Revisiting forest impact on atmospheric water vapor transport and precipitation   总被引：1，自引：0，他引：1  

Anastassia M. Makarieva  Victor G. Gorshkov  Bai-Lian Li 《Theoretical and Applied Climatology》2013,111(1-2):79-96

Using a robust global precipitation database, we analyze coast-to-interior seasonal precipitation distributions over the world’s major forest regions. We find that the active functioning of boreal forests in summer is associated with an intense ocean-to-land moisture transport, which declines in winter when forest functioning is minimal. This seasonal switch manifests itself as a change in the exponential scale length of precipitation distribution, which exceeds 15?×?10³ km in summer but decreases to (3–4)?×?10³ km in winter. In equatorial rainforests, which are photosynthetically active throughout the year, annual precipitation remains approximately constant, while the coefficient of variation of monthly precipitation significantly declines toward the continent interior. Precipitation over forest during the periods of active forest functioning is always higher than over the adjacent ocean. Such precipitation patterns support the biotic pump concept according to which forest cover drives the ocean-to-land atmospheric moisture transport on a continental scale.  相似文献   

Morphological evolution of discs in clusters     

Chiara Mastropietro  Ben Moore  Lucio Mayer  Victor P. Debattista  Rocco Piffaretti  Joachim Stadel 《Monthly notices of the Royal Astronomical Society》2005,364(2):607-619

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The development of the Poincaré-similar elements with eccentric anomaly as the independent variable     

Victor R. Bond 《Celestial Mechanics and Dynamical Astronomy》1976,14(3):333-311

A new set of element differential equations for the perturbed two-body motion is derived. The elements are canonical and are similar to the classical canonical Poincaré elements, which have time as the independent variable. The phase space is extended by introducing the total energy and time as canonically conjugated variables. The new independent variable is, to within an additive constant, the eccentric anomaly. These elements are compared to the Kustaanheimo-Stiefel (KS) element differential equations, which also have the eccentric anomaly as the independent variable. For several numerical examples, the accuracy and stability of the new set are equal to those of the KS solution. This comparable accuracy result can probably be attributed to the fact that both sets have the same time element and very similar energy elements. The new set has only 8 elements, compared to 10 elements for the KS set. Both sets are free from singularities due to vanishing eccentricity and inclination.  相似文献   

The peaks and gaps in the redshift distributions of active galactic nuclei and quasars     

Andrei A. Kruogovenko  Victor V. Orlov 《Astrophysics and Space Science》1992,193(2):303-307

The distributionsf(z) of the redshifts for active galaxies (Seyfert galaxies, radio galaxies, and quasars) have been studied. Some statistically-significant maxima and minima are observed in the distributionsf(z) for these objects. The significance of peaks and gaps increases for the brighter objects, for which the samples are more complete. The clustering of the Seyfert galaxies is significantly different from that of the nearby normal galaxies. The distributionf(z) for the radio galaxies is similar to the analogous distribution for the galaxy clusters. Three of the five peaks in the distributionf(z) for the radio quasars may be caused by the selection effects. Two peaks within the intervalsz (0.5, 0.7) and (1.0, 1.1) are probably real. The corresponding scales of the QSO clustering along the line-of-sight are about 100h ^–1 Mpc (h is the Hubble constant in the units of 75 km s^–1 Mpc^–1). The possibility of some global quasi-periodical cycles for the processes of activity is discussed. The period of a cycle for the Seyfert and radio galaxies is about 1×10⁸ years that corresponds to the distances of about 30h ^–1 Mpc between the shells.  相似文献   

Liability for North Sea oil pollution     

Victor E. Fitzmaurice 《Marine Policy》1978,2(2):105-111

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The binaries and triple systems in an irregular field     

Joanna P. Anosova  Victor V. Orlov 《Astrophysics and Space Science》1989,161(2):209-220

The dynamical evolution of theN-body systems (N=6) has been studied by numerical simulations. The double and triple subsystems isolated from other bodies have been revealed. The processes of their formation, evolution, and disruption have been followed. At the initial stage of evolution, a common collapse of the system takes place. After that some fast triple approaches of single bodies are possible. At further stages, some physically connected triple subsystems are formed which are disrupted by the intruders or due to their own dynamical unstability. The dissipation mechanisms formulated by van Albada (1968) and Aarseth (1973) have been confirmed. At the final stage, double or hierarchical triple systems are formed.  相似文献   

