An experimental study of Hapke’s modeling of natural granular surface samples     

A.L. Souchon  P.C. Pinet  S.D. Chevrel  Y.H. Daydou  D. Baratoux  K. Kurita  P. Helfenstein 《Icarus》2011,215(1):313-243

A series of natural granular surfaces composed of volcanic samples that widely vary in grain sizes (from the micron-scale to the millimeter-scale), shapes, surface aspects, origins, and including glass and minerals, has been measured in the visible domain with the spectro-imaging device ISEP (Observatoire Midi-Pyrénées, Toulouse, France) and inverted by photometric modeling. The experimental protocol makes use of a specific set of multiangular configurations (on the order of a few tens) with sufficient angular diversity and coverage of the bidirectional space to resolve differences in particle phase function behavior and surface texture. This restrained set delivers comparable results in terms of photometric parameters to those produced with a dense set of hundreds of measurements. The considered samples in this work have been chosen to assess the influence of varied physical properties on light scattering behavior. The following specific photometric trends are found. Samples comprising fresh glass or monocrystals in a proportion on the order of 30% or more (from binocular magnifying glass inspection) are extremely forward scattering with narrow scattering lobes, and the larger the particles, the narrower the scattering lobe; also, round particles tend to be more backscattering than irregularly-shaped ones of similar texture, and the presence of voids within particles tends to increase the backscattering character of the sample. Particles with broad scattering lobes (phase function asymmetry parameter b ? 0.5) display relatively large modeled surface macroscopic roughness values (15-25°), while particles with narrow scattering lobes (b ? 0.5) show smaller modeled surface macroscopic roughness (between 15° and ∼3°).The comparison between the present results for the scattering parameters b and c, and those obtained in previous studies from artificial particles shows a similar trend and general agreement although some discrepancies were observed. The granular surface samples analyzed in the present study that contain a high proportion of isolated translucent monocrystals and/or fresh glass appear extremely forward-scattering and clearly chart a new part of the c vs. b trend. This is further supported by recent similar findings for martian in situ data and lunar regolith simulants. These results should help to better interpret present and future orbital and landed photometric data from bodies’ surfaces such as the Moon’s, Mars’, Vesta’s or Mercury’s regolith.  相似文献   

Distribution and time-variation of spire streaks at Pavonis Mons on Mars     

T. Toyota  K. Kurita 《Planetary and Space Science》2011,59(8):672-682

We documented the distribution and the time-variation of the specific dark wind streaks at Pavonis Mons. We focused on the streaks we named “Spire Streaks”, which are overlapping spindle shaped dark streaks at the upper boundary of the coalesced dark streaks on Tharsis volcanoes. We investigated both visible and infrared images obtained by Viking orbiter camera, Mars Orbiter Camera (MOC), THEMIS, CTX and HiRISE of the spire streaks at Pavonis Mons. We also used topographic data obtained by Mars Orbiter Laser Altimeter (MOLA) to see the relationship between the topography and the distribution of the spire streaks. The spire streaks at Pavonis Mons provide us high-resolution information about the direction of the nighttime slope wind, and could be indirect clues for the time-variation of the nighttime environment. We conclude that the spire streaks are erosional features. However, some features of the spire streaks reported in this paper are outside the scope of previous modeling for erosional process, and we need a new category of model for the formation.  相似文献   

http://www.sciencedirect.com/science/article/pii/S1674987112001028     

Tatsuyuki Yamamoto  Hideo Akiyoshi  Keisuke Yoshikiyo  Tetsuya Takahashi  Yukiko Tanabe  Sakae Kudoh  Satoshi Imura  Naoyuki Yamamoto 《地学前缘(英文版)》2013,4(6):647-653

