bluuebunny/crossref_metadata_2025 huggingface dataset:
Moment tensor inversion from Mednet data (1) large worldwide earthquakes of 1990
Authors: Giardini Domenico
Published: February 2008

We develop a method for the rapid determination of the moment tensor of large worldwide earthquakes, by inversion of long‐period data recorded by the MedNet regional network, and we apply it to the most significant events of 1990: March 3 (Fiji) and 25 (Costa Rica), May 12 (Sakhalin), 20 (Sudan) and 30 (Romania), June 20 (Iran), July 16 (Luzon) and December 30 (New Britain). The comparison with CMTs and moment tensors by USGS shows that an advanced regional seismic network is capable of providing reliable and rapid control of the seismic source for worldwide seismicity.
Quasi 16‐day oscillation in the ionosphere
Authors: Forbes Jeffrey M. , Leveroni Susanna
Published: February 2008

A quasi 16‐day oscillation is discovered in the E‐ and F‐regions of the equatorial ionosphere during January/February 1979, apparently connected with the upward penetration of a free Rossby mode excited in the winter stratosphere. The observed effects are interpreted in terms of electric fields induced by the ionospheric wind dynamo.
The November 13, 1990 Earthquake off the coast of the Primorskij Region, The Eastern Russia
Authors: Nakanishi Ichiro , Moriya Takeo , Endo Masao , Motoya Yoshinobu
Published: February 2008

We study the November 13, 1990 off‐Primorskij earthquake, which occurred near the northern end of the Japan Sea off the coast of the Primorskij region, by using data from short‐period and broad‐band seismograph networks in Hokkaido, Japan. The main shock and four aftershocks are located from arrival times of P‐ and S‐waves recorded by these networks. The main shock epicenter is located about 50 km off the coast at a depth of about 10 km, and the largest aftershock is located about 20 km southwest of the main shock. It is difficult to read the polarities of P‐waves recorded by the short‐period network; the source mechanism of the main shock is determined by moment tensor inversion of long‐period wave‐forms recorded by broad‐band instruments. The source mechanism is characterized by a reverse faulting with a vertical T‐axis and a horizontal P‐axis trending in the WNW‐ESE direction. We have examined earthquake data reported by the ISC and by the Academy of Sciences of the USSR to study previous seismicity in the vicinity of the November 13 earthquake; no significant well‐located earthquake is reported in this region. The stress orientation in this region may have significant implications for the tectonics of the northern end of the Japan Sea, where a plate boundary between the Eurasian and North American plates has been proposed.
First paleomagnetic evidence for rotation of the Ionian Zone of Albania
Authors: Speranza F. , Kissel C. , Islami I. , Hyseni A. , Laj C.
Published: February 2008

A paleomagnetic study of 170 samples obtained from 15 sites from Cretaceous, Eocene and Oligocene sedimentary rocks documents a ∼45° clockwise rotation of the Albanian Ionian zone. This rotation is certainly post‐Eocene and most probably post‐Oligocene. These results show that the entire Ionian zone has undergone a semi rigid rotation about a pole of rotation situated farther north than previously believed.
Thermal survey of Mount Etna Volcano from space
Authors: Bonneville A. , Gouze P.
Published: February 2008

Surveys of ground thermal anomalies and the monitoring of their evolution are of great importance in the study of volcanoes. Thermal monitoring techniques could be used in conjunction with classical monitoring tools (i.e. seismological and deformation networks), to give better predictions of the onset of a volcanic event. In order to detect and emphasize small anomalies in the surface temperature of the ground, we have developed a new method based on the joint use of two satellite radiometers: the NOAA‐Advanced Very High Resolution Radiometer (AVHRR) for the quality of its thermal band calibration and the Landsat Thematic Mapper (TM) for its high spatial resolution. This method is applied to the Mount Etna volcano, Sicily, and reveals several thermal anomalies. One anomaly is already known, and is associated with the permanently active craters of the summit zone. The second is a larger area where an eruption occurred one week after the data acquisition (10/23/86). The general trend of the thermal anomalies leads to recognition of a large, semi‐circular intrusive zone corresponding to the borders of the well‐known Valle del Bove.
Injection of electrons and protons with energies of tens of MeV into L < 3 on 24 March 1991
Authors: Blake J. B. , Kolasinski W. A. , Fillius R. W. , Mullen E. G.
Published: February 2008

On 24 March 1991 instrumentation aboard CRRES observed the almost instantaneous injection of electrons and protons with energies above 15 MeV into the L‐region 2 < L < 3. The energy spectrum of the injected electrons, a power law (E−6) peaked at 15 MeV and continued to at least 50 MeV
On the formation and sedimentation of stratospheric nitric acid aerosols: Implications for polar ozone destruction
Authors: Arnold F. , Petzoldt K. , Reimer E.
Published: February 2008

The formation and sedimentation of nitric acid‐aerosols (NA‐aerosols) in the winter polar stratosphere is investigated in the light of recent mass spectrometric in‐situ measurements of gaseous nitric acid performed in the winter arctic stratosphere. We revisit the nitric acid measurements and extend their interpretation by carrying out isentropic trajectory calculations of the airmasses encountered in these experiments and by considering aerosol measurements, which became available recently. Our analysis shows that the mass spectrometer measurements provide strong evidence for nitric acid nucleation and vertical redistribution of nitric acid due to sedimentation of HNO3‐containing aerosols. Both these processes promote halogen‐catalysed destruction of ozone. Moreover, it is concluded that nitric acid nucleation is less efficient than expected from simple equilibrium considerations. Probably, this is due to rapid cooling and inefficient nucleation (inefficient activation of preexisting H2SO4/H2O‐aerosols for HNO3/H2O‐condensation) allowing only a small fraction of the preexisting H2SO4/H2O‐aerosols to serve as active nuclei.
Bichromatic excitation of long‐period Rayleigh and air waves by the Mount Pinatubo and El Chichon volcanic eruptions
Authors: Widmer R. , Zürn W.
Published: February 2008

