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1.
Tomoki Oda Tomohiro Egusa Nobuhito Ohte Norifumi Hotta Nobuaki Tanaka Mark B. Green Masakazu Suzuki 《水文研究》2021,35(5):e14177
Understanding changes in evapotranspiration during forest regrowth is essential to predict changes of stream runoff and recovery after forest cutting. Canopy interception (Ic) is an important component of evapotranspiration, however Ic changes and the impact on stream runoff during regrowth after cutting remains unclear due to limited observations. The objective of this study was to examine the effects of Ic changes on long-term stream runoff in a regrowth Japanese cedar and Japanese cypress forest following clear-cutting. This study was conducted in two 1-ha paired headwater catchments at Fukuroyamasawa Experimental Watershed in Japan. The catchments were 100% covered by Japanese coniferous plantation forest, one of which was 100% clear-cut in 1999 when the forest was 70 years old. In the treated catchment, annual runoff increased by 301 mm/year (14% of precipitation) the year following clear-cutting, and remained 185 mm/year (7.9% of precipitation) higher in the young regrowth forest for 12–14 years compared to the estimated runoff assuming no clear-cutting. The Ic change was −358 mm/year (17% of precipitation) after cutting and was −168 mm/year (6.7% of precipitation) in the 12–14 years old regrowth forest compared to the observed Ic during the pre-cutting period. Stream runoff increased in all seasons, and the Ic change was the main fraction of evapotranspiration change in all seasons throughout the observation period. These results suggest that the change in Ic accounted for most of the runoff response following forest cutting and the subsequent runoff recovery in this coniferous forest. 相似文献
2.
C.A. Mendoza-Briceño 《Astrophysics and Space Science》1997,256(1-2):387-392
The thermal evolution of structures is investigated for different values of the size of structure. A simplified cooling function and a constant heating mechanism are assumed. Analytical criteria for thermal instability are obtained. It is found that the response of the thermal structure not only depends on the amplitude of the disturbances, but also on whether the disturbance increases or decreases the initial steady temperature. Additionally, the evolution of the structure is examined numerically by using a time-dependent code under the assumption that the inertia terms are small. In particular, the analytical criteria obtained for thermal instability are verified. 相似文献
3.
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Ezio Caroli Natalia Auricchio Lorenzo Amati Yuriy Bezsmolnyy Carl Budtz-JøRgensen Rui M. Curado da Silva Filippo Frontera Alessandro Pisa Stefano Del Sordo John B. Stephen Giulio Ventura 《Experimental Astronomy》2005,20(1-3):341-351
The energy range above 60 keV is important for the study of many open problems in high energy astrophysics such as the role of Inverse Compton with respect to synchrotron or thermal processes in GRBs, non thermal mechanisms in SNR, the study of the high energy cut-offs in AGN spectra, and the detection of nuclear and annihilation lines. Recently the development of high energy Laue lenses with broad energy bandpasses from 60 to 600keV have been proposed for a Hard X ray focusing Telescope (HAXTEL) in order to study the X-ray continuum of celestial sources. The required focal plane detector should have high detection efficiency over the entire operative range, a spatial resolution of about 1mm, an energy resolution of a few keV at 500keV and a sensitivity to linear polarization. We describe a possible configuration of the focal plane detector based on several CdTe/CZT pixelated layers stacked together to achieve the required detection efficiency at high energy.
Each layer can operate both as a separate position sensitive detector and polarimeter or work with other layers to increase the overall photopeak efficiency. Each layer has a hexagonal shape in order to minimize the detector surface required to cover the lens field of view. The pixels would have the same geometry so as to provide the best coupling with the lens point spread function and to increase the symmetry for polarimetric studies. 相似文献
5.
6.
Miguel Cerviño 《Astrophysics and Space Science》2003,284(2):897-900
Evolutionary synthesis models have been used to study the physical properties of unresolved populations in a wide range of
scenarios. Unfortunately, their self-consistency is difficult to test and there are some theoretical open questions without
an answer: (1) The change of the homology relations assumed in the computation of isochrones due to the effect of stellar
winds (or rotation) and the discontinuities in the stellar evolution are not considered. (2) There is no consensus about how
the isochrones must be integrated. (3) The discreteness of the stellar populations (that produce an intrinsic statistical
dispersion) usually are not taken into account, and model results are interpreted in a deterministic way instead of a statistical
one. The objective of this contribution is to present some inconsistencies in the computation and some cautions in the application
of the results of such codes.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
7.
