Reply to B. Lehmann's discussion     

M. Boissavy-Vinau  G. Roger 《Mineralium Deposita》1981,16(2):332-334

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Spatial Variability of Turbulent Fluxes in the Roughness Sublayer of an Even-Aged Pine Forest   总被引：1，自引：1，他引：0  

Gabriel Katul  Cheng-I Hsieh  David Bowling  Kenneth Clark  Narasinha Shurpali  Andrew Turnipseed  John Albertson  Kevin Tu  Dave Hollinger  Bob Evans  Brian Offerle  Dean Anderson  David Ellsworth  Chris Vogel  Ram Oren 《Boundary-Layer Meteorology》1999,93(1):1-28

The spatial variability of turbulent flow statistics in the roughness sublayer (RSL) of a uniform even-aged 14 m (= h) tall loblolly pine forest was investigated experimentally. Using seven existing walkup towers at this stand, high frequency velocity, temperature, water vapour and carbon dioxide concentrations were measured at 15.5 m above the ground surface from October 6 to 10 in 1997. These seven towers were separated by at least 100m from each other. The objective of this study was to examine whether single tower turbulence statistics measurements represent the flow properties of RSL turbulence above a uniform even-aged managed loblolly pine forest as a best-case scenario for natural forested ecosystems. From the intensive space-time series measurements, it was demonstrated that standard deviations of longitudinal and vertical velocities (_u, _w) and temperature (_T) are more planar homogeneous than their vertical flux of momentum (u_* ²) and sensible heat (H) counterparts. Also, the measured H is more horizontally homogeneous when compared to fluxes of other scalar entities such as CO₂ and water vapour. While the spatial variability in fluxes was significant (>15 %), this unique data set confirmed that single tower measurements represent the canonical structure of single-point RSL turbulence statistics, especially flux-variance relationships. Implications to extending the moving-equilibrium hypothesis for RSL flows are discussed. The spatial variability in all RSL flow variables was not constant in time and varied strongly with spatially averaged friction velocity u_*, especially when u_* was small. It is shown that flow properties derived from two-point temporal statistics such as correlation functions are more sensitive to local variability in leaf area density when compared to single point flow statistics. Specifically, that the local relationship between the reciprocal of the vertical velocity integral time scale (I_w) and the arrival frequency of organized structures (/h) predicted from a mixing-layer theory exhibited dependence on the local leaf area index. The broader implications of these findings to the measurement and modelling of RSL flows are also discussed.  相似文献   

Multivariate statistical methods: Within-groups covariation : E. H. Bryant and W. R. Atchley, Editors. Dowden, Hutchison, and Ross, Stroudsburg, Pennsylvania, 436 pp., $26.00     

Roger Del Moral 《Quaternary Research》1976,6(4)

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New terrestrial heat flow measurements on the Nazca Plate     

Roger N. Anderson  Marcus G. Langseth  Victor Vacquier  Jean Francheteau 《Earth and Planetary Science Letters》1976,29(2):243-254

Sixty-seven new heat flow measurements on the Nazca Plate are reported, and the thermal regimes of three specific areas on the plate are examined. The Nazca Ridge is an aseismic ridge which may have been generated as an “island trail” from the Easter Island “hot spot” and/or may be a fossil transform fault. The Nazca Ridge has lower heat flow than the surrounding sea floor implying that the ridge might have low “effective” thermal conductivity causing heat to preferentially flow or refract to surrounding ocean crust which has higher conductivity, or, the low heat flow values may be caused by hydrothermal circulation on the ridge. The Carnegie Plateau is an elevated region south of the Carnegie Ridge on the northeastern Nazca Plate with high heat flow and shallow topography consistent with an age of less than 20 m.y. B.P. The central Nazca Plate is an area of highly variable heat flow which is possibly related to thin sediment and to rough regional topography.  相似文献   

Palaeozoic radiometric age provinces in the Andean basement,latitudes 25°–30°S     

Sandra L. McBride  Juan C. Caelles  Alan H. Clark  Edward Farrar 《Earth and Planetary Science Letters》1976,29(2):373-383

More than fifty new K-Ar age determinations are reported for mineral separates and whole-rock samples from igneous and metamorphic basement rocks of northwestern Argentina and contiguous Chile between 25° and 30°S. The age data define three thermal events, occurring in the late Ordovician-Silurian (400–450 m.y.), mid-Carboniferous (310–340 m.y.) and Permian (225–270 m.y.), and confirm deductions of previous workers that the crystalline basement rocks of the Pampean Ranges of northwestern Argentina are not of Precambrian age, but rather evolved predominantly during the Palaeozoic. The proposed radiometric age provinces and the inferred orogenic history of the area are compared with those for the rest of South America, and it is confirmed that, by the late Ordovician, the focus of major orogenic activity in South America was located along the present western and southern margins of the craton, and tended to migrate westwards during the Palaeozoic.  相似文献   

Pyroxene geothermometry of some granulite facies rocks     

Roger H. Hewins 《Contributions to Mineralogy and Petrology》1975,50(3):205-209

Wood-and-Banno temperatures for the coexisting pyroxenes of equilibrated metamorphic rocks in the hornblende granulite subfaoies fall in the range 780–860° C. Minimum temperature estimates for granulites include 760–790 °C, from the dehydration of hornblende to an orthopyroxene assemblage, and about 800 °C, from other evidence. The pyroxene temperatures are generally consistent with these temperature estimates, and are certainly not too low or more than 50 ° too high. Pyroxene temperatures for the three subzones of Broken Hill granulites increase away from the orthopyroxene isograd and are sufficiently precise that the difference between the lowest and intermediate gubzones is statistically significant. Temperatures for pyroxenes in pyroxene-granulite subfacies rocks are greater than 860 °C. The internal consistency, precision and apparent accuracy of the Wood-and-Banno pyroxene geothermometer in the metamorphic temperature range make it an important tool.  相似文献   

Rare earth element geochemistry of the Fen alkaline complex,Norway     

Roger H. Mitchell  Arild O. Brunfelt 《Contributions to Mineralogy and Petrology》1975,52(4):247-259

Determination of rare earth element (REE) abundances in rocks of the Fen complex has shown that within rocks of the first magmatic series REE abundances increase in the order urtiteFen magmas are discussed and it is considered that parental magmas had relatively high La/Yb ratios (40–60). Utilizing petrological evidence from other alkaline complexes coupled with experimental studies it is considered that the parental magma was a carbonated nephelinite produced by limited (<10%) partial melting of the mantle. All the Fen rocks are placed in a petrogentic scheme in which a carbonated nephelinite magma undergoes liquid immiscibility, differentiation and volatile transport.  相似文献   

Eutrophication of a partially enclosed estuarine mudflat     

Edward Fahy  Roger Goodwillie  John Rochford  David Kelly 《Marine pollution bulletin》1975,6(2):29-31

Some 130 years ago, a small estuary to the north of Dublin was partly cut off from the sea by a railway causeway. The mudflats that formed became an important feeding ground for wildfowl. In recent years the estuary has become subject to increasing organic pollution. Algal growth has increased and while the situation is not yet damaging to wildfowl, there is evidence that further increase in nutrients would cause undesirable extension of algal mats in the estuary.  相似文献   

Reviews     

Roger L. Kaesler  D. F. Merriam 《Mathematical Geosciences》1975,7(3):279-284

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Mössbauer spectroscopy: An introduction for inorganic chemists and geochemists: G.M. Bancroft. Mc-Graw-Hill Book Co. (United Kingdom) Ltd., 1973, 252 pp., US $ 21.50     

Roger G. Burns 《Chemical Geology》1975,16(1):65-67

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