A study on the effect of the solar ultra-violet radiation on the human skin fibroblast cells revealed that the production of matrix metalloproteinase-2 was inhibited by the radiation.A CO2 incubator connected by optical fibers to a reflector telescope for collecting the solar light was built at Syowa station by the 49th Japanese Antarctica Research Expedition.The direction of the telescope was continuously controlled by a sun-tracker to follow the movement of the Sun automatically.The intensity of the collected light was monitored by a portable spectrophotometer housed inside.The human skin fibroblast cells were incubated in the CO2 chamber to investigate the effect of the solar radiation at Syowa station and were compared with those reference experiments at a laboratory in Japan.The results showed cell damage by strong UV radiation.The production of matrix metalloproteinase-2 was prompted by the moderate UV-B,but was inhibited by the strong UV-B radiation,as studied under laboratory conditions in Japan.The effect of strong solar radiation at Syowa station involving the radiation of UV-B region was estimated to be of the same extent of the radiation caused by an artificial UV-B light with the intensity more than 50 mJ/cm2.  相似文献   

Neutron absorption constraints on the composition of 4 Vesta     

Thomas H. Prettyman  David W. Mittlefehldt  Naoyuki Yamashita  Andrew W. Beck  William C. Feldman  John S. Hendricks  David J. Lawrence  Timothy J. McCoy  Harry Y. McSween  Patrick N. Peplowski  Robert C. Reedy  Michael J. Toplis  Lucille Le Corre  Hugau Mizzon  Vishnu Reddy  Timothy N. Titus  Carol A. Raymond  Christopher T. Russell 《Meteoritics & planetary science》2013,48(11):2211-2236

Global maps of the macroscopic thermal neutron absorption cross section of Vesta's regolith by the Gamma Ray and Neutron Detector (GRaND) on board the NASA Dawn spacecraft provide constraints on the abundance and distribution of Fe, Ca, Al, Mg, and other rock‐forming elements. From a circular, polar low‐altitude mapping orbit, GRaND sampled the regolith to decimeter depths with a spatial resolution of about 300 km. At this spatial scale, the variation in neutron absorption is about seven times lower than that of the Moon. The observed variation is consistent with the range of absorption for howardite whole‐rock compositions, which further supports the connection between Vesta and the howardite, eucrite, and diogenite meteorites. We find a strong correlation between neutron absorption and the percentage of eucritic materials in howardites and polymict breccias, which enables petrologic mapping of Vesta's surface. The distribution of basaltic eucrite and diogenite determined from neutron absorption measurements is qualitatively similar to that indicated by visible and near infrared spectroscopy. The Rheasilvia basin and ejecta blanket has relatively low absorption, consistent with Mg‐rich orthopyroxene. Based on a combination of Fe and neutron absorption measurements, olivine‐rich lithologies are not detected on the spatial scales sampled by GRaND. The sensitivity of GRaND to the presence of mantle material is described and implications for the absence of an olivine signature are discussed. High absorption values found in Vesta's “dark” hemisphere, where exogenic hydrogen has accumulated, indicate that this region is richer in basaltic eucrite, representative of Vesta's ancient upper crust.  相似文献   

The potential of intra-regional supply and demand of agricultural products in an urban fringe area: A case study of the Kanto Plain,Japan     

Hideharu Kurita  Makoto Yokohari  Jay Bolthouse 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(2):147-159

Geografisk Tidsskrift—Danish Journal of Geography 109(2):147–159, 2009

The increasingly global reach of industrial agricultural production has progressively distanced consumers and producers. Not surprisingly, opposition to the global food system commonly seeks to re-localize agriculture by cutting the distance between agricultural production and consumption. Analysis of potential foodsheds can provide an important basis upon which to recover local systems of production and consumption. Here, we examine the potential for municipal and micro-level foodsheds in the greater Tokyo mega-region. Similar to other large cities in Asia, the urban fringe of Tokyo has extensive areas of mixed urban and agricultural land-uses which are often seen as problematic, but which may have many merits from the standpoint of sustainable foodsheds. Indeed, our results indicate that many areas on the urban fringe of the Tokyo mega-region bear potential to meet demand for both rice and vegetables within their borders. Moreover, many people could meet their food needs within a short distance of their residence. These results demonstrate the need to examine the potential for micro-level foodsheds on the urban fringe.  相似文献   