Flare activity was observed near the limb with two coronagraphs at the Norikura Solar Observatory and the Soft X-ray Crystal Spectrometer (SOX) aboard HINOTORI. A prominence activation occurred and then Hα brightenings were seen on the disk near the prominence. The prominence became very bright and its electron density increased to 1012.8 cm?3 in 1/2 hour. Loop prominence systems appeared above the Hα brightenings about half an hour after the onset of the flare, and were observed in the coronal lines CaXV 5694Å, FeXIV 5303Å, and FeX 6374Å. Shifted and asymmetric profiles of the emission line of 5303Å were sometimes observed, and turbulent phenomena occurred even in the thermal phase. The energy release site of the flare at the onset would be lower than 20 000 km above the solar limb. 相似文献
8.
Kyu Han Kim Keisuke Nagao Hirochika Sumino Tsuyoshi Tanaka Takamasa Hayashi Toshio Nakamura Jong Ik Lee 《Chemical Geology》2008,253(3-4):180-195
We report analyses of noble gases and Nd–Sr isotopes in mineral separates and whole rocks of late Pleistocene (< 0.2 Ma) monzonites from Ulleungdo, South Korea, a volcanic island within the back arc basin of the Japan island arc. A Rb–Sr mineral isochron age for the monzonites is 0.12 ± 0.01 Ma. K–Ar biotite ages from the same samples gave relatively concordant ages of 0.19 ± 0.01and 0.22 ± 0.01 Ma. 40Ar/39Ar yields a similar age of 0.29 ± 0.09 Ma. Geochemical characteristics of the felsic plutonic rocks, which are silica oversaturated alkali felsic rocks (av., 12.5 wt% in K2O + Na2O), are similar to those of 30 alkali volcanics from Ulleungdo in terms of concentrations of major, trace and REE elements. The initial Nd–Sr isotopic ratios of the monzonites (87Sr/86Sr = 0.70454–0.71264, 143Nd/144Nd = 0.512528–0.512577) are comparable with those of the alkali volcanics (87Sr/86Sr = 0.70466–0.70892, 143Nd/144Nd = 0.512521–0.512615) erupted in Stage 3 of Ulleungdo volcanism (0.24–0.47 Ma). The high initial 87Sr/86Sr values of the monzonites imply that seawater and crustally contaminated pre-existing trachytes may have been melted or assimilated during differentiation of the alkali basaltic magma.A mantle helium component (3He/4He ratio of up to 6.5 RA) associated with excess argon was found in the monzonites. Feldspar and biotite have preferentially lost helium during slow cooling at depth and/or during their transportation to the surface in a hot host magma. The source magma noble gas isotopic features are well preserved in fluid inclusions in hornblende, and indicate that the magma may be directly derived from subcontinental lithospheric mantle metasomatized by an ancient subduction process, or may have formed as a mixture of MORB-like mantle and crustal components. The radiometric ages, geochemical and Nd–Sr isotopic signatures of the Ulleungdo monzonites as well as the presence of mantle-derived helium and argon, suggests that these felsic plutonic rocks evolved from alkali basaltic magma that formed by partial melting of subcontinental lithospheric mantle beneath the back arc basin located along the active continental margin of the southeastern part of the Eurasian plate. 相似文献
9.
10.
Reactive dissolved Hg (HgR), non-reactive dissolved Hg (HgNR), particulate Hg (HgP), dissolved organic C (DOC), particulate organic C (POC), salinity and other interpretative parameters were determined in water samples collected in the North Channel and in adjacent areas of the Tagus estuary (Portugal). Higher concentrations of both dissolved and particulate Hg in the North Channel indicate a pollution source and raise the possibility of Hg escaping to adjacent areas by tidal action. This transport was confirmed by the increase of HgR with salinity and HgNR with DOC, along a longitudinal axis paralleling the North Channel. Apparently, Hg leaving this channel is progressively complexed by inorganic and organic ligands. Near the mouth of the estuary, values decreased reflecting dilution with seawater. Moreover the HgP:POC ratio also increased seaward, suggesting mixing with Hg enriched particles that escaped the North Channel, or incorporation of dissolved Hg species in river-derived particles. These results suggest that the pathway of anthropogenic Hg in contaminated waters may be identified by their enrichment in organic matter, both in the dissolved and particulate fraction. 相似文献