We have detected a new powerful source of low‐frequency seismic energy which is associated with some violent volcanic eruptions. For the two eruptions for which we have identified this new source the spectrum is bichromatic, consisting of two narrow, phase coherent spectral lines. These bands were centered on 3.76 and 5.14 mHz for the April 4, 1982 El Chichón eruption, and on 3.68 and 4.44 mHz for the June 15, 1991 Mt. Pinatubo eruption. During the latter, 8 hour long eruption the resonance frequencies varied by less than 20 μHz. The strength of the source is sufficient to excite globe circling surface waves. We conclude from these observations that volcanoes can excite “harmonic tremors” at much longer periods than previously observed. Our preferred source model involves feedback between local atmospheric oscillations and the eruption process. The physics responsible for this feedback remains subject to speculations.
The Hudson Bay free‐air gravity anomaly and glacial rebound
Authors: James Thomas S.
Published: February 2008

Current models of the Laurentide deglaciation predict only 15% to 30% of the observed Hudson Bay Free‐air gravity anomaly low. Unless these models are able to be modified, the source of the remainder of this Free‐air gravity anomaly must be sought elsewhere, such as in mantle convection.
A Middle‐Triassic Paleomagnetic Pole for the Eurasian Plate from Heming (France)
Authors: Théveniaut H. , Besse J. , Edel J. B. , Westphal M. , Duringer P.
Published: February 2008

The paleomagnetic study of Middle Triassic limestones (91 cores, 160 samples) from a 40 m thick section in Heming (France) yields a paleomagnetic pole for stable Europe at lat=53.5°N, lon=140.8°E, dp=2.3°, dm=3.9°. This pole fills an important gap of the apparent polar wander path (APWP) of the Eurasian plate. The comparison of this pole with available data shows a standstill of the Eurasian plate from the Late Paleozoic to the Middle Triassic, followed by a rapid drift until the Lower Jurassic. The beginning of the rapid drift is contemporaneous with the initiation of main rifting processes in the Tethyan Oceans.
The rock magnetic fingerprint of chemical remagnetization in midcontinental Paleozoic carbonates
Authors: Jackson Mike , Sun Wei‐Wei , Craddock John P.
Published: February 2008

Results of a paleomagnetic and rock magnetic survey of Paleozoic carbonates from 39 sites in the midcontinental U.S. show that many of these sites carry a stable remanence of apparent Permian age. Many of these remagnetized sites also have relatively high anhysteretic susceptibilities, and higher saturation remanence than most of the sites where the late Paleozoic remanence is absent. However the correlation between late Paleozoic remanence and high anhysteretic susceptibility or high saturation remanence is imperfect. The most diagnostic rock magnetic parameter for recognizing remagnetized sites is a ratio of anhysteretic remanence/saturation remanence exceeding 10%. We have found high ratios in almost all remagnetized sites, but in very few sites where the Late Paleozoic remanence is absent. The high ratios reflect the presence of a significant fraction of extremely fine‐grained magnetite (a few tens of nanometers), spanning the superparamagnetic‐single domain threshhold.
A stochastic view of lower crustal fabric based on evidence from the Ivrea Zone
Authors: Holliger Klaus , Levander Alan R.
Published: February 2008

Despite its complicated history the Ivrea Zone is considered to be a representative surface exposure of extended continental crust. We have digitized two standard 1:25,000 geological maps from this area and evaluated their structural statistics. Because of the subvertical orientation of the Ivrea Zone these maps can be considered as small‐scale cross sections through the lower continental crust. The autocorrelation functions of the digitized lithologies measured from these maps show a clear self‐similar or fractal rather than a Gaussian or deterministic trend. We found that an anisotropic von Karman correlation function with an aspect ratio around 4 and a Hurst number of 0.3, corresponding to a fractal dimension of 2.7, matches the observed data. Our results represent an explicit confirmation of previous indirect evidence for the fractal nature of lithospheric heterogeneities and provide the means to construct realistic crustal‐scale seismic models of Ivrea‐type lower continental crust.
Crustal tilting derived from Holocene sea‐level observations along the east coast of Hokkaido in Japan and upper mantle rheology
Authors: Maeda Y. , Nakada M. , Matsumoto E. , Matsuda I.
Published: February 2008

Late Holocene sea‐level observations at sites along the east coast of Hokkaido in Japan indicate a gradual decrease of the altitude of relative sea‐level eastward toward the tip of Nemuro Peninsula. These observations in seismically active areas can be explained by glaciohydroisostatic adjustment due to the last déglaciation for an Earth model with a thin lithosphere of 30–40 km thickness and with no low viscosity layer, or with a 25 km lithosphère overlying a low viscosity layer less than 50 km, although more data as a function of time are needed to distinguish these models. Thus the vertical crustal displacement associated with the subduction of the Pacific plate seems to has not been cumulated on a time scale of 103–104 years.
Annual and semiannual waves in ozone as derived from SBUV vertical global ozone profiles
Authors: Varotsos C. , Helmis C. , Cartalis C.
Published: February 2008

