The frequency of meteorite falls: Comments on two conflicting solutions to the problem

Abstract— Recent estimates of the current rate of meteorite falls have been derived from camera network observations and from the statistics of the recovery of small fragments in Roosevelt County, New Mexico. The results are discordant. The integrated sky coverage for the camera data is an order of magnitude greater than the long exposure over small areas in New Mexico, yet the number of inferred events is comparable. We examine potential problems and find no effects other than random ones to bias the camera data. New data on the total number of suitable fireballs indicate that the flux from the camera network is already close to the upper limit imposed by the count of over 700 fireballs. By contrast, the calibration of the decay time for small fragments in New Mexico appears insecure and could account for a factor-of-three discrepancy. The large area of a typical strewn field relative to the small search areas is also a serious problem that remains uncalibrated. There are problems with the application of either the camera results or the New Mexico data to the statistics of recoveries in Antarctica since the Antarctic search areas are not free from the strewn-field problem. Since there is no evidence for a substantial change in the infall rate in intervals less than the ages of the collecting surfaces, we believe the camera network flux data remain the best estimate for the arrival rate of small meteorites on Earth.     

EFFECT OF ANTHROPOGENIC CO_2 ON THE pH AND THE SATURATION STATES OF CALCITE AND ARAGONITE OF SEAWATER

unODUcrIONIntereStinthecarboncycehasinamsedbouseoftheobservedincreaseinatmosphericCO,leveIsduetothebumingoffossilfuelandthedearingofforestsre-sultinginlargedhaticandbiogeochdrica1consequenas(ChenandDrake,l986).Experi-mentalstudisofp1antShaveshownresponsesoftypically2O%-4O%highergroWthunderdoubledCo,conditions.Ontheotherhand,theeffedofelevatalCO=conditionsinincreasinggroWth,knownastheCO,fertilimtioneffed,isnotbe1ievedtobetwortantintheoasns(Schimeletal.,1995).Althoughithasbeensuggestedt…     

Effects of a clumpy circumstellar medium on the dynamics of stellar winds

Mass pickup from clumps resulting from previous mass loss phases by a fast stellar wind can substantially modify its behaviour, even leading to a highly supersonic wind becoming transonic before leaving the mass-loading region. The observational consequences of mass-loading on these astrophysical flows is discussed.     

An Evaluation of Tsunami Forecasts from the T2 Scenario Database

A tsunami scenario database (T2) has recently been developed for use within the Joint Australian Tsunami Warning Centre (JATWC). This scenario database has proven to be a very useful tool for forecast guidance, issuing of tsunami warnings and general event analysis. In this paper, the T2 scenarios are described, and evaluated by comparing them with observations of sea level from tsunameters for a number of recent tsunami events. In general, the T2 scenario database performs very well in terms of predicting the arrival time of the tsunami and the wave amplitudes at tsunameter locations.     

Parameterization of bedform morphology and defect density with fingerprint analysis techniques

A novel method for parameterizing the morphology of seafloor ripples with fingerprint analysis numerical techniques is presented. This fully automated analysis tool identifies rippled areas in two-dimensional imagery of the seafloor, and returns ripple orientation and wavelength as well as a new morphological parameter, the spatial density of ripple defects. In contrast to widely used manual and spectral parameterization methods, this new technique yields a unique probability distribution for each derived parameter, which describes its spatial variability across the sampled domain. Here we apply this new analysis technique to synthetic and field collected side-scan sonar seafloor images in order to assess the methods capacity to define bed geometry across a wide range of simulated and observed morphological conditions. The resulting orientation and wavelength values compare favorably with those of the existing manual and spectral parameterization methods, and are superior under environmental conditions characterized by low signal to noise ratios as well as high planform ripple sinuosity. Furthermore, the resulting ripple defect density values demonstrate correlation with ripple orientation, wave direction, and the Shields parameter, which is consistent with recent investigations that have theoretically linked this parameter to hydrodynamic forcing conditions. The presented fingerprint analysis method surpasses the capacity of existing methods for ripple parameterization and promises to yield greater insight into theoretical and applied problems associated with the temporal and spatial variability of ripple morphology across a wide spectrum of marine environments.     

Long-term trends in benthic habitat quality as determined by Multivariate AMBI and Infaunal Quality Index in relation to natural variability: a case study in Kinsale Harbour, south coast of Ireland

Benthic Ecological Quality Ratios (EQR) are important tools for assessing the ecological status of coastal and transitional water bodies. Here, we use spatial and time-series data from Kinsale Harbour, Ireland to examine the effects of sample processing methodologies on the outputs of two EQRs: Multivariate AMBI (M-AMBI) and Infaunal Quality Index (IQI).Both EQRs were robust to changes in sieve size from 1 mm to 0.5 mm, and to changes in the taxa identified in spatial calibration. Both EQRs classified habitat quality in Kinsale as generally Good or High with no evidence of significant change over the time series (1981-2006). IQI classified the ecological status as higher than M-AMBI.There was a significant relationship between IQI and M-AMBI in spatial calibration, but no significant relationship between them in time series. Further research into the behaviour of EQRs in relation to natural variability over long time-scales is needed to discriminate anthropogenic impacts reliably.     

THE L5 BAYARD METEORITE: A 1982 FIND

The Bayard chondrite, found in western Nebraska in 1982, is a single mass of 75 kg. Composition of olivine (Fa 24.5) and orthopyroxene (Fs 22.0), along with bulk composition, support an L-classification. The presence of equilibrated and partially recrystallized minerals indicate petrologic type 5 classification.     

Quaternary eolian dunes in the Savannah River valley,Jasper County,South Carolina,USA

Sand hills in the Savannah River valley in Jasper County (South Carolina, USA) are interpreted as the remnants of parabolic eolian dunes composed of sand derived from the Savannah River and stabilized by vegetation under prevailing climate conditions. Optically stimulated luminescence ages reveal that most of the dunes were active ca. 40 to 19 ka ago, coincident with the last glacial maximum (LGM) through early deglaciation. Modern surface winds are not sufficient for sustained eolian sand transport. When the dunes were active, winds blew at velocities of at least 4 m/s from west to east, and some vegetation was present. The ratio of annual precipitation to potential evapotranspiration (P:PE) was less than the modern ratio of 1.23 and may have been < 0.30, caused by stronger winds (which would have resulted in greater evaporation) and/or reduced precipitation. The Savannah River dunes are part of a larger assemblage of eolian dunes that were active in the eastern United States during and immediately after the LGM, suggesting that eolian sediment behavior in this region has been controlled by regional forcing mechanisms during the Quaternary.     

http://www.sciencedirect.com/science/article/pii/S1674987113000327

The Panzhihua intrusion in southwest China is part of the Emeishan large igneous province and host of a large Fe-Ti-V ore deposit.In previous interpretations it was considered to be a layered,differentiated sill with the ore deposits at its base.New structural and petrological data suggest instead that the intrusion has an open S-shape,with two near-concordant segments joined by a discordant dyke-like segment. During emplacement of the main intrusion,multiple generations of mafic dykes invaded carbonate wall rocks,producing a large contact aureole.In the central segment,magmatic layering is oriented oblique to the walls of the intrusion.This layering cannot have formed by crystal settling or in-situ growth on the floor of the intrusion;instead we propose that it resulted from inward solidification of multiple,individually operating,convection cells.Ore formation was triggered by interaction of magma with carbonate wall rocks.