Observations of a curving molecular outflow from V380 Ori-NE: further support for prompt entrainment in protostellar outflows     

C. J. Davis  W. R. F. Dent  H. E. Matthews  I. M. Coulson  M. J. McCaughrean 《Monthly notices of the Royal Astronomical Society》2000,318(3):952-960

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Holocene colluvial chronology in a sub‐arctic esker landscape at Kuttanen,Finnish Lapland: kettleholes as geo‐ecological archives of interactions amongst fire,vegetation, soil,climate and geomorphological instability          下载免费PDF全文

John A. Matthews  Matti Seppälä 《Boreas: An International Journal of Quaternary Research》2015,44(2):343-367

Excavations were made in the colluvial deposits of seven kettleholes in a sandy esker at Kuttanen, northwestern Finnish Lapland. The Holocene history of forest fires and the associated colluvial activity initiated on the slopes of the kettleholes were reconstructed based on 131 radiocarbon dates from charcoal layers. These dates were supplemented by luminescence dating of colluvial sand layers. The first forest fires occurred ～9000 years ago following the immigration of Pinus sylvestris about 1000 years after deglaciation. Evidence of forest fires and colluvial activity increased with the density of the pine forest, reaching a maximum during the Holocene Thermal Maximum between ～8000 and 4000 cal. a BP, declining thereafter to a minimum in the last ～500 years. This multimillennial‐scale pattern corresponds with forest fires being triggered by lightning strikes during the warmest summer weather of the Holocene, which also produced heavy rain and slope wash from convective storms. The 50 forest fires identified over the Holocene indicate a long cycle in fire frequency of 1 in ～200 years, which appears to reflect the average successional recovery time of the forest. Complex interactions amongst vegetation, fire and climate may account for little or no association between 23 centennial‐ to millennial‐scale clusters of forest fires/colluvial events and Holocene temperature or precipitation anomalies. Buried podzols indicate five phases of soil formation and hence low levels of landscape disturbance. The kettleholes and their colluvial deposits therefore provide a unique geo‐ecological archive that has led to new insights into the geo‐ecological interactions that affect environmental change in the sub‐arctic landscape.  相似文献   

A global assessment of the carbon cycle and temperature responses to major changes in future fire regime     

Jean-Sébastien Landry  H. Damon Matthews  Navin Ramankutty 《Climatic change》2015,133(2):179-192

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Contributions of individual countries?? emissions to climate change and their uncertainty   总被引：1，自引：0，他引：1  

Niklas H?hne  Helcio Blum  Jan Fuglestvedt  Ragnhild Bieltvedt Skeie  Atsushi Kurosawa  Guoquan Hu  Jason Lowe  Laila Gohar  Ben Matthews  Ana Claudia Nioac de Salles  Christian Ellermann 《Climatic change》2011,106(3):359-391

We have compiled historical greenhouse gas emissions and their uncertainties on country and sector level and assessed their contribution to cumulative emissions and to global average temperature increase in the past and for a the future emission scenario. We find that uncertainty in historical contribution estimates differs between countries due to different shares of greenhouse gases and time development of emissions. Although historical emissions in the distant past are very uncertain, their influence on countries?? or sectors?? contributions to temperature increase is relatively small in most cases, because these results are dominated by recent (high) emissions. For relative contributions to cumulative emissions and temperature rise, the uncertainty introduced by unknown historical emissions is larger than the uncertainty introduced by the use of different climate models. The choice of different parameters in the calculation of relative contributions is most relevant for countries that are different from the world average in greenhouse gas mix and timing of emissions. The choice of the indicator (cumulative GWP weighted emissions or temperature increase) is very important for a few countries (altering contributions up to a factor of 2) and could be considered small for most countries (in the order of 10%). The choice of the year, from which to start accounting for emissions (e.g. 1750 or 1990), is important for many countries, up to a factor of 2.2 and on average of around 1.3. Including or excluding land-use change and forestry or non-CO₂ gases changes relative contributions dramatically for a third of the countries (by a factor of 5 to a factor of 90). Industrialised countries started to increase CO₂ emissions from energy use much earlier. Developing countries?? emissions from land-use change and forestry as well as of CH₄ and N₂O were substantial before their emissions from energy use.  相似文献   

An Investigation of the CME of 3 November 2011 and Its Associated Widespread Solar Energetic Particle Event     

A. J. Prise  L. K. Harra  S. A. Matthews  D. M. Long  A. D. Aylward 《Solar physics》2014,289(5):1731-1744

Multi-spacecraft observations are used to study the in-situ effects of a large coronal mass ejection (CME) erupting from the farside of the Sun on 3 November 2011, with particular emphasis on the associated solar energetic particle (SEP) event. At that time both Solar Terrestrial Relations Observatory (STEREO) spacecraft were located more than 90 degrees from Earth and could observe the CME eruption directly, with the CME visible on-disk from STEREO-B and off the limb from STEREO-A. Signatures of pressure variations in the corona such as deflected streamers were seen, indicating the presence of a coronal shock associated with this CME eruption. The evolution of the CME and an associated extreme-ultraviolet (EUV) wave were studied using EUV and coronagraph images. It was found that the lateral expansion of the CME low in the corona closely tracked the propagation of the EUV wave, with measured velocities of 240±19 km?s^?1 and 221±15 km?s^?1 for the CME and wave, respectively. Solar energetic particles were observed to arrive first at STEREO-A, followed by electrons at the Wind spacecraft at L₁, then STEREO-B, and finally protons arrived simultaneously at Wind and STEREO-B. By carrying out a velocity-dispersion analysis on the particles arriving at each location, it was found that energetic particles arriving at STEREO-A were released first and that the release of particles arriving at STEREO-B was delayed by about 50 minutes. Analysis of the expansion of the CME to a wider longitude range indicates that this delay is a result of the time taken for the CME edge to reach the footpoints of the magnetic-field lines connected to STEREO-B. The CME expansion is not seen to reach the magnetic footpoint of Wind at the time of solar-particle release for the particles detected here, suggesting that these particles may not be associated with this CME.  相似文献   