Global averages of monthly ozone profile data obtained using the solar backscatter ultraviolet (SBUV) instrument, are analyzed for the period from November 1978 to September 1985. Differences between ozone profile data for Umkehr layers 4 to 10 ‐ from 19 km to 53 km, approximately ‐ and the deseasonalized ozone data are first estimated for the entire time period at all Umkehr layers, and are then Fourier analyzed to obtain the amplitude, phase and percentage contribution to the total variance of the first and second harmonics. It is found that the annual wave in global ozone is strong in the high and low stratosphere and weak in the middle stratosphere, whereas the semiannual wave in global ozone is strong in the middle stratosphere. Global ozone deviations at Umkehr layer 7 are compared to the 10.7 cm solar flux to yield a strong positive correlation for the entire period, which implies that the quasi‐semiannual wave in global ozone depends on the quasi‐semiannual wave of the 10.7 cm solar flux.
Several‐fold enhancement of biologically effective ultraviolet radiation levels at McMurdo Station Antarctica during the 1990 ozone “hole”
Authors: Stamnes Knut , Jin Zhonghai , Slusser James , Booth Charles , Lucas Timothy
Published: February 2008

Spectral measurements of biologically relevant radiation at McMurdo Station, Antarctica reveal ultraviolet (UV) irradiance levels at 305 nm in October exceeding by a factor between 3 and 6 “normal” values expected for undepleted ozone levels. This enhancement is directly related to the ozone depletion. The column abundance of stratospheric ozone derived from these measurements was as low as 145 Dobson Units (DU) in October, 1990. This is more than a factor of 2 lower than the value at solstice, and 100 DU less than in October, 1988. The dose rate for damage to the DNA molecule based on Setlow's action spectrum and UV radiation measured at noon is well above normal levels most of the time between October 1 and December 5 and is as much as three times the normal value for a few days at the end of October.
Vertical profiles of ozone at McMurdo Station, Antarctica; Spring 1991
Authors: Johnson B. J. , Deshler T. , Thompson R. A.
Published: February 2008

Forty‐three vertical profiles of ozone and temperature were measured at McMurdo Station, Antarctica, from 23 August to 1 November 1991. The data showed severe ozone depletion, during the springtime, for the third consecutive year. The lowest total column ozone, 146 DU on 10 October, was equal to the minimum measured in 1990, while the 18 ± 1 km ozone mixing ratio on this day was 0.1 ppmv, a factor of 2 below the previous minimum observed at this altitude. Most of the ozone depletion was once again confined to the 12–20 km layer, where an 83% reduction (105 DU to 18 DU) was observed, although there were also signs of depletion occurring in the 24–30 km region and below 12 km. Intrusions of ozone‐rich air above 20 km caused substantial increases in total ozone during two periods when McMurdo was near or within the polar vortex wall.
Energetic particle composition variations during the March 1991 events measured with the Ulysses EPAC instrument
Authors: Krupp N. , Keppler E. , Fränz M. , Korth A. , Witte M. , Moussas X. , Blake J. B. , Naidu K. , Quenby J. J. , Woch J. , Balogh A. , Bame S.
Published: February 2008

We report on energetic particle measurements obtained with the EPAC instrument on board the Ulysses spacecraft during March 1991, when a series of important flares occurred at the Sun. The EPAC instrument measures electrons (0.1–0.38 MeV), protons (0.3–1.5 MeV) and heavy ions (0.2–6.0 MeV/N). We discuss the time interval March 22 through March 29 (DOY 81 through 88) and divide this interval in three periods with different ion compositions. At a quasi‐perpendicular shock on March 23, shock drift acceleration of protons, helium and electrons was observed. Thirteen hours after this shock the energetic ion composition changed dramatically by almost two orders of magnitude, signalling the arrival of a coronal mass ejection (CME) or driver gas. This driver gas was still present at the spacecraft when a second quasi‐perpendicular shock passed the spacecraft. The ratio Fe/O increased from 0.6 to 1.0 indicative of a connection to solar particles for about 6 hours after the second shock. The second shock did not accelerate ions as well and electrons not at all. Six hours after this shock the same oxygen and iron composition was observed as before, indicating that the second shock did not alter the energetic ion composition. A third ion composition was observed before the driver gas disappeared which was significantly different from those observed before the first and between the two shocks.
Regression analysis for anomalous changes of ground water level due to earthquakes
Authors: Matsumoto Norio
Published: February 2008

A multiple regression analysis method is applied to detect anomalous changes of ground water level due to earthquakes. Corrected water level is calculated by eliminating responses due to barometric pressure, earth tide and precipitation from the observed water level based on a model obtained by the minimum AIC (Akaike Information Criterion) procedure. The data observed at Haibara well, Shizuoka, central Japan during the period from Feb. 1981 to Dec. 1990 is analyzed using this method. It is shown that the corrected water level decreases more than 1 cm after each of fifteen earthquakes.
Isothermal compression of molten Fe2SiO4
Authors: Agee Carl B.
Published: February 2008

