relationship to the gravimetric-isostatic deflections     

K. Arnold 《Journal of Geodesy》1962,36(3):259-264

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