Measurements of total ozone: Intercomparison of data from a variety of instruments,June 1981     

Andrew Matthews  Pierre Marche 《Planetary and Space Science》1983,31(7):787-790

The total ozone data obtained over southern France from a variety of instruments during the Intercomparison Campaign of June 1981 are presented and intercompared. All the instruments intercompared produced a self-consistent data set in terms of the variations that occurred during the intercomparison period and a discussion of the differences in the absolute values measured is given.  相似文献   

The upper atmosphere of Uranus: A critical test of isotropic turbulence models     

Richard G. French  James L. Elliot  Bruno Sicardy  Philip Nicholson  Keith Matthews 《Icarus》1982,51(3):491-508

Observations of the 15 August 1980 Uranus occultation of KM 12, obtained from Cerro Tololo InterAmerican Observatory, European Southern Observatory, and Cerro Las Campanas Observatory, are used to compare the atmospheric structure at points separated by ～140 km along the planetary limb. The results reveal striking, but by no means perfect, correlation of the light curves, ruling out isotropic turbulence as the cause of the light curve spikes. The atmosphere is strongly layered, and any acceptable turbulence model must accommodate the axial ratios of $\text{?60}$ which are observed. The mean temperature of the atmosphere is 150 ± 15°K for the region near number density 10¹⁴ cm^?3. Derived temperature variations of vertical scale ～ 130km and amplitude ±5°K are in agreement for all stations, and correlated spikes correspond to low-amplitude temperature variations with a vertical scale of several kilometers.  相似文献   

Quantifying uncertainty and variable sensitivity within the US billion-dollar weather and climate disaster cost estimates   总被引：2，自引：2，他引：0  

Adam B. Smith  Jessica L. Matthews 《Natural Hazards》2015,77(3):1829-1851

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Properties of the 15 February 2011 Flare Seismic Sources     

S. Zharkov  L. M. Green  S. A. Matthews  V. V. Zharkova 《Solar physics》2013,284(2):315-327

The first near-side X-class flare of Solar Cycle 24 occurred in February 2011 (SOL2011-02-05T01:55) and produced a very strong seismic response in the photosphere. One sunquake was reported by Kosovichev (Astrophys. J. Lett. 734, L15, 2011), followed by the discovery of a second sunquake by Zharkov, Green, Matthews et al. (Astrophys. J. Lett. 741, L35, 2011). The flare had a two-ribbon structure and was associated with a flux-rope eruption and a halo coronal mass ejection (CME) as reported in the CACTus catalogue. Following the discovery of the second sunquake and the spatial association of both sources with the locations of the feet of the erupting flux rope (Zharkov, Green, Matthews et al., Astrophys. J. Lett. 741, L35, 2011), we present here a more detailed analysis of the observed photospheric changes in and around the seismic sources. These sunquakes are quite unusual, taking place early in the impulsive stage of the flare, with the seismic sources showing little hard X-ray (HXR) emission, and strongest X-ray emission sources located in the flare ribbons. We present a directional time–distance diagram computed for the second source, which clearly shows a ridge corresponding to the travelling acoustic-wave packet and find that the sunquake at the second source happened about 45 seconds to one minute earlier than the first source. Using acoustic holography we report different frequency responses of the two sources. We find strong downflows at both seismic locations and a supersonic horizontal motion at the second site of acoustic-wave excitation.  相似文献   

Delta Scuti stars in the Praesepe cluster observed by the MOST satellite     

M. Breger  M. Hareter  M. Endl  R. Kuschnig  W.W. Weiss  J.M. Matthews  D.B. Guenther  A.F.J. Moffat  J.F. Rowe  S.M. Rucinski  D. Sasselov 《Astronomische Nachrichten》2012,333(2):131-137

The Praesepe cluster contains a number of δ Sct and γ Dor pulsators. Asteroseismology of cluster stars is simplified by the common distance, age and stellar abundances. Since asteroseismology requires a large number of known frequencies, the small pulsation amplitudes of these stars require space satellite campaigns. The present study utilizes photometric MOST satellite measurements in order to determine the pulsation frequencies of two evolved (EP Cnc, BT Cnc) and two main‐sequence (BS Cnc, HD 73872) δ Sct stars in the Praesepe cluster. The frequency analysis of the 2008 and 2009 data detected up to 34 frequencies per star with most amplitudes in the submillimag range. In BS Cnc, two modes showed strong amplitude variability between 2008 and 2009. The frequencies ranged from 0.76 to 41.7 cd^–1. After considering the different evolutionary states and mean stellar densities of these four stars, the differences and large ranges in frequency remain (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献