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21.
The carbon cycle module of the global climate model developed at the Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (IAP RAS CM) has been extended by implementing the subgrid-scale heterogeneity (SH) of plant functional types (PFTs). It is found that subgrid-scale PFT heterogeneity enhances the photosynthesis intensity and increases vegetation and soil carbon stocks in grass-dominated regions. In forest-dominated regions, photosynthesis is suppressed and vegetation and soil carbon stocks are diminished. Regionally, accounting for subgrid-scale vegetation heterogeneity may lead to twofold changes in these variables. On the whole, accounting for subgrid-scale PFT heterogeneity enhances (suppresses) the carbon flux in regions where it is directed from terrestrial ecosystems to the atmosphere (from the atmosphere to terrestrial ecosystems). 相似文献
22.
M.?Yu.?KoreshkovaEmail author H.?Downes V.?A.?Glebovitsky N.?V.?Rodionov A.?V.?Antonov S.?A.?Sergeev 《Contributions to Mineralogy and Petrology》2014,167(2):973
Garnet granulite and pyroxenite xenoliths from the Grib kimberlite pipe (Arkhangelsk, NW Russia) represent the lower crust beneath Russian platform in close vicinity to the cratonic region of the north-eastern Baltic (Fennoscandian) Shield. Many of the xenoliths have experienced strong interaction with the kimberlite host, but in others some primary granulite-facies minerals are preserved. Calculated bulk compositions for the granulites suggest that their protoliths were basic to intermediate igneous rocks; pyroxenites were ultrabasic to basic cumulates. A few samples are probably metasedimentary in origin. Zircons are abundant in the xenoliths; they exhibit complex zoning in cathodoluminescence with relic cores and various metamorphic rims. Cores include oscillatory zircon crystallized in magmatic protoliths, and metamorphic and magmatic sector-zoned zircons. Recrystallization of older zircons led to the formation of bright homogeneous rims. In some samples, homogeneous shells are surrounded by darker convoluted overgrowths that were formed by subsolidus growth when a change in mineral association occurred. The source of Zr was a phase consumed during a reaction, which produced garnet. Late-generation zircons in all xenoliths show concordant U–Pb ages of 1.81–1.84 Ga (1,826 ± 11 Ma), interpreted as the age of last granulite-facies metamorphism. This event completely resets most zircon cores. An earlier metamorphic event at 1.96–1.94 Ga is recorded by some rare cores, and a few magmatic oscillatory zircons have retained a Neoarchaean age of 2,719 ± 14 Ma. The assemblage of metaigneous and metasedimentary rocks was probably formed before the event at 1.96 Ga. Inherited magmatic zircons indicate the existence of continental crust by the time of intrusion of magmatic protoliths in the Late Archaean. The U–Pb zircon ages correspond to major events recorded in upper crustal rocks of the region: collisional metamorphism and magmatism 2.7 Ga ago and reworking of Archaean rocks at around 1.95–1.75 Ga. However, formation of the granulitic paragenesis in lower crustal rocks occurred significantly later than the last granulite-facies event seen in the upper crust and correlates instead with retrograde metamorphism and small-volume magmatism in the upper crust. 相似文献
23.
We present results of photometric observations of the young eclipsing system KH 15D made during two observational seasons, 2002–2004. A comparison of our data with the earlier results of Hamilton et al. and Herbst et al. reveals the existence of a multiyear photometric trend in the brightness: over a period of 5 years the brightness of the system in the Ic band decreased by almost 1 stellar magnitude. It is also shown that the systematic variations in the eclipse parameters reported by Herbst et al. continue to the present. The shape of the light curve has not changed significantly and, as before, it is characterized by a slight brightening in the central portion of the eclipses. These results are discussed in the context of current models for KH 15D.Translated from Astrofizika, Vol. 48, No. 1, pp. 5–14 (February 2005). 相似文献
24.
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26.
CCD photometry data of the T Tauri star H 187 are presented. They show that a new eclipse of this star began at the end of
2004. Since only one eclipse of this star has been observed previously with a duration of 3.5 years, our data indicate that
the eclipses of this object are periodic with a period P=4.9 years between eclipses. Thus, in terms of the absolute duration
of the eclipses and in terms of their relative length as a fraction of the period, H 187 is one of the most exotic objects
in the sky.
__________
Translated from Astrofizika, Vol. 48, No. 4, pp. 529–534 (November 2005). 相似文献
27.
28.
Ten years data set is used to separate the influence of IMF Bz-component and solar wind speed on the dawn-dusk component of magnetic variations in the summer polar cap. The reference level was chosen from most quiet periods of winter solstices (small polar cap and auroral zone conductivity) to exclude the inner source component. The linear regression analysis was then used to calculate the PC variation response to Bz under different ranges of solar wind speed. As a result, taking into account the value of polar cap conductivity and effects of induced currents, the response of dawn-dusk electric field component to Bz and V was obtained and the potential difference across the polar cap was estimated to be for Bz ? + 1γ. The results give a proof for simultaneous operation in the magnetosphere of two electric field generation mechanisms, related to the boundary layer processes and magnetic field reconnection. The above-mentioned functional form was shown to correlate effectively with AE index (R = 0.73). 相似文献
29.
Vera K. Rosenbush Vasilij G. Shevchenko Alexander V. Sergeev Feodor P. Velichko Nikolai V. Karpov 《Icarus》2009,201(2):655-665
We present new polarimetric and photometric observations of high-albedo E-type Asteroid 44 Nysa in the BVRI wavebands at phase angles ranging from 0.41° to 7.49° during the 2005 opposition. A bimodal phase-angle dependence of polarization was found for Nysa in the V band. The polarization opposition effect was revealed in the form of a secondary minimum of negative polarization with amplitude ∼0.3% centered at a phase angle ∼0.8°. It is superimposed on the regular negative polarization branch with minimal polarization −0.30% at a phase angle 5.8°. We analyzed all available polarimetric data for E-type Asteroids 44 Nysa, 64 Angelina, and 214 Ashera and confirmed the presence of the polarization opposition effect for high-albedo asteroids at phase angle ∼1° with an amplitude ∼0.35%. The magnitude-phase curves reveal the presence of spike-like opposition effect of brightness for 44 Nysa in the BVRI spectral bands. 44 Nysa is the second high-albedo asteroid after 64 Angelina for which both the polarization opposition effect and the brightness opposition effect are detected. The differences between the parameters of the opposition effects for silicate surfaces (44 Nysa, 64 Angelina, Io) and icy surfaces (Europa, Ganymede, Iapetus, Saturn's rings) are discussed. The specific morphological parameters of opposition effects, in particular the angular width of the polarization opposition effect is comparable to that of the brightness opposition effect, provide almost unequivocal evidence that they are caused by coherent backscattering. One of unexpected results of our investigation is that 44 Nysa becomes bluer with increasing phase angle, while 64 Angelina shows phase reddening. 相似文献
30.
Chesnokova I. V. Bezdelova A. P. Sergeev D. O. Tananaev N. I. Grishakina E. A. 《Water Resources》2021,48(5):804-812
Water Resources - The subsurface runoff in the permafrost zone shows considerable structural and seasonal specifics. The structural features are due, on the one hand, to the lithologically... 相似文献