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排序方式: 共有125条查询结果,搜索用时 109 毫秒
101.
Sandrine Bony Bjorn Stevens Felix Ament Sebastien Bigorre Patrick Chazette Susanne Crewell Julien Delanoë Kerry Emanuel David Farrell Cyrille Flamant Silke Gross Lutz Hirsch Johannes Karstensen Bernhard Mayer Louise Nuijens James H. RuppertJr. Irina Sandu Pier Siebesma Sabrina Speich Frédéric Szczap Julien Totems Raphaela Vogel Manfred Wendisch Martin Wirth 《Surveys in Geophysics》2017,38(6):1529-1568
Trade-wind cumuli constitute the cloud type with the highest frequency of occurrence on Earth, and it has been shown that their sensitivity to changing environmental conditions will critically influence the magnitude and pace of future global warming. Research over the last decade has pointed out the importance of the interplay between clouds, convection and circulation in controling this sensitivity. Numerical models represent this interplay in diverse ways, which translates into different responses of trade-cumuli to climate perturbations. Climate models predict that the area covered by shallow cumuli at cloud base is very sensitive to changes in environmental conditions, while process models suggest the opposite. To understand and resolve this contradiction, we propose to organize a field campaign aimed at quantifying the physical properties of trade-cumuli (e.g., cloud fraction and water content) as a function of the large-scale environment. Beyond a better understanding of clouds-circulation coupling processes, the campaign will provide a reference data set that may be used as a benchmark for advancing the modelling and the satellite remote sensing of clouds and circulation. It will also be an opportunity for complementary investigations such as evaluating model convective parameterizations or studying the role of ocean mesoscale eddies in air–sea interactions and convective organization. 相似文献
102.
103.
Arya Udry Zoë E. Wilbur Rachel R. Rahib Francis M. McCubbin Kathleen E. Vander Kaaden Timothy J. McCoy Karen Ziegler Juliane Gross Christopher DeFelice Logan Combs Brent D. Turrin 《Meteoritics & planetary science》2019,54(4):785-810
We present petrologic and isotopic data on Northwest Africa (NWA) 4799, NWA 7809, NWA 7214, and NWA 11071 meteorites, which were previously classified as aubrites. These four meteorites contain between 31 and 56 vol% of equigranular, nearly endmember enstatite, Fe,Ni metal, plagioclase, terrestrial alteration products, and sulfides, such as troilite, niningerite, daubréelite, oldhamite, and caswellsilverite. The equigranular texture of the enstatite and the presence of the metal surrounding enstatite indicate that these rocks were not formed through igneous processes like the aubrites, but rather by impact processes. In addition, the presence of pre‐terrestrially weathered metal (7.1–14 vol%), undifferentiated modal abundances compared to enstatite chondrites, presence of graphite, absence of diopside and forsterite, low Ti in troilite, and high Si in Fe,Ni metals suggest that these rocks formed through impact melting on chondritic and not aubritic parent bodies. Formation of these meteorites on a parent body with similar properties to the EHa enstatite chondrite parent body is suggested by their mineralogy. These parent bodies have undergone impact events from at least 4.5 Ga (NWA 11071) until at least 4.2 Ga (NWA 4799) according to 39Ar‐40Ar ages, indicating that this region of the solar system was heavily bombarded early in its history. By comparing NWA enstatite chondrite impact melts to Mercury, we infer that they represent imperfect petrological analogs to this planet given their high metal abundances, but they could represent important geochemical analogs for the behavior and geochemical affinities of elements on Mercury. Furthermore, the enstatite chondrite impact melts represent an important petrological analog for understanding high‐temperature processes and impact processes on Mercury, due to their similar mineralogies, Fe‐metal‐rich and FeO‐poor silicate abundances, and low oxygen fugacity. 相似文献
104.
A grain of light‐blue sulfate material was reported in the lunar highlands regolith meteorite PCA 02007 (Satterwhite and Righter 2013). Allocated grains of that material are, in fact, aluminosilicate glass with a chemical composition like that of the bulk meteorite and other lunar highlands regoliths. The calcium sulfate detected in PCA 02007 was likely a surface coating, and reasonably of Antarctic (not lunar) origin. 相似文献
105.
G. Le Petit G. Douysset G. Ducros P. Gross P. Achim M. Monfort P. Raymond Y. Pontillon C. Jutier X. Blanchard T. Taffary C. Moulin 《Pure and Applied Geophysics》2014,171(3-5):629-644
Part I of this publication deals with the analysis of fission product releases consecutive to the Fukushima Dai-ichi accident. Reactor core damages are assessed relying on radionuclide detections performed by the CTBTO radionuclide network, especially at the particulate station located at Takasaki, 210 km away from the nuclear power plant. On the basis of a comparison between the reactor core inventory at the time of reactor shutdowns and the fission product activities measured in air at Takasaki, especially 95Nb and 103Ru, it was possible to show that the reactor cores were exposed to high temperature for a prolonged time. This diagnosis was confirmed by the presence of 113Sn in air at Takasaki. The 133Xe assessed release at the time of reactor shutdown (8 × 1018 Bq) turned out to be in the order of 80 % of the amount deduced from the reactor core inventories. This strongly suggests a broad meltdown of reactor cores. 相似文献
106.
107.