Interpretation of El Niño–Southern Oscillation‐related precipitation anomalies in north‐western Borneo using isotopic tracers          下载免费PDF全文

Naoyuki Kurita  Mayumi Horikawa  Hironari Kanamori  Hatsuki Fujinami  Tomo'omi Kumagai  Tetsuzo Yasunari 《水文研究》2018,32(14):2176-2186

We examined rainfall anomalies associated with the El Niño–Southern Oscillation (ENSO) in northern Sarawak, Malaysia, using the oxygen isotopic composition of rainfall. Two precipitation‐sampling campaigns were conducted for isotope analysis: (a) at the Lambir Hill National Park (4.2° N, 114.0° E) from July 2004 to October 2006 and (b) at the Gunung Mulu National Park (3.9° N, 114.8° E) from January 2006 to July 2008. The records from these campaigns were merged with a previously published rainfall isotope dataset from Gunung Mulu site to create a 7‐year‐long record of the oxygen isotopic composition of Sarawak rainfall. The record exhibits clear intraseasonal variations (ISVs) with periods ranging from 10 to 70 days. The ISVs of 10‐ to 90‐day band‐pass filtered oxygen isotopic composition are linked to the synoptic‐scale precipitation anomalies over the southern South China Sea (SCS). The lead–lag correlation map of precipitation with the filtered oxygen isotope anomalies shows that an anomalous wet condition responsible for the decrease in oxygen isotopic composition appears over the SCS in association with the passage of north‐eastward propagation of the boreal summer intraseasonal oscillation (BSISO) in the summer monsoon season. The anomalous wet condition in spring is connected with eastward‐propagating Madden–Julian oscillation (MJO), whereas the sustained wet condition in winter is responsible for the occurrence of the Borneo vortex (BV) over the SCS. ENSO modulates the frequency of these synoptic conditions on a seasonal and longer time scale, showing a strong correlation between the seasonal isotopic anomalies and the Southern Oscillation index. We therefore discern, from the significant correlation between the isotope anomalies and area‐averaged Sarawak rainfall anomalies (R = ?0.65, p < 0.01), that ENSO‐related precipitation anomalies are linked to the seasonal modulation of the BSISO and MJO activity and BV genesis.  相似文献   

The volcanic history of central Elysium Planitia: Implications for martian magmatism     

J. Vaucher  N. Mangold  K. Kurita 《Icarus》2009,204(2):418-151

Central Elysium Planitia (CEP) is located south of Elysium Mons. Back to the era of the Viking orbiters, clues accumulated in favor of recent volcanism in relation with ground water release and the formation of long sub-parallel fissures. Four aqueous flood channel systems emanate from linear fissures. Recent eruptions of low viscosity lavas originate from these fissures and from low shield volcanoes. The objective of this paper is to constrain the volcanic history of this region, and to determine the chronological relationships with fluvial/erosional processes. New observations (e.g., new shield volcanoes and one new fluvial event) are summarized on a context map. Thirty-five surfaces have been dated from the count of about 15,000 impact craters. Ages have been cross-checked with relative stratigraphy when possible. A probabilistic approach has been introduced to compare similar ages and define periods of volcanic activity. Our results confirm that some volcanic features are extremely recent (∼2 My). Active periods are found at 2.5-3 My, 4.3 My, 13.5-16.2 My, 19 My, 21-32 My, 58 My, 71 My, 85-95 My, 134 My, 173 My and 234 My, not excluding the possibility that some of the gaps would be filled with additional crater counts. The volcanic activity thus extended for at least the last 250 My. The lava volumes have been estimated from the topographic modeling of the floor of depressions filled up by volcanic products, including the volumes of several large crater cavities buried under lavas (>20% of the total volume). Our new estimation of the total lava volume is 1.5 ± 0.2 × 10⁵ km³. This value corresponds to an average thickness of one hundred meters of lavas for the young volcanic plain. As a consequence, the total eruption rate at CEP, defined as the total volume of lava divided by the time of emplacement 1.4 × 10⁻²-1.8 × 10⁻² m³/s is lower than values typically estimated for terrestrial hot spots or large igneous provinces, suggesting longer inactive periods. The concept of mantle plumes responsible for terrestrial flood volcanism may not be applicable to the case of CEP and the mechanism proposed in Schumacher and Dreuer (2007) offers a plausible alternative to explain our observations.  相似文献   

