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Evidence for the applicability of GEK (Geomagnetic Electrokinetography) measurements to shallow water regions is provided
from observations in the shelf region of the East China Sea. The reason for the effectiveness of GEK measurements in this
case is investigated theoretically, and it is shown to be attributable to the existence of a thick conductive sedimentary
layer. In addition, it is shown that low conductive basement rock can be regarded as a good conductor for GEK measurements
if the current width is broad enough and if the ratio of current width to water depth is larger than the resistivity ratio
of basement rock to sea water. This implies that barotropic tidal currents can be measured with GEK in any ocean on the earth
if they have significant magnitudes. 相似文献
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To systematically explain relations between light hydrocarbons, CO, and CO2 concentrations/emissions of biomassburning, we measured concentrations/emissions of carbon gases – CO,CO2, light hydrocarbons (CH4, C2H6,C2H4, C2H2, C3H8, C3H6,n-C4H10, i-C4H10, n-C5H12,i-C5H12), and THC (total hydrocarbon) – in the burning of dead plant material, mainly Imperata grass, byclosed-chamber experiments and by time-series analyses of gas concentrations in combustion plumes in relatively efficient and inefficient combustion situations. Concentrations of hydrocarbons measured were well correlated to [CO] although [C2H2] was exceptionally well correlated to[CO2]. The phase diagrams (relation between [CO]/ [CO2] and [hydrocarbon]/ [CO2]) obtained by the time-seriesexperiments well illustrated the variation in the overall emission rates of the closed-chamber experiments. The higher rates of decrease in hydrocarbon concentration with increasing carbon number in the efficient case compared with the inefficient case probably reflected the rate of oxidation and the amount of radicals. The overall concentrations (or emissions) of C2H4 and C3H6 were higher thanthose of C2H6 and C3H8, suggesting a linkage to mechanisms in whichthe predominant path of hydrocarbon oxidation is through the degradation of alkyl radicals, which can be immediately converted into or formed from alkenes. For C3 and C4 species, normal-chain species hadhigher emissions than iso-chain species under lower combustion efficiency. This may be attributable to the presence of tertiary C–H bonds in iso-species,which show more reactivity in the abstraction of H than secondary C–H bonds unless the carbon number is large. 相似文献
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Toshiyuki Ohtsuka Mitsuru Hirota Xianzhou Zhang Ayako Shimono Yukiko Senga Minguan Du Seiichiro Yonemura Shigeto Kawashima Yanhong Tang 《Polar Science》2008,2(4):277-285
To accurately estimate soil organic carbon (SOC) storage in upper alpine to nival zones on the Tibetan Plateau, we inventoried SOC pools in 0–0.3 m profiles along an altitudinal gradient (4400–5300 m asl). We also studied vegetation properties and decomposition activity along the gradient to provide insight into the mechanisms of SOC storage. The vegetation cover and belowground root biomass showed a gradual increased with altitude, reaching a peak in the upper alpine zone at 4800–4950 m before decreasing in the nival zone at 5200–5300 m.Decomposition activity was invariant along the altitudinal gradient except in the nival zone. SOC pools at lower sites were relatively small (2.6 kg C m−2 at 4400 m), but increased sharply with altitude, reaching a peak in the upper alpine zone (4950 m; 13.7 kg C m−2) before decreasing (1.0 kg C m−2 at 5300 m) with altitude in the nival zone. SOC pool varied greatly within individual alpine meadows by a factor of five or more, as did bulk density, partly due to the effect of grazing. Inventory data for both carbon density and bulk density along altitudinal gradients in alpine ecosystems are of crucial importance in estimating global tundra SOC storage. 相似文献
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S. Yonemura S. Kawashima H. Matsueda Y. Sawa S. Inoue H. Tanimoto 《Theoretical and Applied Climatology》2008,92(1-2):47-58
Summary The application of principal components and cluster analysis to vertical ozone concentration profiles in Tsukuba, Japan, has
been explored. Average monthly profiles and profiles of the ratio between standard deviation and the absolute ozone concentration
(SDPR) of 1 km data were calculated from the original ozone concentration data. Mean (first) and gradient (second) components
explained more than 80% of the variation in both the 0–6 km tropospheric and 11–20 km troposphere–stratosphere (interspheric)
layers. The principal components analysis not only reproduced the expected inverse relationship between mean ozone concentration
and tropopause height (r
2 = 0.41) and that in the tropospheric layer this is larger in spring and summer, but also yielded new information as follows.
The larger gradient component score in summer for the interspheric layer points to the seasonal variation of the troposphere–stratosphere
exchange. The minimum SDPR was at about 3 km in the tropospheric layer and the maximum was at about 17 km in the interspheric
layer. The tropospheric SDPR mean component score was larger in summer, possibly reflecting the mixing of Pacific maritime
air masses with urban air masses. The cluster analysis of the monthly ozone profiles for the 1970s and 2000s revealed different
patterns for winter and summer. The month of May was part of the winter pattern in the 1970s but part of the summer pattern
during the 2000s. This statistically detected change likely reflects the influence of global warming. Thus, these two statistical
analysis techniques can be powerful tools for identifying features of ozone concentration profiles.
Authors’ addresses: S. Yonemura, S. Kawashima, S. Inoue, National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai,
Tsukuba, Ibaraki 305-0031, Japan; H. Matsueda, Y. Sawa, Meteorological Research Institute, 1-1 Nagamine, Tsukuba, Ibaraki
305-0052, Japan; H. Tanimoto, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan. 相似文献
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Volume Contents
Contents to Volume 43 相似文献
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