Isothermal compressions of molten Fe2SiO4 have been measured between 1.0 and 5.5 GPa in a piston‐cylinder apparatus by observing sinking and floating of ruby and garnet buoyancy markers of known composition and density. For liquid Fe2SiO4, (dρ/dP)1773K is 0.080 g cm−3 GPa−1 in the pressure range investigated. The static compression sink/float density measurements, when combined with the 105 Pa reference density from Shiraishi et al. [1978], yield a third order Birch‐Murnaghan bulk modulus for molten Fe2SiO4 of K1773K=24.4 GPa with a pressure derivative dK/dP=10.1.
Spectral characteristics of shuttle glow
Authors: Viereck R. A. , Mende S. B. , Murad E. , Swenson G. R. , Pike C. P. , Culbertson F. L. , Springer R. C.
Published: February 2008

The glowing cloud near the ram surfaces of the Space Shuttle was observed with a hand‐held, intensified spectrograph operated by the astronauts from the aft‐flight‐deck of the space shuttle. The spectral measurements were made between 400 and 800 nm with a resolution of 3 nm. Analysis of the spectral response of the instrument and the transmission of the shuttle window was performed on orbit using earth‐airglow OH Meinel bands. This analysis resulted in a correction of the shuttle glow intensity in the spectral region between 700 and 800 nm. The data presented in this report is in better agreement with laboratory measurements of the NO2 continuum.
The deduction of in‐track winds from satellite measurements of density and composition
Authors: Moe Kenneth , Moe Mildred M.
Published: February 2008

A method is proposed for obtaining the in‐track wind component by exploiting the different ways in which two satellite‐borne instruments interact with the airstream. It makes possible the completion of the three‐dimensional wind vector from measurements which yield at most two components. This is especially important during geomagnetic storms when winds can cause serious errors in density measurements made by a single instrument. The method can be used to retrieve valuable information from existing data bases which contain measurements by three‐axis accelerometers and chambered instruments such as closed‐source mass spectrometers or pressure gages.
Enhancement of Thomson scatter by charged aerosols in the polar mesosphere: Measurements with a 1.29‐GHz radar
Authors: Cho John Y. N. , Kelley Michael C. , Heinselman Craig J.
Published: February 2008

The summer polar mesosphere was observed with the Sondrestrom 1.29‐GHz radar with a new high‐resolution data acquisition mode. On one occasion, a spatially narrow enhancement in the backscattered power was seen near an altitude of 88 km. We discuss possible explanations and propose that this layer may be the first example of polar mesosphere summer echoes (PMSE) detected above 1 GHz. Specifically, we suggest that these echoes are enhanced Thomson scatter from a layer of charged aerosols, and we speculate upon the size and charge state.
Laboratory simulation of explosive volcanic loading and implications for the cause of the K/T boundary
Authors: Gratz A. J. , Nellis W. J. , Hinsey N. A.
Published: February 2008

Intense explosive volcanism was simulated by preheating samples to 600°C and subjecting them to dynamic stress pulses of 0.9 and 1.3 GPa. The resultant ejecta was examined optically and by transmission electron microscopy (TEM). Deformation and failure was entirely by brittle fracture, and most fractures were irregular and intergranular. None of the features typical of K/T boundary sediments and of ejecta from meteorite impact craters (planar deformation features, amorphization, mosaicism) were observed; there were also no signs of intracrystalline plasticity. We conclude that explosive volcanism is incapable of producing the microstructural features seen at the K/T boundary, and that they must have been caused by impact of a large meteorite.
Low‐energy solar electrons and ions observed at Ulysses February‐April, 1991: The inner heliosphere as a particle reservoir
Authors: Roelof E. C. , Gold R. E. , Simnett G. M. , Tappin S. J. , Armstrong T. P. , Lanzerotti L. J.
Published: February 2008

Ulysses observations at 2.5 AU of 38–315 keV electrons and 61–4752 keV ions during February‐April 1991 suggest in several ways that, during periods of sustained high solar activity, the inner heliosphere serves as a “reservoir” for low‐energy solar particles. Particle increases were not associated one‐to‐one with large X‐ray flares because of their poor magnetic connection, yet intensities in March‐April remained well above their February levels. The rise phase of the particle event associated with the great flare of 2245UT March 22 lasted most of two days, while throughout the one‐week decay phase, the lowest‐energy ion fluxes were nearly equal at Ulysses and Earth (IMP‐8).
Transport of the Norwegian Atlantic Current as determined from satellite altimetry
Authors: Pistek Pavel , Johnson Donald R.
Published: February 2008

Relatively warm and salty North Atlantic surface waters flow through the Faeroe‐Shetland Channel into the higher latitudes of the Nordic Seas, preserving an ice‐free winter environment for much of the exterior coast of northern Europe. In this study, we have monitored this flow along the Norwegian coast using GEOSAT altimetry on two ascending arcs during the Exact Repeat Mission in 1987–1989. Concurrent undertrack CTD surveys were used to fix a reference surface for the altimeter‐derived sea surface height (SSH) anomalies, in effect creating time series of alongtrack surface dynamic height topographies. Climatologic CTD casts were then used, with empirical orthogonal function (EOF) analysis, to derive relationships between historical surface dynamic heights and vertical temperature and salinity profiles. Applying these EOF relationships to the altimeter signals, we calculated mean transports of volume, heat and salt at approximately 2.9 Sverdrups, 8.1 × 1011 KCal/s and 1.0 × 108 Kg/s, respectively. Although strong variability occurred, a clear seasonal signal could be seen with summer to winter variations of about 50% of the means. Maximum transports occurred in February/March and minimum in July/August.
3‐D tropospheric CO modeling: The possible influence of the ocean
Authors: Erickson David J. , Taylor John A.
Published: February 2008