Kaushik Sasmal Eiji Masunaga Adrean Webb Oliver B. Fringer Edward S. Gross Matthew D. Rayson Hidekatsu Yamazaki 《Journal of Oceanography》2018,74(2):169-186
The three-dimensional numerical model SUNTANS is applied to investigate river plume mixing in Otsuchi Bay, an estuary located along the Sanriku Coast of Iwate, Japan. Results from numerical simulations with different idealized forcing scenarios (barotropic tide, baroclinic tide, and diurnal wind) are compared with field observations to diagnose dominant mixing mechanisms. Under the influence of combined barotropic, baroclinic and wind forcing, the model reproduces observed salinity profiles well and achieves a skill score of 0.94. In addition, the model forced by baroclinic internal tides reproduces observed cold-water intrusions in the bay, and barotropic tidal forcing reproduces observed salt wedge dynamics near the river mouths. Near these river mouths, vertically sheared flows are generated due to the interaction of river discharge and tidal elevations. River plume mixing is quantified using vertical salt flux and reveals that mixing near the vicinity of the river mouth, is primarily generated by the barotropic tidal forcing. A 10 ms?1 strong diurnal breeze compared to a 5 ms?1 weak breeze generates higher mixing in the bay. In contrast to the barotropic forcing, internal tidal (baroclinic) effects are the dominant mixing mechanisms away from the river mouths, particularly in the middle of the bay, where a narrow channel strengthens the flow speed. The mixing structure is horizontally asymmetric, with the middle and northern parts exhibiting stronger mixing than the southern part of the bay. This study identifies several mixing hot-spots within the bay and is of great importance for the coastal aquaculture system. 相似文献
108.
An improved empirical model for the effect of long-period ocean tides on polar motion 总被引:2,自引:1,他引:1
Richard S. Gross 《Journal of Geodesy》2009,83(7):635-644
Because the tide-raising potential is symmetric about the Earth’s polar axis it can excite polar motion only by acting upon
non-axisymmetric features of the Earth like the oceans. In fact, after removing atmospheric and non-tidal oceanic effects,
polar motion excitation observations show a strong fortnightly tidal signal that is not completely explained by existing dynamical
and empirical ocean tide models. So a new empirical model for the effect of the termensual (Mtm and mtm), fortnightly (Mf and mf), and monthly (Mm) tides on polar motion is derived here by fitting periodic terms at these tidal frequencies to polar motion excitation observations
that span 2 January 1980 to 8 September 2006 and from which atmospheric and non-tidal oceanic effects have been removed. While
this new empirical tide model can fully explain the observed fortnightly polar motion excitation signal during this time interval
it would still be desirable to have a model for the effect of long-period ocean tides on polar motion that is determined from
a dynamical ocean tide model and that is therefore independent of polar motion observations. 相似文献
109.
Wanja Wedekind Christian J. Gross Andreas Hoffmann Siegfried Siegesmund 《Environmental Earth Sciences》2018,77(21):735
Sandstones, clay in the form of bricks and laterite are the building materials used by the Khmer to construct the imposing and magnificent temples in Southeast Asia. Many of these monuments suffer from fracturing, sanding, contour scaling, crust formation and salt weathering. The affinity to weathering is closely connected to the type of material. Two sandstone types classified as feldspathic arenite and quartz arenite of Angkor as well as two arkosic sandstones from Thailand are described and investigated in this study. Important petrophysical properties determined for the different sandstones consist of hydric expansion, thermal expansion, pore radii distribution and ultrasonic velocity. Different investigations such as capillary water uptake, surface hardness, hygroscopic water sorption, and salt resistance tests were undertaken in the laboratory to characterize the various rock types. Observations and quantified damage mapping were done onsite at the Phnom Bakheng Temple. Contour scaling in the form of weathering crusts is one of the main deterioration features observable at the Angkor monuments. Comparisons are made between the building stone, the crust material from the Phnom Bakheng Temple and fresh stone material used for restoration. Significant differences in hydric and especially in thermal expansion of the crust and sandstone have been determined. The results seem to indicate that extensional processes occur, which can be considered a force for detachment (i.e., contour scaling, flaking). In an experimental trial, the hydric and thermal expansion of the weathering crust and the building stone was significantly reduced by using a weak acid for the crust and a swelling inhibitor for the original building stone. 相似文献
110.
Christopher Potter Steven Klooster Seth Hiatt Matthew Fladeland Vanessa Genovese Peggy Gross 《Climatic change》2007,80(3-4):323-336
Afforestation of marginal agricultural lands represents a promising option for carbon sequestration in terrestrial ecosystems.
An ecosystem carbon model was used to generate new national maps of annual net primary production (NPP), one each for continuous
land covers of ‘forest’, ‘crop’, and ‘rangeland’ over the entire U. S. continental area. Direct inputs of satellite “greenness”
data from the Advanced Very High Resolution Radiometer (AVHRR) sensor into the NASA-CASA carbon model at 8-km spatial resolution
were used to estimate spatial variability in monthly NPP and potential biomass accumulation rates in a uniquely detailed manner.
The model predictions of regrowth forest production lead to a conservative national projection of 0.3 Pg C as potential carbon
stored each year on relatively low-production crop or rangeland areas. On a regional level, the top five states for total
crop afforestation potential were: Texas, Minnesota, Iowa, Illinois, and Missouri, whereas the top five states for total rangeland
afforestation potential are: Texas, California, Montana, New Mexico, and Colorado. Afforestation at this level of intensity
has the capacity to offset at least one-fifth of annual fossil fuel emission of carbon in the United States. These projected
afforestation carbon gains also match or exceed recent estimates of the annual sink for atmospheric CO2 in currently forested area of the country. 相似文献