On the information content of natural frequency spectra associated with different angular numbers     

Victor Barcilon 《Geophysical Journal International》1978,53(3):623-641

summary . The problem of inferring the speed of sound in a contained spherically symmetric fluid solely from its natural frequencies of vibration is considered. An investigation of the case in which the data consist of the two spectra associated with the angular numbers 0 and 1, suggests the possibility that a one-parameter family of slowness profiles can be constructed. These profiles are compatible with the data, up to first order in the non-uniformity of the fluid. It is conjectured that for other angular numbers, the loss of information increases as the difference between them increases.  相似文献   

The greening of the McGill Paleoclimate Model. Part I: Improved land surface scheme with vegetation dynamics   总被引：1，自引：1，他引：0  

Yi Wang  Lawrence A. Mysak  Zhaomin Wang  Victor Brovkin 《Climate Dynamics》2005,24(5):469-480

The formulation of a new land surface scheme (LSS) with vegetation dynamics for coupling to the McGill Paleoclimate Model (MPM) is presented. This LSS has the following notable improvements over the old version: (1) parameterization of deciduous and evergreen trees by using the models climatology and the output of the dynamic global vegetation model, VECODE (Brovkin et al. in Ecological Modelling 101:251–261 (1997), Global Biogeochemical Cycles 16(4):1139, (2002)); (2) parameterization of tree leaf budburst and leaf drop by using the models climatology; (3) parameterization of the seasonal cycle of the grass leaf area index; (4) parameterization of the seasonal cycle of tree leaf area index by using the time-dependent growth of the leaves; (5) calculation of land surface albedo by using vegetation-related parameters, snow depth and the models climatology. The results show considerable improvement of the models simulation of the present-day climate as compared with that simulated in the original physically-based MPM. In particular, the strong seasonality of terrestrial vegetation and the associated land surface albedo variations are in good agreement with several satellite observations of these quantities. The application of this new version of the MPM (the green MPM) to Holocene millennial-scale climate changes is described in a companion paper, Part II.

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Yi WangEmail: Phone: +1-514-3987448Fax: +1-514-3986115

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Palaeoproterozoic evaporites in Fennoscandia: implications for seawater sulphate, the rise of atmospheric oxygen and local amplification of the δ¹³C excursion     

Victor A. Melezhik  Anthony E. Fallick  Dmitry V. Rychanchik  Anton B. Kuznetsov 《地学学报》2005,17(2):141-148

This paper addresses global oxygenation and establishment of a marine sulphate reservoir in the Palaeoproterozoic. We report syn-depositional, marine, anhydrite-containing pseudomorphs after Ca-sulphates as widespread throughout the Tulomozero Formation in the SE Fennoscandian Shield, implying that surface waters were oxidized and a large SO marine reservoir was developed as early as 2100 Ma. The Ca-sulphates and associated magnesite and halite precipitated syn-depositionally from oxidized, evolved and modified seawater in coastal playa, sabkha and intertidal flat settings. ⁸⁷Sr/⁸⁶Sr and δ¹³C of associated ¹³C-rich stromatolitic dolostones were environmentally controlled with the highest ratios occurring in playa and sabkha carbonates. The results imply that the Palaeoproterozoic δ¹³C_carb excursion was amplified by 8‰ by local environmental factors and calls into question many observations of putative δ¹³C global signals reported previously from similar Palaeoproterozoic, evaporitic, dolostones. The local environmental amplification can explain a large regional and intercontinental δ¹³C discrepancy observed in synchronous carbonates.  相似文献   

Continental drift and the rotation of the earth-a new and critical evaluation     

Victor J. Slabinski 《Celestial Mechanics and Dynamical Astronomy》1981,25(1):89-91

Sconzo has proposed that the continental drift of a land mass like Greenland can make a detect-able change in the Earth's rotation rate through a change in the Earth's moment of inertia. The correction of theoretical and numerical errors in his paper results in a change in the length of the day of only 3.5×10^–8 s cy^–1, a rate which is 6 orders of magnitude less than the value he gives. Continental drift does not appear to cause an important change in the length of the day.  相似文献