The ocean has long been known to be both a source and sink of climate reactive trace species. Recently, satellite data and general circulation models have been used to simulate air‐sea exchange inventories with high resolution and global coverage. Here, we discuss the differences between a 3‐D global atmospheric CO transport model run with a homogeneous ocean to atmosphere CO flux (35 Tg CO yr−1), and a larger spatially and temporally varying ocean CO flux (153 Tg CO yr−1). Both ocean sources of atmospheric CO are within previous estimates of the ocean to atmosphere flux. The model sensitivity calculations show that the ocean can account for between 5 – 50 % of the total surface level atmospheric CO pool, over large areas of the northern and southern hemisphere oceans. Oceanic CO fluxes to the atmosphere are important in both hemispheres, with a greater relative influence occurring in the southern hemisphere. Seasonal cycle calculations indicate that area‐weighted CO concentrations in the remote southern and northern hemisphere marine troposphere are most heavily influenced by the ocean source during summer months. The main source of CO in surface ocean waters is thought to be photochemical oxidation of organic matter. Any climate related changes in surface radiative fluxes, due to ozone depletion or other processes, may alter surface ocean CO concentrations and by implication atmospheric marine boundary layer CO, OH and O3 abundance.
Cooling rate of an active Hawaiian lava flow from nighttime spectroradiometer measurements
Authors: Flynn Luke P. , Mouginis‐Mark Peter J.
Published: February 2008

A narrow‐band spectroradiometer has been used to make nighttime measurements of the Phase 50 eruption of Pu'u O'o, on the East Rift Zone of Kilauea Volcano, Hawaii. On February 19, 1992, a GER spectroradiometer was used to determine the cooling rate of an active lava flow. This instrument collects 12‐bit data between 0.35 to 3.0 μm at a spectral resolution of 1 – 5 nm. Thirteen spectra of a single area on a pahoehoe flow field were collected over a 59 minute period (21:27 – 22:26 HST) from which the cooling of the lava surface has been investigated. A two‐component thermal mixing model [Flynn, 1992] applied to data for the flow immediately on emplacement gave a best‐fit crustal temperature of 768°C, a hot component at 1150°C, and a hot radiating area of 3.6% of the total area. Over a 52‐minute period (within the time interval between flow resurfacings) the lava flow crust cooled by 358°C to 410°C at a rate that was as high as 15°C min−1. Our observations have significance both for satellite observations of active volcanoes and for numerical models of the cooling of lava flows during their emplacement.
Segregation of high pressure partial melts from peridotite using aggregates of diamond: A New experimental approach
Authors: Johnson Kevin T. M. , Kushiro Ikuo
Published: February 2008

Recent theoretical, observational, and experimental evidence from mid‐ocean ridges suggests that mantle permeability is large enough at small melt fractions to permit segregation of very small amounts of melt. Yet experiments to study the chemical characteristics of small partial melt fractions have not been performed. We report a new experimental technique that achieves segregation of small percentages of melt from a peridotite source using a porous layer of diamond chips adjacent to the peridotite. With this configuration, experiments were conducted using piston‐cylinder apparatus at 15 kb and 1425°C over a range of times. Melts produced by this method do not suffer from crystal growth in the melt upon quenching and, since they are direct products of melting of the peridotite source, do not contain introduced basaltic components as in sandwich techniques. We show that while melts produced in short duration runs are not in equilibrium with the residue, equilibrium is approached in the longer duration runs. This new technique may be adapted to address questions of melt generation in the mantle.
Black carbon (soot) aerosol in the lower stratosphere and upper troposphere
Authors: Pusechel R. F. , Blake D. F. , Snetsinger K. G. , Hansen A. D. A. , Verma S. , Kato K.
Published: February 2008

As determined by impactor samplers flown on ER‐2 and DC‐8 aircraft, black carbon aerosol (BCA) mass loadings in the stratosphere average 0.6 nanograms per standard cubic meter, or 0.01% of the total aerosol. Upper tropospheric BCA increases to 0.3%. Low stratospheric concentration is commensurate with present commercial air traffic fuel consumption, given the following assumptions: the BCA emissions are 0.1 grams per kilogram of fuel consumed, 10% of route mileage is above the tropopause, and average BCA stratospheric residence time is about one year. Taking BCA into account, the stratospheric single scatter albedo is ≈0.99. Using parameters for planned supersonic commercial aircraft, whose emissions will be predominantly in the stratosphere, we show that such traffic will double stratospheric BCA concentration. This would reduce the aerosol single scattering albedo by one percent, and double the BCA surface area that is available for heterogeneous chemistry.
A description of low‐frequency atmospheric oscillations over the extratropical Northern Hemisphere using singular spectrum analysis
Authors: Elsner J. B.
Published: February 2008

The method of singular spectrum analysis (SSA) is used to describe low‐frequency atmospheric variability over the extratropical Northern Hemisphere (NH) from 500 hPa geopotential heights. Analysis reveals significant intraseasonal and interannual oscillations confined principally to eastern sections of the Pacific Ocean and northern sections of the Atlantic Ocean, generally where earlier studies have identified persistent anomalies. From the results it is suggested that persistent anomalies may undergo significant modulation on the quasi‐biennial time scale.
Radiative influences of pinatubo volcanic aerosols on twilight observations of NO2 column abundances
Authors: Perliski Lori M. , Solomon Susan
Published: February 2008