Thermophysical properties of lunar material returned by Apollo missions     

Ki-Iti Horai  Naoyuki Fujii 《Earth, Moon, and Planets》1972,4(3-4):447-475

Data on thermophysical properties measured on lunar material returned by Apollo missions are reviewed. In particular, the effects of temperature and interstitial gaseous pressure on thermal conductivity and diffusivity have been studied. For crystalline rocks, breccias and fines, the thermal conductivity and diffusivity decrease as the interstitial gaseous pressure decreases from 1 atm to 10^–4T. Below 10^–4T, these properties become insensitive to the pressure. At a pressure of 10^–4T or below, the thermal conductivity of fines is more temperature dependent than that of crystalline rocks and breccias. The bulk density also affects the thermal conductivity of the fines. An empirical relationship between thermal conductivity, bulk density and temperature derived from the study of terrestrial material is shown to be consistent with the data on lunar samples. Measurement of specific heat shows that, regardless of the differences in mineral composition, crystalline rocks and fines have almost identical specific heat in the temperature range between 100 and 340K. The thermal parameter calculated from thermal conductivity, density and specific heat shows that the thermal properties estimated by earth-based observations are those characteristic only of lunar fines and not of crystalline rocks and breccias. The rate of radioactive heat generation calculated from the content of K, Th and U in lunar samples indicates that the surface layer of the lunar highland is more heat-producing than the lunar maria. This may suggest fundamental differences between the two regions.Now at Lamont-Doherty Geological Observatory, Columbia University, Palisades, New York, U.S.A.  相似文献   

On the spiral structure in the galactic distribution of co clouds     

Takeyasu Sawa  Tatsuya Kurita  Akira Sobue  Yutaka Sabano 《Astrophysics and Space Science》1983,92(1):181-190

The CO distribution in the Galaxy is investigated through an analysis of longitude-velocity diagrams of CO emission lines for the two longitude ranges 20°<l<80° and 105°<l<140°. For the kinematics of the Galaxy we adopt the three typical models; the circular rotation, the linear density waves, and the galactic shock waves. It is shown that the distributions and kinematics of CO clouds are consistent with the predictions of the density wave model and the galactic shock model, and that the observed data of CO emissions do not contradict with the claim that the CO clouds form spiral arms.  相似文献   

A Numerical Study of Turbulence Statistics and the Structure of a Spatially-Developing Boundary Layer Over a Realistic Urban Geometry     

Atsushi Inagaki  Manabu Kanda  Nurul Huda Ahmad  Ayako Yagi  Naoyuki Onodera  Takayuki Aoki 《Boundary-Layer Meteorology》2017,163(2):161-177

Sonic anemometer measurements are analyzed from two primary field programs and 12 supplementary sites to examine the behaviour of the turbulent heat flux near the surface with high wind speeds in the nocturnal boundary layer. On average, large downward heat flux is found for high wind speeds for most of the sites where some stratification is maintained in spite of relatively intense vertical mixing. The stratification for high wind speeds is found to be dependent on wind direction, suggesting the importance of warm-air advection, even for locally homogenous sites. Warm-air advection is also inferred from a large imbalance of the heat budget of the air for strong winds. Shortcomings of our study are noted.  相似文献