Following the massive eruption of Mt. Pinatubo during June of 1991, twilight slant column abundances of NO2 were observed to decrease by 30–40% at Lauder, New Zealand (45°S). Johnston et al. [1992] proposed that at most, 10–15% of the observed decrease could be due to alterations of the effective optical path of light received by the detector associated with increased scattering, the balance likely being the result of heterogeneous conversion of odd‐nitrogen chemical species to nitric acid on the surfaces of the volcanic aerosols. In this study, it is shown that nearly all of the observed decrease in twilight NO2 slant column abundance is likely to be due to heterogeneous chemistry. Airmass factors calculated with a spherical Monte Carlo radiative transfer model are shown to be relatively insensitive to the presence of the Pinatubo volcanic aerosols above about 20 km, although some significant differences are obtained below this altitude. Changes in photolysis rates due to increased scattering are also shown to have only a small effect on the total twilight NO2 column abundances.
Crosshole lithotectonic correlation in high‐grade metamorphic rocks, central southern Connecticut
Authors: Goldberg David
Published: February 2008

Well logs, acquired in two scientific drill holes in central southern Connecticut near Moodus township and Gillette Casue State Park, measured the electrical, sonic, and natural radioactive properties of the rocks within and adjacent to the Honey Hill fault zone. A crosshole correlation was made with logs of these physical properties which shows distinct similarities between the metamorphic rocks encountered in each hole, even though they are separated by 8 mi (13 km). This log‐based correlation indicates that an anomalous interval associated with the Honey Hill fault contact maintains a 7 ft (2 m) thickness and an apparent dip of 2–3° between the two holes. The overlying interval, consisting mainly of the Tatnic Hill and Hebron formations, thins by about 150 ft (50 m) between Moodus and Gillette Castie, and the log responses which remain similar in character indicate that tectonic compaction of this interval has taken place. Log anomalies below the fault in the Avalon Complex rocks are attributed to regional fracturing and brecciation and also correlate between the holes. Differences between the holes in fine‐scale variation and absolute value of the logs are generally attributed to intrinsic mineralogy and/or localized structure. These log data enable the deformed rocks of the Tatnic Hill and Hebron formations and Avalon Complex rocks, including the Honey Hill fault zone, to be correlated crosshole, detailing the lithotectonic stratigraphy as a function of depth.
Relationships between tropospheric water vapor and surface temperature as observed by radiosondes
Authors: Gaffen Dian J. , Elliott William P. , Robock Alan
Published: February 2008

Using radiosonde data from 50 stations for 1973–1990, we quantify relationships between surface air temperature (Ts) and precipitable water vapor (W) for different time scales. Monthly mean observations are fairly well described by an equation of the form ln W = A + B Ts, but the coefficients A and B depend on the Ts range considered. At high Ts, the relationship is poor. This relationship and relationships between sea surface temperature (SST) and W based on satellite microwave observations over oceans are in remarkably good agreement over restricted SST ranges. Monthly and annual anomalies of W and Ts are well correlated only outside the tropics, but on longer time scales, there is some evidence of positive trends in both W and Ts at most of the stations studied. Thus the relationship between W and Ts depends on the time scales and geographic region considered.
Alfvénic noise and transient reconfiguration in a simulated current sheet
Authors: Rogers Catherine H. , Christiansen Peter J.
Published: February 2008

A magnetotail‐like structure is modelled using a 2‐dimensional, single‐ion species, electromagnetic, Darwin (no displacement current), particle‐in‐cell (PIC) code, which is a modified version of that described by Hamilton and Eastwood [1982]. The modifications include new boundary conditions for the magnetic fields which allow a non‐symmetrical topology to be modelled.

The work presented here is aimed at the construction and testing of a self‐consistent ‘steady‐state’ model. It is found that the model supports significant magnetic perturbations, arising as a consequence of cyclotron resonance interactions with ion beam‐like features. When subjected to transient changes in the convection electric field, the model also exhibits field reconfiguration and particle responses reminiscent of near‐Earth substorm behaviour.
Optical signatures of lightning‐Induced heating of the D region
Authors: Taranenko Y. N. , Inan U. S. , Bell T. F.
Published: February 2008

Lightning‐induced heating of the nighttime D region leads to the excitation of a number of lines of O, O2, N2,
at intensities of 10–109 Rayleighs (R) for vertical observations. For example, the 5577 Å emission from O has intensity ∼60 R lasting for ∼350 ms while the 1st and 2nd positive bands of N2 are at ∼109 R but last only ∼50μs.
Polar motions excited by a convecting viscous mantle
Authors: Moser Jiří , Yuen David A. , Matyska Ctirad
Published: February 2008

The role played by time‐dependent mantle convection on exciting long‐term polar motions is examined by means of a viscous model. For sufficiently low effective viscosity, polar‐wander speeds of 0(1 deg/Myr) would require contributions from the off‐diagonal elements of the inertia tensor, with magnitudes around 105 times smaller than those found in viscoelastic models used for postglacial rebound. Contributions from the large‐scale mantle flow to the angular momentum vector can be comparable to those due to changes in moment of inertia tensor for non‐linear rheology or for young planets. The relative roles of the two contributions depend on the non‐linear rheology of the mantle and its convective vigor.
A model for the computation of thermal expansivity at high compression and high temperatures: MGO as an example
Authors: Anderson Orson L. , Oda Hitoshi , Isaak Donald
Published: February 2008

We compute the value of the thermal expansivity α over a wide range of compression (η ≡ V/V0, 0.6 ≤ η ≤ 1.0) and temperature (300 K ≤ T ≤ 2500 K). Three methods are combined to find α. We utilize: 1) the high P,T data base from the PIB ab initio model for MgO, which specifies the Helmholtz energy and the volume and temperature derivatives; 2) the measured thermal expansivity and its various pressure and temperature derivatives; and 3) several thermodynamic identities relating T and V dependence of various physical properties.

We present a simple equation relating α to η along isochores and suggest values of α. for MgO over V, P, T conditions, including those of the earth's lower mantle. The parameters in the equation are evaluated by using the ab initio data base. We find that α varies from about 1.40αa to 0.40αa along a geotherm through the upper and lower mantle, where αa is α at ambient conditions.
Atmospheric contributions to non‐seasonal variations in the length of day
Authors: Naito Isao , Kikuchi Naokichi
Published: February 2008

Atmospheric wind and pressure contributions to non‐seasonal variations in the length of day (LOD) determined by the International Radio Interferometry Surveying are evaluated during the years of 1984–1991 using Japan Meteorological Agency data that include winds up to 10mb. We confirm that intra‐annual LOD variations are the result of tropospheric zonal wind changes, which include a pronounced quasi‐seven month oscillation in addition to the well‐known intra‐seasonal oscillation. It is also shown that inter‐annual LOD variations on time scales of two to five years are the superposed contributions from both a stratospheric quasi‐biennial oscillation and tropospheric low frequency variations of two‐to‐five year time scales in zonal wind. The residual LOD after removing these atmospheric contributions shows a decadal‐like variation, which may be caused by a core ‐ mantle coupling torque.
Pressure gradient structures in the tail neutral sheet as “roots of the arcs” with some effects of stochasticity
Authors: Galperin Yu. I. , Volosevich A. V. , Zelenyi L. M.
Published: February 2008

Westward cross‐tail current at the earthward edge of the plasma sheet is enhanced due to strongly stochastic (rLi ∼ Rc) ion motions. A narrow elongated magnetic field depression arises which leads to further stochastication of the ions convecting through it, and to a local increase of magnetostatic plasma pressure, enhanced lateral transport and removal of higher energy ions. This plasma structure can be stationary in the magnetospheric frame.

It is the “root” of sheet‐like auroral currents of stable auroral homogeneous arcs/bands (inverted‐V's) located at the equatorial edge of the steady premidnight auroral oval. The magnetic field minimum can be the location of a sub‐storm onset when it deepens below the stability threshold for reconnection/tearing.
Stress accumulation and release at complex transform plate boundaries
Authors: Verdonck David , Furlong Kevin P.
Published: February 2008

Finite element methods are used to model the dynamics of deformation along complex transform plate boundaries, specifically the San Andreas fault system, California. Effects of mantle rheology and fault geometry on the stress buildup and release are investigated. No prior knowledge of the earthquake cycle time or amount of fault slip is assumed and the results suggest that the San Andreas fault slips at low shear stress (≈15 MPa). Although the maximum stress on the fault is 15 MPa, models with an upper mantle shear zone deforming entirely by dislocation creep accumulate stresses that exceed 100 MPa, a stress level high enough to drive localized dynamic recrystallization and a shift in dominant deformation mechanism to diffusion creep. Models in which the mantle shear zone deform locally by diffusion creep reach a dynamic steady state where lithospheric shear stresses never exceed the specified fault stress anywhere in the model and indicate that the strength of the upper mantle is an important parameter in the dynamics of plate boundary deformation.
The topographic distribution of annual incoming solar radiation in the Rio Grande River Basin
Authors: Dubayah R. , van Katwijk V.
Published: February 2008

We model the annual incoming solar radiation topoclimatology for the Rio Grande River basin in Colorado, U.S.A. Hourly pyranometer measurements are combined with satellite reflectance data and 30 m digital elevation models within a topographic solar radiation algorithm. Our results show that there is large spatial variability within the basin, even at an annual integration length, but the annual, basin‐Wide mean is close to that measured by the pyranometers. The variance within 16 km2 and 100 km2 regions is a linear function of the average slope in the region, suggesting a possible parameterization for sub‐grid cell variability.
The geochemical model of Mars: An estimation from the high pressure experiments
Authors: Ohtani Eiji , Kamaya Noriko
Published: February 2008

Recent high pressure experiments on the model martian mantle provide firm constraints on the internal structure and chemistry of Mars. We examined the martian models proposed by Morgan and Anders (1979) and Dreibus and Wanke (1985) based on the mineral physics data obtained by the recent high pressure experiments. Original models proposed by these authors must be modified to reduce the mass fraction of the core and thus the bulk iron content of Mars in order to satisfy the geophysical constraints. We present a new model of the martian interior which satisfies the geophysical and cosmochemical constraints. Our model Mars is composed of a mixture of three components: 15.7% metal (M) component, 39.3% refractory silicate (R) component, and 45% volatile rich (V) component. The mass fraction of the core is 18.2 wt% and the bulk iron content is about 23 wt % in this model. The present analysis implies that the bulk iron content of Mars is significantly smaller than the iron contents of the other terrestrial planets and Chondrite. This suggests existence of some processes to fractionate iron and silicate in formation of the planets.
Comparison of weakly and strongly nonlinear wave evolution in a dispersive plasma
Authors: Vasquez Bernard J.
Published: February 2008

An investigation of the evolution of strongly nonlinear, low frequency (∼ion gyrofrequency), parallel propagating wave packets in a dispersive, collisionless, and low β(= 8πP/B2 = 0.3) plasma is undertaken using a hybrid numerical code. These strongly nonlinear wave packets have a transverse magnetic field strength, or wave amplitude, which is of order or greater than the field strength along the direction of propagation, and their evolution can differ qualitatively from that of weakly nonlinear packets. Strongly nonlinear, Alfven wave packets steepen but not from behind the maximum of wave amplitude as occurs during wave collapse. The development of spreading fast wave (right helicity) and rarefaction regions competes strongly with steepening, and leads to a long time waveform which differs greatly from that for weak nonlinearity. Results are used to suggest that strongly nonlinear wave evolution occurs frequently in the Earth's foreshock.
Actinometric measurement of j[O3‐O(1D)] using a luminol detector
Authors: Bairai Solomon T. , Stedman Donald H.
Published: February 2008

The photolysis frequency of ozone to singlet D oxygen atoms has been measured by means of a chemical actinometer using a luminol based detector. The instrument measures j[O3‐O(1D)] with a precision of 10%. The data collected in winter and spring of 1991 is in agreement with model predictions and previously measured values. Data from a global solar radiometer can be used to estimate the effects of local cloudiness on j[O3‐O(1D)].
No tectonic rotation for the Apulia‐Gargano Foreland in the Pleistocene
Authors: Scheepers Peter
Published: February 2008

In Apulia (southern Italy), 11 quarries in late Pliocene and early Pleistocene clays were sampled to study the rotation of the underlying Apulian Unit. To analyze the Natural Remanent Magnetization (NRM) of the samples thermal magnetization was performed. Several NRM‐components were distinguished. The component removed between 350–380°C and 450–480°C is the most consistent one; it also shows a positive reversal test. There is no rotation for this so‐called HT‐component. Mean inclination is the same as the inclination of the geocentric axial dipole (GAD) field for the present latitude of the area. It is concluded that these young clays reflect the geomagnetic field quite clear and that this part of the Adriatic microplate did not have any tectonic rotations since the Pleistocene.
Mössbauer Spectroscopy of Mg0.9Fe0.1 SiO3 perovskite
Authors: Jeanloz Raymond , O'Neill Bridget , Pasternak Moshe P. , Taylor R. Dean , Bohlen Steven R.
Published: February 2008

Ambient pressure Mössbauer spectra of Mg0.957Fe0.1SiO3 perovskite synthesized at pressure‐temperature conditions of ∼50 GPa and 1700 K show that the iron is entirely high‐spin Fe2+ and appears to be primarily located in the octahedral site within the crystal structure. We observe broad Mössbauer lines, suggesting a distribution of electric‐field gradients caused by disorder associated with the Fe ions. Also, the perovskite exhibits magnetic ordering at temperatures < 5 K, implying that there is a magnetic contribution to the absolute (“third‐law”) entropy of this phase.
Effect of velocity structure in D″ on PKP phases
Authors: Song Xiaodong , Helmberger Don V.
Published: February 2008

Differential travel times between various branches of PKP are used to study the P velocity structure in D″. Simple geometrical ray tests show that the ray path of the AB branch, which almost grazes the core‐mantle boundary (CMB), is much more sensitive to the velocity structure in D″ than the DF and BC branches, which have small incident angles at the CMB. Thus, the differential travel times of AB and DF and AB and BC provide an effective means of studying lateral variations in D″. In a systematic search of six years of the GDSN short period data on CD‐ROM, large anomalies in differential travel times of AB ‐ DF and AB ‐ BC were observed for different regions of D″. The scatter of BC ‐ DF data is half the scatter of AB ‐ DF and AB ‐ BC data, suggesting that the lowermost mantle has more influence on AB ‐ DF and AB ‐ BC data than the bottom of the outer core or the top of the inner core. The mean of the AB ‐ DF data set shows a 1 s offset relative to Preliminary Reference Earth Model (PREM) [Dziewonski and Anderson, 1981], in that (AB ‐ DF)prem is smaller than (AB ‐ DF)obs. Variations of the lower mantle PREM model that contain a discontinuity or a more distributed 1.5% velocity reduction in the lower 500 km can explain the discrepancy. The largest variations in the AB ‐ DF data are associated with paths sampling beneath the mid‐Pacific. The AB ‐ DF data along the mid‐Pacific paths are about 1.0 s smaller than the average of the AB ‐ DF from other paths and the differences are as large as 2.0 s at some distances.
Winter warming from large volcanic eruptions
Authors: Robock Alan , Mao Jianping
Published: February 2008

An examination of the Northern Hemisphere winter surface temperature patterns after the 12 largest volcanic eruptions from 1883–1992 shows warming over Eurasia and North America and cooling over the Middle East which are significant at the 95% level. This pattern is found in the first winter after tropical eruptions, in the first or second winter after midlatitude eruptions, and in the second winter after high latitude eruptions. The effects are independent of the hemisphere of the volcanoes. An enhanced zonal wind driven by heating of the tropical stratosphere by the volcanic aerosols is responsible for the regions of warming, while the cooling is caused by blocking of incoming sunlight.